A slow-wave circuit, electromagnetic wave processing method, and related device

Abstract

The application relates to the field of microwave vacuum electron technology, in particular to a slow wave circuit, an electromagnetic wave processing method and related equipment. The slow wave circuit comprises a first cavity and N1 first photonic crystal columns arranged in a first preset direction on a first inner plane of the first cavity and N2 second photonic crystal columns arranged on both sides of the N1 first photonic crystal columns. Here, the height of the first photonic crystal column is less than the height of the second photonic crystal column. The first preset direction is the direction of travel of an electromagnetic wave and an electron beam in the first cavity. The slow wave circuit can amplify the power of a first electromagnetic wave transmitted in the first cavity based on a first electron beam transmitted in the first cavity, and output a power-amplified second electromagnetic wave and a power-attenuated second electron beam. The slow wave circuit provided by the application can improve the working bandwidth of a traveling wave tube and reduce the working voltage of the traveling wave tube.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microwave vacuum electron technology, and in particular, to a slow wave circuit, an electromagnetic wave processing method, and related equipment. BACKGROUND

[0002] Compared with solid-state electronic devices, a traveling wave tube (TWT) has outstanding advantages such as a wide frequency band, high gain, and long service life. Therefore, the use frequency and range of the TWT in wireless communication systems such as satellite communication or radar are increasingly increasing. The so-called traveling wave tube refers to a vacuum electron device that can realize an amplification function by continuously modulating the speed of an electron beam. In the traveling wave tube, the electron beam interacts with an electromagnetic wave traveling in a slow wave structure (SWS) (which can also be referred to as a slow wave circuit, and hereinafter will be uniformly described as a slow wave circuit), and the electron beam can convert its kinetic energy to the electromagnetic wave, thereby completing power amplification of the electromagnetic wave. As a core component of the traveling wave tube, the characteristics of the slow wave circuit can directly determine the performance of the traveling wave tube. For example, different structures of the slow wave circuit can make the operating voltage and operating bandwidth of the traveling wave tube different. With the development of the traveling wave tube to the terahertz (THz) band, the size of the slow wave circuit is required to be smaller and smaller, and the reduction of the size reduces the performance of the slow wave circuit, thereby limiting the application of the traveling wave tube in the terahertz band. Therefore, how to design a small-size and high-performance slow wave circuit has become a current research hotspot.

[0003] In the prior art, the slow wave circuit based on the staggered double-gate structure loaded by a photonic crystal or the folded waveguide structure loaded by a photonic crystal is usually applied to the traveling wave tube in the terahertz band. However, these structures of the slow wave circuit all have problems such as a narrow operating bandwidth, a high operating voltage, and a high assembly precision requirement, which greatly affect the performance of the traveling wave tube. Therefore, a high-performance slow wave circuit is urgently needed. SUMMARY

[0004] To solve the above problems, the present application provides a slow wave circuit, an electromagnetic wave processing method, and related equipment. The slow wave circuit provided by the present application can improve the operating bandwidth of the traveling wave tube and reduce the operating voltage of the traveling wave tube, and can improve the applicability and practicality of the traveling wave tube in the terahertz band.

[0005] In a first aspect, the present application provides a slow wave circuit. The slow wave circuit comprises a first cavity and N1 first photonic crystal columns and N2 second photonic crystal columns arranged on a first inner plane of the first cavity. The N1 first photonic crystal columns are arranged in a first preset direction in sequence and the N2 second photonic crystal columns are arranged in sequence on both sides of the N1 first photonic crystal columns. The height of the first photonic crystal columns in a second preset direction is less than the height of the second photonic crystal columns in the second preset direction. The first preset direction is the direction of travel of an electromagnetic wave and an electron beam in the slow wave circuit, the second preset direction is perpendicular to the first inner plane, N1 is a positive integer greater than or equal to 1, and N2 is a positive integer greater than or equal to 2. In actual use, the first cavity is used to receive and transmit a first electromagnetic wave and a first electron beam. The N1 first photonic crystal columns and the N2 second photonic crystal columns are used to amplify the power of the first electromagnetic wave based on the first electron beam while reducing the phase velocity of the first electromagnetic wave, so that the first cavity outputs a second electromagnetic wave and a second electron beam, wherein the phase velocity of the second electromagnetic wave is lower than that of the first electromagnetic wave, the power of the second electromagnetic wave is greater than that of the first electromagnetic wave, and the power of the second electron beam is less than that of the first electron beam.

[0006] In the above implementation, the first inner plane of the first cavity of the slow wave circuit regularly arranges N1 first photonic crystal columns and N2 second photonic crystal columns with different heights, and the N1 first photonic crystal columns and the N2 second photonic crystal columns form a special defect structure due to the difference in height. On the one hand, the defect structure composed of a plurality of regularly arranged photonic crystal columns can significantly reduce the phase velocity of the first electromagnetic wave transmitted in the first cavity, so that the first electromagnetic wave can be transmitted at a lower phase velocity in the first cavity, which can reduce the operating voltage requirement of the slow wave circuit on the first electron beam. On the other hand, since the transmission mode supported by the first cavity is a new transmission mode generated by the N1 first photonic crystal columns in the photonic crystal band gap, the mode will not be affected by the photonic crystal band gap, so that the slow wave circuit can have a wider operating bandwidth. Since the slow wave circuit with the above structure has a wider operating bandwidth and can interact with a lower voltage electron beam, the slow wave circuit has a wide operating bandwidth and a low operating voltage. Therefore, by using such a slow wave circuit, the operating bandwidth of the traveling wave tube can be improved and the operating voltage of the traveling wave tube can be reduced, and the applicability and practicality of the traveling wave tube in the terahertz wave band can be improved.

[0007] In some possible implementation manners of the first aspect, each of the N1 first photonic crystal columns is not blocked by the N2 second photonic crystal columns in the first preset direction, each of the N1 first photonic crystal columns has the same size, and each of the N2 second photonic crystal columns has the same size.

[0008] In some possible implementation manners of the first aspect, the N1 first photonic crystal columns and the N2 second photonic crystal columns form N3 photonic crystal arrays on the first inner plane. The N3 photonic crystal arrays are arranged in sequence in the first preset direction, one photonic crystal array includes one first photonic crystal and at least two second photonic crystals, and the at least two second photonic crystals are arranged in sequence on two sides of the one first photonic crystal. N3 is a positive integer greater than or equal to 1.

[0009] In the implementation manner, arranging the N1 first photonic crystal columns and the N2 second photonic crystal columns in the form of N3 photonic crystal arrays with the same structure on the first inner plane can make the structure of the slow wave circuit more regular, which can facilitate the design and production of the slow wave circuit, and can also flexibly adjust the performance of the slow wave circuit by the number of photonic crystal arrays, thereby improving the functional flexibility of the slow wave circuit.

[0010] In some possible implementation manners of the first aspect, the photonic crystal array is an arc-shaped array in a third preset direction, and the opening direction of the arc-shaped array is the first preset direction, or the photonic crystal array is a linear array in the third preset direction. The third preset direction is perpendicular to the first preset direction and parallel to the first inner plane.

[0011] In some possible implementation manners of the first aspect, the first photonic crystal column and the second photonic crystal column are rectangular columns, the height of the first photonic crystal column in the second preset direction is equal to half of the height of the second photonic crystal column in the second preset direction, the length of the first photonic crystal column in the first preset direction is equal to two-thirds of the length of the second photonic crystal column in the first preset direction, and the width of the first photonic crystal column in the third preset direction is equal to the width of the second photonic crystal column in the third preset direction.

[0012] In some possible implementation manners of the first aspect, the first cavity further includes a second inner plane, the second inner plane is parallel to the first inner plane, and the distance between the second inner plane and the first inner plane in the second preset direction is equal to the height of the second photonic crystal column in the second preset direction.

[0013] With reference to the first aspect, in a possible implementation form of the first aspect, the slow-wave circuit comprises a slow-wave component and a first waveguide conversion component, the slow-wave component comprises the first cavity and N1 first photonic crystal columns and N2 second photonic crystal columns arranged on a first inner plane of the first cavity, and the first waveguide conversion component is connected to the slow-wave component. In actual use, when the transmission mode of the first electromagnetic wave is a first transmission mode, the first waveguide conversion component is configured to transmit the received first electron beam to the slow-wave component, convert the received source electromagnetic wave of a second transmission mode into the first electromagnetic wave of the first transmission mode, and transmit the first electromagnetic wave to the slow-wave component, wherein the first transmission mode is different from the second transmission mode. The slow-wave component is configured to convert the received first electromagnetic wave and first electron beam into the second electromagnetic wave and the second electron beam and output.

[0014] In the above implementation, the first waveguide conversion component converts the source electromagnetic wave of the second transmission mode received by the slow-wave circuit into the first electromagnetic wave of the first transmission mode supported by the slow-wave component composed of the first cavity, N1 first photonic crystal columns and N2 second photonic crystal columns arranged on the first inner plane of the first cavity, so that the slow-wave circuit can complete power amplification of electromagnetic waves of different transmission modes, and the functional flexibility and applicability of the slow-wave circuit can be improved.

[0015] With reference to the first aspect, in a possible implementation form of the first aspect, the first waveguide conversion component is provided with a second cavity, a third inner plane of the second cavity is parallel to the first preset direction, and N4 third photonic crystal columns and N5 second photonic crystal columns are arranged on the third inner plane. The N4 third photonic crystal columns are arranged in sequence along the first preset direction, and the N5 second photonic crystal columns are arranged in sequence on both sides of the N4 third photonic crystal columns. The height of each third photonic crystal column in the N4 third photonic crystal columns in the second preset direction increases in sequence in the first preset direction. The height of the third photonic crystal column with the largest height in the N4 third photonic crystal columns in the second preset direction is equal to the height of the first photonic crystal column in the second preset direction. The height of each second photonic crystal column in the N5 second photonic crystal columns in the second preset direction is the same. N4 and N5 are positive integers greater than or equal to 2.

[0016] With reference to the first aspect, in a possible implementation form of the first aspect, each third photonic crystal column in the N4 third photonic crystal columns is not blocked by the N5 second photonic crystal columns in the first preset direction.

[0017] In the above implementation, the first waveguide conversion component is realized by arranging N4 third photonic crystal pillars and N5 second photonic crystal pillars on the third inner plane of the second cavity. On the one hand, the first waveguide conversion component has a simple structure and good device stability. On the other hand, the first waveguide conversion component and the slow wave component are structurally similar and have good compatibility.

[0018] In conjunction with the first aspect, in one feasible implementation, the shape of the second cavity is jointly determined by the transmission mode of the electromagnetic wave entering the first waveguide conversion component and the transmission mode of the electromagnetic wave output by the first waveguide conversion component.

[0019] In conjunction with the first aspect, in one feasible implementation, the slow-wave circuit further includes a second waveguide conversion component connected to the slow-wave component. In practical use, the second waveguide conversion component is used to conduct and output the second electron beam, and also to convert the second electromagnetic wave into a third electromagnetic wave with a third transmission mode, and output the third electromagnetic wave. The third transmission mode is different from the first transmission mode.

[0020] In the above implementation, the second electromagnetic wave of the first transmission mode output by the slow wave component is converted into a third electromagnetic wave of a different third transmission mode by the second waveguide conversion component and then output. This enables the slow wave circuit to output electromagnetic waves of different transmission modes after power amplification, which can further improve the functional flexibility and applicability of the slow wave circuit.

[0021] In conjunction with the first aspect, in one feasible implementation, the second waveguide conversion component includes a third cavity. The fourth inner plane of the third cavity is parallel to the first preset direction. N6 fourth photonic crystal pillars and N7 second photonic crystal pillars are disposed on the fourth inner plane. The N6 fourth photonic crystal pillars are arranged sequentially along the first preset direction, and the N7 second photonic crystal pillars are arranged sequentially on both sides of the N6 fourth photonic crystal pillars. The height of each of the N6 fourth photonic crystal pillars in the second preset direction decreases sequentially in the first preset direction. The fourth photonic crystal pillar with the largest height among the N6 fourth photonic crystal pillars has a height in the second preset direction equal to the height of the first photonic crystal pillar in the second preset direction. Each of the N7 second photonic crystal pillars has the same height in the second preset direction. N6 and N7 are positive integers greater than or equal to 2.

[0022] In conjunction with the first aspect, in one feasible implementation, each of the N6 fourth photonic crystal pillars will not be blocked by the N7 second photonic crystal pillars in the first preset direction.

[0023] In the above implementation, the second waveguide conversion component is implemented by arranging N6 third photonic crystal columns and N7 second photonic crystal columns on the fourth inner plane of the third cavity. On the one hand, the second waveguide conversion component has a simple structure and good device stability. On the other hand, the second waveguide conversion component has a structure similar to the slow wave component, and has good compatibility.

[0024] In combination with the first aspect, in a feasible implementation, the shape of the third cavity is determined by the transmission mode of the electromagnetic wave entering the second waveguide conversion component and the transmission mode of the electromagnetic wave output by the second waveguide conversion component.

[0025] In combination with the first aspect, in a feasible implementation, the slow wave circuit further includes a first electromagnetic interface and a second electromagnetic interface. The first electromagnetic interface is connected with the first waveguide conversion component and a first waveguide externally connected with the slow wave circuit. The second electromagnetic interface is connected with the second waveguide conversion component and a second waveguide externally connected with the slow wave circuit. The first electromagnetic interface is internally provided with a first electron beam channel and a first electromagnetic wave channel. The second electromagnetic interface is internally provided with a second electron beam channel and a second electromagnetic wave channel. In actual use, the first electron beam channel is used to receive the first electron beam from outside the slow wave circuit and transmit the first electron beam to the first waveguide conversion component. The first electromagnetic wave channel is used to receive the source electromagnetic wave from the first waveguide and transmit the source electromagnetic wave to the first waveguide conversion component. The second electron beam channel is used to receive the second electron beam from the second waveguide conversion component and transmit the second electron beam to the outside of the slow wave circuit. The second electromagnetic wave channel is used to receive the third electromagnetic wave from the second waveguide conversion component and transmit the third electromagnetic wave to the second waveguide.

[0026] In combination with the first aspect, in a feasible implementation, the first waveguide and the second waveguide are standard rectangular waveguides. The second cavity of the first waveguide conversion component and the third cavity of the second waveguide conversion component have an isosceles trapezoidal cross section parallel to the first preset direction and the third preset direction. The length of the side of the cross section close to the slow wave component is smaller than the length of the side of the cross section close to the first electromagnetic interface and / or the second electromagnetic interface.

[0027] In combination with the first aspect, in a feasible implementation, the first cavity has a rectangular cross section parallel to the first preset direction and the third preset direction.

[0028] In a second aspect, the embodiments of the present application further provide an electromagnetic wave processing method, which is applicable to the slow wave circuit of the first aspect. The slow wave circuit comprises a first cavity and N1 first photonic crystal columns and N2 second photonic crystal columns arranged on a first inner plane of the first cavity. The N1 first photonic crystal columns are arranged in sequence along a first preset direction, the N2 second photonic crystal columns are arranged in sequence on both sides of the N1 first photonic crystal columns, the height of the first photonic crystal column in a second preset direction is less than the height of the second photonic crystal column in the second preset direction, the first preset direction is the direction of travel of the electromagnetic wave and the electron beam in the slow wave component, the second preset direction is perpendicular to the first inner plane, N1 is a positive integer greater than or equal to 1, and N2 is a positive integer greater than or equal to 2. The first electromagnetic wave and the first electron beam can be received through the first cavity. The N1 first photonic crystal columns and the N2 second photonic crystal columns reduce the phase velocity of the first electromagnetic wave while amplifying the power of the first electromagnetic wave based on the first electron beam, so that the first cavity outputs a second electromagnetic wave and a second electron beam, wherein the phase velocity of the second electromagnetic wave is lower than that of the first electromagnetic wave, the power of the second electromagnetic wave is greater than that of the first electromagnetic wave, and the power of the second electron beam is less than that of the first electron beam.

[0029] In a possible implementation of the second aspect, each of the N1 first photonic crystal columns is not blocked by the N2 second photonic crystal columns in the first preset direction. The size of each of the N1 first photonic crystal columns is the same, and the size of each of the N2 second photonic crystal columns is the same.

[0030] In a possible implementation of the second aspect, the N1 first photonic crystal columns and the N2 second photonic crystal columns form N3 photonic crystal arrays on the first inner plane. The N3 photonic crystal arrays are arranged in sequence in the first preset direction. One photonic crystal array includes one first photonic crystal and at least two second photonic crystals. The at least two second photonic crystals are arranged in sequence on both sides of the one first photonic crystal. N3 is a positive integer greater than or equal to 1.

[0031] In a possible implementation of the second aspect, the photonic crystal array is an arc-shaped array in a third preset direction, and the opening direction of the arc-shaped array is the first preset direction, or the photonic crystal array is a straight-line array in a third preset direction. The third preset direction is perpendicular to the first preset direction and parallel to the first inner plane.

[0032] In conjunction with the second aspect, in one feasible implementation, the first photonic crystal pillar and the second photonic crystal pillar are rectangular pillars. The height of the first photonic crystal pillar in the second preset direction is equal to half the height of the second photonic crystal pillar in the second preset direction. The length of the first photonic crystal pillar in the first preset direction is equal to two-thirds the length of the second photonic crystal pillar in the first preset direction. The width of the first photonic crystal pillar in the third preset direction is equal to the width of the second photonic crystal pillar in the third preset direction.

[0033] In conjunction with the second aspect, in one feasible implementation, the first cavity further includes a second inner plane. The second inner plane is parallel to the first inner plane. The distance between the second inner plane and the first inner plane in the second preset direction is equal to the height of the second photonic crystal pillar in the second preset direction.

[0034] In conjunction with the second aspect, in one feasible implementation, the slow-wave circuit includes a slow-wave component and a first waveguide conversion component. The slow-wave component includes a first cavity and N1 first photonic crystal pillars and N2 second photonic crystal pillars disposed on a first inner plane of the first cavity. The first waveguide conversion component is connected to the slow-wave component. When the transmission mode of the first electromagnetic wave is a first transmission mode, the first waveguide conversion component can transmit the received first electron beam to the slow-wave component, convert the received source electromagnetic wave of the second transmission mode into the first electromagnetic wave, and transmit the first electromagnetic wave to the slow-wave component. The first transmission mode is different from the second transmission mode. Alternatively, the slow-wave component can convert the received first electromagnetic wave and the first electron beam into the second electromagnetic wave and the second electron beam and output them.

[0035] In conjunction with the second aspect, in one feasible implementation, the first waveguide conversion component includes a second cavity, the third inner plane of which is parallel to the first preset direction. N4 third photonic crystal pillars and N5 second photonic crystal pillars are disposed on the third inner plane. The N4 third photonic crystal pillars are arranged sequentially along the first preset direction, and the N5 second photonic crystal pillars are arranged sequentially on both sides of the N4 third photonic crystal pillars. The height of each of the N4 third photonic crystal pillars in the second preset direction increases sequentially in the first preset direction. The height of the tallest third photonic crystal pillar among the N4 third photonic crystal pillars in the second preset direction is equal to the height of the first photonic crystal pillar in the second preset direction. Each of the N5 second photonic crystal pillars has the same height in the second preset direction. N4 and N5 are positive integers greater than or equal to 2.

[0036] With reference to the second aspect, in a possible implementation of the second aspect, each of the N4 third photonic crystal columns is not blocked by the N5 second photonic crystal columns in the first preset direction.

[0037] With reference to the second aspect, in a possible implementation of the second aspect, a shape of the second cavity is determined by a transmission mode of the electromagnetic wave entering the first waveguide conversion component and a transmission mode of the electromagnetic wave output by the first waveguide conversion component.

[0038] With reference to the second aspect, in a possible implementation of the second aspect, the slow-wave circuit further includes a second waveguide conversion component connected to the slow-wave component. The second electron beam can be conducted and output through the second waveguide conversion component, and the second electromagnetic wave can be converted into a third electromagnetic wave of a third transmission mode through the second waveguide conversion component, and the third electromagnetic wave is output. The third transmission mode is different from the first transmission mode.

[0039] With reference to the second aspect, in a possible implementation of the second aspect, a third cavity is arranged in the second waveguide conversion component, and a fourth inner plane of the third cavity is parallel to the first preset direction. N6 fourth photonic crystal columns and N7 second photonic crystal columns are arranged on the fourth inner plane. The N6 fourth photonic crystal columns are arranged in sequence along the first preset direction, and the N7 second photonic crystal columns are arranged in sequence on both sides of the N6 fourth photonic crystal columns. The height of each fourth photonic crystal column in the N6 fourth photonic crystal columns in the second preset direction decreases in sequence in the first preset direction. The height of the fourth photonic crystal column with the maximum height in the N6 fourth photonic crystal columns in the second preset direction is equal to the height of the first photonic crystal column in the second preset direction. The height of each second photonic crystal column in the N7 second photonic crystal columns in the second preset direction is the same. N6 and N7 are positive integers greater than or equal to 2.

[0040] With reference to the second aspect, in a possible implementation of the second aspect, each of the N6 fourth photonic crystal columns is not blocked by the N7 second photonic crystal columns in the first preset direction.

[0041] With reference to the second aspect, in a possible implementation of the second aspect, a shape of the third cavity is determined by a transmission mode of the electromagnetic wave entering the second waveguide conversion component and a transmission mode of the electromagnetic wave output by the second waveguide conversion component.

[0042] In a possible implementation of the second aspect, the slow wave circuit further comprises a first electromagnetic interface and a second electromagnetic interface. The first electromagnetic interface is connected with the first waveguide conversion component and a first waveguide outside the slow wave circuit, and the second electromagnetic interface is connected with the second waveguide conversion component and a second waveguide outside the slow wave circuit. The first electromagnetic interface is internally provided with a first electron beam channel and a first electromagnetic wave channel, and the second electromagnetic interface is internally provided with a second electron beam channel and a second electromagnetic wave channel. Before the received first electron beam is transmitted to the slow wave component through the first waveguide conversion component and the received source electromagnetic wave of the second transmission mode is converted into the first electromagnetic wave of the first transmission mode, the first electron beam can be received from outside the slow wave circuit through the first electron beam channel and transmitted to the first waveguide conversion component. The source electromagnetic wave can also be received from the first waveguide outside the slow wave circuit through the first electromagnetic wave channel and transmitted to the first waveguide conversion component. Before the second electron beam is conducted and output through the second waveguide conversion component and the second electromagnetic wave is converted into a third electromagnetic wave of a third transmission mode through the second waveguide conversion component, the second electron beam can be received from the second waveguide conversion component through the second electron beam channel and transmitted to the outside of the slow wave circuit, and the third electromagnetic wave can also be received from the second waveguide conversion component through the second electromagnetic wave channel and transmitted to the second waveguide outside the slow wave circuit.

[0043] In a possible implementation of the second aspect, the first waveguide and the second waveguide are standard rectangular waveguides. The second cavity of the first waveguide conversion component and the third cavity of the second waveguide conversion component have a cross section parallel to the first preset direction and the third preset direction, which is an isosceles trapezoid. The length of a side of the cross section close to the slow wave component is smaller than the length of a side of the cross section close to the first electromagnetic interface and / or the second electromagnetic interface.

[0044] In a possible implementation of the second aspect, the first cavity has a cross section parallel to the first preset direction and the third preset direction, which is a rectangle.

[0045] In a possible implementation of the second aspect, the first cavity has a cross section parallel to the first preset direction and the third preset direction, which is a rectangle.

[0046] In a fourth aspect, the embodiments of the present application further provide an electromagnetic wave processing device. The electromagnetic wave processing device can include the traveling wave tube provided in the third aspect and a discrete device coupled to the traveling wave tube.

[0047] The schemes provided in the second aspect to the fourth aspect are used to implement or assist in implementing the slow wave circuit provided in the first aspect, and thus can achieve the same or corresponding beneficial effects as the first aspect, which will not be described here again.

[0048] In summary, the slow wave circuit and the electromagnetic wave processing method provided by the embodiments of the present application can improve the working bandwidth of the traveling wave tube and reduce the working voltage of the traveling wave tube, and can improve the applicability and practicability of the traveling wave tube in the terahertz wave band. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is a structural schematic diagram of a slow wave circuit provided by an embodiment of the present application;

[0050] Figure 2 is a sectional view of a slow wave circuit provided by an embodiment of the present application;

[0051] Figure 3 is a sectional view of a slow wave circuit provided by an embodiment of the present application;

[0052] Figure 4 is a sectional view of a slow wave circuit provided by an embodiment of the present application;

[0053] Figure 5 is a sectional view of a slow wave circuit provided by an embodiment of the present application;

[0054] Figure 6 is a performance simulation result diagram of a slow wave circuit provided by an embodiment of the present application;

[0055] Figure 7 is a sectional view of a slow wave circuit provided by an embodiment of the present application;

[0056] Figure 8 is a performance simulation result diagram of a slow wave circuit provided by an embodiment of the present application;

[0057] Figure 9 is a structural schematic diagram of a slow wave circuit provided by an embodiment of the present application;

[0058] Figure 10 is a structural schematic diagram of a first waveguide conversion component provided by an embodiment of the present application;

[0059] Figure 11 is a sectional view of a first waveguide conversion component provided by an embodiment of the present application;

[0060] Figure 12is a first waveguide conversion component provided by an embodiment of the present application, a cross-sectional view of the first waveguide conversion component;

[0061] Figure 13 is a slow wave circuit provided by an embodiment of the present application, a structure schematic diagram of the slow wave circuit;

[0062] Figure 14 is a second waveguide conversion component provided by an embodiment of the present application, a structure schematic diagram of the second waveguide conversion component;

[0063] Figure 15 is a second waveguide conversion component provided by an embodiment of the present application, a cross-sectional view of the second waveguide conversion component;

[0064] Figure 16 is a second waveguide conversion component provided by an embodiment of the present application, a cross-sectional view of the second waveguide conversion component;

[0065] Figure 17 is a slow wave circuit provided by an embodiment of the present application, a structure schematic diagram of the slow wave circuit;

[0066] Figure 18 is a slow wave circuit provided by an embodiment of the present application, a structure schematic diagram of the slow wave circuit;

[0067] Figure 19 is an electromagnetic wave processing method provided by an embodiment of the present application, a flowchart of the electromagnetic wave processing method;

[0068] Figure 20 is a traveling wave tube provided by an embodiment of the present application, a structure schematic diagram of the traveling wave tube. DETAILED DESCRIPTION

[0069] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings provided by the embodiments of the present application.

[0070] Compared with solid-state electronic devices, the traveling wave tube has outstanding advantages such as wide frequency band, high gain and long service life. Therefore, the traveling wave tube has been one of the main microwave amplifiers used in wireless communication systems such as satellite communication or radar. The so-called traveling wave tube refers to a kind of vacuum electronic device that can realize the amplification function by continuously modulating the speed of the electron beam. In the traveling wave tube, the electron beam interacts with the electromagnetic wave traveling in the slow wave circuit, and the electron beam can convert its kinetic energy to the electromagnetic wave, thereby completing the power amplification of the electromagnetic wave. As the core component of the traveling wave tube, the characteristics of the slow wave circuit can directly determine the performance of the traveling wave tube. For example, different structures of the slow wave circuit can make the operating voltage and operating bandwidth of the traveling wave tube different. In recent years, with the progress of processing technology and the proposal of various new structures of the slow wave circuit, the operating frequency of the traveling wave tube is developing towards the high frequency band (such as the terahertz band). With the development of the traveling wave tube towards the high frequency band, the size of the slow wave circuit is required to be smaller and smaller, and the reduction of the size will reduce the performance of the slow wave circuit, thereby limiting the application of the traveling wave tube in the terahertz band. Therefore, how to design a slow wave circuit with small size and high performance has become a research hotspot. In the existing scheme, the slow wave circuit based on the staggered double-gate structure loaded with photonic crystals or the folded waveguide structure loaded with photonic crystals is usually applied to the traveling wave tube in the terahertz band. However, these structures of the slow wave circuit all have problems such as narrow operating bandwidth, high operating voltage and high assembly precision requirement, which have a great influence on the performance of the traveling wave tube.

[0071] Therefore, the problem to be solved by the present application is to design a high-performance slow wave circuit to improve the bandwidth of the traveling wave tube using the slow wave circuit and reduce the operating voltage of the traveling wave tube, so as to improve the applicability and practicability of the traveling wave tube in the terahertz band.

[0072] Embodiment one

[0073] Please refer to Figure 1 , Figure 1 is a structure diagram of a slow wave circuit provided by an embodiment of the present application. As shown in Figure 1 , the slow wave circuit 01 can include a first shell 105, a first cavity 101 is arranged in the inside of the first shell 105, and the first cavity 101 includes a first inner plane 102. Here, for the convenience of description in the spatial structure, a three-dimensional spatial orientation coordinate system is introduced, which includes a first preset direction x, a second preset direction y and a third preset direction z. The first preset direction x is the direction in which the electron beam and the electromagnetic wave travel in the slow wave circuit 01, and the first preset direction x is parallel to the first inner plane 102. The second preset direction y is perpendicular to the first inner plane 102. The third preset direction z is parallel to the first inner plane 102 and perpendicular to the first preset direction x. It should be noted here that,Figure 1 The first shell 105 is actually split into a first slot base 1051 and a first cover plate 1052 for ease of understanding, and the inner bottom surface of the first slot base 1051 is the first inner plane 102. It should be understood that the first shell 105 can be integrally formed or composed of a separate base and a separate cover plate as shown in the actual implementation, and the structure of the first shell 105 is not limited in the present application. Figure 1 The cross section of the first cavity 101 parallel to the first preset direction x and the third preset direction z can be rectangular or other shapes, and the present application does not make specific limitations.

[0074] On the first inner plane 102, N1 first photonic crystal columns 103 and N2 second photonic crystal columns 104 are arranged. Here, N1 is a positive integer greater than or equal to 1, and N2 is a positive integer greater than or equal to 2. The N1 first photonic crystal columns 103 are arranged in the first preset direction on the first inner plane 102, and the N2 second photonic crystal columns 104 are arranged on both sides of the N1 first photonic crystal columns 103. In particular, each of the N1 first photonic crystal columns 103 is not blocked by the N2 second photonic crystal columns 104 in the first preset direction. For example, see Figure 2 Figure 2 is a cross-sectional view of a slow wave circuit provided by an embodiment of the present application. Here, Figure 2 is a cross section of the slow wave circuit 01 parallel to the first preset direction x and the third preset direction z. As shown in Figure 2 The N1 first photonic crystal columns 103 are arranged in a straight line in the first preset direction, forming a column of first photonic crystal columns in the first preset direction. With this column of first photonic crystal columns as a dividing line, N2 second photonic crystal columns 104 are arranged on both sides of the dividing line. Here, the N2 second photonic crystal columns 104 should be symmetrically arranged on both sides of the N1 first photonic crystal columns 103 and should not block any of the N1 first photonic crystal columns 103 in the first preset direction. As shown in Figure 2 ​As shown, N2 / 2 second photonic crystal columns 1042 are distributed on the left side of the N1 first photonic crystal columns 103, and the N2 / 2 second photonic crystal columns 1042 are arranged in two columns of second photonic crystal columns in the first preset direction, which are parallel to the column of first photonic crystal columns 103 formed by the N1 first photonic crystal columns 103 in the first preset direction. Similarly, N2 / 2 second photonic crystal columns 1041 are also distributed on the right side of the N1 first photonic crystal columns 103, and the N2 / 2 second photonic crystal columns 1041 are also arranged in two columns of second photonic crystal columns in the first preset direction, and the two columns of second photonic crystal columns are also parallel to the column of first photonic crystal columns 103 formed by the N1 first photonic crystal columns 103 in the first preset direction. It can be seen that the N2 / 2 second photonic crystal columns 1041 and the N2 / 2 second photonic crystal columns 1042 are symmetrical to each other in position with the N1 first photonic crystal columns 103 as the symmetry line. It should be noted here that Figure 2 The arrangement mode of the N2 second photonic crystal columns 104 is only exemplary, and in actual implementation, the N2 second photonic crystal columns 103 can also be symmetrically arranged in other forms on the two sides of the N1 first photonic crystal columns 103, and the present application does not make specific limitations thereto.

[0075] In addition, in terms of size, the height of each first photonic crystal column in the N1 first photonic crystal columns 103 in the second preset direction is smaller than the height of each second photonic crystal column in the N2 second photonic crystal columns 104 in the second preset direction. Optionally, the size of each first photonic crystal column in the N1 first photonic crystal columns 103 is completely the same, and the size of each second photonic crystal column in the N2 second photonic crystal columns 104 is also completely the same. It should be noted here that for the first photonic crystal column and the second photonic crystal column on the first plane, the present application only requires that the height of the first photonic crystal column in the second preset direction is smaller than the height of the second photonic crystal column in the second preset direction, and does not make strict requirements on the size of the first photonic crystal column and the second photonic crystal column in other directions (such as the first preset direction x and the third preset direction z). Exemplarily, please refer to Figure 3 Figure 3 is another cross-sectional view of the slow wave circuit provided by the embodiment of the present application. Figure 3 is a cross-sectional view of the slow wave circuit 01 parallel to the second preset direction y and the third preset direction z. As shown, Figure 3 Taking the first photonic crystal column 1031 and the second photonic crystal column 1043 as an example, the height of the first photonic crystal column 1031 in the second preset direction y is h1, and the height of the second photonic crystal column 1043 in the second preset direction y is h2, h1 should be smaller than h2. In terms of spatial position, as shown, Figure 3 ​As shown, because the height of the first photonic crystal column in the second preset direction y is less than the height of the second photonic crystal column in the second preset direction y, a space channel exists between the N1 first photonic crystal columns 103 and the first shell 105, which is a space for the electron beam and electromagnetic wave to pass through, and is the third electron beam channel in the first cavity 101 (here, for the sake of convenience, the third electron beam channel will be used in the following description).

[0076] In actual work, the first cavity 101 can receive the first electromagnetic wave and the first electron beam provided by the slow wave circuit 01, and constrain the first electromagnetic wave and the first electron beam to pass through the third electron beam channel. Optionally, the first electromagnetic wave is a terahertz electromagnetic wave. When the first electromagnetic wave and the first electron beam pass through the third electron beam channel, the N1 first photonic crystal columns 103 and the N2 second photonic crystal columns 104 can reduce the phase velocity of the first electromagnetic wave, and also amplify the power of the first electromagnetic wave based on the first electron beam, so that the first cavity 101 outputs a second electromagnetic wave and a second electron beam. Here, the phase velocity of the second electromagnetic wave is lower than that of the first electromagnetic wave, the power of the second electromagnetic wave is greater than that of the first electromagnetic wave, and the power of the second electron beam is less than that of the first electron beam. It should be noted that the N1 first photonic crystal columns 103 and the N2 second photonic crystal columns 104 form a special defect structure. Because the regularly arranged photonic crystal columns can reduce the phase velocity of the electromagnetic wave, this defect structure can effectively reduce the phase velocity of the first electromagnetic wave. In addition, this defect structure can make the transmission mode of the first electromagnetic wave have a strong longitudinal electric field component, so that the first electromagnetic wave can exchange energy with the first electron beam during transmission, and the kinetic energy of the first electron beam can be converted into the power of the first electromagnetic wave, thereby completing the power amplification of the first electromagnetic wave. Therefore, the slow wave circuit 01 can obtain the power-amplified second electromagnetic wave and the energy-decayed (i.e., power-reduced) second electron beam through the first cavity, the N1 first photonic crystal columns 103, and the N2 second photonic crystal columns 104.

[0077] In the above implementation, the first cavity and N1 first photonic crystal columns 103 and N2 second photonic crystal columns 104 regularly arranged on the first inner plane 102 of the first cavity are included in the slow wave circuit 01, and the N1 first photonic crystal columns 103 and the N2 second photonic crystal columns 104 form a special defect structure due to the difference in height. On the one hand, the defect structure composed of a plurality of regularly arranged photonic crystal columns can significantly reduce the phase velocity of the transmitted first electromagnetic wave in the first cavity 101, so that the first electromagnetic wave can be transmitted at a lower phase velocity in the first cavity 101, which can reduce the operating voltage requirement of the slow wave circuit 01 on the first electron beam. On the other hand, since the transmission mode supported by the first cavity 101 is a new transmission mode generated by the N1 first photonic crystal columns in the photonic crystal band gap, the mode will not be affected by the photonic crystal band gap, so that the slow wave circuit 01 can have a wider operating bandwidth. Since the slow wave circuit 01 with the above structure has a wider operating bandwidth and can interact with a lower voltage electron beam, the slow wave circuit 01 has a wide operating bandwidth and a low operating voltage. Therefore, by using such a slow wave circuit 01, the operating bandwidth of the traveling wave tube can be improved and the operating voltage of the traveling wave tube can be reduced, and the applicability and practicability of the traveling wave tube in the terahertz wave band can be improved.

[0078] Optionally, the first cavity 101 can further include a second inner plane, which is parallel to the first inner plane 102, and the distance between the second inner plane and the first inner plane 102 in the second preset direction y should be equal to the height of the second photonic crystal column on the first inner plane 101 in the second preset direction y. That is, in the first cavity 101, the two ends of the second photonic crystal column should be attached to the inner wall of the first cavity 101. Here, in combination with the structure of the first cavity 101 shown in FIG. 1, the second inner plane can be the inner surface of the first cover plate 1052 facing the first inner plane 101. Figure 1

[0079] In some possible implementations, the N1 first photonic crystal columns 103 and the N2 second photonic crystal columns 104 are arranged on the first inner plane 102 in the form of N3 photonic crystal arrays. N3 is a positive integer greater than or equal to 1. The structure of each photonic crystal array in the N3 photonic crystal arrays is the same. The N3 photonic crystal arrays are arranged in the first preset direction x on the first inner plane 102 in sequence. The distance between any two adjacent photonic crystal arrays in the N3 photonic crystal arrays in the first preset direction x is the same. Further, each photonic crystal array in the N3 photonic crystal arrays includes one first photonic crystal and at least two second photonic crystals, and the at least two second photonic crystals are arranged on the two sides of the one first photonic crystal in sequence. For details, please refer to​Figure 4 , Figure 4 This is another cross-sectional view of a slow-wave circuit provided in an embodiment of this application. Figure 4 It is the cross-section of the slow-wave circuit 01 parallel to the first preset direction x and the third preset direction z. For example... Figure 4 As shown, N1 first photonic crystal pillars 103 and N2 second photonic crystal pillars 104 form N3 identical photonic crystal arrays on the first inner plane 102. These N3 photonic crystal arrays are equidistantly arranged in a first predetermined direction x, and the distance between any two adjacent photonic crystal arrays in the first predetermined direction x is equal to L1. Here, L1 is a constant greater than 0. Since the structure of each photonic crystal array is identical, the specific structure of these N3 photonic crystal arrays will be described below using photonic crystal array 106 as an example. Figure 4 As shown, the photonic crystal array 106 includes a first photonic crystal pillar 1031 and second photonic crystal pillars 1043, 1044, 1045, and 1046. Specifically, in a first preset direction x, the second photonic crystal pillars 1043 and 1044 are arranged to the left of the first photonic crystal pillar 1031, and the second photonic crystal pillars 1045 and 1046 are arranged to the right of the first photonic crystal pillar 1031. Furthermore, the second photonic crystal pillars 1043 and 1044 are arranged symmetrically with respect to the first photonic crystal pillar 1031. In practical use, after the first electron beam and the first electromagnetic wave enter the first cavity 101, each of the above N3 photonic crystal arrays will reduce the phase velocity of the first electromagnetic wave and at the same time cause the first electron beam and the first electromagnetic wave to exchange capabilities to achieve power amplification of the first electromagnetic wave, so that the first cavity 101 can output the second electron beam and the second electromagnetic wave.

[0080] In the above implementation, N1 first photonic crystal pillars 103 and N2 second photonic crystal pillars 104 are arranged on the first inner plane 102 in the form of N3 photonic crystal arrays with the same structure. This makes the structure of the slow-wave circuit 01 more regular. On the one hand, this facilitates the design and production of the slow-wave circuit 01. On the other hand, the performance of the slow-wave circuit 01 can be flexibly adjusted by the number of photonic crystal arrays, thereby improving the functional flexibility of the slow-wave circuit 01.

[0081] In a first optional implementation, each of the N3 photonic crystal arrays can be an arc-shaped array in the third preset direction z. Furthermore, the opening direction of this arc-shaped array is the first preset direction x. For example, please refer to... Figure 4In the third preset direction z, one first photonic crystal and at least two second photonic crystals in each photonic crystal array are arranged in an arc-shaped array. In other words, the N1 first photonic crystal columns 103 and the N2 second photonic crystal columns 104 are arranged in a hexagonal lattice in the first preset direction x, and the lattice constant is L1. Taking the photonic crystal array 106 as an example, the second photonic crystal column 1043, the second photonic crystal column 1044, and the first photonic crystal column 1031 in the photonic crystal array 106 constitute an arc of the arc-shaped array, and the second photonic crystal column 1045, the second photonic crystal column 1046, and the first photonic crystal column 1031 constitute another arc of the arc-shaped array.

[0082] In the second optional implementation, each of the N3 photonic crystal arrays can be a linear array in the third preset direction z. In other words, one first photonic crystal column and at least two second photonic crystal columns in each photonic crystal array are arranged in a linear array in the third preset direction z. For example, referring to FIG. 1B, the photonic crystal array 107 is a linear array in the third preset direction z. Figure 5 Figure 5 is another cross-sectional view of the slow wave circuit provided by the embodiments of the present application. Here, Figure 5 is a cross section of the slow wave circuit 01 in which the photonic crystal array is a linear array, parallel to the second preset direction y and the third preset direction z. As shown in FIG. 1B, the photonic crystal array 107 is a linear array in the third preset direction z. Figure 5 In the third preset direction z, one first photonic crystal and at least two second photonic crystals in each photonic crystal array are arranged in a linear array. For example, taking the photonic crystal array 107 as an example, one first photonic crystal column and six second photonic crystal columns in the photonic crystal array 107 are arranged in a linear array in the third preset direction z. Here, it can also be understood that the N1 first photonic crystal columns 103 and the N2 second photonic crystal columns 104 are arranged in a square lattice in the first preset direction x, and the lattice constant is L1.

[0083] It should be noted that the arc-shaped or linear array is only an exemplary description of the structure of the photonic crystal array provided by the present application, and in actual implementation, the photonic crystal array can also be implemented by using other structures, which is not limited by the present application.

[0084] In the above implementation, each of the N3 photonic crystal arrays is arranged in an arc-shaped or linear array in the third preset direction z, which is simple in structure and easy to implement, and is convenient for the design and production of the slow wave circuit 01.

[0085] ​In some possible implementation manners, the first photonic crystal column and the second photonic crystal column on the first inner plane 102 are both rectangular columnar bodies. That is, the first photonic crystal column and the second photonic crystal column are both rectangular in the cross section parallel to the first preset direction x and the second preset direction y. In terms of size, the height of the first photonic crystal column in the second preset direction y is equal to half of the height of the second photonic crystal column in the second preset direction y, the length of the first photonic crystal column in the first preset direction x is equal to two-thirds of the length of the second photonic crystal column in the first preset direction x, and the width of the first photonic crystal column in the third preset direction z is equal to the width of the second photonic crystal column in the third preset direction z. It should be noted that the foregoing description of the size of the first photonic crystal column and the second photonic crystal column is applicable regardless of the array type of each photonic crystal array in the foregoing N3 photonic crystal arrays.

[0086] Because the size and the lattice constant of the first photonic crystal column and the second photonic crystal column on the first inner plane 102 are different when the photonic crystal array is in an arc shape or a straight line shape, the following will be described separately for the two different cases.

[0087] When the photonic crystal array in the slow wave circuit 01 is in an arc shape, please refer to Figure 3 and Figure 4 . Taking the first photonic crystal column 1031 and the second photonic crystal column 1044 in the photonic crystal array 106 as an example. Assuming that the length of the first photonic crystal column 1031 in the first preset direction x is a1, the width in the third preset direction z is b1, and the height in the second preset direction y is h1. Meanwhile, assuming that the length of the second photonic crystal column 1043 in the first preset direction x is a2, the width in the third preset direction z is b2, and the height in the second preset direction y is h2. Then, h1 = h2 / 2, a1 = 2 / 3a2, and b1 = b2.

[0088] Preferably, the lattice constant L1 can be 0.39 mm (millimeter), the length a2 and the width b2 can be 0.195 mm, the length a1 can be 0.13 mm, and the width b1 can be 0.195 mm. The height h2 can be 0.4 mm, and the height h1 can be 0.2 mm.

[0089] Please refer to Figure 6 , Figure 6 is a performance simulation result diagram of a slow wave circuit provided in the embodiments of the present application. When the photonic crystal array in the slow wave circuit 01 is in an arc shape and the foregoing specific size values are adopted, the simulation and experiment on the slow wave circuit 01 can obtain the result shown in Figure 6 . In the result, Figure 6(6-1) is a band gap characteristic diagram of the photonic crystal array in the slow wave circuit 01, Figure 6 (6-2) is a dispersion curve comparison diagram of the slow wave circuit 01, Figure 6 (6-3) is a diagram of the relationship between the frequency and the output power of the slow wave circuit 01. As shown in (6-1), curve 1 is the transverse electric mode (TE mode) passband of the slow wave circuit 01, and curve 2 is the transverse magnetic mode (TM mode) passband of the slow wave circuit 01. It can be seen from the diagram that the frequency band below 350 GHz is the first band gap of the slow wave circuit 01. The slow wave circuit 01 under the above structure utilizes the first band gap of the photonic crystal array, and introduces a TM mode in the band gap by constructing a suitable defect structure. As shown in (6-2), curve 3 is the dispersion curve of the TM mode introduced by the defect structure of the slow wave circuit 01, curve 4 is the dispersion curve of the TE mode passband of the slow wave circuit 01, and curve 5 is the dispersion curve of the electron beam with a speed of 0.25c (c is the speed of light). According to curves 3 and 4, it can be seen that there is an obvious forbidden band near the working frequency band of the slow wave circuit 01 and the TE mode passband cannot interact with the electron beam, so that the generation of self-oscillation effect near the working frequency band can be effectively suppressed. According to curves 3 and 5, it can be seen that the dispersion curve of the first electron beam overlaps with the dispersion curve of the TM mode in the phase range of 360° to 540°, indicating that the slow wave circuit 01 can interact with the electron beam with a speed of 0.25c, that is, the slow wave circuit 01 can work at a voltage of 16kV. As shown in (6-3), curve 6 is the output power curve of the slow wave circuit 01, and curve 7 is the corresponding gain curve. According to curves 6 and 7, it can be seen that the working frequency range of the slow wave circuit 01 is 210GHz to 240GHz, the bandwidth is up to 30GHz, and the output power is higher than 20W in the frequency range of 220GHz to 240GHz. From the above simulation results, it can be understood that the slow wave circuit 01 with the above-mentioned arc structure and size has a large working bandwidth and a small working voltage, which can significantly improve the working performance of the traveling wave tube using the slow wave circuit 01.

[0090] When the photonic crystal array in the slow wave circuit 01 adopts a linear structure, please refer to the above-mentioned Figure 5 and Figure 7 . Here, Figure 7 is another cross-sectional view of the slow wave circuit provided by the embodiment of the application. And, Figure 7The middle-slow-wave circuit 01 adopts the linear photonic crystal array as described above. Figure 7 is a cross-sectional view of the slow-wave circuit 01 parallel to the second preset direction y and the third preset direction z. Taking the first photonic crystal column 1071 and the second photonic crystal column 1072 in the photonic crystal array 107 as an example. It is assumed that the length of the first photonic crystal column 1071 in the first preset direction x is a3, the width in the third preset direction z is b3, and the height in the second preset direction y is h3. At the same time, it is assumed that the length of the second photonic crystal column 1072 in the first preset direction x is a4, the width in the third preset direction z is b4, and the height in the second preset direction y is h4. Then, h3 = h4 / 2, a3 = 2 / 3a4, b3 = b4.

[0091] Optionally, the above-mentioned lattice constant L1 can be 0.3mm (millimeter), the length a2 and the width b2 can be 0.15mm, the length a1 can be 0.1mm, and the width b1 can be 0.15mm. The height h2 can be 0.45mm, and the height h1 can be 0.225mm.

[0092] Please refer to the following Figure 8 , Figure 8 is another performance simulation result diagram of the slow-wave circuit provided by the embodiment of the present application. When the photonic crystal array in the slow-wave circuit 01 adopts a linear array and adopts the above-mentioned specific size values, the simulation simulation experiment is carried out for the slow-wave circuit 01, and the result shown in Figure 8 can be obtained. Figure 8 (8-1) in is the bandgap characteristic diagram of the slow-wave circuit 01, Figure 8 (8-2) in is the dispersion curve comparison diagram of the slow-wave circuit 01, Figure 8(8-3) is a schematic diagram of the relationship between the frequency and the output power of the slow wave circuit 01. As shown in (8-1), curve 1 is the TE mode passband of the slow wave circuit 01, and curve 2 is the TM mode passband of the slow wave circuit 01. From the results in the figure, it can be concluded that the first band gap of the slow wave circuit 01 is located in the frequency band below 300 GHz. The slow wave circuit 01 under the above structure utilizes the first band gap of the photonic crystal array, and by constructing a suitable defect structure, a TM mode is introduced in the band gap. As shown in (8-2), curve 3 is the dispersion curve of the TM mode introduced by the defect structure of the slow wave circuit 01, curve 4 is the dispersion curve of the TE mode passband of the slow wave circuit 01, and curve 5 is the dispersion curve of the electron beam with a speed of 0.182c (i.e., the speed of the first electron speed described above is 0.182c). As can be seen from curve 3 and curve 4, there is a clear band gap near the operating frequency band of the slow wave circuit 01 with the above structure and the TE mode passband that cannot interact with the electron beam, so as to effectively suppress the generation of self-oscillation effect near the operating frequency band. As can be seen from curve 3 and curve 5, the dispersion curve of the electron beam overlaps with the dispersion curve of the TM mode in the phase range of 360° to 540°, indicating that the slow wave circuit 01 can interact with the electron beam with a speed of 0.182c, that is, the slow wave circuit 01 can work at a voltage of 9.52kV. As shown in (8-3), curve 6 is the output power curve of the slow wave circuit 01, and curve 7 is the corresponding gain curve. According to curve 6 and curve 7, it can be seen that the operating frequency range of the slow wave circuit 01 is 210GHz to 230GHz, the bandwidth can reach 20GHz, and in the frequency range of 220GHz to 230GHz, the output power is higher than 6W. From the above simulation results, it can be understood that the slow wave circuit 01 with the straight line structure and the size described above has a large operating bandwidth and a small operating voltage, which can significantly improve the operating performance of the traveling wave tube using the slow wave circuit 01.

[0093] In some possible implementations, please refer to Figure 9 , Figure 9 is another structural schematic diagram of a slow wave circuit provided by the embodiments of the present application. As Figure 9As shown, the slow-wave circuit 01 can specifically include a slow-wave component 10 and a first waveguide conversion component 20. Here, the slow-wave component 10 can include the first cavity 101 in the first shell 105, the N1 first photonic crystal columns 103 and the N2 second photonic crystal columns 104 arranged on the first inner plane 102 of the first cavity 101. It can also be understood that the slow-wave circuit 01 described in the foregoing various implementation manners is actually the slow-wave component 10 described here, and in the present implementation manner, it is further described that the slow-wave circuit 01 includes the structure of the first waveguide conversion component 20 in addition to the slow-wave component 10. It should be noted that hereinafter, the structure of the first cavity 101 in the first shell 105, the N1 first photonic crystal columns 103 and the N2 second photonic crystal columns 104 arranged on the first inner plane 102 of the first cavity 101 described in the foregoing various implementation manners will be uniformly described as the slow-wave component 10. The first waveguide conversion component 20 is connected to the side of the slow-wave component 10 receiving the first electromagnetic wave and the first electron beam. It should be noted that the connection between the first waveguide conversion component 20 and the slow-wave component 10 can be direct connection or indirect connection through other devices, which is not specifically limited in the present application. It should be particularly noted that when the first waveguide conversion component 20 is directly connected to the slow-wave component 10, the first waveguide conversion component 20 and the slow-wave component 10 should be the same in the axial direction. Hereinafter, the specific structure and function of the first waveguide conversion component 20 will be described with the case that the first waveguide conversion component 20 is directly connected to the slow-wave component 10. For the convenience of description, it is assumed that the working mode supported by the slow-wave component 10 is the preset first transmission mode, that is, the transmission mode of the first electromagnetic wave is the first transmission mode.

[0094] In actual use, the first waveguide conversion component 20 can directly transmit the first electron beam received by it to the slow-wave component 10. At the same time, the first waveguide conversion component 20 can also convert the source electromagnetic wave of the second transmission mode received by it into the first electromagnetic wave of the first transmission mode supported by the slow-wave component 10, and transmit the converted first electromagnetic wave to the slow-wave component 10.

[0095] It should be noted that the transmission mode referred to in the embodiments of the present application can mainly include various TE modes and various TM modes. The first transmission mode and the second transmission mode are different. For example, the second transmission mode can be a TE mode, and the first transmission mode can be a TM mode. 10 It should be noted that the transmission mode referred to in the embodiments of the present application can mainly include various TE modes and various TM modes. The first transmission mode and the second transmission mode are different. For example, the second transmission mode can be a TE mode, and the first transmission mode can be a TM mode.

[0096] In the implementation, the slow-wave circuit 01 can amplify the electromagnetic wave of different transmission modes by converting the electromagnetic wave of the second transmission mode received by the slow-wave circuit 01 into the first electromagnetic wave of the first transmission mode supported by the slow-wave component 10, and the function flexibility and applicability of the slow-wave circuit 01 can be improved.

[0097] Further, in an optional implementation, referring to Figure 10 , Figure 10 is a structural schematic diagram of a first waveguide conversion component provided by an embodiment of the present application. As Figure 10 indicated, the first waveguide conversion component 20 can include a second housing 205, a second cavity 201 is arranged in the second housing 205, and the second cavity 201 has a third inner plane 202 parallel to the first preset direction x. In addition, the second cavity 201 is communicated with the first cavity 101 and is of the same axial direction. Here, for the convenience of spatial structure description, the three-dimensional spatial coordinate system described above is reused. The first preset direction x is also the direction of the electron beam and the electromagnetic wave in the first waveguide conversion component 20. It should be noted that Figure 10 is actually a structural section view of the first waveguide conversion component 20, for the convenience of understanding, the second housing 205 has been split into a second slot base 2051 and a second cover plate 2052, and the inner bottom surface of the second slot base 2051 is the third inner plane 202. It should be understood that in actual implementation, the second housing 205 can be an integrally formed structure, or can be formed by a separate base and a separate cover plate as Figure 10 indicated, and the present application does not make specific limitation thereon.

[0098] In addition, the third inner plane 202 is also provided with N4 third photonic crystal columns 203 and N5 second photonic crystal columns 204. Here, N4 and N5 are positive integers greater than or equal to 2. In the spatial position, similar to the slow-wave component 10, the N4 third photonic crystal columns 203 are arranged in the third plane 202 in the first preset direction x in sequence, and the N5 second photonic crystal columns 204 are arranged on both sides of the N4 third photonic crystal columns 203 in sequence. In addition, each of the N4 third photonic crystal columns 203 is not blocked by the N5 second photonic crystal columns 204 in the first preset direction x. For example, referring to Figure 11 , Figure 11 is a sectional view of the first waveguide conversion component provided by an embodiment of the present application. Here, Figure 11 is a sectional view of the first waveguide conversion component 20 parallel to the first preset direction x and the third preset direction z. As Figure 11As shown, the N4 third photonic crystal columns 203 are arranged in a straight line in the first preset direction x, thereby forming a column of third photonic crystal columns in the first preset direction x. With this column of third photonic crystal columns as a boundary, N5 second photonic crystal columns 204 are arranged on both sides of the boundary. Here, the N5 second photonic crystal columns 204 should be symmetrically arranged on both sides of the N4 third photonic crystal columns 203 and should not block any of the N4 third photonic crystal columns 203 in the first preset direction x. As shown, Figure 11 As shown, N5 / 2 second photonic crystal columns 2042 are distributed on the left side of the N4 third photonic crystal columns 203, and the N5 / 2 second photonic crystal columns 2042 are arranged into two columns of second photonic crystal columns in the first preset direction x. Similarly, N5 / 2 second photonic crystal columns 2041 are also distributed on the right side of the N4 third photonic crystal columns 203, and the N5 / 2 second photonic crystal columns 2041 are also arranged into two columns of second photonic crystal columns in the first preset direction x. The N5 / 2 second photonic crystal columns 2041 and the N5 / 2 second photonic crystal columns 2042 are symmetrically opposite to each other with the N4 third photonic crystal columns 203 as a symmetric line. It should be noted that, Figure 11 The arrangement of the N5 second photonic crystal columns 204 on both sides of the N4 third photonic crystal columns 203 is only exemplary, and in actual implementation, the N5 second photonic crystal columns 204 can also be symmetrically arranged on both sides of the N4 third photonic crystal columns 203 in other forms, which is not specifically limited in the present application. It should be further noted that, in actual implementation, similar to the slow wave component 10, the N4 third photonic crystal columns 203 and the N5 second photonic crystal columns 204 can also be arranged in the form of multiple identical photonic crystal arrays on the third inner plane 202, and each photonic crystal array in the multiple identical photonic crystal arrays can also be an arc-shaped array or a straight-line array in the third preset direction z.

[0099] In addition, in terms of size, the height of each of the N4 third photonic crystal columns 203 in the second preset direction y increases sequentially in the first preset direction x, and the third photonic crystal column with the largest height (i.e., the third photonic crystal column closest to the position at which the first waveguide conversion component 20 emits the first electromagnetic wave) among the N4 third photonic crystal columns 203 has a height in the second preset direction y equal to the height of the first photonic crystal column in the second preset direction y in the slow wave component 10. Similar to the N2 second photonic crystal columns 104 in the slow wave component 10, the heights of each of the N5 second photonic crystal columns 204 in the second preset direction y are also the same. It should be noted that the only difference between the third photonic crystal columns and the second photonic crystal columns in the first waveguide conversion component 20 is the height in the second preset direction y, and the sizes of the third photonic crystal columns and the second photonic crystal columns in other directions (such as the first preset direction x and the third preset direction z) are not strictly required. For details, see Figure 12 , Figure 12 is another cross-sectional view of the first waveguide conversion component provided in the embodiments of the present application. Here, Figure 12 is a cross section of the first waveguide conversion component 20 parallel to the second preset direction y and the first preset direction x. As Figure 12 indicated, the height of each of the N5 second photonic crystal columns 204 in the second preset direction y is h5. Figure 12 In the embodiment, it is assumed that the N4 third photonic crystal columns include a third photonic crystal column 2031, a third photonic crystal column 2032, a third photonic crystal column 2033, and a third photonic crystal column 2034, and the heights of the four third photonic crystal columns in the second preset direction y are h64, h63, h62, and h61, respectively, and satisfy the relationship h64>h63>h62>h61. The third photonic crystal column 2031 is the third photonic crystal column with the largest height among the N4 third photonic crystal columns, and the height of the third photonic crystal column 2031 is equal to the height of the first photonic crystal column in the slow wave component 10. Here, h5, h64, h63, h62, and h61 are all constants greater than 0.

[0100] In actual operation, the first waveguide conversion component 20 can receive a source electromagnetic wave of a second transmission mode and a first electron beam, and confine the source electromagnetic wave and the first electron beam to travel inside the first waveguide conversion component 20. When the source electromagnetic wave and the first electron beam travel inside the first waveguide conversion component 20, the first waveguide conversion component 20 can convert the source electromagnetic wave into a first electromagnetic wave of a first transmission mode through the height-graded defect structure composed of the N4 third photonic crystal columns 203 and the N5 second photonic crystal columns 204, without affecting the first electron beam transmitted therein.

[0101] Optionally, in actual implementation, the shape of the second cavity 201 can be determined by the transmission mode of the electromagnetic wave entering the first waveguide conversion component 20 and the transmission mode of the electromagnetic wave output from the first waveguide conversion component 20. For example, when the second transmission mode corresponding to the source electromagnetic wave is TE... 10 When the first transmission mode corresponding to the first electromagnetic wave is TM mode, the shape of the second cavity 201 can be a cavity with an equilateral trapezoidal cross-section, and the shorter base of the equilateral trapezoid is on the side of the first waveguide conversion component 30 facing the slow wave component 10. For details, please refer to [link to relevant documentation]. Figure 11 ,like Figure 11 As shown, the cross-section of the first waveguide conversion component 20 in both the third preset direction z and the first preset direction x is an equilateral trapezoid (that is, the third inner plane 202 is an equilateral trapezoid). It can be understood that when the transmission mode of the electromagnetic wave entering the first waveguide conversion component 20 and the transmission mode of the electromagnetic wave output by the first waveguide conversion component 20 are other types, the second cavity 201 can also be other shapes, such as a cuboid or a cube, etc. This application does not impose specific limitations on this.

[0102] Optionally, similar to the slow-wave component 10, the aforementioned second cavity 201 may further include a fifth inner plane. This fifth inner plane is parallel to the third inner plane 202, and the distance between the fifth inner plane and the third inner plane 202 in the second preset direction y should be equal to the height of the second photonic crystal pillar in the second preset direction y. That is, within the second cavity 201, both ends of each second photonic crystal pillar should be attached to the inner wall of the second cavity 201. Here, in conjunction with... Figure 12 The structure of the second cavity 201 shown above, the fifth inner plane can be the inner surface of the second cover plate 2052 facing the second plane 202.

[0103] In the above implementation, the first waveguide conversion component 20 is realized by arranging N4 third photonic crystal pillars 203 and N5 second photonic crystal pillars 204 on the third inner plane 202 of the second cavity 201. On the one hand, the first waveguide conversion component 20 has a simple structure and stable performance. On the other hand, the first waveguide conversion component 20 and the slow wave component 10 are structurally similar and have good compatibility.

[0104] For some feasible implementation methods, please refer to Figure 13 , Figure 13 This is another schematic diagram of a slow-wave circuit provided in an embodiment of this application. For example... Figure 13As shown, in addition to the aforementioned slow-wave component 10 and the first waveguide conversion component 20, the slow-wave circuit 01 may also include a second waveguide conversion component 30. This second waveguide conversion component 30 is connected to the side of the slow-wave component 10 that outputs the second electron beam and the second electromagnetic wave. Similar to the first waveguide conversion component 20, the connection between the second waveguide conversion component 30 and the slow-wave component 10 can be direct or indirect; this application does not impose specific limitations on this. Furthermore, when the second waveguide conversion component 30 is directly connected to the slow-wave component 10, the second waveguide conversion component 30 and the slow-wave component 10 should also be axially aligned. This can also be understood as meaning that when the first waveguide conversion component 20, the slow-wave component 10, and the second waveguide conversion component 30 are directly connected, all three should be on the same axis. The specific structure and function of the second waveguide conversion component 30 will be explained later using the case where the second waveguide conversion component 30 is directly connected to the slow-wave component 10. For ease of understanding, it is also assumed that the slow wave component 10 supports the preset first transmission mode, that is, the transmission mode of the first electromagnetic wave it receives and the transmission mode of the second electromagnetic wave it outputs are both the first transmission mode.

[0105] In practical use, the second waveguide conversion component 30 can directly output the received second electron beam. Simultaneously, the second waveguide conversion component 30 can also convert the second electromagnetic wave of the first transmission mode received from the slow-wave component 10 into a third electromagnetic wave of the third transmission mode, and output this third electromagnetic wave. Here, the third transmission mode is different from the second transmission mode. This third transmission mode can be the same as or different from the second transmission mode. For example, the second transmission mode can be TE... 10 The first transmission mode mentioned above can be TM mode, and the third transmission mode mentioned above can also be TE mode. 10 TM mode or other transmission modes besides TM mode.

[0106] In the above implementation, the first electromagnetic wave of the first transmission mode output by the slow wave component 10 is converted into a third electromagnetic wave of a different third transmission mode by the second waveguide conversion component 30 and then output. This enables the slow wave circuit 01 to output electromagnetic waves of different transmission modes after power amplification, which can further improve the functional flexibility and applicability of the slow wave circuit 01.

[0107] Furthermore, in one alternative implementation, please refer to... Figure 14 , Figure 14 This is a schematic diagram of the structure of a second waveguide conversion component provided in an embodiment of this application. Figure 14As shown, the second waveguide conversion component 30 can include a third shell 305, and a third cavity 301 is arranged in the third shell 305, and the third cavity 301 has a fourth inner plane 302 parallel to the first preset direction x. In addition, the third cavity 301 is communicated with the first cavity 101, and is in the same axial direction. Here, similar to the foregoing, for the convenience of description of the spatial structure, the three-dimensional spatial coordinate system described above is reused. Among them, the first preset direction x is also the direction of the electron beam and the electromagnetic wave in the second waveguide conversion component 30. It should be noted here that, similar to the foregoing, Figure 14 For the convenience of understanding, the third shell 305 has also been split into a third groove-shaped base 3051 and a third cover plate 3052, and the inner bottom surface of the third groove-shaped base 3051 is the fourth inner plane 302 described above. It should be understood here that, in actual implementation, the third shell 305 described above can be an integrally formed structure, or can be composed of a separate base and a separate cover plate as shown, and the present application does not make specific limitations on this. Figure 14

[0108] In addition, N6 fourth photonic crystal columns 303 and N7 second photonic crystal columns 304 are arranged on the fourth inner plane 302. Here, N6 and N7 are positive integers greater than or equal to 2. In the spatial position, similar to the first waveguide conversion component 20 described above, each of the N6 fourth photonic crystal columns 303 is arranged in the first preset direction x on the fourth plane 302, and the N7 second photonic crystal columns 304 are arranged on both sides of the N6 fourth photonic crystal columns 303. In addition, each of the N6 fourth photonic crystal columns 303 is not blocked by the N7 second photonic crystal columns 304 in the first preset direction x. For example, see Figure 15 , Figure 15 is a cross-sectional view of a second waveguide conversion component provided by an embodiment of the present application. Here, Figure 15 is a cross section of the second waveguide conversion component 30 parallel to the first preset direction x and the third preset direction z. As shown, Figure 15 As shown, the N6 fourth photonic crystal columns 303 are arranged in a straight line in the first preset direction x, thereby forming a column of fourth photonic crystal columns in the first preset direction x. And taking this column of fourth photonic crystal columns as a boundary line, N7 second photonic crystal columns 304 are arranged on both sides of the boundary line. Here, the N7 second photonic crystal columns 304 should be symmetrically arranged on both sides of the N6 third photonic crystal columns 303. For example, see Figure 15 ​As shown, N7 / 2 second photonic crystal columns 3042 are distributed on the left side of the above-mentioned N6 fourth photonic crystal columns 303, and the N7 / 2 second photonic crystal columns 3042 are arranged into two columns of second photonic crystal columns in the first preset direction x. Similarly, N7 / 2 second photonic crystal columns 3041 are also distributed on the right side of the above-mentioned N6 fourth photonic crystal columns, and the N7 / 2 second photonic crystal columns 3041 are also arranged into two columns of second photonic crystal columns in the first preset direction x. The N7 / 2 second photonic crystal columns 3041 and the N7 / 2 second photonic crystal columns 3042 are mutually symmetrical with the N4 third photonic crystal columns 303 as the symmetrical line. It should be noted that, Figure 15 The arrangement of the N7 second photonic crystal columns 304 on the two sides of the N6 fourth photonic crystal columns 303 is only exemplary, and in actual implementation, the N7 second photonic crystal columns 304 can also be arranged symmetrically in other forms on the two sides of the N6 fourth photonic crystal columns 303, which is not limited in the present application. It should be further noted that, in actual implementation, similar to the slow wave component 10, the N6 fourth photonic crystal columns 303 and the N7 second photonic crystal columns 304 can also be arranged in the form of multiple identical photonic crystal arrays on the fourth inner plane 302, and each photonic crystal array in the multiple identical photonic crystal arrays can also be an arc array or a linear array in the third preset direction z.

[0109] In addition, in terms of size, the height of each fourth photonic crystal column in the N6 fourth photonic crystal columns 303 in the second preset direction y is sequentially decreased in the first preset direction x. The height of the fourth photonic crystal column with the largest height in the N6 fourth photonic crystal columns 303 (i.e., the fourth photonic crystal column closest to the position where the second waveguide conversion component 30 receives the first electromagnetic wave) in the second preset direction y is equal to the height of the first photonic crystal column in the slow wave component 10 in the second preset direction y. Similar to the N2 second photonic crystal columns in the slow wave component 10, the height of each second photonic crystal column in the N7 second photonic crystal columns 304 in the second preset direction y is also the same. It should be noted that, the only difference between the fourth photonic crystal column and the second photonic crystal column in the second waveguide conversion component 30 is the height in the second preset direction, and the sizes of the fourth photonic crystal column and the second photonic crystal column in other directions (such as the first preset direction x and the third preset direction z) can be the same or different. For details, please refer to Figure 16 Figure 16 is another cross-sectional view of the second waveguide conversion component provided by an embodiment of the present application. Here, Figure 16 As shown, the cross section of the second waveguide conversion component 30 is parallel to the second preset direction y and the first preset direction x. As shown in FIG. 6, Figure 16 ​As shown, the height of each of the N7 second photonic crystal pillars 304 in the second preset direction y is h7. Figure 16 It is assumed that the aforementioned N6 fourth photonic crystal pillars include fourth photonic crystal pillars 3031, 3032, 3033, and 3034. The heights of these four fourth photonic crystal pillars in the second predetermined direction y are h84, h83, h82, and h81, respectively, and satisfy the relationship h84>h83>h82>h81. Among them, fourth photonic crystal pillar 3031 is the fourth photonic crystal pillar with the largest height among the aforementioned N6 fourth photonic crystal pillars 303, and the height of fourth photonic crystal pillar 3031 is equal to the height of the first photonic crystal pillar in the aforementioned slow-wave component 10. Here, h84, h83, h82, and h81 are all constants greater than 0.

[0110] In actual operation, the second waveguide conversion component 30 can receive the second electromagnetic wave and the second electron beam of the first transmission mode and constrain the second electromagnetic wave and the second electron beam to travel within it. When the second electromagnetic wave and the second electron beam travel within it, the second waveguide conversion component 30 can convert the second electromagnetic wave into a third electromagnetic wave of the third transmission mode through the highly graded defect structure formed by the aforementioned N6 fourth photonic crystal pillars 303 and N7 second photonic crystal pillars 304, without affecting the second electron beam transmitted therein.

[0111] Optionally, in actual implementation, similar to the first waveguide conversion component 20 described above, the shape of the third cavity 301 can also be determined by the transmission mode of the electromagnetic wave entering the second waveguide conversion component 30 and the transmission mode of the electromagnetic wave output by the second waveguide conversion component 30. For example, when the first transmission mode corresponding to the second electromagnetic wave is TM mode and the third transmission mode corresponding to the third electromagnetic wave is TE mode... 10 In this configuration, the third cavity 201 can be a cavity with an equilateral trapezoidal cross-section, and the shorter base of this trapezoid is on the side of the second waveguide conversion component 30 facing the slow-wave component 10. For details, please refer to [link to relevant documentation]. Figure 15 ,like Figure 15 As shown, the cross-section of the second waveguide conversion component 30 parallel to the third preset direction z and the first preset direction x is an equilateral trapezoid (that is, the fourth inner plane 302 is an equilateral trapezoid). It can be understood that when the transmission mode of the electromagnetic wave entering the second waveguide conversion component 30 and the transmission mode of the electromagnetic wave output by the second waveguide conversion component 30 are other types, the third cavity 201 can also be other shapes, such as a cuboid or a cube, etc. This application does not impose specific limitations on this.

[0112] Optionally, similar to the first waveguide conversion component 20, the third cavity 301 can also contain a sixth inner plane, which is parallel to the fourth inner plane 302, and the distance between the sixth inner plane and the fourth inner plane 302 in the second preset direction y should be equal to the height of the second photonic crystal column in the second preset direction y. That is, in the third cavity 301, the two ends of each second photonic crystal column should be attached to the inner wall of the third cavity 301. Here, in combination with the structure of the third cavity 301 shown in FIG. 3B, the sixth inner plane can be the inner surface of the third cover plate 3052 facing the fourth inner plane 302. Figure 16

[0113] It should be noted that when the second transmission mode and the third transmission mode are the same, the structures of the first waveguide conversion component 20 and the second waveguide conversion component 30 can be completely the same. In other words, the first waveguide conversion component 20 and the second waveguide conversion component 30 are two different use modes of a functional component. For this functional component, when the electromagnetic wave of the second transmission mode enters from its first axis (i.e., the first preset direction x as described above), the functional component can convert the electromagnetic wave of the second transmission mode into the electromagnetic wave of the first transmission mode and output. When the electromagnetic wave of the first transmission mode enters the functional component from the opposite direction of the first axis, the functional component can convert the electromagnetic wave of the first transmission mode into the electromagnetic wave of the second transmission mode and output.

[0114] In the above implementation, the second waveguide conversion component 30 is realized by arranging N6 third photonic crystal columns 303 and N7 second photonic crystal columns 304 on the fourth inner plane 302 of the third cavity 301. On the one hand, this can make the structure of the second waveguide conversion component 30 simple and stable in performance, and on the other hand, it can also make the second waveguide conversion component 30 similar in structure to the slow wave component 10, and good compatibility.

[0115] In some possible implementations, please refer to Figure 17 , Figure 17 is another structural schematic diagram of a slow wave circuit provided by the embodiment of the present application. As shown in FIG. 4B, the slow wave circuit comprises a slow wave component 10 and a second waveguide conversion component 30. Figure 17 ​As shown, the slow wave circuit 01 can further comprise a first electromagnetic interface 40 and a second electromagnetic interface 50. The first electromagnetic interface 40 is connected to the first waveguide conversion component 20 and the first waveguide 02 outside the slow wave circuit 01, and the second electromagnetic interface 50 is connected to the second waveguide conversion component 30 and the second waveguide 03 outside the slow wave circuit 01. In actual use, the first electromagnetic interface 40 can be used to receive the first electron beam and the source electromagnetic wave from the outside of the slow wave circuit 01 and transmit them to the first waveguide conversion component 20. The second electromagnetic interface 50 can be used to receive the third electromagnetic wave and the second electron beam from the second waveguide conversion component 30 and transmit them to the outside of the slow wave circuit 01.

[0116] Further, as shown, Figure 17 As shown, the first electromagnetic interface 40 is provided with a first electron beam channel 401 and a first electromagnetic wave channel 402. There is a certain overlapping area between the first electron beam channel 401 and the first electromagnetic wave channel 402. Here it should be noted that, Figure 17 As shown, the first electromagnetic interface 40 is provided with a first electron beam channel 401 and a first electromagnetic wave channel 402. There is a certain overlapping area between the first electron beam channel 401 and the first electromagnetic wave channel 402. Here it should be noted that,

[0117] In actual operation, the first electromagnetic interface 40 can receive the first electron beam from outside of the slow wave circuit 01 (such as an electron gun connected to the slow wave circuit 01) through the first electron beam channel 401 and transmit the first electron beam to the first waveguide conversion component 20. Meanwhile, the first electromagnetic interface 40 can also receive the source electromagnetic wave from the first waveguide 02 through the first electromagnetic wave channel 402 and transmit the source electromagnetic wave to the first waveguide conversion component 20. Here, the first waveguide 02 can receive the source electromagnetic wave from a preset electromagnetic wave generator and transmit the source electromagnetic wave to the first electromagnetic wave channel 402. The second electromagnetic interface 50 can receive the second electron beam from the second waveguide conversion component 30 through the second electron beam channel 501 and transmit the second electron beam to outside of the slow wave circuit 01. Meanwhile, the second electromagnetic interface 50 can also receive the third electromagnetic wave from the second waveguide conversion component 30 through the second electromagnetic wave channel 502 and transmit the third electromagnetic wave to the second waveguide 03. Here, the second waveguide 03 can transmit the received third electromagnetic wave to other devices connected thereto, so that the devices can use the third electromagnetic wave.

[0118] It should be noted that the first photonic crystal column, the second photonic crystal column, the third photonic crystal column and the fourth photonic crystal column described above can be one-dimensional photonic crystal columns, two-dimensional photonic crystal columns, three-dimensional photonic crystal columns or other forms of photonic crystal columns that can be realized in the future, and the present application does not limit the same. The materials of the various photonic crystal columns, the slow wave component 10, the first waveguide conversion component 20, the second waveguide conversion component 30, the first electromagnetic interface 40 and the second electromagnetic interface 50 described above can be various metals such as copper, gold, etc., and the present application does not limit the same.

[0119] It should be noted that in the foregoing description, the slow wave component 10, the first waveguide conversion component 20, the second waveguide conversion component 30, the first electromagnetic interface 40 and the second electromagnetic interface 50 in the slow wave circuit 01 are all independent discrete devices. In actual implementation, the slow wave component 10, the first waveguide conversion component 20, the second waveguide conversion component 30, the first electromagnetic interface 40 and the second electromagnetic interface 50 can also be an integrally formed structure, and the above components are different functional partitions of the integrally formed structure. Specifically, the grooved structures corresponding to the slow wave component 10, the first waveguide conversion component 20, the second waveguide conversion component 30, the first electromagnetic interface 40 and the second electromagnetic interface 50 can be etched on a bottom plate, and then a cover plate can be used to close the etched bottom plate, thereby forming a complete slow wave circuit 01. For example, please refer to Figure 18 , Figure 18 is another structural schematic diagram of a slow wave circuit provided by the embodiment of the present application. Figure 18Figure 1 shows an etched backplane 181 and a cover plate 182 that can cover the etched backplane 181. On the backplane 181, there are grooves corresponding to the slow wave component 10, the first waveguide conversion component 20, the second waveguide conversion component 30, the first electromagnetic interface 40 and the second electromagnetic interface 50. When the cover plate 182 is closed with the etched backplane 181, there are five functional areas corresponding to the five functional components, i.e., the slow wave component 10, the first waveguide conversion component 20, the second waveguide conversion component 30, the first electromagnetic interface 40 and the second electromagnetic interface 50.

[0120] It should be noted that the description of the direction of the electromagnetic wave and the electron beam in the embodiments of the present application is for the purpose of clearly describing the structure and function of the components and should not be construed as a limitation on the components themselves.

[0121] The embodiment of the present application provides a slow wave circuit 01 comprising a slow wave component 10. The slow wave component 10 is composed of N1 first photonic crystal columns and N2 second photonic crystal columns arranged regularly on a first inner plane 102 and having different heights. The N1 first photonic crystal columns and the N2 second photonic crystal columns form a special defect structure due to the different heights. On the one hand, the defect structure composed of the regularly arranged photonic crystal columns can significantly reduce the phase velocity of the transmitted first electromagnetic wave in the slow wave component, so that the first electromagnetic wave can be transmitted at a lower phase velocity in the slow wave component 10, which can reduce the operating voltage requirement of the slow wave component 10 on the first electron beam. On the other hand, the transmission mode of the slow wave component 10 is a new transmission mode generated by the N1 first photonic crystal columns in the photonic crystal band gap, so that the mode is not affected by the photonic crystal band gap, thereby making the slow wave component 10 have a wider operating bandwidth. Since the slow wave component 10 with the above structure has a wider operating bandwidth and can interact with a lower voltage electron beam, the operating bandwidth of the slow wave circuit 01 is large and the operating voltage is small, which can improve the operating bandwidth of the traveling wave tube using the slow wave circuit 10 and reduce the operating voltage of the traveling wave tube, and can improve the applicability and practicability of the traveling wave tube in the terahertz wave band.

[0122] Embodiment Two

[0123] Please refer to Figure 19 , Figure 19 is a flowchart of an electromagnetic wave processing method provided by the embodiment of the present application. The electromagnetic wave processing method is applicable to the slow wave circuit 01 described in embodiment one. In this embodiment, the specific structure and function of the slow wave circuit 01 can be referred to the corresponding description in the foregoing embodiment one, and this embodiment will not be described again. As shown in Figure 19As shown, the electromagnetic wave processing method can specifically include the following steps:

[0124] S191, receiving the first electromagnetic wave and the first electron beam through the first cavity.

[0125] In some possible implementation manners, the first cavity 101 in the slow wave circuit 01 can receive the first electromagnetic wave and the first electron beam. Here, the first electromagnetic wave is an electromagnetic wave in the terahertz frequency band. Here, the description of the first cavity 101, i.e., the internal structure thereof, can be referred to the corresponding description in the foregoing embodiment one, and thus will not be repeated here.

[0126] In an optional implementation manner, in the case where the slow wave circuit 01 contains multiple functional components, the slow wave circuit 01 can specifically include the slow wave component 10 and the first waveguide conversion component 20. It should be noted that, in the case where the slow wave circuit 01 contains multiple components, the structure composed of the first cavity 101 in the first shell 105, the N1 first photonic crystal columns 103 and the N2 second photonic crystal columns 104 arranged on the first inner plane 102 of the first cavity 101 will be uniformly described as the slow wave component 10, and the slow wave component 10 is also used to implement corresponding functions. In addition to the slow wave component 10, the slow wave circuit 01 can also contain the structure of the first waveguide conversion component 20. In the following, for the convenience of understanding and description, the structure composed of the first cavity 101 in the first shell 105, the N1 first photonic crystal columns 103 and the N2 second photonic crystal columns 104 arranged on the first inner plane 102 of the first cavity 101 will be uniformly described as the slow wave component 10. The first waveguide conversion component 20 is connected with the slow wave component 10. Here, the description of the structure of the first waveguide conversion component 20 can be referred to the corresponding description in the foregoing embodiment one, and thus will not be repeated here. In specific implementation, before the second electron beam and the second electromagnetic wave are generated and output through the slow wave component 10, the slow wave circuit 01 can directly transmit the received first electron beam to the slow wave component 10 through the first waveguide conversion component 20. At the same time, the slow wave circuit 01 can also convert the received second transmission mode source electromagnetic wave into the first electromagnetic wave in the first transmission mode supported by the slow wave component 10 through the first waveguide conversion component 20, and transmit the converted first electromagnetic wave to the slow wave component 10. The specific process can be referred to the description of the function of the first waveguide conversion component 20 in the foregoing embodiment one, and thus will not be repeated here.

[0127] In another alternative implementation, the slow-wave circuit 01 can further comprise a first electromagnetic interface 40, and the slow-wave circuit 01 can further be connected with a first waveguide 02. The first electromagnetic interface 40 can comprise a first electron beam channel 401 and a first electromagnetic wave channel 402. Here, the structure of the first electromagnetic interface 40 and the first waveguide 02 can refer to the corresponding description in the first embodiment, and thus will not be repeated here.

[0128] In a specific implementation, before the first waveguide conversion component 20 provides the first electron beam and the first electromagnetic wave for the slow-wave component 10, the slow-wave circuit 01 can receive the first electron beam from the outside (such as an electron gun connected with the slow-wave circuit 01) through the first electron beam channel 401 of the first electromagnetic interface 40 and transmit the first electron beam to the first waveguide conversion component 20. At the same time, the slow-wave circuit 01 can also receive the source electromagnetic wave from the first waveguide 02 through the first electromagnetic wave channel 402 of the first electromagnetic interface 40 and transmit the source electromagnetic wave to the first waveguide conversion component 20. Here, the first waveguide 02 can receive the source electromagnetic wave from a preset electromagnetic wave generator and transmit it to the first electromagnetic wave channel 402.

[0129] S192, power-amplify the first electromagnetic wave based on the first electron beam while reducing the phase velocity of the first electromagnetic wave by the N1 first photonic crystal columns and the N2 second photonic crystal columns, so that the first cavity outputs a second electromagnetic wave and a second electron beam.

[0130] In some possible implementations, after the slow-wave circuit 01 receives the first electromagnetic wave and the first electron beam through the slow-wave component 10, the slow-wave circuit 01 can power-amplify the first electromagnetic wave based on the first electron beam while reducing the phase velocity of the first electromagnetic wave by the N1 first photonic crystal columns and the N2 second photonic crystal columns in the slow-wave component 10, so that the first cavity 101 in the slow-wave component 10 outputs a second electromagnetic wave and a second electron beam. Here, the phase velocity of the second electromagnetic wave is lower than that of the first electromagnetic wave, the power of the second electromagnetic wave is greater than that of the first electromagnetic wave, and the power of the second electron beam is less than that of the first electron beam. Here, the specific process of obtaining and outputting the second electromagnetic wave and the second electron beam by the slow-wave component 10 can refer to the description of the function of the slow-wave component 10 in the first embodiment, and thus will not be repeated here.

[0131] In an alternative implementation, the slow-wave circuit 01 can further comprise a second waveguide conversion component 30. The second waveguide conversion component 30 is connected with the slow-wave component 10. Here, the structure of the second waveguide conversion component 30 can refer to the corresponding description in the first embodiment, and thus will not be repeated here.

[0132] In a specific implementation, after the second electron beam and the second electromagnetic wave are output by the slow wave component 10, the slow wave circuit 01 can output the second electron beam received from the slow wave component 10 directly through the second waveguide conversion component 30. At the same time, the slow wave circuit 01 can also convert the second electromagnetic wave of the first transmission mode received from the slow wave component 10 into a third electromagnetic wave of a third transmission mode through the second waveguide conversion component 30, and output the third electromagnetic wave. The specific process can be referred to the description of the function of the second waveguide conversion component 30 in the first embodiment above, and will not be repeated here. Here, the third transmission mode described above is different from the second transmission mode. The third transmission mode can be the same as or different from the second transmission mode described above.

[0133] In an optional implementation, the slow wave circuit 01 can further include a second electromagnetic interface 50, and the slow wave circuit 01 is further connected with a second waveguide 03. The second electromagnetic interface 50 is provided with a second electron beam channel 501 and a second electromagnetic wave channel 502. The structure of the second electromagnetic interface 50 and the second waveguide 03 can be referred to the corresponding description in the first embodiment above, and will not be repeated here.

[0134] In a specific implementation, the slow wave circuit 01 can receive the second electron beam from the second waveguide conversion component 30 through the second electron beam channel 501 of the second electromagnetic interface 50 and transmit the second electron beam to the outside of the slow wave circuit 01. At the same time, the slow wave circuit 01 can also receive the third electromagnetic wave from the second waveguide conversion component 30 through the second electromagnetic wave channel 502 of the second electromagnetic interface 50, and transmit the third electromagnetic wave to the second waveguide 03. Here, the second waveguide 03 can transmit the received third electromagnetic wave to other devices connected thereto, so that these devices can use the third electromagnetic wave. The specific process can be referred to the description of the function of the second electromagnetic interface 50 and the second waveguide 03 in the first embodiment above, and will not be repeated here.

[0135] In the embodiments of the present application, the slow-wave circuit 01 can complete power amplification of electromagnetic waves in the terahertz wave band through the slow-wave component 10 and other components. The slow-wave component 10 is a slow-wave component 10 composed of N1 first photonic crystal columns and N2 second photonic crystal columns regularly arranged on the first inner plane 102 and having different heights, and the different heights make the N1 first photonic crystal columns and the N2 second photonic crystal columns form a special defect structure. On the one hand, the defect structure can enable the first electromagnetic wave to be transmitted in the first cavity 101 at a lower phase velocity, which can reduce the requirement of the slow-wave circuit 01 on the operating voltage of the first electron beam. On the other hand, the defect structure can also make the mode not be affected by the photonic band gap, so that the slow-wave circuit 01 can have a wider operating bandwidth. Since the slow-wave circuit with the above structure has a wider operating bandwidth and can interact with an electron beam with a lower voltage, the slow-wave circuit 01 can have a wide operating bandwidth and a low operating voltage. Therefore, by using the slow-wave circuit 01 provided in the present application, the operating bandwidth of the traveling wave tube can be improved and the operating voltage of the traveling wave tube can be reduced, and the applicability and practicability of the traveling wave tube in the terahertz wave band can be improved.

[0136] The embodiments of the present application further provide a traveling wave tube. Please refer to Figure 20 , Figure 20 is a structural schematic diagram of a traveling wave tube provided in the embodiments of the present application. As shown in Figure 20 , the traveling wave tube 200 can include the slow-wave circuit 01 as described above, and an electron gun 2001, a magnetic focusing system 2002 and a collector 2003 coupled to the slow-wave circuit 01. In actual use, the electron gun 2001 is used to generate and inject a first electron beam into the slow-wave circuit 01, the magnetic focusing system 2002 is used to keep the first electron beam from changing shape during the process of passing through the slow-wave circuit 01, and the collector 2003 is used to receive a second electron beam output by the slow-wave circuit 01.

[0137] The embodiments of the present application further provide an electromagnetic wave processing device. The electromagnetic wave processing device includes the traveling wave tube 200 as described above, and various discrete devices coupled to the traveling wave tube 200. In actual use, the electromagnetic wave processing device can at least complete power amplification of electromagnetic waves in the terahertz wave band through the traveling wave tube 200.

[0138] The specific embodiments described above are further detailed descriptions of the purposes, technical solutions and beneficial effects of the present application, and it should be understood that the above descriptions are only specific embodiments of the present application and are not used to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, etc. made on the basis of the technical solutions of the present application shall be included in the protection scope of the present application.

Claims

1. A slow wave circuit, characterized by, The slow-wave circuit comprises a first cavity and N1 first photonic crystal columns and N2 second photonic crystal columns arranged on a first inner plane of the first cavity. The N1 first photonic crystal columns are arranged in a first preset direction, the N2 second photonic crystal columns are arranged on both sides of the N1 first photonic crystal columns in a second preset direction, a height of the first photonic crystal column in the second preset direction is less than a height of the second photonic crystal column in the second preset direction, the first preset direction is a direction of travel of an electromagnetic wave and an electron beam in the first cavity, the second preset direction is perpendicular to the first inner plane, N1 is a positive integer greater than or equal to 1, and N2 is a positive integer greater than or equal to 2.

2. The slow wave circuit of claim 1, wherein, The N1 first photonic crystal columns and the N2 second photonic crystal columns form N3 photonic crystal arrays on the first inner plane, the N3 photonic crystal arrays are arranged in the first preset direction, one photonic crystal array comprises one first photonic crystal and at least two second photonic crystals, and the at least two second photonic crystals are arranged on both sides of the one first photonic crystal in the second preset direction, and N3 is a positive integer greater than or equal to 1.

3. The slow wave circuit of claim 2, wherein, The photonic crystal array is an arc-shaped array in a third preset direction, or the photonic crystal array is a linear array in the third preset direction. The third preset direction is perpendicular to the first preset direction and parallel to the first inner plane.

4. The slow wave circuit of claim 3, wherein, The first photonic crystal column and the second photonic crystal column are rectangular columns, a height of the first photonic crystal column in the second preset direction is equal to half of a height of the second photonic crystal column in the second preset direction, a length of the first photonic crystal column in the first preset direction is equal to two-thirds of a length of the second photonic crystal column in the first preset direction, and a width of the first photonic crystal column in the third preset direction is equal to a width of the second photonic crystal column in the third preset direction.

5. The slow wave circuit according to any one of claims 1 to 4, characterized in that, The first cavity further comprises a second inner plane, the second inner plane is parallel to the first inner plane, and a distance between the second inner plane and the first inner plane in the second preset direction is equal to the height of the second photonic crystal column in the second preset direction.

6. The slow wave circuit according to any one of claims 1 to 4, characterized in that The slow-wave circuit comprises a slow-wave component and a first waveguide conversion component, the slow-wave component comprises the first cavity and the N1 first photonic crystal columns and the N2 second photonic crystal columns arranged on the first inner plane of the first cavity, and the first waveguide conversion component is connected with the slow-wave component.

7. The slow wave circuit of claim 6, wherein, The first waveguide conversion component is provided with a second cavity, a third inner plane of the second cavity is parallel to the first preset direction, and the third inner plane is provided with N4 third photonic crystal columns and N5 second photonic crystal columns. The N4 third photonic crystal columns are arranged in sequence along the first preset direction, the N5 second photonic crystal columns are arranged in sequence on both sides of the N4 third photonic crystal columns, the height of each third photonic crystal column in the N4 third photonic crystal columns in the second preset direction increases in sequence in the first preset direction, the height of the third photonic crystal column with the largest height in the N4 third photonic crystal columns in the second preset direction is equal to the height of the first photonic crystal column in the second preset direction, the height of each second photonic crystal column in the N5 second photonic crystal columns in the second preset direction is the same, N4 and N5 are positive integers greater than or equal to 2.

8. The slow wave circuit of claim 7, wherein, The slow-wave circuit further comprises a second waveguide conversion component connected with the slow-wave component.

9. The slow wave circuit of claim 8, wherein, The third cavity is provided in the second waveguide conversion component, a fourth inner plane of the third cavity is parallel to the first preset direction, and N6 fourth photonic crystal columns and N7 second photonic crystal columns are arranged on the fourth inner plane. The N6 fourth photonic crystal columns are arranged in sequence along the first preset direction, the N7 second photonic crystal columns are arranged in sequence on both sides of the N6 fourth photonic crystal columns, the height of each fourth photonic crystal column in the N6 fourth photonic crystal columns in the second preset direction decreases in sequence in the first preset direction, the height of the fourth photonic crystal column with the largest height in the N6 fourth photonic crystal columns in the second preset direction is equal to the height of the first photonic crystal column in the second preset direction, the height of each second photonic crystal column in the N7 second photonic crystal columns in the second preset direction is the same, N6 and N7 are positive integers greater than or equal to 2.

10. The slow wave circuit of claim 9, wherein, The slow-wave circuit further comprises a first electromagnetic interface and a second electromagnetic interface, the first electromagnetic interface is connected with the first waveguide conversion component and a first waveguide connected with the slow-wave circuit, the second electromagnetic interface is connected with the second waveguide conversion component and a second waveguide connected with the slow-wave circuit, the first electromagnetic interface is provided with a first electron beam channel and a first electromagnetic wave channel, and the second electromagnetic interface is provided with a second electron beam channel and a second electromagnetic wave channel.

11. A method of electromagnetic wave treatment, characterized by, The method is applied to a slow-wave circuit, and the slow-wave circuit comprises a first cavity, and N1 first photonic crystal columns and N2 second photonic crystal columns arranged on a first inner plane of the first cavity, wherein the N1 first photonic crystal columns are arranged in sequence along a first preset direction, and the N2 second photonic crystal columns are arranged in sequence on both sides of the N1 first photonic crystal columns, the height of the first photonic crystal column in a second preset direction is less than the height of the second photonic crystal column in the second preset direction, the first preset direction is the direction of movement of an electromagnetic wave and an electron beam in the first cavity, the second preset direction is perpendicular to the first inner plane, N1 is a positive integer greater than or equal to 1, and N2 is a positive integer greater than or equal to 2. The method comprises: receive and transmit a first electromagnetic wave and a first electron beam through the first cavity; amplify the first electromagnetic wave based on the first electron beam while reducing a phase velocity of the first electromagnetic wave through the N1 first photonic crystal columns and the N2 second photonic crystal columns, so that the first cavity outputs a second electromagnetic wave and a second electron beam, wherein the phase velocity of the second electromagnetic wave is lower than the phase velocity of the first electromagnetic wave, the power of the second electromagnetic wave is greater than the power of the first electromagnetic wave, and the power of the second electron beam is less than the power of the first electron beam.

12. The method of claim 11, wherein, The N1 first photonic crystal columns and the N2 second photonic crystal columns form N3 photonic crystal arrays on the first inner plane, the N3 photonic crystal arrays are arranged in the first preset direction in sequence, one photonic crystal array includes one first photonic crystal and at least two second photonic crystals, and the at least two second photonic crystals are arranged in sequence on both sides of the one first photonic crystal, wherein N3 is a positive integer greater than or equal to 1.

13. The method of claim 12, wherein, The photonic crystal array is an arc array in a third preset direction, and the opening direction of the arc array is the first preset direction, or the photonic crystal array is a linear array in the third preset direction. The third preset direction is perpendicular to the first preset direction and parallel to the first inner plane.

14. The method of claim 13, wherein, The first photonic crystal column and the second photonic crystal column are rectangular columns, the height of the first photonic crystal column in the second preset direction is equal to half of the height of the second photonic crystal column in the second preset direction, the length of the first photonic crystal column in the first preset direction is equal to two-thirds of the length of the second photonic crystal column in the first preset direction, and the width of the first photonic crystal column in the third preset direction is equal to the width of the second photonic crystal column in the third preset direction.

15. The method according to any one of claims 11-14, characterized in that, The first cavity further includes a second inner plane, the second inner plane is parallel to the first inner plane, and the distance between the second inner plane and the first inner plane in the second preset direction is equal to the height of the second photonic crystal column in the second preset direction.

16. The method according to any one of claims 11-14, characterized in that, The transmission mode of the first electromagnetic wave is a first transmission mode, the slow wave circuit includes a slow wave component and a first waveguide conversion component, the slow wave component includes the first cavity, N1 first photonic crystal columns and N2 second photonic crystal columns arranged on the first inner plane of the first cavity, and the first waveguide conversion component is connected with the slow wave component. The method further includes: transmitting the received first electron beam to the first cavity in the slow wave component through the first waveguide conversion component, converting the received source electromagnetic wave of a second transmission mode into a first electromagnetic wave of the first transmission mode, and transmitting the first electromagnetic wave to the first cavity in the slow wave component, wherein the first transmission mode is different from the second transmission mode.

17. The method of claim 16, wherein, The first waveguide conversion component is internally provided with a second cavity, a third inner plane of the second cavity is parallel to the first preset direction, and N4 third photonic crystal columns and N5 second photonic crystal columns are arranged on the third inner plane; The N4 third photonic crystal columns are sequentially arranged along the first preset direction, the N5 second photonic crystal columns are sequentially arranged on both sides of the N4 third photonic crystal columns, the height of each third photonic crystal column in the N4 third photonic crystal columns in the second preset direction sequentially increases in the first preset direction, the height of the third photonic crystal column with the maximum height in the N4 third photonic crystal columns in the second preset direction is equal to the height of the first photonic crystal column in the second preset direction, the height of each second photonic crystal column in the N5 second photonic crystal columns in the second preset direction is the same, and N4 and N5 are positive integers greater than or equal to 2.

18. The method of claim 17, wherein, The slow wave circuit further comprises a second waveguide conversion component connected with the slow wave component; The method further comprises: The second waveguide conversion component is internally provided with a third cavity, a fourth inner plane of the third cavity is parallel to the first preset direction, and N6 fourth photonic crystal columns and N7 second photonic crystal columns are arranged on the fourth inner plane; 19. The method of claim 18, wherein, The N6 fourth photonic crystal columns are sequentially arranged along the first preset direction, the N7 second photonic crystal columns are sequentially arranged on both sides of the N6 fourth photonic crystal columns, the height of each fourth photonic crystal column in the N6 fourth photonic crystal columns in the second preset direction sequentially decreases in the first preset direction, the height of the fourth photonic crystal column with the maximum height in the N6 fourth photonic crystal columns in the second preset direction is equal to the height of the first photonic crystal column in the second preset direction, the height of each second photonic crystal column in the N7 second photonic crystal columns in the second preset direction is the same, and N6 and N7 are positive integers greater than or equal to 2. The slow wave circuit further comprises a first electromagnetic interface and a second electromagnetic interface, the first electromagnetic interface is connected with the first waveguide conversion component and a first waveguide externally connected with the slow wave circuit, the second electromagnetic interface is connected with the second waveguide conversion component and a second waveguide externally connected with the slow wave circuit, the first electromagnetic interface is internally provided with a first electron beam channel and a first electromagnetic wave channel, and the second electromagnetic interface is internally provided with a second electron beam channel and a second electromagnetic wave channel; 20. The method of claim 19, wherein, Before the first waveguide conversion component is used to transmit the received first electron beam to the slow wave component and convert the received source electromagnetic wave in the second transmission mode into the first electromagnetic wave in the first transmission mode, the method further comprises: ​ receiving the first electron beam from outside of the slow wave circuit through the first electron beam channel and transmitting the first electron beam to the first waveguide conversion component; receiving the source electromagnetic wave from a first waveguide outside of the slow wave circuit through the first electromagnetic wave channel and transmitting the source electromagnetic wave to the first waveguide conversion component; before conducting and outputting the second electron beam through the second waveguide conversion component and converting the second electromagnetic wave into a third electromagnetic wave of a third transmission mode through the second waveguide conversion component, the method further comprises: receiving the second electron beam from the second waveguide conversion component through the second electron beam channel and transmitting the second electron beam to outside of the slow wave circuit; receiving the third electromagnetic wave from the second waveguide conversion component through the second electromagnetic wave channel and transmitting the third electromagnetic wave to a second waveguide outside of the slow wave circuit.

21. A traveling wave tube, characterized by, The traveling wave tube comprises the slow wave circuit according to any one of claims 1-10, and an electron gun, a magnetic focusing system and a collector coupled with the slow wave circuit; wherein the electron gun is configured to generate and inject a first electron beam into the slow wave circuit, the magnetic focusing system is configured to keep the first electron beam from changing shape during passing through the slow wave circuit, and the collector is configured to receive a second electron beam output by the slow wave circuit.

22. An electromagnetic wave treatment device, characterized by The electromagnetic wave processing device comprises: The traveling wave tube according to claim 21, and a discrete device coupled with the traveling wave tube.

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