Electromagnetic wave generator

Abstract

To provide an electromagnetic wave generation device capable of forming a uniform electric field distribution and a pressure distribution inside a waveguide and preventing inhibition of generation and propagation of electromagnetic waves.SOLUTION: An electromagnetic wave generation device (100) includes: a cathode (150) generating an electron beam; an anode (130) positioned opposite to the cathode (150); vacuum cases (110, 110 A) in which the cathode (150) and the anode (130) are provided, and its interior is evacuated to a vacuum; and a waveguide (120) provided inside the vacuum case (110) and composed of a cylindrical conductor electrically connected to the anode (130) and the vacuum case (110) and having a spatial gap symmetrically formed in relation to a central axis of the cylindrical conductor.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an electromagnetic wave generating device capable of propagating electromagnetic waves. [Background technology]

[0002] In recent years, an electron tube called a virtual cathode oscillator (Vircator) has attracted attention as an electromagnetic wave generator that generates high-power electromagnetic waves. In a virtual cathode oscillator, an electron beam exceeding the space-charge-limited current is injected into a waveguide maintained in a vacuum. The injected electrons accumulate inside the waveguide to form a virtual cathode. The formed virtual cathode oscillates electrons in time and space within the waveguide. An electromagnetic wave generator using a virtual cathode oscillator generates high-power electromagnetic waves by oscillating electrons (see, for example, Patent Document 1).

[0003] Furthermore, as a technique for increasing the output of an electromagnetic wave generator, there is a technique for providing one or more reflectors inside the waveguide of the electromagnetic wave generator (see, for example, Patent Document 2, Non-Patent Document 1, and Non-Patent Document 2). In an electromagnetic wave generator with a reflector inside the waveguide, an electron beam emitted from a virtual cathode and transmitted through the reflector further forms a new virtual cathode. By forming multiple virtual cathodes, the electromagnetic wave generator generates electromagnetic waves with a higher output.

[0004] When generating electromagnetic waves in this way, the inside of the waveguide must satisfy certain vacuum and electric field conditions. Ideally, the vacuum conditions should have a spatially uniform pressure distribution. This is because if there are localized areas with low vacuum, high-frequency discharges will occur there, hindering the generation of the plasma state that generates electromagnetic waves. Furthermore, it is desirable for the electric field conditions to have a spatially axially symmetric electric field distribution inside the waveguide, with a local electric field strength of around several MV / m. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-266810 [Patent Document 2] International Publication No. 2006 / 037918 [Patent Document 3] Special Publication No. 2005-505112 [Non-patent literature]

[0006] [Non-Patent Document 1] S. Champeaux et.al, “3-D PIC Numerical Investigation of a Novel Concept of Multistage Axial Vircator for Enhanced Microwave Generation”, IEEE Transactions on Plasma Science 43, 3841(2015) [Non-patent document 2] S. Champeaux et.al, “Improved Design of Multistage Axial Vircator with Reflectors for Enhanced Performances”, IEEE Transactions on Plasma Science 44, 3841(2016) [Non-patent document 3] M.ElfsBerg et al, “Experimental Studies of Anode and Cathode Materials in a Repetitive Driven Axial Vircator”, IEEE Transactions on Plasma Science 36, 688(2008) Summary of the Invention [Problem to be solved by the invention]

[0007] However, in conventional electromagnetic wave generating devices, it is difficult to form uniform electric field distribution and pressure distribution inside the waveguide, and in this case, there is a problem that the generation and propagation of electromagnetic waves are hindered.

[0008] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an electromagnetic wave generating device that can uniformly form electric field distribution and pressure distribution inside a waveguide and prevent the generation and propagation of electromagnetic waves from being obstructed. [Means for solving the problem]

[0009] The electromagnetic wave generating device according to the present disclosure comprises a cathode that generates an electron beam, an anode that is arranged to face the cathode, a vacuum vessel in which the cathode and anode are provided and the interior of which is evacuated to a vacuum, and a cylindrical conductor that is provided inside the vacuum vessel and is electrically connected to the anode and the vacuum vessel, and is spatially symmetrical with respect to the central axis of the cylindrical shape. opening The waveguide has a [Effects of the Invention]

[0010] The electromagnetic wave generating device of the present disclosure uses a waveguide having a spatial gap symmetrical with respect to the central axis of a cylindrical shape, and when the air inside the vacuum container provided outside the waveguide is evacuated, it is possible to form a uniform electric field distribution and pressure distribution inside the waveguide, thereby preventing the generation and propagation of electromagnetic waves from being obstructed. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram of an electromagnetic wave generating system including an electromagnetic wave generating device according to a first embodiment of the present disclosure. [Figure 2] 1 is a cross-sectional view showing the internal configuration of an electromagnetic wave generating device according to a first embodiment of the present disclosure. [Figure 3] FIG. 1 is a schematic configuration diagram of a waveguide according to a first embodiment of the present disclosure. [Figure 4] 1 is a plan view illustrating a configuration of an anode of an electromagnetic wave generating device according to a first embodiment of the present disclosure. [Figure 5]1 is a cross-sectional view illustrating the operating principle of an electromagnetic wave generating device according to a first embodiment of the present disclosure. [Figure 6] FIG. 10 is a cross-sectional view showing the internal configuration of an electromagnetic wave generation device according to a second embodiment of the present disclosure. [Figure 7] FIG. 10 is a cross-sectional view illustrating a configuration of a waveguide according to a second embodiment of the present disclosure. [Figure 8] FIG. 11 is a cross-sectional view showing the internal configuration of an electromagnetic wave generating device according to a third embodiment of the present disclosure. [Figure 9] FIG. 11 is a cross-sectional view illustrating a configuration of a waveguide according to a third embodiment of the present disclosure. [Figure 10] FIG. 10 is a cross-sectional view showing the internal configuration of an electromagnetic wave generating device according to a fourth embodiment of the present disclosure. [Figure 11] FIG. 11 is a cross-sectional view illustrating a configuration of a waveguide according to a fourth embodiment of the present disclosure. [Figure 12] FIG. 11 is a cross-sectional view showing the internal configuration of an electromagnetic wave generating device according to a fifth embodiment of the present disclosure. [Figure 13] 10 is a plan view showing the configuration of a reflector holder and a reflector of an electromagnetic wave generating device according to a fifth embodiment of the present disclosure. FIG. [Figure 14] FIG. 11 is a plan view illustrating a configuration of a reflector of an electromagnetic wave generating device according to a fifth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Embodiment 1 FIG. 1 is a configuration diagram of an electromagnetic wave generating system including an electromagnetic wave generator according to a first embodiment of the present disclosure. As shown in FIG. 1, electromagnetic wave generator 100 is connected to high-voltage pulse generator 200 and vacuum pump 300. When generating electromagnetic waves in this electromagnetic wave generating system, first, the inside of electromagnetic wave generator 100 is evacuated by vacuum pump 300 to a predetermined vacuum level. When a high-voltage pulse is input from high-voltage pulse generator 200 while the internal vacuum level is maintained, electrons are accelerated inside electromagnetic wave generator 100, and a virtual cathode formed by the electrons clustering in the waveguide is generated, thereby generating electromagnetic waves 400. Note that while FIG. 1 shows an example configured only with electromagnetic wave generator 100 and high-voltage pulse generator 200, it is also possible to use only electromagnetic wave generator 100 and high-voltage pulse generator 200 without using vacuum pump 300. In such a case, when manufacturing the electromagnetic wave generator 100, the inside is evacuated to a predetermined vacuum level, and then the electromagnetic wave generator 100 is sealed to maintain the internal vacuum level.

[0013] FIG. 2 is a cross-sectional view showing the internal configuration of the electromagnetic wave generator according to the first embodiment of the present disclosure. As shown in FIG. 2, the electromagnetic wave generator 100 includes a first vacuum vessel 110 and a second vacuum vessel 110A, which are arranged side by side and maintain a predetermined vacuum level inside the first vacuum vessel 110A. A cathode 150 that generates an electron beam is provided inside the second vacuum vessel 110A. An anode 130 is provided between the first vacuum vessel 110 and the second vacuum vessel 110A so as to face the cathode 150. While FIG. 2 shows an example in which the electromagnetic wave generator 100 is divided into the first vacuum vessel 110 and the second vacuum vessel 110A, the first vacuum vessel 110 and the second vacuum vessel 110A may be integrated into a single vacuum vessel in which the anode 130 and the cathode 150 are provided. By adjusting the distance d [mm] between the anode 130 and the cathode 150, the current amount of the generated electron beam and the frequency of the electromagnetic wave are determined.

[0014] The first vacuum vessel 110 is, for example, a hollow cylinder with both ends open. Hereinafter, the central axis of the first vacuum vessel 110 is referred to as the Zz axis. A transmission window 111 that transmits electromagnetic waves is provided at the end of the first vacuum vessel 110 in the z-axis direction, intersecting the Zz axis. An anode 130 is provided at the end of the first vacuum vessel 110 opposite the transmission window 111, intersecting the Zz axis. A cylindrical waveguide 120 is provided inside the first vacuum vessel 110. The waveguide 120 is open at both ends and extends from the position where the anode 130 is provided toward the position where the transmission window 111 is provided. Hereinafter, the end of the waveguide 120 facing the anode 130 will be referred to as one end, and the end facing the transmission window 111 will be referred to as the other end. The vacuum pump 300 evacuates the inside of the first vacuum vessel 110 and the inside of the second vacuum vessel 110A.

[0015] 3 is a schematic diagram of a waveguide of the electromagnetic wave generating device according to the first embodiment of the present disclosure. The waveguide 120 is made of a cylindrical conductor and has a spatial gap symmetrical with respect to the central axis. The cylindrical shape is not limited to a shape with a side surface formed along the circumferential direction, but also includes a shape with multiple conductors arranged along the circumferential direction. The waveguide 120 is electrically connected from one end to the other by conductors, and the first vacuum container 110, the second vacuum container 110A, and the anode 130 are maintained at the same potential.

[0016] The waveguide 120 is disposed, for example, such that its central axis coincides with the central axis Zz-axis of the first vacuum vessel 110. The cathode 150 is disposed, for example, on an extension of the Zz-axis. Inside the waveguide 120, an electron beam is incident from one end, and an electromagnetic wave 400 is output from the other end.

[0017] As shown in Fig. 3, the waveguide 120 in this embodiment is formed as a hollow cylinder having a side surface along the circumferential direction, and a plurality of through holes 140 are formed in the side surface as spatial gaps. Here, Fig. 3 shows an example in which the through holes 140 are round holes, but they may be formed symmetrically with respect to the central axis of the cylindrical shape, and may be, for example, slit-shaped.

[0018] In the electromagnetic wave generating device 100, in order to generate electromagnetic waves, the inside of the waveguide 120 needs to be evacuated to a predetermined vacuum condition. Since the waveguide 120 has a cylindrical shape with a spatial gap symmetrical with respect to the central axis, when the first vacuum container 110 and the second vacuum container 110A are evacuated by the vacuum pump 300, the degree of vacuum inside the waveguide 120 can be maintained uniformly.

[0019] 4 is a plan view showing the configuration of the anode of the electromagnetic wave generating device according to embodiment 1 of the present disclosure. As shown in Fig. 4, anode 130 includes anode body 131 made of a metal mesh that is easily permeable to electrons or a metal thin film having a thickness of about μm, and anode frame 132 that holds anode body 131.

[0020] FIG. 5 is a cross-sectional view illustrating the operating principle of the electromagnetic wave generator according to the first embodiment of the present disclosure. The following describes the operation of the electromagnetic wave generator 100, which generates an electron beam from the cathode 150 and generates electromagnetic waves. Here, it is assumed that the insides of the first vacuum vessel 110 and the second vacuum vessel 110A are maintained at a vacuum of, for example, about 0.1 mPa. In this state, when a high voltage (several hundred kV or more) in a pulsed form (with a pulse width of about 10 ns to 100 ns) is applied between the anode 130 and the cathode 150 by the high-voltage pulse generator 200, an electron beam is generated from the cathode 150 toward the anode 130. The electron beam passes through the anode 130 and enters the waveguide 120. At this time, the current of the electron beam is a space-charge-limited current I expressed by the following equation (1): c When the wavelength exceeds 1000 Å, a virtual cathode 420 is formed inside the waveguide 120.

[0021]

number

[0022]

number

[0023] The virtual cathode 420 is a region where electrons are spatially concentrated. Therefore, electrons passing through the anode 130 toward the virtual cathode 420 are decelerated and reflected by the potential of the virtual cathode 420, as shown in electron beam 410. This phenomenon causes the electrons to oscillate between the cathode 150 and the virtual cathode 420, generating electromagnetic waves 400.

[0024] The relationship between the distance d [mm] between the anode 130 and the cathode 150 and the frequency f [Hz] of the electromagnetic wave 400 is expressed by the following formula (3).

[0025]

number

[0026]

number

[0027] The frequency of the electromagnetic wave 400 generated by the electromagnetic wave generator 100 is expressed by Equation (3). Therefore, to change the frequency of the electromagnetic wave 400, it is necessary to adjust the distance d between the anode 130 and the cathode 150 or the voltage V of the electrons passing through the waveguide 120. For example, when the distance d is fixed at 10 mm, the voltage V must be adjusted to 80 kV to generate an electromagnetic wave with a frequency of 3 GHz, and to 200 kV to generate an electromagnetic wave 400 with a frequency of 4 GHz. Furthermore, when the voltage V is fixed at 200 kV, the distance d must be adjusted to 13 mm to generate an electromagnetic wave with a frequency of 3 GHz, and to 10 mm to generate an electromagnetic wave with a frequency of 4 GHz. In order for the electromagnetic wave 400 to pass through the waveguide 120, it is necessary to satisfy the cutoff frequency of the waveguide 120. One example of the electromagnetic wave assumed in this disclosure is the TM mode. In order to oscillate electromagnetic waves in a single mode inside the waveguide 120, the fundamental mode, TM 01 Therefore, the frequency f of the oscillating electromagnetic wave must be selected according to the condition of equation (5).

[0028]

number

[0029]

number

[0030]

number

[0031] In the electromagnetic wave generating device 100, the length L of the waveguide 120 is adjusted to 01It attenuates electromagnetic waves other than the specified mode. To ensure sufficient attenuation, a length of about 10 times the wavelength is required. The relationship between wavelength λ and frequency f is c=fλ, so as mentioned above, for an electromagnetic wave of 2 GHz, wavelength λ is 15 cm. In this case, the length L of the waveguide 120 needs to be about 1.5 m.

[0032] As described above, the electromagnetic wave generating device 100 according to the first embodiment includes the cathode 150 that generates an electron beam, the anode 130 that is arranged opposite the cathode 150, the vacuum vessels 110, 110A in which the cathode 150 and the anode 130 are provided and which are evacuated to a vacuum, and the waveguide 120 that is provided inside the vacuum vessel 110 and is made of a cylindrical conductor electrically connected to the anode 130 and the vacuum vessel 110, and has a spatial gap formed symmetrically with respect to the central axis of the cylindrical shape.

[0033] In this way, the waveguide 120 is provided with spatial gaps formed symmetrically with respect to the central axis of the cylindrical shape, and an axially symmetric electric field is formed inside the waveguide 120 under the condition that the degree of vacuum around the virtual cathode 420 is uniform. This makes it possible to prevent the generation and propagation of electromagnetic waves from being hindered.

[0034] Embodiment 2 6 is a cross-sectional view showing the configuration of an electromagnetic wave generator according to a second embodiment of the present disclosure. In the first embodiment, the waveguide 120 of the electromagnetic wave generator 100 is formed as a hollow cylinder having a side surface along the circumferential direction, and a plurality of through-holes 140 are formed on the side surface symmetrically with respect to the axis as spatial gaps. In contrast, the waveguide 120A of the electromagnetic wave generator 100A according to the second embodiment is formed by a plurality of metal rods 121 arranged in a ring shape at equal intervals. The following description will focus on the differences from the first embodiment, and similarities will be omitted as appropriate.

[0035] As shown in Fig. 6, the electromagnetic wave generator 100A has a first vacuum vessel 110 and a second vacuum vessel 110A arranged side by side. An anode 130 is provided between the first vacuum vessel 110 and the second vacuum vessel 110A so as to face the cathode 150. The cathode 150 that generates an electron beam is also provided inside the second vacuum vessel 110A. A transmission window 111 that transmits electromagnetic waves is provided at one end of the first vacuum vessel 110 so as to intersect with the central axis Zz-axis of the first vacuum vessel 110. The anode 130 is provided at the end of the first vacuum vessel 110 opposite the transmission window 111 so as to intersect with the Zz-axis. The waveguide 120A is provided inside the first vacuum vessel 110, and the plurality of metal rods 121 that form the waveguide 120A are each provided inside the first vacuum vessel 110, extending from one end on the anode 130 side to the other end on the transmission window 111 side. The waveguide 120A is electrically connected by a conductor from one end on the anode 130 side to the other end on the transmission window 111 side, and the first vacuum vessel 110, the second vacuum vessel 110A, and the anode 130 are maintained at the same potential.

[0036] FIG. 7 is a cross-sectional view showing the configuration of a waveguide according to the second embodiment of the present disclosure. As shown in FIG. 7, a plurality of metal rods 121 are arranged at equal intervals in the circumferential direction with respect to the direction of the central axis Zz of the first vacuum vessel 110. When the inside of the first vacuum vessel 110 is evacuated using a vacuum pump 300, an axially symmetric electric field is formed inside the waveguide 120A formed by the metal rods 121 under conditions of a uniform degree of vacuum. Here, FIG. 7 shows an example in which 16 metal rods 121 are provided, but the number does not have to be 16 as long as the structure is spatially symmetric.

[0037] As described above, the waveguide 120A of the electromagnetic wave generating device 100A according to this embodiment is formed by arranging a plurality of metal rods 121 at equal intervals in a ring shape. In this embodiment, as in the first embodiment, the electric field distribution and pressure distribution inside the waveguide 120A can be made uniform, thereby preventing the generation and propagation of electromagnetic waves from being hindered.

[0038] Embodiment 3 FIG. 8 is a cross-sectional view showing the configuration of an electromagnetic wave generator according to a third embodiment of the present disclosure. FIG. 9 is a cross-sectional view showing the configuration of a waveguide according to the third embodiment of the present disclosure. Waveguide 120B of electromagnetic wave generator 100B of this embodiment is wire mesh 122 rolled into a cylindrical shape. Wire mesh 122 is, for example, woven from metal wires to have a mesh size of 10 mm or less. The following description will focus on differences from the first embodiment, and similarities will be omitted as appropriate.

[0039] As shown in FIG. 8, the electromagnetic wave generator 100B includes a first vacuum vessel 110 and a second vacuum vessel 110A arranged side by side. An anode 130 is provided between the first vacuum vessel 110 and the second vacuum vessel 110A, facing the cathode 150. The cathode 150 for generating an electron beam is also provided inside the second vacuum vessel 110A. A transmission window 111 that transmits electromagnetic waves is provided at one end of the first vacuum vessel 110, intersecting the central axis Zz-axis of the first vacuum vessel 110. An anode 130 is provided at the end of the first vacuum vessel 110 opposite the transmission window 111, intersecting the Zz-axis. The waveguide 120B is provided inside the first vacuum vessel 110, extending from one end on the anode 130 side to the other end on the transmission window 111 side. The waveguide 120B is electrically connected by a conductor from one end on the anode 130 side to the other end on the transmission window 111 side, and the first vacuum container 110, the second vacuum container 110A and the anode 130 are kept at the same potential.

[0040] The waveguide 120B is disposed, for example, such that its central axis coincides with the central axis Zz-axis of the first vacuum vessel 110. The cathode 150 is disposed, for example, on an extension of the Zz-axis. An electron beam enters the waveguide 120B from one end, and an electromagnetic wave 400 is output from the other end.

[0041] As described above, the waveguide 120B of the electromagnetic wave generator 100B according to this embodiment is formed by rolling the wire mesh 122 into a cylindrical shape. In this embodiment, as in the first embodiment, the electric field distribution and pressure distribution in the waveguide 120B can be made uniform, thereby preventing the generation and propagation of electromagnetic waves from being hindered.

[0042] Embodiment 4 10 is a cross-sectional view showing the configuration of an electromagnetic wave generator according to embodiment 4 of the present disclosure. A waveguide 120C of an electromagnetic wave generator 100C of this embodiment is formed using a metal wire 123. The following description will focus on differences from embodiment 1, and similarities will be omitted as appropriate.

[0043] FIG. 11 is a cross-sectional view showing the configuration of a waveguide according to the fourth embodiment of the present disclosure. As shown in FIG. 11, an electromagnetic wave generator 100C includes a first vacuum vessel 110 and a second vacuum vessel 110A arranged side by side. An anode 130 is provided between the first vacuum vessel 110 and the second vacuum vessel 110A so as to face the cathode 150. The cathode 150 that generates an electron beam is also provided inside the second vacuum vessel 110A. A transmission window 111 that transmits electromagnetic waves is provided at one end of the first vacuum vessel 110 and intersects with the central axis Zz-axis of the first vacuum vessel 110. An anode 130 is provided at the end of the first vacuum vessel 110 opposite the transmission window 111 so as to intersect with the Zz-axis.

[0044] The waveguide 120C is provided inside the first vacuum vessel 110. The waveguide 120C is formed into a cylindrical shape by extending a metal wire 123 from a position where the anode 130 is provided to a position where the transmission window 111 is provided, and moving the metal wires 123 back and forth multiple times while shifting them along the circumferential direction so that the metal wires 123 do not overlap each other. The waveguide 120C is electrically connected by a conductor from one end on the anode 130 side to the other end on the transmission window 111 side, and the first vacuum vessel 110, the second vacuum vessel 110A, and the anode 130 are maintained at the same potential.

[0045] The waveguide 120C is disposed, for example, such that its central axis coincides with the central axis Zz-axis of the first vacuum vessel 110. The cathode 150 is disposed, for example, on an extension of the Zz-axis. An electron beam enters the waveguide 120C from one end, and an electromagnetic wave 400 is output from the other end.

[0046] As described above, the waveguide 120C of the electromagnetic wave generator 100C according to this embodiment is formed by passing the metal wire 123 back and forth between the anode 130 and the transmission window 111. In this embodiment, as in the first embodiment, the electric field distribution and pressure distribution inside the waveguide 120C can be made uniform, thereby preventing the generation and propagation of electromagnetic waves from being hindered.

[0047] Embodiment 5. FIG. 12 is a cross-sectional view showing the configuration of a reflector of an electromagnetic wave generator according to a fifth embodiment of the present disclosure. Electromagnetic wave generator 100D includes first reflector 180 and second reflector 180A for reflecting electromagnetic waves inside first vacuum vessel 110. First reflector 180 and second reflector 180A are made of a metal mesh or a metal thin film with a thickness of about μm, which allows electrons to easily pass through. Hereinafter, as an example, electromagnetic wave generator 100D will be described as including waveguide 120A in which multiple metal rods 121 are arranged in a ring shape at equal intervals. The following description will focus on differences from the first embodiment, and similarities will be omitted as appropriate.

[0048] 12, a first reflector 180 and a second reflector 180A are provided inside the first vacuum vessel 110 with a gap therebetween so as to face the anode 130. The first reflector 180 is supported by a first reflector holder 181, and the second reflector 180A is supported by a second reflector holder 181A. The first reflector holder 181 and the second reflector holder 181A are provided so that a plurality of metal rods 121 pass through each of them. The first reflector holder 181 and the second reflector holder 181A are arranged so as to be spatially symmetrical inside the first vacuum vessel 110.

[0049] FIG. 13 is a plan view illustrating the configuration of a reflector holder and a reflector of an electromagnetic wave generating device according to a fifth embodiment of the present disclosure. FIG. 14 is a plan view illustrating the configuration of a reflector holder and a reflector of an electromagnetic wave generating device according to the fifth embodiment of the present disclosure. As illustrated in FIGS. 13 and 14 , first reflector holder 181 and second reflector holder 181A each have an annular surface, and first metal connection portion 182 and second metal connection portion 182A extend from the inner periphery of the annular surface toward the center, respectively. First reflector 180 and second reflector 180A are fixed to the center of first reflector holder 181 and second reflector holder 181A by first metal connection portion 182 and second metal connection portion 182A. Here, first metal connection portion 182 and second metal connection portion 182A have a thickness that does not hinder electron transmission so as to form virtual cathode 420.

[0050] When using waveguide 120A formed of multiple metal rods 121, multiple through holes are formed in the annular surfaces of first reflector holder 181 and second reflector holder 181A to allow multiple metal rods 121 to pass through. This allows waveguide 120A formed of multiple metal rods 121 to be positioned without interfering with its function. At this time, first reflector 180 and first reflector holder 181, and second reflector 180A and second reflector holder 181A have the same potential.

[0051] The electrons generated from the cathode 150 are accelerated or transmitted between the anode 130 and the first and second reflectors 180 and 180A spaced apart from the anode, forming multiple virtual cathodes that generate electromagnetic waves.

[0052] As described above, in electromagnetic wave generator 100D according to this embodiment, first reflector 180 and second reflector 180A are provided at an interval inside waveguide 120A so as to face anode 130. In this embodiment, as in embodiment 1, the electric field distribution and pressure distribution inside waveguide 120A can be made uniform, thereby preventing the generation and propagation of electromagnetic waves from being hindered. Furthermore, in this embodiment, by providing first reflector 180 and second reflector 180A, electrons can be effectively utilized, thereby increasing the output efficiency of electromagnetic waves.

[0053] In the present embodiment, as an example, the electromagnetic wave generator 100D includes the first reflector 180 and the second reflector 180A. However, the number of reflectors is not limited to this, and the electromagnetic wave generator 100D may include a single reflector or multiple reflectors. However, there are optimal values ​​for the number and diameter of the reflectors installed inside the waveguide 120 that maximize the output for each condition under which the electromagnetic waves are generated. Therefore, it is preferable to determine the number and diameter of the reflectors taking into consideration the output value and manufacturability required for the electromagnetic wave generator 100D.

[0054] Furthermore, in this embodiment, an example in which 16 metal rods 121 are provided is shown, but the number does not have to be 16 as long as the structure is spatially symmetrical.

[0055] Also, an example is shown in which four first metal connection parts 182 and four second metal connection parts 182A are provided, but this is not limited to this, and it is sufficient that the number of first reflector holder 181 and second reflector holder 181A can support first reflector 180 and second reflector 180A, respectively.

[0056] Furthermore, in this embodiment, as an example, the electromagnetic wave generating device 100D is provided with the waveguide 120A in which a plurality of metal rods 121 are arranged in a ring shape at equal intervals, but the waveguides 120, 120B, and 120C may be configured to include a plurality of reflectors.

[0057] In the present embodiment, an example has been shown in which the electromagnetic wave generator 100E includes the first reflector 180 and the second reflector 180A, but the number of reflectors is not limited to this, and the device may include one reflector or multiple reflectors. However, there are optimal values ​​for the number and diameter of the reflectors installed inside the waveguide 120 that maximize the output for each condition under which the electromagnetic waves are generated. Therefore, it is preferable to determine the number and diameter of the reflectors taking into consideration the output value and manufacturability required for the electromagnetic wave generator 100E.

[0058] The configurations described in the above embodiments are merely examples of the contents of the present disclosure, and may be combined with other known technologies. Furthermore, parts of the configurations may be omitted or modified without departing from the gist of the present disclosure.

[0059] Various aspects of the present disclosure are summarized below as appendices.

[0060] (Appendix 1) a cathode for generating an electron beam; an anode disposed opposite the cathode; a vacuum vessel in which the cathode and the anode are provided and the inside of which is evacuated to a vacuum; a waveguide provided inside the vacuum vessel, the waveguide comprising a cylindrical conductor electrically connected to the anode and the vacuum vessel, the waveguide having a spatial gap formed symmetrically with respect to a central axis of the cylindrical shape; An electromagnetic wave generating device comprising: (Appendix 2) 2. The electromagnetic wave generating device according to claim 1, wherein a transmission window that transmits electromagnetic waves is provided at one end of the vacuum vessel, and the waveguide extends from a position where the anode is provided toward a position where the transmission window is provided. (Appendix 3) The electromagnetic wave generating device according to claim 1 or 2, wherein the waveguide is a hollow cylinder having a side surface along a circumferential direction, and a plurality of through holes are formed in the side surface as the spatial gap. (Appendix 4) 3. The electromagnetic wave generating device according to claim 1, wherein the waveguide is a plurality of metal rods arranged in a ring shape at intervals. (Appendix 5) 3. The electromagnetic wave generating device according to claim 1, wherein the waveguide is a wire mesh rolled into the cylindrical shape. (Appendix 6) 6. The electromagnetic wave generating device according to claim 5, wherein the wire mesh has a mesh size of 10 mm or less. (Appendix 7) 3. The electromagnetic wave generating device according to claim 1, wherein the waveguide is a metal wire that travels back and forth multiple times from a position where the anode is provided to a position where the transmission window is provided. (Appendix 8) 8. The electromagnetic wave generator according to claim 1, wherein a reflector is provided inside the waveguide so as to face the anode. [Explanation of symbols]

[0061] 100 electromagnetic wave generator, 110 first vacuum vessel, 110A second vacuum vessel, 111 transmission window, 120 waveguide, 121 metal rod, 122 wire mesh, 123 metal wire, 130 anode, 131 anode body, 132 anode frame, 140 through hole, 150 cathode, 180 first reflector, 180A second reflector, 181 first reflector holder, 181A second reflector holder, 182 first metal connection part, 182A second metal connection part, 200 high voltage pulse generator, 300 vacuum pump, 400 electromagnetic wave, 410 electron beam, 420 virtual cathode

Claims

1. a cathode for generating an electron beam; an anode disposed opposite the cathode; a vacuum vessel in which the cathode and the anode are provided and the inside of which is evacuated to a vacuum; a waveguide provided inside the vacuum vessel, the waveguide being made of a cylindrical conductor electrically connected to the anode and the vacuum vessel, the waveguide having spatial openings formed symmetrically with respect to a central axis of the cylindrical shape; An electromagnetic wave generating device comprising:

2. 2. The electromagnetic wave generating device according to claim 1, wherein a transmission window that transmits electromagnetic waves is provided at one end of the vacuum vessel, and the waveguide extends from a position where the anode is provided toward a position where the transmission window is provided.

3. 3. The electromagnetic wave generating device according to claim 1, wherein the waveguide is a hollow cylinder having a side surface along a circumferential direction, and a plurality of through holes are formed in the side surface as the spatial opening.

4. A cathode that generates an electron beam; an anode disposed opposite the cathode; a vacuum vessel in which the cathode and the anode are provided and the inside of which is evacuated to a vacuum; a waveguide provided inside the vacuum vessel and consisting of a cylindrical conductor electrically connected to the anode and the vacuum vessel, in which a plurality of metal rods are arranged in an annular shape symmetrically with respect to a central axis of the cylindrical shape at intervals, and gaps are formed between the plurality of metal rods; An electromagnetic wave generating device comprising:

5. 3. The electromagnetic wave generating device according to claim 1, wherein the waveguide is a wire mesh rolled into the cylindrical shape, and the opening is a mesh of the wire mesh.

6. 6. The electromagnetic wave generator according to claim 5, wherein the wire mesh has a mesh size of 10 mm or less.

7. A cathode that generates an electron beam; an anode disposed opposite the cathode; a vacuum vessel in which the cathode and the anode are provided and the inside of which is evacuated to a vacuum; a waveguide made of a cylindrical conductor provided inside the vacuum vessel and electrically connected to the anode and the vacuum vessel; a transmission window that transmits electromagnetic waves is provided at one end of the vacuum vessel; The waveguide is an electromagnetic wave generating device in which a metal wire travels back and forth multiple times symmetrically about the central axis of the cylindrical shape from the position where the anode is provided to the position where the transmission window is provided, and gaps are formed between the metal wires.

8. 3. The electromagnetic wave generating device according to claim 1, wherein a reflector is provided inside the waveguide so as to face the anode.

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