A terahertz ribbon injection gyrotron

Abstract

This disclosure provides a terahertz strip beam gyrotron, comprising: a planar cathode for generating a strip beam of electrons; a guiding magnet for generating a magnetic field to cause the strip beam of electrons to propagate along the z-axis under the influence of the magnetic field in the z-axis direction; a confocal waveguide structure for realizing beam-wave interaction on the strip beam of electrons to generate THz electromagnetic radiation; and a collecting electrode for collecting and capturing the strip beam of electrons after beam-wave interaction; wherein the confocal waveguide structure is a laterally open confocal waveguide structure, comprising: two confocal mirror waveguides arranged opposite each other, the focal points of the two confocal mirror waveguides being located on the opposite confocal mirror waveguides.

Description

Technical Field

[0001] The present disclosure relates to the technical field of vacuum terahertz sources, and in particular to a terahertz ribbon injection gyrotron. Background Art

[0002] Terahertz is between millimeter waves and far-infrared light waves. Its unique properties make this band have important application value in the fields of communications, medical imaging, non-destructive testing, imaging radar, etc. Terahertz radiation sources are the basis and key to terahertz technology research. At present, the efficiency of THz radiation sources is low and it is difficult to meet the needs. Therefore, it is necessary to seek effective methods to develop high-power and high-efficiency terahertz radiation sources, which is of great significance to promote the promotion and application of THz waves.

[0003] The traditional cylindrical gyrotron developed based on the electron cyclotron maser mechanism is the main radiation source for generating terahertz waves. It utilizes the interaction between the circular cyclotron electron beam and electromagnetic waves under the relativistic effect to realize the energy exchange between electrons and electromagnetic waves. The high-frequency electromagnetic field absorbs the energy of the electron beam to generate high-power electromagnetic radiation in the terahertz band. Gyrotrons can be widely used in plasma heating, material processing, ceramic sintering, particle acceleration, advanced radar and other aspects.

[0004] Figure 1 The schematic diagram of the structure of the conventional cylindrical gyrotron based on the electron cyclotron maser mechanism in the prior art is mainly composed of a magnetron injection electron gun, an open resonant cavity, an output structure, and a magnet. Figure 1 As shown in the figure, the circular cyclotron electron beam generated by the cathode of the magnetron injection electron gun interacts in the open resonant cavity under the guidance of the magnetic field system to generate electromagnetic waves, which are output through the output window and collected by the collector. The device is characterized in that the operating frequency is related to the magnetic induction intensity and high-frequency structural parameters, and no external excitation signal is required, and it can generate high-power electromagnetic radiation at millimeter waves. However, as Figure 1 As shown in the figure, the traditional cylindrical gyrotron suffers from severe mode competition and greatly reduces the efficiency of injection-wave interaction during its development towards high frequencies. Its output power at 1 THz is in the order of several kW, which is far from meeting the needs of applications. Summary of the invention

[0005] In order to solve the above problems in the prior art, the present disclosure provides a terahertz band injection gyrotron, which is used to solve at least one of the above technical problems.

[0006] The present invention provides a terahertz band-shaped injection gyrotron, comprising: a planar cathode for generating a band-shaped electron beam; a guiding magnet for generating a magnetic field so that the band-shaped electron beam is transmitted along the z-axis direction under the action of the magnetic field in the z-axis direction of the magnetic field; a confocal waveguide structure for realizing an injection-wave interaction on the band-shaped electron beam to generate THz electromagnetic radiation; and a collecting pole for collecting and capturing the band-shaped electron beam after the injection-wave interaction; wherein the confocal waveguide structure is a laterally open confocal waveguide structure, comprising: two confocal mirror waveguides arranged opposite to each other, and the focal points of the two confocal mirror waveguides are located on the confocal mirror waveguides arranged opposite to each other.

[0007] Furthermore, a cutoff section and an output section are provided at both ends of the two confocal mirror waveguides, wherein the cutoff section is used to suppress the reverse propagation of the band electron beam; and the output section is used to output the band electron beam after the beam-wave interaction.

[0008] Furthermore, the two confocal mirror waveguides are both arc segments, and the radius of the arc segment is equal to the distance between the two confocal mirror waveguides.

[0009] Furthermore, the cutoff section and the output section are both tapered waveguides.

[0010] Furthermore, the two confocal mirror waveguides are made of oxygen-free copper material.

[0011] Furthermore, the included angles between the cut-off section and the output section and the confocal mirror waveguide connected thereto are both 1° to 5°.

[0012] Furthermore, the length of the two confocal mirror waveguides is equal to the length of the output section and greater than the length of the cut-off section.

[0013] Furthermore, the distance between the two confocal mirror waveguides is 3 mm to 6 mm.

[0014] Furthermore, the width of the two confocal mirror waveguides is 3 mm to 6 mm.

[0015] Furthermore, the control anode is used for emitting a strip-shaped electron beam from the front of the control anode.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects:

[0017] (1) The present invention adopts an open transverse open confocal waveguide structure and a planar electron beam to construct a new type of gyrotron device, which can not only increase the size of the interactive structure and work in a high-order mode, but also has the advantages of a planar electron beam, reducing the starting current and the operating current, thereby greatly increasing the output efficiency of the terahertz gyrotron.

[0018] (2) Compared with the flat plate structure, the confocal waveguide structure used in the present disclosure can more flexibly control the diffraction loss of different modes by adjusting the width a of the confocal mirror waveguide, and better solve the problem of mode competition. Due to the structural characteristics, the electromagnetic mode TE0n mode of the confocal mirror waveguide is generally selected as the working mode, which has higher interaction efficiency with the strip electron beam and more stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For a more complete understanding of the present disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1 A schematic diagram of the structure of a prior art gyrotron;

[0021] Figure 2 A schematic diagram of the structure of a terahertz band injection gyrotron according to an embodiment of the present disclosure is shown;

[0022] Figure 3 Schematically shows a front view of a cut-off section, a confocal mirror waveguide and an output section according to an embodiment of the present disclosure;

[0023] Figure 4 The figure schematically shows a left side view of a confocal mirror waveguide according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0026] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0027] The present invention provides a terahertz strip injection gyrotron, which is a novel terahertz radiation source based on the electron cyclotron maser mechanism and adopts a strip electron beam and a transverse open confocal waveguide high-frequency structure as the basic structure. Its interaction structure is different from the conventional interaction structure (such as: cylindrical open cavity, coaxial cavity), and the electron beam is also different from the ring electron beam used in the conventional gyrotron.

[0028] Figure 2 The schematic diagram of the structure of a terahertz band injection gyrotron according to an embodiment of the present disclosure is shown schematically.

[0029] like Figure 2 As shown, the terahertz band injection gyrotron has an overall symmetrical structure from top to bottom, including:

[0030] The planar cathode 1 is used to generate a band-shaped electron beam, wherein the band-shaped electron beam is a band-shaped electron beam in the z direction.

[0031] The control anode 2 is used to emit the strip-shaped electron beam from the anode hole in the middle of the control anode 2, and emit it from the front.

[0032] The guiding magnet 4 is arranged at the periphery of the belt-shaped electron beam transmission space, and is used to generate a magnetic field so that the belt-shaped electron beam is transmitted along the z-axis direction under the action of the z-axis magnetic field of the magnetic field.

[0033] The confocal waveguide structure 3 is arranged on the inner side of the guiding magnet 4, and is used to realize the beam-wave interaction for the strip electron beam, and the kinetic energy of the strip electron beam is converted into the energy of the electromagnetic wave to generate THz electromagnetic radiation, wherein the confocal waveguide structure 3 is a laterally open confocal waveguide structure, which is opened in the x-axis direction, and includes: a confocal mirror waveguide 31 and a confocal mirror waveguide 32 arranged opposite to each other, and the focal points of the two confocal mirror waveguides are located on the oppositely arranged confocal mirror waveguides, that is, the focal point of the confocal mirror waveguide 31 is located on the confocal mirror waveguide 32, and the focal point of the confocal mirror waveguide 32 is located on the confocal mirror waveguide 31.

[0034] The collecting electrode 5 is arranged opposite to the control anode 2, and is used for collecting and capturing the band electron beam after the beam-wave interaction.

[0035] The output window 6 is used to output the generated THz electromagnetic radiation, that is, to radiate outwards.

[0036] In the disclosed embodiment, the planar cathode 1 is a planar electron gun cathode, and a small orbit (the electron cyclotron radius is much smaller than the interaction structure radius) magnetron injection electron gun and a large orbit (the electron cyclotron radius is equal to the interaction radius) CUSP (cut-off) electron gun can be used, as long as the corresponding emission conditions are met.

[0037] According to the embodiments of the present disclosure, Figure 3As shown, the confocal mirror waveguide 31 and the confocal mirror waveguide 32 have the same structure and are arranged opposite to each other. They are confocal mirror waveguide structures with uniform thickness. The confocal mirror waveguide 31 (i.e. Figure 3 A cutoff section L1 and an output section L3 are provided at both ends of the confocal mirror waveguide 32, wherein the cutoff section L1 is used to suppress the return propagation of the band electron beam; and the output section L3 is used to output the band electron beam after the beam-wave interaction.

[0038] In the embodiment of the present disclosure, taking a 220GHz terahertz band injection gyrotron as an example, the cutoff section L1 is a slightly downward tapered waveguide, preferably a gradually deformed tapered waveguide, and the inclination angle θ1 between it and the confocal mirror waveguide L2 is 1° to 5°, and the length of the cutoff section L1 is 7mm to 12mm; the output section L3 is a slightly upward tapered waveguide, preferably a gradually deformed tapered waveguide, and the inclination angle θ2 between it and the confocal mirror waveguide L2 is 1° to 5°, the length of the confocal mirror waveguide L2 is equal to that of the output section L3, and is greater than the length of the cutoff section L1, and the length of the confocal mirror waveguide L2 and the output section L3 is preferably 16mm to 22mm. In the embodiment of the present disclosure, the confocal mirror waveguide L2 is a circular arc section of uniform thickness, such as Figure 4 As shown, the radius R of the arc segment c (i.e., radius of curvature) and the distance L between the two confocal mirror waveguides t In the embodiment of the present disclosure, the radius of curvature R c The distance L between the two confocal mirror waveguides t Preferably 3mm to 6mm.

[0039] Among them, the width a of the confocal waveguide structure 3 (i.e., the width of the two confocal mirror waveguides) determines the different diffraction losses of each mode in the strip electron beam. Based on the characteristics of the confocal waveguide structure 3, it has a mode-selective characteristic, which can greatly improve the mode competition. In the embodiment of the present disclosure, the diffraction losses of different modes can be controlled more flexibly by adjusting the width a of the confocal mirror waveguide in the confocal waveguide structure 3, so as to better solve the mode competition problem. Due to the structural characteristics, the electromagnetic mode TE0n mode of the confocal waveguide is generally selected as the working mode, which has a higher interaction efficiency with the strip electron beam and a more stable operation. Among them, the confocal mirror waveguide 31 and the confocal mirror waveguide 32 in the confocal waveguide structure 3 have the same width. Preferably, the confocal mirror waveguide width a of the 220GHz terahertz strip injection gyrotron ranges from 3mm to 6mm, that is, the widths of the confocal mirror waveguide 31 and the confocal mirror waveguide 32 are 3mm to 6mm. Among them, the waveguide widths of the cutoff section L1 and the output section L3 can be equal to or different from the confocal mirror waveguide width, and this disclosure does not limit this.

[0040] In the embodiment of the present disclosure, the confocal mirror waveguide 31 and the confocal mirror waveguide 32 are made of metal materials, such as oxygen-free copper materials, etc. In some other embodiments, the confocal mirror waveguide 31 and the confocal mirror waveguide 32 may also be made of other metal materials.

[0041] The working principle of the terahertz band-injection gyrotron provided by the embodiment of the present disclosure is as follows: a planar electron gun cathode 1 generates a band-shaped electron beam transmitted along the z direction, and the band-shaped electron beam is ejected forward from the anode hole in the middle of the control anode 2, and then a magnetic field along the z-axis direction is generated by a guide magnet 4 arranged on the periphery of the band-shaped electron beam transmission space, and the transmission direction of the band-shaped electron beam is guided so that it is transmitted along the z-axis direction, and based on the electron cyclotron maser mechanism, an injection-wave interaction is realized on the band-shaped electron beam through a confocal waveguide structure 3 with a transverse open structure, so that the kinetic energy of the band-shaped electron beam is converted into the energy of the electromagnetic wave, generating THz electromagnetic radiation, and the band-shaped electron beam after the injection-wave interaction is collected and captured by the collecting pole 5, and finally radiated outward through the output window 6.

[0042] The present invention provides a terahertz band-injection gyrotron, which adopts an open transverse open confocal waveguide structure and a planar electron beam to construct a new type of gyrotron device, which can not only increase the size of the interaction structure and work in a high-order mode, but also has the advantages of a planar electron beam, reducing the starting current and the working current, thereby greatly increasing the output efficiency of the terahertz gyrotron; compared with the flat plate structure, the present invention adopts a confocal waveguide structure to more flexibly control the diffraction loss of different modes by adjusting the confocal mirror waveguide width a, and better solve the problem of mode competition. Due to the structural characteristics, the electromagnetic mode TE0n mode of the confocal mirror waveguide is generally selected as the working mode, which has higher interaction efficiency with the band electron beam and more stable operation.

[0043] It should be noted that the gyrotron structure provided in the above embodiment does not constitute a limitation of the present gyrotron. The shape and size of the gyrotron can be modified according to actual conditions, and the configuration can be more complex. For example, an input structure can be added to the gyrotron to introduce an input signal, which is used to modulate the phase of the band electron beam emitted by the electron gun cathode 1. The electron beam modulated by the input structure is better clustered, and after the beam-wave interaction is carried out through the confocal waveguide structure, most of the energy is transferred to the THz wave, thereby making the output THz power greater.

[0044] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0045] Although the present disclosure has been shown and described with reference to specific exemplary embodiments of the present disclosure, it should be understood by those skilled in the art that various changes in form and details may be made to the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-mentioned embodiments, but should be determined not only by the appended claims, but also by the equivalents of the appended claims.

Claims

1. A terahertz band injection gyrotron, characterized in that: include: A planar cathode (1) for generating a band electron beam; A guide magnet (4) is used to generate a magnetic field so that the band-shaped electron beam is transmitted along the z-axis direction under the action of the magnetic field in the z-axis direction of the magnetic field; A confocal waveguide structure (3) is used to realize beam-wave interaction on the strip electron beam to generate THz electromagnetic radiation; A collecting electrode (5) is used to collect and capture the band electron beam after the beam-wave interaction; The confocal waveguide structure (3) is a laterally open confocal waveguide structure, comprising: two confocal mirror waveguides arranged opposite to each other, the focal points of the two confocal mirror waveguides being located on the confocal mirror waveguides arranged opposite to each other; A cut-off section and an output section are provided at both ends of the two confocal mirror waveguides; wherein the cut-off section is used to suppress the return propagation of the strip electron beam; and the output section is used to output the strip electron beam after the beam-wave interaction; The two confocal mirror waveguides are both arc segments, and the radius of the arc segment is equal to the distance between the two confocal mirror waveguides; The cut-off section and the output section are both tapered waveguides.

2. The terahertz band injection gyrotron according to claim 1, characterized in that: The two confocal mirror waveguides are made of oxygen-free copper material.

3. The terahertz band injection gyrotron according to claim 1, characterized in that: The included angles between the cut-off section and the output section and the confocal mirror waveguide connected thereto are both 1° to 5°.

4. The terahertz band injection gyrotron according to claim 1, characterized in that: The lengths of the two confocal mirror waveguides are equal to the length of the output section and greater than the length of the cut-off section.

5. The terahertz band injection gyrotron according to claim 1, characterized in that: The distance between the two confocal mirror waveguides is 3 mm to 6 mm.

6. The terahertz band injection gyrotron according to claim 1, characterized in that: The width of the two confocal mirror waveguides is 3 mm to 6 mm.

7. The terahertz band injection gyrotron according to claim 1, characterized in that: The gyrotron further comprises: A control anode (2) is used for the strip-shaped electron beam to be emitted from the front of the control anode (2).

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