Electromagnetic radiation generation
Through the combination of Cherenkov-type interaction and high-efficiency electron beam collector, the problem of insufficient electromagnetic radiation generation efficiency and output power in the prior art is solved, and efficient and stable electromagnetic radiation generation is achieved, supporting the high-power application of fusion reaction systems.
Patent Information
- Application Number
- CN202380090062.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-11-10
- Filing Date
- 2023-11-08
- Publication Date
- 2025-08-08
AI Technical Summary
The prior art is difficult to effectively generate electromagnetic radiation in high-power applications, especially in plasma heating and other high-power applications in fusion reaction systems. The efficiency and output power of existing equipment such as cyclotrons and BWO/TWTs are insufficient to meet the demand.
A device is adopted that includes an electron source, a magnetic field generator, a cylindrical waveguide and an electron beam collector. It generates electromagnetic radiation through Cherenkov-type interactions, uses a cylindrical waveguide to promote the interaction between the electron beam and the electromagnetic field, and recovers energy through an efficient electron beam collector to improve energy efficiency.
It realizes efficient generation of electromagnetic radiation in the range of 10GHz to 10THz, with an efficiency of more than 80%, and an output power in the range of 0.5MW to 2MW, supporting the stable operation of the fusion reaction system and the reduction of energy input.
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Figure CN120457776A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the generation of electromagnetic radiation for use, particularly but not exclusively, in high power applications such as plasma heating in fusion reactor systems, remote environmental monitoring, and quality assessment of large area composite materials. Background Art
[0002] Gyrotrons provide a continuous wave (CW) electromagnetic (EM) radiation source for high-power applications, such as plasma heating in fusion reactor systems. These gyrotrons can deliver output powers of 0.5 MW to 2 MW in the frequency range of 70 GHz to 300 GHz (where higher power is associated with lower frequencies). Experiments have shown that gyrotrons can achieve efficiencies of up to 50% at lower frequencies. Other EM radiation sources, such as backward wave oscillators (BWOs) and traveling wave tubes (TWTs), can exceed 70% efficiency. However, the output power of a BWO or TWT may not exceed 1 kW, which is insufficient for high-power applications.
[0003] In order to achieve higher efficiency, a multi-stage depressed collector (MDC) can be used to recover energy from the system. Due to the need to extract energy from the circular motion of the spiral electron beam (i.e., the spiral trajectory of the electron beam), the efficiency of the gyrotron cannot exceed 55%. The circular motion of the spiral electron beam is used to support the interaction between the electron beam and the EM wave of the transverse electric (TE) mode in the gyrotron cavity. In order to achieve high efficiency (about 30%-40%) in microwave generation, more than 50% of the energy in the electron beam in the high-power gyrotron is in a circular motion state, which limits the ability of the energy recovery stage to further increase the efficiency to more than 55%. BWO / TWT is driven by a laminar electron beam, 90% of the energy in the electron beam is in a translational motion state, which enables it to both generate microwave radiation and efficiently recover energy from the remaining electron beam through MDC (efficiency can reach 80%). BWO / TWT cannot achieve megawatt-level powers (as required for fusion) because the lateral dimensions (e.g., diameter) of the interaction region must be comparable to the interaction wavelength to suppress the excitation of parasitic modes, thus limiting the power that can be generated. Increasing the diameter of the interaction region is expected to result in the source being unable to maintain stable, steady-state, single-mode operation. Summary of the Invention
[0004] As described above, existing technologies for generating electromagnetic radiation for high-power applications such as plasma heating in fusion reactor systems and other high-power applications have limitations. Therefore, improvements aimed at addressing these limitations would be valuable.
[0005] Therefore, according to a first aspect of the present disclosure, there is provided a device configured to generate electromagnetic radiation, the electromagnetic radiation including frequency components in the frequency range of 10 GHz to 10 THz. The device includes an electron source configured to generate an electron beam. The device also includes a magnetic field generator configured to generate a magnetic field to adjust and guide the electron beam within an interaction region where the electromagnetic radiation is generated. The device also includes a waveguide comprising a cylindrical structure. The cylindrical structure is coaxially aligned with the electron beam in the interaction region. The inner surface of the cylindrical structure is configured to promote a Cherenkov-type interaction between the electron beam and the electromagnetic field excited and maintained inside the waveguide to generate electromagnetic radiation. The device also includes an output coupler configured to output electromagnetic radiation from the device. The device also includes an electron beam collector configured to collect the electron beam after the interaction region and recover energy from the electron beam.
[0006] According to a second aspect of the present disclosure, a method for generating electromagnetic radiation is provided, the electromagnetic radiation including frequency components within a frequency range of 10 GHz to 10 THz. The method includes generating an electron beam. The method also includes generating a magnetic field to condition and guide the electron beam within an interaction region where the electromagnetic radiation is generated. The method also includes using a waveguide comprising a cylindrical structure to promote a Cherenkov-type interaction between the electron beam and an electromagnetic field excited and maintained within the waveguide, thereby generating the electromagnetic radiation. The cylindrical structure is coaxially aligned with the electron beam in the interaction region. The method also includes outputting the electromagnetic radiation. The method also includes collecting the electron beam after the interaction region to recover energy from the electron beam.
[0007] According to a third aspect of the present disclosure, a fusion reaction system is provided. The fusion reaction system includes a chamber configured to confine plasma. The fusion reaction system also includes an apparatus according to the first aspect or any related embodiment. The electromagnetic radiation output by the apparatus is configured to heat the plasma.
[0008] According to a fourth aspect of the present disclosure, a waveguide for a device configured to generate electromagnetic radiation including frequency components within a frequency range of 10 GHz to 10 THz is provided. The waveguide comprises a cylindrical structure. The inner surface of the cylindrical structure is configured to promote a Cherenkov-type interaction between an electron beam generated by the device and an electromagnetic field excited and maintained within the waveguide to generate electromagnetic radiation. The cylindrical structure is coaxially aligned with the electron beam in a magnetic field interaction region for conditioning and guiding the electron beam, where electromagnetic radiation is generated. The diameter D of the cylindrical structure satisfies the condition D / λ>3, where λ is the wavelength associated with the frequency component.
[0009] According to the various aspects described above and the various embodiments described below, limitations of the prior art are addressed. Specifically, coherent, high-power (e.g., in the range of, but not limited to, 0.5 MW to 2 MW) EM radiation can be generated with greater efficiency (e.g., approximately 80% but not limited thereto) than gyrotron technology. Thus, an improved apparatus and method for generating electromagnetic radiation, an improved waveguide for facilitating electromagnetic radiation generation using such an apparatus, and an improved fusion reaction system are provided.
[0010] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Exemplary embodiments of the present invention will now be described, by way of example only, with reference to the following drawings, in which:
[0012] Figure 1 is a schematic diagram of an apparatus configured to generate electromagnetic radiation according to one embodiment;
[0013] Figure 2 is a schematic diagram of a waveguide used in an apparatus according to one embodiment;
[0014] Figure 3 is a schematic diagram of a fusion reaction system according to one embodiment; and
[0015] Figure 4 Refers to a method for generating electromagnetic radiation according to one embodiment. DETAILED DESCRIPTION
[0016] As mentioned above, although certain technologies such as BWO / TWT exist for efficient electromagnetic radiation generation (e.g., in the frequency range between 70 GHz and 300 GHz), such technologies cannot generate EM radiation with output power suitable for high-power applications (e.g., plasma heating in fusion reactor systems), nor can they operate at higher frequencies (e.g., above 300 GHz) to generate sufficient output power (e.g., above 10 W). Therefore, other technologies such as gyrotrons have been used for such high-power applications.
[0017] For nuclear fusion to be commercially viable, the power output of a fusion reactor must exceed the system's energy input. This energy input involves heating the plasma to a high enough temperature to trigger the fusion reaction. Any improvement in energy efficiency, no matter how small, in any part of the fusion reactor system could potentially help create a commercially viable fusion reactor. Gyrotrons have efficiencies as high as 55%, but are relatively inefficient at generating electromagnetic radiation compared to other technologies.
[0018] Therefore, improvements are needed.
[0019] Figure 1 is a schematic diagram of an apparatus 100 configured to generate electromagnetic (EM) radiation 102 according to one embodiment. The generated EM radiation 102 includes frequency components within a frequency range of 10 GHz to 10 THz.
[0020] The apparatus 100 includes an electron source 104 (e.g., an electron gun) configured to generate an electron beam 106. As explained in more detail herein, the electron source 104 is configured to generate the electron beam 106 in a form suitable for conditioning and directing within the apparatus 100. Figure 1 Although not specifically shown, the electron source 104 may include a set of components for facilitating the generation of the electron beam 106. For example, the electron source 104 may include an electron gun for generating the electron beam 106.
[0021] The apparatus 100 also includes a magnetic field generator 108 configured to generate a magnetic field to condition and guide the electron beam 106 within the interaction region where the EM radiation 102 is generated. One or more magnetic field generators 108 (e.g., coils) may be included as part of the apparatus 100 to provide the conditioning and guiding functions. It may be desirable to condition the electron beam 106 by compressing, shaping, and / or "cooling" (meaning changing the beam shape in 6-dimensional (velocity, spatial) parameter space, as described in more detail below) using the magnetic field generator 108. Such conditioning may prepare the electron beam for better interaction with the electromagnetic field within the apparatus 100. As used herein, the term "guiding" refers to driving the electron beam 106.
[0022] Magnetic field generator 108 may include a cryogenically cooled electromagnetic system or a cryogen-free magnet system, such as may be implemented in a gyrotron. The function of generating the magnetic field by magnetic field generator 108 may differ from the function of generating the magnetic field in a gyrotron. For example, in a gyrotron, the magnetic field serves to drive the spiral electron beam and tune it to the operating mode and frequency of the gyrotron. In apparatus 100, the magnetic field is used to drive electron beam 106 and facilitate interaction between electron beam 106 and other components of apparatus 100, as described in more detail below.
[0023] As used herein, the term "interaction region" refers to a portion of the device 100 where electromagnetic radiation 102 is generated as a result of an interaction as described in more detail below.
[0024] The apparatus 100 further includes a waveguide 110. The waveguide 110 comprises a cylindrical structure. The cylindrical structure is coaxially aligned with the electron beam 106 in the interaction region. The inner surface of the cylindrical structure is configured to promote a Cerenkov-type interaction between the electron beam 106 and the electromagnetic field excited and maintained within the waveguide 110 to produce the electromagnetic radiation 102.
[0025] The physics behind the generation of electromagnetic radiation 102 by the device 100 differs from that of a gyrotron. Unlike the gyrotron-type interaction in which a spiral electron beam emits electromagnetic radiation, the interaction here is a Cerenkov-type interaction.
[0026] In a Cherenkov-type interaction, EM radiation 102 is generated by the deceleration of electron beam 106 due to the electromagnetic field excited and maintained inside waveguide 110. When relying on a Cherenkov-type interaction, it is not necessary to use a helical electron beam, and other types of electron beams can be used, as described in more detail below.
[0027] In the high-Q cavity (defined by the interaction region) of the device 100, the resonance may be very sharp, so that adjustments (as previously described) may be required to bring the electron beam 106 into a resonant condition, which clearly depends on the longitudinal velocity (i.e., Cherenkov-type interaction) of the electron beam 106. During adjustments, the shape of the electron beam 106 and the longitudinal and transverse velocities may need to be modified (e.g., increasing the transverse velocity, decreasing the longitudinal velocity, or making any other suitable changes) to tune the electron beam 106 into the resonant state.
[0028] The cylindrical structure may have an appropriate configuration to promote Cerenkov-type interactions, as described in more detail below.
[0029] The device 100 also includes an output coupler 112 that is configured to output the electromagnetic radiation 102 from the device 100. For example, the output coupler 112 may include a reflector that is configured to reflect at the operating wavelength of the device 100. The output coupler 112, which is dedicated to a particular operating mode, can be positioned to reflect the electromagnetic radiation 102 while also allowing the electron beam 106 to pass through to the rear portion of the device 100. For example, the reflector can be annular, allowing the electron beam 106 to pass through its center and reflect an annular beam profile of the electromagnetic radiation 102. Another configuration of the reflector can be a Vlasov-type mode converter. The design and position of the output coupler 112 may depend on various parameters, such as the beam profile of the electron beam 106, the operating mode structure, and any other parameters that can affect the beam profile of the electromagnetic radiation 102.
[0030] The apparatus 100 also includes an electron beam dump 114 that is configured to collect the electron beam 106 after the interaction region and recover energy from the electron beam 106. For example, the electron beam dump 114 can include a buck collector, such as a multi-stage buck collector (MDC). After the electron beam 106 has passed through the interaction region, the electron beam dump 114 can (via circuitry, not shown) recover energy from the electron beam 106. The amount of energy recovered from the electron beam 106 plays a role in determining the energy efficiency of the apparatus 100, as any recovered energy can be used to reduce the energy input to the apparatus 100 to produce a given power of EM radiation 102.
[0031] Thus, while there are similarities between device 100 and a gyrotron, there are some differences. The electromagnetic radiation 102 generated by device 100 is based on a Cerenkov-type interaction with an electron beam 106, rather than a gyrotron-type interaction. One of the differences between device 100 and a gyrotron includes the provision of a waveguide 110 in the interaction region.
[0032] Interest in generating electromagnetic radiation based on Cherenkov-type interactions for high-power applications has been limited because such techniques can have relatively low efficiencies. For example, efficiencies of 20-30% at lower frequencies and 10% at higher frequencies can be achieved using techniques based on Cherenkov-type interactions. Consequently, the trend in the field has been to use gyrotrons for high-power applications and other devices such as BWOs and TWTs for low-power applications.
[0033] However, the present disclosure identifies the possibility of obtaining higher-than-expected energy efficiency gains by exploiting such Cerenkov-type interactions.
[0034] As previously mentioned, the energy efficiency that can be achieved by a gyrotron is limited (e.g., up to 55%). A significant factor contributing to this limitation is the characteristics of the electron beam in the gyrotron and the design of the electron beam collector (e.g., a multi-stage step-down collector). The energy from the helical motion of the electron beam in a gyrotron is relatively difficult to recover, which places a practical limit on the energy recovery level possible from an MDC coupled to a gyrotron.
[0035] However, due to the different types of interactions that generate electromagnetic radiation 102, apparatus 100 can utilize such a helical electron beam without significant reliance, which offers the potential for utilizing a more efficient electron beam dump. The disclosure demonstrates that energy recovery is higher (e.g., greater than 55%, and potentially greater than 60%) when utilizing a Cerenkov-type interaction facilitated by waveguide 110 in combination with a more efficient electron beam dump that does not rely heavily on a helical electron beam. Cerenkov-type interactions are often not considered efficient enough for high-power applications in the art, and therefore this combination of waveguide 110 and electron beam dump 114 has not previously been considered.
[0036] Thus, the apparatus 100 and related embodiments can increase the overall efficiency of the electromagnetic radiation source 102 in the 10 GHz to 10 THz range while making the source more stable and reliable. The design of the apparatus 100 allows components to be supplied in a modular fashion, thereby making production and servicing more affordable. Thus, the apparatus 100 can: help reduce the cost of manufacturing and servicing operations; increase the overall efficiency to over 60%, thereby reducing the input energy required to sustain a fusion reaction; and / or provide greater reliability due to the apparatus 100 being less sensitive to the external environment.
[0037] Some embodiments related to the apparatus 100 will now be described.
[0038] Figure 2 2 is a schematic diagram of a waveguide 210 used in an apparatus such as apparatus 100, and reference is made to this figure in the following description. As previously described, the function of the waveguide 210 is to facilitate Cerenkov-type interactions. In this manner, the waveguide 210 forms a cavity (i.e., a resonator) within which the generation of the EM radiation 102 occurs. The electron beam 106 is decelerated in the field within the cavity, thereby generating electromagnetic radiation based on the Cerenkov principle. To achieve efficient interaction between the EM field within the cavity and the electron beam 106, pumping of the electron beam in transverse (i.e., circular) motion is not required, which results in most of the energy in the electron beam 106 being in the translational (i.e., longitudinal) direction. After interacting in the interaction region, the electron beam propagates to the electron beam collector 114, where more efficient energy recovery can occur.
[0039] Figure 2(A) Depicts the cylindrical structure of the waveguide 210. A coordinate system is established to assist in explaining the structural features of the waveguide 210. The longitudinal direction refers to the z-axis. The azimuthal direction is specified by the azimuthal coordinate φ, which defines an angular measurement along a given radial direction from the longitudinal axis of the cylindrical structure. The radius r refers to the distance from the origin / center of the cylindrical structure (defined by the longitudinal axis) to the inner surface 216 of the waveguide 210. When integrated with the device 100, the cylindrical structure is coaxial with the propagation axis of the electron beam 106, which passes through the hollow portion of the cylindrical structure.
[0040] The inner surface 216 of the waveguide 210 is configured to promote Cerenkov type interactions and allow the selection of high order modes with large diameters. High order modes are those with a large amount of radial or azimuthal variation, i.e., modes such as those generated by E m,n , where m(and / or)n is significantly greater than 1, i.e., m(n)>>1. For example, in the case of a waveguide 210 having an average diameter D and an operating wavelength λ, satisfying the condition D / λ>3, the number of azimuthal angle variations can be m≥5 and / or n≥5. Furthermore, the waveguide 210 is configured to support interaction of the electron beam 106 stream with an EM field (i.e., the eigenmodes of the cavity), which is excited and sustained by the design of the waveguide 210. The waveguide 210 (cavity) can be considered a surface field cavity because the interaction between the electron beam 106 and the waveguide 210 induces a surface EM field in the waveguide 210, which serves to decelerate the electron beam 106 and thereby radiate EM radiation 102.
[0041] The waveguide 210 may comprise a metal (e.g., copper, silver, etc.) or composite cylindrical structure (comprising a highly conductive material, such as a metal, and a less conductive material, the less conductive material providing support for the highly conductive material) having periodic perturbations in both the longitudinal (along the electron beam propagation) and azimuthal directions. The periodic perturbations are designed to suppress the motion of electrons within the conductive material in certain directions, thereby increasing the impedance of the waveguide 210 compared to a cylindrical structure without such perturbations. These periodic perturbations cause the radius r to vary with both the longitudinal and azimuthal coordinates. These periodic perturbations can restrict the motion of free electrons in both the longitudinal and azimuthal directions (in other words, increase the impedance), which results in the excitation of specific cavity eigenmodes (fields) within the waveguide 210. These eigenmodes act on the electron beam 106, thereby causing the electron beam 106 to decelerate and generate corresponding EM radiation 102.
[0042] Thus, in some embodiments, the inner surface 216 includes a two-dimensional periodic structure that is configured such that a radial distance r between a longitudinal axis of the cylindrical structure and a position on the inner surface 216 varies with the longitudinal coordinate and azimuthal coordinate of the position on the inner surface. Figure 2(B) depicts an example (but not limited to) of such a two-dimensional periodic structure, which depicts a checkerboard pattern on the inner surface 216. The checkerboard pattern represents a two-dimensional periodic structure. Figure 2 (C) indicates Figure 2 (B) Cross-sectional view of the two-dimensional periodic structure shown. Figure 2 (C) The curvature of the cylindrical structure is not depicted. It is therefore apparent that the inner surface 216 comprises a series of periodic perturbations in its two-dimensional surface structure. Figure 2 A rectangular-type periodic structure is depicted, having two possible levels (eg, heights) relative to the mean radius of the cylindrical structure.
[0043] Thus, in some embodiments, the inner surface 216 has a periodic surface height variation that varies in two dimensions along the inner surface 216 .
[0044] Other types of two-dimensional periodic structures, such as those based on sinusoidal (e.g., wavy) waves, may be used in the waveguide 210. For example, the radius r of the inner surface 216 may be given by the expression Definition, where r0 is the average radius of the cylindrical structure, r1 is the amplitude of the surface height variation of the two-dimensional periodic structure, z is the longitudinal coordinate, is the longitudinal period of the two-dimensional periodic structure, is the number of azimuthal variations of the two-dimensional periodic structure, and φ is the azimuthal coordinate.
[0045] In some cases, a cylindrical structure can be manufactured by machining the surface of a metal sheet to have any of the two-dimensional periodic structures described above, and then rolling the sheet into a cylindrical structure with the machined surface on the inside of the cylindrical structure.
[0046] The amplitude / depth of the surface height variation / perturbation can be in the range of 0.1 to 10 operating wavelengths of the device 100 to allow electromagnetic waves to form a field within the cylindrical structure. Thus, in some embodiments, the amplitude of the surface height variation is 0.1 to 10 times the operating wavelength of the device 100. The operating wavelength λ is related to the frequency component f, for example, by the expression c=fλ, where c is the speed of light.
[0047] In some embodiments, inner surface 216 includes a conductor such as metal and is configured to increase the impedance of waveguide 210 in the longitudinal and azimuthal directions along the cylindrical structure. The two-dimensional periodic structure described above is an example of a structure that increases the impedance of waveguide 210.
[0048] The lateral dimensions of the cavity, such as diameter D, can be determined relative to the operating wavelength λ, which can be in the range of 3 cm to 30 μm. The diameter D can be in the range of D / λ = 3 ... 1000, which can allow for maintaining a low power density to support continuous wave (CW) high power operation of the device 100 in a reliable manner within the output power range of 0.1 MW to 10 MW. Increasing the interaction region diameter alone without adding waveguide 210 can result in the termination of stable single-mode operation. Therefore, the additional waveguide 210 can help support stable single-mode operation with high power output and low power density.
[0049] Therefore, in some embodiments, the diameter D of the cylindrical structure satisfies the condition D / λ > 3, where λ is the operating wavelength of the device. In other words, the ratio of the diameter D to the operating wavelength λ is greater than 3. The operating wavelength is related to the frequency component. The diameter can refer to the average diameter of the cylindrical structure. A parameter relationship of D / λ > 3 has not been previously used. Other parameter relationships are also possible, such as D / λ > 4, 4.1, ..., 5, 5.1, ..., 10, ..., 1000.
[0050] In some embodiments, the apparatus 100 is configured to output electromagnetic radiation 102 at an average power exceeding: 250 kW in the frequency range of 10 GHz to 300 GHz; 1 kW in the frequency range of 300 GHz to 1 THz; and / or 100 W in the frequency range exceeding 1 THz. The use of the waveguide 210 as described above facilitates such high power operation within certain frequency ranges.
[0051] In some embodiments, apparatus 100 is configured to output continuous wave electromagnetic radiation 102 .
[0052] In some embodiments, device 100 is configured to output pulsed wave electromagnetic radiation 102 .
[0053] In some embodiments, the device is used to heat plasma in a fusion reaction system. In some embodiments, the device is used for large-area monitoring and environmental monitoring. In some embodiments, the device is used for quality assessment of large-area composite materials.
[0054] In some embodiments, most of the energy of the electron beam 106 is in a laminar flow (eg, linear flow) state.
[0055] In the case where the electron beam 106 is in the interaction region, the electron beam profile can be annular, as in the case of a gyrotron. However, most of the total energy of the electron beam is in the translational direction, rather than the circumferential (transverse) direction. Therefore, in some embodiments, the electron beam has more than 75% of its energy in a laminar state and less than 25% of its energy in a circular motion state. As previously discussed, it may be easier to recover energy from a laminar electron beam than from a spiral electron beam. By having more of the energy in the electron beam exist in a laminar state, the overall energy efficiency can be improved because more energy can be recovered from these electrons.
[0056] Figure 3 is a schematic diagram of a fusion reaction system 320 according to one embodiment. The fusion reaction system 320 includes a chamber 322 configured to confine plasma (e.g., based on a tokamak design or any other suitable design). The fusion reaction system 320 also includes an apparatus 300 (e.g., having Figure 1 The apparatus 300 may be configured to heat the plasma. In this regard, the apparatus 300 may be operatively coupled to the chamber 322 such that the chamber 322 receives the electromagnetic radiation.
[0057] Figure 4 Refers to a method 400 for generating electromagnetic radiation according to an embodiment. The generated electromagnetic radiation includes frequency components in the frequency range of 10 GHz to 10 THz. The following description refers to Figure 1 .
[0058] The method 400 includes, at block 402 , generating an electron beam 106 ;
[0059] The method 400 also includes, at block 404 , generating a magnetic field to direct the electron beam 106 within the interaction region where the electromagnetic radiation 102 is generated.
[0060] The method 400 further includes, at block 406, using the waveguide 110 including the cylindrical structure to facilitate a Cerenkov-type interaction between the electron beam 106 and an electromagnetic field excited and sustained within the waveguide 110 to produce the electromagnetic radiation 102. The cylindrical structure is coaxially aligned with the electron beam 106 in the interaction region;
[0061] The method 400 also includes, at block 408 , outputting the electromagnetic radiation 102 .
[0062] The method 400 also includes, at block 410 , collecting the electron beam 106 after the interaction region to recover energy from the electron beam 106 .
[0063] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.
[0064] One or more features described in one embodiment may be combined with or substituted for features described in another embodiment.
[0065] Elements or steps associated with one embodiment may be combined with or replaced with elements or steps associated with another embodiment. Those skilled in the art can understand and implement variations of the disclosed embodiments in practicing the claimed invention from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope.
Claims
1. A device (100) configured to generate electromagnetic radiation (102), the electromagnetic radiation comprising frequency components in the frequency range of 10 GHz to 10 THz, the device comprising: an electron source (104) configured to generate an electron beam (106); a magnetic field generator (108) configured to generate a magnetic field to condition and direct the electron beam within an interaction region where the electromagnetic radiation (102) is generated; a waveguide (110) comprising a cylindrical structure, wherein the cylindrical structure is coaxially aligned with the electron beam in the interaction region, and wherein an inner surface (216) of the cylindrical structure is configured to promote a Cerenkov-type interaction between the electron beam and an electromagnetic field excited and sustained inside the waveguide to produce the electromagnetic radiation; an output coupler (112) configured to output the electromagnetic radiation from the device; and An electron beam collector (114) is configured to collect the electron beam after the interaction region and to recover energy from the electron beam.
2. The device according to claim 1, wherein The inner surface includes a two-dimensional periodic structure configured such that a radial distance between a longitudinal axis of the cylindrical structure and a location on the inner surface varies with the longitudinal and azimuthal coordinates of the location on the inner surface.
3. The device according to any one of claims 1 to 2, wherein: The inner surface has periodic surface height variations that vary in two dimensions along the inner surface.
4. The device according to claim 3, wherein The amplitude of the surface height variation is in the range of 0.1 to 10 operating wavelengths of the device, wherein the operating wavelength is related to the frequency component.
5. The device according to any one of claims 1 to 4, wherein: The inner surface includes a conductor, and wherein the inner surface is configured to increase an impedance of the waveguide in a longitudinal direction and an azimuthal direction along the cylindrical structure.
6. The device according to any one of claims 1 to 5, wherein: The diameter D of the cylindrical structure satisfies the condition D / λ>3, where λ is the operating wavelength of the device, wherein the operating wavelength is related to the frequency component.
7. The device according to any one of claims 1 to 6, wherein: The device is configured to output electromagnetic radiation at an average power exceeding: 250kW in the 10GHz to 300GHz frequency range; 1 kW in the 300 GHz to 1 THz frequency range; and / or 100W, in the frequency range above 1THz.
8. The device according to any one of claims 1 to 7, wherein The device is configured to output continuous wave electromagnetic radiation or pulsed wave electromagnetic radiation.
9. The device according to any one of claims 1 to 8, wherein The device is used to heat plasma in a fusion reaction system.
10. The device according to any one of claims 1 to 9, wherein Most of the energy of the electron beam is in a laminar flow state.
11. The device according to claim 10, wherein More than 75% of the energy of the electron beam is in a laminar flow state, and less than 25% of the energy of the electron beam is in a circular motion state.
12. A fusion reaction system (320), comprising: a chamber (322) configured to confine a plasma; and The apparatus (300) of any one of claims 1 to 11, wherein the electromagnetic radiation output by the apparatus is configured to heat the plasma.
13. A method (400) for generating electromagnetic radiation, the electromagnetic radiation comprising frequency components in a frequency range of 10 GHz to 10 THz, the method comprising: generating (402) an electron beam; generating (404) a magnetic field to condition and direct the electron beam within an interaction region where the electromagnetic radiation is generated; using (406) a waveguide comprising a cylindrical structure to facilitate a Cerenkov-type interaction between the electron beam and an electromagnetic field excited and maintained within the waveguide to produce the electromagnetic radiation, wherein the cylindrical structure is coaxially aligned with the electron beam in an interaction region; outputting (408) the electromagnetic radiation; and The electron beam is collected (410) after the interaction region to recover energy from the electron beam.
14. A waveguide (110) for use in a device (100) configured to generate electromagnetic radiation comprising frequency components in the frequency range of 10 GHz to 10 THz, wherein: The waveguide comprises a cylindrical structure, wherein an inner surface (216) of the cylindrical structure is configured to promote a Cerenkov type interaction between an electron beam generated by the device and an electromagnetic field excited and maintained inside the waveguide to generate the electromagnetic radiation, wherein the cylindrical structure is coaxially aligned with the electron beam in a magnetic field interaction region for conditioning and guiding the electron beam, wherein the electromagnetic radiation will be generated in the magnetic field interaction region, wherein a diameter D of the cylindrical structure satisfies the condition D / λ>3, wherein D / λ>3 is a wavelength associated with a frequency component.
15. The waveguide according to claim 14, wherein The inner surface includes a two-dimensional periodic structure configured such that a radial distance between a longitudinal axis of the cylindrical structure and a location on the inner surface varies with the longitudinal and azimuthal coordinates of the location on the inner surface.
16. The waveguide according to any one of claims 14 to 15, wherein The inner surface has periodic surface height variations that vary in two dimensions along the inner surface.
17. A waveguide according to any one of claims 14 to 16, wherein The inner surface includes a conductor, and wherein the inner surface is configured to increase an impedance of the waveguide in a longitudinal direction and an azimuthal direction along the cylindrical structure.