CN112769024A - C-band relativistic Cerenkov oscillator with coaxial collector - Google Patents
C-band relativistic Cerenkov oscillator with coaxial collector Download PDFInfo
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Abstract
The invention relates to a microwave source device in the technical field of high-power microwaves, in particular to a C-band relativistic Cerenkov oscillator with a quasi-coaxial collector, belonging to the technical field of high-power microwaves; the device comprises a cathode seat, a cathode, an anode outer cylinder, a stop neck, a resonant reflection cavity, a slow wave structure, a drift section, an extraction cavity, a collector drift section, a collector inclined plane, a collector inner cavity, a collector baffle, an output waveguide and a solenoid magnetic field; the invention overcomes the problem that the conventional relativistic Cerenkov oscillator is difficult to consider both the long-output microwave pulse width and the high-power conversion efficiency, realizes the long-pulse-width and high-efficiency microwave output under the condition of using 6-period non-uniform slow-wave blades, and has the advantages of simple structure, easy processing and easy frequency repetition operation.
Description
Technical Field
The invention relates to a microwave source device in the technical field of high-power microwaves, in particular to a C-band relativistic Cerenkov oscillator with a quasi-coaxial collector, and belongs to the technical field of high-power microwaves.
Background
High power microwave generally refers to electromagnetic wave with peak power more than 100MW and frequency between 1GHz and 300 GHz, and the high power microwave technology is an emerging research field accompanied with the development of pulse power technology, plasma physics and electric vacuum technology. Has bright application prospect in the aspects of plasma heating, high-power radar, particle radio frequency acceleration and utilization of future space energy.
The high power microwave source is the core device of the high power microwave system, and its operation is based on coherent radiation of electron beam. The coherent radiation mechanism of the electron beam is classified into cerenkov radiation, transit radiation and bremsstrahlung radiation. The high-power microwave source based on the Cerenkov radiation mechanism is mainly a relativistic Cerenkov oscillator and a relativistic Cerenkov amplifier. The high-power microwave source based on the transition radiation mechanism is mainly a relativistic klystron oscillator and a relativistic klystron amplifier. The high-power microwave source based on the bremsstrahlung mechanism is mainly free electron laser, a virtual cathode and the like.
Relativistic cerenkov oscillators are one of the most promising high power microwave source devices at present. The coherent microwave radiation device utilizes the interaction of a relativistic electron beam and an electromagnetic wave mode (structural wave) in a slow wave structure to generate self oscillation and amplification to form coherent microwave radiation, and has the characteristics of high power, high efficiency, suitability for repeated frequency work and the like. Nowadays, improving the power conversion efficiency of the device and extending the pulse width of the output microwave have become important directions for the development of the device. The higher output power can be obtained under the same input power by improving the beam wave action efficiency of the device, and the longer microwave output can be obtained under the same input electrical length by prolonging the pulse width of the output microwave. Both are favorable for saving energy and obtaining a more practical and miniaturized high-power microwave system.
Research on Long Pulse relativity Cerenkov oscillators is typically a device designed by the university of defense Science and technology [ Jun Zhang, Zhen-Xing Jin, Jian-Hua Yang, Hui-Huang Zhong, Ting Shu, Jian-De Zhang, Bao-Liang Qian, Cheng-Wei Yuan, Zhi-Qiang Li, Yu-Wei Fan, Sheng-Yue Zhou, and Liu-Rong xu. The structure comprises a cathode seat, a cathode, an anode outer cylinder, a stop neck, a slow wave structure, a tapered waveguide, an output waveguide and a solenoid magnetic field, wherein the whole structure is rotationally symmetrical about a central axis. For convenience of description, the side closer to the cathode holder in the axial direction will be referred to as the left end, and the side farther from the cathode holder will be referred to as the right end hereinafter. Wherein the slow wave structure comprises 5 slow wave blades, and the internal surface of every slow wave blade all is the trapezium structure, and 4 slow wave blades on the left side are the same completely, and the 5 th slow wave blade has great biggest outer radius, the length L of 5 slow wave blades1The same is true. The output waveguide has an inner radius of R7The residual electrons are collected by the inner wall of the waveguide. The device has a simple structure, is beneficial to stable output of high-power microwaves, collects residual electrons by adopting the output waveguide with a larger radius, reduces the density of electrons at the collection position, reduces the quantity of secondary electrons generated by electron bombardment on the inner wall of the output waveguide, further weakens the influence of plasma on the microwaves, and is beneficial to realizing long-pulse operation. The experimental result shows that the microwave output power reaches 1GW, the pulse width is 100ns, and the frequency is 3.6 GHz. However, the power conversion efficiency of the device is low, only 20%, and is lower than the power conversion efficiency of about 30% of the conventional relativistic Cerenkov oscillator. The microwave with the same power is output, and the lower power conversion efficiency requires the pulse driving source to inject higher electric power, so that the higher requirement is provided for the driving capability of the pulse driving source, and the structure is not beneficial to be compact. Therefore, the technical scheme cannot realize the high efficiency of the long-pulse relativistic Cerenkov oscillatorOperation is not conducive to achieving miniaturization and compactness of high power microwave systems.
There are various ways to improve the power conversion efficiency of the relativistic cerenkov oscillator, such as adopting a non-uniform slow wave structure, adding a resonant cavity, adopting plasma loading, etc. Liu Guest, Chengchang, Zhang Yulong, the coaxial extraction relativistic backward wave tube, intense laser and particle beam, 2001, Vol.13, No.4, pp.467-470 (referred to as prior art 2 below) discloses a structure of a coaxial extraction relativistic Cerenkov oscillator. The slow wave structure in this structure comprises 9 slow wave blades, and the internal surface of every slow wave blade all is the trapezium structure, and 8 slow wave blades on the left side are identical, and the 9 th slow wave blade has great biggest outer radius, the length L of 9 slow wave blades1The same is true. The coaxial extraction relativistic backward wave tube also comprises a cylindrical coaxial extraction structure, wherein an annular groove is dug in the left end face of the coaxial extraction structure, and residual electrons are absorbed by the inner wall of the groove. Because the structure is only a numerical simulation model which is preliminarily established, the connection mode of the coaxial extraction structure and the output waveguide is not handed over. The result of the particle simulation shows that the output microwave power is 2.0GW, the frequency is 9.28GHz, and the efficiency reaches 45%. However, in the simulation result of this device, the output power contains a dc component, and thus the simulation result has a large error. The slow wave structure of the device adopts 9 slow wave blades, so that the axial length is overlarge, and the miniaturization of the device is not facilitated. In addition, the device intends to utilize the inner wall of the groove on the left side of the coaxial extraction structure to absorb residual electrons, so that secondary electrons generated by electron beams directly bombarding the inner wall of the output waveguide are reduced, the influence of the secondary electrons on the working process of the device is further weakened, and the long-pulse output of microwaves is realized. However, after the electron beams are bombarded for a long time, the temperature of the stainless steel material on the inner wall of the groove is easily increased, and then plasma is generated, which affects the work of the device. The coaxial extraction structure is located inside the device, so that water circulation is not easy to cool, and the long-pulse and repeated-frequency work of the relativistic Cerenkov oscillator is not facilitated.
Long pulses and high efficiency are the goals sought by microwave source designers, although relativistic cerenkov oscillators have been studied for many years, it is still challenging to compromise long microwave pulses and high efficiency.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the invention provides a C-band relativistic Cerenkov oscillator with a similar coaxial collector, which adopts the similar coaxial collector with an extraction cavity to improve the microwave extraction efficiency, inhibit the plasma diffusion of the collector, overcome the problem that the conventional relativistic Cerenkov oscillator is difficult to consider both the long-output microwave pulse width and the high-power conversion efficiency, realize the long-pulse width and high-efficiency microwave output under the condition of using six-period non-uniform slow-wave blades, and have the advantages of simple structure, easy processing and easy frequency repetition operation.
The technical scheme of the invention is as follows:
a C-band relativistic Cerenkov oscillator with a similar coaxial collector comprises a cathode base 301, a cathode 302, an anode outer cylinder 303, a cut-off neck 304, a resonant reflection cavity 305, a slow wave structure 306, a drift section 307, an extraction cavity 308, a collector drift section 309, a trapezoidal collector 310, a collector inner cavity 311, a collector baffle 312, an output waveguide 313 and a solenoid magnetic field 314, wherein the collector drift section 309, the trapezoidal collector 310, the collector inner cavity 311 and the collector baffle 312 form the similar coaxial collector; the whole structure is rotationally symmetrical about a central axis, the left end of the cathode base 301 is externally connected with an anode of a pulse power source, the left end of the anode outer cylinder 303 is externally connected with an outer conductor of the pulse power source, and the right end of the output waveguide 313 is connected with the mode converter and the antenna;
the cathode 302 is a thin-walled cylinder with a wall thickness of 1mm and an inner radius R1Equal to the radius of the electron beam, and sleeved at the right end of the cathode base 301; the stop neck 304 is disk-shaped and has an inner radius R2，R2＞R1Length L between the cutoff neck 304 and the cathode 3021Called the distance between the anode and cathode, L1Too small results in premature expansion of the cathode plasma to the anode resulting in a shorter cathode-anode closing pulse, so L1Typically greater than 2 cm; the resonant reflective cavity 305 is disk-shaped with an inner radius R2And an outer radius R3Satisfy R3＞R2Length L of3The value is generally 0.4 to 0.5 times of the working wavelength lambda; length from resonant reflective cavity 305Is L12Is a slow wave structure 306, L12The value is generally 0.5 to 1 time of the working wavelength lambda; the slow-wave structure 306 is composed of 6 trapezoidal slow-wave blades, and the length of each trapezoidal slow-wave blade is L5All inner radii are R2The ring of (2); the first slow-wave blade is in a right-angle trapezoid shape, and the length of the upper bottom of the trapezoid is L4The width of the bevel edge is L13The outer radius of the slow-wave blade is R4(ii) a The second, third and fifth slow wave blades are isosceles trapezoids, and the length of the upper base of the trapezoid is L4The width of the bevel edge is L13The outer radius of the slow-wave blade is R5、R6、R8Satisfy R8>R6>R5(ii) a The fourth trapezoidal slow wave blade has the length of L at the upper bottom6Satisfy L6>L4The width of the bevel edge is L15And L16Satisfy L16>L15The outer radius of the slow wave blade is R7Satisfy R7>R8(ii) a The sixth slow wave blade is also in the shape of a right trapezoid, and the length of the upper bottom of the trapezoid is L4The width of the bevel edge is L13The outer radius of the slow wave blade is R9Satisfy R7>R9>R8；L4And L5The value is generally 0.1 times of the working wavelength lambda; the slow-wave structure 306 is followed by a section of inner radius R2Length of L7Drift section 307, the length L of drift section 3077Affecting the match, L, between the slow wave structure 306 and the extraction cavity 3087Typically 1to 1.2 times the operating wavelength λ; the drift section 307 is connected with an extraction cavity 308, the extraction cavity 308 is disc-shaped, and the outer radius is R10Length of L8Satisfy R10>R7The outer radius and depth of the extraction cavity determine the microwave extraction effect of the extraction cavity 308, and the depth is the outer radius R of the extraction cavity10And inner radius R of drift section2A difference of (d); the extraction cavity 308 is followed by a quasi-coaxial collector, which is composed of a collector drift section 309, a trapezoidal collector 310, a collector inner cavity 311 and a coaxial cylinder 312: the collector drift section 309 is connected behind the extraction cavity 308 and has a length L9And an outer radius of R11Inner radius of R13The ring of (1) satisfies R11>R2>R13(ii) a The trapezoidal collector 310 is connected to the collector drift section 309 and is a ring with a right trapezoid cross section, and the inner and outer radii of the upper bottom of the trapezoid are R13And R11The inner and outer radii of the lower sole are R respectively13And R12Height is L10Satisfy R12>R11>R13High L of10The reflection of the collector on the electromagnetic wave is influenced, and is generally 0.2-0.5 times of the working wavelength; the collector cavity 311 is connected to the rear of the trapezoidal collector 310 and has an outer radius R12Inner radius of R13Length is L11The ring of (1) satisfies R12>R13Length L of collector cavity11The partial reflection of the electromagnetic wave in the quasi-coaxial collector is generally 0.8 to 1 time of the working wavelength; the collector baffle 312 is formed by digging out the collector drift section 309, the trapezoidal collector 310 and the collector inner cavity 311 to form an inner radius R14An outer radius of R13The ring can prevent plasma generated by electron bombardment of the collector from diffusing to other positions of the device, and meets the requirement of R13>R14(ii) a The output waveguide 313 has a radius R14The left end face of the circular waveguide is flush with the left end face of the quasi-coaxial collector, and the length of the circular waveguide is 3-5 times of the working wavelength.
The cathode base 301, the anode outer cylinder 303, the slow wave structure 306, the collector baffle 312 and the output waveguide 313 are all made of stainless steel, the cathode 302 is made of graphite, and the solenoid magnetic field 314 is formed by winding copper wires.
Compared with the prior art, the invention can achieve the following technical effects:
(1) the quasi-coaxial collector with the extraction cavity is adopted, and the main functions are as follows:
(a) the output microwave power comparison with and without an extraction cavity of the device is shown in fig. 6. After the extraction cavity is adopted, the radius of the extraction cavity is large, and a strong standing wave field exists in the cavity, so that the electron beam can be modulated and lose energy by the standing wave field in the extraction cavity when passing through the extraction cavity, the lost energy of the electron beam is given to microwaves, and the microwave energy extracted is improved, so that the output microwave power can be improved by adopting the extraction cavity;
(b) the device adopts a quasi-coaxial collector and a circular waveguide collector, the output microwave power comparison graph is shown in figure 7, compared with the circular waveguide collector, the quasi-coaxial collector is provided with a coaxial sheath structure at the electron beam bombardment position, the intracavity reflection characteristic is changed, the intracavity symmetric mode growth rate is influenced, and according to the existing research result, the output microwave power is obviously improved after the quasi-coaxial collector is added. (ii) a
(c) After the collector was filled with 1torr of gas, a comparative graph of output power with and without the co-axial collector of the device is shown in fig. 8. The microwave output power is reduced by 150MW for devices employing a quasi-coaxial collector after an ionized gas layer is provided at the collector. However, devices that do not employ a co-axial collector have a reduced microwave output power by more than 1GW with time dependent variation in output microwave power after the ionized gas layer is provided at the collector. This is because the quasi-coaxial collector reduces the axial electric field near the electron beam bombardment position, and therefore, the number and speed of charged particles moving in the axial direction are reduced, and the effect of suppressing the pulse shortening effect is obtained. Meanwhile, the coaxial cylinder prevents the charged particles moving in the radial direction from entering the output waveguide area, so that the passing rate of the transmitted microwaves is improved, and the microwave output efficiency is improved;
(d) length L of drift segment7The effect on microwave power and efficiency is shown in FIG. 9, where L is selected in the preferred embodiment7The length is 8.2cm, and the following advantages are achieved: 1. by adjusting the distance L between the extraction cavity and the slow-wave structure7The phase of the structural wave between them can be adjusted, preferably L7The reflection of the structural wave is enhanced, and the beam wave action efficiency is improved. 2. The collector and the slow-wave structure are longer in distance, the influence of the plasma diffusion of the collector on the beam wave action in the slow-wave structure is smaller, and the long-pulse operation of the device is facilitated;
(e) the drift section of the collector is 1cm long, the trapezoid collector is 3cm long, namely the distance between the electron beam bombardment position and the extraction cavity is 4 cm. The large spacing distance is beneficial to increasing the time for the plasma of the collector to diffuse to the extraction cavity, reducing the influence of the pulse shortening effect on the device and improving the stable operation time of the device;
(f) the simulation long pulse experiment of the quasi-coaxial collector with the extraction cavity is shown in fig. 10, and after the quasi-coaxial collector with the extraction cavity is adopted, a device can stably run for about 116ns in the simulation experiment, microwaves are stably output, and no obvious pulse shortening phenomenon occurs.
(2) With a resonant reflector cavity, the main effects are as follows:
the resonant reflecting cavity can reflect return microwave and isolate the beam wave action area and the diode area. S of resonant reflective cavity at different frequencies21Parameter values S at 4.30GHz as shown in FIG. 1121The parameter value can be-19 dB, and the resonant reflection cavity plays a good reflection role.
(3) A segmented non-uniform slow wave structure is adopted, and the main functions are as follows:
(a) in the process that the slow wave structure is transited from the rectangular structure to the trapezoidal structure, the distance between the conductor tips on the two sides of the cavity is gradually increased, the local field enhancement at the conductor tips can be avoided, and the risk of strong field breakdown is reduced. As the inclination angle of the trapezoid decreases, the electrostatic field induced by the electron beam increases gradually, which suppresses the field emission of electrons from the metal surface.
(b) When saturation is reached (t is 49ns), a comparison graph of the modulation current of the device adopting a uniform slow wave structure and a non-uniform slow wave structure along with the change of the axial position is shown in fig. 12, and the modulation current amplitude of the device adopting the non-uniform slow wave structure is obviously higher than that of the device adopting the uniform slow wave structure. When a uniform slow wave structure is adopted, energy is partially given to electromagnetic waves by the electron beams at the rear section of the slow wave structure, the speed of the electron beams is lower than the phase speed of spatial harmonics, and the energy cannot be fully converted. When the non-uniform slow wave structure is adopted, the coupling impedance can be increased by improving the ripple depth at the rear end of the slow wave structure, and the harmonic phase speed is reduced. When the speed of the electron beam is reduced, the phase speed of the structural wave is correspondingly reduced, so that the rear part of the slow wave structure can still meet the good beam synchronization condition.
(c) The output microwave spectrogram adopting the non-uniform slow-wave structure is shown in fig. 13, and therefore, the operation main frequency component is higher, and the frequency doubling stray frequency is lower. The non-uniform slow wave structure can carry out frequency selection and restrain frequency doubling and mixed frequency components through matching among high-frequency structures with different depths.
Drawings
Fig. 1 is a schematic diagram of the structure of a relativistic cerenkov oscillator disclosed in prior art 1 in the background introduction;
fig. 2 is a schematic diagram of the structure of a relativistic cerenkov oscillator disclosed in prior art 2 in the background introduction;
FIG. 3 is a schematic cross-sectional view A-A of a preferred embodiment of a C-band high efficiency relativistic backward wave oscillator using a quasi-coaxial collector according to the present invention;
FIG. 4 is a partial schematic diagram of an extraction cavity-co-axial-like collector of a preferred embodiment of a C-band high efficiency relativistic backward wave oscillator employing a co-axial-like collector provided in the present invention;
FIG. 5 is a schematic sectional A-A perspective view of a preferred embodiment of a C-band high efficiency relativistic backward wave oscillator employing a quasi-coaxial collector according to the present invention;
FIG. 6 is a comparison graph of axial net power flow with and without an extraction cavity for a preferred embodiment of a C-band high efficiency relativistic backward wave oscillator employing a quasi-coaxial collector provided by the present invention;
FIG. 7 is a graph comparing axial net power flow with and without a coaxial collection structure for a preferred embodiment of a C-band high efficiency relativistic backward wave oscillator employing a coaxial-like collector provided in accordance with the present invention;
FIG. 8 is a comparative graph of output power of a C-band high-efficiency relativistic backward wave oscillator using a quasi-coaxial collector according to a preferred embodiment of the invention, after the collector is provided with an ionized gas layer with a gas pressure of 1torr, with or without the quasi-coaxial collector;
FIG. 9 is a diagram of the output power and frequency of the device of the preferred embodiment of the C-band high-efficiency relativistic backward wave oscillator with the coaxial-like collector according to the invention, as a function of the distance L between the slow wave structure and the extraction cavity7A variation graph of (2);
FIG. 10 is a diagram of the results of a long pulse simulation experiment of a preferred embodiment of a C-band high efficiency relativistic backward wave oscillator employing a quasi-coaxial collector according to the present invention;
FIG. 11 is a preferred embodiment resonant reflector S of a C-band high efficiency relativistic backward wave oscillator employing a coaxial-like collector according to the present invention21A graph;
fig. 12 is a comparison graph of modulation current with axial position change when a uniform slow wave structure and a non-uniform slow wave structure are adopted when microwaves of a preferred embodiment of a C-band high-efficiency relativistic backward wave oscillator provided by the invention adopt a quasi-coaxial collector reach saturation (t is 49 ns);
fig. 13 is a graph of the output microwave spectrum of a preferred embodiment of a C-band high efficiency relativistic backward wave oscillator using a quasi-coaxial collector according to the present invention.
Detailed Description
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention.
Fig. 1 is a schematic diagram of a structure of a long-pulse relativistic cerenkov oscillator disclosed in prior art 1. The structure comprises a cathode seat 101, a cathode 102, an anode outer cylinder 103, a stop neck 104, a slow wave structure 105, a tapered waveguide 106, an output waveguide 107 and a solenoid magnetic field 108, and the whole structure is rotationally symmetrical about a central axis. Wherein slow wave structure 5 comprises 5 slow wave blades, and the internal surface of every slow wave blade all is the trapezium structure, and 4 slow wave blades on the left side are identical, and the biggest external radius is R3The minimum inner radius is R4(ii) a The maximum outer radius of the 5 th slow wave blade is R3The minimum inner radius is R5Average radius of R6Satisfy R3＞R6＞R5＞R4Length L of 5 slow-wave blades1The same is true. The output waveguide 107 has an inner radius of R7The residual electrons are collected by the inner wall of the waveguide. The scheme has a simple structure, realizes the long-pulse high-power microwave output with the pulse width of 100ns in an experiment, and has important reference significance for developing a long-pulse relativity Cerenkov oscillator. However, the power conversion efficiency of the device is low, only 20%, lower than the power conversion efficiency of 30% of the conventional relativistic Cerenkov oscillator, and notThe high-efficiency operation of the long-pulse relativistic Cerenkov oscillator can be realized, the miniaturization and the compactness of a high-power microwave system are not facilitated, and the expansion of the application range of the high-power microwave system is influenced.
Fig. 2 is a schematic diagram of a structure of a high-efficiency relativistic cerenkov oscillator disclosed in prior art 2. Although the paper discloses the composition of the structure, the structure is only a preliminarily established numerical simulation model, and there is no specific technical solution. The structure comprises a cathode seat 201, a cathode 202, an anode outer cylinder 203, a stop neck 204, a slow wave structure 205, a tapered waveguide 206, an output waveguide 207, a solenoid magnetic field 208 and a coaxial extraction structure 209, wherein the whole structure is rotationally symmetrical about a central axis. Wherein slow wave structure 205 comprises 9 slow wave blades, and the internal surface of every slow wave blade all is the trapezium structure, and 8 slow wave blades on the left side are the same completely, and the biggest external radius is R3The minimum inner radius is R4(ii) a The maximum outer radius of the 9 th slow-wave blade is R3The minimum inner radius is R5Average radius of R6Satisfy R3＞R6＞R5＞R4. Length L of 9 slow-wave blades1The same is true. The output waveguide has an inner radius of R7The circular waveguide of (1). The coaxial extraction structure 9 has an outer radius R8The left end surface of the coaxial extraction structure 209 is dug with an annular groove, and the inner radius R of the annular groove9And an outer radius R10Satisfy R10＞R1＞R9And residual electrons are absorbed by the inner wall of the groove. Since the structure is only a preliminarily established numerical simulation model, the connection mode of the coaxial extraction structure 209 and the output waveguide 207 is not handed over. A simulation model is established by using the scheme, the output microwave power is 2.0GW, the frequency is 9.28GHz, the efficiency reaches 45 percent (higher than the power conversion efficiency of 30 percent of the conventional relativistic Cerenkov oscillator) through simulation, and the method has important reference significance for developing the high-efficiency relativistic Cerenkov oscillator. However, in the simulation result of this device, the output power contains a dc component, and thus the simulation result has a large error. The device adopts 9 slow-wave structures 205, which results in too large axial length and is not beneficial to miniaturization of the device. In addition, the device is intended to utilize the left side of the coaxial extraction structure 209The inner wall of the groove absorbs residual electrons, so that secondary electrons generated by electron beams directly bombarding the inner wall of the output waveguide 207 are reduced, the influence of the secondary electrons on the working process of a device is weakened, and the long-pulse output of microwaves is realized. However, after the electron beam is bombarded for a long time, the temperature of the stainless steel material on the inner wall of the groove is easily increased, and then plasma is generated, so that the beam wave action process inside the device is influenced, and pulse shortening is caused. Since the coaxial extraction structure 209 is located inside the device, it is not easy to cool by water circulation, so it is not beneficial to the operation of the relativistic cerenkov oscillator with long pulse and repetition frequency.
Fig. 3 is a schematic sectional structure view of a-a cross section of a preferred embodiment of a relativistic backward wave oscillator using a quasi-coaxial collector provided by the present invention, fig. 4 is a partial schematic sectional view of an extraction cavity-quasi-coaxial collector of a preferred embodiment of a C-band high-efficiency relativistic backward wave oscillator using a quasi-coaxial collector provided by the present invention, and fig. 5 is a schematic sectional perspective view of a-a cross section of the present embodiment. The invention is composed of a cathode base 301, a cathode 302, an anode outer cylinder 303, a stop neck 304, a resonant reflection cavity 305, a slow wave structure 306, a drift section 307, an extraction cavity 308, a collector drift section 309, a trapezoidal collector 310, a collector inner cavity 311, a collector baffle 312, an output waveguide 313 and a solenoid magnetic field 314, wherein the whole structure is rotationally symmetrical about a central axis, the left end of the cathode base 301 is externally connected with an inner conductor of a pulse power source, the left end of the anode outer cylinder 303 is externally connected with an anode of the pulse power source, and the right end of the output waveguide 313 is connected with a mode converter and a radiation antenna.
This embodiment implements a C-band high efficiency relativistic cerenkov oscillator (correspondingly dimensioned: R) with a center frequency of 4.32GHz (corresponding to a microwave wavelength λ of 7cm)1＝43mm，R2＝48mm，R3＝61mm，R4＝53mm，R5＝53mm，R6＝56mm，R7＝64mm，R8＝57mm，R9＝58mm，R10＝71mm，R11＝49mm，R12＝54mm，R13＝42mm，R14＝38mm，L1＝21mm，L2＝44mm，L3＝31mm，L4＝6mm，L5＝6mm，L6＝8mm，L7＝83mm，L8＝14mm，L9＝10mm，L10＝30mm，L11＝60mm，L12＝10mm，L13＝8mm，L14＝8mm，L15＝7mm，L16＝8mm，L 17100 mm). In the particle simulation, under the conditions of diode voltage 680kV, current 12.4kA and guiding magnetic field 1.2T, microwave power 3.5GW, power conversion efficiency 42% and pulse width 116ns (electric pulse width 130ns) are output. From the above results, the present invention overcomes the disadvantage that the relativistic Cerenkov oscillator can only singly pursue high efficiency or long pulse, and can obtain high efficiency and long pulse output.
Referring to fig. 6, it can be seen that the electromagnetic wave power is greatly increased at the extraction cavity with the extraction cavity 308 compared to the case without the extraction cavity. The addition of the extraction cavity facilitates the extraction of electron beam energy into the electromagnetic wave.
Referring to fig. 7, it can be seen that compared with the circular waveguide collector, the collector baffle 312 of the quasi-coaxial collector (collector drift section 309, trapezoidal collector 310, collector cavity 311, collector baffle 312) changes the reflection characteristic in the cavity, thereby affecting the growth rate of the symmetric mode in the cavity and significantly increasing the output microwave power.
Referring to fig. 8, it can be seen that the microwave output power is reduced by 150MW after the ionized gas layer is disposed at the collector in the device using the co-axial collector. However, devices that do not employ a co-axial collector have a reduced microwave output power by more than 1GW with time dependent variation in output microwave power after the ionized gas layer is provided at the collector. So in the preferred embodiment a quasi-coaxial collector is used.
See FIG. 9 for the drift distance L7When L is shown in the figure7When the length is changed from 0.2cm to 10cm, the efficiency of microwave output by the device is periodically changed, and the competition frequency appears when the efficiency of the device is low, so L7Is critical. In when L7When the length is 7.2cm-9.2cm, the frequency of the output microwave is constant at 4.32GHz, the efficiency of the output microwave has an extreme value in the interval, and when L is within the range7This extreme value is taken at a length of 8.2 cm. Therefore select L7Length 8.2cm as the inventionPreferred values of the preferred embodiment.
Referring to fig. 10, it can be seen from the graph that when the rising edge 40ns, the falling edge 40ns, and the pulse width 130ns of the input power are simulated, the output microwave pulse width is about 116ns, the output microwave curve is stable after saturation, and no obvious pulse shortening phenomenon occurs, which is favorable for outputting long-pulse microwaves.
Referring to FIG. 11, it can be seen that at a frequency of 4.30GHz, the S of the resonant reflective cavity 30521The value is-19 dB and the resonant reflective cavity performs a good reflective function.
Referring to fig. 12, it can be seen that compared with the case of the non-uniform slow-wave structure 306, the modulation current amplitude of the uniform slow-wave structure is lower, the number of the electron beam clusters is small, and the beam transduction capability is low. Therefore, in order to enhance the clustering of the electron beams and improve the beam wave action efficiency, the preferred embodiment adopts a non-uniform slow wave structure.
Referring to fig. 13, it can be seen that the output microwave frequency is 4.30GHz, the frequency spectrum is relatively pure, there are no spurious frequencies, and the frequency multiplication component is relatively small.
Of course, in the preferred embodiment, other connection modes may be adopted among the cut-off neck 304, the resonant reflective cavity 305, the slow-wave structure 306, the drift section 307, the extraction cavity 308, the quasi-coaxial collectors (the collector drift section 309, the trapezoidal collector 310, the collector internal cavity 311, the collector baffle 312), and the output waveguide 313, and the device structure may be processed by using other materials.
It will be clear to a person skilled in the art that the scope of the present invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the present invention as defined in the attached claims. While the invention has been illustrated and described in detail in the drawings and the description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments.
Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the term "comprising" does not exclude other steps or elements. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims shall not be construed as limiting the scope of the invention.
Claims (3)
1. The utility model provides a C wave band relativity cheenkov oscillator of band class coaxial collector which characterized in that: the collector comprises a cathode base (301), a cathode (302), an anode outer cylinder (303), a cut-off neck (304), a resonant reflection cavity (305), a slow wave structure (306), a drift section (307), an extraction cavity (308), a collector drift section (309), a trapezoidal collector (310), a collector inner cavity (311), a collector baffle (312), an output waveguide (313) and a solenoid magnetic field (314), wherein the collector drift section (309), the trapezoidal collector (310), the collector inner cavity (311) and the collector baffle (312) form a similar coaxial collector; the whole structure is rotationally symmetrical about a central axis, the left end of the cathode base (301) is externally connected with an anode of a pulse power source, the left end of the anode outer cylinder (303) is externally connected with an outer conductor of the pulse power source, and the right end of the output waveguide (313) is connected with the mode converter and the antenna;
the cathode (302) is a thin-walled cylinder with a wall thickness of 1mm and an inner radius R1Equal to the radius of the electron beam, and sleeved at the right end of the cathode base (301); the stop neck (304) is in the shape of a disk with an inner radius R2，R2＞R1Length L between the cutoff neck (304) and the cathode (302)1Called the distance between the anode and cathode, L1Too small results in premature expansion of the cathode plasma to the anode resulting in a shorter cathode-anode closing pulse, L1Greater than 2 cm; the resonant reflective cavity (305) is in the shape of a disk with an inner radius R2And an outer radius R3Satisfy R3＞R2Length L of3The value is 0.4-0.5 times of the working wavelength lambda; a length L from the resonant reflective cavity (305)12Is a slow wave structure 306, L12The value is 0.5 to 1 time of the working wavelength lambda; the slow wave structure (306) is composed of 6 trapezoidal slow wave blades connected with the trapezoidal slow wavesThe blades are all L in length5All inner radii are R2The ring of (2); the first slow-wave blade is in a right-angle trapezoid shape, and the length of the upper bottom of the trapezoid is L4The width of the bevel edge is L13The outer radius of the slow-wave blade is R4(ii) a The second, third and fifth slow wave blades are isosceles trapezoids, and the length of the upper base of the trapezoid is L4The width of the bevel edge is L13The outer radius of the slow-wave blade is R5、R6、R8Satisfy R8>R6>R5(ii) a The fourth trapezoidal slow wave blade has the length of L at the upper bottom6Satisfy L6>L4The width of the bevel edge is L15And L16Satisfy L16>L15The outer radius of the slow wave blade is R7Satisfy R7>R8(ii) a The sixth slow wave blade is also in the shape of a right trapezoid, and the length of the upper bottom of the trapezoid is L4The width of the bevel edge is L13The outer radius of the slow wave blade is R9Satisfy R7>R9>R8；L4And L5The value is 0.1 times of the working wavelength lambda; the slow wave structure (306) is followed by a section of inner radius R2Length of L7The drift section (307), the length L of the drift section (307)7Influencing the matching between the slow-wave structure (306) and the extraction cavity (308), L7The value is 1to 1.2 times of the working wavelength lambda; the drift section (307) is connected with an extraction cavity (308) in back, the extraction cavity (308) is in a disc shape, and the outer radius is R10Length of L8Satisfy R10>R7The external radius and the depth of the extraction cavity determine the microwave extraction effect of the extraction cavity (308), and the depth is the external radius R of the extraction cavity10And inner radius R of drift section2A difference of (d); the extraction cavity (308) is followed by a quasi-coaxial collector, which comprises a collector drift section (309), a trapezoidal collector (310), a collector inner cavity (311) and a coaxial cylinder (312): the collector drift section (309) is connected behind the extraction cavity (308) and has a length L9And an outer radius of R11Inner radius of R13The ring of (1) satisfies R11>R2>R13(ii) a The trapezoidal collector (310) is connected behind the collector drift section (309) and has a straight sectionThe inner and outer radii of the upper bottom of the trapezoid are R respectively13And R11The inner and outer radii of the lower sole are R respectively13And R12Height is L10Satisfy R12>R11>R13High L of10The reflection of the collector on the electromagnetic wave is influenced and is 0.2-0.5 times of the working wavelength; the collector inner cavity (311) is connected behind the trapezoidal collector (310) and has an outer radius of R12Inner radius of R13Length is L11The ring of (1) satisfies R12>R13Length L of collector cavity11The partial reflection of the electromagnetic wave in the quasi-coaxial collector is related, and the working wavelength is 0.8 to 1 time; the collector baffle (312) is formed by digging out the collector drift section (309), the trapezoidal collector (310) and the collector inner cavity (311) to form an inner radius R14An outer radius of R13The ring can prevent plasma generated by electron bombardment of the collector from diffusing to other positions of the device, and meets the requirement of R13>R14(ii) a The output waveguide (313) has a radius of R14The left end face of the circular waveguide is flush with the left end face of the quasi-coaxial collector, and the length of the circular waveguide is 3-5 times of the working wavelength.
2. A C-band relativistic cerenkov oscillator with a coaxial collector according to claim 1, wherein: the cathode base (301), the anode outer cylinder (303), the slow wave structure (306), the collector baffle (312) and the output waveguide (313) are all made of stainless steel, the cathode (302) is made of graphite, and the solenoid magnetic field (314) is formed by winding copper wires.
3. A C-band relativistic cerenkov oscillator with a coaxial collector according to claim 1 or 2, wherein: the C-band high efficiency relativistic cerenkov oscillator with a center frequency of 4.32GHz is correspondingly dimensioned: r1＝43mm，R2＝48mm，R3＝61mm，R4＝53mm，R5＝53mm，R6＝56mm，R7＝64mm，R8＝57mm，R9＝58mm，R10＝71mm，R11＝49mm，R12＝54mm，R13＝42mm，R14＝38mm，L1＝21mm，L2＝44mm，L3＝31mm，L4＝6mm，L5＝6mm，L6＝8mm，L7＝83mm，L8＝14mm，L9＝10mm，L10＝30mm，L11＝60mm，L12＝10mm，L13＝8mm，L14＝8mm，L15＝7mm，L16＝8mm，L17＝100mm。
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| CN115241719A (en) * | 2022-07-21 | 2022-10-25 | 中国人民解放军国防科技大学 | Cross-four-band relativity Cerenkov oscillator based on magnetic field tuning |
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