CN117856744A - High-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction - Google Patents
High-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction Download PDFInfo
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Abstract
The invention discloses a high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction, which comprises the following components: the Ku wave band pre-modulation area is used for pre-modulating and bunching the strong current relativistic electron beams, and realizes the fundamental current pre-modulation depth and the frequency doubling current pre-modulation depth which are not lower than 80%; a Ka band energy extraction region for effecting efficient conversion of beam-wave energy; aiming at the problem of high sensitivity of high-frequency band phase-locked HPM source size parameters, the invention adopts a Ku-band electron beam pre-modulation structure to replace a Ka-band electron beam pre-modulation structure adopted in the prior art, and the working frequency of an electron beam pre-modulation area is reduced by one half; correspondingly, the size parameter of the electron beam pre-modulation area is doubled, and the parameter sensitivity is obviously reduced; the invention researches the high frequency problem in the low frequency range, and can effectively improve the error tolerance of the Ka-band phase-locked HPM source.
Description
Technical Field
The invention relates to the technical field of high-power microwave source devices, in particular to a high-power microwave amplifier for frequency multiplication extraction by fundamental frequency modulation.
Background
High power microwaves (High Power Microwave, HPM) generally refer to electromagnetic waves having peak powers greater than 100MW and frequencies between 1 and 300 GHz. The pursuit of higher power, higher frequency, higher efficiency microwave output is an important development goal in the HPM technology field. Through more than fifty years of research and development, several typical HPM devices can realize GW-level HPM output, but the output power of a single HPM generating device is difficult to further improve due to physical mechanisms such as radio frequency breakdown, space charge effect and the like and limitations of factors such as materials, processing technology and the like, and N can be obtained in a far field by coherent synthesis of microwaves generated by a plurality of HPM sources through a coherent synthesis technology 2 A multiple of peak power density (N is the number of high power microwave sources) is expected to achieve equivalent HPM radiation on the order of hundreds of GWs.
The triaxial relativity klystron amplifier (Triaxial Klystron Amplifier, TKA) is an HPM source based on an electron beam distribution modulation theory, utilizes mutually independent beam-wave interaction resonant cavity structures to realize modulation, bunching and beam-wave energy conversion of electron beams, can realize HPM output with stable frequency and controllable phase, and is one of preferred devices for realizing high-frequency band HPM coherent synthesis. At present, TKA has realized the HPM output of GW-level frequency locking phase lock in the X-band and Ku-band, however, when TKA operating frequency expands to a higher frequency band, the device is difficult to realize high-power microwave output, for example, a Ka-band TKA proposed by researchers simulates output power of 1.17GW, only 776kW of microwave output is obtained in experiments, and experimental power is less than one thousandth of simulation power, which is specifically referred to existing document 1: LI S, DUAN Z, HUANG H, et al extended interaction oversized coaxial relativistic klystron amplifier with gigawatt-level output at Ka band [ J ]. Physics of Plasmas,2018,25 (4): 983.
The main problems faced by the Ka-band TKA are analyzed as follows:
(1) Narrow channel long distance electron beam transport problem: in order to realize the cut-off of the working mode, the width of the TKA drift tube needs to be controlled within 0.5λ (λ is the output microwave wavelength); meanwhile, the modulation and the clustering of the intense current relativistic electron beams (Intense Relativistic Electron Beam, IREB) in TKA are carried out separately, and a longer drift section is needed to realize the deep clustering of IREB. Thus, in the Ka band TKA, the IREB needs to be transmitted over a long distance in a narrow channel. The IREB scratches the drift channel even at a guiding magnetic field strength of 1.0T, with the risk of beam loss. Unstable insufficient transmission of IREB will result in reduced microwave power output by the device;
(2) Radio frequency breakdown problem: the high-frequency band TKA has small volume size and low power capacity, and under the high-power operation condition, the surface field intensity of the front cavity and the extraction cavity is extremely easy to exceed the breakdown threshold value of the cavity material, so that radio frequency breakdown occurs; the radio frequency breakdown can cause the formation of an anode plasma source, electrons and ions which are continuously emitted by the anode plasma source can diffuse along a magnetic induction line, collide with IREB and obstruct the transmission of the IREB, and finally cause the problems of reduced device efficiency, shortened pulse, mode jump and the like;
(3) Low error tolerance problem: TKA belongs to a coaxial device, and the eccentric and misplacement of an inner conductor and an outer conductor are extremely easy to cause due to processing and assembly errors, so that the resonance parameters of each beam-wave interaction resonant cavity of the device deviate from design parameters, the deviation of the parameters can lead to the deviation of the optimal modulation position of IREB, even the serious reduction of the modulation depth of fundamental wave current is caused, and the output microwave power of the device is reduced. The problem of low error tolerance is essentially due to the higher sensitivity of TKA to the beam-wave interaction resonator operating characteristics, which is more pronounced in the high frequency band.
In order to realize Ka-band coherent power synthesis, a three-axis relativity klystron amplifier (see existing document 2, patent number: ZL 202210720087.4) adopting a slow wave extraction device is provided by national defense university KOGHW researchers and the like in combination with the phase locking characteristic of TKA and the high power capacity characteristic of an overmode slow wave structure, and the specific structure is shown in figure 1; according to the scheme, the coaxial slow wave extraction structure is adopted to replace the coaxial extraction cavity of the TKA, so that the problem that the frequency and the phase of output microwaves are difficult to lock due to free competition of the eigenmodes of the slow wave structure can be solved, and the effective improvement of the power capacity of the triaxial relativity klystron amplifier can be realized. However, the coaxial slow wave extraction structure is only used for beam-wave energy conversion, the typical TKA modulation structure is still adopted for IREB modulation and clustering, and the device still faces the narrow-channel long-distance electron beam transmission problem. In order to solve the problem of narrow-channel long-distance electron beam transmission, a Ka-band phase-locked speed-adjusting coaxial Cerenkov device (see existing document 3, patent application number: 202310957303.1) is proposed by national defense university Zhang Wei lecturer and the like, and the specific structure is shown in FIG. 2; according to the scheme, a coaxial Cherenkov device is adopted to replace a coaxial slow wave extraction structure in the prior art 2, HPM output of frequency locking and phase locking can be achieved only by providing 30% of fundamental wave current pre-modulation depth, on one hand, the length of an electron beam pre-modulation area is shortened, and then effective shortening of the electron beam transmission distance is achieved, and on the other hand, the outer corrugated inner smooth waveguide structure adopted in the prior art 3 can effectively reduce the parameter sensitivity of an energy extraction area of the device, and then error tolerance is improved. However, the prior art 3 includes two parts, i.e., a "pre-modulation region" and an "energy extraction region", and only improves the parameter sensitivity of the "energy extraction region", but cannot effectively solve the "low error tolerance" problem faced by the Ka-band phase-locked HPM source.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction, which solves the problem that the low error tolerance problem faced by a Ka-band phase-locked HPM source cannot be effectively solved in the prior art, and the high-frequency problem is researched in a low-frequency range, so that the error tolerance of the Ka-band phase-locked HPM source can be effectively improved.
In order to achieve the above object, the technical scheme of the present invention is as follows:
the invention provides a high-power microwave amplifier for frequency multiplication extraction of fundamental frequency modulation, which comprises a Ku wave band pre-modulation region and a Ka wave band energy extraction region; for convenience of description, the left side of the structure is referred to as an input end, and the right side is referred to as an output end; the input end of the Ku wave band pre-modulation area is connected with a pulse power source, the output end of the Ku wave band pre-modulation area is connected with the input end of the Ka wave band energy extraction area, and the output end of the Ka wave band energy extraction area is connected with an antenna.
As an aspect of the high-power microwave amplifier of the present invention, it further comprises an inner conductor a and an outer conductor B rotationally symmetrical about the central axis; the annular cavity between the inner conductor A and the outer conductor B is a drift tube; the drift tube comprises a first drift segment and a second drift segment, wherein the first drift segment is positioned in the Ku wave band pre-modulation region, and the second drift segment is positioned in the Ka wave band energy extraction region.
As one aspect of the high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction, the Ku band pre-modulation region comprises an injection cavity, a first modulation cavity, a second modulation cavity, a first reflection cavity and a second reflection cavity; the injection cavity is used for high-efficiency absorption of the Ku wave band injection microwave power and primary modulation of electron beams; the first modulation cavity and the second modulation cavity are used for further modulating the electron beam, so that the fundamental current pre-modulation depth and the frequency multiplication current pre-modulation depth which are not lower than 80% are realized; the first reflecting cavity and the second reflecting cavity are used for isolating adjacent beam-wave interaction resonant cavities, ensuring stable operation of the device and inhibiting growth of parasitic modes.
As one aspect of the high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction, the injection cavity is of a re-entry type structure with an energy feed-in ring at one side, the re-entry type structure is formed by combining a circular drift tube coupling section and a circular re-entry section, the energy feed-in ring is of a disc-shaped structure, the right side of the energy feed-in ring and the right side of the circular re-entry section are provided with length distances, the lower side of the energy feed-in ring is in die-to-die connection with the injection cavity, and the injection cavity is in die-to-die conversion into an HPM amplifier structure; the first reflecting cavity and the first modulating cavity are of adjacent annular structures, and axial distances are arranged between the first reflecting cavity and the first modulating cavity; the left side of the first reflecting cavity and the right side of the coupling section of the circular drift tube are provided with axial distances; the second reflecting cavity and the second modulating cavity are of adjacent annular structures, and axial distances are arranged between the second reflecting cavity and the second modulating cavity; and the left side of the second reflecting cavity and the right side of the first modulating cavity are provided with axial intervals.
As one aspect of the high-power microwave amplifier extracted by fundamental frequency modulation and frequency multiplication, the injection cavity, the first modulation cavity and the second modulation cavity all adopt a single-gap circular ring resonant cavity structure, and mode competition is restrained by utilizing the active restraining characteristic of the single-gap resonant cavity to non-rotational symmetrical mode self-excited oscillation; the working modes of the injection cavity, the first modulation cavity and the second modulation cavity are TM 011 The mode, the operating frequency belongs to Ku band.
As an aspect of the high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction, the Ka-band energy extraction area comprises a third reflection cavity and a slow wave extraction structure, wherein the third reflection cavity is used for isolating the Ku-band pre-modulation area and the Ka-band energy extraction area, so that each part can work independently and stably; the slow wave extraction structure is used for realizing high-efficiency conversion of beam-wave energy; and the right sides of the third reflecting cavity and the second modulating cavity are provided with axial spacing.
As an aspect of the high-power microwave amplifier for frequency multiplication extraction of fundamental frequency modulation, the slow wave extraction structure comprises an outer corrugated structure arranged on the outer conductor B and a smooth waveguide structure arranged on the inner conductor a, and the slow wave extraction structure is used for reducing the parameter sensitivity of the device on the premise of ensuring the high-power capacity characteristic of the high-frequency band HPM device; the slow wave extraction structure working mode comprises a TEM mode and a TM mode 01 A mold using TEM mold and TM 01 Mode coupling of the modes suppresses mode competition; the slow wave extraction structure is a periodic uniform slow wave structure, and the periodic uniform slow wave structure can adopt a rectangular corrugated structure, a trapezoid corrugated structure or a cosine corrugated structure; the slow wave extractionThe operating frequency of the structure belongs to the Ka band.
As one aspect of the high-power microwave amplifier extracted by fundamental frequency modulation and frequency multiplication, the fundamental mode isolation of the first reflecting cavity and the second reflecting cavity is more than 500MHz, so that mode competition caused by mutual coupling between reflectors can be effectively prevented; the third reflection cavity and the slow wave extraction structure are provided with a circular ring structure with abrupt radius changes, and the circular ring structure is matched with the third reflection cavity for use, so that the pre-modulation area and the energy extraction area can be effectively isolated, and each part can be ensured to work independently and stably.
As one aspect of the high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction, the injection signal received by the injection cavity is in a Ku wave band, the first modulation cavity and the second modulation cavity can be modulated in cascade to improve the modulation depth of fundamental wave current and the modulation depth of frequency multiplication current at the same time, and the slow wave extraction structure can realize extraction of Ka wave band microwaves under excitation of frequency multiplication current.
According to TKA modulation cavity theory, the current modulated by the modulation cavity has rich harmonic components, and specifically: the harmonic current comprises a first-order harmonic current (fundamental wave current), a second-order harmonic current (frequency doubling current) and a third-order harmonic current … …, and the peak value of each harmonic current is gradually reduced; the invention utilizes two-stage cascade modulation cavities (the first modulation cavity and the second modulation cavity) to simultaneously improve the modulation depth of fundamental wave current and frequency doubling current, so that although the working frequency of the Ku wave band pre-modulation area belongs to the Ku wave band, the pre-modulation current comprises harmonic current of Ka wave band, and the harmonic current can excite the working mode of the Ka wave band energy extraction area; therefore, the injection microwaves of the high-power microwave amplifier extracted by fundamental frequency modulation and frequency multiplication are in a Ku wave band, and the output microwaves are in a Ka wave band, namely the invention realizes the Ku/Ka wave band frequency multiplication high-power microwave amplifier.
The working principle of the high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction is as follows: when an externally injected microwave signal is fed into the injection cavity, the coaxial TM is excited at the gap of the injection cavity 01 Mode in which an axial electric field initially irradiates a passing electron beamStep speed modulation; the speed modulation of the electron beam is deepened by the first modulation cavity and the second modulation cavity, so that the fundamental current pre-modulation depth and the frequency multiplication current pre-modulation depth which are not lower than 80% are realized; when the electron beam fully pre-modulated passes through the slow wave extraction structure, an alternating electric field with corresponding frequency is excited in the cavity, the electric field decelerates the electron beam, and the kinetic energy of the electron beam is converted into electromagnetic energy and coupled out; the injection signal received by the injection cavity is in a Ku wave band, the first modulation cavity and the second modulation cavity can be modulated in cascade to improve the modulation depth of fundamental wave current and the modulation depth of frequency doubling current at the same time, and the slow wave extraction structure can extract Ka wave band microwaves under the excitation of frequency doubling current.
By adopting the technical scheme, the invention has the following advantages:
the invention provides a high-power microwave amplifier for frequency multiplication extraction by fundamental frequency modulation, which adopts a Ku-band electron beam pre-modulation structure to replace a Ka-band electron beam pre-modulation structure adopted in the prior art, the injected microwaves of a device are Ku-band, the output microwaves are Ka-band, and the working frequency of an electron beam pre-modulation area is reduced by one half; the size parameter of the electron beam pre-modulation area in the Ku wave band is doubled, and the parameter sensitivity is obviously reduced; the high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction is used for researching the high-frequency problem in a low-frequency range, and can effectively improve the error tolerance of a Ka-band phase-locked HPM source.
Drawings
Fig. 1 is a diagram showing a triaxial relativity klystron amplifier using a slow wave extraction device disclosed in conventional document 2;
fig. 2 is a diagram of a structure of a Ka-band phase-locked klystron type coaxial coulkov device disclosed in prior art 3;
FIG. 3 is a diagram of a high power microwave amplifier with frequency multiplication extraction based on fundamental frequency modulation;
FIG. 4 is a block diagram of a Ku-band preconditioning zone of the present invention;
FIG. 5 is a block diagram of the Ka band energy extraction region of the present invention;
FIG. 6 is a graph of the output microwave power curve, time-frequency curve and time-phase curve of the high-power microwave amplifier of the present invention;
FIG. 7 is a graph of the output microwave power of the high power microwave amplifier of the present invention without externally injected microwaves;
FIG. 8 is a graph of the fundamental current and frequency doubled current distribution after the Ku band pre-modulation region modulation of the present invention;
fig. 9 is a time-frequency plot of the high power microwave amplifier of the present invention at different injection microwave frequencies.
Detailed Description
In the following detailed description of the embodiments of the present invention, reference is made to the accompanying drawings, in which it is to be noted that, in this document, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention provides a high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction, which particularly comprises a Ku wave band pre-modulation area and a Ka wave band energy extraction area, as shown in figure 3, wherein the Ku wave band pre-modulation area is used for pre-modulation and bunching of strong current relativity electron beams, and realizes the fundamental current pre-modulation depth and the frequency multiplication current pre-modulation depth which are not lower than 80%; the Ka band energy extraction region is used for realizing high-efficiency conversion of beam-wave energy.
For convenience of description, the left side of the high-power microwave amplifier structure extracted by frequency multiplication of fundamental frequency modulation is called an input end, and the right side is called an output end; the output end of the Ku wave band pre-modulation area is connected with the input end of the Ka wave band energy extraction area; the input end of the Ku band pre-modulation area is connected with a pulse power source, and the Ka band energy extraction area is connected with an antenna; the pulse power source and the antenna are common structures in the HPM field, and are not limited.
The high-power microwave amplifier with the fundamental frequency modulation frequency multiplication extraction further comprises an inner conductor A and an outer conductor B which are rotationally symmetrical with respect to a central axis, wherein a circular cavity between the inner conductor A and the outer conductor B is a drift tube, the drift tube comprises a first drift section and a second drift section, specifically, the drift tube positioned in a Ku wave band pre-modulation region is called a first drift section, and the drift tube positioned in a Ka wave band energy extraction region is called a second drift section; the inner radius of the first drift section is R1, and the outer radius of the first drift section is R2; the inner radius of the second drift section is R16, and the outer radius is R17; the inner conductor a and the outer conductor B may be made of a desired conductor material, such as aluminum, stainless steel, oxygen-free copper, or the like, as desired.
In a specific embodiment, the Ku band pre-modulation region is specifically shown in fig. 4, and includes an injection cavity 1, a first modulation cavity 3, a second modulation cavity 5, a first reflection cavity 2, and a second reflection cavity 4; the injection cavity 1 is used for high-efficiency absorption of Ku wave band injection microwave power and primary modulation of electron beams; the first modulation cavity 3 and the second modulation cavity 5 are used for further modulation of electron beams, and fundamental current pre-modulation depth and frequency multiplication current pre-modulation depth which are not lower than 80% are realized; the first reflective cavity 2 and the second reflective cavity 4 are used for isolating adjacent beam-wave interaction resonant cavities, ensuring stable operation of the device and inhibiting growth of parasitic modes. The injection cavity 1 is a re-entry structure with an energy feed-in ring at one side, and the re-entry structure is formed by combining a circular drift tube coupling section and a circular re-entry section; the inner radius of the coupling section of the circular drift tube is R3, the outer radius is R4, and the length is L3; the inner radius of the annular reentrant section is R3, the outer radius is R5, and the length is L5; the energy feed-in ring of the injection cavity 1 is of a disc-shaped structure, and the width of the energy feed-in ring is L7; the distance between the right side of the energy feed-in ring of the injection cavity 1 and the right side of the circular re-entry section is L6; the lower side of the energy feed-in ring of the injection cavity 1 is connected with an injection cavity die, and the injection cavity die is converted into a common structure of the HPM amplifier, and the embodiment is not repeated; the first reflecting cavity 2 and the first modulating cavity 3 are of adjacent annular structures and are used for first-stage amplification of fundamental wave modulating current; the inner radius of the first reflecting cavity 2 is R6, the outer radius is R7, and the length is L8; the inner radius of the first modulation cavity 3 is R8, the outer radius is R9, and the length is L10; the axial distance between the first reflecting cavity 2 and the first modulating cavity 3 is L9; the axial distance between the left side of the first reflecting cavity 2 and the right side of the coupling section of the circular drift tube of the injection cavity 1 is L1; the second reflecting cavity 4 and the second modulating cavity 5 are of adjacent annular structures and are used for second-stage amplification of fundamental wave modulating current; the inner radius of the second reflecting cavity 4 is R11, the outer radius is R10, and the length is L11; the inner radius of the second modulation cavity 5 is R12, the outer radius is R13, and the length is L13; the axial distance between the second reflecting cavity 4 and the second modulating cavity 5 is L12; the axial distance between the left side of the second reflective cavity 2 and the right side of the first modulation cavity 3 is L2.
The Ka band energy extraction area is specifically shown in FIG. 5, and comprises a third reflection cavity 6 and a slow wave extraction structure 7; the third reflecting cavity 6 is of a circular ring structure and is used for isolating a Ku wave band pre-modulation area and a Ka wave band energy extraction area and guaranteeing that all the parts work independently and stably; the radius of the third reflecting cavity 6 is R14, the outer radius is R15, and the length is L14; the axial distance between the third reflecting cavity 6 and the right side of the second modulating cavity 5 is L3; the slow wave extraction structure 7 is a periodic uniform slow wave structure and is used for realizing high-efficiency conversion of beam-wave energy; in order to improve the power capacity of the device, the slow wave extraction structure 7 adopts an outer corrugated structure, and an inner conductor adopts a smooth waveguide structure; specifically, in one specific embodiment, the slow wave extraction structure 7 is a seven-period external ripple rectangular slow wave structure disposed inside the second drift section; in practical application, the cycle number of the slow wave extraction structure 7 can be optimized according to practical application requirements, and the slow wave extraction structure 7 can adopt a rectangular corrugated structure, a trapezoid corrugated structure, a cosine corrugated structure and the like; the axial spacing between the right side of the third reflection cavity 6 and the left side of the second drift section is L15; the left axial distance between the left side of the second drift section and the left side of the slow wave extraction structure 7 is L16; in this embodiment, the slow wave extraction structure 7 is a seven-period rectangular outer corrugated structure, the inner radius is R18, the outer radius is R17, the period length is L17, and the thickness of the blade is L18;
according to TKA modulation cavity theory, the modulated current of the modulation cavity has abundant harmonic components, specifically comprises first-order harmonic current (fundamental wave current), second-order harmonic current (frequency doubling current) and third-order harmonic current … …, and simultaneously, the peak value of each-order harmonic current is gradually reduced; in the embodiment, the modulation depth of fundamental wave current and frequency doubling current is simultaneously improved by utilizing a two-stage cascade modulation cavity (a first modulation cavity 3+a second modulation cavity 5), so that although the working frequency of a Ku wave band pre-modulation area belongs to a Ku wave band, the pre-modulation current comprises harmonic current of a Ka wave band, and the harmonic current can excite the working mode of the Ka wave band energy extraction area; therefore, the injection microwave of the high-power microwave amplifier extracted by fundamental frequency modulation and frequency multiplication is in a Ku wave band, and the output microwave is in a Ka wave band, namely the embodiment realizes the Ku/Ka wave band frequency multiplication high-power microwave amplifier.
The working principle of the high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction is as follows: when an externally injected microwave signal is fed into the injection cavity 1, the coaxial TM is excited at the gap of the injection cavity 1 01 A mode in which an axial electric field primarily modulates the velocity of the passing electron beam; the speed modulation of the electron beam is deepened by the first modulation cavity 3 and the second modulation cavity 5, so that the fundamental current pre-modulation depth and the frequency multiplication current pre-modulation depth which are not lower than 80% are realized; when passing through the slow wave extraction structure 7, the electron beam fully pre-modulated excites an alternating electric field with corresponding frequency in the cavity, and the electric field decelerates the electron beam, converts kinetic energy of the electron beam into electromagnetic energy and couples out; the injection signal received by the injection cavity 1 is in Ku wave band, the first modulation cavity 3 and the second modulation cavity 5 are modulated in cascade, the modulation depth of fundamental wave current and the modulation depth of frequency doubling current can be improved at the same time, and the slow wave extraction structure 7 realizes extraction of microwaves in the Ka wave band under excitation of the frequency doubling current.
Fig. 6 shows an output microwave power curve, a time-frequency curve and a time-phase curve of a high-power microwave amplifier extracted by fundamental frequency modulation and frequency multiplication; as shown in fig. 6, in the present embodiment, the high-power microwave amplifier obtains 665MW HPM output under the conditions of 430kV electron beam voltage, 5.35kA current, 14.25GHz injection microwave frequency, 5kW injection microwave power, and 1.0T guiding magnetic field strength, the injection ratio is-51.2 dB, and the saturation time of the output microwave power is about 30ns; the output microwave frequency of the high-power microwave amplifier is stable to 28.50GHz, and the phase jitter is smaller than +/-5 degrees, so that the high-power microwave amplifier is proved to realize HPM output with frequency phase locking; meanwhile, the output microwave frequency of the device is twice of the injection microwave frequency, and therefore Ku/Ka band high-power microwave frequency multiplication amplification is achieved. In addition, the slow wave extraction structure 7 cannot self-oscillate and is only used for beam-wave energy conversion, i.e. the slow wave extraction structure 7 cannot independently form an HPM oscillator, and the slow wave extraction structure 7 cannot independently work under the condition of not providing a pre-modulation current; FIG. 7 shows the output microwave power curve of a high-power microwave amplifier extracted by frequency multiplication of fundamental frequency modulation without external injection of microwaves; as shown in fig. 7, under the condition of no external injection microwave, the output microwave power of the high-power microwave amplifier extracted by fundamental frequency modulation frequency multiplication is only in the order of tens kW, which is far lower than the power of the electron beam (2.3 GW), which indicates that the power microwave amplifier device cannot self-oscillate.
According to the TKA working principle, the drift tube width of TKA needs to be controlled within 0.5λ (λ is the output microwave wavelength) to realize a working mode (TM) 01 A die); for the high-power microwave amplifier for fundamental frequency modulation frequency multiplication extraction, the Ku wave band pre-modulation region and the Ka wave band energy extraction region are isolated from each other, so that the first drift section width (R2-R1) is only controlled to be within one half of the working wavelength (2.10 cm) of the Ku wave band pre-modulation region, and the device can stably work; however, the slow wave extraction structure 7 cannot self-oscillate, and the Ku band pre-modulation region is required to provide enough frequency multiplication pre-modulation current, and the larger the frequency multiplication pre-modulation current modulation depth is, the higher the microwave extraction efficiency of the slow wave extraction structure 7 is; according to TKA modulation cavity theory, the narrower the drift tube width is, the stronger the modulation capability of the electron beam of the modulation cavity is; therefore, the first drift section width (R2-R1) is controlled to be within one half of the operating wavelength (1.05 cm) of the Ka band energy extraction region; because the working frequency (28.50 GHz) of the Ka band energy extraction area is twice that of the Ku band pre-modulation area (14.25 GHz), the first drift section can simultaneously realize the cut-off of the Ku band pre-modulation area working mode and the Ka band energy extraction area working mode; meanwhile, under the condition that the width of the first drift section is smaller than one half of the working wavelength of the Ka band energy extraction region, the designed injection cavity 1, the first modulation cavity 3 and the second modulation cavity 5 all have higher fundamental wave current modulation capability; in the case of a typical Ku band TKA, the pilot magnetic field and the device power are consideredOn the premise of capacity, the width of the drift tube is generally one third of the working wavelength of the device and is larger than one half of the working wavelength of the Ka band energy extraction region.
FIG. 8 shows the fundamental and doubled current profiles after Ku band preconditioning zone modulation; as shown in fig. 8, the fundamental current and the frequency multiplication current after the Ku band pre-modulation region modulation are 6.56kA and 5.47kA, respectively, and the current modulation depth is 122.6% and 102.2%, respectively; fig. 9 shows the phase curves of high power microwave amplifiers extracted by frequency multiplication of fundamental frequency modulation at different injection microwave frequencies. As can be seen from fig. 9, in the range of 14.21 GHz-14.29 GHz of the injection microwave frequency, the output microwave frequency of the device is exactly twice the injection microwave frequency, that is, the invention can realize frequency multiplication high-power microwave amplification in the range of 14.21 GHz-14.29 GHz of the injection microwave frequency, and the output microwave frequency range is 28.42 GHz-28.58 GH; correspondingly, the phase locking bandwidth of the high-power microwave amplifier of the invention is about 160MHz.
In one embodiment, the structure-related parameters of a high-power microwave amplifier extracted by frequency multiplication of fundamental frequency modulation are as follows: the frequency of externally injected microwave signals is 14.25GHz, corresponding to the microwave wavelength lambda=2.10 cm; the frequency of the output microwave signal is 28.50GHz, and the relevant structural dimensions corresponding to the microwave wavelength lambda=1.05cm are as follows: r1=68 mm, r2=72mm, r3=63.6 mm, r4=75.6 mm, r5=66.0 mm, r6=60.0 mm, r7=80.1 mm, r8=64.4 mm, r9=75.5 mm, r10=78.5 mm, r11=62.0 mm, r12=64.6 mm, r13=75.3 mm, r14=65.5 mm, r15=74.6 mm, r16=63.8 mm, r17=72.5 mm, r18=71.0 mm, l1=32.2 mm, l2=22.0 mm, l3=28.3 mm, l4=5.6 mm, l5=19.4 mm, l6=6.0 mm, l7=2.0 mm, l8=9.8 mm, l9=4.0 mm, l10=7.0 mm, l11=6.0 mm, l3=12.0 mm, l3=9.9.8 mm, l1=9.8 mm, l6.8 mm, l3=9.8 mm, l1=8.8 mm, l3=8.8 mm.
In particular, the device pre-modulation area adopts a single-group or multi-group cascade current modulation structure, the modulation cavity adopts a single-gap or multi-gap structure, the energy extraction area adopts a single-section or multi-section slow wave structure, and all HPM amplifiers adopting 'fundamental frequency modulation' + 'frequency multiplication extraction' are within the protection scope of the invention.
Finally, it is pointed out that while the invention has been described with reference to a specific embodiment thereof, it will be understood by those skilled in the art that the above embodiments are provided for illustration only and not as a definition of the limits of the invention, and various equivalent changes or substitutions may be made without departing from the spirit of the invention, therefore, all changes and modifications to the above embodiments shall fall within the scope of the appended claims.
Claims (9)
1. The high-power microwave amplifier is characterized by comprising a Ku wave band pre-modulation area and a Ka wave band energy extraction area, wherein the input end of the Ku wave band pre-modulation area is connected with a pulse power source, the output end of the Ku wave band pre-modulation area is connected with the input end of the Ka wave band energy extraction area, and the output end of the Ka wave band energy extraction area is connected with an antenna.
2. The high-power microwave amplifier of claim 1, further comprising an inner conductor a and an outer conductor B rotationally symmetric about a central axis; the annular cavity between the inner conductor A and the outer conductor B is a drift tube; the drift tube comprises a first drift segment and a second drift segment, wherein the first drift segment is positioned in the Ku wave band pre-modulation region, and the second drift segment is positioned in the Ka wave band energy extraction region.
3. The high power microwave amplifier of claim 2, wherein the Ku band pre-modulation region comprises an injection cavity, a first modulation cavity, a second modulation cavity, a first reflection cavity, and a second reflection cavity; the injection cavity is used for high-efficiency absorption of the Ku wave band injection microwave power and primary modulation of electron beams; the first modulation cavity and the second modulation cavity are used for further modulating the electron beam, so that the fundamental current pre-modulation depth and the frequency multiplication current pre-modulation depth which are not lower than 80% are realized; the first reflecting cavity and the second reflecting cavity are used for isolating adjacent beam-wave interaction resonant cavities, ensuring stable operation of the device and inhibiting growth of parasitic modes.
4. The high-power microwave amplifier extracted by fundamental frequency modulation and frequency multiplication according to claim 3, wherein the injection cavity is of a re-entry type structure with an energy feed-in ring at one side, the re-entry type structure is formed by combining a circular drift tube coupling section and a circular re-entry section, the energy feed-in ring is of a disc-shaped structure, the right side of the energy feed-in ring and the right side of the circular re-entry section are provided with length distances, the lower side of the energy feed-in ring is in die-to-die connection with the injection cavity, and the injection cavity is in die-to-HPM amplifier common structure; the first reflecting cavity and the first modulating cavity are of adjacent annular structures, and axial distances are arranged between the first reflecting cavity and the first modulating cavity; the left side of the first reflecting cavity and the right side of the coupling section of the circular drift tube are provided with axial distances; the second reflecting cavity and the second modulating cavity are of adjacent annular structures, and axial distances are arranged between the second reflecting cavity and the second modulating cavity; and the left side of the second reflecting cavity and the right side of the first modulating cavity are provided with axial intervals.
5. The high-power microwave amplifier extracted by fundamental frequency modulation and frequency multiplication according to claim 4, wherein the injection cavity, the first modulation cavity and the second modulation cavity all adopt a single-gap circular ring resonant cavity structure, and mode competition is restrained by utilizing the active restraining characteristic of the single-gap resonant cavity to self-excited oscillation of a non-rotational symmetrical mode; the working modes of the injection cavity, the first modulation cavity and the second modulation cavity are TM 011 The mode, the operating frequency belongs to Ku band.
6. The high-power microwave amplifier for frequency multiplication extraction by fundamental frequency modulation according to claim 5, wherein the Ka-band energy extraction region comprises a third reflective cavity and a slow wave extraction structure, the third reflective cavity is used for isolating the Ku-band pre-modulation region and the Ka-band energy extraction region, and ensuring that each part works independently and stably; the slow wave extraction structure is used for realizing high-efficiency conversion of beam-wave energy; and the right sides of the third reflecting cavity and the second modulating cavity are provided with axial spacing.
7. The high-power microwave amplifier according to claim 6, wherein the slow wave extraction structure comprises an outer corrugated structure arranged on the outer conductor B and a smooth waveguide structure arranged on the inner conductor a, so as to reduce the sensitivity of device parameters on the premise of ensuring the high-power capacity characteristic of the high-frequency band HPM device; the slow wave extraction structure working mode comprises a TEM mode and a TM mode 01 A mold using TEM mold and TM 01 Mode coupling of the modes suppresses mode competition; the slow wave extraction structure is a periodic uniform slow wave structure, and the periodic uniform slow wave structure can adopt a rectangular corrugated structure, a trapezoid corrugated structure or a cosine corrugated structure; the working frequency of the slow wave extraction structure belongs to the Ka wave band.
8. The high-power microwave amplifier of claim 7, wherein the fundamental mode isolation of the first and second reflective cavities is greater than 500MHz, so as to effectively prevent mode competition caused by mutual coupling between reflectors; the third reflection cavity and the slow wave extraction structure are provided with a circular ring structure with abrupt radius changes, and the circular ring structure is matched with the third reflection cavity for use, so that the pre-modulation area and the energy extraction area can be effectively isolated, and each part can be ensured to work independently and stably.
9. The high-power microwave amplifier for fundamental frequency modulation and frequency multiplication extraction according to claim 1, wherein the injection signal received by the injection cavity is in a Ku band, the first modulation cavity and the second modulation cavity are modulated in cascade to simultaneously increase the modulation depth of fundamental wave current and the modulation depth of frequency multiplication current, and the slow wave extraction structure is used for realizing extraction of microwaves in the Ka band under excitation of frequency multiplication current.
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| US6700548B1 (en) * | 2002-09-27 | 2004-03-02 | Victory Industrial Corporation | Dual band antenna feed using an embedded waveguide structure |
| KR101686570B1 (en) * | 2016-09-06 | 2016-12-14 | 한만기 | Device and method for providing smart satelite internet zone using multi band antenna for satellite communication |
| CN116864358A (en) * | 2023-07-31 | 2023-10-10 | 中国人民解放军国防科技大学 | Ka-band phase-locked speed-adjusting coaxial Cerenkov device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US6700548B1 (en) * | 2002-09-27 | 2004-03-02 | Victory Industrial Corporation | Dual band antenna feed using an embedded waveguide structure |
| KR101686570B1 (en) * | 2016-09-06 | 2016-12-14 | 한만기 | Device and method for providing smart satelite internet zone using multi band antenna for satellite communication |
| CN116864358A (en) * | 2023-07-31 | 2023-10-10 | 中国人民解放军国防科技大学 | Ka-band phase-locked speed-adjusting coaxial Cerenkov device |
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