CN109243943B - Fast-adjusting relativistic backward wave tube working in local inhomogeneous magnetic field - Google Patents
Fast-adjusting relativistic backward wave tube working in local inhomogeneous magnetic field Download PDFInfo
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- CN109243943B CN109243943B CN201811119996.2A CN201811119996A CN109243943B CN 109243943 B CN109243943 B CN 109243943B CN 201811119996 A CN201811119996 A CN 201811119996A CN 109243943 B CN109243943 B CN 109243943B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
- H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
- H01J25/10—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator
- H01J25/16—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator with pencil-like electron stream perpendicular to the axis of the resonators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
- H01J23/02—Electrodes; Magnetic control means; Screens
- H01J23/08—Focusing arrangements, e.g. for concentrating stream of electrons, for preventing spreading of stream
- H01J23/087—Magnetic focusing arrangements
- H01J23/0876—Magnetic focusing arrangements with arrangements improving the linearity and homogeniety of the axial field, e.g. field straightener
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
- H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
- H01J25/10—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator
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Abstract
The invention belongs to the field of masers, and particularly relates to a fast-adjusting relativistic backward wave tube working in a local non-uniform magnetic field. The beam-wave conversion efficiency of the electron beam can be improved while the electron beam collecting position and the extracting cavity are ensured to have a certain distance. The structure of the return wave tube mainly comprises a return wave tube body, an annular cathode, a first pre-modulation cavity, a second pre-modulation cavity, a resonant reflector, a first-section slow-wave structure, a modulation cavity, a second-section slow-wave structure, an extraction cavity, a coaxial collector, an electron beam and a magnetic field coil; the magnetic field coil comprises a first coil and a second coil, and a soft magnetic material ring is arranged between the first coil and the second coil; the first coil, the second coil and the soft magnetic material ring act together to generate a local non-uniform magnetic field.
Description
Technical Field
The invention belongs to the field of masers, and particularly relates to a fast-adjusting relativistic backward wave tube working in a local non-uniform magnetic field.
Background
The relativistic backward wave tube is one of the most potential HPM (high power microwave) -devices at present, has the characteristics of high microwave power output and conversion efficiency, stability, reliability, suitability for repeated frequency pulse work and the like, and is the key point of research on domestic and foreign HPM devices.
In 2009, a fast-tuning relativistic backward wave tube combining transit radiation and cerenkov radiation was proposed, which is described in detail in the literature "Efficiency enhancement of a high power microwave generator based on ambient radiation back ward wave oscillator with a responsive reflector [ J ], renzhen xiao, Changhua Chen, Xiaowei Zhang, and Jun Sun, Journal of Applied Physics,105,053306,2009, and has higher beam-wave conversion Efficiency and output power, which has been developed in the long-foot recent years.
The structure of the conventional fast-modulation relativistic backward wave tube is shown in fig. 1, and comprises a backward wave tube body 11, an annular cathode 1, a first pre-modulation cavity 2, a second pre-modulation cavity 3, a resonant reflector 4, a first slow wave structure 5, a modulation cavity 6, a second slow wave structure 7, an extraction cavity 8, a coaxial collector 9, an electron beam 10 and a magnetic field coil 12.
The annular cathode 1 is positioned at the front part of a tube body 11 of the backward wave tube and emits annular relativistic electron beams 10 into the tube under the action of high-voltage pulses; a first premodulation cavity 2, a second premodulation cavity 3, a resonant reflector 4, a first slow wave structure 5, a modulation cavity 6, a second slow wave structure 7, an extraction cavity 8 and a coaxial collector 9 are arranged in the tube body in sequence and are at a certain distance from the annular cathode 1; the field coil 12 is installed on the periphery of the return wave tube body 11.
When the device works, the annular cathode 1 emits an annular relativistic electron beam 10 into the tube under the action of high-voltage pulses, and the electron beam 10 is subjected to certain premodulation through the first premodulation cavity 2 and the second premodulation cavity 3 under the guidance of an approximately uniform magnetic field generated by the magnetic field coil 12; the electromagnetic wave is subjected to preliminary interaction with the electromagnetic wave through the resonant reflector 4 and the first-stage slow-wave structure 5, and the modulation is further deepened; then, the electron beam 10 passes through the modulation cavity 6, the clustering effect is not affected, but the speed dispersion of the electron beam 10 is reduced, which is beneficial to the interaction of the electron beam and the electromagnetic wave in the subsequent structure; next, the electron beam 10 enters the second slow-wave structure 7 and the extraction cavity 8, the energy of the electron beam 10 is converted into microwave energy, and the acted electron beam 10 is absorbed by the coaxial collector 9 after being slightly expanded. And part of generated microwaves are transmitted to the end of the annular cathode 1, are reflected by the resonant reflector 4, the second pre-modulation cavity 3 and the first pre-modulation cavity 2, and are output after passing through the first-stage slow wave structure 5, the modulation cavity 6, the second-stage slow wave structure 7 and the extraction cavity 8 again.
By using the backward wave tube, the microwave power of 3.6GW can be generated when the voltage of a diode is 740kV and the current is 8.8kA, the microwave frequency is 4.22GHz, and the beam conversion efficiency is 55%. The magnetic field generated by the field coil is approximately uniformly distributed as shown in fig. 2, and can be described by the following function:
wherein B is magnetic induction, zaAnd zbIs an axial position constant. In particular, B ═ 2.3T, za＝2.0cm,zb＝56.7cm。
The beam-wave conversion efficiency can be increased if the position where the electron beam 10 is collected is moved toward the extraction chamber 8, but this causes the plasma generated by the collector to rapidly diffuse throughout the extraction chamber, causing severe power reduction and pulse shortening. Therefore, it is generally required in experiments that the electron beam collecting position is spaced more than 1.5cm from the extraction chamber, but this limits further improvement of the beam-wave conversion efficiency in experiments.
Disclosure of Invention
The invention aims to provide a fast-adjusting relativistic backward wave tube working in a local non-uniform magnetic field, which can ensure that a certain distance exists between an electron beam collecting position and an extraction cavity and can improve the beam-wave conversion efficiency.
In order to achieve the purpose, the fast-modulation relativistic backward wave tube with local inhomogeneous magnetic field work comprises a backward wave tube body, an annular cathode, a first premodulation cavity, a second premodulation cavity, a resonant reflector, a first slow wave structure, a modulation cavity, a second slow wave structure, an extraction cavity, a coaxial collector, an electron beam and a magnetic field coil; the annular cathode is positioned at the front part of the body of the backward wave tube and emits annular relativistic electron beams into the tube under the action of high-voltage pulses; the first pre-modulation cavity, the second pre-modulation cavity, the resonant reflector, the first slow wave structure, the modulation cavity, the second slow wave structure, the extraction cavity and the coaxial collector are sequentially arranged in the tube body of the backward wave tube;
the improvement is as follows:
the magnetic field coil is combined and comprises a first coil and a second coil, a gap L is formed between the first coil and the second coil, and the first coil and the second coil are both positioned on the periphery of the tube body of the backward wave tube; a soft magnetic material ring with the width of L1 is arranged between the first coil and the second coil; the first coil, the second coil and the soft magnetic material ring act together to generate a local non-uniform magnetic field; under the action of a local non-uniform magnetic field, an electron beam forms an expansion section between the rear section of the second-section slow-wave structure and the front section of the extraction cavity, and starts to shrink downwards at the rear section of the extraction cavity to form a contraction section, and the contraction section is finally collected by a coaxial collector; wherein, the soft magnetic material ring is made of ferrite, and the purity of iron is more than 99.8 percent.
L1< L < expansion section axial length + contraction section axial length, preferably: the value range of L is 0.5cm < L <5cm, and the value range of L1 is 0.2cm < L1< L.
Further, the local inhomogeneous magnetic field is described by the following combination function:
in the formula B1,za1,zb1Is the magnetic induction and axial position constant of the first coil, B2,za2,zb2The magnetic induction and the axial position constant of the second coil.
Preferably:
B1＝2.3T,za1＝1.05cm,zb1＝50.2cm,B2＝2.3T,za2＝1.2cm,zb2＝51.1cm。
the invention has the beneficial effects that:
1. the invention adopts two coils with gaps to form a magnetic field coil, and combines a soft magnetic material ring to generate a local non-uniform magnetic field, the electron beam starts to expand upwards at the rear section of the second-section slow-wave structure, and the radius of the electron beam is expanded to the maximum position at the extraction cavity, so that the kinetic energy of the electron beam for energy exchange is increased, and the electron beam interacts with a continuously enhanced axial electric field in the process of increasing the radius, so that higher output microwave power can be generated.
2. The invention adopts two coils with gaps to form a magnetic field coil, and combines a soft magnetic material ring to generate a local non-uniform magnetic field, the electron beam starts to shrink downwards at the rear section of the extraction cavity and is collected in the coaxial collector, the magnetic field at the electron beam collection position is more uniform, the electron collection area is increased, the energy deposition density on the collector is reduced, and the generation of plasma of the collector is favorably weakened.
Drawings
FIG. 1 is a schematic diagram of a prior art fast-tuning relativistic backward wave structure;
FIG. 2 illustrates the magnetic induction distribution used in the prior art;
FIG. 3 is a schematic diagram of a fast-tuning relativistic backward wave tube structure of the local inhomogeneous magnetic field operation of the present invention;
FIG. 4 illustrates the magnetic induction density distribution employed in the present invention;
FIG. 5 compares the power distribution of the electron beam of the present invention with that of the prior art;
FIG. 6 is a graph of axial electric field distribution at different radii for the present invention;
figure 7 comparison of the output microwave power of the present invention with that of the prior art.
The reference numbers are as follows:
the device comprises a 1-annular cathode, a 2-first pre-modulation cavity, a 3-second pre-modulation cavity, a 4-resonant reflector, a 5-first-section slow wave structure, a 6-modulation cavity, a 7-second-section slow wave structure, an 8-extraction cavity, a 9-coaxial collector, a 10-electron beam, a 101-expansion section, a 102-contraction section, an 11-backward wave tube body, a 12-magnetic field coil, a 121-first coil, a 122-second coil and a 123-soft magnetic material ring.
Detailed Description
The fast-tuning relativistic backward wave tube working in the local inhomogeneous magnetic field of the present invention is described in detail with reference to the accompanying drawings and embodiments.
Fig. 3 shows a schematic diagram of an embodiment of the present invention. The device comprises an annular cathode 1, a first pre-modulation cavity 2, a second pre-modulation cavity 3, a resonant reflector 4, a first slow wave structure 5, a modulation cavity 6, a second slow wave structure 7, an extraction cavity 8, a coaxial collector 9, an electron beam 10 and a magnetic field coil 12.
The magnetic field coil is combined, and includes a first coil 121 and a second coil 122, which have a gap L therebetween and are both located on the periphery of the return wave tube body 11; a soft magnetic material ring 123 with a width of L1 is arranged between the first coil 121 and the second coil 122 (the soft magnetic material ring can be made of ferrite, and is most commonly made of electrical pure iron, and the purity of iron is more than 99.8%); the first coil 121, the second coil 122 and the soft magnetic material ring 123 are used together to generate a local non-uniform magnetic field; under the action of a local non-uniform magnetic field, an electron beam 10 forms an expansion section 101 between the rear section of the second-stage slow-wave structure 7 and the front section of the extraction cavity 8, and starts to shrink downwards at the rear section of the extraction cavity 8 to form a contraction section 102, and the contraction section is finally collected by the coaxial collector 9;
l1< L < the axial length of the expanding section 101 + the axial length of the contracting section 102. Wherein, the value range of L is 0.5cm < L <5cm, and the value range of L1 is 0.2cm < L1< L.
The local inhomogeneous magnetic field is described by the following combination functions:
in the formula B1,za1,zb1Is the magnetic induction and axial position constant of the first coil, B2,za2,zb2The magnetic induction and the axial position constant of the second coil.
In operation, the electron beam 10 is guided by the magnetic field (fig. 4) generated by the field coil 12, passing through the first pre-modulation cavity 2 and the second pre-modulation cavity 3, and the electron beam 10 obtains a certain pre-modulation. The electromagnetic wave passes through the resonant reflector 4 and the first-stage slow-wave structure 5, and primary interaction is generated between the electromagnetic wave and the resonant reflector, so that modulation is further deepened. The electron beam 10 then passes through the modulation cavity 6, the velocity dispersion decreases, enters the second slow wave structure 7, and the beam radius expands upwards as it approaches the extraction cavity 8, reaching a maximum in the middle of the extraction cavity 8. The expansion of the beam radius causes the beam potential to decrease and thus the kinetic energy that can be converted into microwave energy to increase (fig. 5). At the same time, the electron beam interacts with a stronger axial electric field during expansion (fig. 6), thus generating higher microwave power (fig. 7). The electron beam starts to shrink downwards at the rear section of the extraction cavity and is collected in the coaxial collector, the magnetic field at the collecting position is more uniform, and therefore the collecting area of the electron beam is increased, and the energy deposition density of the collector is reduced.
In a specific example of the above embodiment, when the diode voltage is 740kV and the current is 8.8kA, the combined magnetic field parameters are:
B1＝2.3T,za1＝1.05cm,zb1＝50.2cm,B2＝2.3T,za2＝1.2cm,zb2when the wave length is 51.1cm, the microwave power is generated to be 4.2GW, the frequency is 4.22GHz, and the beam conversion efficiency is 65%. Compared with the prior art, the beam conversion efficiency is improved by 10%, and the collector energy deposition density is reduced by 40%.
Claims (4)
1. A fast-modulation relativistic backward wave tube with local inhomogeneous magnetic field work comprises a backward wave tube body, an annular cathode, a first pre-modulation cavity, a second pre-modulation cavity, a resonant reflector, a first slow wave structure, a modulation cavity, a second slow wave structure, an extraction cavity, a coaxial collector, an electron beam and a magnetic field coil; the annular cathode is positioned at the front part of the body of the backward wave tube and emits annular relativistic electron beams into the tube under the action of high-voltage pulses; the first pre-modulation cavity, the second pre-modulation cavity, the resonant reflector, the first slow wave structure, the modulation cavity, the second slow wave structure, the extraction cavity and the coaxial collector are sequentially arranged in the tube body of the backward wave tube;
it is characterized in that:
the magnetic field coil is combined and comprises a first coil and a second coil, a gap L is formed between the first coil and the second coil, and the first coil and the second coil are both positioned on the periphery of the tube body of the backward wave tube; a soft magnetic material ring with the width of L1 is arranged between the first coil and the second coil; the first coil, the second coil and the soft magnetic material ring act together to generate a local non-uniform magnetic field; under the action of a local non-uniform magnetic field, an electron beam forms an expansion section between the rear section of the second-section slow-wave structure and the front section of the extraction cavity, and starts to shrink downwards at the rear section of the extraction cavity to form a contraction section, and the contraction section is finally collected by a coaxial collector;
wherein L is more than L1 and less than the axial length of the expansion section and the axial length of the contraction section; wherein the value range of L is 0.5cm < L <5cm, and the value range of L1 is 0.2cm < L1< L.
2. The fast-tuning relativistic backward wave tube of local inhomogeneous magnetic field operation according to claim 1, characterized by:
the local inhomogeneous magnetic field is described by the following combination functions:
in the formula B1Is the magnetic induction of the first coil, za1,zb1Is the axial position constant of the first coil, B2Is the magnetic induction of the second coil, za2,zb2Is the axial position constant of the second coil.
3. The fast-tuning relativistic backward wave tube of local inhomogeneous magnetic field operation according to claim 2, characterized by:
the soft magnetic material ring is made of ferrite, and the purity of iron is more than 99.8%.
4. A fast-tuning relativistic backward wave tube working with a local inhomogeneous magnetic field according to claim 3, characterized in that:
B1＝2.3T,za1＝1.05cm,zb1＝50.2cm,B2＝2.3T,za2＝1.2cm,zb2＝51.1cm。
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| CN110718426B (en) * | 2019-09-27 | 2021-10-26 | 中国工程物理研究院应用电子学研究所 | High-frequency high-power microwave device |
| CN111048375B (en) * | 2019-12-05 | 2022-07-12 | 西北核技术研究院 | High-efficiency low-magnetic-field dual-mode working relativity backward wave tube |
| CN111584330B (en) * | 2020-05-21 | 2023-05-23 | 中国人民解放军国防科技大学 | Cerenkov microwave generator with frequency converted in C, X wave band |
| CN111799141B (en) * | 2020-07-15 | 2022-11-04 | 西北核技术研究所 | Beam bunching enhanced low-magnetic-field relativistic backward wave tube |
| CN112769024B (en) * | 2021-01-27 | 2021-11-19 | 中国人民解放军国防科技大学 | C-band relativistic Cerenkov oscillator with coaxial collector |
| CN115064429B (en) * | 2022-06-20 | 2023-03-31 | 中国人民解放军国防科技大学 | Coaxial relativistic klystron oscillator with two-stage modulation |
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| JPS5725488Y2 (en) * | 1977-04-27 | 1982-06-02 | ||
| DE3015231A1 (en) * | 1980-04-21 | 1981-10-22 | Siemens AG, 1000 Berlin und 8000 München | HIKING FIELD TUBES WITH PERIODIC-PERMANENT-MAGNETIC FOCUSING SYSTEM |
| US9673015B2 (en) * | 2014-09-04 | 2017-06-06 | Omega-P, Inc. | Partially grounded depressed collector |
| CN105489460B (en) * | 2015-12-16 | 2017-07-11 | 中国工程物理研究院应用电子学研究所 | A kind of coaxial Relativistic backward-wave oscillator of K-band |
| CN105551915B (en) * | 2016-02-02 | 2017-07-28 | 中国科学院电子学研究所 | The Periodic magnetic focusing system and klystron of a kind of adjustable magnetic fields |
| CN108470667B (en) * | 2018-03-29 | 2020-07-10 | 中国人民解放军国防科技大学 | Light and small type permanent magnet packaged Ku waveband coaxial transit device |
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