RU2747579C2 - Powerful broadband klystron - Google Patents

Abstract

FIELD: microwaves.

SUBSTANCE: invention relates to the field of microwave electric vacuum devices of klystron type, in particular to continuous broadband klystrons with a continuous output power level of over 25 kW, which can be used as power amplifiers in radio transmitters of long-range space communication systems. The powerful broadband klystron contains the main amplifier klystron, which includes the structural elements of the electron-optical system (EOS) mounted on one main axis, the cathode, the focusing electrode, the anode, the span pipes of the input, intermediate and output active resonators, and the collector. All side span pipes are installed in side covers that separate the active resonators and form flat surfaces of flattened elliptical cylinders (or geometric shapes close to them in shape), made in a single resonant system housing. The central axis of these cylinders is perpendicular to the main axis, and the bases of the cylinders are closed by end caps so that the interaction space between the end parts of the side span pipes in the intermediate resonators is a single high-frequency gap, and the interaction space in the input and output active resonators, each containing a central span pipe installed in the middle of a resonant plate with slits, is a double high-frequency gap. In addition, these resonators, together with the passive resonators in the input and output circuits, form bandpass filter systems. The klystron contains an additional amplifier klystron, the structural elements of which repeat in shape and composition the structural elements of the main klystron and are located on an additional axis that is parallel to the main axis. In each of the active single-gap intermediate resonators, at an equal distance between the main and additional span pipes, the first central rod is installed parallel to the additional axis, electrically connecting the side covers to each other, and in each of the active two-gap resonators, made with possibility of exciting an inphase (2π) oscillation mode, a second central rod is inserted perpendicular to the additional axis, symmetrically closing on the end caps one end of the resonant plate of the main klystron with the end of the additional resonant plate of the additional klystron adjacent to it. The other two ends of the resonant plates remain electrically closed to the resonator body.

EFFECT: improved reliability and quality of radio communication, an increased thermal stability of the resonator unit.

4 cl, 1 tbl, 7 dwg

Description

The invention relates to the field of microwave klystron type electrovacuum devices, in particular to continuous broadband klystrons with a continuous output power level of more than 25 kW, which can be used as power amplifiers in radio transmitters of long-range space communication systems.

These klystrons typically operate in the 7.145 GHz to 7.235 GHz (X-band) frequency range with a bandwidth of at least 90 MHz.

When operating in the short-wave part of the microwave range, liquid cooling is used to ensure the specified thermal modes of operation of the device. Therefore, such devices usually use single-gap resonators in the form of oval cylinders, which are performed by milling in the common block of the resonance system, which has channels for passing the coolant [1]. The advantages of such resonators are determined by the positive properties of the H ₁₀ wave, including: stability of the plane of polarization; absence of higher types of waves in a wide frequency range; independence of the critical frequency from one of the dimensions (waveguide height); low attenuation due to insignificant losses in the walls of the waveguide.

The implementation of future space flights in deep space requires an increase in the reliability and quality of radio equipment of terrestrial radio communication systems. This can be done by increasing the output power level of the klystron amplifiers from 12 kW to 25 kW [2]

The known design of a klystron of an average power level, which has in a common vacuum shell two partial multibeam klystrons (MLK) with two-gap resonators excited in the antiphase mode of oscillations [3]. Both the input and output resonators of the partial MLTs are connected in pairs, forming, respectively, the input and output resonance systems. In this case, intermediate resonators (single-tube resonators) of partial MLTs are not connected with neighboring resonators. It is possible to provide an average level of output power in such a device either by further increasing the number of beams, or by increasing the accelerating voltage. However, in the first case, this leads to a large irregularity in the distribution of the HF electric field in the channels of the span pipes and, accordingly, to a decrease in the efficiency and the level of output power. In the second case, serious problems arise associated with heat removal from the middle bridges of the double-gap resonators, which, when operating on the π form of oscillations, have small dimensions. Therefore, the MLK provides stable operation at high levels of output power only in a pulsed mode of operation (output power is about 15 kW in a 500 MHz band with a device efficiency of 15%) [4].

Another way to increase continuous power output is through multi-barreled klystrons (MSCs).

MSC is constructively a single device that combines two (or more) partial klystrons in a common vacuum-tight shell [3].

The input and output resonators of each partial klystron in this design are connected in pairs and, accordingly, with a single input and output of energy. Due to a more uniform distribution of thermal loads, which are distributed over the current-collecting surfaces of partial klystrons (shafts) and separate receiving cavities of the collector, the MSC is able to withstand significantly higher thermal loads than a single klystron equivalent in terms of output power.

However, in such a device, intermediate resonators do not have any electromagnetic connection with an adjacent channel (barrel), which greatly complicates the design of the device and its adjustment to a given level of output power and bandwidth. In addition, with an increase in the number of trunks, the characteristic impedance of the output resonant system decreases correspondingly and the band of amplified frequencies narrows. [3, 5, 6].

Known taken as a prototype, a powerful broadband klystron [7], containing structural elements mounted on one main axis: cathode, focusing electrode; anode; Span tubes of input, intermediate and output active resonators; collector; moreover, all side flight tubes are installed in side covers separating the active resonators and forming flat surfaces of flattened elliptical cylinders (or close to them in the shape of geometric figures), made in a single housing of the resonant system, and the central axis of these cylinders is perpendicular to the main axis, and the bases of the cylinders closed with end caps so that the interaction space between the end parts of the side flight tubes in the intermediate resonators is a single high-frequency gap, and the interaction space in the input and output active resonators containing each central flight tube installed in the middle of the resonance plate with slots is a double high frequency gap; in addition, these resonators, together with passive resonators in the input and output circuits, form bandpass filter systems. To ensure the specified thermal modes of operation of the device, liquid cooling is used.

This device achieves an amplified frequency band of - 1 dB on the order of 80 MHz at a continuous output power level of 10-12 kV. A further increase in the accelerating voltage required in such a device to achieve an output power of more than 25 kW requires the manufacture of complex and bulky power supplies. In addition, the maximum value of the accelerating voltage in this case will be limited by the breakdown condition in the microwave gap of the output resonator. In addition, the achievement of high power levels is impossible due to the difficulty of removing heat from the middle bridges of the double-gap resonators operating on the π-mode.

The technical problem of the invention is the need to create a powerful broadband klystron, which allows at least to double the level of continuous output power while expanding the amplified frequency band without significant deterioration of the parameters of its electrodynamic and electro-optical systems.

The technical result is to increase the reliability and quality of radio communication while maintaining the thermal stability of the resonator unit.

The problem posed is solved by the fact that in a powerful broadband klystron containing structural elements of an electron-optical system (EOS) mounted on one main axis, a cathode, a focusing electrode, an anode, span tubes of the input, intermediate and output active resonators, a collector. All side flight tubes are installed in side covers separating the active resonators and being part of the flat surfaces of flattened elliptical cylinders (or geometrical figures close to them in shape), made in a single housing of the resonant system. The central axis of these cylinders is perpendicular to the main axis, and the bases of the cylinders are closed with end caps so that the interaction space between the end parts of the lateral flight tubes in the intermediate resonators is a single high-frequency gap, and the interaction space in the input and output active resonators containing each central flight tube, installed in the middle of the resonant plate with slots, it is a double high-frequency gap; in addition, these resonators, together with passive resonators in the input and output circuits, form bandpass filter systems.

According to one of the proposed options, the design of the klystron, it is double-barreled so that the additional structural elements of the second barrel repeat in shape and composition the structural elements of the main barrel and are located on an additional axis that is parallel to the main axis. At the same time, in the active single-gap intermediate resonators, at an equal distance between the main and additional flight tubes parallel to the additional axis, the first central rod is installed, electrically connecting the side covers, and in the active double-gap resonators, which are made with the possibility of exciting the in-phase (2π) vibration modes, are introduced, perpendicular to the additional axis, the second central rod, symmetrically closing to the end caps one end of the resonant plates of the main barrel with the adjacent end of the additional resonant plate of the additional barrel, with the other two ends of the resonance plates remaining electrically closed to the resonator body.

The EOS parameters of the additional shafts repeat the parameters of the EOS of the main amplifying shaft, while the flight angles between the centers of the gaps of the input and output active double-gap resonators are selected from the condition:

,

,

– постоянная продольного распространения электронного пучка,

– круговая частота (рад/с), V ₀ – скорость электронного потока (м/с), d – длина зазора между центральной и боковой пролетной трубой (м), l – длина центральной пролетной трубы (м).Where

Is the longitudinal propagation constant of the electron beam,

Is the circular frequency (rad / s), V ₀ is the electron flow velocity (m / s), d is the length of the gap between the central and lateral flight tube (m), l is the length of the central flight tube (m).

According to one of the options, all lateral spans of a powerful broadband klystron are installed in a flat part of geometric shapes similar in shape to flattened elliptical cylinders, for example, in the form of an octahedral prism with unequal edges, the largest of which corresponds to the side cover.

According to another variant, the optimal shapes of the cross-section of the rods are proposed: a rectangular shape of the first central rod in two-gap active resonators and a round shape for the second central rod in single-gap active resonators.

These essential features distinguish the proposed solution from the prototype and determine the compliance of this solution with the "novelty" criterion.

The proposed invention makes it possible to double the level of continuous output power, providing a wide band of amplified frequencies while maintaining the parameters of the electrodynamic and electro-optical systems and the thermal stability of the resonator unit.

The invention is illustrated by drawings, where figure 1 shows a general view of the proposed device, figure 2 shows a longitudinal section of an active double-gap resonator, figure 3 shows a cross-section of an active double-gap resonator, figure 4 shows a longitudinal section of an active single-gap intermediate resonator, Fig. 5 shows a cross-section of an active single-gap intermediate resonator, Fig. 6 shows the distribution of the electric HF field in an active single-gap intermediate resonator, Fig. 7 shows the distribution of an electric HF field in an active two-gap resonator.

Positions in the drawings indicate:

1 - the main axis of the trunk,

2 - cathode,

3 - focusing electrode,

4 - anode,

5 - input active double-gap resonator,

6 - intermediate active single-gap resonator,

7 - output active double-gap resonators;

8 - collector,

9 - side spans,

10 - side covers,

11 - flattened elliptical cylinders,

12 - housing of the resonant system,

13 - the central axis of the oblate elliptical cylinders,

14 - end caps,

15 - central span pipe,

16 - resonant plate,

17 - communication gap,

18 - passive resonator,

19 - additional axis,

20 - additional spans,

21 - the first central rod,

22 - the second central rod.

A powerful broadband klystron (Fig. 1) contains a main amplifying barrel, which includes structural elements of the EOS mounted on one main axis 1, a cathode 2, a focusing electrode 3, an anode 4, the passage tubes of the input 5, intermediate 6 and output 7 active resonators, collector 8, and all side flight tubes 9 are installed in side covers 10, separating active resonators and forming flat surfaces of flattened elliptical cylinders (or close to them in the shape of geometric figures) 11, made in a single housing of the resonance system 12, the central axis of these cylinders 13 is perpendicular to the main axis, and the bases of the cylinders are closed with end caps 14 so that the interaction space between the end parts of the lateral flight tubes in the intermediate resonators is a single high-frequency gap, and the interaction space in the input and output active resonators containing each central flight tube 15 installed in middle e resonant plate 16 with slots 17 is a double high-frequency gap; in addition, these resonators, together with passive resonators 18 in the input and output circuits, form bandpass filter systems. Additional structural elements of the second shaft repeat in shape and composition, structural elements of the main shaft (2-9, 10, 15, 17) and are located on an additional axis 19, which is parallel to the main axis; moreover, in the active single-gap intermediate resonators at an equal distance between the main and additional flight tubes 20 parallel to the additional axis, the first central rod 21 is installed, electrically connecting the side covers; and in active double-gap resonators, which are made with the possibility of exciting in-phase (2π) vibration modes, a second central rod 22 is introduced, perpendicular to the additional axis, symmetrically closing one end of the resonance plate of the main barrel with the adjacent end of the additional resonance plate of the additional barrel to the end caps ; wherein the other two ends of the resonance plates remain electrically closed to the resonator body.

, где

– постоянная продольного распространения электронного пучка,

– круговая частота (рад/с), V ₀ – скорость электронного потока (м/с), d – длина зазора между центральной и боковой пролетной трубой (м), l – длина центральной пролетной трубы (м)) то происходит эффективная модуляция электронов по скорости, которая в пролетной трубе входного 5 активного двухзазорного резонатора переходит в модуляцию по плотности. При дальнейшем движении электронных потоков через активные однозазорные промежуточные резонаторы 7 процессы группировки усиливаются, достигая максимума конвекционного тока первой гармоники в двойном зазоре выходного активного двухзазорного резонатора 8. В результате чего в выходную электродинамическую систему, содержащую выходной активный двухзазорный резонатор 7, поступают сгруппированные сгустки электронов, которые отдают ему свою энергию в тормозящие полупериоды СВЧ поля в двух ВЧ зазорах с синфазными напряжениями одновременно от двух стволов. Затем эта энергия передается по электромагнитной связи в пассивный резонатор 18 через выходной прямоугольный волновод и через вывод энергии уходит в нагрузку. После прохождения выходного активного двухзазорного резонатора электроны осаждаются одновременно на двух коллекторах 8, имеющих каждый систему принудительного водяного охлаждения.The device works as follows. Two electron beams in each of the barrels are emitted by electron guns, each of which consists of a cathode 2, a focusing electrode 3. Under the action of the accelerating potential of anode 4, electron beams enter the double gap of the input 5 active double-gap resonator, which together with passive resonators 18 in the input circuit forms a band-pass filter system excited by an input signal entering the filter system from the energy input side. Since the angles of flight between the centers of the gaps of the input active double-gap resonator are chosen from the condition of optimal interaction in the in-phase mode of oscillations (

where

Is the longitudinal propagation constant of the electron beam,

Is the circular frequency (rad / s), V ₀ is the electron flow velocity (m / s), d is the length of the gap between the central and lateral flight tube (m), l is the length of the central flight tube (m)) then effective modulation of electrons occurs by speed, which in the passage tube of the input 5 active double-gap resonator turns into density modulation. With the further movement of electron flows through the active single-gap intermediate resonators 7, the bunching processes increase, reaching a maximum of the convection current of the first harmonic in the double gap of the output active double-gap resonator 8. As a result, bunched electron bunches enter the output electrodynamic system containing the output active double-gap resonator 7, which give it their energy in the braking half-periods of the microwave field in two high-frequency gaps with common-mode voltages from two barrels simultaneously. Then this energy is transmitted via electromagnetic coupling to the passive resonator 18 through the output rectangular waveguide and through the energy output goes into the load. After passing through the output active double-gap resonator, electrons are deposited simultaneously on two collectors 8, each having a forced water cooling system.

Numerical 3D modeling of klystron resonators showed that in the proposed double-barreled klystron, despite a drop in the effective characteristic resistance of 11% compared to the prototype, it is possible to provide a small inhomogeneity of the HF electric field in the gaps (both in the double-gap resonator - 2.7%, and in the single-gap resonator - 0.5 %), which made it possible to increase the electronic efficiency by 15% and increase the output power by 2.4 times.

Due to the operation of the output resonator in the in-phase mode of oscillations and the use of a resonant plate with the preservation of the shape of the slots, in which the width of the plates increases as they approach the short-circuit point, as well as the presence of holes for water cooling in the resonator housing, the thermal stability of the output active double-gap resonator is maintained at increased (more than 2 times) level of output power.

Evaluation of the amplified frequency band at the level of –3 dB, carried out according to the formula known from the klystron theory, showed that in the new design of the device it is possible to increase the bandwidth of the amplified frequencies by 1.8 times:

– относительная величина конвекционного тока;

– эффективное характеристическое сопротивление электронного потока, Ом;

– микропервеанс одного луча, мкА/В^3/2; N – количество стволов; U ₀ – ускоряющее напряжение, В;

– рабочая частота, МГц.Where

- the relative value of the convection current;

- effective characteristic impedance of the electron flow, Ohm;

- micropervance of one beam, μA / V ^3/2 ; N is the number of trunks; U ₀ - accelerating voltage, V;

- operating frequency, MHz.

Comparison of the main parameters of the prototype and the proposed invention is shown in the table.

Table. Parameters of the prototype and invention

Klystron Accelerating
voltage, kV MicroPerveance
one beam, μA / V ^3/2 Effective characteristic impedance, Ohm Day off
power, kWt Electronic
Efficiency,% Frequency band, MHz Prototype sixteen 1.24 56.8 11.6 31.6 90 Invention sixteen 1.24 50.3 27.4 37.2 159

A powerful broadband klystron can be used as power amplifiers with a level of more than 25 kW in radio transmitters of distant space communication systems, providing an increase in the reliability and quality of radio communication while maintaining the thermal stability of the resonator unit.

The technical result is the creation of a powerful broadband klystron, which allows at least to double the level of continuous output power while expanding the band of amplified frequencies by 1.8 times without significant deterioration of the parameters of its electrodynamic and electro-optical systems.

The present invention was created within the framework of a grant for the competition "UMNIK-17", contract number 12717GU / 2017 dated 04/25/2018.

List of sources

1. Katsman, Yu.A. Microwave devices. Theory, foundations of calculation and design of electronic devices: Textbook for universities. T.2. / Yu.A. Katsman // M .: Higher school, 1973 .-- 382 p.

2. Evaluation of the VA-876P Klystron for the 20-kW X-Band Uplink Transmitter: DSN progress Report: 42-54 / Jet Propulsion Laboratory: Radio Frequency and Microwave Subsystem Section, perf. Kolbly R. B. - 10 P. - References: P.42

3. Tuv, A.A. Three-centimeter powerful broadband low-voltage multi-beam amplifying klystron double-barreled design / A.A. Tuv // Radio engineering. - 2000 - No. 2. - S.51-53.

4. Pugnin, V.I. Estimation of the limiting power of multibeam klystrons with resonators on the main mode of oscillations for modern radars / V.I. Pugnin // Radio engineering. - 2000 - No. 2. - S.43-50.

5. Touv, A.A. X-Band high power broadband low-voltage multi-beam klystron amplifier with two-barrel design / A.A. Touv // Proceedings of the International University Conference "Electronics and Radiophysics of Ultra-High Frequencies". - St. Petersburg, May 1999. - P. 83-85.

6. Pat. No. 2244980 RF, MPK6 H 01 J 25/10, H 01 J 23/18. Multi-beam O-type device / Pugnin V.I., Yunakov A.N., Burdina T.N .; applicant and patentee FSUE NPP Istok - No. 2003125466/09; declared 08/18/2003; publ. 20.01.2005, Bul. No. 2. - 10 p .: 3 ill.

7. Pat. No. 2483386 RF, MKP7 H 01 J 25/00. Powerful broadband klystron / Tsarev V.A., Shirshin V.I., Mullin V.V., Semenov V.K., Pichugin P.A .; applicant and patentee of JSC NPP Contact. - No. 2011136022/07; declared 08/29/2011; publ. 05/27/2013, Bul. 15 - 13 p .: ill.

Claims (6)

1. Powerful broadband klystron containing the main amplifying barrel, which includes structural elements of an electron-optical system (EOS) mounted on one main axis, a cathode, a focusing electrode, an anode, flight tubes of input, intermediate and output active resonators, a collector, and all lateral flight tubes are installed in side covers separating active resonators and forming flat surfaces of flattened elliptical cylinders (or close to them in the shape of geometric figures), made in a single housing of the resonance system, the central axis of these cylinders is perpendicular to the main axis, and the bases of the cylinders are closed by end covers so that the interaction space between the end parts of the lateral flight tubes in the intermediate resonators is a single high-frequency gap, and the interaction space in the input and output active resonators containing each central flight tube installed in the middle of the resonator nance plate with slots, is a double high-frequency gap; In addition, these resonators, together with passive resonators in the input and output circuits, form band-pass filter systems, characterized in that the klystron contains an additional amplifying barrel, the structural elements of which are identical in shape and composition to the structural elements of the main barrel and are located on an additional axis, which is parallel main axis; in addition, in each of the active single-gap intermediate resonators at an equal distance between the main and additional flight tubes parallel to the additional axis, a first central rod is installed, electrically connecting the side covers, and in each of the active double-gap resonators made with the possibility of exciting in-phase (2π) vibration modes, a second central rod is introduced, perpendicular to the additional axis, symmetrically closing to the end caps one end of the resonance plate of the main barrel with the adjacent end of the additional resonance plate of the additional barrel, and the other two ends of the resonance plates remain electrically closed to the resonator body. 2. Powerful broadband klystron according to claim 1, characterized in that the electrical parameters of the EOS of the additional shafts repeat the electrical parameters of the EOS of the main amplifying barrel, while the flight angles between the centers of the gaps of the input and output active double-gap resonators are selected from the condition:

, Where

Is the longitudinal propagation constant of the electron beam,

Is the circular frequency, V ₀ is the electron flow velocity, d is the length of the gap between the central and lateral flight tube, l is the length of the central flight tube. 3. Powerful broadband klystron according to claim 1, characterized in that all lateral spans are installed in a flat part of geometric shapes similar in shape to flattened elliptical cylinders, for example, having the form of an octahedral prism with unequal edges, the largest of which corresponds to the side cover. 4. Powerful broadband klystron according to claim 1, characterized in that the first central rod in the double-gap active resonators has a rectangular shape, and the second central rod in the single-gap active resonators has a circular cross-section.

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