RU2573597C1 - Electric vacuum microwave device - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: first gap of a resonator has an extended interaction space (EIS) of electrons with a microwave field, the length of which is selected based on the conditions to produce negative electronic conductivity and optimal grouping of electrons. The device uses EIS with uneven electric field and high microwave voltage amplitudes within the limits of (2.6-2.8)U₀.

EFFECT: increased efficiency compared to two- and one-resonator klystron generators with two gaps.

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Description

The invention relates to electronic equipment, in particular, klystron-type microwave resonators with two gaps, in which the electron-beam velocity and density modulation of the electron beam generated by the gun occurs in the first gap and the drift tube, and the interaction of the grouped stream with the microwave field and energy take-off second cavity gap. The proposed device is designed to generate high power in all parts of the microwave range with a sufficiently high value of efficiency, exceeding the efficiency of known dual-gap single-resonator generators by 20-25%, that is, approximately twice.

Known two-resonator and two-gap single-resonator generators operating in common or antiphase modes of oscillation [1]. In all these generators, as well as in two-cavity amplification klystrons, the efficiency does not exceed 15-20% [2]. In particular, the generator klystron “with a floating drift tube” [3], known as the in-phase oscillation mode, is taken as a prototype in which the optimal conditions for self-excitation are satisfied if the electron passage angle between the narrow cavity gaps satisfies the equality θ ₁₂ = 2π (n +0.75), where n = 0, 1, 2, ... is the number of the generation zone. In the first cavity gap, the electron flux is modulated in speed, and in the drift tube in modulation in density and arrives in the second gap, where microwave energy is taken from the electrons bunched into bunches. The efficiency of the device does not exceed 20%. The amplitude of the microwave voltage at the first narrow gap is much smaller than at the second.

To obtain the optimal ratio of the amplitudes of the stresses on the cavity gaps, the capacitance of the first gap is increased due to a change in its geometry, which is a disadvantage, since the characteristic resistance and intrinsic Q factor of the resonator are reduced, which leads to a decrease in the equivalent resistance of the resonator. As a result, the contour and overall efficiency of the device are reduced. Another disadvantage of the device is the loss of power of microwave oscillations in the resonator for high-speed modulation of the electron beam in the first gap.

The aim of the invention is to increase the efficiency of single-resonator generators with two gaps in the interaction of the in-phase mode of oscillation. The proposed electronic device, like the prototype, contains an electron gun, a double-gap resonator, a drift tube, a collector, and energy output. The main difference between the proposed device and the prototype is that the length of the first gap, which should be called the extended interaction space, is selected from the condition for obtaining negative electronic conductivity in it (monotron effect). Thus, when performing the function of modulating the electron beam in terms of speed and density, power is simultaneously taken from the electron beam in the microwave field in this space, which ultimately increases the electronic and overall efficiency of the device. For effective grouping of electrons, the value of the angle of flight θ ₁ in the first gap is chosen to be greater than the optimum from the point of view of obtaining the maximum electron efficiency for the monotron:

where d ₁ is the length of the interaction space of the first gap;

, ω - круговая частота, ν₀=5,95·10⁷

- скорость электронов на входе в пространство взаимодействия первого зазора, см/с, U₀ - ускоряющее напряжение, B, λ - рабочая длина волны, см.

, ω is the circular frequency, ν ₀ = 5.95 · 10 ⁷

is the speed of the electrons at the entrance to the interaction space of the first gap, cm / s, U ₀ is the accelerating voltage, B, λ is the working wavelength, see

An effective grouping of electrons, which begins in the first gap and continues in the drift tube, is ensured with a relative amplitude of the microwave voltage at the gap ξ ₁ = U _m1 / U ₀ ranging from 2.6 to 2.8 at a distance from the first gap at which The optimal conditions for energy extraction from the grouped electron beam in the second cavity gap are observed. Since the span angle θ _{1 is} greater than 2π, these conditions turn out to be the same as for a traditional single-cavity generator with narrow gaps in the π-mode of oscillation, i.e., the span angle between the centers of the gaps should be θ ₁₂ = 2π (n + 0.25 )

не превышает величину, равную 1,25. Для получения указанных значений амплитуд СВЧ напряжения на зазорах резонатора требуется ток, величина которого выбирается из условия:The relative amplitude of the microwave voltage at the second gap

does not exceed a value equal to 1.25. To obtain the indicated amplitudes of the microwave voltage at the gaps of the resonator, a current is required, the value of which is selected from the condition:

where ρ is the characteristic resistance, Q _H is the loaded Q factor of the resonator. Such a current can be obtained in a single-beam electron-optical system, however, a generator with a multi-beam EOS will have the best parameters, which will ensure a given power with a lower accelerating voltage and a larger loop and overall efficiency.

Unlike a conventional generator with one two-gap resonator in the in-phase mode of oscillation, in which the amplitude U _{m1 is} less than the amplitude U _m2 , in the proposed device the amplitude U _m1 is 2.2-2.4 times greater than the amplitude U _m2 . To obtain such a mode of operation of the generator, in contrast to the prototype, it is proposed in the area of the second gap to make a projection of the span tube into the cavity above its end wall. The size of the protrusion Η is chosen equal to (0.04-0.06) λ. The advantage of this method of obtaining the necessary ratio of amplitudes at the gaps of the resonator is to increase the equivalent inductance in the region of the second gap and, therefore, increase the characteristic resistance of the resonator. In this case, the microwave electric field in the first gap is nonuniform, increasing in the direction of electron motion.

Numerical calculations show that when using such an extended grouper in combination with large amplitudes of the microwave voltage and an inhomogeneous electric field in the interaction space, it is possible to obtain the relative amplitude of the first harmonic of the convection current at the level of I _m1 / I ₀ = 1.4-1.55. Accordingly, the efficiency of the proposed device is increased by 15-20% compared with traditional two-gap single-cavity and two-cavity klystrons. An additional increase in efficiency is obtained by screening up to 5% power input P ₀ = I ₀ U ₀ in the first interaction space.

The technical result of the present invention is to create a new type of dual-gap single-resonator microwave generators with large span angles in the cavity interaction space, differing by a large 20-25% efficiency value compared to traditional single-cavity klystron generators.

A sketch of the proposed dual-gap single-resonator generator with an extended first interaction space is shown in FIG. 1, where it is indicated: 1 - a multipath electron gun, 2 - the first span tube, 3 - a dual-gap resonator, 4 - drift tube (second span pipe), 5 - third span pipe, 6 - rods supporting the drift pipe, 7 - energy output , 8 - collector. In the device, the span tubes have span channels located in several rows on concentric circles, and the axis of the span channels coincide with the axes of the corresponding cathodes of the multipath gun.

The principle of operation of the device is as follows. The electron gun 1 creates a multipath electron stream, which through the passage pipe 2 enters the first interaction space of the resonator 3, the length of which is determined from the condition:

. Относительная амплитуда первой гармоники конвекционного тока I_m1/I₀ после прохождения трубы дрейфа, то есть на входе во второй зазор, может достигать величины от 1,4 до 1,55.where d ₁ is the distance from the end face of the first span pipe, coinciding with the end inner wall of the resonator from the gun side, to the end of the drift pipe. In this interaction space, the electron beam is modulated in speed, preliminary grouping of electrons and the formation of an alternating convection current occur. The choice of size d ₁ within the specified limits provides negative electron conductivity. As a result, in this space the microwave power is not expended on modulation, but up to 5% of the input power is taken from the electron beam. When reducing the size d ₁ to less than 2,4π / γ grouping of electrons becomes less effective, resulting in reduced efficiency of the device. With an increase in d ₁ greater than 2.7π / γ, the active electronic conductivity becomes positive, which leads to the selection of microwave power by the electron beam and a decrease in efficiency. With the indicated length of the interaction space d _{1, the} effective grouping of electrons at a distance corresponding to the optimal condition for the selection of energy from the grouped electron flux in the second cavity gap is ensured at a relative amplitude of the microwave voltage

. The relative amplitude of the first harmonic of the convection current I _m1 / I ₀ after the passage of the drift pipe, that is, at the entrance to the second gap, can reach values from 1.4 to 1.55.

The length of the second cavity gap is selected, as in a narrow-band klystron, from the condition for obtaining the maximum efficiency of the device, equal to:

D ₂ = (0.3-0.4) π / γ,

₂ where d - distance between the ends of the drift tubes and the third tube in the transit cavity. Smaller d ₂ values correspond to longer wavelengths.

The third span pipe protrudes above the end wall of the resonator to obtain the optimal in terms of efficiency ratio of microwave amplitudes at the gaps U _m1 / U _m2 = 2.2-2.4. The distance from the end face of the third span pipe to the end wall of the resonator and the diameter of the span pipes are selected from the conditions:

where H is the distance from the end face of the third passage pipe to the end wall of the resonator from the collector side, D is the diameter of the passage pipes.

The choice of size D within the specified limits allows you to place in the span pipes the required number of span channels with electron beams and, accordingly, provide the current necessary for the effective operation of the device. Smaller values of the coefficients when choosing the size D and larger values when choosing the size Η correspond to longer wavelengths.

Examples of dependences of the ratio of the amplitudes of the stresses at the gaps U _m1 / U _m2 and the characteristic resonator resistance ρ on the relative protrusion size of the third span pipe H / λ are shown in FIG. 2 and FIG. 3.

The length of the drift pipe is selected from the condition of obtaining the maximum value of I _m1 / I ₀ at the entrance to the second cavity gap while fulfilling the optimal phase conditions for the generator self-excitation during operation in the first generation zone (n = 1):

where L is the distance between the ends of the drift pipe. The drift pipe is supported by rods 6. The outer shell of the resonator can be made of shorted segments of a rectangular or circular waveguides.

Numerical calculations show the possibility of obtaining an electronic efficiency equal to 56% at a frequency of 2.45 GHz in a two-gap single-resonator generator with an accelerating voltage of 19 kV, and a total perveance of an electron flux of 15 rays of 4.5 μA / V ^3/2 .

Thus, when using the proposed technical solutions, the following result can be achieved: in double-gap single-resonator generators with an extended first interaction space, which ensures negative electronic conductivity, the efficiency increases by 20–25%, i.e., more than twice, compared to known single-resonator klystron generators. The simplicity of the design, combined with high values of efficiency makes it promising to use the proposed device as a source of high power.

Information sources

1. Shevchik V.N. Fundamentals of ultra high frequency electronics. - M .: Owls. Radio, 1959.- S. 173.

2. Berezin V.M., Buryak V.S. Microwave electronic devices. - M.: Higher School, 1985.- S. 48.

3. Chodorow Μ., Fan S. A floating drift-tube klystron // Proc. IRE. - 1953. - P. 25.

Claims (2)

1. Microwave vacuum device containing an electron gun, drift tubes through which an electron beam is passed, an active two-gap resonator excited in common mode of oscillation, a drift tube between gaps, an energy output and a collector, characterized in that the length of the first interaction space (gap) resonator - the distance between the end face of the first span pipe installed in the end face of the resonator from the side of the gun and the end of the drift pipe - is selected from the condition of obtaining the negative active component of the electron pr conduction (monotron effect):
d ₁ = (2.4-2.7) π / γ,
where d ₁ is the distance between the ends of the pipes forming the first gap, cm,

, 1 / cm, ω is the circular oscillation frequency, υ ₀ is the speed of the electrons at the entrance to the resonator interaction space, cm / s, λ is the working wavelength, cm, U ₀ is the accelerating voltage, V, and the current value of the electron beam is I ₀ choose from the condition:
I ₀ = (6-8) U ₀ / ρQ _n,
where ρ is the characteristic resistance, Q _n is the Q factor of the loaded resonator, the electron gun being multipath, the passage channels are made in the span tubes located coaxially with the corresponding cathodes of the electron gun, and the end surface of the first span pipe coincides with the plane of the inner surface of the end wall of the resonator located from the side of the electron gun, and the length of the second gap between the ends of the drift pipe and the third span pipe is determined from the condition:
d ₂ = (0.3-0.4) π / γ,
the length of the drift pipe, which determines the distance between the gaps, is chosen from the condition:
L = (0.75-1) π / γ,
where L is the distance between the ends of the drift pipe, and the distance from the end of the third span pipe to the end of the resonator from the collector side and the diameter of the span pipes is chosen from the conditions:
H = (0.04-0.06) λ,
D = (0.2-0.5) λ,
where H is the distance from the end face of the third span pipe to the end wall of the resonator from the collector side, D is the diameter of the span pipes, and lower values of the coefficients when choosing the size D and larger values when choosing the size H correspond to large wavelengths. 2. Microwave vacuum device according to claim 1, characterized in that the resonator is made in the form of a segment shorted at the ends of a rectangular or circular waveguide.

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