RU2578213C1 - Method of determining value of longitudinal displacement of thermal cathode caused by heating thereof in microwave device (versions) - Google Patents

Abstract

FIELD: electronic equipment.

SUBSTANCE: invention relates to electronic engineering and can be used in making electron guns with hot cathodes for microwave devices. Method for determining value of longitudinal displacement of hot cathode (Δk) caused by heating it in a microwave device includes measuring current of gun I_izm. at zero and one or more negative with respect to cathode voltages on focusing electrode (FE) being determined from comparison Δk I_izm. with values of current gun and $${\text{I}}_{\text{Δ}\text{k}}{}_{\text{1}}$$

$${\text{I}}_{\text{Δ}\text{k}}{}_{\text{2}}$$

calculated for two different longitudinal displacements of cathode Δk₁ and Δk₂ at same voltage value on FE, in which gun current I_izm. was measured according to formula: $$\text{Δk}={\text{Δk}}_{\text{1}}+\left({\text{Δk}}_{\text{2}}-{\text{Δk}}_{\text{1}}\right)\times \frac{{\text{I}}_{\text{izm}\text{.}}-\text{IΔ}{\text{k}}_{\text{1}}}{\text{IΔ}{\text{k}}_{\text{2}}-\text{IΔ}{\text{k}}_{\text{1}}}.$$

Another embodiment includes a method of measuring current I_{0 izm.} guns at zero with respect to cathode voltage U₀ on focusing electrode (FE) and gun current I_{1 izm.} with a negative voltage U₁ on FE and comparing relative difference ΔI / I_0izm. current measured values with relative differences $${\text{ΔI/I}}_{\text{0}\Delta k\text{1}},$$

$${\text{ΔI/I}}_{\text{0}\Delta k2}$$

calculated current values where ΔI / I_0izm.= (I_0izm.-I_1izm.) / I_0izm., and

$${\text{ΔI/I}}_{\text{0}\Delta k1}=\left({\text{I}}_{\text{0}\Delta k1}-{\text{I}}_{\text{1}\Delta k1}\right)/{\text{I}}_{\text{0}\Delta k1}$$

$${\text{ΔI/I}}_{\text{0}\Delta k2}=\left({\text{I}}_{\text{0}\Delta k2}-{\text{I}}_{\text{1}\Delta k2}\right)/{\text{I}}_{\text{0}\Delta k2}$$

- relative difference between values of current gun, designed for two different displacements Δk₁ and Δk₂, and at same values of U₀, U₁ on FE and Δk based on a comparison is given by:

EFFECT: technical result is simplification of technology determine value Δk while ensuring high accuracy of said definition that allows to produce a gun and a magnetic focusing system with small fluctuations in transit channel of beam microwave devices, and thereby prevent breakdown of microwave device.

2 cl, 3 dwg

Description

The invention relates to electronic equipment and can be used in the manufacture of electronic guns with thermal cathodes for microwave devices.

It is known to determine the longitudinal displacement of the cathode (Δk) caused by its heating by the method of dial indicators of displacement [1], using a microscope [2], and the methods of holographic and speckle interferometry [3]. The measurement results obtained by the first method are not reliable enough, since the indicators are in mechanical contact with the electrodes and heat up. Measurements using a microscope are carried out through windows etched in the shells and parts of the cathode nodes. In this case, the glass of the viewing window introduces spherical aberrations and does not allow to precisely focus the image of the edge of the electrode. The glow of the cathode also interferes with accurate aiming. The method of holographic interferometry makes it possible to determine the Δk value with an error component of micrometers, and the error of the speckle interferometer method when determining the Δk value is approximately 0.3 μm. However, a drawback of the methods of holographic and speckle interferometry is the great complexity and the need to produce special models of the electron gun. Thus, determining Δk is a difficult task.

At the same time, the determination of Δk is very important, since this value can be 2-3% of the cathode diameter [4]. Such a longitudinal displacement of the cathode leads to an increase in the beam perveance by 10% or more and to an increase in the pulsations of the beam in the passage channel of the microwave vacuum device. An increase in the pulsations of the beam leads to an increase in the number of electrons deposited on the walls of the passage channel, that is, to an increase in the thermal power released on these walls, and this can lead to breakdown of the microwave device.

The technical result of the proposed method is to simplify the technology for determining the Δk value while ensuring high accuracy of this determination, which allows us to produce, taking into account the Δk value determined by the proposed method, a gun and a magnetic focusing system with small beam pulsations in the passage channel of the microwave device, i.e. allows you to reduce the number of electrons deposited on the walls of the passage channel, and thereby prevent the failure of the microwave device.

,

, рассчитанных для двух разных продольных смещений катода Δk₁, Δk₂ при том же значении напряжения на ФЭ, при котором ток пушки I_изм. был измерен:This result is achieved by measuring the cathode current at zero voltage relative to the cathode at the focusing electrode (PV) and at one or more negative values of the voltage at the PV. After that, Δk is determined by the formula below, obtained (taking into account the direct proportionality of the magnitude of the gun current to Δk) from a comparison of the measured current value I _meas. and current values

,

calculated for two different longitudinal displacements of the cathode Δk ₁ , Δk ₂ at the same voltage value on the PV, at which the gun current I _rev. was measured:

The determination of Δk by formula (1) at different voltage values on the PV makes it possible to reduce the error in determining Δk associated with the error of current measurement. Indeed, the found Δk values should be close to each other, therefore, a significant difference between Δk at voltage U _n on the PV and its values at other voltages on the PV indicates an error in measuring current at a given voltage U _n , which indicates the need to throw out the erroneous value Δk from consideration.

,

рассчитанных значений тока, где ΔI/I_0изм.=(I_0изм.-I_1изм.)/I_0изм.,

и

- относительные разности значений тока пушки, рассчитанных для двух разных продольных смещений катода Δk₁, Δk₂ и при тех же значениях напряжения U₀, U₁ на ФЭ, причем определение величины Δk на основе этого сравнения осуществляют по формуле:Another variant of the proposed method for determining Δk includes measuring current I _oism. guns at zero relative to the cathode voltage U ₀ on the focusing electrode (FE) and the gun current I 1 _ism. with a negative voltage U ₁ on the FE and comparison of the relative difference ΔI / I _{0 ISM.} measured current values with relative differences _.

,

calculated current values, where ΔI / I _{0 ISM.} = (I _0izm. -I _1izm. ) / I _0izm. ,

and

- the relative differences of the current values of the gun, calculated for two different longitudinal displacements of the cathode Δk ₁ , Δk ₂ and at the same voltage values U ₀ , U ₁ on the PV, and the determination of Δk based on this comparison is carried out according to the formula:

(дроби

) сокращаются.Using the relative difference of the measured current values allows us to avoid the influence of the error in calculating the cathode current on the accuracy of determining Δk, since the same errors in the numerator and denominator of the fraction

(fractions

) are being reduced.

In FIG. 1 and FIG. Figure 2 shows the electron trajectories and the value of the beam current obtained as a result of calculating [5] guns with a value Δk_one= 0.05 and Δk₂= 0.15 mm, respectively. In FIG. Figure 3 shows graphs of the current dependence on the voltage of the control electrode, and the measured current values are represented by crosses on curve 1, the calculated current values in the gun with Δk₂ are represented by crosses on curve 2, and in the gun with Δk_one - on curve 3. Substituting in (1) the measured and calculated current values (see Fig. 3), for example, at a zero voltage value on the PV, we find Δk = 0.05 + (0.15-0.05) × (910-793) / ( 870-793) = 0.2 mm. In accordance with a second embodiment for determining Δk, current I_0ism., I_1ism. at zero and negative (-150 V in Fig. 3) relative to the cathode, the voltage values on the PV and find the relative difference (0.169) of the measured current values (ΔI / I_0ism.) Further, for two different preset values of the longitudinal displacement of the cathode Δk_one= 0.05 mm and Δk₂= 0.15 mm calculate the currents of the gun I_0Δk1, I_0Δk2at zero voltage U₀ on PV and gun currents I_1Δk1, I_1Δk2 at voltage U_one on a PV equal to -150 V, while the relative differences between the calculated currents in this gun are 0.1931 (Δk_one= 0.05 mm) and 0.1765 (Δk₂= 0.15 mm). Substituting the relative differences of the current values in (2), we find Δk = 0.05 + (0.15-0.05) × (0.169-0.1931) / (0.1765-0.1931) = 0.195 mm. It can be seen that Δk (0.2 and 0.195 mm) determined by the first and second variants of the proposed method for determining Δk are close to each other and are in good agreement with the value of Δk measured on a specially made model of the device and equal (according to several measurements) 0.15-0.2 mm. After determining the Δk value, it is taken into account when optimizing the design of the gun, in particular, when adjusting the longitudinal distances between the gun electrodes, as well as when adjusting the location of the magnetic focusing system relative to the cathode and optimizing the matching of the electron beam with the magnetic field of the focusing system [6]. This allows focusing of the beam with small pulsations of its boundary, which reduces the number of electrons deposited on the walls of the passage channel, and thereby reduces the likelihood of the microwave device failing.

Information sources

1. The method of calculating the perveance of the electron gun / V.P. Rybachek, V.K. Fedyaev, V.I. Yurkin et al. - In the book: Quality, strength, reliability and manufacturability of EEC. - Kiev: Naukova Dumka, 1976.

2. Skaptsov A.A., Koshelev B.C. Thermal displacements in the cathode-grid node of the EEC microwave. - Electronic equipment. Ser. Microwave Electronics, 1983, no. 3 (339), p. 67-69.

3. V.P. Ryabuho, I.S. Klimenko, A.N. Yakunin. The study of thermal displacements of the electrodes of the electron gun by methods of holographic and speckle interferometry - Electronic equipment. Ser. Microwave Electronics, 1986, no. 2 (386), p. 48-52.

4. Zabirova E.G., Morev S.P., Yakunin A.N. Comprehensive analysis of thermophysical, thermomechanical, and electron-optical processes in electron guns of high-voltage electronic components. - Electronic equipment. Ser. Microwave Electronics, 1986, no. 2 (386), p. 27-30.

5. A set of programs for computer-aided design of electronic guns with grid control / A.I. Petrosyan, V.D. Zhuravleva, V.V. Penzyakov, V.I. Rogovin // Applied Physics. - 2002. - No. 3. - S. 127-133.

6. Program for calculating a multi-speed axially symmetric beam in a magnetic field / V.D. Zhuravleva, S.P. Morev, V.V. Penzyakov, V.I. Rogovin // Electronic Engineering. Ser. 1, Microwave Electronics. - 1985. - Vol. 1 .-- S. 70.

Claims (2)

1. The method of determining the magnitude of the longitudinal displacement of the thermal cathode (Δk) caused by its heating in a microwave device, including measuring the current of the gun I _rev. at zero and at one or several negative relative to the cathode voltage values on the focusing electrode (FE), and Δk is determined from a comparison of I _meas. with gun current values

and

calculated for two different longitudinal displacements of the cathode Δk ₁ and Δk ₂ at the same voltage value on the PV at which the gun current I _meas. , according to the formula:

2. A method for determining the magnitude of the longitudinal displacement of the thermal cathode (Δk) caused by its heating in a microwave device, including current measurements I _0izm. guns at zero relative to the cathode voltage U ₀ on the focusing electrode (FE) and the gun current I 1 _ism. with a negative voltage U ₁ on the FE and comparison of the relative difference ΔI / I _{0 ISM.} measured current values with relative differences

calculated current values, where
ΔI / I _0ism. = (I _0izm. -I _1izm. ) / I _0izm. , but

and

- the relative differences of the current values of the gun, calculated for two different longitudinal displacements of the cathode Δk ₁ and Δk ₂ at the same voltage values U ₀ , U ₁ on the PV, and the determination of Δk based on this comparison is carried out according to the formula:

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