SU1191978A1 - Gaseous-discharge switching device - Google Patents

Abstract

A GAS DISCHARGE COM1-1UTHING DEVICE containing cylindrical coaxial electrodes and a control coil, characterized in that, in order to improve the energy characteristics and control of ignition and discharge quenching without reducing the current and voltage blocking capacity, the electrode is made in the form of two sections of different diameter, and the control coil is in the form of two sections of different length, with the length of the coil section mounted above the space of the larger electrode gap and made with a length, The full length of the inner electrode section is smaller in diameter, the short coil section is set to the smaller interelectrode gap at a distance from the long coil section that is at least two times smaller than the smaller interelectrode gap, and the smaller (2 interelectrophe f, and smaller native gaps are chosen from ratios cC, T2RL ,, where RL, Ri are the cyclotron radii of the electron, corresponding to the switching voltage and the voltage to maintain the discharge. ,

Description

I. The invention relates to electronic engineering, and more specifically to gas discharge switching devices with magnetic control, designed for controlled ignition and discharge suppression, and can be used in various high-power impulse installations. The aim of the invention is to improve the energy and control characteristics of ignition and discharge suppression without reducing the current and voltage switching capacity by reducing the control power. FIG. 1 shows a device diagram; in fig. 2 - current diagram The gas discharge switching device contains two cylindrical coaxial electrodes 1 and 2. The internal electrode consists of two sections 3 and 4, forming two interelectrode gaps 5 and 6. On the side of them the section 7 of the roller 7 is installed, and the smaller side is the coil section 8. The device is filled with low pressure gas, which is determined from the condition (Tor), where. Aj is the electron mean free path at 1 Torr to provide the necessary electrical stability in accordance with the left branch of the Paschen curve. Each of them is covered by its own control coil (6 and 7); The length of the coil 7 for the gap 5 (main) with a large interelectrode distance is equal to its length along the axis, and the length of the coil 8 for the second gap 6 (auxiliary) is less than its length. The distance between the sections of the coils 7 and 8 from the first gap is chosen such that it is more than twice as large as the interelectrode distance of the second gap, i.e. 7 2SK-G2). The boundary values for the choice of the interelectronic distance of the first gap (Rr are as follows. To ensure stable ignition, it must at least twice exceed the cyclotron radius of electrons with a switched anode voltage. The increase in the interelectrode distance of the first gap (decrease in r is limited by cooling conditions anode (the discharge burns most of the time in the first gap) and the need to ensure the electrical strength of the device in accordance with the left branch of the Paschen curve. Practice shows that From the point of view of providing electrical strength in the range of 10–40 kV, the value of the product p (Rr) for hydrogen should be in the order of 0.3 mm Hg. For example, at a hydrogen pressure of 0.1.The torrent distance between the first gap can be chosen up to 3 cm, with a pressure of 0.05 Torr, it can be increased to 6 cm. As for the interelectrode distance of the second gap, its value should exceed two cyclotron radii when the discharge voltage maintains (/ 400 v) In this case a steady discharge is already provided. However, in view of zmozhnosti of vacuum breakdown phenomena in the initial mode, and when applied to electrodes switched high voltage, the interelectrode distance of the second gap do not take less. 34 cm. Switching device. Sequentially connected to the high voltage circuit. When applying to the first (main) gap 5 of the magnetic field pulse H (Fig. 2) of duration T, a bit shorter than the duration of the discharge current IP (Tj), the main gap 5 ignites the discharge in crossed fields, ensuring the passage of the discharge current. The pulse of the magnetic field H2 is supplied to the second (auxiliary) gap 6 at the moment of time preceding by the value if, equal to several microseconds, to the end of the pulse H so that a steady discharge is formed in it. The duration of the pulse; H Ctj is set to 10-15 x. During this time, the plasma in the first gap completely disintegrates, and its electrical strength is restored. At the end of the pulse H, the bit in the second gap goes out and the device shuts off completely. Thus, the energy characteristics of the device during the conduction period and the characteristics of the ignition control of the discharge are provided by the first (main) gap. The second (auxiliary) period is switched on only briefly at a time instant close to the end of the discharge current.

n defines control characteristics for discharge quenching.

The effect of the second gap plasma on the deionization process in the first gap is almost insignificant due to the removal of the second coil and, accordingly, the discharge plasma of the second gap (the length of the discharge in a magnetic field in the coaxial electrode system is determined by the length of the magnetic coil).

Plasma deionization between two coaxial cylinders in the longitudinal direction decreases exponentially in proportion to the magnitude (length of cylinders, d - distance between them), therefore already twice the value compared to the interelectrode distance of the second gap ensures reliable screening of the first gap from the second.

 The pulse duration H is determined by the duration of the discharge current tj and is equal to

g- - fr g - l

H Gr v va -2 To estimate the values of H can be from the expression

Yu.

| (

p.1

g 2-g 2

 k o

where K is a constant, depending on the first and third Townsend coefficients, on the ratio of the electron charge to mass;

r and the radii of the cathode and anode, respectively;

and - switching voltage. This expression is obtained for the case of a uniform magnetic field. When using hydrogen as a filling gas with pressure / vO, 1 Torr, it is possible to accept with a sufficient degree of approximation, 5 and then

3 j 5jy

H -,

er

i

(g 2) 1 IlL

   tt -p g

- N

Here, and should. Choose in volts, G | and Gd - centimeters, In this device

„-BS-ffi - HTr -Si-rT | (R-r;) i, 5 -Jw-riji l, where U, c is switching voltage; UD - discharge hold voltage,

1919784

With the same switching voltage we have

Rr

lii

. -,

show what

N.

 year

those. It can be said that the magnitudes of 10 magnetic fields of different discharge gaps with the same switching voltage are inversely proportional to their interelectrode distances. Thus, the use of two gaps in the device, differing in the interelectrode distance, allows to improve the energy characteristics of the device, reduce power control device. 20 The transfer of the discharge into the gap with a smaller interelectrode distance makes it possible to increase the switched capacity of the proposed device with respect to current, since the probability of the discharge going into an out of control magnetic field the arc mode decreases with a decrease in the distance between the electrodes,

In order to test the technical efficiency of the device, 2 layouts were tested. One model of the device contains the usual coaxial system of electrodes (as izvesgnogo), with an interelectrode distance of 4 mm (model No. 1), the second model was made in accordance with the invention and contained two spacers with an interelectrode distance of 16 mm (first) and 4Mfi ( second), each of which. Q. was covered by a separate control coil, the distance between the coils was 10 mm. The cathode radius in both models was 25 mm, the cathode height was 60 mm. The height of the working part e of the cathode (the length of the main section, the gap) was chosen to be 4 cm and determined by the length of the coil) (in layout No. 2, this is the first main coil). All tests were run at switching voltage of kV and pressure of hydrogen, established by means of a hydrogen generator, xO, Thor,

5 The results of the survey layouts are summarized in the table.

Hence, the ratio of the power of control-, laziness in the known device to the power of control in the proposed device is equal to

.e

The ratio of the energy losses in the discharge gap in the known device to the energy losses

The maximum anode current at which) a stable shutdown of the device occurs without removing the high voltage, A Turn-off time of the device, (the time of the anodic current falling from the level of 0.9 to the level of O, 1), ISS

Voltage drop on the device during the conducting period, V

The minimum value of the magnetic field, which ensures stable ignition of the discharge, E

Duration of discharge current, ms

The duration of the magnetic field, ms: The main coil

Auxiliary coil

The value of the magnetic field of the auxiliary coil at which the voltage drop in the second gap is the same as in the first, E

IP

230

1.5. 380

BUT 180

170 12

180

6G

Claims (1)

GAS-DISCHARGE COMMUTING DEVICE containing cylindrical coaxial electrodes and control-. a coil, characterized in that, in order to improve the energy and control characteristics of the ignition and quenching of the discharge without reducing the switching ability of current and voltage, the inner electrode is made in the form of two sections of different diameters, and the control coil in the form of two sections different lengths, with the long coil section mounted above the space of the larger interelectrode gap and made with a length equal to the length of the inner electrode section of the smaller diameter, the short coil section is installed from the side of the smaller interelectrode gap at a distance from the long section of the coil, which is at least twice as large as the smaller interelectrode gap, and the values of the larger and smaller interelectrode gaps are selected from the ratios ^ 7 2R _Li , ^ 7 2R ₄ cyclotron radii of the electron corresponding to the switching voltage and voltage maintaining discharge. , - Fig .. / 8Z6l6irnS 1 19