RU2241277C1 - Method for raising electric strength of vacuum insulation - Google Patents

Abstract

FIELD: high-voltage and vacuum-insulation engineering for electronic industry.

SUBSTANCE: vacuum space is aged by single high-voltage pulses whose length is shorter than that of operating voltage and polarity corresponds to operating voltage polarity at amplitudes supporting breakdown delay time equal to length of condensing pulse.

EFFECT: enhanced electric strength of vacuum insulation.

1 cl, 1 dwg

Description

The invention relates to techniques for high voltage, in particular to the field of electrical insulation in vacuum, and can be used in the electronics industry to increase the electrical strength of the vacuum insulation of vacuum devices and structures.

A known method of increasing the electric strength of vacuum insulation, including training the vacuum gap with high-voltage breakdowns at a pulse voltage [1].

The disadvantage of this method is that the training is carried out by pulses of long duration, while it is not possible to provide a significant improvement in the microrelief of the cathode surface and increase the electrical strength of the vacuum insulation compared to training breakdowns of direct current.

The closest technical solution, selected as a prototype, is a method of increasing the dielectric strength of vacuum insulation [2]. The method includes training the vacuum gap with single high-voltage breakdowns of the pulse voltage of a shorter duration than the duration of the operating voltage, with a polarity corresponding to the polarity of the operating voltage.

However, this method of increasing the dielectric strength of vacuum insulation does not optimize the amplitude of the pulse voltage.

The problem to which the invention is directed, is to increase the efficiency of the method by optimizing the amplitude of the high voltage pulses.

This is achieved by the fact that in the known method of increasing the electric strength of vacuum insulation, including training the vacuum gap with single high voltage pulses of shorter duration than the duration of the operating voltage, with a polarity corresponding to the polarity of the operating voltage, the training is carried out at amplitudes that maintain the breakdown delay time equal to the conditioning duration momentum.

The introduction of the training operation at amplitudes that maintain the breakdown delay time equal to the conditioning pulse duration t _s = t _and improves the efficiency of the method by optimizing the pulse amplitude.

According to the optimality criterion of pulse conditioning [3]

the energy released in the emitter during time t _{and the} action of the pulse remains constant and equal to the energy of its destruction.

The condition for optimizing pulsed conditioning, which improves the quality of the cathode surface and the dielectric strength of insulation, is to maintain the breakdown delay time equal to the conditioning pulse duration t _s = t _and . A means of unambiguously establishing the optimality condition is the oscillography of voltage or current pulses in the gap.

With a decrease in the duration of the pulses of the optimal mode, providing constant energy equal to the energy of its destruction in the emitter, the power of conditioning pulses and the effectiveness of the training increase. The greatest effect is achieved at t _and ≤ 10 ^-10 s.

The essence of the method is illustrated by a graph reflecting a change in the quality of the cathode surface and dielectric strength with a change in the duration of the conditioning pulses at amplitudes that maintain the breakdown delay time equal to the conditioning pulse duration.

A method of increasing the dielectric strength of vacuum insulation is as follows.

High voltage pulses of shorter duration than the duration of the operating voltage are supplied to the vacuum gap, increasing their amplitude to a value on the verge of breakdown occurrence. With the help of an oscilloscope, the breakdown delay time is monitored at the beginning of a sharp drop in voltage or current growth in the gap. By changing the amplitude, the delay time is maintained equal to the duration of the conditioning pulses and the training is performed until a steady-state amplitude value is reached.

To implement the method, a high-voltage nanosecond pulse generator is used.

According to the claimed method, using a nanosecond generator, which generated impulses with a voltage of 5 ≤ U _and ≤ 60 kV and a duration of 4 ≤ t _and ≤ 800 ns on an inconsistent load, copper electrodes were trained at an interelectrode gap of 0.5 mm, as well as chromium electrodes at d = 0.9 mm. The breakdown delay time and the conditioning pulse duration were controlled using an S-9-4A oscilloscope and a capacitive voltage divider. The results of processing the cathode by pulses of different durations t _and = t _{s are} estimated by the field gain and the characteristics of the insulation dielectric strength [4, 5]. The relative change in the field gain with a change in the duration of the conditioning pulses at amplitudes that maintain the breakdown delay time equal to the duration of the conditioning pulse determines the coefficient of change in the quality of the cathode surface and dielectric strength of the insulation.

The coefficient of change in dielectric strength was also calculated from known experimental data on the delay time of vacuum breakdown [6-12], corresponding to conditioning with pulses of duration equal to the time of breakdown delay.

The experimental results are presented in the form of a dependence of the coefficient of increase in electric strength on the duration of conditioning pulses.

From the curve shown in the drawing, it follows that the proposed method can improve the quality of the cathode surface and the dielectric strength of vacuum insulation to 2 orders of magnitude or more.

This method increases the efficiency of the known method of increasing the dielectric strength of vacuum insulation by optimizing the amplitude of high voltage pulses.

Sources of information

1. Slivkov I.N. Electrical insulation and discharge in a vacuum - M .: Atomizdat, 1972, S. 90.

2. A.S. USSR No. 550702. A way to increase the electrical strength of vacuum insulation. B.I. No. 10, 1977 / A.A. Emelyanov, G.M. Kassirov, G.V. Smirnov is a prototype.

3. Emelyanov A.A. On some modes of increasing the electrical strength of vacuum insulation // PTE, 1997. No. 5. S. 68-71.

4. Emelyanov A.A. On the optimal mode of electric pulse conditioning of sprayed electrodes in vacuum // PTE, 1997. No. 5. S. 68-71.

5. Emelyanov A.A. Experimental results on the effect of training with nanosecond pulses on the electrical strength of vacuum insulation // High voltage technique and electrical strength of vacuum insulation. - Tomsk, TPI. 1977. - S. 3-7.

6. Juttner B., Rohrbeck W., Wolff H. Time delay of vacuum sparks in the subnanosccond region // IXth IC PIG: Proc. - Bucharest, 1969, 140.

7. Kalyatsky I.I., Kassirov G.M., Smirnov G.V. and other Temporary characteristics of the breakdown of centimeter vacuum gaps // ZhTF, 1975. - T.45. - No. 7. - S. 1547-1550.

8. Kassirov G.M. The influence of the electrode material on the delay time of the discharge during electrical breakdown of the vacuum gap // ZhTF, 1966. - T. 36. - No. 10. - S. 1883-1885.

9. Mesyats G.A., Bugaev S.P., Proskurovsky D.I. et al. Investigation of the initiation and development of pulsed breakdown of short vacuum gaps in the nanosecond time range // RE, 1969. - T. 14. - No. 12. - S. 2222-2230.

10. Vavilov S.P., Mesyats G.A. Investigation of current growth during pulsed breakdown of millimeter vacuum gaps // Izv. universities. Physics, 1970. - No. 8. - S. 90-94.

11. Olendzskaya N.F., Salman M.A. Temporal characteristics of electrical breakdown in vacuum // ZhTF, 1970. - T. 40. - No. 2. - S. 333-337.

12. Chalmers I.D., Phukan B.D. Breakdown time lags in short vacuum gaps // Vacuum, 1982. - V.32. - No. 3. - P.145-150.

Claims (1)

A method of increasing the electrical strength of vacuum insulation, including training the vacuum gap with single high voltage pulses of shorter duration than the duration of the operating voltage, with a polarity corresponding to the polarity of the operating voltage, characterized in that the training is carried out at amplitudes that maintain the breakdown delay time equal to the conditioning pulse duration.