D.S. Makhanko

JSC Research Institute of Gas-Discharge Devices (Ryazan, Russia)

Uncontrolled spark gap-sharpeners are one of the main elements of any high-voltage pulse generator using to generate high-voltage pulses with amplitudes of hundreds of kilovolts and a duration of the leading edge of the pulse of units and tenths of a nanosecond. The application area of spark gap-sharpeners as a part of high-voltage pulse generators are portable X-ray sources, accelerator equipment, sources of pumping gas-discharge lasers of superatmospheric pressure, electron-optical converters and photo recorders of pico- and femtosecond radiation processes. The main requirements for spark gap-sharpeners are minimal geometric dimensions, nano- and subnanosecond response times, high (up to 500 kV) electrical strength of the ceramic insulator and the gap between the high-voltage connector and the casing of the spark gap-sharpener. To ensure high switching characteristics in spark gap-sharpeners, hydrogen is used as a working medium at pressures up to 120 atmospheres. High pressure values impose very strict requirements on the mechanical strength of both individual components and the design of the spark gap as a whole. It is also necessary to correctly select the used electro-vacuum materials, which provide high mechanical strength and vacuum density of metal-metal and metal-ceramic joints. The construction of the spark gap-sharpener operating in the nanosecond time range should take into account the possibility of matching with lines forming high-voltage pulses of nanosecond duration.

In this article, the problem of manufacturing uncontrolled high-pressure spark gap-sharpeners with operating voltages up to 500 kV is discussed. The aim of the work is to develop practical recommendations for the manufacture of uncontrolled gas-filled sealed off spark gap-sharpeners in metal-ceramic design, providing minimum geometric dimensions at voltages up to 500 kV, subnanosecond response times and a resource of at least 3x106 inclusions in a given operating mode. The process of soldering the cathode metal-ceramic unit using silver solder PSr 72, the process manufacturing the anode unit using the two-stage soldering method, and describes the filling and training of the spark gap with electronegative gas to increase the electrical strength. Soldering at elevated temperature according to the mode described in this work contributes to better wetting of the soldered surfaces with solder, its faster spreading and filling of the covering seams, and also provides capillary filling of the edge seams.

With a sharp change in the soldering temperature, the solder in the edge joint begins to melt from the outside to the inside of the seam (with the external location of the heating elements in the furnaces relative to the seam). Moving the molten solder from the outside to the inside of the seam significantly improves the structure of the seam and, as a result, the mechanical and thermal characteristics of the ceramic-metal connection. A promising direction for improving the quality of manufactured spark gap-sharpeners and other complex structures of devices with simultaneous use of both edge and covering metal-ceramic and metal junctions is the use of the technology of soldering of metal-ceramic assemblies given in this article with a significant excess of the soldering temperature, the rate of temperature change and exposure during soldering, depending on the design features of the products. The method described in this article for manufacturing a gas-filled metal-ceramic spark gap-sharpener made it possible to ensure high reliability and tightness of the device. Additional training of high-voltage spark gap-sharpeners in SF6 gas or its mixtures with inert gas and/or nitrogen can significantly increase the electrical strength of the arrester. The industrial production of a series of spark gap-sharpeners of the RO – 48, – 43, – 49, – 72 type has been mastered  for operating voltages from 100 to 500 kV for use mainly in pulsed X-ray technology. Using the manufacturing method described in this work, the percentage of usable products increased to 95% during the mass production of spark gap-sharpeners.

Makhanko D.S. Manufacturing technology of sealed off high-pressure spark gap-sharpeners with voltages up to 500 kilovolts. Science Intensive Technologies. 2022. V. 23. № 1. P. 5−13. DOI: https://doi.org/10.18127/j19998465-202201-01 (in Russian)

1. Mesyac G.A. Impul'snaya energetika i elektronika. M.: Nauka. 2004. 704 s.
2. Mesyac G.A. Generirovanie moshchnyh nanosekundnyh impul'sov. M.: Sov. radio.1974. 256 s.
3. Koval'chuk B. M., Kremnev V. V., Potalicyn Yu. F. Sil'notochnye nanosekundnye kommutatory. Novosibirsk: Nauka. Sib. otd. 1979. 175 s.
4. Morgovskij L.Ya., Peliks E.A. Impul'snaya rentgenografiya. Apparaty serii «Arina». SPb.: Sinus p. 1999. 75 s.
5. Sorokin D.A., Beloplotov D.V., Grishkov A.A. i dr. Vysokovol'tnyj nanosekundnyj razryad v neodnorodnom elektricheskom pole i ego svojstva. Tomsk: STT. 2020. 288 s.
6. Merkulov B.P., Mel'nichuk G.V., Mahan'ko D.S., Merkulov D.B. Bazovaya konstrukciya gazonapolnennogo metallokeramichesko-go razryadnika vysokogo davleniya dlya impul'snyh istochnikov rentgenovskogo izlucheniya. Oboronnyj kompleks – nauchno-tekhnicheskomu progressu Rossii. 2013. № 1. S. 44–51.
7. A.s. SSSR №1431588, kl. N01J 17/00. Gazonapolnennyj razryadnik. E. A. Avilov, Belkin N. V., B. P.Merkulov. Ryazan', 1991. 6 s.
8. Locmanov S. N., Petrunin N. E., Frolov V. P. Spravochnik po pajke. M.: Mashinostroenie. 1975. C. 292–293.
9. Patent na izobretenie № RU2550350S2 N01J 17/02. Cposob izgotovleniya gazonapolnennogo razryadnika /
   B.P. Merkulov, D. S. Mahan'ko, N. I. Cherepennikova, T.G. Novikova. Ryazan'. 2015. 15 s.
10. Kiselev Yu. V., Cherepanov V. P. Iskrovye razryadniki. M.: Sov. radio. 1976. 67 s.
11. Patent na izobretenie RU2313849S1 N01J 17/20. Sposob izgotovleniya razryadnika. B. P. Merkulov, V.G. Samorodov. Ryazan'. 2006. 5 s.
12. Patent na izobretenie RU2697264S1 N01J 17/02 H01J 9/38. Sposob izgotovleniya razryadnika s vodorodnym napolneniem. B.P. Merkulov, D.S. Mahan'ko, N.I. CHerepennikova. Ryazan'. 2018. 14 s.