D.A. Sorokin

The physical nature of electrons with “anomalous” energies in fast atmospheric discharges

This paper deals with the phenomenon of runaway electrons generation in fast discharges under atmospheric pressures. For the first time we explain the existence of runaway electrons having so-called “anomalous” energies (above the applied voltage value) according to physical kinetics principles. The model we consider provides comprehensive information on the formation and development of runaway electron beams with respect to different initial experimental conditions. The numerical results we obtain fit the existing experimental data for discharges in air.

Parameters of runaway electron beam generated during excitation by nanosecond voltage pulses in short gaps filled with nitrogen

Parameters of a supershort avalanche electron beam (SAEB) in nitrogen excited by the triangular-shaped voltage pulses with 45kV amplitude in incident wave and full width at half-maximum (FWHM) of ~ 1 ns were investigated. In experiments, cylindrical-shaped cathodes made of aluminum and stainless steel were used. An interelectrode distance in the gas-filled diode was 3, 5, and 8 mm. It was established that the highest values of SAEBs current were registered with an aluminum cathode. It was shown that, in contrast to the case of 8-mm gap length, when the interelectrode distances were 3 and 5 mm, the amplitude of SAEB current pulse in nitrogen began to decrease with high values of the pressure – 100 and 50 kPa, respectively.

Nanosecond discharges with runaway electrons and X-rays in atmospheric pressure air, nitrogen, CH 4 , SF 6 , xenon, krypton, argon and helium

Diffuse discharges were formed in a highly nonuniform electric field by point-plane gaps in atmospheric pressure air, nitrogen, CH4, SF6, xenon, krypton, argon and helium by two nanosecond-pulse generators. The rise time of generators were 0.3 (SLEP-150) and 1 ns (RADAN-220), and a full width at half maximum (FWHM) were 1 and 2 ns, respectively. The variables affecting the discharge characteristics, including the gap spacing d and applied pulse parameters, were investigated. With both generators supershort avalanches electron beam (SAEB) and X-rays were obtained. The characteristics of measured SAEB and X-rays on the all generators were studied. With Generator #1 in atmospheric pressure air it was obtained that FWHM of the total SAEB current pulse from the entire foil area is ̃ 100 ps and the amplitude of SAEB ̃ 100 A. With Generator #2 in all gases at the pressure of one atmosphere SAEB was registered.

Change of the e-beam generation mode at transition from the vacuum to the gas-filled diode

In this paper, characteristics of the runaway electron beams downstream of a foil anode were studied at a pressure of helium, hydrogen, and nitrogen from vacuum to tens of torr. High-voltage pulses (~150 and ~250 kV) with pulse rise times of ~300 and ~500 ps were applied to the tubular cathode - plane anode gap. It is demonstrated that increasing the pressure from vacuum to 10 of torr and more changes the mode of the electron beam generation and can increase the beam current amplitude. It is shown that increasing the pressure of helium, hydrogen, and nitrogen allows continuously adjusting the electron beam duration from ~500 to ~100 ps (FWHM).

Generation of a supershort avalanche electron beam in a subnanosecond breakdown in different gases at pressures from 1 torr to 15 atm

The paper considers the properties of a supershort avalanche electron beam (SAEB) produced in different gases at the pressures from 1 torr to 15 atm. The SAEB downstream of a gas diode foil was detected at sulphur hexafluoride and xenon pressures up to 2 atm, nitrogen pressure up to 5 atm, and helium pressure up to 15 atm. It is demonstrated that at an air pressure of 1 atm, the SAEB is generated into an angle larger than 2 π sr. It is shown that the highest amplitudes of a SAEB of short duration are attained in different gases at low pressures.

High power UV and VUV pulsed excilamp

This paper reports on the pulse sources of spontaneous UV and VUV radiation based on the non-equilibrium high-pressure gas discharge plasma. Emission characteristics of a runaway preionized diffuse discharge plasma of inert gases and its halogenides under pressure up to 12 atm and at high specific power of excitation (up to ∼100 MW/cm3) have been investigated.