NUMERICAL-SIMULATION OF A NANOSECOND DISCHARGE IN HELIUM AT ATMOSPHERIC-PRESSURE, DEVELOPING IN THE REGIME OF RUNAWAY OF ELECTRONS

This paper presents a one-dimensional numerical model of a pulsed high -voltage discharge in dense gas developed under the influence of the n onlocal phenomenon of runaway of electrons. The model is self-consiste nt and takes into account the kinetics of charged particles, ionizatio n processes, the fields of space charges, and the external source of h igh-voltage pulses. A new version of large energy groups of electrons is adopted for overcoming the difficulties caused by the necessity of simultaneous inclusion of intensive multiplication of charged particle s and of the phenomenon of runaway electrons. The set of coordinates ( x, v, t) is used for analyzing the kinetics of electrons. Calculations are conducted for the case of a nanosecond discharge in helium at atm ospheric pressure in a centimeter-scale electrode gap under conditions of multiple overvoltage. Calculations are brought up to the relations describing the time dependence of the voltage across the gap and of t he total current in the circuit. The results are checked against oscil lograms.