Hybrid model of runaway electrons generation process in nanosecond high pressure gas discharge

Summary form only given. The paper deals with the results of theoretical modeling of runaway electrons generation which occurs in the high-pressure nanosecond pulsed gas breakdown. For these purposes a novel hybrid model of the gas discharge has been successfully built. It uses hydrodynamic and kinetic approaches simultaneously to describe the dynamics of different components of low-temperature discharge plasma. Namely, it uses corresponding equations of continuity with drift-diffusion approximation to consider motion of ions and low-energy (Maxwellian) electrons. On the other hand the description of high-energy (runaway) electrons is implemented by including the Boltzmann kinetic equation. Also this system is completed by Maxwell equations set to take into the account the agreed electric field distribution.Numerical solution of equations system allows to describe in details spatial and temporal structure of the plasma, the electric field distribution, as well as the quantity and energy spectrum of runaway electrons that are generated at highvoltage breakdown stage of nanosecond discharge. In contrast to the numerical methods operating with restricted ensemble of particles (i.e. Monte Carlo methods, PIC methods, etc.), the proposed approach allows to calculate the spectrum of a statistically small amount of fast electrons. In particular, it was shown that spectrum of fast electrons at anode depends on the peculiarities of the plasma density and electric field distributions at non-stationary stage of the gas breakdown.