Ionization growth in the breakdown of plasma focus discharge

Abstract The non-stationary electron energy distribution function (EEDF) in the breakdown phase of the discharge in a plasma focus (PF) is studied through Monte Carlo simulations. It is found that EEDF substantially deviates from the Maxwellian distribution. The time evolution of the electron density is investigated up to 14 ns after the initiation of the breakdown process. During this time interval the avalanche electrons rapidly concentrate near the insulator/cathode edge and move slowly toward the exit of the plasma focus device. Throughout the breakdown the EEDF is characterized by an anomalous number of high-energy ( e> 100 eV) and low-energy ( e 10 eV) electrons. Our numerical simulations describe the beginning of the breakdown phase in a PF discharge more precisely than the existing hydrodynamic models.