Investigation of plasma filament decay in gases at different pressures

Properties of the plasma filaments have been studied in numerous publications. Of primary interest among them are the plasma density in a filament and its decay. Filaments were generally studied in ambient air, whereas filament plasma density decay in other gases and at different pressures has not been investigated yet. In this work, plasma filament decay in air, N₂ and Ar for pressure range 1-760 Torr were considered. To measure plasma density decay in the filament, transverse optical interferometry and pulsed terahertz scattering techniques were used. To simulate the observed plasma filament decay at various pressures, a set of balance equations for electrons and ions simultaneously with the balance equation for electron temperature were solved numerically.The analysis of the results allowed us to determine the dominant mechanisms of filament plasma decay in air, N2 and Ar at various pressures.