Transient Phenomena in Probe Measurements in Low-Density Helium and Oxygen Plasma

Abstract

Measurements of the probe characteristics in the pulsed mode in oxygen and helium plasma are presented. The question on the thickness of the near-probe space charge layer in the electron–ion, electron–ion–ion, and ion plasma is discussed. It has been shown that the presence of negative ions in the plasma leads to a drastic decrease in the thickness of the ion layer. A model of the formation of a near-probe layer in nonstationary low-pressure plasma is proposed. It been shown that a space charge layer is formed in the time of 5–6 collisions of ions with neutral particles. It has been illustrated that the displacement current has a linear dependence on the potential applied to the probe. The question concerning the value of the dielectric constant of the plasma is discussed.