Langmuir probe current dynamics under medium pressure

This study investigates the current transition time of a cylindrical Langmuir probe as a function of background pressure using a 2D3V particle model of low-temperature plasma under an external electric field. The probe potential was set positive relative to the plasma potential, and the stabilization of the probe current after a sudden change of the probe potential was observed. The transition time approaches the ion plasma oscillation period in near-collisionless plasma conditions. In contrast, at higher pressures, the transition time is approximately governed by ion mobility, consistent with earlier experimental predictions.