Langmuir probe sheath size dynamics under medium pressure

This study investigates the time required for the stabilization of the sheath 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. We present an algorithm for the characterization of the sheath radius and calculate the transition time of the sheath radius after a sudden change of the probe potential. The observed transition times in collisional plasmas are well described by a model based on the ion mobility. In general, the sheath radius stabilizes at a rate that is faster than or equal to the rate of probe current stabilization. The radius of the sheath potential expands up to twice during the stabilization.