Numerical Study of Non-Linear Effects for a Swept Bias Langmuir Probe

Abstract

We present a numerical study disclosing non-linear effects and hysteresis loops for a swept bias Langmuir probe. A full kinetic particle in cell (PIC) model has been used to study the temporal sheath effects and the probe current. Langmuir probes are normally operated at low frequencies, since a 'close to steady state' condition is required to characterize the plasma. However, during operations above frequencies normally used, capacitive and non-linear resistive effects are being unveiled. We demonstrate how ion and electron density and temperature change properties of the probe-plasma system. We also show that a swept Langmuir probe exhibits essential properties described as the 'fingerprint of memristors' and how a Langmuir probe can be identified as a transversal memristor. Understanding non-linear processes might enable new ways to operate Langmuir probes with higher sampling rates and better accuracy.