Measurement of stream instability of Argon-Xenon plasma

Abstract

Previous experiments had shown the existence of ion-ion beam instability in weakly collisional Argon-Helium plasma in the pre-sheath near a negatively biased plate. [1] A new theory [2] suggests that this instability enhances the collisional friction between the ion species and determines their velocities at the sheath-presheath boundary. Here we report experimental measurements of the ion-ion instability in Argon-Xenon plasma carried out in conjunction with LIF velocity measurements. Instability is measured by a cylindrical probe collecting electron saturation current. Ion Acoustic Wave phrase velocity measurement is employed to determine the relative ion concentrations. Electron temperature is measured by a Langmuir probe and the sheath locations are determined by an emissive probe [3].