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Title: Collisionless “thermalization” in the sheath of an argon discharge

We performed kinetic Vlasov simulations of the plasma-wall transition for a low-pressure argon discharge without external magnetic fields, using the same plasma parameters as in the experiments of Claire et al. [Phys. Plasmas 13, 062103 (2006)]. Experimentally, it was found that the ion velocity distribution function is highly asymmetric in the presheath, but, surprisingly, becomes again close to Maxwellian inside the sheath. Here, we show that this “thermalization” can be explained by purely collisionless effects that are akin to the velocity bunching phenomenon observed in charged particles beams. Such collisionless thermalization is also observed in the presheath region close to the sheath entrance, although it is much weaker there and in practice probably swamped by collisional processes (standard or enhanced by instabilities)
Authors:
;  [1]
  1. Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS and Université de Strasbourg, BP 43, F-67034 Strasbourg (France)
Publication Date:
OSTI Identifier:
22408366
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ARGON; ASYMMETRY; BEAM BUNCHING; BOLTZMANN-VLASOV EQUATION; CHARGED PARTICLES; DISTRIBUTION FUNCTIONS; ELECTRIC DISCHARGES; FIRST WALL; ION BEAMS; MAGNETIC FIELDS; PLASMA; PLASMA SHEATH; PRESSURE RANGE KILO PA; THERMALIZATION