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Title: An analytic expression for the sheath criterion in magnetized plasmas with multi-charged ion species

The generalized Bohm criterion in magnetized multi-component plasmas consisting of multi-charged positive and negative ion species and electrons is analytically investigated by using the hydrodynamic model. It is assumed that the electrons and negative ion density distributions are the Boltzmann distribution with different temperatures and the positive ions enter into the sheath region obliquely. Our results show that the positive and negative ion temperatures, the orientation of the applied magnetic field and the charge number of positive and negative ions strongly affect the Bohm criterion in these multi-component plasmas. To determine the validity of our derived generalized Bohm criterion, it reduced to some familiar physical condition and it is shown that monotonically reduction of the positive ion density distribution leading to the sheath formation occurs only when entrance velocity of ion into the sheath satisfies the obtained Bohm criterion. Also, as a practical application of the obtained Bohm criterion, effects of the ionic temperature and concentration as well as magnetic field on the behavior of the charged particle density distributions and so the sheath thickness of a magnetized plasma consisting of electrons and singly charged positive and negative ion species are studied numerically.
Authors:
 [1]
  1. Physics Department of K. N. Toosi University of Technology, 15418-49611 Tehran (Iran, Islamic Republic of)
Publication Date:
OSTI Identifier:
22408371
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; ANIONS; BOHM CRITERION; BOLTZMANN STATISTICS; CATIONS; CONCENTRATION RATIO; ELECTRON DENSITY; ELECTRONS; HYDRODYNAMIC MODEL; ION DENSITY; ION TEMPERATURE; MAGNETIC FIELDS; MULTICHARGED IONS; PLASMA; PLASMA SHEATH