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Transport theory in self‐similar variables for neutrals atoms in an edge plasma
Author(s) -
Helander P.,
Krasheninnikov S. I.
Publication year - 1996
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.2150360245
Subject(s) - mean free path , plasma , physics , ionization , kinetic energy , ion , atomic physics , neutral particle , charged particle , charge (physics) , electron , classical mechanics , quantum mechanics
A family of analytical solutions to the Botzmann equation is found describing neutral atoms penetrating into a hot plasma whilst undergoing charge‐exchange, ionization, and recombination. It is shown that if the neutral mean‐free path divided by the scale length of ion temperature variation is constant, it is possible to introduce self‐similar variables in the kinetic equation. Since the mean‐free path increases with increasing energy, a one‐sided, high‐energy tail arises in the neutral distribution. This tail may contribute significantly to the heat and particle fluxes, which are nonlocal in character. When this is the case, the fluid approximation of these quantities breaks down at arbitrarily short mean‐free paths.