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Sheath Physics and Boundary Conditions for Edge Plasmas
Author(s) -
Cohen R. H.,
Ryutov D. D.
Publication year - 2004
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.200410016
Subject(s) - plasma , physics , toroid , boundary value problem , momentum (technical analysis) , enhanced data rates for gsm evolution , boundary (topology) , ion , magnetic field , mechanics , electron , charge (physics) , atomic physics , computational physics , nuclear physics , quantum mechanics , mathematics , telecommunications , mathematical analysis , finance , computer science , economics
The boundary conditions of mass, momentum, energy, and charge appropriate for fluid formulations of edge plasmas are surveyed. We re‐visit the classic problem of 1‐dimensional flow, and note that the “Bohm sheath criterion” is requirement of connectivity of the interior plasma with the external world, not the result of termination of the plasma by a wall. We show that the nature of the interior plasma solution is intrinsically different for ion sources that inject above and below the electron sound speed. We survey the appropriate conditions to apply, and resultant fluxes, for a magnetic field obliquely incident on a wall, including the presence of drifts and radial transport. We discuss the consequences of toroidal asymmetries in wall properties, as well as experimental tests of such effects. Finally, we discuss boundary‐condition modifications in the case of rapidly varying plasma conditions. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)