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Finite Mean‐Free‐Path Effects in Tokamak Scrape‐Off Layers
Author(s) -
Cohen Ronald H.,
Rognlien Thomas D.
Publication year - 1994
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.2150340217
Subject(s) - mean free path , tokamak , physics , distribution function , monte carlo method , thermal conduction , computational physics , distribution (mathematics) , path (computing) , electron , energy (signal processing) , path length , atomic physics , statistical physics , plasma , nuclear physics , optics , quantum mechanics , mathematical analysis , statistics , mathematics , computer science , programming language
We address the problem of calculating the parallel electron heat conduction in a tokamak scrape off layer with non‐negligible mean free path. We develop a model distribution function based on pieces of Fokker‐Planck solutions, containing: a local Maxwellian at low energies, a modified Spitzer‐Härm distribution at energies below where the mean free path equals the distance to the nearest wall, a bounce‐averaged distribution at higher energies up to the confining potential energy, a filled‐in outgoing loss‐cone distribution at still higher energies, and finally an empty loss region at energies such that the mean free path exceeds the length of the field line. The model is compared with Monte Carlo simulations.