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Title: Application of diffusion theory to neutral atom transport in fusion plasmas

Abstract

It is found that energy dependent diffusion theory provides excellent accuracy in the modelling of transport of neutral atoms in fusion plasmas. Two reasons in particular explain the good accuracy. First, while the plasma is optically thick for low energy neutrals, it is optically thin for high energy neutrals and diffusion theory with Marshak boundary conditions gives accurate results for an optically thin medium even for small values of 'c', the ratio of the scattering to the total cross section. Second, the effective value of 'c' at low energy becomes very close to one due to the down-scattering via collisions of high energy neutrals. The first reason is proven both computationally and theoretically by solving the transport equation in a power series in 'c' and the diffusion equation with 'general' Marshak boundary conditions. The second reason is established numerically by comparing the results from a one-dimensional, general geometry, multigroup diffusion theory code, written for this purpose, with the results obtained using the transport code ANISN.

Authors:
; ;
Publication Date:
Research Org.:
California Univ., Los Angeles (USA). Dept. of Mechanical, Aerospace and Nuclear Engineering
OSTI Identifier:
5628647
Report Number(s):
UCLA/PPG-902
ON: DE86010913
DOE Contract Number:
AS03-80ER52062
Resource Type:
Technical Report
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; PLASMA; TRANSPORT THEORY; PLASMA DRIFT; ATOMS; BOUNDARY CONDITIONS; CROSS SECTIONS; DIFFUSION; SCATTERING; 700105* - Fusion Energy- Plasma Research- Plasma Kinetics-Theoretical- (-1987)

Citation Formats

Hasan, M.Z., Conn, R.W., and Pomraning, G.C.. Application of diffusion theory to neutral atom transport in fusion plasmas. United States: N. p., 1986. Web. doi:10.2172/5628647.
Hasan, M.Z., Conn, R.W., & Pomraning, G.C.. Application of diffusion theory to neutral atom transport in fusion plasmas. United States. doi:10.2172/5628647.
Hasan, M.Z., Conn, R.W., and Pomraning, G.C.. Thu . "Application of diffusion theory to neutral atom transport in fusion plasmas". United States. doi:10.2172/5628647. https://www.osti.gov/servlets/purl/5628647.
@article{osti_5628647,
title = {Application of diffusion theory to neutral atom transport in fusion plasmas},
author = {Hasan, M.Z. and Conn, R.W. and Pomraning, G.C.},
abstractNote = {It is found that energy dependent diffusion theory provides excellent accuracy in the modelling of transport of neutral atoms in fusion plasmas. Two reasons in particular explain the good accuracy. First, while the plasma is optically thick for low energy neutrals, it is optically thin for high energy neutrals and diffusion theory with Marshak boundary conditions gives accurate results for an optically thin medium even for small values of 'c', the ratio of the scattering to the total cross section. Second, the effective value of 'c' at low energy becomes very close to one due to the down-scattering via collisions of high energy neutrals. The first reason is proven both computationally and theoretically by solving the transport equation in a power series in 'c' and the diffusion equation with 'general' Marshak boundary conditions. The second reason is established numerically by comparing the results from a one-dimensional, general geometry, multigroup diffusion theory code, written for this purpose, with the results obtained using the transport code ANISN.},
doi = {10.2172/5628647},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu May 01 00:00:00 EDT 1986},
month = {Thu May 01 00:00:00 EDT 1986}
}

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