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Title: Revised Knudsen-layer reduction of fusion reactivity

Recent work by Molvig et al. [Phys. Rev. Lett. 109, 095001 (2012)] examined how fusion reactivity may be reduced from losses of fast ions in finite assemblies of fuel. In this paper, this problem is revisited with the addition of an asymptotic boundary-layer treatment of ion kinetic losses. This boundary solution, reminiscent of the classical Milne problem from linear transport theory, obtains a free-streaming limit of fast ion losses near the boundary, where the diffusion approximation is invalid. Thermonuclear reaction rates have been obtained for the ion distribution functions predicted by this improved model. It is found that while Molvig's “Knudsen distribution function” bounds from above the magnitude of the reactivity reduction, this more accurate treatment leads to less dramatic losses of tail ions and associated reduction of thermonuclear reaction rates for finite fuel volumes.
Authors:
; ; ; ; ; ;  [1] ;  [2]
  1. Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States)
  2. Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185-1186 (United States)
Publication Date:
OSTI Identifier:
22218352
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 12; Other Information: (c) 2013 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; APPROXIMATIONS; ASYMPTOTIC SOLUTIONS; BOUNDARY LAYERS; DISTRIBUTION FUNCTIONS; MILNE PROBLEM; PLASMA; TAIL IONS; THERMONUCLEAR FUELS; THERMONUCLEAR REACTIONS; THERMONUCLEAR REACTORS; TRANSPORT THEORY