A full-angle Monte-Carlo scattering technique including cumulative and single-event Rutherford scattering in plasmas

JOURNAL OF COMPUTATIONAL PHYSICS

卷:349

Article

Higginson, Drew P.¹ 

[1] Lawrence Livermore Natl Lab, Livermore, CA 94551 USA

关键词: Coulomb collisions;    Large-angle collisions;    Numerical methods;    Monte-Carlo methods;    Collisional plasma;    Inertial confinement fusion;   

DOI  :  10.1016/j.jcp.2017.08.016

来源: Elsevier

【 摘 要 】

We describe and justify a full-angle scattering (FAS) method to faithfully reproduce the accumulated differential angular Rutherford scattering probability distribution function (pdf) of particles in a plasma. The FAS method splits the scattering events into two regions. At small angles it is described by cumulative scattering events resulting, via the central limit theorem, in a Gaussian-like pdf; at larger angles it is described by single-event scatters and retains a pdf that follows the form of the Rutherford differential cross-section. The FAS method is verified using discrete Monte-Carlo scattering simulations run at small timesteps to include each individual scattering event. We identify the FAS regime of interest as where the ratio of temporal/spatial scale-of-interest to slowing-down time/length is from 10(-3) to 0.3-0.7; the upper limit corresponds to Coulomb logarithm of 20-2, respectively. Two test problems, high-velocity interpenetrating plasma flows and keV-temperature ion equilibration, are used to highlight systems where including FAS is important to capture relevant physics. (C) 2017 Published by Elsevier Inc.

【 授权许可】

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