Relativistic electron distribution function of a plasma in a near-critical electric field

Journal Article · Sat Jul 15 04:00:00 EDT 2006 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2219428· OSTI ID:20860114

Sandquist, P; Sharapov, S E; Helander, P; Lisak, M ^[1]

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1. EURATOM-VR Association, and Department of Radio and Space Science, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)

A corrected relativistic collision operator is used to derive a Fokker-Planck equation for the distribution function of relativistic suprathermal electrons in a weakly relativistic plasma, which is then solved by a procedure similar to that employed in Connor and Hastie [Nucl. Fusion 15, 415 (1975)]. Analytical expressions are derived for the electron distribution function in plasmas with the electric field close to critical, which is typical of plasmas with grassy sawteeth on the Joint European Torus. A numerical solution is used for determining the normalization constant, which matches the relativistic region onto the weakly relativistic region. It is found that the scaling of the runaway rate with the electric field obtained by Connor and Hastie is a good approximation in spite of their use of an incomplete form of the collision operator not conserving number of particles. The present analysis determines the proportionality constant and introduces corrections to the earlier scaling of the runaway rate with respect to the electric field. The results obtained for the electron distribution function constitute a basis for studies of experimentally observed phenomena in near-threshold electric field plasmas with a significant suprathermal electron population.

• OSTI ID: 20860114
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 7 Vol. 13; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
APPROXIMATIONS
CORRECTIONS
DISTRIBUTION FUNCTIONS
ELECTRIC FIELDS
ELECTRON COLLISIONS
ELECTRONS
FOKKER-PLANCK EQUATION
ION COLLISIONS
NUMERICAL ANALYSIS
NUMERICAL SOLUTION
PLASMA CONFINEMENT
PLASMA INSTABILITY
RELATIVISTIC PLASMA
RELATIVISTIC RANGE
SAWTOOTH OSCILLATIONS
TOKAMAK DEVICES