On the relativistic large-angle electron collision operator for runaway avalanches in plasmas
Abstract
Large-angle Coulomb collisions lead to an avalanching generation of runaway electrons in a plasma. We present the first fully conservative large-angle collision operator, derived from the relativistic Boltzmann operator. The relation to previous models for large-angle collisions is investigated, and their validity assessed. We present a form of the generalized collision operator which is suitable for implementation in a numerical kinetic equation solver, and demonstrate the effect on the runaway-electron growth rate. Finally we consider the reverse avalanche effect, where runaways are slowed down by large-angle collisions, and show that the choice of operator is important if the electric field is close to the avalanche threshold.
- Publication:
-
Journal of Plasma Physics
- Pub Date:
- February 2018
- DOI:
- 10.1017/S002237781700099X
- arXiv:
- arXiv:1708.08779
- Bibcode:
- 2018JPlPh..84a9002E
- Keywords:
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- fusion plasma;
- runaway electrons;
- Physics - Plasma Physics
- E-Print:
- 18 pages, 6 figures