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On the relativistic large-angle electron collision operator for runaway avalanches in plasmas

  • O. Embréus (a1), A. Stahl (a1) and T. Fülöp (a1)

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.

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Journal of Plasma Physics
  • ISSN: 0022-3778
  • EISSN: 1469-7807
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