Runaway-electron formation and electron slide-away in an ITER post-disruption scenario

Abstract

Mitigation of runaway electrons is one of the outstanding issues for the reliable operation of ITER and other large tokamaks, and accurate estimates for the expected runaway-electron energies and current are needed. Previously, linearized tools (which assume the runaway population to be small) have been used to study the runaway dynamics, but these tools are not valid in the cases of most interest, i.e. when the runaway population becomes substantial. We study runaway-electron formation in a post-disruption ITER plasma using the newly developed non-linear code NORSE, and describe a feedback mechanism by which a transition to electron slide-away can be induced at field strengths significantly lower than previously expected. If the electric field is actively imposed using the control system, the entire electron population is quickly converted to runaways in the scenario considered. We find the time until the feedback mechanism sets in to be highly dependent on the details of the mechanisms removing heat from the thermal electron population.

arXiv commentJoint Varenna-Lausanne International Workshop on the Theory of Fusion Plasmas, Varenna, Italy, 2016. 8 pages, 4 figures

References in corpus (5)

• Conductivity of a Relativistic Plasma
• Effective Critical Electric Field for Runaway-Electron Generation
• Numerical calculation of the runaway electron distribution function and associated synchrotron emission
• Kinetic modelling of runaway electrons in dynamic scenarios
• Differential Form of the Collision Integral for a Relativistic Plasma

Cited by in corpus (3)

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