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

Artikel i vetenskaplig tidskrift, 2016

Mitigation of runaway electrons is one of the outstanding issues for a reliable operation of ITER and other large tokamaks, and accurate estimates for the expected runaway- electron energies and current are needed. Previously, linearized tools, assuming 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 nd that the entire electron population is converted to runaways in the scenario considered. A new non-linear feedback mechanism is also described, by which a transition to electron slide-away can be induced at eld strengths signi cantly lower than previously expected. We nd the exact time to the transition to be highly dependent on the details of the mechanisms removing heat from the thermal electron population.