Runaway electron losses enhanced by resonant magnetic perturbations

• Disruptions in large tokamaks can lead to the generation of a relativistic runaway electronbeam that may cause serious damage to the first wall. To suppress the runaway beam the applicationof resonant magnetic perturbations (RMP) has been suggested. In this work we investigate the effect ofresonant magnetic perturbations on the confinement of runaway electrons by simulating their drift orbitsin magnetostatic perturbed fields and calculating the transport and orbit losses for various initial energiesand different magnetic perturbation configurations. In the simulations we use model configurations withexisting (TEXTOR) and planned (ITER) RMP systems, and solve the relativistic, gyro-averaged driftequations for the runaway electrons including the electric field, radiation losses and collisions. The resultsindicate that runaway electrons are well confined in the core of the device, but the onset time of runawaylosses closer to the edge is dependent on the magnetic perturbation level, which can thereby affectthe maximum runaway current. Runaway electrons are rapidly lost from regions where the normalisedperturbation amplitude \delta B/B is larger than 0.1% in a properly chosen perturbation geometry. Thisapplies to the region outside the radius corresponding to the normalised flux \psi = 0.5 in ITER, when theELM mitigation coils are used at maximum current in their most favourable configuration.

Ämnesord

NATURVETENSKAP  -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)

Publikations- och innehållstyp

kon (ämneskategori)

ref (ämneskategori)