Speaker
Description
Runaway electrons (RE) present one of the major concerns for future fusion devices
(tokamaks), since the uncontrolled localized RE losses can compromise the integrity
of tokamak device and its further operation. Runaway electrons can emerge within a
tokamak plasma either at low density, during the discharge start-up phase or as a result of
rapid plasma termination, associated with sudden cooling causing a significant electric field
induction. In the presence of such a strong electric field, electrons can reach several tens of
MeV (kinetic energy ~ tens of MJ). The fully effective mitigation strategy was still not
identified despite the increased effort of the fusion community. Several approaches have to be
explored.
The COMPASS tokamak is an ideal device for testing such strategies and developing new
ones due to its high flexibility, advanced RE feedback, compact size and the high
reproducibility of RE scenarios. The main studied mitigation strategies are the injection of
impurities and the application of external resonant magnetic perturbations (RMPs). The
combination of mentioned mitigation strategies with emphasis on RMPs will be
examined. Conclusions about their efficiency at COMPASS will be elaborated and
basic assumptions toward larger fusion devices will be derived.
