On the effects of magnetic perturbations on fast ion losses studied at TEXTOR

One criterion for the ignition of a fusion plasma is sufficient fast ion confinement. A key aspect in that context is the maintainability of good fast ion confinement in the presence of non-axisymmetric fields, such as those found in stellarators and during the application of resonant magnetic perturbations (RMPs) in tokamaks. This paper focuses on the influence of RMPs on the fast ion losses, studied at the Tokamak experiment for technology-oriented research (TEXTOR), a medium-sized device. TEXTOR is equipped with a flexible perturbation coil system, the dynamic ergodic divertor, allowing for the application of static or rotating perturbation fields. A rotating directional probe is used for the radially resolved fast ion loss measurements. The results achieved are presented and discussed for the poloidal/toroidal perturbation modes m/n = 3/1 and 6/2, with static and rotating fields.