Events at Physics
Helium exhaust is the most generic task for a divertor in magnetically confined fusion plasmas. Without sufficient helium exhaust, it will not be possible to maintain a burning plasma. Measurements and modeling results are presented which demonstrate that resonant magnetic perturbations can be used to improve the helium exhaust features. We compare the dynamic ergodic divertor at the TEXTOR tokamak with the helical divertor in the LHD heliotron. It is shown that a magnetic island in the very plasma edge can be used on both devices as a fine actuator on the helium and main plasma confinement characteristics. Modeling with the EMC3-EIRENE plasma fluid and kinetic neutral transport code supports that the most critical part of the challenge is condensation of the helium which recycles many times on the surfaces outside of the confined volume and close to the exhaust devices is important to generate efficient helium exhaust. The combination of results from modeling and experiment provide consistent evidence that a combination of enhanced outward helium transport with improved coupling to the exhaust devices due to the edge magnetic island induced can yield a substantially enhanced overall helium exhaust.