In the new high-density H-mode of the W7-AS stellerator with island divertor several thermal instabilities were found. Marfes (multifaceted asymmetric radiation from the edge) were observed inboard crossing midplane. This phenomenon has much in common with the Marfe of a divertor tokamak. For some edge configurations of W7-AS, the Marfe is unstable. Simultaneously the plasma is poloidal symmetrically detached. Such a stationary poloidal symmetric detachment is already known from limiter tokamaks while the coexistent Marfe fluctuations are observed for the first time.
MARFE movement and density fluctuations after deuterium pellet injections in H-mode plasmas on EAST tokamak