Magnetic configuration effects on the edge heat flux in the limiter plasma on W7-X measured using the infrared camera and the combined probe

• Published in: Plasma science & technology 2018-05, Vol.20 (5), p.54003
• Main Authors: DREWS, P, NIEMANN, H, COSFELD, J, GAO, Y, GEIGER, J, GRULKE, O, HENKEL, M, HÖSCHEN, D, HOLLFELD, K, KILLER, C, KRÄMER-FLECKEN, A, LIANG, Y, LIU, S, NICOLAI, D, NEUBAUER, O, RACK, M, SCHWEER, B, SATHEESWARAN, G, RUDISCHHAUSER, L, SANDRI, N, WANG, N
• Format: Article
• Language: English
• Subjects: heat flux; limiter; plasma edge; W7-X; Wendelstein 7-X
• ISSN: 1009-0630; 1009-0630
• DOI: 10.1088/2058-6272/aaa968

Controlling the heat and particle fluxes in the plasma edge and on the plasma facing components is important for the safe and effective operation of every magnetically confined fusion device. This was attempted on Wendelstein 7-X in the first operational campaign, with the modification of the magnetic configuration by use of the trim coils and tuning the field coil currents, commonly named iota scan. Ideally, the heat loads on the five limiters are equal. However, they differ between each limiter and are non-uniform, due to the (relatively small) error fields caused by the misalignment of components. It is therefore necessary to study the influence of the configuration changes on the transport of heat and particles in the plasma edge caused by the application of error fields and the change of the magnetic configuration. In this paper the up-stream measurements conducted with the combined probe are compared to the downstream measurements with the DIAS infrared camera on the limiter.