13 / 2021-04-07 17:12:36

Equilibrium effects on the structure of island divertor and its impact on the divertor heat flux distribution of W7-X

Equilibrium effects;,island divertor,heat flux,W7-X

Equilibrium effects on the structure of magnetic islands is an important and fundamental research for the usage of the 3D magnetic topology as a divertor concept, so-called island divertor, in magnetically confined fusion devices. To support a high-performance long-pulse plasma operation on W7-X with an island divertor configuration in the upcoming campaign OP2, the impact of the toroidal current and the plasma beta on the structure of island divertor and divertor power depositions have been investigated by applying the fully-3D MHD code HINT. Finite-beta (up to 5%) 3D equilibria were obtained for the four most important configurations of W7-X (“Standard”, “High-Iota”, “Low-Iota”, and “High-Mirror”). The configurations were seen to have varying degrees of edge stochastization responding to finite beta, except for low-iota configuration with a reduction of the island widths and an eventual transition to a limiter-like edge topology. Moreover, a positive scaling of the wetted area with increasing plasma beta was demonstrated from both the simulation and experiment results, which is beneficial for high-performance long-pulse plasma operation.