Effect of 3-D fields on divertor detachment and associated pedestal profiles in NSTX H-mode plasmas

摘要

The effect of externally applied 3-D magnetic perturbations on the divertor heat and particle flux profiles has been actively studied in various tokamaks, for example in DIII-D [1] and NSTX [2,3]. These phenomena are directly related with the 'strike point (SP) splitting' caused by the 3-D magnetic field perturbations to the plasma edge [4]. As ITER is considering the use of 3-D magnetic fields for the control of ELM transient heat loads, a detailed understanding of the physical mechanism leading to the ELM suppression as well as the changes to the edge transport associated with the application of 3-D fields is necessary. Partial detachment is the divertor operation regime selected for ITER high fusion performance operation, as it allows control of heat fluxes to the divertor and erosion at the material surface during the stationary phase to values acceptable for the PEC operation lifetime. It is essential that the two schemes be compatible with each other. Thus we have investigated the effect of applied 3-D fields on the divertor detachment and its relation to the pedestal profiles in National Spherical Torus Experiment (NSTX).