FIELD REVERSAL EFFECTS ON PARTICLE AND HEAT FLUXES IN DIVERTOR ON JT-60U

The directions of both the toroidal field and the plasma current are reversed (ion del B drift direction away from the divertor target) in order to reduce an asymmetry of the heat flux distribution at the divertor plates during L-mode discharges on JT-60U. The profiles of electron temperature and density at the divertor target are found to be more symmetric for the reversed field. Reversing the held, particle and impurity recycling is changed from an inboard-enhanced to an outboard-enhanced one, whereby the global particle confinement time remains the same. A symmetric heat load profile changes to an outboard-dominated one with increasing density (n) over bar(e) and safety factor q(eff) of the main plasma for the ion del B drift direction towards the X-point. While an inboard-dominated heat load profile changes to a symmetric one when the ion del B drift direction is away from the X-point. This redistribution of the heat load profile to the divertor target is not explained by the contribution of the radiation loss to the total power balance.