Recent Results of Heliotron–E Experiment

Recent results of Heliotron E experiment are reviewed. Detailed studies of the plasma transport have been achieved in Heliotron E, in which the plasma wall interaction has been changed using the ECH boronization technique. The boronization realized low-density, high-T_i plasmas whose ion collisionality deeply extended to the I/v-regime. The local electron and ion thermal diffusivities in the NBI plasma are analyzed and discussed by comparison with theory-based transport models. The particle transport in ECH plasmas is investigated with edge fluctuation measurements. Both electrostatic and magnetic fluctuations are well correlated with the global particle confinement. Characteristic structures of the electric field or potential distribution are observed during the particle confinement degradation phase. It is considered that dc convective flow across the last closed flux surface is caused by the potential structure. Edge plasma flows have been discussed in connection with these studies and with asymmetric divertor heat/particle load.