抄録
In this study, the effects of resonant magnetic perturbation (RMP) on particle transport are investigated in Large Helical device (LHD). The magnetic configuration is selected to be the outwardly shifted configuration, for which the magnetic axis position (Rax) is 3.9 m. At Rax = 3.9 m, the main plasma is surrounded by a thick ergodic layer, with width of about 30% of the plasma minor radius. The perturbation mode m/n = 1/1, where m and n are poloidal and toroidal mode numbers, is applied. The resonant layer is around the last closed flux surface. With RMP, a region in which both the connection and Kolmogorov lengths are finite and the magnetic field is ergodic forms; this region extends inside the main plasma. In the low-collisionality regime, where νh∗< 1(νh∗= 1 is the boundary between the 1/ν and plateau regimes in stellarator/helical neoclassical transport), there is no apparent difference in particle transport with and without RMP. However, in the high-collisionality regime (νh∗ > 1), a clear difference in particle transport is found. A clear difference in turbulence is also observed, suggesting that turbulence plays a significant role in particle transport in the high-collisionality regime both with and without RMP.
