Investigation of Direct Momentum Transfer from the RF Waves to the Plasmas when the Mode Conversion Occurs

摘要

Mode conversion have been observed in multi-ion species ICRF heating near a resonance in Alcator C-Mod tokamak[1] and also in JET[2]. Recently, one of the most potentially important effect of mode converted heating, the toroidal flow generation, has been observed in both of C-Mod and JET and compared the results with each other.[3] They reported the weak dependence of the flow on antenna current phase and implicated that the momentum is not coming from the wave itself. But the more recent experimental results of Alcator C-Mod[4] shows that as increase RF power, the flow is affected by the antenna current phase. We calculate the Maxwell stress tensor of the ICRF wave to investigate the direct momentum transfer from waves. The resulting forces exerted on the plasmas are quite impressive. The net poloidal force is almost negligible on the other hand the toroidal force is noticeably strong. The toroidal force is proportional to the RF power and the direction strictly depends on the antenna current phase.