Study of the Absorption Rate of Lower Hybrid Wave Energy by High Energetic Ions in Tokamak

Abstract

Lower hybrid driven current has been proven to be the most efficient way to drive current in tokamak, and it will be applied in ITER. However high energetic ions generated by fusion reactions, injection of neutral beams, and RF acceleration can absorb lower hybrid wave (LHW) reducing the CD efficiency. The absorption rates of three kinds of high energetic ions to LHW under ITER’s parameters are studied for comparison in the paper. The absorption rate of protons with 1 MeV is almost the same level as that of alpha particles, but the absorption rate of deuterons is lower than those of protons and alpha particles. Generally the absorption rate increases with the parallel refractive index as well as the toroidal magnetic field, and increases with the LHW frequency and then decreases with it. The background plasma temperature has little influence on the absorption rate, but it increases fast at first and then descends slightly with the background plasma density.