The Research Of Lower Hybrid Current Drive System

Lower hybrid current drive (LHCD) is one of the most important non-inductive heating methods in Tokamak experiment and its basic research has been done in this paper. The purpose of constructing LHCD is to maintain the plasma current continuously so that the Tokamak machine can be operated with long impulse under the steady-state condition. This plays a vital role to the realization of fusion reaction.LHCD system consists of microwave antenna, waveguide transmission line, vacuum vessel and microwave source. The waveguide transmission line is introduced in detail and its mechanics analysis is done. The waveguides structure composed of two different materials is proposed to keep a reliable structure. Also, this structure can remove the RF loss and reduce eddy currents. The antenna is the critical part of the LHCD system. Its structure is very complicated and this brings a lot of difficulties to the design, manufacturing and assembly. The water cooling way is used to remove the RF loss in the waveguide. Such a system has been demonstrated to have a very good power handling capability.This system will be one of the longest impulse and large power LHCD in the world after it is finished. It will be used to maintain the plasma current during the next HT-7U experiment.