Study of Efficient Electron Cyclotron Wave Coupling with Grooved Mirror Polarizer in the GAMMA 10 Tandem Mirror

An improvement of electron cyclotron heating (ECH) system in the central cell of the GAMMA 10 tandem mirror is carried out by the use of two grooved mirrors. Two grooved mirrors consist of a twister and a circular polarizer. In case of the ECH system in the central cell region, fundamental ECH is examined and launched microwave beam from the antenna propagates through the two parabolic mirrors. The incident microwave is radiated from the second mirror at a position with magnetic field intensity B=2.0 T and with an incident angle of 35.1 degrees. Two grooved mirrors can generate suitable elliptical polarizations for both of ordinary mode (O-mode) and extraordinary mode (X-mode) in oblique launch with a slanted magnetic field line. The first results of the polarization control of the incident wave for high power ECH experiments are reported.