Doppler Reflectometer System for Measuring Rotation Velocity of Fluctuation in GAMMA 10

摘要

Doppler reflectometry is currently used as a powerful technique to measure the perpendicular (to the magnetic field) velocity of density fluctuation, the radial electric field, and the perpendicular wave number spectrum in many fusion plasma devices. In GAMMA 10 a Doppler reflectometer has recently been installed to measure perpendicular rotation velocity of density fluctuation in the cylindrical plasma. The Doppler reflectometer has an antenna system with a launching/receiving scalar feed antenna and focusing mirrors. By rotating one of the mirrors the tilt angle of the incident microwave can be controlled against the normal of cutoff layers. A frequency synthesizer is used in the range 11.5 - 18 GHz as the stable microwave source of X-mode probing beam for GAMMA 10 plasma having typical peak density ∼2 × 1018 m−3. The first preliminary results of Doppler shifted spectra and radial profiles of the perpendicular velocity of density fluctuations are presented for ICRF start-up plasma with additional ECH. The rotation of fluctuations during additional ECH period is found to become opposite direction comparing to the case of ICRF heating alone.