MEASUREMENT OF ICRF WAVES IN THE GAMMA10 TANDEM MIRROR USING REFLECTOMETERS

Microwave reflectometry has been applied to the central cell of the GAMMA 10 tandem mirror for measurements of fluctuations in the ion cyclotron range of frequency (ICRF). The instability with frequency ω<ωci is identified as the Alfvén ion cyclotron wave driven by plasma β and ion pressure anisotropy. Internal magnetic fluctuations with δB/B∼10-4 as well as density fluctuations of the same level for this wave are determined by a combination of X- and O-mode reflectometers. The fluctuations associated with the ICRF heating wave (ω= ωci) are also observed by three separated X/O mode reflectometers to study the physics of wave excitation and propagation. The radial profile of the fluctuation level is expected to give an estimation of the deposition profile of the heating power. The results will be applied in order to achieve efficient ion heating and to help the power balance study of central-cell plasma. © 1995 American Institute of Physics.