Reflectometric measurement of density and magnetic fluctuations in CRF-driven waves

Reflectometric techniques have been applied to the GAMMA 10 tandem mirror to measure density and magnetic fluctuations associated with electromagnetic plasma waves in the ion cyclotron range of frequency (ICRF). The excitation and propagation of ICRF-driven waves are studied by reflectometers in order to achieve efficient heating of plasmas. The radial profile of the fluctuation level is expected to give the deposition profile of the heating power. A cross-polarization scattering diagnostic system is also installed in the central cell of GAMMA 10. An incident ordinary (extraordinary) wave is converted to an extraordinary (ordinary) wave by magnetic fluctuations. The converted wave can propagate through a cut-off layer and reach the detector. The level of magnetic fluctuation (about 10−4) is evaluated for the ICRF-driven waves.