Measurement of magnetic fluctuations of electromagnetic plasma waves by cross-polarization scattering

The cross-polarization scattering (CPS) technique was applied to the GAMMA 10 tandem mirror for measurements of internal magnetic fluctuations associated with waves in the ion cyclotron range of frequency. The CPS is related to the mode-conversion effect consisting of a polarization difference of a scattered wave with regard to an incident wave. In GAMMA 10, the incident ordinary (extraordinary) wave is transferred to the extraordinary (ordinary) wave by magnetic field fluctuations near the cutoff layer of a plasma. The transferred wave penetrates through the cutoff layer and is detected. The frequency spectra and density and magnetic field fluctuations of the waves are evaluated from the CPS diagnostic and reflectometry. The ratio of the magnetic field to density fluctuation level depends on the phase velocity of the slow Alfvacute en wave. The CPS data are also compared with those obtained from magnetic probes. copyright 1997 American Institute of Physics