Internal Magnetic Turbulence Measurement in Plasma by Cross Polarization Scattering

For the first time, the internal magnetic turbulence is measured by a new cross polarization scattering diagnostic in the Tore Supra tokamak. The principle of this experiment is presented. It is based on the polarization change or mode conversion of the electromagnetic wave scattered by magnetic fluctuations. A strong correlation between the internal magnetic fluctuation and the additional heating is observed, contrary to the edge fluctuations. The observed fluctuations increase linearly with the poloidal beta number βₚ in the L-mode confinement regime.