Beam emission spectroscopy diagnosis of turbulence in high temperature tokamak plasmas

Summary form only given. Beam emission spectroscopy (BES) is a diagnostic technique which provides localized measurements of density turbulence in high-temperature magnetically confined plasmas. BES detects local plasma fluctuations by observing intensity fluctuations in collisionally induced neutral beam fluorescence from a diagnostic beam injected into the hot plasma. With this approach it is possible to access the wavelength region of peak fluctuation amplitude in the plasma, and new features of the turbulence spectrum have emerged. For example, a strong anisotropy is observed in the wavenumber spectra perpendicular to the local field, where the radial spectrum peaks at k/sub 4/ = 0 cm/sup -1/, while the poloidal spectrum peaks at k/sup /spl theta/spl ap/ 1 cm/sup -1/. Estimates of turbulence-driven fluxes indicate that the observed fluctuations are sufficient to driven the observed anomalous cross-field transport in tokamak plasmas with strong auxiliary heating.