Fluctuation measurements in the plasma interior on TFTR

New beam emission spectroscopy and correlation reflectometry density fluctuation diagnostics on TFTR allow examination of the crucial long wavelength (k_{perpendicular to} rho _i<0.1) region, where microwave scattering has indicated where the bulk of the power density lies. The turbulent spectrum for low k is broadband and dominated by low frequencies (<200 KHz), and the exact nature of the spectrum is dominated by Doppler effects. These core diagnostics show n/n rising as tau _E decreases. Radial and poloidal correlation lengths from BES are comparable and are roughly 2-3 cm near the plasma edge and gradually drop to 1-2 cm in the region of r/a=0.5-0.7. Values <1.5 cm are indicated deeper in the core region, but precise values await further analysis which takes into account the effects of finite spatial resolution of the BES measurements. A strong anisotropy in the radial and poloidal wavenumber spectra is indicated from the shape of the correlation functions. The poloidal wavenumber spectrum does not increase indefinitely as k goes to 0 cm^-1, but has a peak in the range of 1-2 cm^-1.