Long-wavelength density turbulence in the TFTR tokamak

Long-wavelength (${\mathit{k}}_{\mathrm{\ensuremath{\perp}}}$${\mathrm{\ensuremath{\rho}}}_{\mathit{i}}$1) density turbulence has been measured with good spatial localization in the core region of a high temperature tokamak plasma with auxiliary heating. Density fluctuations of n\ifmmode \tilde{}\else \~{}\fi{}/n>0.5% exist for ${\mathit{k}}_{\mathrm{\ensuremath{\perp}}}$2 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ with radial and poloidal correlation lengths typically 1--2.5 cm in the confinement region, corresponding to ${\mathit{k}}_{\mathrm{\ensuremath{\perp}}}$${\mathrm{\ensuremath{\rho}}}_{\mathit{i}}$\ensuremath{\approxeq}0.1--0.3. An anisotropic wave-number spectrum is observed, and estimates of the turbulence-driven transport are comparable to the anomalous transport observed in tokamaks.