Long-wavelength (k(perpendicular-to)rho(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 fluctu
ations of n/n > 0.5% exist for k(perpendicular-to) < 2 cm-1 with radia
l and poloidal correlation lengths typically 1-2.5 cm in the confineme
nt region, corresponding to k(perpendicular-to)rho(i) almost-equal-to
0.1-0.3. An anisotropic wave-number spectrum is observed, and estimate
s of the turbulence-driven transport are comparable to the anomalous t
ransport observed in tokamaks.