Multichannel Scattering Studies of the Spectra and Spatial Distribution of Tokamak Microturbulence

Detailed studies of low-frequency microturbulence are presented. We utilize a unique multi-channel far-infrared ($\lambda =1.22\mathrm{}$ mm) laser scattering system capable of measuring the entire $S(k_{\perp }, \omega )$ spectrum during a single tokamak discharge. A statistical dispersion is unfolded for $k_{\theta }$ which exhibits a phase velocity $\simeq 3v_{\mathrm{De}}$ at low $k_{\theta }$ with a distinct rolloff for $k_{\theta }>~9$ ${\mathrm{cm}}^{-1\mathrm{}}$. In addition, a strong spatial asymmetry is observed in the $k_{\theta }$ density-fluctuation distribution which reverses with toroidal current direction.