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 ($\ensuremath{\lambda}=1.22$ mm) laser scattering system capable of measuring the entire $S({k}_{\ensuremath{\perp}}, \ensuremath{\omega})$ spectrum during a single tokamak discharge. A statistical dispersion is unfolded for ${k}_{\ensuremath{\theta}}$ which exhibits a phase velocity $\ensuremath{\simeq}3{v}_{\mathrm{De}}$ at low ${k}_{\ensuremath{\theta}}$ with a distinct rolloff for ${k}_{\ensuremath{\theta}}>~9$ ${\mathrm{cm}}^{\ensuremath{-}1}$. In addition, a strong spatial asymmetry is observed in the ${k}_{\ensuremath{\theta}}$ density-fluctuation distribution which reverses with toroidal current direction.