Sawtooth Crash Modifications to Intermediate-k Turbulence and Flows on DIII-D

Initial data from the new multichannel Doppler backscattering and reflectometry diagnostic system on DIII-D are presented including results showing increased intermediate-$k$ ($k_\perp \rho_s \sim 2$, $k_\perp \sim$ 6-7 cm$^{-1}$) density fluctuations and flow velocity modifications associated with the sawtooth crash. In Ohmic plasmas at radial location $\rho \stackrel{\sim}{=} 0.4$, density fluctuation propagation velocity excursions of up to $\sim$9 km/s from an equilibrium of \hbox{$\sim0 $ km/s} and relaxation back to equilibrium in less than 200 $\mu$s are observed. Density fluctuation levels are observed to increase within the same period and to remain at a higher level for an additional 200-500 $\mu$s. Details and capabilities of the new multichannel (currently 4-channel) system for simultaneous multipoint measurements with frequencies separated by 350 MHz and tunable in the range 53-78 GHz are described.