Multi-scale, Multi-field Turbulence Response During Electron Cyclotron Heating (ECH)

ECH at $r/a \sim 0.4$ significantly modifies the electron temperature of LSN Ohmic plasmas with minimal effect on local ion temperature and electron density. A unique array of turbulence diagnostics was used to study the turbulence response across all turbulent scales ($0 < k\rho_s < 10$) and for two distinct turbulent fields. At $r/a \sim 0.6$, low-$k$ electron temperature fluctuations increased significantly ($\sim 3$) with ECH. In contrast, low and intermediate-$k$ density fluctuations remained unchanged or reduced slightly. High-$k$ ($\sim$35 cm$^{-1}$) density fluctuations, associated with the electron temperature gradient driven mode, increased by $>$30\%. Interestingly, low-$k$ density and electron temperature fluctuations were found to be locally correlated across the frequency range $\sim$10-100 kHz. This unique data set can be utilized to rigorously test the turbulence physics inherent in nonlinear gyrokinetic turbulence codes.