Electron temperature turbulence behavior during sawtooth oscillations in DIII-D

Sawtooth oscillations are a relaxation phenomenon associated with magnetic reconnection in the central region of the plasma that are triggered by an instability near the q=1 magnetic surface. This work reports on recent experimental results of the electron temperature (T_e) turbulence behavior during sawtooth oscillations in DIII-D, measured by a radial 8-channel array correlation ECE (CECE) radiometer. The radial coverage is typically ~10-15 cm (ρ~0.2-0.3). Compared to the time right before a sawtooth crash, T_e turbulence amplitude decreases inside but increases outside the q=1 radius immediately after the crash. T_e turbulence amplitude is at the system noise level in an inner part of the magnetic reconnection region, which has a flat electron temperature profile. At the sawtooth crash, a radially outward propagation of T_e turbulence is observed. During the ramp (core temperature rising) phase of a sawtooth cycle, the T_e turbulence amplitude gradually increases until the next crash, with a larger change at inner locations that scale with the inverse T_e scale length. These observations combined with data from magnetic probes and linear stability turbulence simulations will be presented.