Electron temperature and density turbulence behavior during sawtooth oscillations in DIII-D

The sawtooth instabilities in tokamaks are periodic magnetic reconnection events, where the plasma pressure profiles inside a certain plasma minor radius (the inversion radius) drop abruptly. This work reports on recent observations of the electron temperature (T_e) and density (N_e) turbulence behavior during sawtooth oscillations in a DIII-D hydrogen L-mode plasma with an inner wall limited configuration, measured by the correlation electron-cyclotron-emission (CECE) radiometer and Doppler backscattering (DBS) systems. It is observed that both T_e and N_e turbulence amplitudes vary with time during sawtooth cycles. Before each sawtooth crash, the T_e and N_e turbulence amplitudes reach a maximum level, then they show clear decrease immediately after sawtooth crash well inside the inversion radius, while no obvious change occurs near and outside the inversion radius. A critical T_e gradient behavior is found inside the inversion radius but not near or outside the inversion radius. Evidence of radial propagation of T_e turbulence is observed at the sawtooth crash. These observations combined with data from magnetic probes and linear stability turbulence simulations will be presented.