Overview of Recent DIII-D Experimental Results

DIII-D experiments advance scientific understanding for ITER and future tokamak fusion reactors. Intrinsically non-ELMing enhanced confinement regimes exhibit steady operation and high confinement while avoiding ELMs and associated material erosion. Control of ELMs using resonant magnetic perturbations achieved record pedestal pressures. Simultaneous RMP ELM mitigation and divertor detachment have been achieved in the DIII-D ITER-similar shape plasma. Charge exchange measurements for typical pedestals and show good agreement with synthetic spectra from neutral transport modeling. Edge ionization source measurements for dimensionally matched hydrogen and deuterium H-mode pedestals show a clear isotope-mass effect. Decreased carbon impurity content is identified as the dominant isotope effect responsible for increasing the L-H power threshold in hydrogen at low collisionality. Rotation profile hollowing is identified as an important cause of the majority of disruptive m,n=2,1 tearing mode onsets in low-torque ITER plasmas. Modeling of argon pellet ablation agrees with experiment and validates pellet-based disruption mitigation. Ion cyclotron emission spatial mode structure has been characterized for the first time. Agreement is found between modeled and measured density fluctuation wavenumber spectra in low collisionality H-mode plasmas.