Effect of Resonant Magnetic Perturbations (RMPs) on Local Density Decay During Pellet Injection in DIII-D

By using a high temporal (25 microseconds) and spatial ($\sim$0.5~cm) resolution profile reflectometer system, the local density evolution due to deuterium pellet injection has been investigated in \mbox{DIII-D}. It is observed that either no ELMs are triggered, or small ELMs are triggered by fueling pellets during ELM suppressed RMP operation. However, $\sim$150~ms after the pellet injection the plasma returns to ELM-free status. The density evolution shows local density decay time is a decreasing function of radius, with the fastest decay at around normalized $\psi \sim\,$0.92 which is within the magnetic island overlap regime. By contrast, pellet induced local density decay time is almost independent of radius for non-RMP ELMing plasmas, with the decay time 2 times longer than with RMPs. The results suggest RMPs enhance particle transport in plasmas. The dependence of local decay time on the magnitude of RMPs, associated density fluctuations, and $E_r$ behavior are further investigated.