Speaker
Description
See full abstract here
http://ocs.ciemat.es/EPS2019ABS/pdf/P2.1075.pdf
Measurements of main-ion (D+) properties from the pedestal top to separatrix are challenging the commonly held assumption that the impurity toroidal rotation and temperature always provides a good proxy for the main-ion properties near the plasma edge. This has far-reaching consequences for SOL boundary conditions, pedestal stability, edge turbulence, momentum transport, and intrinsic rotation. Differences in the main-ion toroidal rotation include the absence of a commonly observed notch feature in the impurity toroidal rotation and the presence of a rapid co-current rotation near the separatrix which can reach values up to 100km/s for low collisionality QH-modes. This rotation is in agreement with ion orbit loss and global drift-kinetic calculations (XGC0) providing a clear demonstration of the importance of finite orbit width effects near the plasma edge and their possible role in intrinsic rotation generation.
The D+ temperature can be half the C6+ temperature at the separatrix in H-mode resolving the mystery of anomalously high and sometimes inverted ion temperature profiles inferred from impurities near the plasma edge. The difference in the ion temperatures is contrary to expectations given the rapid equilibration time between ion species and is thought to be due to a combination of non-local effects (presence of higher energy thermal tail ions from higher up the pedestal) and atomic physics processes near the plasma edge which act as an energy sink for D+ and a particle sink for C6+. In many cases using the main ion temperature profiles resolves issues with physically implausible negative ion heat fluxes which have long hindered energy transport studies in the pedestal region along with modifying the calculated drive for micro-instabilities which play a role in setting the pedestal structure.
Work supported by US DOE under DE-FC02-04ER54698 and DE-AC02-09CH11466.
