The combined impact of the main ion isotope and wall material on divertor conditions

Using either carbon or tungsten as a first wall material has been demonstrated to have significant influence on divertor conditions through changes to impurity influx from sputtering and recycling coefficients. The isotope of the main ion has similar influence on this region, motivating a combined study of these factors with edge fluid modeling to determine the net effects of a change in wall material and isotope. SOLPS-ITER modeling is used to investigate changes to both detachment and fueling in hydrogen, deuterium, and tritium plasmas with carbon and tungsten first walls. Under attached and high-recycling conditions the wall material is demonstrated to have the primary impact on divertor conditions, resulting in a higher target density with a tungsten first wall, while there is a relatively small contribution of less than 10% resulting from the change in isotope. However, in detached conditions, the different recycling properties between isotopes becomes more consequential and may be equally as important as the wall material change, as long as T_e is above the fast reflection cutoff energy.



Acknowledgements

This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, under award(s) DE-SC0023100, DE-FC02-04ER54698, DE-FC02-4500093207, and DE-AC52-07NA27344.