Abstract
An experimental study of migration of tungsten in the DIII-D divertor is described, in which the outer strike point of L-mode plasmas was positioned on a toroidal ring of tungsten-coated metal inserts. Net deposition of tungsten on the divertor just outside the strike point was measured on graphite samples exposed to various plasma durations using the divertor materials evaluation system. Tungsten coverage, measured by Rutherford backscattering spectroscopy (RBS), was found to be low and nearly independent of both radius and exposure time closer to the strike point, whereas farther from the strike point the W coverage was much larger and increased with exposure time. Depth profiles from RBS show this was due to accumulation of thicker mixedmaterial deposits farther from the strike point where the plasma temperature is lower. These results are consistent with a low near-surface steady-state coverage on graphite undergoing net erosion, and continuing accumulation in regions of net deposition. This experiment provides data needed to validate, and further improve computational simulations of erosion and deposition of material on plasma-facing components and transport of impurities in magnetic fusion devices. Such simulations are underway and will be reported later.
| Original language | English |
|---|---|
| Article number | 014041 |
| Journal | Physica Scripta |
| Volume | 2017 |
| Issue number | T170 |
| DOIs | |
| State | Published - Dec 1 2017 |
| Event | 16th International Conference on Plasma-Facing Materials and Components for Fusion Applications, PFMC 2017 - Neuss/Dusseldorf, Germany Duration: May 16 2017 → May 19 2017 |
Funding
This work was supported by the United States Department of Energy Office of Fusion Energy Science under contracts DENA0003525, DE-FC02-04ER54698 and DE-AC52-07NA27344. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the US Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. This work was supported by the United States Department of Energy Office of Fusion Energy Science under contracts DE- NA0003525, DE-FC02-04ER54698 and DE-AC52-07NA27344. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the US Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Keywords
- DIII-D
- Material erosion and deposition
- Plasma-material interactions
