Abstract
First results are reported from the 3D Monte Carlo far-SOL impurity transport code 3DLIM. Tungsten deposition profiles measured on a Collector Probe (CP) located in the far-SOL near the outer midplane, OMP, during W tracer experiments in DIII-D are reproduced by 3DLIM. Radial deposition profiles are replicated showing the effect that a decrease in connection length from the CP to the nearest wall contact point has on impurity transport to the probe, as well as the effect of assuming purely diffusive vs convective radial transport. For purely diffusive radial transport, a diffusion coefficient of 10 m2/s best reproduces deposition patterns on both sides of the CP, but for purely convective radial transport a speed of 125 m/s is shown to have better agreement with the ITF deposition profile. Deposition profiles show peaking in W content along the length of the CP edges that is also reproduced in 3DLIM, but only when assuming a convection-dominated SOL plasma parallel transport prescription for the background plasma. The degree of the peaking is shown to be a secondary indicator of the effective location of the W source in the near-SOL OMP relative to the far-SOL (near/far from the separatrix). Identifying the location of the effective source provides insight into near-SOL impurity dynamics, including the existence and location of impurity accumulation near the OMP separatrix. Such accumulation typically occurs in SOLPS and other edge code modeling, but has hitherto been difficult to confirm experimentally. The impurity density at the edge is the boundary condition for impurity levels in the confined plasma.
Original language | English |
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Article number | 100811 |
Journal | Nuclear Materials and Energy |
Volume | 25 |
DOIs | |
State | Published - Dec 2020 |
Funding
The author would like to thank Andreas Wingen for providing them with connection length data from the MAFOT code. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, using the DIII-D National Fusion Facility, a DOE Office of Science user facility, under Awards DE-FC02-04ER54698, DE-SC0016318 and DE-SC0019256. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. The author would like to thank Andreas Wingen for providing them with connection length data from the MAFOT code. This material is based upon work supported by the U.S. Department of Energy , Office of Science, Office of Fusion Energy Sciences, using the DIII-D National Fusion Facility, a DOE Office of Science user facility, under Awards DE-FC02-04ER54698, DE-SC0016318 and DE-SC0019256.
Keywords
- 3DLIM
- Collector Probes
- DIII-D
- Far-SOL
- Impurity transport
- Metal Rings Campaign