Elsevier

Nuclear Materials and Energy

Volume 19, May 2019, Pages 358-363
Nuclear Materials and Energy

Use of isotopic tungsten tracers and a stable-isotope-mixing model to characterize divertor source location in the DIII-D metal rings campaign

https://doi.org/10.1016/j.nme.2019.02.028Get rights and content
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Highlights

  • A basic model is presented that aided the first-time use of isotopic W tracers in a fusion device.

  • Using the model, upstream probe deposition shows that the W sources follow strike-point position.

  • Isotopic signatures have asymmetric deposition patterns on opposite sides of the upstream probe.

Abstract

A basic stable isotope mixing model (bSIMM) is presented that enables the first-time use of multiple isotopic tungsten (W) tracers in a fusion device. DIII-D installed two toroidally symmetric, but poloidally distinct, arrays of tiles in the outer region of the lower divertor that are each distinguishable by different stable-isotope signatures of W. This installation was called the metal rings campaign. Experiments were then carried out with this setup to assess the W source from each location and how the sourced W led to contamination of the main scrape-off layer (SOL). The bSIMM method is derived and shown to be in good agreement with benchmark tests using known mixtures of different isotopic W signatures. The method is applied to a set of dual-facing impurity Collector Probes (CP) exposed in H-mode discharges during this metal rings campaign. Using the bSIMM as the main analysis tool, CP radial profiles show that the divertor W sources follow the discharge's strike-point position. In addition, opposing faces of the CPs have different W deposition profiles indicating poloidal variation of W content in the SOL and the isotopic signatures are shown to follow these trends. This work demonstrates that this methodology for detecting isotopic W sourced from different plasma facing components in a fusion device is reliable and versatile.

Keywords

Tungsten
Plasma-facing materials
Isotope tracers
DIII-D

Cited by (0)

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-NA0003525, DE-AC05-00OR22725, and DE-AC52-07NA27344. DIII-D data shown in this paper can be obtained in digital format by following the links at https://fusion.gat.com/global/D3D_DMP.