Erosion, transport, and tritium codeposition analysis of a beryllium wall tokamak

Jeffrey N. Brooks, Jean Paul Allain, Darren A. Alman, David N Ruzic

Research output: Contribution to journalArticlepeer-review

Abstract

We analyzed beryllium first wall sputtering erosion, sputtered material transport, and T/Be codeposition for a typical next-generation tokamak design - the fusion ignition research experiment (FIRE). The results should be broadly applicable to any future tokamak with a beryllium first wall. Starting with a fluid code scrapeoff layer attached plasma solution, plasma D0 neutral fluxes to the wall and divertor are obtained from the DEGAS2 neutral transport code. The D+ ion flux to the wall is computed using both a diffusive term and a simple convective transport model. Sputtering coefficients for the beryllium wall are given by the VFTRIM-3D binary-collision code. Transport of beryllium to the divertor, plasma, and back to the wall is calculated with the WBC+ code, which tracks sputtered atom ionization and subsequent ion transport along the SOL magnetic field lines. Then, using results from a study of Be/W mixing/sputtering on the divertor, and using REDEP/WBC impurity transport code results, we estimate the divertor surface response. Finally, we compute tritium codeposition rates in Be growth regions on the wall and divertor for D-T plasma shots using surface temperature dependent D-T/Be rates and with different assumed oxygen contents. Key results are: (1) peak wall net erosion rates vary from about 0.3 nm s-1 for diffusion-only transport to 3 nm s-1 for diffusion plus convection, (2) T/Be codeposition rates vary from about 0.1 to 10.0 mg T s-1 depending on the model, and (3) core plasma contamination from wall-sputtered beryllium is low in all cases (< 0.02%). Thus, based on the erosion and codeposition results, the performance of a beryllium first wall is very dependent on the plasma response, and varies from acceptable to unacceptable.

Original languageEnglish (US)
Pages (from-to)363-375
Number of pages13
JournalFusion Engineering and Design
Volume72
Issue number4
DOIs
StatePublished - Jan 2005

Keywords

  • Beryllium
  • Tokamak
  • Tritium codeposition

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Mechanical Engineering

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