Scrape-off layer transport and deposition studies in DIII-D

Research output: Contribution to journalArticle

Researchers

  • Mathias Groth

  • S. L. Allen
  • J. A. Boedo
  • N. H. Brooks
  • J. D. Elder
  • M. E. Fenstermacher
  • R. J. Groebner
  • C. J. Lasnier
  • A. G. McLean
  • A. W. Leonard
  • S. Lisgo
  • G. D. Porter
  • M. E. Rensink
  • T. D. Rognlien
  • D. L. Rudakov
  • P. C. Stangeby
  • W. R. Wampler
  • J. G. Watkins
  • W. P. West
  • D. G. Whyte

Research units

  • Lawrence Livermore National Laboratory
  • University of California at San Diego
  • General Atomics
  • University of Toronto
  • Sandia National Laboratories
  • Massachusetts Institute of Technology

Abstract

Trace C13 H4 injection experiments into the main scrape-off layer (SOL) of low density L-mode and high-density H-mode plasmas have been performed in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] to mimic the transport and deposition of carbon arising from a main chamber sputtering source. These experiments indicated entrainment of the injected carbon in plasma flow in the main SOL, and transport toward the inner divertor. Ex situ surface analysis showed enhanced C13 surface concentration at the corner formed by the divertor floor and the angled target plate of the inner divertor in L-mode; in H-mode high surface concentration was found both at the corner and along the surface bounding the private flux region inboard of the outer strike point. Interpretative modeling was made consistent with these experimental results by imposing a parallel carbon ion flow in the main SOL toward the inner target, and a radial pinch toward the separatrix. Predictive modeling carried out to better understand the underlying plasma transport processes suggests that the deuterium flow in the main SOL is related to the degree of detachment of the inner divertor leg. These simulations show that carbon ions are entrained with the deuteron flow in the main SOL via frictional coupling, but higher charge-state carbon ions may be suspended upstream of the inner divertor X-point region due to balance of the friction force and the ion temperature gradient force.

Details

Original languageEnglish
Article number056120
Pages (from-to)1-13
Number of pages13
JournalPhysics of Plasmas
Volume14
Issue number5
Publication statusPublished - 2007
MoE publication typeA1 Journal article-refereed

ID: 4079152