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Title: Advances in understanding of high- Z material erosion and re-deposition in low- Z wall environment in DIII-D

Dedicated DIII-D experiments coupled with modeling reveal that the net erosion rate of high-Z materials, i.e. Mo and W, is strongly affected by carbon concentration in the plasma and the magnetic pre-sheath properties. We have investigated different methods such as electrical biasing and local gas injection to control high-Z material erosion. The net erosion rate of high-Z materials is significantly reduced due to the high local re-deposition ratio. The ERO modeling shows that the local re-deposition ratio is mainly controlled by the electric field and plasma density within the magnetic pre-sheath. The net erosion can be significantly suppressed by reducing the sheath potential drop. A high carbon impurity concentration in the background plasma is also found to reduce the net erosion rate of high-Z materials. Both DIII-D experiments and modeling show that local 13CH 4 injection can create a carbon coating on the metal surface. The profile of 13C deposition provides quantitative information on radial transport due to E × B drift and the cross-field diffusion. The deuterium gas injection upstream of the W sample can reduce W net erosion rate by plasma perturbation. The inter-ELM W erosion we measured in H-mode plasmas, rates at different radial locations are wellmore » reproduced by ERO modeling taking into account charge-state-resolved carbon ion flux in the background plasma calculated using the OEDGE code.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [2] ;  [5] ;  [5] ;  [3] ;  [5] ;  [8] ;  [6] ;  [9] ;  [5] ;  [9] ;  [9] ;  [5] ;  [5] more »;  [10] ;  [7] ;  [8] ;  [4] « less
  1. Oak Ridge Associated Univ., Oak Ridge, TN (United States); Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Plasma Physics; General Atomics, San Diego, CA (United States)
  2. Univ. of California, San Diego, CA (United States)
  3. Univ. of Toronto, ON (Canada). Inst. for Aerospace Studies
  4. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  5. General Atomics, San Diego, CA (United States)
  6. Julich Research Centre (Germany). Inst. of Energy and Climate Research- Plasma Physics
  7. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  8. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  9. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  10. Univ. of Vienna (Austria). Fusion @OAW. Inst. of Applied Physics
Publication Date:
Report Number(s):
Journal ID: ISSN 0029-5515; 650168
Grant/Contract Number:
AC04-94AL85000; GA-DE-SC0008698; AC05-06OR23100; FG02-07ER54917; AC05-00OR22725; FC02-04ER54698; AC52-07NA27344
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 57; Journal Issue: 5; Journal ID: ISSN 0029-5515
IOP Science
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; erosion; deposition; high-Z materials; impurity
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1374606; OSTI ID: 1374610