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

Abstract

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. Different methods such as electrical biasing and local gas injection have been investigated 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 13CH4 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. In H-mode plasmas, the measured inter-ELM W erosion rates at different radial locations are well reproduced by ERO modelingmore » taking into account charge-state-resolved carbon ion flux in the background plasma calculated using the OEDGE code.« less

Authors:
 [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:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); General Atomics, San Diego, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1491638
Alternate Identifier(s):
OSTI ID: 1357016; OSTI ID: 1374606; OSTI ID: 1374610; OSTI ID: 1503985
Report Number(s):
LLNL-JRNL-736452; SAND-2017-0016J
Journal ID: ISSN 0029-5515; 836266
Grant/Contract Number:  
AC52-07NA27344; AC04-94AL85000; GA-DE-SC0008698; AC05-06OR23100; FG02-07ER54917; AC05-00OR22725; FC02-04ER54698
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 57; Journal Issue: 5; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; erosion; deposition; high-Z materials; impurity

Citation Formats

Ding, R., Rudakov, D. L., Stangeby, P. C., Wampler, W. R., Abrams, T., Brezinsek, S., Briesemeister, A., Bykov, I., Chan, V. S., Chrobak, C. P., Elder, J. D., Guo, H. Y., Guterl, J., Kirschner, A., Lasnier, C. J., Leonard, A. W., Makowski, M. A., McLean, A. G., Snyder, P. B., Thomas, D. M., Tskhakaya, D., Unterberg, E. A., Wang, H. Q., and Watkins, J. G. Advances in understanding of high- Z material erosion and re-deposition in low-Z wall environment in DIII-D. United States: N. p., 2017. Web. doi:10.1088/1741-4326/aa6451.
Ding, R., Rudakov, D. L., Stangeby, P. C., Wampler, W. R., Abrams, T., Brezinsek, S., Briesemeister, A., Bykov, I., Chan, V. S., Chrobak, C. P., Elder, J. D., Guo, H. Y., Guterl, J., Kirschner, A., Lasnier, C. J., Leonard, A. W., Makowski, M. A., McLean, A. G., Snyder, P. B., Thomas, D. M., Tskhakaya, D., Unterberg, E. A., Wang, H. Q., & Watkins, J. G. Advances in understanding of high- Z material erosion and re-deposition in low-Z wall environment in DIII-D. United States. doi:https://doi.org/10.1088/1741-4326/aa6451
Ding, R., Rudakov, D. L., Stangeby, P. C., Wampler, W. R., Abrams, T., Brezinsek, S., Briesemeister, A., Bykov, I., Chan, V. S., Chrobak, C. P., Elder, J. D., Guo, H. Y., Guterl, J., Kirschner, A., Lasnier, C. J., Leonard, A. W., Makowski, M. A., McLean, A. G., Snyder, P. B., Thomas, D. M., Tskhakaya, D., Unterberg, E. A., Wang, H. Q., and Watkins, J. G. Fri . "Advances in understanding of high- Z material erosion and re-deposition in low-Z wall environment in DIII-D". United States. doi:https://doi.org/10.1088/1741-4326/aa6451. https://www.osti.gov/servlets/purl/1491638.
@article{osti_1491638,
title = {Advances in understanding of high- Z material erosion and re-deposition in low-Z wall environment in DIII-D},
author = {Ding, R. and Rudakov, D. L. and Stangeby, P. C. and Wampler, W. R. and Abrams, T. and Brezinsek, S. and Briesemeister, A. and Bykov, I. and Chan, V. S. and Chrobak, C. P. and Elder, J. D. and Guo, H. Y. and Guterl, J. and Kirschner, A. and Lasnier, C. J. and Leonard, A. W. and Makowski, M. A. and McLean, A. G. and Snyder, P. B. and Thomas, D. M. and Tskhakaya, D. and Unterberg, E. A. and Wang, H. Q. and Watkins, J. G.},
abstractNote = {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. Different methods such as electrical biasing and local gas injection have been investigated 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 13CH4 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. In H-mode plasmas, the measured inter-ELM W erosion rates at different radial locations are well reproduced by ERO modeling taking into account charge-state-resolved carbon ion flux in the background plasma calculated using the OEDGE code.},
doi = {10.1088/1741-4326/aa6451},
journal = {Nuclear Fusion},
number = 5,
volume = 57,
place = {United States},
year = {2017},
month = {3}
}

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Figures / Tables:

Figure 1 Figure 1: Photographs of various samples for different experiments: (a) Mo sample for gross and net erosion measurements, (b) Mo sample after exposure with methane injection, (c) Mo sample for electrical biasing and (d) W sample after exposure with deuterium injection.

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journal, August 2015


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    Works referencing / citing this record:

    Plasma cleaning of ITER edge Thomson scattering mock-up mirror in the EAST tokamak
    journal, December 2017


      Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.