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Title: Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D

Experiments have been conducted on DIII-D investigating high repetition rate injection of non-fuel pellets as a tool for pacing Edge Localized Modes (ELMs) and mitigating their transient divertor heat loads. Effective ELM pacing was obtained with injection of Li granules in different H-mode scenarios, at frequencies 3–5 times larger than the natural ELM frequency, with subsequent reduction of strike-point heat flux. However, in scenarios with high pedestal density (~6 × 10 19 m –3), the magnitude of granule triggered ELMs shows a broad distribution, in terms of stored energy loss and peak heat flux, challenging the effectiveness of ELM mitigation. Furthermore, transient heat-flux deposition correlated with granule injections was observed far from the strike-points. As a result, field line tracing suggest this phenomenon to be consistent with particle loss into the mid-plane far scrape-off layer, at toroidal location of the granule injection.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [3] ; ORCiD logo [1] ;  [4] ;  [4] ;  [1] ;  [3] ;  [2]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-09CH114661; AC05-00OR227252; FC02-04ER546983; FG02-06ER54867; AC52-07NA273444; FC02-04ER54698; AC02-09CH11466; AC05-00OR22725; AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Nuclear Materials and Energy
Additional Journal Information:
Journal Volume: 12; Related Information: 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.; Journal ID: ISSN 2352-1791
Publisher:
Elsevier
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); USDOE Office of Nuclear Energy (NE)
Contributing Orgs:
DIII-D team
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1349223
Alternate Identifier(s):
OSTI ID: 1374820

Bortolon, A., Maingi, R., Mansfield, D. K., Nagy, A., Roquemore, A. L., Baylor, L. R., Commaux, N., Jackson, G. L., Lunsford, R., Lasnier, C. J., Makowski, M. J., Nazikian, R., Osborne, T. H., and Shiraki, D.. Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D. United States: N. p., Web. doi:10.1016/j.nme.2017.01.003.
Bortolon, A., Maingi, R., Mansfield, D. K., Nagy, A., Roquemore, A. L., Baylor, L. R., Commaux, N., Jackson, G. L., Lunsford, R., Lasnier, C. J., Makowski, M. J., Nazikian, R., Osborne, T. H., & Shiraki, D.. Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D. United States. doi:10.1016/j.nme.2017.01.003.
Bortolon, A., Maingi, R., Mansfield, D. K., Nagy, A., Roquemore, A. L., Baylor, L. R., Commaux, N., Jackson, G. L., Lunsford, R., Lasnier, C. J., Makowski, M. J., Nazikian, R., Osborne, T. H., and Shiraki, D.. 2017. "Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D". United States. doi:10.1016/j.nme.2017.01.003. https://www.osti.gov/servlets/purl/1349223.
@article{osti_1349223,
title = {Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D},
author = {Bortolon, A. and Maingi, R. and Mansfield, D. K. and Nagy, A. and Roquemore, A. L. and Baylor, L. R. and Commaux, N. and Jackson, G. L. and Lunsford, R. and Lasnier, C. J. and Makowski, M. J. and Nazikian, R. and Osborne, T. H. and Shiraki, D.},
abstractNote = {Experiments have been conducted on DIII-D investigating high repetition rate injection of non-fuel pellets as a tool for pacing Edge Localized Modes (ELMs) and mitigating their transient divertor heat loads. Effective ELM pacing was obtained with injection of Li granules in different H-mode scenarios, at frequencies 3–5 times larger than the natural ELM frequency, with subsequent reduction of strike-point heat flux. However, in scenarios with high pedestal density (~6 × 1019 m–3), the magnitude of granule triggered ELMs shows a broad distribution, in terms of stored energy loss and peak heat flux, challenging the effectiveness of ELM mitigation. Furthermore, transient heat-flux deposition correlated with granule injections was observed far from the strike-points. As a result, field line tracing suggest this phenomenon to be consistent with particle loss into the mid-plane far scrape-off layer, at toroidal location of the granule injection.},
doi = {10.1016/j.nme.2017.01.003},
journal = {Nuclear Materials and Energy},
number = ,
volume = 12,
place = {United States},
year = {2017},
month = {3}
}