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

Abstract

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 [Bortolon et al, Nucl. Fus., 56, 056008, 2016]. 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. 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:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE Office of Nuclear Energy (NE); USDOE National Nuclear Security Administration (NNSA)
Contributing Org.:
DIII-D team
OSTI Identifier:
1349223
Alternate Identifier(s):
OSTI ID: 1374820; OSTI ID: 1542749
Report Number(s):
LLNL-JRNL-779846
Journal ID: ISSN 2352-1791; PII: S2352179116302411
Grant/Contract Number:  
AC02-09CH114661; AC05-00OR227252; FC02-04ER546983; FG02-06ER54867; AC52-07NA273444; FC02-04ER54698; AC02-09CH11466; AC05-00OR22725; AC52-07NA27344
Resource 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
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

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., 2017. Web. https://doi.org/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. https://doi.org/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. Thu . "Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D". United States. https://doi.org/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 [Bortolon et al, Nucl. Fus., 56, 056008, 2016]. 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. 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}
}

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Works referenced in this record:

Progress on the application of ELM control schemes to ITER scenarios from the non-active phase to DT operation
journal, February 2014


ELM pace making and mitigation by pellet injection in ASDEX Upgrade
journal, April 2004


First observations of ELM triggering by injected lithium granules in EAST
journal, September 2013


High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges
journal, April 2016


Lithium granule ablation and penetration during ELM pacing experiments at DIII-D
journal, November 2016


Effect of n=3 perturbation field amplitudes below the ELM triggering threshold on edge and SOL transport in NSTX
journal, July 2013


Reduction of edge localized mode intensity on DIII-D by on-demand triggering with high frequency pellet injection and implications for ITER
journal, August 2013

  • Baylor, L. R.; Commaux, N.; Jernigan, T. C.
  • Physics of Plasmas, Vol. 20, Issue 8
  • DOI: 10.1063/1.4818772

Infrared thermography of the DIII‐D divertor targets
journal, August 1988

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  • DOI: 10.1063/1.1140040

Broadening of divertor heat flux profile with increasing number of ELM filaments in NSTX
journal, November 2014


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journal, November 2014

  • Lasnier, C. J.; Allen, S. L.; Ellis, R. E.
  • Review of Scientific Instruments, Vol. 85, Issue 11
  • DOI: 10.1063/1.4892897

Scrape-off layer heat transport and divertor power deposition of pellet-induced edge localized modes
journal, August 2011


Advances in understanding and utilising ELM control in JET
journal, January 2016


ELM pacing using modulated non-axisymmetric magnetic fields on DIII-D
journal, March 2012


ELM pacing and trigger investigations at JET with the new ITER-like wall
journal, May 2013


Calculations of two-fluid magnetohydrodynamic axisymmetric steady-states
journal, November 2009


    Works referencing / citing this record:

    Ablation of solid pellets induced by supra-thermal ions in the far scrape-off layer of DIII-D plasmas
    journal, June 2019


    ELM frequency enhancement and discharge modification through lithium granule injection into EAST H-modes
    journal, October 2018


    Erosion dynamics of tungsten fuzz during ELM-like heat loading
    journal, April 2018

    • Sinclair, G.; Tripathi, J. K.; Hassanein, A.
    • Journal of Applied Physics, Vol. 123, Issue 13
    • DOI: 10.1063/1.5023665