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Title: High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges

Abstract

A newly installed Lithium Granule Injector (LGI) was used to pace edge localized modes (ELM) in DIII-D. ELM pacing efficiency was studied injecting lithium granules of nominal diameter 0.3–0.9mm, speed of 50–120 m s -1 and average injection rates up to 100 Hz for 0.9mm granules and up to 700 Hz for 0.3mm granules. The efficiency of ELM triggering was found to depend strongly on size of the injected granules, with triggering efficiency close to 100% obtained with 0.9mm diameter granules, lower with smaller sizes, and weakly depending on granule velocity. Robust ELM pacing was demonstrated in ITER-like plasmas for the entire shot length, at ELM frequencies 3–5 times larger than the ‘natural’ ELM frequency observed in reference discharges. Within the range of ELM frequencies obtained, the peak ELM heat flux at the outer strike point was reduced with increasing pacing frequency. The peak heat flux reduction at the inner strike point appears to saturate at high pacing frequency. Lithium was found in the plasma core, with a concurrent reduction of metallic impurities and carbon. Altogether, high frequency ELM pacing using the lithium granule injection appears to be compatible with both H-mode energy confinement and attractive H-mode pedestal characteristics, butmore » further assessment is need« less

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [1];  [2];  [2];  [3];  [1]; ORCiD logo [1];  [3];  [4];  [1];  [3]; ORCiD logo [1];  [5];  [5];  [1];  [3];  [2] more »;  [3] « less
  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. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  5. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); U.S. Department of Energy, Washington D.C. (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
Contributing Org.:
Princeton Plasma Physics Laboratory, Princeton, NJ; Oak Ridge National Laboratory, Oak Ridge, TN; General Atomics, San Diego, CA; Oak Ridge Associated Universities, Oak Ridge, TN; Lawrence Livermore National Laboratory, CA
OSTI Identifier:
1254013
Alternate Identifier(s):
OSTI ID: 1246536; OSTI ID: 1459511; OSTI ID: 1542718
Report Number(s):
PPPL-5251; LLNL-JRNL-752101
Journal ID: ISSN 0029-5515
Grant/Contract Number:  
AC02-09CH11466; FC02-04ER54698; AC52-07NA27344; AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 56; Journal Issue: 5; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tokamak; ELM; pacing; pellet; mitigation; head load; control; Physics - Plasma physics

Citation Formats

Bortolon, A., Maingi, R., Mansfield, D. K., Nagy, A., Roquemore, A. L., Baylor, L. R., Commaux, N., Jackson, G. L., Gilson, E. P., Lunsford, R., Parks, P. B., Chrystal, C., Grierson, B. A., Groebner, R., Haskey, S. R., Makowski, M. J., Lasnier, C. J., Nazikian, R., Osborne, T., Shiraki, D., and Van Zeeland, M. A. High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges. United States: N. p., 2016. Web. doi:10.1088/0029-5515/56/5/056008.
Bortolon, A., Maingi, R., Mansfield, D. K., Nagy, A., Roquemore, A. L., Baylor, L. R., Commaux, N., Jackson, G. L., Gilson, E. P., Lunsford, R., Parks, P. B., Chrystal, C., Grierson, B. A., Groebner, R., Haskey, S. R., Makowski, M. J., Lasnier, C. J., Nazikian, R., Osborne, T., Shiraki, D., & Van Zeeland, M. A. High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges. United States. doi:10.1088/0029-5515/56/5/056008.
Bortolon, A., Maingi, R., Mansfield, D. K., Nagy, A., Roquemore, A. L., Baylor, L. R., Commaux, N., Jackson, G. L., Gilson, E. P., Lunsford, R., Parks, P. B., Chrystal, C., Grierson, B. A., Groebner, R., Haskey, S. R., Makowski, M. J., Lasnier, C. J., Nazikian, R., Osborne, T., Shiraki, D., and Van Zeeland, M. A. Fri . "High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges". United States. doi:10.1088/0029-5515/56/5/056008. https://www.osti.gov/servlets/purl/1254013.
@article{osti_1254013,
title = {High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges},
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 Gilson, E. P. and Lunsford, R. and Parks, P. B. and Chrystal, C. and Grierson, B. A. and Groebner, R. and Haskey, S. R. and Makowski, M. J. and Lasnier, C. J. and Nazikian, R. and Osborne, T. and Shiraki, D. and Van Zeeland, M. A.},
abstractNote = {A newly installed Lithium Granule Injector (LGI) was used to pace edge localized modes (ELM) in DIII-D. ELM pacing efficiency was studied injecting lithium granules of nominal diameter 0.3–0.9mm, speed of 50–120 m s-1 and average injection rates up to 100 Hz for 0.9mm granules and up to 700 Hz for 0.3mm granules. The efficiency of ELM triggering was found to depend strongly on size of the injected granules, with triggering efficiency close to 100% obtained with 0.9mm diameter granules, lower with smaller sizes, and weakly depending on granule velocity. Robust ELM pacing was demonstrated in ITER-like plasmas for the entire shot length, at ELM frequencies 3–5 times larger than the ‘natural’ ELM frequency observed in reference discharges. Within the range of ELM frequencies obtained, the peak ELM heat flux at the outer strike point was reduced with increasing pacing frequency. The peak heat flux reduction at the inner strike point appears to saturate at high pacing frequency. Lithium was found in the plasma core, with a concurrent reduction of metallic impurities and carbon. Altogether, high frequency ELM pacing using the lithium granule injection appears to be compatible with both H-mode energy confinement and attractive H-mode pedestal characteristics, but further assessment is need},
doi = {10.1088/0029-5515/56/5/056008},
journal = {Nuclear Fusion},
issn = {0029-5515},
number = 5,
volume = 56,
place = {United States},
year = {2016},
month = {4}
}

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