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Title: ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER

Abstract

The triggering of rapid small edge localized modes (ELMs) by high frequency pellet injection has been proposed as a method to prevent large naturally occurring ELMs that can erode the ITER plasma facing components. Deuterium pellet injection has been used to successfully demonstrate the on-demand triggering of edge localized modes (ELMs) at much higher rates and with much smaller intensity than natural ELMs. The proposed hypothesis for the triggering mechanism of ELMs by pellets is the local pressure perturbation resulting from reheating of the pellet cloud that can exceed the local high-n ballooning mode threshold where the pellet is injected. Nonlinear MHD simulations of the pellet ELM triggering show destabilization of high-n ballooning modes by such a local pressure perturbation. A review of the recent pellet ELM triggering results from ASDEX Upgrade (AUG), DIII-D, and JET reveals that a number of uncertainties about this ELM mitigation technique still remain. These include the heat flux impact pattern on the divertor and wall from pellet triggered and natural ELMs, the necessary pellet size and injection location to reliably trigger ELMs, and the level of fueling to be expected from ELM triggering pellets and synergy with larger fueling pellets. The implications of thesemore » issues for pellet ELM mitigation in ITER and its impact on the PFCs are presented along with the design features of the pellet injection system for ITER.« less

Authors:
 [1];  [2];  [3];  [1];  [1];  [4];  [3];  [5];  [1];  [3];  [4];  [5];  [6];  [5];  [1];  [7];  [4]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Max Planck Inst. fur Plasmaphysik, Garching (Germany)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. General Atomics, San Diego, CA (United States)
  5. ITER Organization, St. Paul Lez Durance (France)
  6. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  7. Univ. of California, San Diego, CA (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1375959
Alternate Identifier(s):
OSTI ID: 1252293
Grant/Contract Number:  
FC02-04ER54698; AC05-00OR22725; FG02-07ER54917; AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 463; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Plasma properties; Gases; Gas injection & Fueling; Pellet; DIII-D; ELM

Citation Formats

Baylor, Larry R., Lang, P. T., Allen, Steve L., Combs, S. K., Commaux, N., Evans, Todd E., Fenstermacher, Max E., Huijsmans, G., Jernigan, T. C., Lasnier, Charles J., Leonard, Anthony W., Loarte, Alberto, Maingi, Rajesh, Maruyama, S., Meitner, S. J., Moyer, Richard A., and Osborne, Thomas H. ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER. United States: N. p., 2014. Web. doi:10.1016/j.jnucmat.2014.09.070.
Baylor, Larry R., Lang, P. T., Allen, Steve L., Combs, S. K., Commaux, N., Evans, Todd E., Fenstermacher, Max E., Huijsmans, G., Jernigan, T. C., Lasnier, Charles J., Leonard, Anthony W., Loarte, Alberto, Maingi, Rajesh, Maruyama, S., Meitner, S. J., Moyer, Richard A., & Osborne, Thomas H. ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER. United States. https://doi.org/10.1016/j.jnucmat.2014.09.070
Baylor, Larry R., Lang, P. T., Allen, Steve L., Combs, S. K., Commaux, N., Evans, Todd E., Fenstermacher, Max E., Huijsmans, G., Jernigan, T. C., Lasnier, Charles J., Leonard, Anthony W., Loarte, Alberto, Maingi, Rajesh, Maruyama, S., Meitner, S. J., Moyer, Richard A., and Osborne, Thomas H. 2014. "ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER". United States. https://doi.org/10.1016/j.jnucmat.2014.09.070. https://www.osti.gov/servlets/purl/1375959.
@article{osti_1375959,
title = {ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER},
author = {Baylor, Larry R. and Lang, P. T. and Allen, Steve L. and Combs, S. K. and Commaux, N. and Evans, Todd E. and Fenstermacher, Max E. and Huijsmans, G. and Jernigan, T. C. and Lasnier, Charles J. and Leonard, Anthony W. and Loarte, Alberto and Maingi, Rajesh and Maruyama, S. and Meitner, S. J. and Moyer, Richard A. and Osborne, Thomas H.},
abstractNote = {The triggering of rapid small edge localized modes (ELMs) by high frequency pellet injection has been proposed as a method to prevent large naturally occurring ELMs that can erode the ITER plasma facing components. Deuterium pellet injection has been used to successfully demonstrate the on-demand triggering of edge localized modes (ELMs) at much higher rates and with much smaller intensity than natural ELMs. The proposed hypothesis for the triggering mechanism of ELMs by pellets is the local pressure perturbation resulting from reheating of the pellet cloud that can exceed the local high-n ballooning mode threshold where the pellet is injected. Nonlinear MHD simulations of the pellet ELM triggering show destabilization of high-n ballooning modes by such a local pressure perturbation. A review of the recent pellet ELM triggering results from ASDEX Upgrade (AUG), DIII-D, and JET reveals that a number of uncertainties about this ELM mitigation technique still remain. These include the heat flux impact pattern on the divertor and wall from pellet triggered and natural ELMs, the necessary pellet size and injection location to reliably trigger ELMs, and the level of fueling to be expected from ELM triggering pellets and synergy with larger fueling pellets. The implications of these issues for pellet ELM mitigation in ITER and its impact on the PFCs are presented along with the design features of the pellet injection system for ITER.},
doi = {10.1016/j.jnucmat.2014.09.070},
url = {https://www.osti.gov/biblio/1375959}, journal = {Journal of Nuclear Materials},
issn = {0022-3115},
number = C,
volume = 463,
place = {United States},
year = {Sun Oct 05 00:00:00 EDT 2014},
month = {Sun Oct 05 00:00:00 EDT 2014}
}

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Cited by: 12 works
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Works referenced in this record:

Edge localized modes (ELMs)
journal, February 1996


Reduction of Edge-Localized Mode Intensity Using High-Repetition-Rate Pellet Injection in Tokamak H -Mode Plasmas
journal, June 2013


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


ELM pacing investigations at JET with the new pellet launcher
journal, March 2011


Modeling of stochastic magnetic flux loss from the edge of a poloidally diverted tokamak
journal, December 2002


Blob Transport in the Plasma Edge: a Review
journal, January 2009


Evolution and stratification of a plasma cloud surrounding a pellet
journal, April 1995


Edge-localized mode dynamics and transport in the scrape-off layer of the DIII-D tokamak
journal, July 2005


Investigation of pellet-triggered MHD events in ASDEX Upgrade and JET
journal, August 2008


ELM control strategies and tools: status and potential for ITER
journal, March 2013


Type-I ELM power deposition profile width and temporal shape in JET
journal, August 2011


Non-linear MHD modelling of ELM triggering by pellet injection in DIII-D and implications for ITER
journal, April 2014


Overview of recent developments in pellet injection for ITER
journal, August 2012


Comparison of deuterium pellet injection from different locations on the DIII-D tokamak
journal, October 2007


Works referencing / citing this record:

Numerical simulation of the effect of pellet injection on ELMs
journal, June 2019


Non-linear magnetohydrodynamic simulations of plasma instabilities from pellet injection in Large Helical Device plasma
journal, August 2019


Pellet-Injector Technology—Brief History and Key Developments in the Last 25 Years
journal, December 2017