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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 (PFCs). 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:
ORCiD logo [1];  [2];  [3];  [3]; ORCiD logo [1]; ORCiD logo [1];  [1];  [4];  [1]
  1. ORNL
  2. EURATOM / UKAEA, Abingdon, UK
  3. Lawrence Livermore National Laboratory (LLNL)
  4. ITER Organization, Cadarache, France
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1424505
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Journal Volume: 463; Conference: 21st International Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI 2014) - Kanazawa, , Japan - 5/26/2014 12:00:00 PM-5/30/2014 12:00:00 PM
Country of Publication:
United States
Language:
English

Citation Formats

Baylor, Larry R., Lang, P., Allen, S. L., Lasnier, C. J., Meitner, Steven J., Combs, Stephen Kirk, Commaux, Nicolas JC, Loarte, A., and Jernigan, Thomas C. ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER. United States: N. p., 2015. Web. doi:10.1016/j.jnucmat.2014.09.070.
Baylor, Larry R., Lang, P., Allen, S. L., Lasnier, C. J., Meitner, Steven J., Combs, Stephen Kirk, Commaux, Nicolas JC, Loarte, A., & Jernigan, Thomas C. ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER. United States. doi:10.1016/j.jnucmat.2014.09.070.
Baylor, Larry R., Lang, P., Allen, S. L., Lasnier, C. J., Meitner, Steven J., Combs, Stephen Kirk, Commaux, Nicolas JC, Loarte, A., and Jernigan, Thomas C. Sat . "ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER". United States. doi:10.1016/j.jnucmat.2014.09.070. https://www.osti.gov/servlets/purl/1424505.
@article{osti_1424505,
title = {ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER},
author = {Baylor, Larry R. and Lang, P. and Allen, S. L. and Lasnier, C. J. and Meitner, Steven J. and Combs, Stephen Kirk and Commaux, Nicolas JC and Loarte, A. and Jernigan, Thomas C.},
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 (PFCs). 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},
journal = {},
issn = {0022-3115},
number = ,
volume = 463,
place = {United States},
year = {2015},
month = {8}
}

Conference:
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