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

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:
Grant/Contract Number:
FC02-04ER54698; AC05-00OR22725; FG02-07ER54917; AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 463; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Research Org:
General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY Plasma properties; Gases; Gas injection & Fueling; Pellet; DIII-D; ELM
OSTI Identifier:
1375959
Alternate Identifier(s):
OSTI ID: 1375959