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Title: ELM frequency enhancement and discharge modification through lithium granule injection into EAST H-modes

Abstract

The injection of impurity granules into fusion research discharges can serve as a catalyst for ELM events. For sufficiently low ELM frequencies, and granule sizes above a threshold, this can result in full control of the ELM cycle, referred to as ELM pacing. For this research, we extend the investigation to conditions where the natural ELM frequency is too high for ELM pacing to be realized. Utilizing multiple sizes of lithium granules and classifying their effects by granule size, we demonstrate that ELM mitigation through frequency multiplication can be used at ELM triggering rates that nominally make ELM pacing unrealizable. We find that above a size threshold, injected granules promptly trigger ELMs and commensurately enhance the ELM frequency . Below this threshold size, injection of an individual granule does not always lead to the prompt triggering of an ELM; however, collective ablation in the edge pedestal region does enhance the ELM frequency. Specifically, Li granules too small to individually trigger ELMs were injected into EAST H-mode discharges at frequencies up to 2.3 kHz; collectively the granules were observed to enhance the natural ELM frequency up to 620 Hz, resulting in a ~2.4x multiplication of the natural ELM frequency and amore » 50% decrease of the ELM size.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
U. S. Department of Energy
OSTI Identifier:
1562100
DOE Contract Number:  
AC02-09CH11466
Resource Type:
Data
Country of Publication:
United States
Language:
English
Subject:
Granules

Citation Formats

Lunsford,, Hsu, J S, Sun, Z, Maingi, R, Mansfield, D K, Xu, W, Zuo, G Z, Huang, M, Diallo, A, Osborne, T, Tritz, K, Canik, J, Meng, X C, Gong, X Z, Wan, B N, Li, J G, and Team, EAST. ELM frequency enhancement and discharge modification through lithium granule injection into EAST H-modes. United States: N. p., 2018. Web. doi:10.11578/1562100.
Lunsford,, Hsu, J S, Sun, Z, Maingi, R, Mansfield, D K, Xu, W, Zuo, G Z, Huang, M, Diallo, A, Osborne, T, Tritz, K, Canik, J, Meng, X C, Gong, X Z, Wan, B N, Li, J G, & Team, EAST. ELM frequency enhancement and discharge modification through lithium granule injection into EAST H-modes. United States. doi:10.11578/1562100.
Lunsford,, Hsu, J S, Sun, Z, Maingi, R, Mansfield, D K, Xu, W, Zuo, G Z, Huang, M, Diallo, A, Osborne, T, Tritz, K, Canik, J, Meng, X C, Gong, X Z, Wan, B N, Li, J G, and Team, EAST. Mon . "ELM frequency enhancement and discharge modification through lithium granule injection into EAST H-modes". United States. doi:10.11578/1562100. https://www.osti.gov/servlets/purl/1562100.
@article{osti_1562100,
title = {ELM frequency enhancement and discharge modification through lithium granule injection into EAST H-modes},
author = {Lunsford, and Hsu, J S and Sun, Z and Maingi, R and Mansfield, D K and Xu, W and Zuo, G Z and Huang, M and Diallo, A and Osborne, T and Tritz, K and Canik, J and Meng, X C and Gong, X Z and Wan, B N and Li, J G and Team, EAST},
abstractNote = {The injection of impurity granules into fusion research discharges can serve as a catalyst for ELM events. For sufficiently low ELM frequencies, and granule sizes above a threshold, this can result in full control of the ELM cycle, referred to as ELM pacing. For this research, we extend the investigation to conditions where the natural ELM frequency is too high for ELM pacing to be realized. Utilizing multiple sizes of lithium granules and classifying their effects by granule size, we demonstrate that ELM mitigation through frequency multiplication can be used at ELM triggering rates that nominally make ELM pacing unrealizable. We find that above a size threshold, injected granules promptly trigger ELMs and commensurately enhance the ELM frequency . Below this threshold size, injection of an individual granule does not always lead to the prompt triggering of an ELM; however, collective ablation in the edge pedestal region does enhance the ELM frequency. Specifically, Li granules too small to individually trigger ELMs were injected into EAST H-mode discharges at frequencies up to 2.3 kHz; collectively the granules were observed to enhance the natural ELM frequency up to 620 Hz, resulting in a ~2.4x multiplication of the natural ELM frequency and a 50% decrease of the ELM size.},
doi = {10.11578/1562100},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {10}
}

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