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

Lunsford, R.; Hu, 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.; Zang, Q.; Gong, X. Z.; Wan, B. N.; Li, J. G.

doi:10.1088/1741-4326/aae2c1

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

Journal Article · Wed Oct 10 00:00:00 EDT 2018 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/aae2c1· OSTI ID:1480326

^[1]; Hu, J. S. ^[2]; ^[1]; Maingi, R. ^[1]; Mansfield, D. K. ^[1]; Xu, W. ^[2]; Zuo, G. Z. ^[2]; Huang, M. ^[2]; Diallo, A. ^[1]; Osborne, T. ^[3]; Tritz, K. ^[4]; Canik, J. ^[5]; Meng, X. C. ^[6]; Zang, Q. ^[2]; Gong, X. Z. ^[2]; Wan, B. N. ^[2]; Li, J. G. ^[2]

Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Chinese Academy of Sciences, Anhui (People's Republic of China)
General Atomics, San Diego, CA (United States)
Johns Hopkins Univ., Baltimore, MD (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Hunan Univ., Changsha (People's Republic of China)

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. Furthermore, 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 ~2.4 × multiplication of the natural ELM frequency and a 50% decrease of the ELM size.

View Accepted Manuscript (DOE)

Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: USDOE

Contributing Organization:: The EAST team

Grant/Contract Number:: AC02-09CH11466; FC02-04ER54698

OSTI ID:: 1480326

Alternate ID(s):: OSTI ID: 22929588

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 12 Vol. 58; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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