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

Journal Article · · Nuclear Fusion
ORCiD logo [1];  [2]; ORCiD logo [1];  [1];  [1];  [2];  [2];  [2];  [1];  [3];  [4];  [5];  [6];  [2];  [2];  [2];  [2]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Chinese Academy of Sciences, Anhui (People's Republic of China)
  3. General Atomics, San Diego, CA (United States)
  4. Johns Hopkins Univ., Baltimore, MD (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. Hunan Univ., Changsha (People's Republic of China)
+ Show Author Affiliations

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.

Research Organization:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Organization:
USDOE
Contributing Organization:
The EAST team
Grant/Contract Number:
AC02-09CH11466; FC02-04ER54698; FG02-09ER55012; 11321092; 11405210; 11605246; 11625524; 2013GB114004; 2017YFA0402500; 2017YFE0301100
OSTI ID:
1480326
Journal Information:
Nuclear Fusion, Vol. 58, Issue 12; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 10 works
Citation information provided by
Web of Science

References (31)

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Figures / Tables (14)

Table 1(p. 8)table Table 1
Figure 1(p. 25)figure Figure 1
Figure 2(p. 26)figure Figure 2
Figure 3(p. 27)figure Figure 3
Figure 4(p. 28)figure Figure 4
Figure 5(p. 29)figure Figure 5
Figure 6(p. 30)figure Figure 6
Figure 7(p. 31)figure Figure 7
Figure 8(p. 32)figure Figure 8
Figure 9(p. 33)figure Figure 9
Figure 10(p. 34)figure Figure 10
Figure 11(p. 35)figure Figure 11
Figure 12(p. 36)figure Figure 12
Figure 13(p. 37)figure Figure 13

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