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Title: Active Recycling Control Through Lithium Injection in EAST

Journal Article · · IEEE Transactions on Plasma Science
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2];  [2];  [2];  [2];  [2]; ORCiD logo [2];  [2];  [3];  [3];  [3];  [3];  [4];  [5]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Chinese Academy of Sciences, Hefei (China)
  3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  4. General Atomics, San Diego, CA (United States)
  5. Johns Hopkins Univ., Baltimore, MD (United States)
+ Show Author Affiliations

The coating of tokamak walls with thin layers of lithium has been demonstrated to reduce plasma recycling from the plasma-facing surfaces and to improve overall plasma performance. These effects, including reduced divertor D α emission, the elimination of edge-localized modes, and increased energy confinement have been observed in multiple experiments when lithium coatings are applied before plasma discharges. However, this coating technology does not extrapolate to future long-pulse devices, since the lithium coatings will be passivated by the continual plasma flux onto the surface. In order to provide active conditioning capability, a new technology has been developed that is capable of injecting lithium powder into the scrape-off layer plasma during plasma discharges, where it quickly liquefies and turns into an aerosol. The use of this “lithium dropper” is under study at the Experimental Advanced Superconducting Tokamak (EAST), where the potential benefits of real-time wall conditioning via lithium injection are being tested. Here, we present an analysis of the recycling characteristics during EAST experiments testing active lithium injection in order to assess recycling reduction and control. Lithium aerosol was injected from the top of the machine, with one system dropping lithium near the X-point and another into the low-field side divertor leg. The injection of lithium into the SOL reduced divertor recycling, as evidenced by reduced Dα emission with ion flux measured by probes relatively unchanged. This effect is strongest in the active divertor, confirming the lithium is transported to strongly plasma-wetted areas. Furthermore, quantitative analysis of the recycling changes using the SOLPS edge plasma and neutral transport code indicated a ~20% reduction in recycling coefficient with lithium injection.

Research Organization:
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
2017YFA0402500; 11625524; 11605246; 11775261; AC05-00OR22725; AC02-09CH11466; FC02- 04ER54698; SC0016553
OSTI ID:
1465373
Journal Information:
IEEE Transactions on Plasma Science, Vol. 46, Issue 5; ISSN 0093-3813
Publisher:
IEEECopyright Statement
Country of Publication:
United States
Language:
English

Cited By (2)

ELM frequency enhancement and discharge modification through lithium granule injection into EAST H-modes journal October 2018
Control of hydrogen content and fuel recycling for long pulse high performance plasma operation in EAST journal October 2019

Figures / Tables (8)

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Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
divertor
Experimental Advanced Superconducting Tokamak (EAST)
lithium wall coatings