Speaker
Rajesh Maingi
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.1021.pdf
Amelioration of Plasma-Material Interactions and ELMs, and
Improvement to Plasma Performance with Lithium Injection and
Conditioning in EAST
R. Maingi1, J.S. Hu2, D. Andruczyk3, J.M. Canik4, A. Diallo1, K.F. Gan5, E. Gilson1, X.Z
Gong2, T.K. Gray4, M. Huang2, R. Lunsford1, D.K. Mansfield1, X. C. Meng6, T.H.
Osborne7, D.N. Ruzic3, Z. Sun2, K. Tritz8, W. Xu2, G.Z. Zuo2, Z. Wang9, B.D. Wirth9, K.
Woller10, S.J. Zinkle9, and the EAST Team
1
Princeton Plasma Physics Laboratory, 100 Stellarator Road, Princeton, NJ 08540, USA
2
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
3
University of Illinois, Urbana-Champaign, Champaign IL 61820, USA
4
Oak Ridge National Laboratory Oak Ridge, TN 37830 USA
5
University of Tennessee, Knoxville TN 37996, USA
6
Department of Applied Physics, Hunan University, Changsha 410082, China
7
General Atomics, San Diego, CA 92121, USA
8
Johns Hopkins University, Baltimore MD 21211, USA
9
Los Alamos National Laboratory, Los Alamos NM 87545, USA
10
Massachusetts Institute of Technology, Cambridge MA 02139, USA
We present new results from a US-PRC boundary physics collaboration where 1) lithium
(Li) powder was injected to eliminate ELMs in upper-single null (USN) shape that used the
ITER-like tungsten monoblock divertor; 2) a 2nd generation flowing liquid lithium limiter
was inserted into the EAST midplane and used to mitigate plasma-materials interactions
(PMI); and 3) Li granule injection was used for ELM triggering studies. Li powder was
injected into upper-single null H-modes using the ITER-like tungsten monoblock divertor.
At constant injection rates, the ELM elimination became progressively easier, suggesting a
cumulative wall conditioning effect. An edge coherent mode was evident, as typical with Li
conditioning. Normalized energy confinement HH98y2 was maintained ~ 1.2, above the
previous ELM elimination with Li injection on the lower C divertor with HH98y2 ~ 0.75. A
2nd generation flowing liquid Li limiter inserted into EAST was found to be compatible
with H-modes, even when placed within 1cm of the separatrix in RF heated discharges. A
Cu plate is used for the heat sink, with a thin stainless steel coating for Li compatibility.
This limiter had several design improvements over the 1st generation limiter. The heat flux
exhausted by the 2nd generation limiter was up to 4 MW/m2. Also, short-lived ELM-free
phases were observed for the first time in EAST with increasing τE and transient HH98y2 < 2
when the 2nd generation limiter was inserted. Finally ELM triggering studies with a
four-chamber Li granule injector showed a size threshold for ELM triggering probability,
as qualitatively predicted by theory. *Research sponsored by the U.S. DoE under a
US-PRC PMI collaboration, and by a few agencies in the People’s Republic of China.
