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Oct 13 – 18, 2014
Hotel Park Inn Pribaltiyskaya
Europe/Moscow timezone

Comparison of ELM-Filament Mitigation between Supersonic Molecular Beam Injection and Pellet Injection in the HL-2A Tokamak

Oct 17, 2014, 8:30 AM
4h
Green 8-9 (Hotel Park Inn Pribaltiyskaya)

Green 8-9

Hotel Park Inn Pribaltiyskaya

Saint Petersburg, Russian Federation
Poster Poster 7

Speaker

Mr Lin Nie (Southwestern Institute of Physics)

Description

It is widely accepted that the transient heat flux carried by edge localized mode-filaments (ELM-filaments) can dramatically erode divertor materials, increase impurities and recycling. Thus, it is an extremely challenge to decompose heat flux originating from core plasma. In this paper, the statistical characteristics of ELM-filament within mitigation by the Supersonic Molecular Beam Injection (SMBI) and Pellet Injection (PI) have been studied. In these experiments, we use four-tip probe to measure the temporal evolution of floating potential, electron temperature and density. The injection depths are about 1~2 cm and 15~18cm inside LCFS by the SMBI and the PI, respectively. It is found that ELM amplitude reduces and its frequency increases after SMBI/PI. We extract ELM filament structure on the basis of threshold δne/σ, where σ is the standard deviation of δne. In both mitigations, larger amplitude filament burst rate decrease significantly, implies that the larger amplitude filaments are suppressed. The divertor ion-electron collisionality, and the long-range correlation are also calculated, respectively. In both ELM-mitigations, we observe that the ion-electron collisionality increases after SMBI/PI, while the long-range correlation decreases significantly. This phenomenon is in good agreement with the theory prediction that collisionality affects the parallel correlation. The particle and heat fluxes are estimated, respectively. Taking the heat fluxes for example, it is found that the transient heat fluxes decrease 50%-60% after SMBI and 40%-50% after PI. This is a direct evidence for the transient heat flux suppression. The average heat flux decreases from 1.2kW/m2 to 0.4kW/m2 after SMBI, meanwhile the thermal radiation increase, implies that there is another energy loss channel by thermal radiation, in addition to the energy loss carried by filaments. But after PI, the thermal radiation does not increase, the average heat flux only change from 1.2kW/m2 to 1.1kW/m2, almost retaining.
Paper Number EX/P7-22
Country or International Organisation China

Primary author

Mr Lin Nie (Southwestern Institute of Physics)

Co-authors

Mr Chengyuan Chen (Southwestern institute of physics) Ms Chunhua Liu (Southwestern Institute of Physics) Dr Defeng Kong (Institute of Plasma Physics Chinese Academy of Sciences) Dr Deliang Yu (Southwestern Institute of Physics) Prof. Jiaqi Dong (Southwestern Institute of Physics) Mr Jun Cheng (Southwestern Institute of Physics) Dr Kaijun Zhao (Sothwestern Institute of Physics) Prof. Lianghua Yao (southwestern institute of physics) Mr Min Xu (Southwestern Institute of Physics) Mr Wulu Zhong (Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People’s Republic of China) Dr Xiaoquan JI (Southwestern Institute of Physics, Chengdu 610041 China) Prof. Xuantong Ding (Southwestern Institute of Physics) Prof. Xuru Duan (Southwestern Institute of Physics) Dr Yuan Huang (Southwestern Institute of Physics) Prof. Yuhong Xu (Southwestern Institute of Physics) Prof. beibing Feng (Southwestern Institute of Physics) dequan liu (Southwestern Institute of Physics) genliang zhu (Southwestern Institute of Physics) Dr hongbing xu (Southwestern Institute of Physics) jie shang (Southwestern Institute of Physics) Dr jinming gao (Southwestern Institute of Physics) ke yao (Southwestern Institute of Physics) Prof. longwen Yan (southwestern institute of physics) qingwei yang (Southwestern Institute of Physics) zhen feng (Southwestern Institute of Physics) Dr zhihui huang (Southwestern Institute of Physics)

Presentation materials