Speaker
Shaodong Song
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.1071.pdf
ECRH H-mode Experiments in the HL-2A Tokamak
S. D. Song1, J. Rao1, M. Huang1, X.L.Zou2, H. Wang1, D. H. Xia3, Z. H. Kang1, K. Feng1, M.
W. Wang1, Y. N. Bu1, B. Lu1, C. Wang1, X. Y. Bai1, X.M. Song1, B.B. Feng1, C.Y. Chen1, W.
L. Zhong1, Z.Y. Cui1, Z.B. Shi1, D.L. Yu1, M. Jiang1, Y. Zhou1, Y.G. Li1, M. Xu1, Yi Liu1, Z.
Cao1, L. Y. Yao1, W. M. Xuan1, L.W. Yan1, Q.W. Yang1, L.H. Yao1, X.T. Ding1, J.Q. Dong1,
X. R. Duan1 and Yong Liu1
1
Southwestern Institute of Physics, P.O. Box 432, Chengdu, Sichuan, 610041, China
2
CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
3
Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, China
Heating in electron and ion channel plays different role in the scope of L-H transition [1].
In HL-2A tokamak 5MW ECRH system [2, 3] and 1.5MW NBI system have been equipped.
The first H-mode on HL-2A was obtained in 2009 [4], with both NBI and ECRH. After that
H-mode was also obtained with purely NBI. Although the total ECRH power is much higher
than the NBI power, steady H-mode on HL-2A with purely ECRH has not been realised.
However, clear evidence of limit cycle oscillation (LCO) and ELMy like phenomena on D
signal in purely ECRH discharges has been observed, which indicates the plasma has entered
into the intermediate phase (I-phase) toward steady H-mode.
Shot 21886 (Bt = 1.32T, Ip = 155kA, PECRH = 1.6MW) gives an example for such ECRH
I-phase discharges. In the experiments, SMBI is employed to mitigate the density pump out
[5, 6]
effect during ECRH phase. Oscillation at frequency 2~3 kHz on D signal in t =
730~750ms and formation of edge density pedestal support the assertion of plasma
confinement mode transition. However, the I-phase does not last long since the plasma
density keep decreasing which improves the L-H transition threshold. Employing feedback
control of density using SMBI to keep density constant, quasi-continuous LCO has also been
clearly observed as in the case of shot 23065(Bt = 1.31T, Ip = 172kA, PECRH = 1.6MW, ne ~
1.7×1019/m3). However, transition to steady ELMy H-mode has not yet been realised. The
reason may be due to the enhancement of TEM instabilities and turbulence in ECRH phase.
References
[1] F. Ryter T. Pütterich, M. Reich, et al., 2009 Nucl. Fusion 49 062003
[2] M. Huang, J. Rao, B. Li, et al. 3MW ECRH system and experiments on HL-2A. 37th EPS conference,
Dublin, Ireland. 2010.
[3] M. Huang et al. Development of a 140 GHz steerable launcher for the HL-2A ECRH system. Plasma Sci.
Technol. 15 (2013) 1247-1253
[4] X.R. Duan, J.Q. Dong, L.W. Yan, et al., Nucl. Fusion 50, 095011(2010)
[5] X.L. Zou, W.W. Xiao, S.D. Song, et al. Particle Transport Investigation in HL-2A Using ECRH and SMBI,
23rd IAEA Fusion Energy Conference, Daejeon. (2012)
[6] C. Angioni, A.G. Peeters, X. Garbet, et al., Nucl. Fusion 44, 827 (2004)
