Speaker
Ze Bao Song
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.1018.pdf
Preliminary investigation of the helical current induced by electrode biasing
in the SOL on the J-TEXT tokamak
Zebao Song1,*, Nengchao Wang1,*, Y. Liang1, 2, 3, Jie Yang1, Tong Wang1, Huaxiang Zhang3,
Yunong Wei1, Da Li1, Y. H. Ding1 and the J-TEXT team
1
International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma
Physics, Huazhong University of Science and Technology, Wuhan, China
2
Forschungszentrum Jülich, Jülich, Germany
3
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
*E-mail: zb_song@hust.edu.cn, wangnc@hust.edu.cn
An essential problem for future burning plasma is that the Edge-Localized Modes (ELMs)
could erode and melt the plasma-facing components. Therefore, the effective control of ELMs
is of great importance. Extensive experiments have demonstrated that the resonant magnetic
perturbations (RMPs) generated by in-vessel or ex-vessel saddle coils can change the edge
magnetic topology and hence mitigate or even suppress the ELMs. Similar as the RMPs, the
helical current filaments (HCFs) induced by lower hybrid waves has been observed to change
the magnetic topology and strongly mitigate ELMs in EAST [1]. The HCFs could be a new
attractive method to apply RMPs. According to analytical calculation, the sufficient SOL helical
current could be produced by biasing the divertor plates asymmetrically in order to control
ELMs in ITER [2].
In this paper, we will present the recent results on the HCFs actively driven by a moveable
biased electrode in the SOL of J-TEXT. Once the biasing voltage (e.g. +200V) was applied to
the electrode, significant current (~150 A) was induced through the electrode. The perturbed
magnetic fields produced by the biasing current were measured at two poloidal cross-sections.
The total magnetic fields, generated by the helical currents flowing both along and against the
magnetic field lines at the location of the electrode, were calculated at the same cross-sections.
The measured and calculated magnetic fields are highly consistent, which confirmed that the
current induced by the electrode flowed helically along and against the local magnetic field
lines. In addition, the radiation of the HCFs were observed from the images captured by a fast
frame visible camera with the CIII filter. The spectrum of the magnetic field generated by the
HCFs were calculated, which resonate with the edge rational surfaces and hence modify the
edge magnetic topology significantly.
References:
[1] Y. Liang, et al. Physical Review Letters 110 (2013) 235002.
[2] Joseph I, et al. Physics of Plasmas 16 (2009) 052511.
