Speaker
Shoichi Okamura
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.1034.pdf
Island bundle diverter configuration for quasi-axisymmetric stellarator
S. Okamura1, H. Liu2, A. Shimizu1, M. Isobe1, Y. Xu2
1 National Institute for Fusion Science, Toki, Japan
2 Institute of Fusion Science, Southwest Jiaotong University, Chengdu,
People’s Republic of China
National Institute for Fusion Science, Japan and Southwest Jiaotong University, China are
making collaboration in a joint project NSJP for constructing a new stellarator CFQS in China.
The device design concept is based on the quasi-axisymmetric advanced stellarator. As well
as good performances of confinement properties of core region, the magnetic configuration
of the peripheral region is very important because the diverter performance is crucial for the
successful achievement of the future reactor design. For the present stellarator experiments,
two leading concepts for the divertor are well known, namely, the intrinsic helical diverter,
represented by LHD in Japan, and the island diverter represented by W7-X in Germany.
For the new stellarator CFQS, we propose a new diverter concept of “Island Bundle Diver-
tor (IBD)”. Since the diverter magnetic configuration of IBD is constructed with magnetic
island structure, there is a similarity between IBD and the island diverter in W7-X. However
the essential difference is a very large size of the islands surrounding the core region, which
clearly define two separate confinement regions of core confinement and divertor region
(Fig.1). These two regions are facing with each other through a clearly defined magnetic
separatrix. Divertor field line tracing pattern shown in Fig. 2 is similar to the tokamak divertor
and the connection length of field lines between the separatrix and the divertor wall is long
enough (without exceptional short lines) for the good divertor performance.
Fig. 2 Divertor tracing with vacuum
Fig. 1 Magnetic surfaces of Island Bundle chamber wall in blue
Divertor
