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Institute of Information Sciences and Electronics,
University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8573, Japan
A. Kamitani
Department of Electrical and Information Engineering, Faculty of
Engineering, Yamagata University, Johnan 4-3-16, Yonezawa, Yamagata 992-8510,
Japan
Abstract. In the HIST device, the external flux is generated by two kinds
of currents: the current
Is flowing along the symmetry axis and
the bias coil current
ID. The influence of the external flux on
the MHD equilibrium and stability of the low-aspect-ratio toroidal plasma in
the HIST device is investigated numerically. Equilibrium configurations of the
low-aspect-ratio toroidal plasma in the HIST device are numerically determined
by means of the combination of FDM and BEM. The influence of
Is
and
ID on their stability is also investigated by using the
Mercier criterion. The results of computations show that the Mercier limit
decreases to zero with increasing
Is and with decreasing
ID. Moreover, either a further increase in
Is or a
further decrease in
ID raises the Mercier limit
considerably. Besides, the equilibrium configuration in the HIST device
changes its state from spheromak through ultra-low q to tokamak
with increasing
Is and with decreasing
ID.
IAEA 2001
