Feasibility study for very high aspect ratio tokamak fusion reactor

Very high aspect ratio (A) tokamak reactor is proposed as a future power plant. Plasma size and operation performance are surveyed over a wide range of A. To reduce the plasma minor radius, relatively high toroidal magnetic field of 18T is adopted. When the plasma major and minor radii are 12 m and 1.5 m (A=8), steady-state operation with 3 GW of fusion power and large fusion gain (>40) is possible. 90% of bootstrap current fraction is achieved by optimizing the density profile for the given MHD equilibrium. Toroidal field (TF) coil size is estimated by considering the field ripple, NBI beam line and coil case stress. Although overall TF-coil height and width are smaller than those of ITER, cross-sectional area of the TF-coil leg becomes 4 times larger than that of ITER to compensate the vertical force. (author)