Configuration Optimization of a Planar-Axis Stellarator with a Reduced Shafranov Shift

Magnetic configurations of LHD experiment are analyzed based on the Fourier modes of the plasma boundary shapes. It was found that a small number of Fourier modes is sufficient to determine the confinement characteristics of different configurations with the magnetic axis shift of LHD. A new configuration is proposed with adifferent combination of Fourier modes, which has good particle orbits and a favorable property of high beta equilibrium. This solution has a smaller Shafranov shift than the inward-shifted configuration of LHD.