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Abstract. The design requirements for helical reactors are investigated on plasma confinement, density regime and beta limit, comparing with recent LHD (Large Helical Device) experimental data. Several new confinement scaling laws are derived using LHD database in addition to the medium-sized helical system database. In the previous reactor designs two times better plasma confinement than the conventional LHD scaling law was assumed, which has been achieved experimentally as ``New LHD'' scaling laws. One and half times higher density than the conventional helical density limit scaling laws has been achieved, which condition is required at the start-up phase of reactors. Half of beta value required in reactors is achieved in the inward-shifted configuration in LHD experiment, which value is beyond the theoretical stability limit. This magnetic configuration satisfies the high beta and low effective helical ripple operation required for reactors. Almost these normalized requisites have been achieved in the LHD experiment Based on new LHD scaling laws the reactor system design has been carried out. The COE (cost of electricity) value of large reactor system is not so high in comparison with that of compact design, however the compact reactor has advantage of rather lower direct cost. The present LHD experiment can justify the future prospect of the LHD-type helical devices towards a steady-state efficient and reliable reactor.
IAEA 2001
