Review on the progress of the LHD experiment
Recent progress in the Large Helical Device (LHD) experiment during the last 2 yr is reviewed. The LHD has been extending its operational regime toward fusion-relevant conditions while taking advantage of the net-current-free heliotron concept employing a superconducting coil system. Heating capability has exceeded 10 MW, and the central ion and electron temperatures have reached 7 and 10 keV respectively. The maximum values of beta and pulse length have been extended to 3.2% and 150 s, respectively. Several encouraging physics observations have been obtained, i.e., simultaneous achievement of the mitigation of the magnetohydro-dynamic instability criteria and good confinement, and formation of an internal transport barrier. The initial results have been obtained using a local island divertor, which shows the possibility of particle control at the plasma edge.