Large Current Drive Experiments Using Simplified Multijunction Lower Hybrid Wave Launcher in JT-60U

A newly developed multijunction launcher for lower hybrid current drive (LHCD) experiments has demonstrated the largest driven current (3.6MA) in the world and a very high current drive efficiency (ηCD=neRpICD/PLH=3.5×1019m-2·A/W). This launcher has a good current drive capability, and may simplify largely an LHCD launcher in a steady state tokamak reactor. Experiments performed by this launcher have expanded the experimental database on LHCD widely, and show that a higher current drive efficiency and a flatter driven current profile have been observed at a higher driven current.