Recent results and future plan on JT-60U

Recently, JT-60U has intensively addressed enhancement and long sustainment of steady state performance in the use of negative-ion based neutral beam injection (N-NBI) and electron cyclotron (EC) wave injection. The N-NBI increased the current drive efficiency up to 1.55×10¹⁹ A/m²/W at 360 keV and enhanced the fusion triple product up to n_i(0)τ_ET_l(0)∼3.0×10²⁰ keV sm^-3 during, a full current drive condition. Increasing the plasma triangularity extended the duration of a plasma with β_N∼2.7 up to ∼60 τ_E. The EC heating in combination with lower hybrid wave injection produced a very high electron temperature of ∼26 keV for a reversed shear plasma. For reversed shear plasmas, the formation and sustainment of a central current hole was also discovered. High-field-side pellet injection extended the confinement up to H_89p∼2 at n/n_G∼0.7. For the modification of JT-60, a fully superconducting tokamak, JT-60SC, is planned to further economical and environmental attractiveness in a tokamak DEMO reactor. The mission of JT-60SC is to realize high performance steady state operation and demonstrate the plasma applicability of low activation material for a plasma of break-even class relevant to the reactor plasma. Physics issues, design and machine description for JT-60SC with I_p=4 MA, B_t=3.8 T and R_p=2.8 in are outlined.