Recent progress and future prospects of the JT-60 program

Recent results from JT-60U on high performance and steady-state experiments are presented. High fusion performance of n/sub D/(0)/spl tau//sub E/T/sub i/(0)=1.1/spl times/10/sup 21/ m/sup -3//spl middot/s/spl middot/keV, Q/sub DT//spl sim/0.6, S/sub n/=5.6/spl times/10/sup 16/ s/sup -1/ has been obtained in the regime named "High-/spl beta//sub p/ H-mode". A total plasma pressure has achieved /spl sim/0.12 MPa and a bootstrap current has reached /spl sim/1 MA in these high fusion performance plasmas. Optimization of current profile and heat deposition profile has substantially extended attainable /spl beta//sub N/ and /spl beta//sub p/ values, reaching 4.0 and 4.3, respectively. In a quasi steady state of ELMy H-mode, /spl beta//sub N//spl sim/3, /spl beta//sub p//spl sim/3 and H-factor/spl sim/2.2 was sustained under the full current drive condition (bootstrap current /spl sim/50%, beam driven current /spl sim/50% at Ip=0.5 MA). In addition, driven current of 3.6 MA has been obtained by lower hybrid wave, and the capability of LH and NB as active current driver was demonstrated. Experiments show high safety factor is attractive to obtain high plasma performance. Also described are the future plan of a new 500 keV negative ion beam system and a proposal of further modification of JT-60U named "JT-60 Super Upgrade". JT-60 Super Upgrade aims to establish an integrated basis of physics and technology for steady-state tokamak reactors like SSTR.