NONINDUCTIVELY CURRENT-DRIVEN H-MODE WITH HIGH BETA(N)-VALUES AND HIGH BETA(P)-VALUES IN JT-60U

Attainable beta(p) and beta(N) values were widely improved in JT-60U by peaking of the current profile and broadening of the pressure profile. In a quasi-steady state of ELMy H mode, beta(p) similar to 2.5-3, beta(N) similar to 2.5-3.1 and H factor similar to 1.8-2.2 were sustained for similar to 1 s simultaneously under the full current drive condition (bootstrap current 60%, beam driven current 48% at I-p = 0.5 MA). In a transient case, the maximum values of beta(p), epsilon beta(p) and beta(N) reached 4.7, 1.2 and 4.2, respectively. The achievable beta(p) value increases systematically with safety factor at the edge. To obtain these improved high beta plasmas, it is essential to control MHD activities; suppression of beta(p) collapse and medium m/n (poloidal mode number/toroidal mode number) modes by the modification in current and pressure profiles and control of ELM activity by suitable selection of the heating power.