The optimized l_i advanced tokamak scenario with high bootstrap current fraction

Equilibrium and stability analyses have identified a class of tokamak configurations with conventional safety factor profiles (q₀∼q_min≳1) at moderately high l_i(l_i∼1.0), and high normalized β(β_N∼3.5-4.0), that are stable to the ideal n = 1 kink without the requirement of wall stabilization. In contrast to previously identified high l_i, high β_N equilibria, these configurations have high bootstrap current fractions (f_BS∼50%-70%); they require only modest central current drive for maintaining steady state and are therefore compatible with advanced tokamak (AT) operation. Strong plasma shaping is crucial for achieving the high β and high bootstrap fraction simultaneously.