Is an operation scenario for CS-less current ramp-up to steady-state burning feasible? Steady-state operation of high-beta /low aspect ratio tokamak reactor with bootstrap current

Recent spherical tokamak (ST) experiments exhibit many advantageous results including plasma start-up without center solenoid, higher fraction of non-inductive current, and formation of internal transport-barrier as seen on conventional tokamak. In order to reflect these efforts to the design of a so-called ''current ramp-up scenario'' and ''non-inductive steady-state (SS) operation scenario ''of low aspect-ratio tokamak, fractions of bootstrap current and neutral-beam-driven current on a low-aspect-reactor, VECTOR-OPT, are estimated. The operation with such a SS scenario is shown to be feasible if the normalized plasma beta is raised larger than 5, which is typical in ST, with a broader pressure profile. (author)