Steady-state operation of high-beta/low aspect ratio tokamak reactor with bootstrap current

Sengoku, Seio

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