Plasma modeling for optimized design of FAST, a fusion energy systems integration test facility

This paper presents the outline of the plasma modelling for optimized design of the tokamak device for the FAST (Fusion by Advanced Superconducting Tokamak) project. In FAST, DT fusion power of ~50 MW is planned to be sustained in plasma discharges with pulse length of 1000 sec. The design of FAST is optimized to minimize the size and cost to achieve this goal. The following conditions/requirements are considered; a) the full non-inductive current drive operation, b) minimum central solenoid, c) external heating power of less than 60 MW, and d) use of high temperature superconductor. In the plasma modeling or physics aspects, the following features are essential; (i) determining the heating and current-drive actuators for achieving the fully non-inductive operations, including the current ramp-up phase, and also the enhancement of the fusion power with beam-thermal fusion reactions, (ii) determining the operational density considering the externally driven current, the bootstrap current, energy confinement and thermal / non-thermal fusion powers and (iii) control of DT ratio under large D fueling with NB. One possible set of parameters found so far is: the plasma major radius of 2.78 m, the plasma minor radius of 0.95 m, elongation of 1.8, the plasma current of 7.1 MA and the magnetic field at the plasma center of 4.9 T. With injection of 32.6 MW of N-NB (500 keV, D) and 12 MW of EC, the DT fusion power of 48.5 MW would be obtained under the full non-inductive operation. The assumed H_98y2 is 1.2 and the normalized beta is 2.6.