Design of the Korea Superconducting Tokamak Advanced Research (KSTAR)

The KSTAR team is carrying out the design and research and development for a steady-state-capable advanced superconducting tokamak to establish the basis for an attractive fusion reactor as a future energy source. The physics requirements are driven by the plasma control and exhaust capabilities needed to extend the performance and pulse length of tokamak plasmas. The tokamak has major radius 1.8 m, minor radius 0.5 m, toroidal field 3.5 T and plasma current 2 MA, a strongly shaped plasma cross-section shaping (elongation 2.0 and triangularity 0.8), and a double-null poloidal divertor. The initial pulse length is 20 s, long enough to study physics on confinement timescales, but short enough to permit economical plasma-facing component technology. The pulse length can be increased to 300 s through upgrades. The machine will be operable in either hydrogen or deuterium, but neutron yields will be constrained to avoid the cost and inconvenience of remote maintenance and low-activation materials. The magnet system provides an inductively driven 20 s pulse with full current, beta, and shaping. With non-inductive current drive, steady-state plasmas can be sustained over a wide range of profile shapes and plasma pressures. Passive structures are provided to stabilize the vertical instability and high-beta modes and internal coils are provided for fast position control. The divertor structures are designed for particle removal, recycling control, impurity control, and flexibility for advanced divertor operation. The plasma heating system is designed for heating, current-drive, profile control, and flexibility. It will deliver power via neutral beams (8 MW), ion-cyclotron waves (6 MW), and lower-hybrid waves (1.5 MW), each of which can be expanded through upgrades. A comprehensive set of diagnostics is planned for plasma control, performance evaluation, and physics understanding.