Computational Study of MHD Equilibrium of Noncircular Tokamak Reactor Plasmas

The MHD equilibrium and stability of noncircular tokamak plasmas limited by a separatrix is studied for reactor size systems. A typical example with a plasma current of 15.8 MA and major radius of 8.1 is presented. The required vertical field is generated by a set of discrete external coils and no conducting shell is included. The detailed equilibrium shape is calculated numerically for a vertical elongated plasma with two stagnation points symmetrically located above and below the midplane as would be required for a system with a poloidal divertor. The plasma height to width ratio is 2, the plasma shape factor is 1.6 and poloidal ß is 2.2. The plasma is locally stable. The general stability criteria with respect to quasi-rigid motions (special kink modes) are calculated numerically and found to be satisfied. Size scaling and the engineering constraints are discussed.