Post-disruptive shift of magnetic axis in non-circular tokamaks

The magnitude of magnetic-axis shift, following a sudden, disruptive decrease in internal inductance and poloidal β, can be greatly reduced in non-circular tokamaks by exploiting the negative decay index of the equilibrium magnetic field. In thise sense, a non-circular plasma has important advantages over a circular plasma in preventing the catastrophic consequences of major disruptions. A tokamak design and operational concept is discussed, which exploits these advantages and is fundamentally different from the traditional approach.