MINIMUM SIZE Q=1 AND IGNITED SPHERICAL TOKAMAK DEVICES

We find minimum sized Spherical Tokamak (ST) configurations capable of Q similar to 1 (scientific break-even) and ignition. For Q similar to 1 cases, we normalize our models to the JET device. We find comparabl e plasma power balance performance in an ST configuration of major rad ius similar to 0.7 m, using both global and 3/2 D plasma transport mod eling. For ignited plasma, we first normalize the plasma modeling to t he ITER device. We find similar ignited plasma performance capabilitie s in an ST configuration of major radius 1.2 m. These are much smaller size plasmas than the standard tokamak counterparts, indicating a pot entially easier path towards commercial applications. Also, we find th at the quantity IA is not a good figure-of-merit for comparing perform ance of widely different tokamak configurations.