Creating stable tokamak reactor equilibria by supplemental heating

It is shown that temperature-dependent supplemental heating can be used to prevent thermal runaway in a tokamak reactor by creating stable equilibria at desired operating points with temperatures below ignition. HFCTR is used as an example, and it is shown that large Q (>20) can be obtained at modest temperatures (< 13 keV) by using power inputs of the order of 3–30 MW. The effect of thermal fluctuations is addressed, and it is shown that a control time delay of ∼ 0.5 – 1.5 s can still maintain stable operation.