Robust Burn Control of Fusion Reactors with Modulation of Refueling Rate

An integrated 0-dimensional plasma-control code, ASH, has been developed and employed to study the possibility of controlling the burn condition of an ITER-type fusion reactor by modulating the refueling rate. A key feature of this study is the incorporation of robust control theory to allow for modeling uncertainties. A constant gain proportional feedback controller is synthesized; the values of feedback gains are obtained by the H∞ algorithm. With this control method, modulation of the refueling rate alone can potentially stabilize fusion burn with the alpha confinement time τ*α = 11τE, or controller delay τdelay = 1.5τE, or D-T recycling ratio 98%. These limitations are fairly restrictive, indicating that added control, e.g., via input power modulation, may be necessary.