Multi-Input Multi-Output (MIMO) control system with a state equation for fusion reactors

In future fusion reactors, plasma control can be anticipated to be quite complicated because actuators and diagnostics would be limited because of extreme environmental conditions, such as high neutron fluxes. In addition, control parameters and actuators are not in simple one-to-one correspondences (e.g., NBI power affects not only plasma current but also fusion power). This results in the need of using multi-input multi-output control systems. To confront this problem, we have developed a control system design that involves an state equation. In this research, simulations were performed in which three plasma parameters (fusion power, plasma current, and plasma density) were controlled using three actuators (NBI power, amount of gas puff, and inductively driven current). Parameters for these actuators were determined from the state equation, and the plasma parameters were simultaneously controlled with sufficiently high accuracy. (author)