General purpose architecture for real-time feedback control in nuclear fusion experiments

In magnetic confined nuclear fusion experiments, active feedback control systems are used to control global plasma parameters such as the plasma position and shape. Active control is also used to enhance the plasma confinement by controlling local perturbations of the magnetic configuration. Feedback controls which act on global plasma parameters may use up to hundreds of inputs and require response time to control phenomena which evolve with time constants from tens to hundreds of ms, while controls acting on local parameters generally use fewer input signals but require response time of hundreds of μs. The paper presents the concepts and the design of a general purpose distributed architecture for computer based real time feedback control in nuclear fusion experiments, along with the Petri net based formal model used to assess the behaviour of the system and to predict its performance. The architecture has been implemented in the feedback control system of the RFX experiment, one of the large devices in the framework of the European Programme on nuclear fusion