Plasma real-time control system for advanced tokamak operation scenarios in JT-60

Tokamak magnetic fusion research has progressed to an advanced project, i.e., ITER (International Thermonuclear Experimental Reactor). Therefore, existing tokamaks must explore operational scenarios necessary for a high-performance plasma while simultaneously suppressing any disruptive instabilities. To implement this investigation, various advanced real-time controls using processed profile data and all available actuators should be tested in the experiments. To satisfy these requirements at the large tokamak JT-60, we are upgrading its original real-time control system completely. Two criteria for the new system configuration have been adopted: (i) The distributed processors for the measurements, actuators, and supervisory controllers (SVCs) am linked through a "reflective memory (RM)" network for fast, real-time communication. The profile data in the RM modules are also updated in real time. (ii) For efficient parallel and pipeline processes performed by multiple controllers, synchronization is provided from two sources: external hardware clocks and software counters in the RMS, which are updated by the SVCs. For a control function, the following simple and flexible method has been employed to perform various experimental proposals: New test control methods are first registered in the supervisory controllers. In accordance with the preprogrammed waveforms that indicate which control method to use, the SVCs select the correct control method in real time. The upgraded configuration of the JT-60 plasma control system and its effectiveness in seeking advanced operational scenarios applicable to ITER are discussed in detail.