Real-Time Diagnostics and Their Applications at ASDEX Upgrade

For applications of advanced plasma control schemes, many computers that execute complex algorithms need to communicate with low latency so that result data are promptly available for operating adequate actuators that can directly influence the plasma behavior. ASDEX Upgrade has completed the commissioning phase of its real-time diagnostic framework serving that purpose. Several applications were successfully tested, and progress toward a full feedback neoclassical tearing mode stabilization loop is evident. The new real-time diagnostics comprise several new diagnostics capable of acquiring raw data (up to 1 MHz, up to 60 channels), processing the raw data (calibrate, transform, evaluate, etc.) and transmitting the results over suitable networks to other computers, all in real time. Projects for machine safety (divertor cooling and hot spot detection), physics studies [regulation of density peaking by application of electron cyclotron resonance heating (ECRH)], and real-time state monitors (ECRH deposition calculation) have demonstrated the capabilities of the new diagnostics and the control framework. The control system can now operate its actuators in line with decisions based on algorithms with rather high complexity. Adding new control algorithms has become a distributed effort with manageable overhead.