Implementation and performance evaluation of the real-time algorithms for Wendelstein 7-X divertor protection system for OP2.1

A new Infrared (IR) image analysis system will be deployed for real-time divertor protection during the upcoming Operational Phase (OP) 2.1 in the Wendelstein 7-X (W7-X) stellarator. Its primary objective is to prevent thermal overloads from permanently damaging Plasma-Facing Components (PFCs), resulting in machine downtimes and repair costs. The real-time constraint for this system is 110 ms, which is the maximum allowed delay entailing the acquisition, calibration, processing, and interlock, while all processing steps have to complete within 10 ms allowing for processing longer than the acquisition time of 10 ms at 100 Hz. This paper describes the implementation, real-time processing performance and detection effectiveness of Thermal Overload Detection (TOD). The implemented and evaluated TOD system fulfils real-time constraints. It reduces the total system delay to 50 ms and provides high detection sensitivity of 0.97 for archived discharge sequences from the OP1.2 campaign. The attained acceleration is significant, i.e., a 95% and 99% decrease in runtime for the sequential Central Processing Unit (CPU) and parallel Graphics Processing Unit (GPU) implementations, respectively, compared to the initial Python prototype. For the first time, the presented results confirm the feasibility of protecting W7-X in real-time comprising fundamentals for further advanced protection and control.