# Real-Time Detection of Overloads on the Plasma-Facing Components of Wendelstein 7-X
## 6 Conclusions  
The protection of W7-X during steady-state plasmas requires checking in real-time the temperature of the PFCs against their limits, and triggering an alarm to the interlock and interrupt operation when these limits are compromised. Rather than using a fixed temperature threshold for each PFC and react when these thresholds are breached, a predictive algorithm sets a dynamic threshold in real-time for each pixel based on the different temperature limits and current heat-flux distribution. This dynamic threshold determines the estimated risk of overload during the processing time and it allows to trigger the alarm in advance to compensate for the delay in the system. Figure 13: The machine is protected with a dual detection scheme. The Thermal Overload Detection algorithm detects when a PFC has risk of overloading and triggers the interlock to stop operation. The Thermal Event Detection algorithm promptly detects the thermal events, tracks them over time, classifies them and computes their risk. It sends all this information to the feedback control system. When an event reaches a certain risk, the feedback control has to take action to prevent the overloading of the PFCs and the plasma interruption. In this design, we avoid the use of regions of interest to monitor the different incussel components with different temperature limits. Instead, a scene model provides a pixel-wise correspondence of the entire field of view with the CAD model of the PFCs and their properties, such as emissivity and temperature limits. The scene model is constructed automatically by code and the operator does not need to know the position of each component and their limits. When the in-vessel components are changed, the scene models are updated automatically. The risk images encode the temperature limits of the different components, and the detection of overloads is performed naturally instead of treating each region of interest separately. This is useful when an event affects several components with different operational limits. An example of this is when a strike-line extends from the divertor targets towards the baffles. We could validate the Thermal Overload Detection algorithm with the data acquired during the OP1.2 campaign when we used an uncooled test divertor. The results show the algorithm can detect all the safety-relevant thermal events that we manually observed during the campaign with enough anticipation time to compensate for the system delay. This proofs that the system would have promptly interrupted operation had it been connected to the interlock. The test of the algorithm with an uncooled divertor can be translated to a water-cooled divertor in non-steady-state conditions when an overload can occur. Therefore, the system is ready for commissioning and to provide a safe machine operation in the next campaign, when water-cooled PFCs will be used. To achieve high-performance steady-state operation, however, it is also required to avoid most of the plasma interruptions through the feedback control. We envisage a PFCs protection system based on a dual detection scheme. The Thermal Overload Detection algorithm will protect the device using real-time image-processing techniques, while the Thermal Event Detection algorithm will use more advanced machine learning to detect, track and classify the different thermal events. The first provides high reliability aimed at machine protection and the latter allows a higher level of scene understanding, paving the way for a future feedback control of the thermal loads. Conceptualization, A.P.S., M.J., D.N., J.R.C. and P.S. ; Data curation, A.P.S., Y.G., P.D., H.N. and J.F. ; Formal analysis, A.P.S. ; Funding acquisition, M.J. and R.M. ; Investigation, A.P.S. ; Project administration, A.P.S., M.J., R.M. and A.W. ; Resources, M.J., R.M. and A.W. ; Software, A.P.S., Y.G., V.M., F.P., C.B., M.-H.A., P.S., R.C., S.F., H.L., T.B. and K.B. ; Supervision, A.P.S., M.J., R.M., B.C., J.R.C., P.S. and A.W. ; Validation, A.P.S. ; Visualization, A.P.S. ; Writing--original draft, A.P.S.