WEST operation with real time feed back control based on wall component temperature toward machine protection in a steady state tungsten environment

TL;DR

This paper presents a real-time wall temperature monitoring and feedback control system for the WEST tokamak, improving plasma operation safety and enabling higher power discharges by protecting wall components.

Contribution

It introduces a real-time wall monitoring system integrated with plasma control, effectively managing wall temperatures and reducing risks during high-power operations.

Findings

Maintains wall temperature within safe limits 97% of the time

Activates feedback control in 14% of plasma discharges

False positive rate of 0.2% for wall temperature alarms

Abstract

A real time Wall Monitoring System (WMS) is used on the WEST tokamak during the C4 experimental campaign. The WMS uses the wall surface temperatures from 6 fields of view of the Infrared viewing system. It extracts the raw digital data from selected areas, converts it to temperatures using the calibration and write it on the shared memory network being used by the Plasma Control System (PCS). The PCS feeds back to actuators, namely the injected power from 5 antennae's of the lower hybrid and ion cyclotron resonance radiofrequency (RF) heating systems. WMS activates feed back control 63 times during C4, which is 14% of the plasma discharges. It activates mainly as the result of a direct RF loss to the upper divertor pipes. The feedback control maintains the wall temperature within the operation envelope during 97% of the occurrences, while enabling plasma discharge continuation. The false positive rate establishes at 0.2%. WMS significantly facilitated the operation path to high power operation during C4, by managing the technical risks to critical wall components.