Operation of a lithium beam diagnostic in tritium and deuterium-tritium experiments at JET
A fast neutral lithium beam is used at JET for more than 30 years to measure profiles of electron density in the pedestal and scrape off layer. The diagnostic was not designed for tritium operation. In this paper, we describe the modifications which were required to allow operation in tritium (T) and deuterium-tritium (D-T ) fuelled pulses at JET in 2021 and 2023. We had to install methods to remote control the diagnostic setup. The vacuum pump and exhaust system had to be made tritium compatible, radiation vulnerable electronics had to be removed from the torus hall. The observation system relied on regular in vessel mirror exchange. We designed and installed an in-vessel protection shield close to the observation mirror to reduce damage to the mirror surface. We comment on operation in T and D-T discharges and maintenance post tritium exposure and calibration of the system.