Overview of the JET last D-T results in support of ITER and the reactor*

Before ending operation at the end of 2023, JET has returned to a deuterium-tritium operation (the DTE3 campaign) [1]. DTE3 was focused on developing high radiative scenarios for ITER and DEMO, integrating in-depth physics understanding done in the previous 2022-2023 deuterium campaigns [2] and apply novel control schemes in DT mix regimes.

In DTE3, the operational space of the Ne-seeded ITER baseline scenario [3] was extended in D-T to high current (3.0-3.2MA) in high performance plasmas and partially detached regime. Peeling limited pedestal at low collisionality [4] have been studied with different isotope mix and screening effect by temperature gradient at the plasma edge [5] has been validated in a broad range of the parameter space.

The compatibility of the QCE small-ELMs regime [6] with D-T operation was also demonstrated in near double null. In addition, the X-point radiation regime [7] was successfully accessed in D-T in real time using reactor relevant diagnostics. Other control schemes were developed for the isotope mix with gas and pellets. Tritium retention was investigated with gas-balance techniques and with a novel laser based technique [8], validating for the first time an in-situ fuel retention diagnostic method. Based on the DTE2 analyses [9], the reproducibility of sustained high fusion power production has also been proven. Finally, DTE3 was followed by a cleaning-up campaign that successfully characterized the tritium decay in the vessel.