JET Program for Closing Gaps to Fusion Energy

The European program foresees that a pure tritium (T-T) and an extended deuterium-tritium (D-T) experimental campaign will be carried on Joint European Torus (JET). The realization of the JET T-T and D-T experimental campaigns is an important contribution to fill major physics and technological gaps for the development of fusion energy. The JET-ITER-like wall experiment provides an ideal test bed to study in an integrated way the interplay between the plasma surface interactions and the plasma operation with the ITER plasma-facing materials (beryllium wall and tungsten divertor). Recent and significant progresses of the ITER scenarios development on JET are reviewed together with their extrapolation by assuming a 50%-50% D-T plasma mixture. The JET performance has been recovered at a plasma current up to 2.5 MA for both the ITER baseline and the hybrid scenarios. These two scenarios will be pursued at higher fusion performance by increasing the applied powers and/or plasma current in the coming experimental campaign in the conditions compatible with the W-divertor. The D-T experimental campaign will provide a unique opportunity to benchmark the ITER relevant 14-MeV neutron detection calibration procedures, neutronic codes for calculating the neutron flux, and machine activation, and to investigate the radiation damage of ITER functional materials. In view of the full tritium and D-T experimental campaigns, the JET tritium plant is being upgraded with an increase in the T-fuelling capability using different gas injection modules, with an improved T-accountancy and a new water detritiation system to fully close the T-cycle at JET.