JET disruption mitigation and avoidance in support of DT operation and ITER

JET is starting a multi-campaign effort that will lead in 2020 to the first experiments in D-T mixtures since 1997. While intense experimentation is going on in order to prepare the operational scenarios and physics bases for DT operation, an important part of the JET programme is devoted to disruption avoidance, minimizing the possible damage to the machine during DT campaigns, as well as to disruption mitigation studies with the Shattered Pellet Injector (SPI) in support of ITER. The effectiveness of SPI in radiating disruptions thermal load on plasma facing components has been modelled for the first time using the 3D non-linear MHD code JOREK, and the predictions will be possibly validated on first JET SPI data and compared with results obtained with massive gas injection (MGI). A particular effort has been devoted to the optimization of bolometry and SXR tomographic inversion techniques in order to identify toroidal and poloidal radiation asymmetries that had been found with single MGI mitigation. The Electro Magnetic load on the JET vacuum vessel has been modelled using 3D MHD codes, yielding to a reduction of 30-40% in vessel forces in case of MGI mitigated disruptions, with good agreement with JET experimental data. Special focus has been put on runaway electrons (RE) physics, mitigation and Real Time (RT) control in support of ITER Disruption Mitigation System (DMS) design. Several diagnostic upgrades have been carried out in order to diagnose the RE beam energy and position, gamma ray tomography and hard X-ray detectors, while a bespoke RT detection algorithm has been developed to control the RE beam position and current. The diagnostic effort has been coupled with numerical assessment of RE formation condition and modelling of gas penetration from MGI....