Preliminary Modeling of Disruption Plasma Scenario in View of a Shattered Pellet Injection in DTT Machine

Vertical displacement events (VDEs) are among the most dangerous types of disruptions that can take place in a tokamak. They cause a fast release of both thermal and electromagnetic (EM) energy on the plasma-facing components, also inducing eddy and halo currents in the passive components touched by the relatively cold plasma. In the high EM field, these may result in enormous, localized loads. To reduce the impact of disruptions on the structures adjacent the plasma, a disruption mitigation system (DMS) is needed. In this frame, the Divertor Tokamak Test (DTT), which is being built in Frascati (Italy) and is designed to test different divertor solutions for DEMO and ITER, has been proposed to be equipped with a shattered pellet injection (SPI) system as the main DMS. Here, the initial design of DTT SPI and preliminary predictive disruptive plasma scenarios, simulated by the MAXFEA code, will be discussed. A detailed disruption database will be presented, built with a methodological approach. For a single-null configuration, the reference DTT parameters include a plasma current I_pla of 5.5 MA and a magnetic field B_t of 5.85 T, with major radius R and minor radius a of 2.19 and 0.7 m, respectively. In this case, i.e. an unmitigated disruption scenario, the forces acting on the vacuum vessel may reach up to −10.6 MN. Although the structural integrity of DTT is guaranteed under these EM loads, reducing them is recommended in the case of extensive campaigns of disruption studies. Therefore, mitigated ones will be discussed in this work. The current and integral EM forces induced during unmitigated and mitigated disruptions will be compared to give a preliminary evaluation of the effects of VDEs on the tokamak components in view of the DTT SPI system design.