Progress in the Divertor Tokamak Test facility physics design

DTT is a superconducting tokamak with 6 T on-axis maximum toroidal magnetic field carrying plasma current up to 5.5 MA in pulses with total length up to 100 s. DTT is a divertor facility designed to accommodate a variety of divertor configurations and the auxiliary heating power coupled to the plasma at maximum performance is 45 MW. This allows matching the PSEP/R values with those of ITER and DEMO, where PSEP is the power flowing through the last closed magnetic surface. In the last eighteen months the design has progressed steadily, the legal entity for the DTT construction has been established, the budget has been closed and the first large procurement (superconducting strand) has been assigned. This paper reports the recent results of the activity dedicated to improve and finalize the physics design of the experiment. In particular we will describe the integrated modeling of various plasma scenarios inside the separatrix done with the JINTRAC suite of codes and by calculating the pedestal pressure with EPED1 (Europed code). The pedestal density is set to achieve a volume averaged density ~ 0.43 nGW. . The region inside the top of the pedestal is modeled with QuaLiKiz or TGLF quasilinear transport models and with NCLASS or NEO for neoclassical transport. Core Te peaks at values above Ti due to strong central ECRH and stiff ion heat transport. Density profile is moderately peaked with central density ~ 2´1020m-3 . Fast-ion losses due to trapped-precession resonance are estimated with the code ORBIT. The LFS magnetic ripple of the reference SN scenario (?B/B~0.42% ) gives a small contribution, with up to 0.5% collisionless particle loss in the first ~1000 toroidal transits. Initial ion positions and pitch are calculated with METIS, using full heating scenarios with NNBI ranging between 400 keV and 600 keV. The simulation of DTT MHD stability will be discussed. DTT high level of flexibility, in particular as far as divertor scenarios are concerned, is granted from a magnetic point of view by a set of external and internal coils. They allow to control and optimize the local magnetic configuration in the vicinity of the divertor target. Simulations of several divertor configurations, also implemented in negative triangularity scenarios, will be presented.