Core transport modelling of the DTT full power scenario using different fuelling strategies

Abstract

A theory-based integrated modelling work of plasma response to deuterium fuelling in the new Divertor Tokamak Test facility (DTT) is performed, using the transport code JETTO with the quasi-linear anomalous transport model QuaLiKiz for the core region. The full power DTT scenario E1 is investigated. It is characterized by 28.8 MW of Electron Cyclotron Resonance Heating (ECRH), 10 MW of Neutral Beam Injection and 6 MW of Ion Cyclotron Resonance Heating to the plasma. Plasma density and temperature profile evolution is calculated using two different fuelling methods, gas puffing and pellet injection, and two different seeding gases, argon and neon. With gas puffing the neutral flux at the separatrix needed to sustain the desired pedestal density level exceeds the feasibility limits of the pumping system, regardless of the type of impurity introduced, thus making the use of pellets mandatory. The simulations performed with pellet injection as fuelling method predict that the pedestal density is well sustained with realistic parameters foreseen for the DTT pellet injector. Strong dependence of the core density on the EC power deposition profile is found. TEM dominance, low outward flux and strongly hollow density in the inner core region are foreseen with central peaked EC power deposition profile. ITG dominance, inward flux and robust density sustainment on the whole radial interval are predicted for spread EC power deposition, though with central density close to the EC limit and with peaked impurity densities. An intermediate deposition extension is found to sustain the whole density profile and to obtain flatter core densities, as previously predicted for the reference full power DTT scenario by fixed pedestal simulations. The EC deposition is negligibly modified by refraction changes both during a single pellet cycle and after several pellet cycles, indicating full compatibility between the EC system and the pellet injection system.