Scrape-Off Layer opacity to D and T gas puff fuelling in JET baseline scenario

Determining the particle sources within the separatrix is crucial for understanding the fuelling efficiency of fusion devices. Particle sources from Neutral Beam Injection (NBI) and pellets can be confidently assessed through modelling and experimental measurements, whereas those from gas puff injections remain challenging to determine in present experiments, and often are not measured (e.g. at JET). Experimental observations of the baseline pulses performed at JET indicate different behaviours for deuterium (D) and tritium (T), influenced by the opacity of the Scrape-Off Layer (SOL) and the diffusion of these elements into the separatrix due to their distinct neutral dynamics. This study investigates the SOL opacity for different D and T fuelling levels in JET (DTE2) baseline plasmas through Core-SOL integrated modelling, using the JINTRAC [1] suite of codes equipped with the semiempirical Bohm/gyro-Bohm transport model [2]. The experimental overview of the pulses analysed in this work can be find in [3]. The simulation settings are briefly presented in section 2, while the modelling results of a core-SOL coupled simulation for the Deuterium pulse (JPN 96482) and the Tritium one (JPN 99282) are presented in section 3. The nominal gas rate is then varied to evaluate the SOL opacity and the gas puff fuelling efficiency to different gas puff levels, at first in steps (Sec. 3) and then in linear ramps with different ramp velocities (Sec. 4)