Prediction of divertor heat flux width for ITER scenarios using BOUT++ transport code *

Prediction of divertor heat flux width is performed for the first and the second Pre-Fusion Power Operation (PFPO) phases specified in the new ITER Research Plan and ITER baseline L-mode scenario using BOUT++ transport code. The initial plasma profiles inside the separatrix are taken from CORSICA scenario studies. Transport coefficients in transport code are calculated by inverting the plasma profiles inside the separatrix and are assumed to be constants in scrape-off-layer (SOL). An anomalous thermal diffusivity scan is performed with E×B and magnetic drifts. The results in both scenarios identify two distinct regimes: a drift dominant regime when diffusivity is smaller than the respective critical diffusivity  and a turbulence dominant regime when diffusivity is larger than it. The critical diffusivity is 0.5 m$^{2}$/s in 5MA PFPO-I scenario, 0.3 m$^{2}$/s in 7.5MA PFPO-II scenario and 0.005 m$^{2}$/s in 15MA L-mode scenario. The ITPA multi-machine experimental scaling yields a lower limit of the width. Separatrix temperature and collisionality also have a significant impact on the heat flux width in the drift dominant regime. By fixing the safety factor , the separatrix temperature , the critical diffusivity is \chi$_{c}$ \propto A$^{\(1/2}$/(Z(Z+1)$^{\(1/2}$Bp$^{2}$).