Thermal interaction of plasma with Gas Puffing

This paper presents a model of gas injection treating coherently matter deposition and thermal effects on the plasma. It is demonstrated from an analytical model that an injection can trigger thermal bifurcations toward radiative or recombinant regimes. 1D simulations were performed to study the radial dynamics. They indicate that the injection can create a cold detached region in the outer plasma. The ionization front is located at the transition between this zone and the hot plasma, characterized by a radiative layer and strong temperature gradients. In spite of a better neutral penetration, strong sources are needed for efficient core fuelling and extrapolations for ITER remain pessimistic. Moreover a thermal instability linked to the bifurcation is evidenced for strong particle sources. However, a 1D parallel model shows that the perturbation linked to the injection can remain localized along the parallel direction, thus favoring neutrals penetration, but this effect strongly depends on the perpendicular–parallel transport interplay.