Multi-physics modeling of a spark plasma jet igniter

The plasma-fluid multi-physics process of a spark plasma jet igniter is studiednumerically. The plasma discharge, gas heating, mass, and heat transfer processes in one working cycle are modeled and analyzed. Gas discharge starts inside the igniter, the 'ladder-like' dielectric wall structure promotes the transition of a volumetric discharge to a surface discharge, establishing a conductive path between the electrodes over a timescale of tens of nanoseconds. Once the electrodes are short-circuited, a new spark-arc discharge channel forms, heating the gas up to 7000-10 000 K in the discharge channel and 2000-4000 K in the igniter. The gas molecules are dissociated and pushed out of the igniter, forming a 'heating core' with high temperature (2000-3000 K) and chemical activity following a wavefront propagating with a velocity of 750-875 m s-1. The calculated evolution of the heating core agrees well with the ICCD measurements. It is found that the 'ladder-like' structure does not affect the penetration depth or expansion radius of the heating core, but leads to a complex vortical flow that allows for chemical activity species to be brought out into the ambient gas.