Supersonic Flow Patterns from Electrothermal Plasma Source for Simulated Ablation and Aerosol Expansion Following a Fusion Disruption

Abstract

A pulsed electrothermal plasma source of a capillary discharge operating in the confined controlled arc regime is investigated to simulate the source term for ablation-induced regime of fusion reactor following hard disruption, in which ablation of diverter surface produces large aerosol transporting into the vacuum vessel. The source is attached to a converging–diverging micro-nozzle transition region to allow for the plasma flow and expansion into a large volume simulating large chamber of fusion reactor aerosol expansion to facilitate modeling of the plasma transport. This transition region connects to a 4 mm diameter capillary source and has a 3.33 mm converging section with a 2° converging angle, followed by a 146.7 mm diverging section with a 60° diverging angle, thus making an overall transition length of ~150 mm. The diverging section has an exit diameter of 50.82 cm to open into a large volume of the same exit diameter and a length of 1 m. Preliminary computation results indicate about 21 Mach number at the diverging exit and drops down to 0.7 Mach number after suffering from multiple shocks in the large uniform expansion volume. The plasma parameters entering the large chamber are maintained constant along the axis of the chamber for a simulated 1-D condition.