In the current prototype fourteen pistons are mounted on the steel sphere with inner radius of 0.5m (staggered rings of seven pistons above and below the equator). Interior of the sphere is filled with tangentially pumped molten lead (Pb) such that evacuated cavity (vortex) is formed in the middle of the sphere.
A scaled prototype of the magnetized target fusion compression system has been designed and built in General Fusion Inc. to test full size pistons and algorithms of their synchronization.Due to the close acoustic match between steel and lead most of the pressure wave is transmitted into the liquid lead. Discrete pressure waves produced by the individual pistons merge into a converging pressure wave as they propagate towards the evacuated cavity. When a combined converging wave hits the lead-plasma interface it is almost entirely reflected because of the severe mismatch between the acoustic impedances. This interaction results in a rapid inward acceleration of the interface.
Propagation of Pressure Waves in Compression System Prototype for Magnetized Target Fusion Reactor in General Fusion Inc.
Suponitsky, V., Plant, D., Avital, E., and Munjiza, A., 2012. Proceedings of the 30th International Symposium on Shock Waves. July 19-24, Tel Aviv, Israel.