Gas Injection and Ionization in the Century High-Power Repetitive Z-Pinch System

Zap Energy is developing the shear-flow stabilized Z-pinch concept as a commercially viable path to fusion energy. This is a pulsed approach to fusion that requires precisely controlled gas injection conditions and timing to reliably ionize and pinch the fuel gas. Few gas injection valves meet the unique combination of injection parameters required by Zap's fusion research devices (FuZE and FuZE-Q) such as gas pressure, density, valve cycle time, response time, and vacuum compatibility. Durability and reproducibility are also factors in high repetition rate operations on the Century platform. [1] Century is a technology demonstration platform at Zap Energy designed for integrating high-average-power repetitive pulsed power, high duty-cycle cathodes, and liquid metal wall systems as an intermediary step between Zap's laboratory and plant-scale fusion energy technology. Century uses Parker Series 9 valves which have been put through a series of tests to determine how they perform under different operating conditions, and their unique failure modes, as part of Zap's larger gas injection program. Operational experience with long duration, high repetition rate gas injection at up to 0.2 Hz is described. The impact of gas injection parameters on ionization and plasma formation is discussed.