Development of a Fast Valve Assisted Mechanical Launcher for Cryogenic Pellets

Plasma fueling and disruption mitigation (DM) are two of the many key aspects in the successful operation of high-temperature fusion devices. Pellets of different gases like hydrogen, its isotopes, neon, and argon solid-ified at cryogenic temperature are used for fuelling and DM studies. A gas gun-based pellet injector has been developed for the large-size pellet formation and shattering study. Instead of the conventional fast valve injection mechanism, a new technique called mechanical pellet launching system (MPL) has been developed and tested for pellet launching. The MPL is a fast valve-driven pneumatic punch. The advantage of using it over the con-ventional technique is, the required impulse to dislodge the pellet can be achieved at lower propellant pressure. Before applying to the cryogenic pellets, the MPL has been tested up to 4 MPa pressure on a test bench, and a punch speed of 2-12 m/s has been achieved for 0.2 -4 MPa pressure. The developed MPL has been success-fully applied on 6.2 mm lp x 4.2 mm dp cylindrical hydrogen pellets. Details of the pellet formation device, MPL system, and experimental results are presented in this paper. & COPY;2023 The Japan Society of Plasma Science and Nuclear Fusion Research