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 di ff erent 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 conventional 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 successfully applied on 6.2 mm l p × 4.2 mm d p cylindrical hydrogen pellets. Details of the pellet formation device, MPL system, and experimental results are presented in this paper.