High speed pellet injection with a two-stage pneumatic gun

The injection of pellets of frozen hydrogen isotopes into fusion plasmas is envisioned as a fueling technique for future fusion reactors. Research is underway to obtain high injection speeds for solid H2 and D2 pellets. The optimization of a two-stage light gas gun is being pursued by the Milano group; the search for a convenient method of creating pellets with good mechanical properties and a secure attachment to the cold surface on which they are formed is carried out in Frascati. Velocities >2000 m/s have been obtained, but reproducibility is not yet satisfactory.