The injection of pellets of frozen deuterium into magnetically confined, hot plasmas is one of the most attractive methods for refueling fusion power reactors. High injection speeds for solid deuterium pellets are necessary for improving the experimental analysis of pellet ablation in a hot plasma and the effects of the pellet on the plasma properties, in particular the confinement parameters. The optimization of a two‐stage light gas gun is being pursued; the search for the cryogenic conditions of freezing deuterium with good mechanical properties is carried out. In particular, the impurities concentration in deuterium during the condensation process has been studied. These developments have allowed one to reach velocities up to 3400 m/s for integer bare deuterium pellets (3 or 4 mm in diameter, 1–3×1021particles) with a reliability of 80%.