D/sub 2/ - pellet injection system

For density build-up of a target plasma for neutral injection in the stellarator ''Wendelstein W VIIA''and for refuelling of the divertor tokamak ASSDEX, pellet light gas guns have been developed. In a continuous flow cryostat cooled by liquid helium with a comsumption of 2 - 3 liter liquid helium per hour deuterium was condensed and solidified. To prevent the propeller gas entering the torus was used. In one system a 3.6 mm guiding tube following the barrel was applied successfully. By optical diagnostics pellet velocity, pellet size and pellet trajectory is measured. For a pellet centrifuge system investigations of carbon fiber rotors were made up to surface velocities of 1500 m/s