Transport process of high-speed impurity pellets through curved guide tubes

Curved guide tubes to transport high-speed pellets are used for pellet inje ction into plasma devices. This article describes the transport process of the high-speed pellets through curved guide tubes. The pellets pass through the curved tubes with repeating reflections. Using the equation of frictio n at each reflection point, the velocity and the direction of the output pe llet are calculated by following the pellet trajectory. The analytic expres sions, with respect to the velocity and the direction of the output pellet, are also derived. It has been confirmed that there is good correspondence between the results obtained by following the pellet trajectories, those by the analytic expressions and those by the experiments. The analytic expres sions are particularly useful for the design and making of the curved guide tubes used in the pellet injection. (C) 2000 American Institute of Physics . [S0034-6748(00)02910-5].