1714 Performance Evaluation of High-Energy Molecular Beam Source with an Ultra Small Shock Tube

In order to generate high-energy molecular beam in a range of 1 - 5 eV without any undesirable impurities, we are developing a beam source with a non-diaphragm type shock tube which can operate at a repetition rate high enough for efficient data acquisition. The volume of our shock tube is much smaller than that of conventional ones so that the evacuation time between each shot can be made as short as possible. We investigated the influence of tube diameter on shock Mach numbers using one-dimensional numerical simulations. In addition, we measured shock Mach numbers in convergent tubes of which diameters linearly decrease from 4 mm to 2 mm, and estimated the translational energy of shock-heated beam. The results suggest that a convergent shock tube with the optimized geometry could generate higher energy beam than straight one.