Development of High-Energy Molecular Beam Source Using Small Shock Tube

Abstract

We developed the molecular beam source with a non-diaphragm type small shock tube in order to generate high energy molecular beam and dissociated atomic beam. The measurement of the shock Mach number shows that the convergent type tube, the diameter of which linearly decreases from 4 to 2 mm, successfully increases shock Mach number compared to the straight tube although viscous dissipation increases in the convergent tube. We evaluated the characteristics of shock-heated beams by the time-of-flight technique. The shock tube with the optimized geometry can generate the molecular beam with the translational energy of more than 1 eV at the repetition rate of 0.5 Hz. The translational energy of the beam is reproducibly controlled by the initial pressure ratio. Furthermore, dissociated atomic beam is obtained for oxygen with the fraction of dissociation determined by the initial pressure ratio. These results demonstrate that the molecular beam source using the small convergent shock tube is a useful method to generate high energy and reactive atomic beams.