Abstract
A shock-heated molecular beam source which can generate high energy beams in a range of 1-several eV is presented. Non-diaphragm type design of the shock tube enables our beam source to repeatedly generate pulsed beams. Since the rapid evacuation of residual gases requires the reduction of the tube volume, the tube diameter is only a few millimeters. Moreover, the shock formation distance is made as short as possible by a current-loop valve which opens completely within 200 gs. The prototype beam source demonstrated repetitive beam generation with the translational energy controlled by the initial pressure ratio although the energy was limited to below 1 eV. In order to improve the performance of the beam source, we investigated shock propagation in convergent tubes whose diameter is comparable to the thickness of boundary layer. The results suggest that the optimized geometry with an improved evacuation system enables generating molecular beams with the energy of more than 1 eV at the frequency of 0.5 Hz.
