Velocity Distribution in a Short-Pulsed Nozzle Beam Measured by Means of Time-of-Flight Metastable Spectroscopy

抄録

A time-resolved study of nonsteady characteristics in a pulsed nozzle beam whose width is less than 50 μs was carried out. The velocity distributions in pulsed molecular beams were investigated by means of “TOF-metastable spectroscopy” with a high time-resolution, e.g., 0.5 μs. The variations of the relative intensity and speed ratio within the pulse duration were determined. Both of the measured quantities reached maxima near the center of the pulse where the narrowest velocity distribution was obtained. At this position a typical speed ratios were 28 for He, 36 for Ne, and 38 for Ar, and corresponding stream temperatures were 1.2 K, 0.8 K, and 0.8 K, respectively. These values were almost the same as those obtained by a continuous nozzle source with an equivalent nozzle design.