The effect of condensation on the parameters of pulsed supersonic streams

We report on the results of mass-spectrometric measurements conducted in the pulsed supersonic streams of argon, nitrogen, and helium. Evolution of the time parameters of a stream determined as functions of the retarding pressure P ₀ is compared to the pattern of variation of the mass peak intensities corresponding to monomers and clusters. The transition of a gas flow into the condensation regime is accompanied by changes in the flight time and the halfwidth of the monomer signal measured in the molecular beam formed from the supersonic stream. It is demonstrated that the monitoring of the time parameters of a pulsed stream allows different condensation stages to be distinguished.