DIAGNOSTICS OF GAS CLUSTER FLOWS BY TRANSVERSE INTENSITY PROFILE OF MOLECULAR BEAM

An experimental method for diagnostics of clusters in molecular beams formed from supersonic gas jets is described. The method is based on measuring the cross-section profile of the mass intensity of the beam at a given distance behind the skimmer and it allows one to determine the main parameters: the mean cluster size, the ratio of clusters to monomers and the cluster flow density. The described method can be used to diagnose cluster beams of any pure gases, without creating special models or determining empirical constants. Since the cluster beam has a high intensity, highly sensitive and complex equipment is not required for measurements. With this method, the average sizes of Ar clusters in the range from 50 to 2,000 molecules per cluster were determined. The reliability of the obtained values of the mean cluster sizes is confirmed by a comparison of the results with the data of other authors obtained by the various experimental methods using the similarity parameter of flows with condensation (the Hagena parameter) Г*. The physical limitations of the described method were analyzed.

Keywords:
gas cluster, transverse cluster beam profile, speed ratio, mean cluster size.
УДК 544.277.6, 544.277.4, 533.6.011.8, 539.198

DIAGNOSTICS OF GAS CLUSTER FLOWS BY TRANSVERSE INTENSITY PROFILE OF MOLECULAR BEAM