A highhyphen;intensity supersonic nozzle beam source is described, whose beam energy can be varied between 2 and 170 meV (helium). Experimental performance and timehyphen;ofhyphen;flight measurements on cold helium beams are reported. Condensation in the free jet expansions of helium has been studied by mass spectrometric detection of He+2. A correlation between the maximum speed ratio and the onset of clustering is observed.
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