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Updated: Jun 7, 2026

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
Measuring the density of a molecular cluster injector via visible emission from an electron beam
D P Lundberg1, R Kaita, R Majeski
1Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543, USA. dlundberg@pppl.gov
Abstract:
A method to measure the density distribution of a dense hydrogen gas jet is presented. A Mach 5.5 nozzle is cooled to 80 K to form a flow capable of molecular cluster formation. A 250 V, 10 mA electron beam collides with the jet and produces H(α) emission that is viewed by a fast camera. The high density of the jet, several 10(16) cm(-3), results in substantial electron depletion, which attenuates the H(α) emission. The attenuated emission measurement, combined with a simplified electron-molecule collision model, allows us to determine the molecular density profile via a simple iterative calculation.
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