All-optical characterization of cryogenically cooled argon clusters in continuous gas jets

Abstract

We present an all-optical method for measuring the average size, density, and mass fraction of large (>50 nm) clusters produced in cryogenically cooled, continuous gas jets. The technique combines three optical diagnostics-forward/backward Mie scattering detection, 90 degrees scattering imaging, and neutral gas interferometry. Our measurement shows that cryogenic cooling and high backing gas pressure greatly enhance both cluster size and clustering ratio in continuous gas flow. Such a cluster source can be used as a potential target for intense, high-repetition-rate (>kHz) laser pulses. (C) 2014 AIP Publishing LLC.