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

摘要

We present an all-optical method for measuring the average size, density, and mass fraction of large (＞50nm) clusters produced in cryogenically cooled, continuous gas jets. The technique combines three optical diagnostics-forward/backward Mie scattering detection, 90° 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.