Characterizing gas flow from aerosol particle injectors
Abstract
A novel methodology for measuring gas flow from small orifices or nozzles into vacuum is presented. It utilizes a high-intensity femtosecond laser pulse to create a plasma within the gas plume produced by the nozzle, which is imaged by a microscope. Calibration of the imaging system allows for the extraction of absolute number densities. We show detection down to helium densities of ~cm with a spatial resolution of a few micrometer. The technique is used to characterize the gas flow from a convergent-nozzle aerosol injector [Struct.\ Dyn.~2, 041717 (2015)] as used in single-particle diffractive imaging experiments at free-electron laser sources. Based on the measured gas-density profile we estimate the scattering background signal under typical operating conditions of single-particle imaging experiments and estimate that fewer than 50 photons per shot can be expected on the detector.
Cite
@article{arxiv.1609.09020,
title = {Characterizing gas flow from aerosol particle injectors},
author = {Daniel Horke and Nils Roth and Lena Worbs and Jochen Küpper},
journal= {arXiv preprint arXiv:1609.09020},
year = {2017}
}