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arXiv · 1609.09020

Characterizing gas flow from aerosol particle injectors

Daniel Horke·Nils Roth·Lena Worbs·Jochen Küpper
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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 $4\times10^{16}$~cm$^{-3}$ 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.

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Daniel Horke, Nils Roth, Lena Worbs, Jochen Küpper. 2016-09-28. Characterizing gas flow from aerosol particle injectors. https://doi.org/10.1063/1.4978914

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