First Advisor

Erik Sánchez

Date of Award

2014

Document Type

Thesis

Degree Name

Bachelor of Arts (B.A.) in Physics and University Honors

Department

Physics

Subjects

Microscopes -- Design, Microscopy -- Research, Rarefied gas dynamics

DOI

10.15760/honors.59

Abstract

A novel design for a high intensity micron-scale supersonic free-jet source is described. This design has been implemented in a scanning helium neutral atom microscope at Portland State University, but has not been otherwise investigated. It is proposed that removing the skimmer component of a free-jet source can, under correct operating conditions, allow a comparable intensity beam to be created at greatly reduced complexity. The dsmcFOAM OpenFOAM solver was used to model rarefied gas dynamics of skimmed and un-skimmed helium atom sources. This modeling suggests that gas-gas scattering and shock structures occur in un-skimmed sources but can be compensated for with small aperture diameters and high source flow rates. If the comparable operation of skimmed and un-skimmed sources can be demonstrated it will greatly reduce the cost and complexity of helium atom sources for neutral atom microscopy and other applications.

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In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

Persistent Identifier

http://archives.pdx.edu/ds/psu/11972

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