Eric M. Guild

Date of Award


Document Type


Degree Name

Master of Science


Department of Engineering Physics

First Advisor

Glen P. Perram, PhD.


This work examines the diffusion of rubidium through a small diameter tube alone and in the presence of noble gases. A fluid dynamics analysis is investigated to aid in choosing a method for transferring atomic rubidium vapor that is reliable and efficient. Solutions to the time dependant ordinary differential equation describing the experimental flow properties of the system reveal more precise outcomes than previously practiced routines. Resolved viscosities and Poiseuille flow theory velocity profile distributions are characterized for noble gas carriers of the rubidium vapor. Applying Reynolds Numbers to the flow experiments provides pressure differential boundaries that are employed in the successful rubidium vapor transfer process. Atomic spectroscopy is demonstrated through the use of a rubidium D1 resonate diode laser to record an absorption spectrum and extract alkali vapor densities that successfully propagated through a 12 cm long capillary tube with a 500 μm inner diameter. Rubidium number densities on the order of 1.384 x 1012 cm-3, 4.615 x 1011 cm-3 and 9.890 x 109 cm-3 were recorded for interaction path lengths of 0.05 cm, 0.15 cm and 7.0 cm, respectively. Number densities were achieved through the constant flow and diffusion of a helium/rubidium combination. Sustaining a constant pressure differential between 80 and 150 Torr across the capillary tube assisted in transferring the rubidium vapor through a small inner-diameter hollow-core tube.

AFIT Designator


DTIC Accession Number


Included in

Optics Commons