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Low Speed Nano/Micro/Meso-Scale Rarefied Flows Driven by Temperature and Pressure Gradients

Summary: Low Speed Nano/Micro/Meso-Scale Rarefied Flows Driven
by Temperature and Pressure Gradients
E.P. Muntz,
A.A. Alexeenko*, S.F. Gimelshein*, A.D. Ketsdever**, Y.-L. Han*,
M.P.Young**, J.H. Park*, C. Ngalande* , N.P. Selden*, R.H.Lee*
* University of Southern California, Department of Aerospace and Mechanical Engineering
Los Angeles, CA 90089-1191
** United States Air Force Research Laboratory, United States Air Force Research Laboratory
Edwards Air Force Base, CA 93524, USA
Abstract. Gas flows in nano/micro-scale channels are of considerable practical as well as scientific interest. The present
discussion is guided by experience gained during investigations at USC of three technologies; all involving the use of gas
flows in both relatively long and short channels with characteristic cross-sectional dimensions from millimeters to
nanometers. One technology is a meso-scale, continuous trace-gas pre-concentrator, for portable detection of fractional
trace-gas concentrations down to 1E-12. Flow channels in the pre-concentrator, which range in characteristic lateral
dimensions from several tens of micrometers to below one nanometer, can be driven by either relatively modest pressure
and/or temperature differences. Another technology is a micro/meso-scale solid state compressor or vacuum pump, now
relatively well known as the Knudsen Compressor. It has no moving parts and is driven by thermal creep flow, which in
one version is generated by applying longitudinal temperature gradients along the walls of the flow channels. The
channels have cross-sectional dimensions varying from hundreds of micrometers to tens of nanometers. Both of these
technologies generally operate at around atmospheric pressure or below, resulting in flow conditions that are


Source: Alexeenko, Alina - School of Aeronautics and Astronautics, Purdue University


Collections: Engineering