AVS 45th International Symposium
    The Science of Micro-Electro-Mechanical Systems Topical Conference Monday Sessions
       Session MM+VT-MoA

Paper MM+VT-MoA7
The Knudsen Compressor as a Micro and Macroscale Vacuum Pump Without Moving Parts or Fluids

Monday, November 2, 1998, 4:00 pm, Room 324/325

Session: Vacuum MEMS and Microanalysis
Presenter: S.E. Vargo, University of Southern California
Authors: S.E. Vargo, University of Southern California
E.P. Muntz, University of Southern California
G.R. Shiflett, University of Southern California
W.C. Tang, Jet Propulsion Laboratory
Correspondent: Click to Email
Microelectromechanical systems (MEMS) are rapidly becoming integral components of space missions and are finding an increasing utilization in commercial applications. Several current lander, probe and rover missions under study at NASAs Jet Propulsion Laboratory (JPL) focus on utilizing MEMS based instruments for science data gathering. These small instruments and NASAs new commitment to faster, better, cheaper missions has brought about the need for novel approaches to satisfying mission requirements. For example, a miniaturized mass spectrometer is currently under development at JPL that is designed to provide in-situ gas composition analyses of planetary atmospheres. This device utilizes a micromachined quadrupole array to provide comparable performance to a commercial large-scale unit but with much less mass, power and volume. However, the miniaturized mass spectrometer system lacks a vacuum pump that can meet future mission requirements. One attractive candidate for a vacuum pump is the Knudsen Compressor that is under collaborative development at the University of Southern California (USC) and JPL. The Knudsen Compressor is a vacuum pump that operates on the rarefied gas dynamic phenomenon of thermal transpiration, which is the development of a pressure difference between two volumes of gas via a temperature difference between the ends of small channels joining the volumes. A laboratory-scale Knudsen Compressor has previously been tested at USC@footnote 1@ with its success leading to the design and fabrication of a micromechanical version. This device has two overwhelmingly attractive features over miniaturized or mesoscale vacuum pumps - no moving parts and no fluids. The Knudsen Compressor is applicable in MEMS instruments as well as to larger, more standard pumping applications.@footnote 2@ The paper will include calculations of pumping speed, power usage, size and ultimate pressure for several applications of the Knudsen Compressor. @FootnoteText@ @footnote 1@Vargo, S.E. and Muntz, E.P. (1997): An Evaluation of a Multiple-Stage Micromechanical Knudsen Compressor and Vacuum Pump. In: Rarefied Gas Dynamics, Proceedings of the 20th International Symposium on Rarefied Gas Dynamics, Peking University Press, p995-1000, Beijing. @footnote 2@Pham-Van-Diep, G., Keeley, P., Muntz, E.P., Weaver, D.P. (1995): A Micromechanical Knudsen Compressor. In: J. Harvey and G. Lord Ed. Rarefied Gas Dynamics, Oxford University Press, 715-721.