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Phoretic and Radiometric Force Measurements on Microparticles in Microgravity ConditionsThermophoretic, diffusiophoretic and radiometric forces on microparticles are being measured over a wide range of gas phase and particle conditions using electrodynamic levitation of single particles to simulate microgravity conditions. The thermophoretic force, which arises when a particle exists in a gas having a temperature gradient, is measured by levitating an electrically charged particle between heated and cooled plates mounted in a vacuum chamber. The diffusiophoretic force arising from a concentration gradient in the gas phase is measured in a similar manner except that the heat exchangers are coated with liquids to establish a vapor concentration gradient. These phoretic forces and the radiation pressure force acting on a particle are measured directly in terms of the change in the dc field required to levitate the particle with and without the force applied. The apparatus developed for the research and the experimental techniques are discussed, and results obtained by thermophoresis experiments are presented. The determination of the momentum and energy accommodation coefficients associated with molecular collisions between gases molecules and particles and the measurement of the interaction between electromagnetic radiation and small particles are of particular interest.
Document ID
19970000464
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Davis, E. James
(Washington Univ. Seattle, WA United States)
Date Acquired
August 17, 2013
Publication Date
September 1, 1996
Publication Information
Publication: Third Microgravity Fluid Physics Conference
Subject Category
Materials Processing
Accession Number
97N10431
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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