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UI ME 1997-1998 Senior Capstone Design 
Team Zero-G
Electrostatic Levitator
 
 
 
Project Abstract
 
         The electrostatic levitator senior design project objective is to develop an apparatus for continuing research of fluid viscosity in microgravity.  The measurement of transport properties, specifically viscosity, near the critical point of a fluid is required to test our understanding of the unified theory of second order phase transitions.  Viscosity can be calculated by spinning the levitated sphere in a fluid of interest and measuring the rate of decay of the angular velocity as it spins down.  Levitation isolates the sphere from external forces which would interfere with the precise measurement of viscosity. 
         Team Zero-G is developing a levitator which utilizes high voltages applied to two electrodes to generate an electrostatic field that imparts a force on a charged sphere in the electric field.  The sphere is capacitively charged at launching; a negative charge is induced on the sphere’s surface by the attraction of electrons to the positively charged top electrode.  The current electrode configuration is designed to operate in one earth gravity, with a passive centering force in the radial direction.  As described by Earnshaw’s Theorem, an electrostatic field cannot create a three dimensional potential well, therefore, this apparatus requires an active control system that varies the potential difference between the electrodes to attain stable levitation.