Cubic electrodynamic levitation trap with transparent electrodes

An unconventional electrodynamic suspension system with transparent planar electrodes is described which stably levitates charged solid particles or liquid droplets without the need for feedback control. The system has been used with particles ranging from about 1 to 100 mu m diam, under vacuum and within stationary and flowing gases. Operation within low conductivity liquids is possible in principle. The suspension system consists of six transparent conducting electrodes arranged as faces of a hollow cube. Four of these electrodes are driven by a variable-frequency two-phase ac source operating in the low audio frequency range. Advantages of this type of trap for aerosol studies include relatively wide-angle optical access and a geometry naturally suited to the use of three-axis de crossfields far particle manipulation. Conditions for stable levitation are reviewed as well as methods determining the radius, mass, charge, and density of a spherical levitated object. (C) 1996 American Institute of Physics.