A novel method of levitation, using an actively controlled electric field, launches, captures, and stably suspends a microscopic (∼15 μm) particle in high vacuum. While held to within one diameter in the vertical direction, the particle is allowed to oscillate nearly freely in the horizontal plane under the influence of a central restoring force. The damping of horizontal oscillations was measured over the pressure range from 10−2 to 10−8 Torr. The damping was observed to be proportional to pressure down to less than 10−6 Torr, where residual (pressure independent) damping became significant. An absolute high vacuum gauge based on the pressure-dependent damping observed with this apparatus could operate linearly throughout at least a six decade range. A prototype gauge design is suggested.
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Hinkle et al. (1990) studied this question.