A nanonewton force facility and a novel method for measurements of the air and vacuum permittivity at zero frequencies

摘要

A nanonewton force facility, based on a disk-pendulum with electrostatic stiffness reduction and electrostatic force compensation, for the measurement of horizontal forces in the range below 1 (mu)N, is presented. It consists of a measuring system and an identical reference system. Recent experiments with the nanonewton force facility have achieved agreement between an electrostatic force and a gravitational force of 80 nN with an uncertainty of less than 3percent. A novel method for measurements of the air (vacuum) permittivity at zero frequencies by means of the nanonewton force facility is presented. First measurements in air show a permittivity of the air epsilon approx= 8.71 X 10~(-12) F m~(-1) with an uncertainty of 3percent. From a theoretical analysis, it follows that this method can be used for the measurement of the vacuum permittivity (epsilon)_(0) at zero frequencies with a relative uncertainty of about 10~(-5). The precise measurement of the vacuum permittivity (epsilon)_(0) for an electrostatic field would be another test for the correctness of Maxwell's equations.