Electrostatic Current Generator Having a Disk Electret as an Active Element

An electrostatic current generator having a disk electret as the active element is described. The electret consists of two oppositely polarized half-disks producing an electric field normal to the plane of the electret. The electret constitutes the rotor of the generator and is located between two pairs of conducting half-disks which constitute the stator of the generator. The field of the electret induces charges on each half-disk of the stator. The magnitude and polarity of these charges at any given time are determined by the angle formed at this particular time between the plane separating the two halves of the electret and the plane separating the half-disks of the stator. When the half-disks of the stator are appropriately connected through an external circuit, an ac current is produced. The order of magnitude of the peak value of the current is given by I ≈
_e
ωS where ae is the effective surface charge density of the electret, S is the total area of the flat surfaces of the electret, and w is the angular velocity of rotation of the electret.