Modified single point-to-plane corona poling rotating system for production of electret dosimeters

A "modified single point-to-plane corona poling rotating system" was designed, constructed and well studied for electret production of radiation dosimeters. This innovative system which was patented is based on a new corona charging method which exposes the corona beam towards the surface of a material such as Teflon polytetrafluoroethylene (PTFE). The corona beam from a metal needle automatically scans a defined diameter of the surface of a Teflon PTFE disc placed concentric on a heated rotational metal disc electrode for a certain period of time. Some parameters affecting the uniformity and stability of the deposited charges on the Teflon disc surface include; (a) needle-to-Teflon disc distance, (b) single point-to-plane system modes; modified versus classical, (c) Teflon disc charge polarity, (d) Teflon disc diameter and (e) electret formation process. Large-area (14 cm diameter) Teflon disc electrets (0.2 mm thick) with steady-state negative or positive uniform electrostatic charge potentials up to 1.2 kV with stability up to 77 days studied were produced. The Teflon electret discs produced have high quality with acceptable parameters to be applied for different applications in particular as electret radiation dosimeters. In this paper, the results of parametric studies of the modified corona rotating system are presented, discussed and compared with those of some common corona electret production methods.