Static Cling: A Mechanical Side-Effect of Dielectric Charging

Abstract

Space charging of dielectrics results in the build-up of electric fields between the trapped charge (typically electrons) and image charges in nearby conductors. Engineering assessments are typically concerned with the magnitude of the electric field relative to a discharge threshold. The same electric field, however, also results in strong electrostatic attraction. For rigid dielectrics (such as solar cell coverglasses, second surface mirrors, or printed circuit boards), the electrostatic forces have no consequences. But for lightweight flexible dielectrics, the electrostatic forces can lead to static cling. A simple 1-D analysis of the electrostatic force between trapped and image charges is presented, and the phenomenon is demonstrated by ground test video. The electrostatic force is sufficient to overcome the Earth’s gravitational force. The video shows significant movement in a single-layer thermal blanket of a periodic nature. As the material reaches a sufficient charge level, the electrostatic forces begin to dominate and the material starts moving until it makes contact with the ground plane, discharges, and the cycle begins again. Without the vacuum-deposited aluminum (VDA) layer on the Kapton film, the static cling would be permanent.