Altering the electrical conductivity of dielectrics

When a spacecraft is orbiting the earth in a geo-synchronous orbit it is bombarded by a variety of charged particles trapped by the earth's magnetic field. The most troublesome type of radiation is electrons which cause charging of the dielectrics which are used as thermal control surfaces on the outside of the spacecraft. When a dielectric is charged beyond the discharge threshold of the material arcing occurs producing spurious switching of the electronic units aboard the spacecraft. A solution to the problem would be to invent new materials combining good thermal insulation properties and sufficiently high electrical conductivity. Composite materials having these properties have already been designed and tested in various configurations [1]. Another method of producing a material with the required properties is to select a dielectric and alter its bulk electrical conductivity by irradiation with charged particles [2]. This paper describes the principle involved in this method and tests carried out in order to verify it. Electrons of sufficient energy to penetrate a dielectric sheet were used and high flux irradiation of Kapton showed enhancement of its electrical conductivity which remained after the irradiation was stopped.