Electron-beam-induced discharge phenomena of teflon films for space use

Abstract

We investigated the discharge phenomena of Teflon FEP (fluorinated ethylene propylene) films used as thermal control material of spacecraft by electron-beam irradiation simulating hot plasma in space. FEP films of two thicknesses, 25 and 127 μm, were tested. The results obtained were as follows. (1) In 127-μm-thick FEP film, a surface discharge triggered by high electric field at the triple junction of the edge of the metal frame occurred. (2) In 25-μm-thick FEP film, punchthrough discharge accompanied by surface flashover occurred. (3) Discharge frequency increased as nearly the 1/2 power of the electron-beam current density under constant irradiation energy. On the other hand, it increased linearly with the irradiation energy under constant beam current density, but with sufficient threshold electron energy to cause discharge. These results were explained by comparison between the surface electric field and the bulk electric field in FEP film obtained analytically by using a two-dimensional charging model. © 1999 Scripta Technica, Electr Eng Jpn, 129(1): 10–19, 1999