RADIATION-INDUCED ELECTRICAL DISCHARGES IN COMPLEX STRUCTURES

Polyethylene terephthalate (PET) foils were exposed to 25 keV electron beams of 3 nA/cm2 which has been known to charge the PET surface to -15 kV or more and to produce rapid pulsed discharges sufficient to lower the magnitude of the surface potential significantly. The major experimental finding is that the pulse discharges often propagate to nearby mutually biased electrodes and can create a full vacuum breakdown between stainless steel electrodes, rarely if biased at as little as 100 V, but often if biased at 300 V. The phenomena appear to be associated with the pulsed creation of dense plasma from the discharging dielectric, and the pulsed volume of gas evolved is equivalent to roughly 0.1 to 0.4 mm3 at 1 atmosphere for nominally 50 cm2 samples. The plasma could evolve to interconnect more than 2 electrodes. Additionally, PET pulse rates were strongly dependent upon the proximity of sharp edges, either metallic or dielectric.