Dielectric surface discharges: effects of combined low-energy and high-energy incident electrons

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Dielectric surface discharges: effects of combined low-energy and high-energy incident electrons

Balmain, K.G. / Hirt, W.

In simulation of the exposure of spacecraft insulating materials to the energetic-electron environment of synchronous orbit, a study has been made of the effect on dielectric surface discharges of adding high energy electrons at 5 pA/cm² to a primary 20 keV, 10 nA/cm² electron beam, the high-energy broad spectrum particles having been produced by the beta-decay of Strontium-90. Kapton exhibits the most surprising effects, which are significantly increased discharge strength, increased waiting time between discharges, and a decreased number of discharges per specimen before discharge cessation. Mylar exhibits similar but less pronounced effects, while Teflon is relatively unaffected. There is evidence that with Kapton and Mylar the high energy electrons act in some way to delay the instant of discharge ignition so that more charge can be accumulated during charge-up and hence released during arc discharge.