Thickness Scaling for ARC Discharges on Electron-Beam-Charged Dielectrics

A study of arc discharges on various thicknesses of electron-beam-charged Mylar, FEP Teflon and Kapton shows that the peak substrate current and the energy dissipated in a load resistor both exhibit maxima at a particular thickness of the order of 50 ¿m, for one set of experiment parameters. The experiments also show that, as thickness increases, this particular thickness is the transition from near-constant to decreasing released charge, and, for Mylar, from decreasing to near-constant arc duration. This transition is interpreted as being caused primarily for thin specimens by punchthrough formation and possibly influenced by the transition from conduction-dominated to emission-dominated charging. Additional low-energy ion exposure is shown to weaken and sometimes eliminate the arc discharges without radically altering the thickness scaling. At low fluxes, the incident ions are focussed into a central spot.