Evidence for Discrete Plasma Emission during Dielectric Discharge Events

This paper describes laboratory measurements of the plasma blowoff associated with electrostatic discharge events. Samples of Teflon and OSR were irradiated with a spectral energy electron source (1 to 100 keV) and the charge blowoff during spontaneous discharge events was examined using gridded, biased Faraday cups. For typical discharges an initial discrete burst of fast electrons (≃ 5-10 kV) is seen followed by a slow-moving (vD ≃ 5 × 106 cm/s) charge neutral plasma. The average plasma density near the dielectric sample (ΔZ≃ 7 cm) was measured to be ne ≃ 4 × 1010 cm-3 for the Teflon samples. Evidence oe neutral particle evolution was also qualitatively measured. These data support the model of dielectric discharges as being discrete, nonuniform events and could impact models which assume uniform or homogeneous discharging of charged dielectrics.