Optical investigation of fast pulsed discharge on surface of ceramics for environmental applications
Pulsed surface discharge on the surface of ceramics was investigated experimentally. Photon counting method was applied to clarify preceding phase of the discharges. The results indicated the effect of charge injection from electrodes. Pulsed surface discharge reactor for decomposition of nitrogen oxides utilizing honeycomb ceramics was proposed. Framing and streak observation was carried out with image converter cameras. Emission spectra from the discharge were investigated with spectrometer. Uniform surface discharges on honeycomb ceramics were successfully obtained utilizing pulsed power generator with a SI-thyristor.
Light Emission before and during Prebreakdown on Polytetrafluoroethylene Surface with Metallized Electrodes under AC Voltage Application in Vacuum
Light emission before and during electrical breakdown from the surface of polytetrafluoroethylene (PTFE) with metallized electrodes has been investigated with ac electric field application along the polymer surface, using a photon counting method, in order to understand the initiation mechanism of the prebreakdown. Two distinct stages of light emission were observed depending on the applied voltage: a low-level stable light emission, electroluminescence (EL), before prebreakdown and an irregular intense light emission during prebreakdown. Before prebreakdown, charge injection from the electrode directly into the polymer surface layer results in EL emission and the formation of long-term electron space charges away from the electrode. The crucial factor of prebreakdown initiation is the strong modification of the local electric field near the electrode because of space charge formation in the surface layer before prebreakdown. The prebreakdown with intense light emission is initiated by detrapping the long-term trapped electrons toward the electrode via the vacuum and/or the surface layer in the positive half-cycle of ac voltage.
Anomalous Annealing Behavior of Arsenic Implanted Silicon as a Function of Dose and Energy
Anomalous annealing behavior of damage in As implanted Si has been investigated by channeling effect measurements. Room temperature As implants with doses from 1014 to 2 × 1016cm-2 at energies ranging from 50 to 250 keV into Si were annealed over the range of 600°C to 1100°C. Anneal temperatures ≥ 950°C reduce the disorder for ion doses of 0.5 to 1 × 1016 cm-2 at energies between 50 and 250 keV. Anomalously high residual disorder was found for the intermediate doses of 2 × 1014 to 2 × 10/cm2 implanted above 100 keV. For this intermediate dose, annealing of implants performed at liquid nitrogen temperatures did not show significant reduction in this damage. However implants at 200° to 300°C indicate a lower amount of damage compared to the room temperature implants.