EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Laboratory for Particle Physics Divisional Report CERN LHC/97-10 (DLO) Displacement and Emission Currents from PLZT 8/65/35 and 4/95/5 Excited by a Negative Voltage Pulse at the Rear Electrode

It is shown that non-prepoled PLZT ceramics, both in ferroelectric and antiferroelectric phase, emit intense current bursts when a negative exciting voltage is applied to the rear surface of the cathode. The spontaneous polarization induced in the bulk by applying the field through the cathode disk, creates a sheet of negative charge on the diode boundary of the ferroelectric. This, in turn, induces such a high electric field at the diode dielectric surface that electrons are ejected out from the ceramic surface into the vacuum. The coherent behaviour of the displacement and emitted current shows clearly that the emission is due to a variation of spontaneous polarization. A second effect generated by the application of the high voltage pulse at the rear side is the formation of a surface plasma. Applying a positive voltage to the anode, electrons are readily transferred through the diode gap. * University, INFN and INFM, Milan, Italy ** University of Silesia, Katowice, Poland *** CERN, LHC Division Nuclear Instruments and Methods in Physics Research A Administrative Secretariat Geneva, Switzerland LHC Division 25 November 1997 CERN CH 1211 Geneva 23 G. Benedek*, I. Boscolo*, J. Handerek**, S. Marchesini*, C. De Martinis*, H.Riege*** and A. Scurati*