New results on electron emission from PZT ferroelectric cathodes

Ferroelectric cathodes may offer a source of high current density electron beams for applications where the use of conventional cathodes is limited by the required current density, cathode poisoning, or lifetime. In a ferroelectric cathode, electrons are emitted when the spontaneous polarization is rapidly changed by a pulsed electric field applied across the ferroelectric. When no additional voltage is applied to a planar diode gap, emission current densities are on the order of ~1 A/cm². When an additional field is applied to the gap, we have measured current densities of up to 100 A/cm². In this paper we report on two topics: (1) beam extraction into a drift tube at low (10-20 kV) voltage and, (2) electron emission, transverse to an applied magnetic field, from a cylindrical ferroelectric cathode