Articles you may be interested inElectron beam generation in a diode with different ferroelectric cathodes Electron beam generation using a ferroelectric cathode AIP Conf. Proc. 472, 918 (1999); 10.1063/1.58887High brightness electron beam produced by a ferroelectric cathode

We report extensive experimental data on electron emission from lead-zirconate-titanate ferroelectric ceramics. A 1-2 MV/m pulse is applied to a gridded ferroelectric cathode and diode currents of up to 120 A/cm 2 are measured across an A-K gap of 5ϫ10 Ϫ2 m, with the anode at 35 kV. Both the current and the anode voltage pulse duration may extend to several microseconds. The measurements extend previously reported data by nearly two orders of magnitude in the diode voltage and by a factor of more than 3 in the diode spacing. Two major regimes of operation were identified. In the first ϳ1 s the ferroelectric cathode controls the electron flow through the diode. Beyond this time plasma effects dominate the current flow. The results are of importance to the development of novel cathodes for high current electron beam generation.

It has been shown experimentally that electron current densities of more than 30 A/cm' can be achieved from a cathode made of ferroelectric ceramic, when applying a field of order 0.1 MV/m. This current exceeds the Child-Langmuir current by two orders of magnitude. The current in the diode varies linearly with the applied voltage, provided that the latter is positive. In this theoretical study we show that the ferroelectric material plays a crucial role in the emission process. When a voltage is applied to the ferroelectric, the internal polarization field varies and the amount of screening charge required decreases. As a result, the electrons distribution near the cathode changes, forming a cloud which fills part of the diode gap. If now a positive voltage is applied to the anode, electrons are readily transferred through the diode gap. The qualitative and quantitative results of the theory are in good accordance with the experiment.

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