Plasma-assisted electron emission from (Pb,La)(Zr,Ti)O3 ceramic cathodes

Abstract

Strong pulsed electron emission has been observed from 12/65/35 lead lanthanum zirconate titanate ceramic composition in two different nonswitched phases at room temperature and at the temperature 100 °C. The electron emission parameters of this composition appear to be independent of phase for the two phases investigated. Fast photography and direct observation show that the strong electron emission occurs from the surface discharge plasma. The new experimental data make it possible to demonstrate the validity of the Child–Langmuir law for this electron emitter. A pulsed plasma lead lanthanum zirconate titanate ceramic cathode with burst frequency up to 100 kHz and collector current density up to 10 A/cm2 is developed.

Features and technology of ferroelectric electron emission

“…Similar observations are reported in Ref. [32] and the effects have been proposed for application in flatpanel displays [33]. During the whole expansion process the plasma forms a nearly homogeneous thin sheet confined to the bare FE surface and partially screens the negative surface charge, provided very strong switching and extraction fields are avoided.…”

Kiloampere and microsecond electron beams from ferroelectric cathodes

“…[1,14] have confirmed the presence of a plasma with a density of 10 10 -10 12 cm -3 on the ferroelectric cathode surface. Experiments have also confirmed the presence of high energy electrons, of order a few keV, being emitted from the cathode surface [7,14].…”

“…Once the plasma is created at small microplasma points [1] (also called triple points [9] where the vacuum, metal, and the dielectric meet), it can then propagate across the ferroelectric cathode surface at a finite velocity leading to an optimum point of time (and thus delay) when the plasma is well established across the surface (the plasma emitting area is maximal) and the maximum current can be extracted from the cathode surface. The exact manner in which this plasma would propagate would be dependent on the geometry of the diode as well as the ratio of the size of the cathode to the anode-cathode gap distance, as well as other 7 geometrical considerations such as a solid or annular beam.…”

“…Attempts have been made over the last few years to explain the process of electron emission from ferroelectrics [1,9,10,11,12]. The traditional explanation is that the emission results from a polarization switching effect which is initiated by a pulse across the ferroelectric cathode [12].…”

“…Most ferroelectric cathode experiments have been performed using cathodes with a diameter of 2-4 cm and a thickness of 1-2 mm [1][2][3][4][5][6][7][8][9]. The currents that have been obtained are of the order of tens of amperes [1][2][3][4][5][6][7][8][9] with current densities of order 10-100…”