Emission from ferroelectric cathodes

Abstract

We have recently initiated an investigation of elecii .. llii i This work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under contract no. W-7405-Eng-48.

Influence of pulse polarity on electron emission property of antiferroelectric ceramic

“…As a novel cathode, ferroelectric cathodes have a number of advantages over other conventional cathodes such as field emission cathodes, thermionic cathodes etc. [1][2][3][4][5][6][7][8][9][10][11] . They are as follows: (i) They can produce highcurrent-density beams, and emitted current densities are above those determined by the Child-Langmuira [1][2][3] .…”

“…[1][2][3][4][5][6][7][8][9][10][11] . They are as follows: (i) They can produce highcurrent-density beams, and emitted current densities are above those determined by the Child-Langmuira [1][2][3] . (ii) They are able to produce uniform electron beams with low beam divergence and high enough brightness (10 9 -10 11 A/(m 2 ·rad 2 )) [3][4][5] , without delay of the beam appearance with respect to the accelerating voltage application.…”

“…(iv) Emission electron is energetic and has been measured to be as high as several keV without an external accelerating field [6,7] . (v) Room temperature operation, control of the emission by an external trigger pulse [1][2][3][4] . These features make ferroelectric cathodes very promising for applications in the field of powerful microwave devices like gyrotrons, magnetrons, and traveling wave tubes [8][9][10][11] .…”

Self-bunching electron guns

“…The first involves a phase transition from ferroelectric to antiferroelectric state [35,36]. The second involves rapid changes in the ferroelectric state [37][38][39][40][41][42] but does not involve a phase transition. The former can be described by considering the free charge that exists on the surface of a pre-poled ferroelectric cathode.…”

“…PLZT) from an antiferroelectric to a ferroelectric state [35,36], and in other cases by cycling a ferroelectric material (e.g. PZT) around a minor hysteresis loop [37][38][39][40][41][42]. Beam currents up to 350 A and electron energies in the range of 200−550 keV with pulses in excess of 200 ns have been achieved [43].…”