Development of ferroelectric electron beam diodes

Summary form only given, as follows. We are currently investigating the use of ferroelectric ceramics for electron beam generation. These materials exhibit a spontaneous (saturation) polarization, P/sub s/, of up to 100 /spl mu/C/cm/sup 2/. Emission occurs when the polarization state of the ferroelectric is changed rapidly by an applied electric field, and a fraction of the surface screening charge is released at a gridded electrode. Using a lead-zirconate-titanate (PZT) ceramic as the electron source in a planar 14 kV diode geometry we have measured diode current densities of up to 40 A/cm/sup 2/ with a 5n gap. The normalized rms emittance of this beam has been measured to be 12/spl pi/ mm-mrad at 8 A. Recent results from experiments to extend operation of this diode up to 70 kV, 300 ns pulses will be reported. We are also designing a 20-30 kV, 1 /spl mu/s system that will be operated in a repetition rate mode. We are planning to use such a system as part of our program to develop compact X-band sources with average power levels in the hundreds of watts range. Using simulation codes, such as EGUN, together with results from analytical work TWT structures are being designed for use with these sources. The advantages of using PPM focusing in both cylindrical or sheer beam configurations are also under investigation.