Production of sheet electron beams with crossed-field secondary emission diodes

This paper is concerned with the development of a crossed-field secondary emission plane diode that is capable of producing sheet electron beams. Several diode designs having cathode widths of 45-80 mm have been tested and characteristics of output electron beams were investigated. For diode voltages in the 25-40 kV range, the electron beams were generated with currents of 15-45 A and linear current densities of 1-8 A/cm depending on the diode voltage, magnetic field strength, and the diode design. Cathode edge effects were found to be major contributory factors to nonuniformity of the linear current density distributions j (x) but their influence has been greatly reduced by incorporation of axial edge electrodes and downstream reflectors into the diode design and, as a result, +/- 12% uniformity of j(x) has been achieved. It has been shown that generation of thin (a few mm) sheet electron beams of similar to1 m wide with similar to1-5 A/cm current density is feasible.