Long-Life High-Current-Density Cathode for Low-Convergence Electron Beam Guns

High Power Vacuum Electron Devices (VEDs) used in military radar, electronic attack, and in both military and civilian communications systems as well as the high power physics community require electron beam currents in the range from a few to several tens of amperes, pulling from typical thermionic cathodes from 5 to 20 amps/cm2 (A/cm2). Existing dispenser technologies provide 2 - 4A/cm2 with relative ease. As one approaches the upper end of emission, 4 A/cm2 and higher, life of the cathode and device are reduced. Novel approaches to increased emission include changes from Spectra-Mat, Inc.’s (SMI) well-proven scandia-mixed impregnant and/or creating an improved coating for dispenser cathodes. SMI proposes to design, manufacture and test prototype cathodes of formulations of mixed small diameter (1 micron or less) tungsten (W) and scandium oxide (scandia, Sc2O3) powders, pressed and sintered into an 80% dense matrix and impregnated with 612 barium-calcium-aluminate. SMI also proposes a standard powder 612 cathode coated with a proprietary formulation of tungsten and rhodium. The combined effort utilizes our unique and extensive experience in manufacturing cathodes, calcining molar ratio impregnant mixtures including scandia and sputter coating finished cathodes in an innovative manner to create high emission cathodes