Abstract : Results are presented for a program to validate the technology for thermionic field emission (TF) guns. TF guns are proposed as an attractive alternate to cold cathode guns as high average and high peak current density excitation sources for repetitively pulsed short wavelength lasers. Among the advantages of TF guns are that they exhibit temporally constant impedance characteristics, are not subject to diode closure restrictions, and utilize well understood and controllable electron trajectories. The latter requirement is critical to the achievement of efficient beam transmission through closely spaced cooled ladder and foil support structures. Major program tasks included: performance of a theoretical analysis to predict the emission characteristics for a diode experiment and to estimate achieveable beam uniformity; development and thermal testing of a filament and support structure suitable for large area guns; and design, construction and experimental evaluation of a small area high voltage TF gun.