where the beam radius sizes were of the order of one
centimeter. Additionally, small size foilless diodes were
successfully installed at the front end of HERMES III and
SABER [10] (Figures 1- 4) for mm sizes flash x-ray
radiography. Although the radiographic experiments with
HERMES III and SABER generated millimeter size
beams, the short distance between cathode tip and
convertor bremsstrahlung target (smaller than 10 cm)
caused diode impedance collapse at about 20-30ns in the
voltage pulse.