Investigations of the radial-electron-beam diode for gas-laser excitation

A study has been made of high-power radially converging electron-beam diodes and their application to gas-laser excitation. The REBLE accelerator, built for this study, provided reliable single-shot operation at the 1-MV 180-kA 20-ns level. It is shown that annular-blade cathodes can produce uniform anode current densities at 100–200 A/cm2. Apertured-Faraday-cup measurements indicate that the beam is transported readily through the gas. No evidence of microinstabilities in the anode current density were observed. Comparisons of energy-deposition measurements and calculations demonstrate that existing Monte Carlo electron/photon transport codes give an accurate description of the energy deposition when collective effects are not important. Measurements of zenon-excimer radiation excited by the radial electron beam show that 20% of the electron-beam energy deposited in the gas appeared as excimer light. At ∼1600 Torr the radial profile of the emitted radiation was uniform within the ±10% uncertainty in the measurement.