HIGH-CURRENT DENSITY ELECTRON-BEAM GENERATION FROM FIELD-EMISSION TIP CATHODES

Electron beams with current up to 1.2 A and current density over 10(7) A/cm2 have been generated from a pulsed field emission tip cathode etched from commercial grade tungsten wire. Electron beams with current up to 0.8 A have also been generated from a molybdenum tip. Tip radius was 0.1-1 mum. Applied tip voltage was up to 50 kV with pulse duration of 0.3-1.2 mus. Depending on brightness, these types of electron beams could be suitable for channeling radiation x-ray lasers and might considerably decrease the operating wavelength of free-electron lasers at moderate beam energies.