Low-Energy Accelerators of Large Cross-Section Electron Beams with the Extraction into the Atmosphere (A Review)

A large array of experimental data on the extraction of large cross-section electron beams into the atmosphere using low-energy (80–300 keV) electron accelerators has been analyzed. The electron accelerators considered are based on various emission types: thermionic emission, explosive electron emission, different plasma-cathode discharges, and a high-voltage glow discharge. The “large area effect” has been retrospectively demonstrated and quantified, which consists in reducing the maximum current density of an electron beam extracted into the atmosphere with an increase in the cross-sectional area of the beam, but while maintaining stable generation conditions. Based on the data analysis, it is shown that there is a technological constraint on the average power density of large cross-section electron beams generated by low-energy electron accelerators, which is as high as 40 W/cm2. This constraint is associated with the resistance of thin foils for extracting electron beams from vacuum into the atmosphere.