Secondary emission electron gun for high pressure molecular lasers

A high-voltage large-area electron gun is described. Ions are generated in a low-pressure ion source, extracted by a grid, and accelerated by a -130-kV continuously biased electrode. By secondary emission, these ions produce electrons which are accelerated toward the grid. They go through the ion source and an electron window (15 x 5 cm). Electron-beam density profiles display a good uniformity. The current density, limited only by the available power for the discharge, presently reaches 1 mA/sq cm. The advantages of this gun over others are moderate vacuum requirements and capability for both low-current CW and high-current pulsed beams with easy control at ground potential and small energy requirement.