A compact low-energy electron beam irradiator

A new compact low-energy electron beam irradiator has been developed. The irradiator generates an electron beam to the air with energy variable from 35 to 80 keV and with a maximum current of 1 mA. The irradiation area is 30×30 mm2. A special irradiation port is developed for this low-energy irradiator. The electron beam is generated from a thermionic LaB6 cathode in vacuum. The beam is extracted to the air through a havar foil window. The thickness of the window is 4.8 μm, it is vacuum-tightly connected to the window to support by an indium wire. A controlled bow geometry of the window helps the thin window withstand the vacuum pressure. Cold air generated from a vortex tube cools down both the window and its support in order to prevent the window from melting down, due to beam energy dissipated in the foil. We found that about 60% of the beam current is extracted to the air at 80 keV.