Fast atom bombardment gun assembly

Exhibit no. 255

The FAB gun is a device that generates the beam of fast moving atoms and directs it onto a liquid target. In the gun, inert gas atoms like argon or xenon are ionized using electrons, the ions are accelerated by an electric potential and collided with other inert atoms. Charge exchange takes place, which results in a beam of atoms having about 8 keV of translational energy. Pictured is a saddle field cold cathode gun developed by Ion Tech Ltd which can be operated up to 10 kV.  The beam emerging from the gun is concentrated about the axis within 2 mm diameter. A deflector plate mounted near the beam exit aperture removes any ions emerging with the neutral beam.