Ion Microbeam Source
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
A typical electron-bombardment ion source is shown in Fig. 1. The gas to be ionized is introduced into the outer shell 2 of the ion source. Energetic primary electrons are emitted by the cathode 3. At the low pressures normally of interest, the primary electrons would rapidly escape to the anode 4, except for the magnetic field lines 5 between the anode and cathode. The primary electrons process around the axis of the discharge chamber (the volume enclosed by the anode 4 and the ends of the outer shell 2) until collisions permit them to cross the magnetic field lines. Some of the collisions generate ions, which, if they reach the aperture 6, can be extracted by the negative potential on electrode 7. The ions of interest pass through aperture 8 and become the departing ion beam 9.