A univoltage ion gun design

A broad beam ion gun has been designed and tested that requires only a sing le high voltage supply. It creates 1-2-mm-diameter 2-10 kV beams that are v isually uniform in spatial intensity with a sharp edge cutoff using a Perrh enate solid state ion source. The gun's electrode geometry is designed to m ake beam diameter independent of acceleration voltage. Moreover, the source is imaged at the focal length of the acceleration optics to obtain a beam with visually uniform spatial intensity. With this approach, all points on the source's emission surface contribute equally to the brightness of each point in the beam. The univoltage ion gun design has demonstrated its utili ty in broad beam static secondary ionization mass spectrometry (SIMS) instr uments and is being adopted as the ion gun of choice for many of our group' s instruments. (C) 1999 Elsevier Science B.V.