Production and analysis of lithium ion beams in the low electron volt region.

摘要

A lithium ion source capable of delivering low energy,monoenergetic beams of rectangular cross section, has beendeveloped for use in the study of low-energy atomic, ionic, andmolecular impact phenomena. An analysis of the spatial and energydistribution of the ion beams extracted from the source was madeover the range of ion energies from 1.2 ev. to 100 ev, with particularattention given to beams with energies less than 25 ev. The experimentalequipment and procedures are described. For the beams oflow energy the intensity of the beam was limited by the space charge.The beam intensity in this space charge limited condition wasapproximately one third of the theoretical limit. Total beam—8intensities ranged from a few times 10" amps at the lowest energiesto a few times 10" amps at the higher energies with correspondingenergy spreads of 1 .1 eV to * 0*3 eV. Typical beam dimensionsare 1.0 cm by 2.0 cm at a distance of 5.0 cm from the gun with anaperture 0.47 cm by 1.5 cm.