Study of a field-ionization source for microprobe applications

Abstract

Operating parameters for a field-ionization source have been measured. Sensitivities of 5×10−5 A sr−1 Torr−1 were found at 77 K. Angular distributions are uniform near ϑ=0° and show the beam to be confined to ±20°. The beam signal-to-noise ratio was found to increase with increasing current. Calculations based on parameters of lenses in use indicate a resolution of 0.1 μm at ≳10−10 A is possible.