Long time current stability of a gas field ion source with a supertip

Abstract

A gas field ion source with a fine protrusion, a 'supertip', on top of a W (111) emitter tip has been operated for a period of 170 h at an angular current density of 8 mu A sr-1 He+. The current stability, at a level of 2.5 nA, has been found to be typically of the order of +or-1%, with very little occasional need for operator intervention.