Patent ID: 6472881
Filing Date: 2002-10-29
Classification: H01J

Abstract:
In a liquid metal ion source having an extraction electrode and a suppression electrode for extracting metal ions from a liquid metal coating on a tip of an emitter electrode by causing a focused electric field to be generated at the tip of the emitter electrode:storage means for storing a function defining a relationship between an amount of variation (&Dgr;Ie) in current of the emitter electrode and variation (&Dgr;Vsup) in a voltage of the suppression electrode as a function &Dgr;Ie=F(&Dgr;Vsup), with the voltage Vext of the extraction electrode being at a fixed value; detection means for detecting the variation &Dgr;Vsup in the voltage (Vsup) of the suppress ion electrode when a voltage Vext of the extraction electrode is made to vary by only &Dgr;Vext with the current of the emitter electrode being fixed; and calculation means for calculating flow impedance &Dgr;Vext/&Dgr;Ie using the voltage variation amounts &Dgr;Vext and &Dgr;Vsup acquired by the detection means and the function acquired from the storage means.