Ion Collection in Bayard–Alpert Gauges

Abstract

The theoretical dependence of the ion collection in Bayard–Alpert gauges (BAG) with open-end grid on ion initial energy, ion “birth place,” geometrical and electrical parameters, is briefly presented. The resulting consequences concerning the behavior and the main features of BAG as well as the expected values of the collection factor are compared with available experimental data. The results of this comparison and the peculiarities of the ion collection in BAG with closed-end grid are analyzed. Finally, the practical consequences concerning two distinct application areas of the BAG are discussed: (a) the total pressure measurements and (b) the utilization of the very high sensitivity of the ion collection with respect to the initial ion velocities for thermal and subthermal ion velocity spectrometry (e.g., for the measurement of momentum transfer at charge exchange and at ionization with slow electrons).