Generation of contaminant-like beams for magnetic spectrometer characterization

Abstract

Characterizing a (high resolution) magnetic separator may not be easy as it is difficult to find a stable ion source providing species with close enough masses to separate. As these instruments perform a momentum separation (Bρ=p/q), their mass and energy resolution are strictly the same. One can use this property to characterize the mass resolution of a spectrometer through its energy resolution. Hence, multiple identical beams with close energies can be used to test a magnetic spectrometer in almost real conditions. The method we present allows to populate an ion beam with multiple close and well-defined energies. It consists in using an arbitrary pulse generator to temporally change the acceleration potential of the ion source, and create a custom energy distribution, where the length in time of the pulse is the production ratio of the contaminant and the amplitude its relative energy (i.e. its mass).