Curtain gas filter for high-flux ion sources

摘要

A curtain-gas filter for a mass- or mobility-spectrometer that bars gases or vapors of a high-flux atmospheric pressure ion source, as we ions of high mobility and charged droplets, from entering an evacuated mass spectrometer or a mobility spectrometer that is at a lower pressure than the main filter volume of the curtain-gas filter. A portion of the ion-source buffer gas in the ion-source plume is sucked through an ion-source buffer gas inlet into the main filter volume of the curtain-gas filter, from where this ion-source gas is exhausted after a properly shaped electric field has pushed a large portion of the embedded ions into an externally provided stream of a clean buffer gas, which is sucked through a passage into a mass- or mobility-spectrometer that is at a lower pressure.

主权项

1. A spectrometry system, comprising:
an ion source that produces an ion-source plume; an ion-source buffer-gas inlet configured to receive ion-source buffer gas from said ion-source plume; a clean buffer-gas inlet configured to receive a clean buffer gas from an external source; and a curtain-gas filter including, at least one first low-turbulence gas guide that transfers said ion-source buffer gas from said ion-source buffer gas inlet to a main filter volume having a gas pressure lower than a gas pressure of said ion-source plume, at least one second low-turbulence gas guide that transfers said clean buffer gas from said clean buffer-gas inlet to said main filter volume, a passage positioned between an ion extraction volume within the main filter volume and at least one spectrometer having a gas pressure lower than the gas pressure in the main filter volume of said curtain-gas filter, and at least two electrodes placed at different potentials to generate an electric field so as to push ions having a range of mobilities from said ion-source buffer gas in said main filter volume into said clean buffer gas in said main filter volume, to generate an ion containing clean buffer gas in an ion extraction volume of said main filter volume, wherein the main filter volume includes the ion-source buffer gas and the clean buffer gas as substantially unmixed flows having a boundary therebetween; and wherein said ion-containing clean buffer gas in said ion extraction volume flows substantially through said passage into said at least one spectrometer, and any remaining gas in a portion of said main filter volume outside of said ion extraction volume is exhausted.