Abstract: A method and apparatus for collimating ions being emitted from a supersonic expansion nozzle for injection into a time of flight mass spectrometer. Radio frequency fields are used to focus ions toward a desired path, while energy is dissipated from the ions by using a background gas which is advantageously part of a supersonic expansion, giving the background gas a highly organized velocity profile. The background gas absorbs energy when the ions collide with the background gas molecules. By causing the collisional cooling between the ions and the background gas molecules to occur within the supersonic expansion, the ions do not receive velocity distributions determined by ambient thermal energies, but instead enables generation of a highly collimated and high intensity ion beam directed toward the time of flight mass spectrometer.

Abstract: A high speed data acquisition system which acquires an analog signal, converts it to digital data, and compresses the large volume of accumulated data into a format that can be handled in a microcomputer environment. The data acquisition system of the present invention can rapidly and continuously acquire and process large volumes of data. Included is an averaging circuit which allows the present invention to efficiently process and store large amounts of data uninterruptedly. The present invention is thus well suited for applications that require uninterrupted high-speed sampling over long periods of time.