AUTOMATIC GAIN CONTROL WITH DEFOCUSING LENS

摘要

A method and apparatus for performing mass spectrometry using an electron source, an ion trap, and a voltage-controlled lens located between the electron source and the ion trap. A controller applies a voltage to the lens. Features of the resulting output spectrum can be analyzed to determine whether to adjust the lens voltage.

主权项

1. A mass spectrometer for analyzing sample molecules, comprising:
an electron source, configured to emit electrons; an ion trap for receiving the emitted electrons, such that the received electrons ionize one or more sample molecules in the trap; an ion detector for detecting ions exiting from the ion trap; and a controller, including:
a first voltage-controlled lens located between the electron source and the ion trap, wherein the first lens has an aperture configured to allow the emitted electrons to pass through the first lens and enter the ion trap, and wherein the first lens is configured to adjust a rate by which the electrons enter the ion trap based on a voltage applied to the first lens; anda voltage controller configured to apply a voltage to the first lens.