Ion source with electron ionization for a portable mass spectrometer

An ion source with electron ionization is considered. The charged-particle flow at the exit from this source has a cross section of $\sim$0.1 $\times$ 0.1 mm, an angle spread of 2$^\circ$ $\times$ 2$^\circ$, a relative energy spread of $<$0.5%, and an energy range of 0.5–3.0 keV. This ion source is intended for systems where an ion beam is focused in two mutually perpendicular directions. The ion source design makes it possible to ionize a sample locally (in a volume of $\sim$10 mm$^3$), where the concentration of the particles under study exceeds the concentration averaged over the volume of the vacuum chamber of the mass spectrometer by two to three orders of magnitude. The ion-optical properties of the source are numerically simulated, and the optimum parameters of the source are chosen. Examples of the application of the ion source are given for the mass-spectrometric determination of metal salts in aqueous solutions and of gases and volatile compounds in samples in various phase states.