Ion source with magnetic field for time-of-flight mass spectrometry

A new ion source for the time-of-flight mass spectrometer (TOFMS) with electron-impact ionization and built-in permanent magnet for electron-beam focusing is described. The focusing of electrons in a homogeneous field leads to an increase in the resolving power and sensitivity of the TOFMS. A spectrometer with the proposed source can operate at electron energies within the 7–100-eV range. The method of suppressing spurious lines in the mass spectrum is described, which is based on a decrease in the energy of ionizing electrons.