Ion source with longitudinal ionization of a molecular beam by an electron beam in a magnetic field

A high-efficiency ion source for a mass-spectrometer's detector of molecular beams and their scattering products is described. The ion source is designed according to a scheme of impact ionization of a beam particle by a longitudinal electron beam in a magnetic field with a strength of up to 130 mT. The design of the source developed is very flexible and has no limitations for use in any experiments with molecular beams. An ionization efficiency of particles of an atomic helium beam of 10(-3) ions/atom has been achieved. The useful signal-to-background ratio in the detector's chamber is 3 x 10(4) during detection of ions with mass-to-charge ratio m/q = 4 amu.