Background components of a small-energy charged particle spectrometer during measurements in cosmic space

Components of charged particle spectrometer background, in which selection in energies is realized by electrostatic analyzer, and an open secondary-electron multiplier is used as a detector, are studied. It is shown that the spectrometer background considerably exceeds the average value in the region of radiation belts at higher intensities in zones of aurora, as well as in case of orientation of electrostatic analyzer inputs to the Sun. Accordingly, the background was conditioned: in the ranges of radiation belts - by charged high-energy particles, bremsstrahlung and secondary electron and ion emission, in zones of aurora - by charged particles, in case of direct orientation to the Sun - by ultraviolet radiation, and in case of oblique incidence of ultraviolet radiation on the inputs of electrostatic analyzers the main contrubution to the background can be made by photoelectrons