[en] The aim of the invention has been the increase of reliability and accuracy of angular distribution measurement of the flux of cosmic plasma. For this purpose into electrostatic analysers consisting of secondary electron mutipliers and the pair of plates oriented in different directions the pair of calibration plates oriented in one side and geometrically conjugated with the same secondary electron multipliers as the working plate pair are introduced. In addition, the staircase voltage calibration source is introduced. The assumed modification permits besides measuring fluxes arriving from different directions to perform in the calibration mode simultaneous measurements of fluxes coming from one direction which allows one to determine relative sensitivity of secondary electron multipliers in different regions of the device energy range. The reliability and accuracy of angular distribution measurements is increased theirwith ten times