[en] The description and results of investigations into a mass-spectrometer for the study of fast gas phase processes are presented. The mass spectrometer consists of a system of preparing a gaseous mixture, a reactor, a system of sample introduction from a reactor in the ionization region; the system of differential pumping-out; ion sources with the ionization with an electron shock; a 180-degree magnetic analyzer; ionoelectron optic converter, the registration system. The fast action of the device is 10^-5 s. The maximum pressure in the reactor is 1.3x10⁴ Pa in the range of ionization and 1.3x10^-4 Pa - in the analyzer. The distance between the intake top to the beginning of the Diffusion coefficients of ⁶³Ni radioactive isotope on the boundaries of γ/γ' phases in a heat-resisting nickel base alloy, are measured. The diagram of the method of measuring the diffusion coefficients, is presented. Using the methods of autoradiography, ⁶³Ni distribution in the grain volume is investigated. It is shown that inhomogeneity of grain distribution is connected with increased diffusion permeability of γ/γ' phase boundaries. The temperature dependence of nickel diffusion coefficient in the volume and γ/γ' phase boundaries, is given. It is noted that in the range of 700-1000 deg C nickel diffusion coefficients in γ/γ' phase boundaries are 2-3 orders higher than the value of diffusion coefficient in the phase volume. The activation energy of nickel diffusion in boundaries of γ/γ' phases E and preexponential multiplier D₀¹:E¹=70000 cal/mol and D₀¹=5x10² cm²/s, are determined according to the temperature dependence of diffusion coefficients