METHOD OF MEASURING RATE OF EVAPORATION OF ACTIVE SUBSTANCE FROM SURFACE OF THERMIONIC CATHODE Russian patent published in 2024 - IPC H01J9/42 G01R31/24 

FIELD: electronic equipment.

SUBSTANCE: invention relates to electronic engineering, in particular to methods of measuring the rate of evaporation of an active substance from the surface of thermionic, in particular, metal-porous cathodes. Thermionic cathode pre-pyrometered at different filament voltages is placed in a vacuum chamber axially symmetric to the surface of the piezoelectric plate of the quartz generator at a distance of at least 40±1 mm from the surface of the piezoelectric plate. Electrodes are connected to it from a stabilized power source for supply of filament voltage and resonant frequency of oscillations ƒ₀ of piezoelectric plate of quartz generator is recorded. Filament voltage corresponding to the required temperature of the cathode is supplied and held for a time Δt. Then the power supply is disconnected for cooling the thermionic cathode and the piezoelectric plate, the changed oscillation frequency of the piezoelectric plate is measured ƒ₁, then calculating difference of measured resonance frequencies Δƒ=ƒ₀-ƒ₁ and determining the rate of deposition of the active substance on the surface of the piezoelectric plate averaged over a given period of time Δm/Δt. Rate of evaporation of the active substance from the surface of the thermionic cathode is determined taking into account the sputtering coefficient K, which takes into account the active substance evaporated from the surface of the cathode and not falling on the piezoelectric plate, by the ratio: Dependence of the rate of evaporation of the active substance on the operating time of the thermal emission cathode is also measured.

EFFECT: higher accuracy of measurement of evaporation rate and reduced duration of measurements in comparison with other known methods of measurement of evaporation rate.

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