| 摘要 |
FIELD: vacuum electronics. SUBSTANCE: in agreement with proposed nondestructive testing method flickering component of noise is measured with fixed frequency f, rejected and current picked off cathode is set by change of positive voltage across anode. In this case all other electrodes have zero potential. Anode voltage corresponding to each value of current is measured, perveance is computed, ratio of measured flicker-to-noise level for each set current to perveance is determined. Similar sequence of operations is carried out with flat diode which has cathode of same type. Measurements are conducted with same values of density of cathode current Jkn. Coefficient Kn(f, Jkn) of cathode quality is found for each value of this current. Several tested cathodes are subjected to operating time tests. Degree of drop of cathode current is determined by results of these tests. Set of limiting values of coefficient of cathode quality Kn(f, Jkn)lim is found for specified limiting value of this drop. Rejection is conducted by comparison of coefficients of quality. Cathodes for which there are realized conditions: K(f,j) ≅ (K(fj))...K(fj) ≅ (K(f,j))are considered to be good. Tested instrument is connected into circuit providing flow of constant current Ipicked off cathode and going to anode. Noises of cathode current crease with the help of resistor noise voltage on it which is amplified by amplifier and fed into filter. Readings of output instrument 12 are recalculated to values of spectral density. EFFECT: increased authenticity and simplification of quality test of cathodes. 5 dwg |
