Abstract
Measurement was made of the electron emitted from the oxide-coated cathodes in the directly heated rectifier during both the normal and the accelerated life test.
The accelerated life test was made by applying cathode voltage 10% higher than the normal rating. The emitted current was measured by two methods, the measurement of the component dc of the current put out Io and the measurement of the dc saturated in the emission Is.
It seems that the most effective and shortest life test in the evaluation of the cathodes in rectifier on the quality level is the measurement of Is at accelerated life test.
It was found in the above mentioned life test that increase of oxide-coating was effective to prevent decay in the emission of electron.
Addition of nickel powder into oxide coating was effective to prevent rectifier from sparking between anode and cathode and gave no harmful influence on electron emission from cathode.
