Could it be that potential barrier current and contact potential are the same thing on electron tubes?

Or at least having the same cause.


After all these effects take place because electrons leave a material to go somewhere else.


Potential divided by current gives resistance:


Would contact potential divided by potential barrier current have a physical meaning?


Put more simply:


When we heat the cathode of an electron tube we can measure the grid and other electrodes becoming negative with respect to the cathode. (This is why we need pull up bias in order to operate the electron tube at say only 4 volts to the plate, see Pleiades V6 amplifier).


If we connect a microammeter between anode and cathode (no anode supply) or between grid and cathode we measure a current.


This is all done by the emitted electrons from the cathode having, velocity, therefore kinetic energy.


See also:


Epstein's minimum potential and


Fundamentals or radio-valve technique - Deketh - Philips Technical Library - chapter 1 to 5