Transit time and space charge in a plane diode

A mathematical treatment is given of the problem of transit time and space charge effects in a plane diode, formulae being derived applicable to the beginning of an electronic discharge, as well as for the current/voltage relation during the discharge if the transit times are not too large. This is followed by a discussion of the effects at the end of an electronic discharge, where negative anode potentials will push the space charge back towards the cathode, and a discussion of the dispersion of transit times in a vacuum tube (a) without space charge and (b) with space charge effects. From this it is seen, among other things, that the efficiency of tubes with large space charge effect should decrease continuously with increasing frequency.