XV.An alternating current method for collector analysis of discharge-tubes

Summary An alternating current method is described which enables the second derivative of the current-voltage curve of an auxilliary electrode in a gaseous discharge to be obtained directly, provided the discharge conditions are sufficiently stable. This obviates the necessity for double graphical differentation of the ordinary electron current-voltage curve when the second derivative id required for substitution in Druyvesteyn's distribution equation for electron speeds. The definition and determination of the space potential are discussed at length, and it is shown that the most reasonable point to take in this connexion is that the most reasonable point to take in this connexion is that at which the second derivative is zero. This point can be obtained by the present authomatic methos with considerable accuracy. Typical curves are shown to illustrate the application of the method to actual cases.