. The Bell System technical journal . fication factor. However, theratio of the two, namely, a/z, maintains a fairly constant magnitudeas shown in Fig. 7, whose phase angle nevertheless rotates continuallym a negative direction becoming equal to 3 radians when t is 27r. The interelectrode capacity between cathode and plate is includedm the fundamental relations here employed. This inclusion exhibitsone important difference between (32) and the classical case. At lowfrequencies, the equivalent circuit represented by (32) degenerates intothat shown on Fig. 8. The capacity branch exists in parall
. The Bell System technical journal . fication factor. However, theratio of the two, namely, a/z, maintains a fairly constant magnitudeas shown in Fig. 7, whose phase angle nevertheless rotates continuallym a negative direction becoming equal to 3 radians when t is 27r. The interelectrode capacity between cathode and plate is includedm the fundamental relations here employed. This inclusion exhibitsone important difference between (32) and the classical case. At lowfrequencies, the equivalent circuit represented by (32) degenerates intothat shown on Fig. 8. The capacity branch exists in parallel with the 76 BELL SYSTEM TECHNICAL JOURNAL resistive branch and they are both in series with the effective generatoro-gp, whereas in the classical picture the capacity branch shunts theeffective generator and plate resistance which are in series with eachother. Practically the difference between the two equivalent circuitsis negligible except at extremely high frequencies. The followingphysical viewpoint supports the newer Fig. 7—Magnitude of complex mutual conductance of negativegrid triodes versus transit angle. As pointed out, the action of the grid is exerted mostly on the regionof dense space charge existing very near the cathode and variationsin the grid potential act on the velocities of the emerging electrons,thus producing the equivalent generator of the plate circuit. Theplate current consists of conduction and displacement componentswhose sum is the same at all points in the cathode-plate path. Nearthe cathode, the conduction component comprises the whole currentbecause of the high charge density and the effective generator acts inseries with this current and hence in series with the path of the dis-placement current into which the character of the total current gradu-ally changes as the plate is approached. Strictly speaking, the equivalent circuit corresponding to (32) ex-ists, not between the plate and cathode, but between the plate andthe potential
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