A COUPLED RESONATOR REFLEX KLYSTRON 



719 



suit of these derivations, however, and its physical significance will be 

 discussed at some length. 



2.1 Electronic Admittance 



Consider an arrangement of four plane and parallel elements consist- 

 ing of a cathode, two ideal grids and a reflector. Assume these electrodes 

 to be of infinite extent so that all electrons will move in straight paths 

 perpendicular to the planes of the electrodes. Let the current densities 

 encountered be low enough so that space charge effects can be neglected. 

 Both grids are operated at the same dc potential, Vo , positive with respect 

 to the cathode. As shown in Fig. 1, this might be achieved by connecting 

 them to the secondary winding of an ideal transformer having a 1:1 

 turns ratio. The reflector is operated at a dc potential, Vr , negative with 

 respect to the cathode. Next, an RF voltage of amplitude V is applied 

 to the transformer and, hence, appears across the grids. Electrons emitted 

 from the cathode are accelerated toward the first grid and arrive at it 



CATHODE 



RF VOLTAGE OF 

 AMPLITUDE, V 



REFLECTOR 



DC POTENTIAL 

 PROFILE 



Fig. 1 — Electrode arrangement and dc potential profile giving rise to elec- 

 tronic admittance, Ye , described by equation (2.1). 



