Improvement of the output characteristics of magnetrons using the transparent cathode

The output characteristics of magnetrons can be significantly improved by using a cathode that is transparent to the synchronous electromagnetic fields thereby providing improved conditions for fast conversion of the electrons' potential energy into electromagnetic energy. The transparent cathode consists of separate longitudinal metal strips, arranged to form a cylindrical surface, that act as individual electron emitters. Favorable prebunching of electrons to excite the desired operating mode is provided by a suitable choice of the number and azimuthal position of the cathode strips. The strong azimuthal wave field in the cathode region rapidly captures the prebunched electrons into rotating spokes forming the anode current. This process provides faster start-of-oscillations than priming using a solid cathode. The strong wave field in the electron sheath over the cathode, for any sheath thickness, gives the possibility of improving the efficiency by concomitantly increasing the applied voltage and magnetic field. Computer simulations of the A6 magnetron driven both by a solid and transparent cathode demonstrate the advantages of this approach