Electron gun in the form of a multipactor

Claim 1

IN AN ELECTRON GUN COMPRISING AN ENVELOPE, A PAIR OF SPACED-APART ELECTRODES THEREIN, A FIRST OF SAID ELECTRODES BEING ADAPTED TO EMIT SECONDARY ELECTRONS ON IMPACT BY A PRIMARY ELECTRON, A SECOND OF SAID ELECTRODES HAVING AN APERTURE THROUGH WHICH ELECTRONS MAY FLOW, MEANS FOR CONVERGING SAID ELECTRONS TOWARD SAID SECOND ELECTRODE IN THE VICINITY OF SAID APERTURE, SAID MEANS INCLUDING A CONCAVE SURFACE ON SAID FIRST ELECTRODE, AN INTERMEDIATE ELECTRODE HAVING A CONICALLY SHAPED OPENING TAPERING TOWARD SAID APERTURE, AN OSCILLATORY CIRCUIT CONNECTED TO SAID PAIR OF ELECTRODES, MEANS FOR SUPPLYING ALTERNATING CURRENT TO SAID OSCILLATORY CIRCUIT TO CAUSE SAID ELECTRONS TO OSCILLATE BETWEEN SAID PAIR OF ELECTRODES AND TO MAKE REPEATED SECONDARY ELECTRON-GENERATING IMPACTS WITH SAID FIRST ELECTRODE AND CAUSE A PORTION OF SAID ELECTRONS TO PENETRATE SAID APERTURE.