Traveling-wave tube with oscillation prevention means

Claim 1

A TRAVELING-WAVE TUBE COMPRISING: MEANS FOR PROVIDING A STREAM OF ELECTRONS ALONG A PREDETERMINED PATH, AN ELECTRICALLY CONDUCTIVE ENVELOPE DISPOSED ABOUT AND AXIALLY ALIGNED WITH SAID PATH, A PLURALITY OF ELECTRICALLY CONDUCTIVE PLATES MOUNTED PERPENDICULAR TO SAID PATH AT SPACED POINTS ALONG SAID ENVELOPE TO DEFINE THEREWITH A PLURALITY OF CAVITIES, SAID PLATES DEFINING ALIGNED APERTURES IN THEIR CENTRAL REGIONS TO PROVIDE A PASSAGE FOR SAID ELECTRON STREAM AND FURTHER DEFINING COUPLING APERTURES IN REGIONS RADIALLY OUTWARDLY OF SAID CENTRAL REGIONS FOR INTERCONNECTING ADJACENT CAVITIES WHEREBY A PROPAGATION PATH IS PROVIDED FOR ELECTROMAGNETIC WAVE ENERGY WITHIN A PREDETERMINED FREQUENCY RANGE IN A MANNER TO PROVIDE ENERGY EXCHANGE BETWEEN SAID ELECTRON STREAM AND SAID ELECTROMAGNETIC WAVE ENERGY, EACH OF SAID PLATES DEFINING A FIRST TUBULAR PORTION ADJACENT ITS CENTRAL APERTURE WHICH PROJECTS BEYOND THE REMAINDER OF SAID PLATE ON AT LEAST ONE SIDE THEREOF IN A DIRECTION ALONG SAID ELECTRON STREAM PATH AND A SECOND TUBULAR PORTION OF THE SAME INNER CIRCUMFERENCE AND SMALLER OUTER CIRCUMFERENCE THAN SAID FIRST TUBULAR PORTION PROJECTING BEYOND SAID FIRST TUBULAR PORTION IN SAID DIRECTION WHEREBY AN INTERACTION REGION IS PROVIDED IN THE CAVITY INTO WHICH SAID FIRST AND SECOND TUBULAR PORTIONS PROJECT OF AN AXIAL LENGTH LESS THAN THE AXIAL LENGTH OF SAID CAVITY, AT LEAST A PAIR OF ELECTRICALLY CONDUCTIVE SUPPORT ELEMENTS RESPECTIVELY AFFIXED TO THE FIRST TUBULAR PORTIONS OF THE PLATES DEFINING SAID CAVITY, SAID SUPPORT ELEMENTS PROJECTING FROM SAID FIRST TUBULAR PORTIONS ON OPPOSITE SIDES OF SAID ELECTRON STREAM INTO SAID CAVITY, AND AN ELECTRICALLY CONDUCTIVE RING MOUNTED ON THE ENDS OF SAID SUPPORT ELEMENTS REMOTE FROM SAID FIRST TUBULAR PORTIONS, SAID RINGS BEING CONCENTRICALLY DISPOSED ABOUT SAID ELECTRON STREAM IN A PLANE PERPENDICULAR TO SAID ELECTRON STREAM PATH AND HAVING A CIRCUMFERENCE EQUAL TO A PRESELECTED WAVELENGTH CORRESPONDING TO A FREQUENCY WITHIN SUBSTANTIALLY SAID PREDETERMINED FREQUENCY RANGE.