Microwave cold cathode magnetron with internal magnet

Claim 1

IN A MAGNETRON MICROWAVE TUBE APPARATUS; MEANS FORMING A GENERALLY CYLINDRICAL CATHODE ELECTRODE STRUCTURE; MEANS FOR PRODUCING AN ARCUATE STREAM OF ELECTRONS ADJACENT SAID COLD CATHODE ELECTRODE; MEANS FORMING AN ANODE ELECTRODE STRUCTURE COAXIALLY DISPOSED OF SAID CATHODE ELECTRODE IN SPACE APART RELATIONSHIP AND DEFINING AN ELECTRONIC INTERACTION REGION THEREBETWEEN, SAID ANODE ELECTRODE INCLUDING AN ARCUATE WAVE CIRCUIT FACING SAID CYLINDRICAL CATHODE ELECTRODE STRUCTURE FOR ELECTRONIC INTERACTION BETWEEN WAVES ON SAID CIRCUIT AND THE STREAM OF ELECTRONS; MEANS FORMING A PERMANENT MAGNET DISPOSED WITHIN SAID CATHODE ELECTRODE FOR GENERATING AN AXIALLY DIRECTED MAGNETIC FIELD IN SAID INTERACTION REGION TO CAUSE THE ELECTRON STREAM TO MOVE TANGENTIALLY TO SAID WAVE CIRCUIT TO EFFECT CUMULATIVE ELECTRONIC INTERACTION BETWEEN THE ELECTRON STREAM AND WAVES ON SAID ANODE CIRCUIT; MEANS FOR EXTRACTING MICROWAVE ENERGY FROM SAID CIRCUIT, MEANS FORMING AN EVACUABLE ENVELOPE ENCLOSING SAID MAGNET, SAID CATHODE AND THE MAGNETRON INTERACTION REGION, THE IMPROVEMENT COMPRISING, MEANS FORMING A PAIR OF MAGNETIC POLE PIECES DISPOSED WITHIN SAID EVACUABLE ENVELOPE AT THE ENDS OF SAID PERMANENT MAGNET, SAID POLE PIECES PROJECTING TOWARD SAID ANODE ELECTRODE STRUCTURE AND OVERHANGING THE SIDES OF SAID PERMANENT MAGNET TO IMPROVE THE UNIFORMITY OF THE MAGNETIC FIELD IN THE MAGNETRON INTERACTION REGION.