Magnetic structure for traveling wave tubes

Claim 1

IN A DEVICE OF THE TRAVELING WAVE TUBE TYPE WHICH INCLUDES AN ENVELOPE HAVING THEREIN MEANS FOR PRODUCING AN ELECTRON BEAM FOR FLOW ALONG A GIVEN PATH, A RADIO FREQUENCY PROPAGATING STRUCTURE DISPOSED ADJACENT SAID PATH TO ENABLE INTERACTION BETWEEN THE ELECTRONS OF SAID BEAM AND SAID RADIO FREQUENCY ENERGY PROPAGATED ALONG SAID STRUCTURE, AND AN ELECTRON COLLECTING MEANS DISPOSED AT THE OPPOSITE END OF SAID PROPAGATING STRUCTURE WITH RESPECT TO SAID BEAM PRODUCING MEANS, A MAGNETIC STRUCTURE POSITIONED ABOUT SAID ENVELOPE FOR FOCUSING AND CENTERING SAID ELECTRON BEAM WITHIN SAID PROPAGATING STRUCTURE COMPRISING A CYLINDRICAL CORE OF MAGNETIC MATERIAL CONCENTRIC WITH RESPECT TO THE AXIS OF SAID BEAM AND EXTENDING ALONG THE LENGTH THEREOF, END POLE PIECES AT THE ENDS OF SAID CORE AND TRANSVERSE TO SAID AXIS, SAID ENVELOPE POSITIONED WITHIN OPENINGS PROVIDED IN SAID POLE PIECES, MAGNETIC SHUNT MEANS SURROUNDING SAID CYLINDRICAL CORE HAVING PINS EXTENDING RADIALLY INWARD AND CONTACTING SAID POLE PIECES TO THEREBY DISPLACE SAID SHUNT ECCENTRICALLY IN A TRANSVERSE DIRECTION TO POSITION THE MAGNETIC FIELD AXIS OF SAID CORE IN REGISTRATION WITH SAID ELECTRON BEAM PATH.