Traveling-wave tube focusing field straightener

Claim 1

FOR A TRAVELING-WAVE TUBE OF THE CHARACTER INCLUDING AN ELECTRON GUN FOR EMITTING A STREAM OF ELECTRONS AND DIRECTING IT ALONG A PREDETERMINED LINEAL PATH AND HAVING AN ELONGATED SLOW WAVE STRUCTURE DISPOSED ABOUT SAID STREAM AND ALONG SAID PATH IN ELECTROMAGNETIC ENERGY EXCHANGE RELATIONSHIP WITH SAID STREAM AND HAVING A STRAIGHT FIELD FOCUSING MAGNET FOR PROVIDING AN AXIAL FOCUSING AND CONFINING FIELD ALONG SAID PATH AND IN WHICH SAID SLOW WAVE STRUCTURE IS IMMERSED, A FOCUSING MAGNETIC FIELD STRAIGHTENER COMPRISING: HOLLOW TUBULAR BODY MEMBER ADAPTED TO BE DISPOSED OVER SAID TRAVELING-WAVE TUBE CONCENTRICALLY WITH SAID PATH AND WITHIN SAID FOCUSING FIELD; SAID TUBULAR BODY BEING COMPOSED OF SUBSTANTIALLY NONMAGNETIC RIGID MATERIAL AND HAVING AN INNER DIAMETER SUBSTANTIALLY EQUAL TO THE OUTER DIAMETER OF THE TRAVELING-WAVE TUBE, PLUS CLEARANCE TOLERANCES, AND HAVING AN OUTER DIAMETER TO PERMIT ITS DISPOSITION WITHIN SAID FOCUSING MAGNET, SAID HOLLOW TUBULAR BODY MEMBER BEING FURTHER FORMED TO DEFINE A SPIRAL, STRAND RECEIVING CHANNEL IN THE OUTER CYLINDRICAL SURFACE THEREOF, SAID CHANNEL HAVING A PREDETERMINED DEPTH AND WIDTH AND BEING OF RELATIVELY CLOSE PITCH COMPARED TO SAID INNER DIAMETER OF SAID TUBULAR BODY, AND MAGNETIC STRAND MATERIAL HAVING A SUBSTANTIALLY CONSTANT CROSS DIMENSION APPROXIMATELY EQUAL TO SAID PREDETERMINED WIDTH, SAID STRAND MATERIAL BEING DISPOSED CONTINUOUSLY AND EVENLY ALONG AND WITHIN SAID STRAND RECEIVING CHANNEL.