Oriented barium ferrite straight-field focusing structure

An oriented barium ferrite straight-field structure for focusing the electron beam of a klystron has been designed and successfully manufactured. The structure is a hollow tapered hexagon, circumscribed about a -inch outside diameter and -inch inside diameter. The overall height, including pole pieces, is inches. The peak axial field strength, before field shaping, is 1000 gauss, and transverse fields are held to 1 percent or less of the shaped axial field. We believe it is the first time a structure of this kind has been successfully made in hard ferrite. The method of construction is economical and can be utilized to produce parts having an infinite variety of physical dimensions, as well as differing field strengths. The permanent-magnet portion is composed of a number of blocks which could be made from larger magnets, previously rejected for physical resaons. This eliminates the necessity for prohibitively expensive special dies. It also provides a commercial use for magnets that would otherwise be scrap. The magnet design calculation is a modification of the technique published by Dr. M. Glass of Bell Telephone Laboratories. Consideration is given to temperature effects. Field shaping is attained by use of mild-steel auxiliary parts.