GB1361771A - Apparatus for heating material by means of a electron beam in a vacuum - Google Patents

Abstract

1361771 Electron beam furnaces LEYBOLDHERAEUS-VERWALTUNG GmbH 6 Feb 1973 [15 Feb 1972] 5894/73 Heading H1D In an electron beam vaporizer the beam is deflected on to the target 2 through an angle of 90 degrees or more by a principal poleshoe system 8, 9 which produces a flux which decreases, in the plane of the beam path, from the inner to the outer edge of the beam, and on auxiliary poleshoe system 19, 20-disposed on that side of the cathode 24 remote from the targetwhich produces a flux which decreases from the outer to the inner edge of the beam. As shown, the target is a crucible 1 rotatable to introduce any one of cups 2 to 5 into the beam path; the poleshoes 8 and 9 have conical surfaces 10 and 11 to avoid rising vapour, and inclined faces 12 and 13 defining a V section giving the required change of flux across the beam; and the poleshoes 19 and 20 are connected by legs 16 and 17 to the main shoes 8 and 9, and have inclined ends 21 and 22 to give the desired flux change. Reference is made to an arrangement having a beam deflection angle of 270 degrees; to auxiliary poleshoe surfaces that are concave or convex, rather than plane, and which exhibit a wedge angle of between 60 degrees and 120 degrees, and preferably between 80 degrees and 100 degrees; and to the circulation of coolant through the hollow walls of the crucible. A dismountable cathode assembly is described, Fig. 3, in which the cathode legs are secured to contact plates 43 and 44, respectively, themselves secured together with interposed insulators 46 and 48 by screw 47, the assembly being removable by undoing screw 50, accurate repositioning with respect to the Wehrelt focusing cylinder 26 being facilitated by skirt 51 and projection 52.