GB1164268A - Improvements in or relating to Electron Beam Apparatus. - Google Patents

Abstract

1,164,268. Electron beam apparatus. AIR REDUCTION CO. Inc. 13 Dec., 1966, No. 55797/66. Heading H1D. Electron beam apparatus for treating material 24 comprises an air-tight enclosure 10 divided into chambers 12, 14 and 16 by barriers 18 and 20 with apertures 26 and 28 of the same size and shape as emitting surface 22 (preferably a Pierce type gun with a directly or indirectly heated cathode, Fig. 2 (not shown). A uniform magnetic field provided by ironcored coils 42, 46 or Helmholtz coils (60), (62) and (64) (Fig. 3, not shown) for instance, cause electrons from surface 22 to follow a helical path to the aperture 26 and between apertures 26 and 28, the distances between the apertures and the emitting surface being equal to an integral number of revolutions of the helical path. The apertures are preferably rectangular to promote molecular rather than viscous flow between the pressure graded chambers. The pressure difference on the opposite sides of each barrier may be in the ratio of between 10: 1 to 100: 1. The gun chamber may be evacuated to 0À6 or higher than 0À1 Á Hg. the transition chamber to 17 Á Hg. and the treating chamber to 100 Á Hg. Polepieces 38, 40 and 44 may be a ferromagnetic such as steel, or the barriers (18a) and (20a) (Fig. 3, not shown) may be of watercooled copper. To minimize contamination of chambers 12 and 14, target 24 may not be in alignment with the apertures, a transverse magnetic field effecting curvature of the electron beam after aperture 28. More than one gun 22 may be included with associated apertures and only two or more than three chambers may be provided. Reference is made to melting, annealing, cleaning and vapour-plating.