GB1388169A - Electron accelerator with control yoke - Google Patents

Abstract

1388169 Electron beam irradiation apparatus FORD MOTOR CO Ltd 9 Nov 1972 [15 Nov 1971] 51719/72 Heading H1D An electron accelerator for irradiating a target with an electron beam includes a vacuum chamber having rectangular electron permeable window 30, cathode 34, scanning means 36, 38, and control yoke 40 adjacent the window for deflecting the electron beam from divergent paths between the scanning means and control yoke into parallel paths 48, the yoke comprising first and second bars (50) (52) of magnetic material extending parallel to and on opposite sides of the window (also Figs. 4 and 7, not shown); with coils (58), (60) wound helically on each bar, the flux density varying along the window length to produce the parallel beams. Bars (50), (52), (e.g. of Fe), and coils (58), (60) are preferably rectangular cross-section, and spacers (54), (56) are non magnetic. The coils may be series connected and formed from one strand of wire or may be in parallel-series, and may be grouped or separately excited. Coil spacing may be uniform or non-uniform. Fig. 7 (not shown), illustrates a yoke to bend the beam in one angular direction only such as when the beam is to be unaffected for part of its scan and may be used with a curved or other complex shaped target. The yoke includes four bars (68), (70), (72), (74) and low reluctance connecting members (80), (82), (84). Coils (86) may be series or otherwise connected. Fig. 8 (not shown), has coils A, B, C each of progressively less turns, the flux being as in Fig. 9 (not shown). Figs. 4 to 6 (not shown) indicate other flux details. Envelope 14 is rectangular cross-section with ribs 16, while ribs 26 support Al window 30. Chamber parts are non-magnetic, e.g. stainless steel.