GB1435526A - Electron bearm deflection tube - Google Patents

Abstract

1435526 Electron beam focusing and deflecting systems; X-ray tubes TEKTRONIX Inc 18 July 1973 [4 Aug 1972] 34143/73 Heading H1D An electron tube comprises cathode 40, an anode with beam limiting aperture 44, target 50 (e.g. light sensitive or silicon oxide storage), twisted and interleaved deflection electrodes 48 (also Figs. 3, 4 and 5, not shown) for generating a twisted electric field extending perpendicular to the tube axis at an orientation varying continuously and uniformly along the axis to provide two co-ordinate beam deflection, solenoid 25 producing a uniform oxide field proportional to the magnetic dwell angle which angle differs from the angle of twist of the E field by integer multiples of 2# radians, the B and E fields producing a helical motion of the beam so that the beam impinges orthogonally on the target and is scanned thereacross. The plane of deflection of the beam is also prevented from rotating away from the initial E field direction. Fig. 2 also includes grid 41, accelerator 42, barrel 45 providing field free drift space or prefocus lens according to potentials, deflection shield 46, and target mesh 49. Detailed theory is given for deflection and focusing operation for zero shading (i.e. right angle incidence on target), requiring # m =# e t2 n# where # m and # e are the magnetic dwell and electric twist angles. Characteristics are produced in Figs. 7-14 (not shown). Solenoid 25 may extend past the target to reduce fringing fields. Deflection 48 may be produced photographically. Applications include high beam intensity microspot tubes scan converters, monochrome or colour TV projection apparatus, vidicon or image orthicon tubes, X-ray tubes or high power focused beam tubes for electron machining, welding or contour drilling.