GB624030A - Improvements in or relating to rotary x-ray tubes - Google Patents

Abstract

624,030. X-ray tubes. PHILIPS LAMPS, Ltd. Jan. 23, 1947, No. 2154. Convention date, Dec. 31, 1943. [Class 39 (i)] A rotating X-ray tube has the electron beam directed in an oblique path to the target by a directing body which is held stationary in the proximity of the cathode, and which may be inside or outside the envelope. In Fig. 2, the cathode 3 is surrounded by two caps 13, 14 with oblique diaphragms containing apertures 29, 30 which direct the electrons in an oblique path to the anode 2, which may be hollow and liquid-cooled. The caps are attached by screws 15 to ferromagnetic poles 10, but mutually insulated by rings 16. Cap 13 revolves round ball-race 17 which also connects it electrically via bush 21 to supply wire 18. Similarly, cap 14 is connected via poles 10 and ball-race 19 to supply wire 20. A magnetic yoke 6 holds the poles 10 and the attached caps 13, 14 stationary, while the remainder of the system rotates. Caps 13, 14 may be given negative and positive potentials respectively, thus forming an electron lens controlling the spot size. A diaphragm whose front face is normal to the direction of the electron beam may be rotatably mounted on the anode, and connected to the directing body by means of an insulator. Fig. 1 (not shown) is a simpler modification with only one cap, which need not necessarily be at cathode potential. In Fig. 3 (not shown) the directing body is outside the envelope, and may be cylindrical or funnelshaped, with a wide longitudinal slit, the resulting asymmetrical field causing deviation of the electron path. German Specification 574,865 is referred to.