GB361179A - Improvements in or relating to x-ray tubes - Google Patents

Abstract

361,179. Rontgen-ray tubes. WESTINGHOUSE LAMP CO., Bloomfield, New Jersey; U.S.A.-(Assignees of Slack, C. M. ; 33, Berkeley Place, Bloomfield, New Jersey, U.S.A.) Jan. 9, 1931, No. 826. Convention date, Jan. 9, 1930. [Class 39 (i).] Soft X-rays are produced by a tube with a glass envelope surrounding the source of the rays and having a vitreous window of a thickness between À00004 and À002 inches shaped to withstand atmospheric pressure. The window is homogeneously united with the envelope and both may be of lime glass, material known under the Registered Trade Mark " Pyrex," or other glass resistant to moisture in the air. A dome-shaped window 14, Fig. 1, may be produced by suction after softening the end of the envelope. Low voltages of the order of 6 kilovolts are used to produce X-rays of wavelengths of 2-8 Angstrom units : rays of greater wavelength can be produced. Details of the penetration of windows of various thicknesses by rays of various wavelengths are given. The ray source may be close to the window to produce a wide angle of emergent rays. To shield the window from electron emission, the cathode supports 10, Fig. 1, are offset and the incandescent tungsten or tantalum coil 8 is set inside a focusing device 9. The anticathode is a plate 16 of tungsten, thorium, &c. bonded by a disc 17 of tantalum, molybdenum or tungsten to a copper body 3 which may be provided with a heat radiator or water cooler. In a tube for treatment of the mouth and throat, Fig. 2, the cathode is a coil 27 in an insulating sleeve 25 in a metal cap 23 between the anode 31 and the window 36, the coil 27 being of diameter greater than the aperture 24 in the cap 23. In a tube for treating the nose and ear, a small window is formed at the end of a narrow glass tube sealed to the end of the envelope. The electrodes are freed from gas by heating to red heat before assembly and by heating after assembly by electronic bombardment and eddy currents. A filling of neon at 1-10 microns may be used. Prior tubes for producing soft X-ravs with windows of aluminium À00015 inches thick and of Lindemann glass coated with shellac or lacquer, are referred to.