GB460181A - Improvements in and relating to roentgen-ray tubes - Google Patents

Abstract

460,181. R÷ntgen-ray tubes. AJKAY, F. R., and BITTERA, J. May 20, 1935, No. 14743. Convention date, May 19, 1934. [Class 39 (i)] A R÷ntgen-ray tube is provided with means for producing a magnetic field in such a manner that the path of the electron stream can be moved when desired laterally and relatively to the anticathode to change the position of the focal spot or portion of the anticathode on which the stream impinges. The focal spot can be changed before the surface of the anticathode becomes overheated or damaged. The magnetic means may be an uncored coil e surrounding the tube, or electromagnets or permanent magnets. The movement of the spot may be performed by adjusting the magnetic means in a suitable mounting, or by varying the direct current through a coil. The size of the focal spot can be varied at the same time. Specification 460,270 is referred to. The Specification as open to inspection under Sect. 91 comprises also the use of a curved anticathode c1, Fig. 3 (Cancelled), which is struck by electrons uniformly over its surface. R÷ntgen rays emitted nearly normally to the surface pass through an apertured diaphragm f situated at the centre of curvature. The cathode may be heated by induction, as described in Specification 460,270. A magnetic velocity selector may be employed in gas-filled tubes, so that electrons of only one velocity reach the anticathode. The anticathode may be rotated by the action of the electron stream, and, as described in Specification 460,271 a magnetic brake may be used to control the rotation. This subject-matter does not appear in the Specification as accepted.