Electric discharge tubes

364,568. Discharge apparatus. SIEMENS-REINIGER-VEIFA GES. FœR MEDIZINISCHE TECHNIK, 58, Mohrenstrasse, Berlin. Oct. 2, 1930, No. 29543. Convention date, Oct. 24, 1929. [Class 39 (i).] High tension high vacuum discharge tubes such as X-ray, rectifying and cathode ray tubes and oscillation generators are protected against rupture by electric discharge b y t h e provision of a jacket space formed by an intermediate tube 6 at their most endangered parts, e.g. the discharge space, the tube 6 being attached to the main tube at the anode end 7 and d extending beyond the cathode 3 to form an open end flared so as to leave a small clearance with the wall of the tube. The jacket space is thus in communication with the discharge space through an opening of such position size and nature as to prevent the passage of electrons to the jacket space. In the application to X-ray tubes, a metal sheath may be arranged inside the tube 6 to surround the discharge space to protect the tube from bombardment. The outer tube 1 may be surrounded by a metal ring 10, Fig. 3, having a window 11 for the emission of X-rays and this ring may be secured to the supporting stand and earthed. In addition, the anode and cathode necks may be protected against undesired radiation by surrounding them with cylinders of insulating material mixed with heavy metal compounds and glazed. In place of these cylinders the inner tube 6 may be of lead glass having a gastight insulating window.