X=ray tube with separately switched heaters and screen - has aperture split by conducting strip and screen potential localising target area

摘要

An X-ray tube has two parallel heating elements which can be switched on separately. There is a screen between the anode and the cathode with an aperture to pass the electrons emanating from the cathode. The screen is connected to a potential during the operation approx. halfway between the anode and the cathode potential. The aperture is divided by an electrically-conducting strip (16). The strip is at the same potential as the screen (15). Its cross-section and location is such that the electrons emitted from the heating elements (35, 36) impinge on the anode in approx. the same area. The metallic piston of the tube is earthed, as is the screen and the strip.