(19)
(11) EP 0 991 106 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
03.05.2000 Bulletin 2000/18

(43) Date of publication A2:
05.04.2000 Bulletin 2000/14

(21) Application number: 99123769.4

(22) Date of filing: 21.11.1991
(51) International Patent Classification (IPC)7: H01J 35/16, H01J 35/04
(84) Designated Contracting States:
DE FR GB

(30) Priority: 21.11.1990 US 616464

(62) Application number of the earlier application in accordance with Art. 76 EPC:
91310751.2 / 0491471

(71) Applicant: VARIAN ASSOCIATES, INC.
Palo Alto, California 94304 (US)

(72) Inventors:
  • Richardson, John E.
    Salt Lake City, Utah 84121 (US)
  • Boye, James E.
    Salt Lake City, Utah 84103 (US)
  • Koller, Thomas J.
    Salt Lake City, Utah 84121 (US)

(74) Representative: Foster, Mark Charles 
Edward Evans & Co., Clifford's Inn, Fetter Lane
London EC4A 1BX
London EC4A 1BX (GB)

   


(54) High power X-Ray tube


(57) A high power x-ray generating tube (2) for reducing the effects of excessive heating of the window (16) through which the x-rays (16) are transmitted. The x-ray generating tube consists of a metal center section (6) having a stationary cathode (8) and a rotating anode (10). Various embodiments are employed for deflecting secondary electrons back scattered from the anode away from the window (16) to avoid overheating of the window. In particular the invention is characterised in that the window (16) includes insulating means for providing a build-up of negative charge on the inner surface of the window to repel secondary electrons (20). A grounded anode simplifies the mechanisms required to prevent overheating.






Search report