High vacuum rotating anode X-ray tube

Claim 1

In a CT scanner, a high voltage high vacuum rotating anode X-ray tube comprising: (a) a andoe adapted for rotation about an axis therethrough, the anode having a rotor and a shaft extending therefrom; (b) a housing enclosing portions of said rotor and defining therewithin an evacuated region of high vacuum; (c) an electron gun fixedly mounted through said housing, said electron gun adapted and configured to emit a beam of electrons to be incident in said region on the rotor of said anode for generating X-rays; (d) fluid magnetic sealing means disposed about the shaft of said anode for fluidically sealing the high vacuum in said region while permittting rotation of said anode; (e) bearing means disposed about said shaft outside of said high vacuum region for transmitting rotary motion through said sealing means; (f) window means formed on said housing for permitting transmission of X-rays through said housing; and (g) an annular static seal disposed on said rotor within the high vacuum region; (h) wherein said magnetic sealing means comprises a pair of annular pole pieces separated by a plurality of magnets, said pole pieces fitted about the shaft of said anode, with vacuum sealing between said pole pieces and the shaft provided by a magnetic fluid and further comprising means for maintaining the pressure imtermediate the two pole pieces at a relatively low pressure of or below approximately 100 millibars.