Patent ID: 8582722

Claim:
A rotary anode X-ray tube, comprising: a stationary shaft that has a large-diameter portion provided in a portion of the stationary shaft and is provided with a flow passage through which a cooling fluid flows, the large diameter portion having a larger diameter than a diameter of the stationary shaft; a cooling bath that is provided by thinning the wall thickness of the large-diameter portion to increase the flow passage diameter of a portion of the flow passage and the large-diameter portion located above a radial bearing; a rotary cylinder that covers an area of the stationary shaft including the large-diameter portion via a liquid metal and is rotatably supported to the stationary shaft; a target having a hollow circular plate shape that is provided on an outer circumferential surface of the rotary cylinder; a cathode that is disposed to face the target; and a vacuum enclosure that stores the stationary shaft, the rotary cylinder, the target, and the cathode and supports the stationary shaft, wherein the cooling bath has a columnar portion that is formed in a portion of the stationary shaft, in a state where the stationary shaft and a central axis are aligned, the large-diameter portion is composed of a cylindrical small-thickness portion provided to have a constant gap between the columnar portion and the small-thickness portion, and radial grooves that connect the gap between the columnar portion and the small-thickness portion and the flow passage of the stationary shaft other than the small-thickness portion are provided in both sides of the columnar portion.