Abstract: A rotating anode for x-ray generation uses a heat pipe principle with a heat pipe coolant located in a sealed chamber of a rotating portion of the anode. The rotating portion is positioned relative to a second portion so that relative rotation occurs between the two portions and so that a fluid path exists between the two portions through which an external cooling fluid may flow. The relative motion between the two portions provides a turbulent flow to the cooling fluid. The anode may also include cooling fins that extend into the sealed chamber. The sealed chamber may be under vacuum, and may be sealed by o-rings or by brazing. A closable fill port may be provided via which heat pipe coolant may be added. A balancing mass may be used to balance the anode in two dimensions.