A radiation emission device is provided. The radiation emission device may include a cathode configured to emit an electron beam and an anode configured to rotate on a shaft. The anode may be situated to receive the electron beam from the cathode. The radiation emission device may further include a rotor configured to drive the anode to rotate. The rotor may be mechanically connected to the shaft. The radiation emission device may further include a sleeve configured to support the shaft via at least one bearing. The cathode, the anode, and the rotor may be enclosed in an enclosure that is connected to the sleeve. At least a portion of the sleeve may reside outside the enclosure.