"Simplified schematic of a rotating anode X-ray tube envelope and housing. The rotating anode (A), spins via the rotor (R) and its bearings, creating a focal area of X-ray production around the anode target (T). The cathode (C), is shown with the filament circuit in green. All of these components are contained within the evacuated tube envelope (E). Just outside of the envelope is the stator (S), which induces rotation of the rotor. The tube envelope is surrounded in a dielectric cooling oil (O), with an expansion bellows (B) typically connected to a regulator switch, preventing over-expansion of the heated oil. X-ray beam leaves through the tube window (W), typically Aluminum or Beryllium while the rest of the housing will be lead or copper to attenuate stray X-rays."