Describe the function of the rotor and stator in a rotating-anode X-ray tube.

• A. Stator creates a rotating magnetic field to spin the rotor; the rotor drives the anode at high speed, enabling heat distribution and higher exposure capabilities.
• B. Rotor drives the filament to emit electrons.
• C. Stator cools insulating oil.
• D. They produce electrons.

Answer: (A)

In a rotating-anode X-ray tube, the rotor and stator form the drive system for the anode, which is essential for handling the intense heat produced during exposure. The stator is an electromagnet wrapped around the tube housing. When AC current flows through the stator windings, it creates a rotating magnetic field. This rotating field induces current in the rotor, which is a shaft with a laminated disk assembly connected to the anode.

The induced torque from the rotating magnetic field spins the rotor at very high speeds. That rotation is what drives the anode itself to high RPM. Spinning the anode distributes the heat over a larger surface area, preventing overheating and allowing higher exposure settings without damaging the tube.

Electrons are produced at the filament by heating it (thermionic emission) and are then accelerated toward the anode; the rotor and stator aren’t responsible for generating electrons. The stator’s job isn’t to cool insulating oil, and the components don’t create electrons themselves.