x-ray tube, a large vacuum tube containing a tungsten filament cathode and an anode that often is a tungsten disk. When heated to incandescence, the cathode emits a cloud of electrons that produce x-rays when they strike the surface of the anode at high speed. The anode is designed to deflect the x-rays toward an object to be radiographed. X-ray tubes are produced in a variety of designs for different purposes. Low-kilovoltage x-ray tubes may contain anodes made of molybdenum rather than tungsten. Some anodes are stationary and others rotate at high speed. Because of the intense heat generated by x-ray production, the specific design usually includes devices to help dissipate the heat.
