What is an X-ray tube?
In this article:
- An X-ray tube is a vacuum-sealed device that generates X-rays by accelerating electrons from a heated cathode to a metal anode, where their sudden deceleration produces radiation.
- The core components include a cathode, anode, and glass or ceramic envelope, all housed in an ultra-high vacuum to ensure efficient electron flow and radiation generation.
- X-ray production depends on tube voltage (kV), which controls the energy and penetrating power of the emitted X-rays, critical for industrial radiography and non-destructive testing (NDT).
- The focusing cup shapes the electron beam, directing it precisely onto the anode target to optimize X-ray output and image resolution.
- Understanding X-ray tube design and function is essential for selecting the right equipment and settings in applications ranging from material inspection to medical imaging.
The X-ray tube, see figure 1-4, consists ofconsists of a glass (or ceramic) envelope containing a positive electrode (the anode) and a negative electrode (the cathode) evacuated to an ultra high vacuum [10 - 9 hPa (hectoPascal)]. The cathode comprises a filament that generates electrons. Under the effect of the electrical tension set up between the anode and the cathode (the tube voltage) the electrons from the cathode are attracted to the anode, which accelerates their speed.
This stream of electrons is concentrated into a beam by a “cylinder” or “focusing cup”. When the accelerated electrons collide with a target on the anode, part of their energy is
converted to X-radiation, know as X-rays.
What is the relationship between tube voltage and tube current?
