ASNT Industrial Radiography Radiation Safety Practice Test

The cathode in an X-ray tube serves as what kind of source?

1. Proton source

2. Neutron source

3. Electron source

4. X-ray source

The correct answer is: Electron source

The cathode in an X-ray tube serves as an electron source. In the operation of an X-ray tube, the cathode is responsible for generating electrons through a process called thermionic emission. When the filament within the cathode is heated, it emits electrons due to the increased thermal energy. These electrons are then accelerated toward the anode, where they collide with the target material and produce X-rays through a process known as bremsstrahlung and characteristic radiation. Understanding this role is crucial for comprehending how X-ray machines function. The ability of the cathode to emit electrons effectively is foundational to the X-ray production process, as it sets in motion the subsequent steps that lead to the generation of X-ray photons, which are then used for imaging purposes in radiography. This highlights the importance of the cathode as an essential component in the production of X-rays for industrial and medical applications.