Which material is most commonly used for targets in X-ray tubes?

The most commonly used material for targets in X-ray tubes is tungsten. This is because tungsten has several properties that make it particularly suitable for this application.

Firstly, tungsten has a high atomic number, which enhances the efficiency of X-ray production. When high-energy electrons collide with the tungsten target, more X-rays can be produced due to the higher probability of photoelectric effect and Compton scattering, which are the primary processes involved in X-ray generation.

Secondly, tungsten has an exceptionally high melting point of around 3,420 degrees Celsius (6,192 degrees Fahrenheit). This allows the target to withstand the intense heat generated during the electron bombardment without melting or deforming, which is crucial for maintaining the stability and integrity of the X-ray tube.

Additionally, tungsten has good thermal conductivity, which means it can effectively dissipate the heat generated during the X-ray production process. This property helps prolong the life of the X-ray tube by preventing overheating, which can lead to premature failure.

While other materials like copper, titanium, and aluminum have their uses in various applications, they do not offer the same combination of high atomic number, high melting point, and good thermal conductivity as tungsten, making tungsten the optimal choice for X-ray tube targets.