What is the area of the tungsten target called where high speed electrons strike the surface?

The area of the tungsten target where high-speed electrons strike the surface is referred to as the actual focal spot. This is where the interaction between the electrons emitted from the cathode and the tungsten target occurs, leading to the production of X-rays. The actual focal spot is a critical component in radiographic imaging because it determines both the quality and intensity of the X-ray beam produced.

In this context, the actual focal spot is associated with the precise area on the target that is affected by the electron bombardment. The size and characteristics of the actual focal spot can influence image resolution and the heat generated in the target, which is essential for the efficient operation of the X-ray tube.

Other terms, such as effective focal spot, are related but describe different aspects of the X-ray system. The effective focal spot refers to the focal spot's projected area as viewed from the image receptor, which can be influenced by target angle and other factors. Filtration zone and thermal zone do not specifically denote the area where electrons strike, but rather relate to other aspects of X-ray production and management of heat dissipation.