What is the side of the x-ray tube that has a negative charge called?

The side of the x-ray tube that has a negative charge is referred to as the cathode. The cathode is responsible for emitting electrons when heated, which is a critical step in the production of x-rays. It comprises two main components: the filament and the focusing cup. The filament, when energized, heats up and produces a cloud of electrons around it due to thermionic emission. The focusing cup is designed to direct these electrons toward the anode, where they will collide to produce x-rays.

Understanding the role of the cathode is vital in the context of x-ray production as it is essential for creating the high-energy electrons that ultimately result in x-ray generation when they interact with the anode. The functioning of the cathode is fundamental to the design and operation of x-ray tubes used in medical imaging.