More than 99% of the energy produced by the electron stream in an X-ray tube is converted into which form?

In an X-ray tube, the primary function is to generate X-rays by directing a stream of high-energy electrons at a targeted metal anode, usually made of tungsten. While the goal is to produce X-rays, the vast majority—more than 99%—of the energy from the electron stream is actually converted into heat rather than useful X-ray radiation.

This is due to the physics of how X-rays are produced. When high-velocity electrons collide with the anode, kinetic energy is transferred. Although some of this energy is converted to X-rays through processes like Bremsstrahlung and characteristic radiation, the majority results in heat due to inelastic collisions within the material of the anode. This heat buildup is significant and requires efficient cooling systems in the X-ray tubes to prevent damage.

To summarize, while X-rays are the intended output, the overwhelming conversion of energy into heat highlights the inefficiency of the process, making heat the primary byproduct in X-ray generation.