CoreFree
X-ray Production and Target Interactions
Electrons hit the tungsten target: about 99% of their energy becomes heat, under 1% becomes x-rays.
How it works
Heating the filament boils off electrons by thermionic emission. The kVp accelerates these projectile electrons from cathode to anode, where they strike the tungsten target. Most of the time a projectile electron only excites outer-shell electrons of target atoms, which produces heat. About 99 percent of the electrons' energy becomes heat and less than 1 percent becomes x-rays. That is why tube heat limits matter.