what is white x rays

X-rays are generated when matter is irradiated by a beam of high-energy charged particles such as electrons. In the laboratory, a filament is heated to produce electrons which are then accelerated in vacuum by a high electric field in the range 20-60 kV towards a metal target, which being positive is called the anode. The corresponding electric current is in the range 5-100 mA. The process is extremely inefficient with 99% of the energy of the beam being dissipated as heat in the target.