The voltage requirement for the operation of a high-voltage electron gun in particle accelerators can vary widely depending on the specific design, application, and desired electron beam energy. However, in general, high-voltage electron guns typically require voltages in the range of tens of kilovolts (kV) to several hundred kilovolts.
For example, electron guns used in linear accelerators (linacs) for medical applications or industrial processes might operate at voltages between 100 kV and 10 MV (megavolts), depending on the desired energy of the accelerated electrons and the specific purpose of the accelerator. In research particle accelerators, where higher energies are often required to probe the fundamental properties of matter, electron guns might operate at even higher voltages, sometimes reaching several tens of megavolts.
The specific voltage requirement depends on the desired final energy of the accelerated electrons, the accelerator's overall design, the acceleration method (such as radiofrequency cavities), and the desired application. It's important to note that higher voltages also bring challenges related to electrical breakdown, insulation, and safety, which need to be carefully considered in the design and operation of high-voltage electron guns and accelerators.