In a proton source based on cyclotron resonance, microwaves are used to strip electrons from hydrogen atoms. What remains are the hydrogen atomic nuclei, each consisting of only one proton. These protons leave the source with a potential of 60 kilovolts and are then subjected to a further voltage of 810 kilovolts in an accelerator tube. Both voltages are supplied by a Cockcroft-Walton accelerator. With a total of 870 kilovolts, the protons are accelerated to a speed of 46 million km/h or 4 percent of the speed of light. The protons are then fed into the Injector-2.