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An accelerator accelerates charged particles (ions) , here protons, by subjecting them repeatedly to momentary electrostatic fields. Repeatedly because there are technological limits to the increase in energy one can obtain in a single acceleration step. Two different types of accelerators exist: linear accelerators (linacs) and cyclotrons. A linac has successive cavities in which the phase of the applied radio frequency (RF) waves is steered in such a way as to add to the ever increasing particle energy. In a cyclotron, the trajectories of the charged particles are bent approximately to circles by a magnetic field forcing the ions to repeatedly pass the same of radiofrequency cavities placed inside a large magnet. Due to the increase of energy the radius of curvature of the ions is steadily increasing until they leave the magnet. |
Since particles tend to become "relativistic" (i.e. their mass becomes energy dependent) at the high energies required, special corrective measures are needed to keep the particles synchronized with the radiofrequency wave. The main challenging research topic for the accelerator as part of an ADS is the improvement of the beam reliability as an ADS is intended to be operated in a continuous way. This is one of the main reasons why a linac has been chosen as the accelerator type for MYRRHA.