Realization of a multi-turn energy recovery accelerator

Conventional electron linear accelerators are essential research tools but limited in providing high beam currents. Energy recovery technology enables high beam currents with reasonable and sustainable power supply requirements by recycling the electrons’ kinetic energy. Independently, higher beam energies can be achieved if electrons are accelerated multiple times in a linear accelerator. The combination of both techniques results in a multi-turn energy recovery linear accelerator, which is capable of providing high beam power. Here we report the demonstration of efficient energy recycling in multi-turn operation where we saved up to 87% of the consumed beam power in the main linear accelerator of the superconducting Darmstadt electron linear accelerator (S-DALINAC). In this setting, the cumulative phase slippage effect, caused by the different speeds of the electrons per main linear accelerator pass and the resulting different interactions with the alternating electric field, cannot be neglected and was compensated. Our proof-of-principle demonstration shows how multi-turn energy recovery linear accelerators can outperform conventional machines due to the potential for considerable power saving while providing higher beam power. By combining energy recovery technology and a multi-turn accelerating scheme in a linear accelerator, high-power beams can be achieved with considerably reduced energy consumption.