Energy efficiency comes to the study of particle physics with a successful test of energy capture and reuse technology in a multi-turn particle accelerator. Researchers from Cornell University and U.S. Brookhaven National Laboratory (BNL) demonstrated particle beam reuse in the Cornell-BNL Energy Recovery Linear (ERL) Test Accelerator.

The novel eight-pass superconducting ERL accelerator captures and reuses the energy of previously accelerated Schematic of the Cornell-BNL ERL Test Accelerator. Source: BNLparticles. A beam makes eight instead of four passes through a superconducting radio frequency cavity, decelerating during the last four passes to enable energy capture and application for new particle acceleration. Energy efficiency is also attributed to the elimination of electric power requirements for system operation, as fixed-field alternating linear gradient beamline is composed of permanent magnets. The beamline directs particles back to the superconducting radio frequency cavity in a design that does not need multiple accelerator rings to accommodate beams at different energies.

The first demonstration of the return loop technology used an electron beam at 6 million electron volts (MeV) to bring particles to 42, 78, 114 and 150 MeV in four passes through the ERL. Four additional passes through the superconducting cavities decelerated particles to their original 6 MeV energy at the same position as the starting beam. The initial test achieved full electron energy recovery and energized the cavities sufficiently to accelerate the next batch of particles.

The energy reuse method results in brighter beams, which previously depended on a more energy-intensive process. The researchers envision applications in medical isotope production, micro-chip production and other fields.