FLASHForward: high-quality, high-repetition-rate plasma-wakefield research

Plasma-wakefield acceleration (PWFA) exploits the enormous electric fields experienced at atomic scales by exciting coherent interactions in a gas of quasi-free electrons, otherwise known as a plasma. In principle such fields can attain values several orders of magnitude greater than attainable with even the most sophisticated and performant metallic accelerating cavities, whose surfaces at some point will break down as the electric-field gradient increases. The much higher gradients of PWFA could either greatly reduce the size and therefore the cost of energy-frontier particle accelerators, and/or attain much higher energies for the same cost.

The FLASHForward experimental facility located at DESY (Hamburg, Germany) is a high-performance test bed for precision PWFA research. Initial acceleration is carried out by the FLASH free-electron-laser superconducting radio-frequency cavities, providing high-quality, low-emittance, GeV-level electron bunches to the FLASHForward beamline for experimentation. The project aims to utilise these high-quality beams to address the outstanding challenges facing the field; namely the demonstration of highly efficient, quality-preserving acceleration of electrons at repetition rates compatible with the needs of current and future high-energy-physics and photon-science users.

This seminar will motivate the field, detail the current status of the FLASHForward facility, describe recent experimental highlights—including the preservation of longitudinal beam quality, the mapping of plasma-wakefield structures with femtosecond-level precision, and the quantification of the repetition-rate upper limit of plasma-wakefield schemes as defined by the fundamental physics process of ion motion—as well as outline plans for the future of the facility.