In new research published in Nature Photonics (see front cover image above), a collaborative team of academics based at the Cockcroft Institute, including researchers from the ASTeC Femtosecond Lasers and Timing (FLT) Group have developed a unique solution using lasers to generate intense terahertz frequency pulses of light.
Terahertz (THz) is a region of the electromagnetic spectrum between infrared (used in TV remotes) and microwave (used in microwave ovens). Intense sources of terahertz radiation can be created by exciting a nonlinear crystal with a high-power femtosecond laser. Laser-driven sources greater than 1 GV/m are now possible, which is more than an order of magnitude larger than capable in a 'traditional' RF accelerating cavity. This new technology allows particles to be excited to higher energies over shorter distances, therefore reducing both the footprint and cost of a particle accelerator facility.
Professor Steven Jamison of Lancaster University who jointly leads the programme, explained: “The controlled acceleration of relativistic beams with terahertz frequency laser-like pulses is a milestone in development of a new approach to particle accelerators. In using electromagnetic frequencies over one hundred times higher than in conventional particle accelerators, a revolutionary advance in the control of the particle beams at femtosecond time scales becomes possible."
This research was part of an ongoing user access programme at CLARA accelerator at STFC Daresbury Laboratory and is a successful example of how the accelerator can generate impact for both UK and international collaborators. CLARA offers unique capability, providing access to FEL-quality electron beam combined with synchronized, high energy laser light.
Experiments are currently operated at 35 MeV in CLARA Beam Area 1. In the future, CLARA will be upgraded to 250 MeV, and Beam Area 1 will be replaced with a new specialized user beam line titled FEBE (Full Energy Beam Exploitation). Funding for a new high energy laser system for FEBE is being pursued, which would allow CLARA to continue to support world-leading research in novel means of particle acceleration.