On 15 July in Newport News, Virginia, Jefferson Lab’s free-electron laser (FEL) produced infrared light at a wavelength of 3.1µm and 1.72 kW average power, thereby exceeding the kilowatt design goal. No FEL has previously exceeded 14 W.
The infrared Demo FEL is the first in a series of high-average-power, wavelength-tunable FELs being developed at Jefferson Lab for basic science, industrial applications and applied defence research. FEL development is a spinoff from the laboratory’s main mission of accelerator-based investigations into the quark structure of nuclei. The superconducting radiofrequency (SRF) electron accelerator at the heart of the FEL is derived from the technology of Jefferson Lab’s 6 GeV continuous-wave main machine.
In July’s record-setting laser operation, untapped electron-beam energy was recovered by recirculating the beam back through the driver accelerator for “deceleration.” The driver was operated at 4.4 mA and 48 MeV, approaching its maximum design power of 250 kW. Energy-recovery capability would contribute significantly to fully developed SRF-driven FELs’ cost-effectiveness.
Upcoming FEL user experiments include silicon characterization studies (by a group from Vanderbilt), laser photodeposition (Norfolk State), photoablation (William and Mary), polymer surface modification (DuPont) and metal surface modification (Armco/Virginia Power).
Crucial to Jefferson Lab’s ongoing FEL effort is the support of the US Department of Energy, the Office of Naval Research, the Commonwealth of Virginia and industry and university partners in the Laser Processing Consortium.