Free-Electron Laser Gets a Boost from DoD

William and Mary physicists, applied scientists to benefit from an energy increase at JLab

The Thomas Jefferson Laboratory's Free Electron Laser will soon get a big boost in energy thanks to a grant from the Department of Defense in response to a proposal by Michael Kelley, professor of applied sciences. Under the DoD Defense University Research Instrumentation Program (DURIP), Kelley and colleagues Gunter Luepke, assistant professor of applied sciences, and Anne Reilly and Bill Cooke of the physics department, will be able to continue research that requires more energy from the Free Electron Laser (FEL) than is currently available. The grant, funded through the Office of Naval Research, will provide more than $466,000 to boost the FEL's functions.

The DoD grant provides funds to build a "pulse stacker" in which the energy of the FEL pulses will be increased by at least two orders of magnitude. The "pulse stacker" will be developed by William and Mary students in Luepke's new laser lab in Small Hall.

Cooke's research involves AMO studies, that is, the fundamentals of the response to atoms and molecules to light. "The boosted energy should be sufficient for the laser to accelerate an electron as if it were inside a black hole," he said. "Theories predict that these exotic conditions will produce Hawking/Unruh radiation, although this has not been observed anywhere."

Reilly works on pulsed laser deposition. This is a procedure that requires pulses of laser light to eject material having the exact original composition from a target, depositing the ejected material as a thin film of the same composition. Thin films are widely used in microelectronics and information storage applications.

Luepke will use the added energy boost in the FEL to explore the interaction of intense laser light with matter including damage to optics. Kelley's research, laser micromachining, will also benefit from the DURIP grant. Laser micromachining uses pulses of laser light to drill holes that are too small, have a special shape or are in difficult materials that cannot be done by conventional means.

"One example," Kelley said, "is a project on fuel injector orifices we are doing with Siemens; another is ablation of polymers." By tuning the FEL to just the right wavelength, he explained, the molecules composing the polymer can be cut in a chemically-selective way so that molecular organic thin films can be deposited.

"All of these applications and those of researchers elsewhere," Kelley said, "need more energy in each individual pulse from the FEL, more separation between pulses and the opportunity to change the length of the individual pulses. While this can be done by modifying the FEL itself, such an undertaking is costly and requires much prior research and development. Instead, the facilities funded by this proposal will accomplish most of these goals."

The FEL's energy boost will take the beam just as it comes from the free electron laser — the 'native beam' — and transform it to achieve all of the scientists. objectives. While it may not be as powerful and convenient as creating such a flexible FEL from scratch, Kelley said, "perhaps we'll learn that we can do all the science we need using this downstream beam conditioning equipment. That way, we may avoid the investment of time and funds in making a super-FEL."

The DURIP awards support the purchase of state-of-the-art equipment that augments current capabilities or develops new university capabilities to perform cutting edge defense research.