Materials Processing R&D with a Free Electron Laser
A unique light source to explore and develop laser-based processes may be based on a free electron laser driven by an energy-recovering linac. It can address much of the vast "white space" between the output wavelengths of conventional fixed-frequency lasers. The greatest success of conventional lasers is in delivering great energy intensity for ever-shorter pulse duration with increasing average power. They serve as sources of spatio-temporally dense electronic excitation, which can be converted to heat, especially in metals. In contrast, the inherent tunability of the FEL provides opportunity for channeling energy into specific vibrational pathways in a material to achieve desired effects. Organic materials offer a significant example, attracting as they do growing attention for next-generation photonics and electronics, with some applications already commercialized. Present fabrication techniques based on solvents or evaporation set limits on materials selection. Tuning the FEL to an IR absorption band, on the other hand, offers a path to molecule-selective energy deposition, enabling pulsed laser deposition, processing, and analysis of otherwise intractable materials. The UV FEL now coming into operation at JLab will offer further opportunities, as it will be able to drive electronic transition directly as well as the vibrational transitions accessible with the IR FEL. Authored by Jefferson Science Associates LLC under U.S.DOE Contract No. DE-AC05-06OR23177