We report on experimental studies of an ultraviolet (UV) free-electron laser (FEL) oscillator driven by low-energy electrons from a radio-frequency linear accelerator. Previous UV FELs have been driven by 350-800-MeV electrons from storage rings. We verify the concept of driving an UV FEL with a low-energy, but high-current, low-emittance electron beam. This and other innovations allowed the FEL to lase at wavelengths from 369 to 380 nm using 45.9-45.2-MeV electrons, and to achieve a peak optical output power of 270 kW. The experimental results are in good agreement with simulations.
A tunable infrared free-electron laser comprised of a train of picosecond pulses was utilized to destroy the Freons CFCl 3 and CF 2 Cl 2 by multiple-photon dissociation. The experiments explored the effects of laser frequency, laser fluence, spectral bandwidth, frequency chirping, reactant partial pressure, and oxygen (or air) partial pressure. We determined the optimum laser frequencies for dissociation of both of the Freons and also showed that a broader spectral bandwidth laser enhances reaction. A strong reduction of dissociation fraction with increasing pressure made infrared photodissociation of Freons at near atmospheric pressure difficult. Improvement of the high-pressure photolysis would require a laser macropulse much shorter than the 2 µs used in these experiments.
LosAlamosNational Laboratory, an affirmative action/equal opportunity employer, isoperated bytheUniversity of California forthe U.S Department of Energy undercontract W-7405-ENG-36. Byacceptance ofthisarticle, thepublisher recognizes thattheUS. Government retains a nonexclusive, royalty.free licenseto publish orreproduce thepublished formofthiscontribution, ortoallow others todoso,forU.S,Government purposes, TheLosAlamosNational Laboratory requests thatthe publisher identify th=sarticle asworkperformed under the auspices ofthe U.S Department of Energy.
The LCIS Alirmos (rce-electron hser (FEL) facility has been greatly mudificd by [he rc$ncement of [h: thcrmio~ic eleclron gun nnd bunchers wilh n 1300 MHz RF photoinjec[or, Two more~ccelerntor ranks have been added to incremc lhc hcnm energy 1040 MeV. Preliminary studies at 15 McV hirvc dcmonsmued cxcellem beam quali[y with a normal ir.cd cmilhmce of 40 n mm.mrnd. The beam qusslity is now sufficient [n nllow hnrmoni~Insing in the visible. Al prcscnl wc arc beginning FEL cxperimcn[s nl a wavclcnglh near 3 pm. II] this pirpcr we rcpcrrt on the pcrformtrncc of our phominjcc[nr accclcri~(or.
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