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Properties of the new UCSB free-electron lasers

Two new far-infrared free-electron lasers (FELs) are operating in a newly constructed beam switchyard and are providing radiation to an adjoining users' facility. These have been constructed to the highest standards, resulting in substantially improved operating characteristics. For example, greatly improved electron beam recirculation now permits FEL operation to more closely match theoretical prediction and has extended operating pulse width and repetition rate. The design characteristics and operating properties of these lasers are discussed.