Optics of beam transport in the NSLS uv-FEL

The NSLS-FEL is designed as a single pass FEL to generate radiation 1 mJ per pulse (10 psec) in 10-4 bandwidth, with continuously tunable wavelength in the range 100--300 nm. A superconducting, recirculating linac provides electron beams of energy 20 MeV to 260 MeV at 4π mm mrad normalized rms emittance with less than 0.1% momentum spread and 2 mm rms bunch length. The optics in this machine is seriously restricted by the requirement to not degrade the electron beam quality. We present a lattice design for the transport lines to be used in beam injection, linac focussing and recirculations. These beam lines are tuned to be linearly achromatic and isochronous, to avoid beam breakup in the cavities, and to minimize second order distortions of the emittance. Special transport lines are designed that allow rapid switching of the electron beam to drive two different FEL wigglers. This provides the capability for up to four simultaneous, high power, independently energy tuned laser beam