NOVOSIBIRSK FREE ELECTRON LASER FACILITY:TWO-ORBIT ERL WITH TWO FELS

Novosibirsk ERL has rather complicated magnetic system. One orbit for 11-MeV energy with terahertz FEL lies in vertical plane. Other four orbits lie in the horizontal plane. The beam is directed to these orbits by switching on of two round magnets. In this case electrons pass four times through accelerating RF cavities, obtaining 40-MeV energy. Then, (at fourth orbit) the beam is used in FEL, and then is decelerated four times. At the second orbit (20 MeV) we have bypass with third FEL. When magnets of bypass are switched on, the beam passes through this FEL. The length of bypass is chosen to provide the delay, which necessary to have deceleration instead of acceleration at the third passage through accelerating cavities. Last year two of four horizontal orbits are assembled and commissioned. The electron beam was accelerated twice and then decelerated down to low injection energy. First multi-orbit ERL operation was demonstrated successfully. In 2009 the first lasing at the second FEL, installed on the bypass of the second track, was achieved. The wavelength tunability range lays near 50 micron. Energy recovery of a high energy spread used electron beam was optimized. Third and fourth orbit assembly is in progress.