CURRENT STATUS OF THE SUPERCONDUCTING RF LINAC DRIVER FOR THE JAERI FREE-ELECTRON LASER

A prototype for a quasi-cw, and 1 kW high-average power free electron laser (FEL) driven by a 15 MeV superconducting rf linac has been devel oped, and constructed at Tokai, JAERI. Cryogenic stand-by loss (<3.5 W at 4.2 K) and accelerating fields' performances (E(acc) > 7 MV/m and Q similar to 2 X 10(+9)) of four JAERI superconducting accelerator mod ules have been successfully demonstrated. Beam test and commissioning of the JAERI superconducting rf linac have been successfully performed to get electron beams ranging from 10 to 23 MeV and the fully transmi tted of similar to 16 A peak current around 17 MeV. The measured energ y resolution of a pre-accelerated beam is about 3% of FWHM, and that o f a fully-accelerated beam about 0.8% or less. The measured micropulse width is adjustable in the range from 10 to 60 ps. FEL opticals and b eam transport elements around the undulator are now under commissionin g. Spontaneous emissions in the wavelength of 20 to 80 mu m or longer have been observed by using the Ge(Cu) and other detectors, a home-mad e fast current amplifier, and a 24 m long light transporting system.