CERN Accelerating science

Article
Title	Upgrade of the L-Band Linac at ISIR, Osaka University for a Far-Infrared FEL
Author(s)	Kato, Ryukou ; Isoyama, Goro ; Kashiwagi, Shigeru ; Suemine, Shoji ; Yamamoto, Tamotsu
Affiliation	(ISIR, Osaka)
Publication	2004
In:	26th International Free Electron Laser Conference and 11th FEL User Workshop 2004, Trieste, Italy, 29 Aug - 3 Sep 2004, pp.e-proc. TUPOS26
Subject category	Accelerators and Storage Rings
Abstract	We are developing the far-infrared free-electron laser (FEL) using the L-band electron linac at the Institute of Scientific and Industrial Research (ISIR), Osaka University. The first lasing of the FEL was obtained at wavelengths from 32 to 40 μm in 1994, and the wavelength region has been extended up to 150 μm. The linac was designed and constructed for producing the high-intensity single-bunch beam for pulse radiolysis, so that the filling time of the accelerating structure is 1.8 μs long and the maximum macropulse length of the electron beam is limited to 2 μs, though the duration of the RF pulse can be extended to 4 μs. As a result, the FEL could not reach power saturation because the number of amplification times was limited. Recently, the linac has been extensively remodeled to realize high operational stability and reproducibility for advanced studies in beam science and technology. Almost all the peripheral components are replaced with new ones. At this opportunity, the linac is also made suitable for FEL so that the macropule can be extended up to 6 μs in duration for power saturation of the FEL. The modification of the linac has been completed and commissioning is now in progress. In this paper, we will report performance and characteristics of the linac after modification.