JASRI/SPring-8, Hyogo-ken
In recent years ultimate storage ring has been studied aiming at ultra-small emittances and ultra-bright synchrotron radiation. Z. Hung et al.* studied an FEL in the EUV and soft x-ray regions in one of such rings as PEPX 4.5 GeV storage ring and showed that the three orders of magnitude improvement in the average brightness is possible at these radiation wavelengths. We studied an ultimate storage ring that has 0.034 nm-rad natural emittance and 5.4 MeV energy spread at 6 GeV**. The normalized emittance is 0.2 μm-rad with full coupling and the relative energy spread is 0.089 %. As smaller beam emittances and higher beam energy have possibilities of shorter wavelength FELs, we studied the feasibility of high-gain FELs in the range of x-ray regions as well as soft x-ray regions. In this paper we present the results of analysis and simulation of high-gain FEL in the ultimate storage ring.
*Z. Hung, et al., Nucl. Instr. Meth. A 593 (2008) 120.
** K. Tsumaki, N. Kumagai, Nucl. Instr. Meth. A 565 (2006) 394.
ELETTRA, Basovizza
Horizontal scraping, geometric and energy collimation of the Fermi@elettra electron beam has been investigated analytically and with the elegant particle tracking code. Beam scraping in the first magnetic bunch length compressor has been characterized in terms of reduction of the transverse emittance and variation of the energy chirp induced by the succeeding linac longitudinal wake field. The locations of the geometric and energy collimators have been identified in the machine lattice. A novel definition of collimation efficiency is proposed that allowed us to identify a configuration of the collimation system that is a compromise between the collimation performance, optics design and available space.