A Highly Flexible Bunch Compressor for the APS LEUTL FEL

TL;DR

This paper presents a novel, highly adaptable bunch compressor design for the APS LEUTL FEL aimed at increasing peak current and controlling emittance growth, with detailed features and expected performance analysis.

Contribution

It introduces a flexible bunch compressor with variable R56 and movable dipoles, enhancing control over emittance growth for FEL applications.

Findings

Design achieves peak current of 600 A or more.

Variable R56 allows emittance growth control.

Chicane features adjustable symmetry and diagnostics.

Abstract

The LEUTL FEL at the APS has achieved gain at 530 nm with peak beam current \~100 A. In an effort to push to 120 nm and beyond, we have designed and are commissioning a bunch compressor to increase the peak current to 600 A or more. The bunch compressor uses a four-dipole chicane at an energy of 100 to 210 MeV. To provide options for control of emittance growth due to coherent synchrotron radiation (CSR), the chicane has variable R56. The central pair of dipoles is movable, accommodating variable R56 with less concern about emittance dilution from nonuniformity of the dipole field. The symmetry of the chicane is also variable via longitudinal motion of the final dipole, which is predicted to have an effect on emittance growth. Following the chicane, a three-screen emittance measurement system should permit resolution of the difference in emittance growth between various chicane configurations. A vertical bending magnet analysis line is present to permit imaging of correlations between transverse and energy coordinates. This paper reviews the features and expected performance of the chicane. A companion paper discusses the physics design in detail. Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.