Design of an X-ray FEL undulator

Journal Article · Sun Jun 01 04:00:00 EDT 1997 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.54426· OSTI ID:664853

Carr, R ^[1]

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1. Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Stanford, California94309 (United States)

An undulator designed to be used for an x-ray free electron laser has to meet a set of stringent requirements. With no optical cavity, an x-ray FEL operates in the single pass Self Amplified Spontaneous Emission (SASE) mode; an electron macropulse is microbunched by an undulator and the radiation it creates. The microbunched pulse emits spontaneous radiation and coherent FEL radiation, whose power may reach saturation in a sufficiently long and perfect undulator. The pulse must have low emittance and high current, and its trajectory in the undulator must keep the radiation and the pulse together with a very high degree of overlap. In this paper we use the case of the Linear Coherent Light Source (LCLS) x-ray free electron laser to illustrate design concepts for long free electron laser undulators. The LCLS is intended to create 1.5 {Angstrom} x-rays using an electron beam with 15 GeV energy, 1.5{pi} mm-mrad normalized emittance, 3400 A peak current, and 280 fsec FWHM bunch duration. According to our simulations, this 2{sigma}{sub r}=65mmrms diameter beam must overlap its radiation with a walkoff of no more than 5 {mu}m RMS per 11.7 meter field gain length for efficient gain. The energy spread of the beam is {sigma}{sub E}=0.0002E{sub e}. This places severe limitations on the magnetic field errors and on mechanical tolerances. In this paper we shall discuss how to meet these requirements. {copyright} {ital 1997 American Institute of Physics.}

• Research Organization: Stanford Linear Accelerator Center
• Sponsoring Organization: USDOE
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 664853
• Report Number(s): CONF-9706244--
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 413; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
COHERENT RADIATION
DESIGN
FREE ELECTRON LASERS
GAIN
OPERATION
PERMANENT MAGNETS
STABILITY
SYNCHROTRON RADIATION
X-RAY LASERS