ICAP2015 - Table of Session: WEBJ (APS Emittance Upgrade and LCLS/LCLS-II X-ray Self-seeding)

Paper	Title	Page
WEBJI1	Simultaneous Simulation of Multi-particle and Multi-bunch Collective Effects for the Aps Ultra-low Emittance Upgrade	61
	M. Borland, T.G. Berenc, L. Emery, R.R. Lindberg ANL, Argonne, Ilinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Next-generation storage ring light sources promise dramatically lower emittance due to the use of multi-bend achromat (MBA) lattices. The strong magnets required for such lattices entail small magnet and vacuum bores, which increases concerns about collective instabilities. In this paper, we describe detailed simulations undertaken for the APS MBA lattice using the parallel version of ELEGANT. The simulations include short- and long-range geometric and resistive wakes, a beam-loaded main rf system including feedback, a passive harmonic bunch-lengthening cavity, higher-order cavity modes, and bunch-by-bunch feedback. Applications include insight into transients during filling, effects of missing bunches, evaluation of non-uniform fill patterns, and determination of feedback system requirements.
	Slides WEBJI1 [1.413 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-ICAP2015-WEBJI1
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WEBJI2	Soft X-ray Self-seeding at LCLS and LCLS-II: Simulation and Experiment
	G. Marcus SLAC, Menlo Park, California, USA
	X-ray free electron lasers (XFELs) have become essential tools for the investigation of dynamical systems as they have the ability to operate on the time and length scales natural to atomic and electronic motion in matter. The recent addition of soft X-ray self-seeding as an operational mode at LCLS allows for the production of narrow bandwidth FEL pulses, which is useful for a variety of advanced spectroscopic investigations. Recent experimental results, however, show the persistence of a small spectral ‘pedestal' that underpins the narrow amplified signal. Here, we report on potential sources of this pedestal that have been investigated using high-fidelity numerical particle simulations for two facilities: LCLS and LCLS-II. Furthermore, a new numerical method used to propagate the full three dimensional FEL pulse through the grating based monochromator will be presented. This method leverages a new theoretical model based on a modified Huygens-Fresnell integral that includes non-separable spatio-temporal couplings and temporal dispersive effects up to a quadratic phase.
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Paper

Title

Page

Simultaneous Simulation of Multi-particle and Multi-bunch Collective Effects for the Aps Ultra-low Emittance Upgrade

61

M. Borland, T.G. Berenc, L. Emery, R.R. Lindberg
ANL, Argonne, Ilinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Next-generation storage ring light sources promise dramatically lower emittance due to the use of multi-bend achromat (MBA) lattices. The strong magnets required for such lattices entail small magnet and vacuum bores, which increases concerns about collective instabilities. In this paper, we describe detailed simulations undertaken for the APS MBA lattice using the parallel version of ELEGANT. The simulations include short- and long-range geometric and resistive wakes, a beam-loaded main rf system including feedback, a passive harmonic bunch-lengthening cavity, higher-order cavity modes, and bunch-by-bunch feedback. Applications include insight into transients during filling, effects of missing bunches, evaluation of non-uniform fill patterns, and determination of feedback system requirements.

Slides WEBJI1 [1.413 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-ICAP2015-WEBJI1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEBJI2

Soft X-ray Self-seeding at LCLS and LCLS-II: Simulation and Experiment

G. Marcus
SLAC, Menlo Park, California, USA

X-ray free electron lasers (XFELs) have become essential tools for the investigation of dynamical systems as they have the ability to operate on the time and length scales natural to atomic and electronic motion in matter. The recent addition of soft X-ray self-seeding as an operational mode at LCLS allows for the production of narrow bandwidth FEL pulses, which is useful for a variety of advanced spectroscopic investigations. Recent experimental results, however, show the persistence of a small spectral ‘pedestal' that underpins the narrow amplified signal. Here, we report on potential sources of this pedestal that have been investigated using high-fidelity numerical particle simulations for two facilities: LCLS and LCLS-II. Furthermore, a new numerical method used to propagate the full three dimensional FEL pulse through the grating based monochromator will be presented. This method leverages a new theoretical model based on a modified Huygens-Fresnell integral that includes non-separable spatio-temporal couplings and temporal dispersive effects up to a quadratic phase.

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)