IPAC2021 - List of Authors (Marcus, G.)

Paper	Title	Page
MOPAB096	Rocking Curve Imaging Experiment at SSRL 10-2 Beamline	357
	A. Halavanau, R. Arthur, B. Johnson, J.P. MacArthur, G. Marcus, R.A. Margraf, Z. Qu, T. Rabedeau, T. Sato, C.J. Takacs, D. Zhu SLAC, Menlo Park, California, USA
	Stanford Synchrotron Radiation Lightsource (SSRL) serves a wide scientific community with its variety of X-ray capabilities. Recently, we have employed a wiggler source located at beamline 10-2 to perform high resolution rocking curve imaging (RCI) of diamond and silicon crystals. In-house X-ray RCI capability is important for the upcoming cavity-based x-ray source development projects at SLAC, such as cavity-based XFEL (CBXFEL) and X-ray laser oscillator (XLO). In this proceeding, we describe theoretical considerations, and provide experimental results, validating the design of our apparatus. We also provide a plan for future improvements of the RCI@SSRL program.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB096
About •	paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 10 August 2021
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MOPAB097	Two Color Grating design for Soft X-Ray Self-Seeding at LCLS-II	361
	A. Halavanau, D. Cocco, E. Hemsing, G. Marcus, D.S. Morton SLAC, Menlo Park, California, USA G.R. Wilcox Cornell University, Ithaca, New York, USA
	A new grating design is examined for the soft x-ray self-seeding system (SXRSS) at LCLS-II to ultimately produce stable two-color XFEL pulses. The grating performance is analyzed with Fourier optics methods. The final XFEL performance is assessed via full numerical XFEL simulations that substantiate the feasibility of the proposed design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB097
About •	paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 21 August 2021
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TUPAB084	An Empirically-Derived ABCD Matrix for Transverse Dynamics Studies in Seeded Free-Electron Lasers	1573
	R. Robles Stanford University, Stanford, California, USA Z. Huang, G. Marcus SLAC, Menlo Park, California, USA
	Funding: DOE Contract DE-AC02-76SF00515. We present a simple empirical method for deriving an ABCD matrix for studying the transverse dynamics of the radiation field in seeded, high-gain free-electron lasers before saturation. In spite of the inherently nonlinear nature of FEL optical guiding, the ABCD matrix we find is able to predict the evolution of the FEL mode size and centroid to a high degree of accuracy across a large range of input mode characteristics. This scheme enables extremely fast simulation of transverse dynamics, which in turn greatly simplifies numerical studies of seeded FEL systems. Of particular interest in that regard is the x-ray regenerative amplifier free-electron laser, in which the x-ray beam propagates through an optical cavity many hundreds of times, thereby making traditional simulation methods cumbersome and time consuming.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB084
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 11 August 2021
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TUPAB109	Characterization of the X-Ray Angular Pointing Jitter in the LCLS Hard X-ray Undulator Line	1640
	R.A. Margraf, Z. Huang, J.P. MacArthur, G. Marcus, T. Sato, D. Zhu SLAC, Menlo Park, California, USA Z. Huang Stanford University, Stanford, California, USA
	Funding: This work was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515. The angular pointing jitter of X-ray pulses produced by an X-ray Free-Electron Laser (XFEL) depends on both intrinsic properties of the SASE (Self-amplified spontaneous emission) process and jitters in beamline variables such as electron orbit. This jitter is of interest to the Cavity-Based XFEL (CBXFEL)* project at SLAC, which will lase seven undulators inside an X-ray cavity of four diamond Bragg mirrors. The CBXFEL cavity has a narrow angular bandwidth, thus large angular jitters cause X-rays to leak out of the cavity and degrade cavity efficiency. To understand contributors to angular pointing jitter, we studied the pointing jitter of the Linac Coherent Light Source (LCLS) Hard X-ray Undulator line (HXU). Monochromatic and pink X-rays were characterized at the X-ray Pump Probe (XPP) instrument. We found pulses with high monochromatized pulse energy and small electron beam orbit in the undulator have the lowest angular pointing jitter. We present here our measurement results, discuss why these factors correlate with pointing stability, and propose a strategy for CBXFEL to reduce angular pointing jitter and account for angular pointing jitter in cavity efficiency measurements. *Gabriel Marcus et al. "CBXFEL Physics Requirements Document for the Optical cavity Based X-Ray Free Electron Lasers Research and Development Project." SLAC-I-120-103-121-00. Apr 2020.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB109
About •	paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 14 August 2021
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TUPAB110	Measurement and Correction of RF Kicks in the LCLS Accelerator to Improve Two-Bunch Operation	1644
	R.A. Margraf, F.-J. Decker, Z. Huang, G. Marcus SLAC, Menlo Park, California, USA Z. Huang Stanford University, Stanford, California, USA
	Funding: This work was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515. RF kicks, caused by a misalignment of an electron beam and acceleration structure, produce an electron orbit in the accelerator which decreases the final energy of the accelerated electron beam and is detrimental to lasing electron bunches in an X-ray Free Electron Laser (XFEL). RF kicks can depend on the RF waveform of the accelerating structure, so controlling this effect is particularly important when two or more electron bunches are accelerated within an RF fill time. Multibunch modes have been successfully developed for the Linac Coherent Light Source (LCLS) accelerator at SLAC,* and are being continually improved to accommodate new experiments. One such experiment, the Cavity-Based XFEL (CBXFEL)** project will require two electron bunches separated by 218.5 ns which must be identical in energy and orbit. To reduce variation in energy and orbit between the two bunches, we studied the RF kicks produced by each of 75 accelerator segments in the LCLS linac at several RF timings. Here, we discuss these measurements and propose a method to correct RF kicks in the LCLS accelerator using corrector dipoles and quadrupoles. * F.-J. Decker, et al. Recent Developments and Plans for Two Bunch Operation, Proc. of FEL2017, TUP023. ** Gabriel Marcus et al. CBXFEL Physics Requirements Document. SLAC-I-120-103-121-00. 2020.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB110
About •	paper received ※ 19 May 2021 paper accepted ※ 15 June 2021 issue date ※ 29 August 2021
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FRXA07	Ringdown Measured in a Four-Bounce, 20 Meter Hard X-Ray Cavity
	J.P. MacArthur, Z. Huang, J. Krzywiński, G. Marcus, R.A. Margraf, T. Sato, D. Zhu SLAC, Menlo Park, California, USA
	Funding: This work was supported by the Department of Energy under contract DE-AC02-76SF00515 A cavity-based hard x-ray free-electron laser (CBXFEL) could produce fully coherent pulses with a bandwidth several orders of magnitude below the intrinsic bandwidth of SASE. A cavity-based FEL is not a new concept - the first FEL was an oscillator operating at 3.4 um - but single-pass amplification of spontaneous radiation was the fastest path to gigawatt x-ray powers. One unproven component of a CBXFEL is a stable, high reflectivity cavity. To address this deficit we present ring-down measurements in a 20 m round-trip cold cavity operating at 9.8 keV. The cavity is composed of four strain-relief-cut diamond 400 Bragg mirrors and a transmission grating for in/out-coupling. It is a testbed for alignment protocols and component performance under realistic experimental conditions like source instability, optics imperfections, and thermal drift.
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Rocking Curve Imaging Experiment at SSRL 10-2 Beamline

357

A. Halavanau, R. Arthur, B. Johnson, J.P. MacArthur, G. Marcus, R.A. Margraf, Z. Qu, T. Rabedeau, T. Sato, C.J. Takacs, D. Zhu
SLAC, Menlo Park, California, USA

Stanford Synchrotron Radiation Lightsource (SSRL) serves a wide scientific community with its variety of X-ray capabilities. Recently, we have employed a wiggler source located at beamline 10-2 to perform high resolution rocking curve imaging (RCI) of diamond and silicon crystals. In-house X-ray RCI capability is important for the upcoming cavity-based x-ray source development projects at SLAC, such as cavity-based XFEL (CBXFEL) and X-ray laser oscillator (XLO). In this proceeding, we describe theoretical considerations, and provide experimental results, validating the design of our apparatus. We also provide a plan for future improvements of the RCI@SSRL program.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB096

About •

paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 10 August 2021

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

MOPAB097

Two Color Grating design for Soft X-Ray Self-Seeding at LCLS-II

361

A. Halavanau, D. Cocco, E. Hemsing, G. Marcus, D.S. Morton
SLAC, Menlo Park, California, USA
G.R. Wilcox
Cornell University, Ithaca, New York, USA

A new grating design is examined for the soft x-ray self-seeding system (SXRSS) at LCLS-II to ultimately produce stable two-color XFEL pulses. The grating performance is analyzed with Fourier optics methods. The final XFEL performance is assessed via full numerical XFEL simulations that substantiate the feasibility of the proposed design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB097

About •

paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 21 August 2021

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

TUPAB084

An Empirically-Derived ABCD Matrix for Transverse Dynamics Studies in Seeded Free-Electron Lasers

1573

R. Robles
Stanford University, Stanford, California, USA
Z. Huang, G. Marcus
SLAC, Menlo Park, California, USA

Funding: DOE Contract DE-AC02-76SF00515.
We present a simple empirical method for deriving an ABCD matrix for studying the transverse dynamics of the radiation field in seeded, high-gain free-electron lasers before saturation. In spite of the inherently nonlinear nature of FEL optical guiding, the ABCD matrix we find is able to predict the evolution of the FEL mode size and centroid to a high degree of accuracy across a large range of input mode characteristics. This scheme enables extremely fast simulation of transverse dynamics, which in turn greatly simplifies numerical studies of seeded FEL systems. Of particular interest in that regard is the x-ray regenerative amplifier free-electron laser, in which the x-ray beam propagates through an optical cavity many hundreds of times, thereby making traditional simulation methods cumbersome and time consuming.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB084

About •

paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 11 August 2021

Export •

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

TUPAB109

Characterization of the X-Ray Angular Pointing Jitter in the LCLS Hard X-ray Undulator Line

1640

R.A. Margraf, Z. Huang, J.P. MacArthur, G. Marcus, T. Sato, D. Zhu
SLAC, Menlo Park, California, USA
Z. Huang
Stanford University, Stanford, California, USA

Funding: This work was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515.
The angular pointing jitter of X-ray pulses produced by an X-ray Free-Electron Laser (XFEL) depends on both intrinsic properties of the SASE (Self-amplified spontaneous emission) process and jitters in beamline variables such as electron orbit. This jitter is of interest to the Cavity-Based XFEL (CBXFEL)* project at SLAC, which will lase seven undulators inside an X-ray cavity of four diamond Bragg mirrors. The CBXFEL cavity has a narrow angular bandwidth, thus large angular jitters cause X-rays to leak out of the cavity and degrade cavity efficiency. To understand contributors to angular pointing jitter, we studied the pointing jitter of the Linac Coherent Light Source (LCLS) Hard X-ray Undulator line (HXU). Monochromatic and pink X-rays were characterized at the X-ray Pump Probe (XPP) instrument. We found pulses with high monochromatized pulse energy and small electron beam orbit in the undulator have the lowest angular pointing jitter. We present here our measurement results, discuss why these factors correlate with pointing stability, and propose a strategy for CBXFEL to reduce angular pointing jitter and account for angular pointing jitter in cavity efficiency measurements.
*Gabriel Marcus et al. "CBXFEL Physics Requirements Document for the Optical cavity Based X-Ray Free Electron Lasers Research and Development Project." SLAC-I-120-103-121-00. Apr 2020.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB109

About •

paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 14 August 2021

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

TUPAB110

Measurement and Correction of RF Kicks in the LCLS Accelerator to Improve Two-Bunch Operation

1644

R.A. Margraf, F.-J. Decker, Z. Huang, G. Marcus
SLAC, Menlo Park, California, USA
Z. Huang
Stanford University, Stanford, California, USA

Funding: This work was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515.
RF kicks, caused by a misalignment of an electron beam and acceleration structure, produce an electron orbit in the accelerator which decreases the final energy of the accelerated electron beam and is detrimental to lasing electron bunches in an X-ray Free Electron Laser (XFEL). RF kicks can depend on the RF waveform of the accelerating structure, so controlling this effect is particularly important when two or more electron bunches are accelerated within an RF fill time. Multibunch modes have been successfully developed for the Linac Coherent Light Source (LCLS) accelerator at SLAC,* and are being continually improved to accommodate new experiments. One such experiment, the Cavity-Based XFEL (CBXFEL)** project will require two electron bunches separated by 218.5 ns which must be identical in energy and orbit. To reduce variation in energy and orbit between the two bunches, we studied the RF kicks produced by each of 75 accelerator segments in the LCLS linac at several RF timings. Here, we discuss these measurements and propose a method to correct RF kicks in the LCLS accelerator using corrector dipoles and quadrupoles.
* F.-J. Decker, et al. Recent Developments and Plans for Two Bunch Operation, Proc. of FEL2017, TUP023.
** Gabriel Marcus et al. CBXFEL Physics Requirements Document. SLAC-I-120-103-121-00. 2020.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB110

About •

paper received ※ 19 May 2021 paper accepted ※ 15 June 2021 issue date ※ 29 August 2021

Export •

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

FRXA07

Ringdown Measured in a Four-Bounce, 20 Meter Hard X-Ray Cavity

J.P. MacArthur, Z. Huang, J. Krzywiński, G. Marcus, R.A. Margraf, T. Sato, D. Zhu
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Department of Energy under contract DE-AC02-76SF00515
A cavity-based hard x-ray free-electron laser (CBXFEL) could produce fully coherent pulses with a bandwidth several orders of magnitude below the intrinsic bandwidth of SASE. A cavity-based FEL is not a new concept - the first FEL was an oscillator operating at 3.4 um - but single-pass amplification of spontaneous radiation was the fastest path to gigawatt x-ray powers. One unproven component of a CBXFEL is a stable, high reflectivity cavity. To address this deficit we present ring-down measurements in a 20 m round-trip cold cavity operating at 9.8 keV. The cavity is composed of four strain-relief-cut diamond 400 Bragg mirrors and a transmission grating for in/out-coupling. It is a testbed for alignment protocols and component performance under realistic experimental conditions like source instability, optics imperfections, and thermal drift.

Export •

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