FEL2019 - List of Authors (MacArthur, J.P.)

Paper	Title	Page
MOD02	Microbunch Rotation and Coherent Undulator Radiation from a Kicked Electron Beam
	J.P. MacArthur SLAC, Menlo Park, California, USA
	Microbunches form perpendicular to the electron travel direction, and the conventional understanding is that they shear rather than rotate in response to a transverse kick, locking FEL facilities into a single-user operating mode. We show that microbunches rotate toward the new direction of travel if the electron beam is kicked and defocused. We provide evidence that microbunch rotation explains the unexpectedly large amount of off-axis radiation observed during experiments at the Linac Coherent Light Source. We demonstrate that LCLS can be multiplexed into at least three soft X-ray beams using this principle. Finally, we report on a more sophisticated scheme of offset quadrupoles that was used to produce two distinct hard X-ray spots at LCLS.
	Slides MOD02 [25.347 MB]
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TUP032	Regenerative Amplification for a Hard X-Ray Free-Electron Laser	118
	G. Marcus, Y. Ding, Y. Feng, A. Halavanau, Z. Huang, J. Krzywiński, J.P. MacArthur, R.A. Margraf, T.O. Raubenheimer, D. Zhu SLAC, Menlo Park, California, USA V. Fiadonu Santa Clara University, Santa Clara, 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. An X-ray regenerative amplifier FEL (XRAFEL) utilizes an X-ray crystal cavity to provide optical feedback to the entrance of a high-gain undulator. An XRAFEL system leverages gain-guiding in the undulator to reduce the cavity alignment tolerances and targets the production of longitudinally coherent and high peak power and brightness X-ray pulses that could significantly enhance the performance of a standard single-pass SASE amplifier. The successful implementation of an X-ray cavity in the XRAFEL scheme requires the demonstration of X-ray optical components that can either satisfy large output coupling constraints or passively output a large fraction of the amplified coherent radiation. Here, we present new schemes to either actively Q-switch a diamond Bragg crystal through lattice constant manipulation or passively output couple a large fraction of the stored cavity radiation through controlled FEL microbunch rotation. A beamline design study, cavity stability analysis, and optimization will be presented illustrating the performance of potential XRAFEL configurations at LCLS-II/-HE using high-fidelity simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP032
About •	paper received ※ 24 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019
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TUP033	Q-Switching of X-Ray Optical Cavities by Using Boron Doped Buried Layer Under a Surface of a Diamond Crystal	122
	J. Krzywiński, Y. Feng, A. Halavanau, Z. Huang, A.M. Kiss, J.P. MacArthur, G. Marcus, T. Sato, D. Zhu SLAC, Menlo Park, California, USA
	Improvement of the longitudinal coherence of X-ray Free Electron Lasers has been the subject of many recent investigations. The XFEL oscillator (XFELO) and Regenerative Amplifier Free-Electron Laser (RAFEL) schemes offer a pathway to fully coherent, high brightness X-ray radiation. The XFELO and RAFEL consist of a high repetition rate electron beam, an undulator and an X-ray crystal cavity to provide optical feedback. The X-ray cavity will be based on diamond crystals in order to manage a high thermal load. We are investigating a ’Q switching’ mechanism that involves the use of a ’Bragg switch’ to dump the X-ray pulse energy built-up inside an X-ray cavity. In particular, one can use an optical laser to manipulate the diamond crystal lattice constant to control the crystal reflectivity and transmission. It has been shown that a 9 MeV focused boron beam can create a buried layer, approximately 5 microns below surface, with a boron concentration up to 10²¹ atoms/cm³. Here, we present simulations showing that absorbing laser pulses by a buried layer under the crystal surface would allow creating a transient temperature profile which would be well suited for the ’Q switching’ scheme.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP033
About •	paper received ※ 21 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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TUD04	Cavity-Based Free-Electron Laser Research and Development: A Joint Argonne National Laboratory and SLAC National Laboratory Collaboration	282
	G. Marcus, F.-J. Decker, G.L. Gassner, A. Halavanau, J.B. Hastings, Z. Huang, Y. Liu, J.P. MacArthur, R.A. Margraf, T.O. Raubenheimer, A. Sakdinawat, T.-F. Tan, D. Zhu SLAC, Menlo Park, California, USA J.W.J. Anton, L. Assoufid, K. Goetze, W.G. Jansma, S.P. Kearney, K. Kim, R.R. Lindberg, A. Miceli, X. Shi, D. Shu, Yu. Shvyd’ko, J.P. Sullivan, M. White ANL, Lemont, Illinois, USA B. Lantz Stanford University, Stanford, California, USA
	One solution for producing longitudinally coherent FEL pulses is to store and recirculate the output of an amplifier in an X-ray cavity so that the X-ray pulse can interact with following fresh electron bunches over many passes. The X-ray FEL oscillator (XFELO) and the X-ray regenerative amplifier FEL (XRAFEL) concepts use this technique and rely on the same fundamental ingredients to realize their full capability. Both schemes require a high repetition rate electron beam, an undulator to provide FEL gain, and an X-ray cavity to recirculate and monochromatize the radiation. The shared infrastructure, complementary performance characteristics, and potentially transformative FEL properties of the XFELO and XRAFEL have brought together a joint Argonne National Laboratory (ANL) and SLAC National Laboratory (SLAC) collaboration aimed at enabling these schemes at LCLS-II. We present plans to install a rectangular X-ray cavity in the LCLS-II undulator hall and perform experiments employing 2-bunch copper RF linac accelerated electron beams. This includes performing cavity ring-down measurements and 2-pass gain measurements for both the low-gain XFELO and the high-gain RAFEL schemes.
	Slides TUD04 [12.425 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUD04
About •	paper received ※ 25 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP036	Microbunch Rotation for Hard X-Ray Beam Multiplexing	665
	R.A. Margraf, Z. Huang, J.P. MacArthur, G. Marcus SLAC, Menlo Park, California, USA X.J. Deng TUB, Beijing, People’s Republic of China Z. Huang, J.P. MacArthur, R.A. Margraf 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. Electron bunches in an undulator develop periodic density modulations, or microbunches, which enable the exponential gain of X-ray power in a SASE FEL. Many FEL applications could benefit from the ability to preserve microbunching through a dipole kick. For example, X-ray beam multiplexing can be achieved if electron bunches are kicked into separate beamlines and allowed to lase in a final undulator. The microbunches developed in upstream undulators, if properly rotated, will lase off axis, producing radiation at an angle offset from the initial beam axis. Microbunch rotation with soft X-rays was previously published and demonstrated experimentally [1], multiplexing LCLS into three X-ray beams. Additional 2018 data demonstrated multiplexing of hard X-rays. Here we describe efforts to reproduce these hard X-ray experiments using an analytical model and Genesis simulations. Our goal is to apply microbunch rotation to out-coupling from a cavity-based XFEL, (RAFEL/XFELO) [2]. [1] J. P. MacArthur et al., Physical Review X 8, 041036 (2018). [2] G. Marcus et al. Poster TUD04 presented at FEL2019 (2019).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP036
About •	paper received ※ 24 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THD02	Attosecond Pulses from Enhanced SASE at LCLS
	A. Marinelli, P.H. Bucksbaum, E. Champenois, J. Cryan, T.D.C. Driver, J.P. Duris, Z. Huang, A.A. Lutman, J.P. MacArthur, Z. Zhang SLAC, Menlo Park, California, USA Z. Huang, S. Li, J.P. MacArthur Stanford University, Stanford, California, USA M. Kling, P. Rosenberger LMU, Garching, Germany A. Zholents ANL, Lemont, Illinois, USA
	In my talk I will report the generation and diagnostic of GW-scale soft X-ray attosecond pulses with a current-enhanced X-ray free-electron laser. Our method is based on the enhaced SASE scheme, where an electron bunch with high-current spike is generated by the interaction of the relativistic electrons with a high-power infrared pulse. The X-ray pulses generated by the compressed electron beam are diagnosed with angular photoelectron streaking, and have a mean pulse duration of 350 attoseconds. Our source has a peak brightness that is 6 orders of magnitude larger than any other source of isolated attosecond pulses in the soft X-ray spectral region. This unique combination of high intensity, high photon energy and pulse duration enables the investigation of valence electron dynamics with non-linear spectroscopy and single-shot imaging. I will also discuss the generation of two-color attosecond pulses and our future plans for attosecond science at LCLS-II.
	Slides THD02 [0.260 MB]
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

MOD02

Microbunch Rotation and Coherent Undulator Radiation from a Kicked Electron Beam

J.P. MacArthur
SLAC, Menlo Park, California, USA

Microbunches form perpendicular to the electron travel direction, and the conventional understanding is that they shear rather than rotate in response to a transverse kick, locking FEL facilities into a single-user operating mode. We show that microbunches rotate toward the new direction of travel if the electron beam is kicked and defocused. We provide evidence that microbunch rotation explains the unexpectedly large amount of off-axis radiation observed during experiments at the Linac Coherent Light Source. We demonstrate that LCLS can be multiplexed into at least three soft X-ray beams using this principle. Finally, we report on a more sophisticated scheme of offset quadrupoles that was used to produce two distinct hard X-ray spots at LCLS.

Slides MOD02 [25.347 MB]

Export •

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

TUP032

Regenerative Amplification for a Hard X-Ray Free-Electron Laser

118

G. Marcus, Y. Ding, Y. Feng, A. Halavanau, Z. Huang, J. Krzywiński, J.P. MacArthur, R.A. Margraf, T.O. Raubenheimer, D. Zhu
SLAC, Menlo Park, California, USA
V. Fiadonu
Santa Clara University, Santa Clara, 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.
An X-ray regenerative amplifier FEL (XRAFEL) utilizes an X-ray crystal cavity to provide optical feedback to the entrance of a high-gain undulator. An XRAFEL system leverages gain-guiding in the undulator to reduce the cavity alignment tolerances and targets the production of longitudinally coherent and high peak power and brightness X-ray pulses that could significantly enhance the performance of a standard single-pass SASE amplifier. The successful implementation of an X-ray cavity in the XRAFEL scheme requires the demonstration of X-ray optical components that can either satisfy large output coupling constraints or passively output a large fraction of the amplified coherent radiation. Here, we present new schemes to either actively Q-switch a diamond Bragg crystal through lattice constant manipulation or passively output couple a large fraction of the stored cavity radiation through controlled FEL microbunch rotation. A beamline design study, cavity stability analysis, and optimization will be presented illustrating the performance of potential XRAFEL configurations at LCLS-II/-HE using high-fidelity simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP032

About •

paper received ※ 24 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019

Export •

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

TUP033

Q-Switching of X-Ray Optical Cavities by Using Boron Doped Buried Layer Under a Surface of a Diamond Crystal

122

J. Krzywiński, Y. Feng, A. Halavanau, Z. Huang, A.M. Kiss, J.P. MacArthur, G. Marcus, T. Sato, D. Zhu
SLAC, Menlo Park, California, USA

Improvement of the longitudinal coherence of X-ray Free Electron Lasers has been the subject of many recent investigations. The XFEL oscillator (XFELO) and Regenerative Amplifier Free-Electron Laser (RAFEL) schemes offer a pathway to fully coherent, high brightness X-ray radiation. The XFELO and RAFEL consist of a high repetition rate electron beam, an undulator and an X-ray crystal cavity to provide optical feedback. The X-ray cavity will be based on diamond crystals in order to manage a high thermal load. We are investigating a ’Q switching’ mechanism that involves the use of a ’Bragg switch’ to dump the X-ray pulse energy built-up inside an X-ray cavity. In particular, one can use an optical laser to manipulate the diamond crystal lattice constant to control the crystal reflectivity and transmission. It has been shown that a 9 MeV focused boron beam can create a buried layer, approximately 5 microns below surface, with a boron concentration up to 10²¹ atoms/cm³. Here, we present simulations showing that absorbing laser pulses by a buried layer under the crystal surface would allow creating a transient temperature profile which would be well suited for the ’Q switching’ scheme.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP033

About •

paper received ※ 21 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

Export •

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

TUD04

Cavity-Based Free-Electron Laser Research and Development: A Joint Argonne National Laboratory and SLAC National Laboratory Collaboration

282

G. Marcus, F.-J. Decker, G.L. Gassner, A. Halavanau, J.B. Hastings, Z. Huang, Y. Liu, J.P. MacArthur, R.A. Margraf, T.O. Raubenheimer, A. Sakdinawat, T.-F. Tan, D. Zhu
SLAC, Menlo Park, California, USA
J.W.J. Anton, L. Assoufid, K. Goetze, W.G. Jansma, S.P. Kearney, K. Kim, R.R. Lindberg, A. Miceli, X. Shi, D. Shu, Yu. Shvyd’ko, J.P. Sullivan, M. White
ANL, Lemont, Illinois, USA
B. Lantz
Stanford University, Stanford, California, USA

One solution for producing longitudinally coherent FEL pulses is to store and recirculate the output of an amplifier in an X-ray cavity so that the X-ray pulse can interact with following fresh electron bunches over many passes. The X-ray FEL oscillator (XFELO) and the X-ray regenerative amplifier FEL (XRAFEL) concepts use this technique and rely on the same fundamental ingredients to realize their full capability. Both schemes require a high repetition rate electron beam, an undulator to provide FEL gain, and an X-ray cavity to recirculate and monochromatize the radiation. The shared infrastructure, complementary performance characteristics, and potentially transformative FEL properties of the XFELO and XRAFEL have brought together a joint Argonne National Laboratory (ANL) and SLAC National Laboratory (SLAC) collaboration aimed at enabling these schemes at LCLS-II. We present plans to install a rectangular X-ray cavity in the LCLS-II undulator hall and perform experiments employing 2-bunch copper RF linac accelerated electron beams. This includes performing cavity ring-down measurements and 2-pass gain measurements for both the low-gain XFELO and the high-gain RAFEL schemes.

Slides TUD04 [12.425 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUD04

About •

paper received ※ 25 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

Export •

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

THP036

Microbunch Rotation for Hard X-Ray Beam Multiplexing

665

R.A. Margraf, Z. Huang, J.P. MacArthur, G. Marcus
SLAC, Menlo Park, California, USA
X.J. Deng
TUB, Beijing, People’s Republic of China
Z. Huang, J.P. MacArthur, R.A. Margraf
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.
Electron bunches in an undulator develop periodic density modulations, or microbunches, which enable the exponential gain of X-ray power in a SASE FEL. Many FEL applications could benefit from the ability to preserve microbunching through a dipole kick. For example, X-ray beam multiplexing can be achieved if electron bunches are kicked into separate beamlines and allowed to lase in a final undulator. The microbunches developed in upstream undulators, if properly rotated, will lase off axis, producing radiation at an angle offset from the initial beam axis. Microbunch rotation with soft X-rays was previously published and demonstrated experimentally [1], multiplexing LCLS into three X-ray beams. Additional 2018 data demonstrated multiplexing of hard X-rays. Here we describe efforts to reproduce these hard X-ray experiments using an analytical model and Genesis simulations. Our goal is to apply microbunch rotation to out-coupling from a cavity-based XFEL, (RAFEL/XFELO) [2].
[1] J. P. MacArthur et al., Physical Review X 8, 041036 (2018).
[2] G. Marcus et al. Poster TUD04 presented at FEL2019 (2019).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP036

About •

paper received ※ 24 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019

Export •

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

THD02

Attosecond Pulses from Enhanced SASE at LCLS

A. Marinelli, P.H. Bucksbaum, E. Champenois, J. Cryan, T.D.C. Driver, J.P. Duris, Z. Huang, A.A. Lutman, J.P. MacArthur, Z. Zhang
SLAC, Menlo Park, California, USA
Z. Huang, S. Li, J.P. MacArthur
Stanford University, Stanford, California, USA
M. Kling, P. Rosenberger
LMU, Garching, Germany
A. Zholents
ANL, Lemont, Illinois, USA

In my talk I will report the generation and diagnostic of GW-scale soft X-ray attosecond pulses with a current-enhanced X-ray free-electron laser. Our method is based on the enhaced SASE scheme, where an electron bunch with high-current spike is generated by the interaction of the relativistic electrons with a high-power infrared pulse. The X-ray pulses generated by the compressed electron beam are diagnosed with angular photoelectron streaking, and have a mean pulse duration of 350 attoseconds. Our source has a peak brightness that is 6 orders of magnitude larger than any other source of isolated attosecond pulses in the soft X-ray spectral region. This unique combination of high intensity, high photon energy and pulse duration enables the investigation of valence electron dynamics with non-linear spectroscopy and single-shot imaging. I will also discuss the generation of two-color attosecond pulses and our future plans for attosecond science at LCLS-II.

Slides THD02 [0.260 MB]

Export •

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