FEL2019 - List of Keywords (quadrupole)

Paper	Title	Other Keywords	Page
TUP072	Orbital Angular Momentum from SASE	electron, radiation, FEL, undulator	218
	J.F. Morgan, B.W.J. MᶜNeil USTRAT/SUPA, Glasgow, United Kingdom B.W.J. MᶜNeil, J.F. Morgan, B.D. Muratori, P.H. Williams, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom B.D. Muratori, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A. Wolski The University of Liverpool, Liverpool, United Kingdom
	Radiation with orbital angular momentum, OAM, has many applications such as in imaging systems and microscopic tweezers [1]. The feasibility of generating light with OAM in a free electron laser, FEL, from amplified shot noise in an electron beam is investigated using the FEL simulation code Puffin [2]. This may allow generation of OAM radiation at shorter wavelengths than currently available, as well as the opportunity to incorporate the technique with other SASE manipulation schemes such as mode locking [3]. [1] A. M. Yao and M. J. Padgett, Adv. Opt. Photon. 3, 161(2011) [2] L. T. Campbell and B. W. J. McNeil, Phys. Plasmas. 19, 093119(2012) [3] D. J. Dunning, B. W. J. McNeil, and N. R. Thompson, Phys. Rev. Lett. 110, 104801(2013)
	Poster TUP072 [1.311 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP072
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP067	Development and Commissioning of a Flip Coil System for Measuring Field Integrals	background, software, undulator, MMI	484
	J.E. Baader UNICAMP, Campinas, São Paulo, Brazil
	Funding: CAPES grant numbers 88881.134183/2016-01; DOE contract DE-AC02-76SF00515 in support of the LCLS-II project; and FAEPEX-UNICAMP grant number 519.292/94550-19. Many techniques for measuring magnetic fields are available for accelerator magnets. In general, methods based upon moving wires are suitable for characterizing field harmonics, and first and second field integrals. The flip coil moving wire technique stands out due to simplicity, speed, precision, and accuracy. We aimed to develop a reliable, fast and precise flip coil system capable of characterizing field integrals in the two transverse axes. The coil was a single turn loop made of insulated beryllium copper wire. The width of the loop was 5 mm. The approach of measuring second field integrals by changing the coil’s width at one of the ends was analyzed and included in the system. High-performance motorized stages performed angular and transverse positioning of the coil, while manual stages were used to stretch the wire, execute fine adjustments in its transverse position, and change coil’s geometry. Initial tests with the Earth’s field and also with a reference magnet of 126 Gauss-centimeter (G.cm) demonstrated that the system achieves repeatability of 0.2 G.cm for a 60-cm long coil. This work was carried out for the LCLS-II project at SLAC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP067
About •	paper received ※ 08 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)

THP001	Steffen Hard-Edge Model for Quadrupoles with Extended Fringe-Fields at the European XFEL	FEL, focusing, optics, linac	588
	N. Golubeva, V. Balandin, W. Decking, L. Fröhlich, M. Scholz DESY, Hamburg, Germany
	For modeling of linear focusing properties of quadrupole magnets the conventional rectangular model is commonly used for the design and calculations of the linear beam optics for accelerators. At the European XFEL the quadrupole magnets are described using a more accurate Steffen hard-edge model. In this paper we discuss the application of the Steffen approach for the European XFEL quadrupoles and present the examination of the model with the orbit response matrix technique.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP001
About •	paper received ※ 20 August 2019 paper accepted ※ 25 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP002	Beam Based Alignment in all Undulator Beamlines at European XFEL	FEL, undulator, alignment, electron	592
	M. Scholz, W. Decking DESY, Hamburg, Germany Y. Li EuXFEL, Hamburg, Germany
	The Free Electron Laser European XFEL aims at delivering X-rays from 0.25 keV up to 25 keV out of three SASE undulators. A good overlap of photon and electron beams is indispensable to obtain good lasing performance, especially for the higher photon energies. Thus the quadrupole magnets in the undulators must be aligned as good as possible on a straight line. This can only be realized with a beam based alignment procedure. In this paper we will report on the method that was performed at the European XFEL. We will also discuss our results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP002
About •	paper received ※ 20 August 2019 paper accepted ※ 12 September 2019 issue date ※ 05 November 2019
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THP033	XFEL Isochronous Chicanes: Feasibility Study	dipole, FEL, electron, undulator	658
	N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	FEL schemes such as High-Brightness SASE [1] and Mode-Locking [2] require electron beam delays inserted between undulator sections. These schemes have been shown in simulations to perform most effectively when the electron beam delays are very close to isochronous, i.e. the first order longitudinal dispersion is very small. To minimise the disruption to the FEL process in the inter-undulator gaps, these delays must also be as compact as possible. In this paper we study the maximum longitudinal space that a delay chicane could occupy in an XFEL operating at 6 GeV before the peak power drops below a defined threshold, and we present a limit for the maximum longitudinal dispersion of the delay chicanes. We then present the optical designs of two chicanes that satisfy the requirements of length and isochronicity and show how these designs could be realised practically using small-aperture high-field quadrupoles. [1] PRL 110, 134802 (2013). [2] PRL 100, 203901 (2008).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP033
About •	paper received ※ 16 August 2019 paper accepted ※ 09 September 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	focusing, FEL, undulator, dipole	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)

THP073	Status Update for the High Gain High Efficiency TESSA-266 Experiment	undulator, laser, electron, experiment	730
	Y. Park, D.K. Dang, P.E. Denham, P. Musumeci, N.S. Sudar UCLA, Los Angeles, USA R.B. Agustsson, T.J. Campese, I.I. Gadjev, A.Y. Murokh RadiaBeam, Los Angeles, California, USA C.C. Hall, S.D. Webb RadiaSoft LLC, Boulder, Colorado, USA Y. Sun, A. Zholents ANL, Lemont, Illinois, USA
	Funding: DOE grant No. DE-SC0009914 and DE-SC0018559 Tapering Enhanced Stimulated Superradiant Amplification (TESSA) allows to increase the efficiency of Free Electron Laser (FEL) based radiation generation from ~0.1% to 10% by using intense seed laser pulses, strongly tapered undulators and prebunched electron beams [1]. Initial results validating this method have already been obtained at 10 µm wavelength at Brookhaven National Laboratory [2]. We will present the design of an experiment to demonstrate the TESSA scheme at high gain and shorter wavelength (266 nm) using the APS injector linac at Argonne National Labor-atory (ANL) to obtain conversion efficiency of up to 10%. Undulator and focusing lattice design, as well as beam dynamics and diagnostics for this experiment will be discussed. An extension of the experiment to include the possibility of multi-bunch linac operation and an optical cavity around the undulator to operate in the TESSO regime will also be presented [3]. [1] J. Duris et al., New J. Phys. 17 063036 (2015) [2] N Sudar et al., Physical review letters, 117, 174801 (2016) [3] J. Duris et al., Physical Review Accelerators and Beams 21, 080705 (2018)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP073
About •	paper received ※ 20 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)

Paper

Title

Other Keywords

Page

TUP072

Orbital Angular Momentum from SASE

electron, radiation, FEL, undulator

218

J.F. Morgan, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom
B.W.J. MᶜNeil, J.F. Morgan, B.D. Muratori, P.H. Williams, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B.D. Muratori, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A. Wolski
The University of Liverpool, Liverpool, United Kingdom

Radiation with orbital angular momentum, OAM, has many applications such as in imaging systems and microscopic tweezers [1]. The feasibility of generating light with OAM in a free electron laser, FEL, from amplified shot noise in an electron beam is investigated using the FEL simulation code Puffin [2]. This may allow generation of OAM radiation at shorter wavelengths than currently available, as well as the opportunity to incorporate the technique with other SASE manipulation schemes such as mode locking [3].
[1] A. M. Yao and M. J. Padgett, Adv. Opt. Photon. 3, 161(2011)
[2] L. T. Campbell and B. W. J. McNeil, Phys. Plasmas. 19, 093119(2012)
[3] D. J. Dunning, B. W. J. McNeil, and N. R. Thompson, Phys. Rev. Lett. 110, 104801(2013)

Poster TUP072 [1.311 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP072

About •

paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

Export •

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

WEP067

Development and Commissioning of a Flip Coil System for Measuring Field Integrals

background, software, undulator, MMI

484

J.E. Baader
UNICAMP, Campinas, São Paulo, Brazil

Funding: CAPES grant numbers 88881.134183/2016-01; DOE contract DE-AC02-76SF00515 in support of the LCLS-II project; and FAEPEX-UNICAMP grant number 519.292/94550-19.
Many techniques for measuring magnetic fields are available for accelerator magnets. In general, methods based upon moving wires are suitable for characterizing field harmonics, and first and second field integrals. The flip coil moving wire technique stands out due to simplicity, speed, precision, and accuracy. We aimed to develop a reliable, fast and precise flip coil system capable of characterizing field integrals in the two transverse axes. The coil was a single turn loop made of insulated beryllium copper wire. The width of the loop was 5 mm. The approach of measuring second field integrals by changing the coil’s width at one of the ends was analyzed and included in the system. High-performance motorized stages performed angular and transverse positioning of the coil, while manual stages were used to stretch the wire, execute fine adjustments in its transverse position, and change coil’s geometry. Initial tests with the Earth’s field and also with a reference magnet of 126 Gauss-centimeter (G.cm) demonstrated that the system achieves repeatability of 0.2 G.cm for a 60-cm long coil. This work was carried out for the LCLS-II project at SLAC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP067

About •

paper received ※ 08 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)

THP001

Steffen Hard-Edge Model for Quadrupoles with Extended Fringe-Fields at the European XFEL

FEL, focusing, optics, linac

588

N. Golubeva, V. Balandin, W. Decking, L. Fröhlich, M. Scholz
DESY, Hamburg, Germany

For modeling of linear focusing properties of quadrupole magnets the conventional rectangular model is commonly used for the design and calculations of the linear beam optics for accelerators. At the European XFEL the quadrupole magnets are described using a more accurate Steffen hard-edge model. In this paper we discuss the application of the Steffen approach for the European XFEL quadrupoles and present the examination of the model with the orbit response matrix technique.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP001

About •

paper received ※ 20 August 2019 paper accepted ※ 25 August 2019 issue date ※ 05 November 2019

Export •

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

THP002

Beam Based Alignment in all Undulator Beamlines at European XFEL

FEL, undulator, alignment, electron

592

M. Scholz, W. Decking
DESY, Hamburg, Germany
Y. Li
EuXFEL, Hamburg, Germany

The Free Electron Laser European XFEL aims at delivering X-rays from 0.25 keV up to 25 keV out of three SASE undulators. A good overlap of photon and electron beams is indispensable to obtain good lasing performance, especially for the higher photon energies. Thus the quadrupole magnets in the undulators must be aligned as good as possible on a straight line. This can only be realized with a beam based alignment procedure. In this paper we will report on the method that was performed at the European XFEL. We will also discuss our results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP002

About •

paper received ※ 20 August 2019 paper accepted ※ 12 September 2019 issue date ※ 05 November 2019

Export •

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

THP033

XFEL Isochronous Chicanes: Feasibility Study

dipole, FEL, electron, undulator

658

N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

FEL schemes such as High-Brightness SASE [1] and Mode-Locking [2] require electron beam delays inserted between undulator sections. These schemes have been shown in simulations to perform most effectively when the electron beam delays are very close to isochronous, i.e. the first order longitudinal dispersion is very small. To minimise the disruption to the FEL process in the inter-undulator gaps, these delays must also be as compact as possible. In this paper we study the maximum longitudinal space that a delay chicane could occupy in an XFEL operating at 6 GeV before the peak power drops below a defined threshold, and we present a limit for the maximum longitudinal dispersion of the delay chicanes. We then present the optical designs of two chicanes that satisfy the requirements of length and isochronicity and show how these designs could be realised practically using small-aperture high-field quadrupoles.
[1] PRL 110, 134802 (2013).
[2] PRL 100, 203901 (2008).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP033

About •

paper received ※ 16 August 2019 paper accepted ※ 09 September 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

focusing, FEL, undulator, dipole

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)

THP073

Status Update for the High Gain High Efficiency TESSA-266 Experiment

undulator, laser, electron, experiment

730

Y. Park, D.K. Dang, P.E. Denham, P. Musumeci, N.S. Sudar
UCLA, Los Angeles, USA
R.B. Agustsson, T.J. Campese, I.I. Gadjev, A.Y. Murokh
RadiaBeam, Los Angeles, California, USA
C.C. Hall, S.D. Webb
RadiaSoft LLC, Boulder, Colorado, USA
Y. Sun, A. Zholents
ANL, Lemont, Illinois, USA

Funding: DOE grant No. DE-SC0009914 and DE-SC0018559
Tapering Enhanced Stimulated Superradiant Amplification (TESSA) allows to increase the efficiency of Free Electron Laser (FEL) based radiation generation from ~0.1% to 10% by using intense seed laser pulses, strongly tapered undulators and prebunched electron beams [1]. Initial results validating this method have already been obtained at 10 µm wavelength at Brookhaven National Laboratory [2]. We will present the design of an experiment to demonstrate the TESSA scheme at high gain and shorter wavelength (266 nm) using the APS injector linac at Argonne National Labor-atory (ANL) to obtain conversion efficiency of up to 10%. Undulator and focusing lattice design, as well as beam dynamics and diagnostics for this experiment will be discussed. An extension of the experiment to include the possibility of multi-bunch linac operation and an optical cavity around the undulator to operate in the TESSO regime will also be presented [3].
[1] J. Duris et al., New J. Phys. 17 063036 (2015)
[2] N Sudar et al., Physical review letters, 117, 174801 (2016)
[3] J. Duris et al., Physical Review Accelerators and Beams 21, 080705 (2018)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP073

About •

paper received ※ 20 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)