FEL2017 - Classification: FEL Theory

Paper	Title	Page
WEP048	Coherent Undulator Radiation From a Kicked Electron Beam	515
	J.P. MacArthur, Z. Huang, J. Krzywinski, A.A. Lutman SLAC, Menlo Park, California, USA
	The properties of off-axis radiation from an electron beam that has been kicked off axis are relevant to recent Delta undualtor experiments at LCLS. We calculate the coherent emission from a microbunched beam in the far-field, and compare with simulation. We also present a mechanism for microbunches to tilt toward a new direction of propagation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP048
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WEP073	Lie Map Formalism for FEL Simulation	557
	K. Hwang, J. Qiang LBNL, Berkeley, California, USA
	Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231 Undulator averaging and non-averaging are in compromisation between computational speed and reliability. It is hard to catch the advantages of the both methods simultaneously. In this report, we present a method that compromises the between the averaging and non-averaging methods through Lie map formalism.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP073
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WEP074	Simulations of the Dependence of Harmonic Radiation on Undulator Parameters	560
	G. Penn LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The flux and bandwidth of radiation produced at harmonics of the fundamental are very sensitive to the undulator parameter, and thus the beam energy or undulator period. We look at high-energy XFELs with parameters relevant to the MaRIE FEL design. Both SASE and seeded FELs are considered.
	Poster WEP074 [0.414 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP074
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WEP078	Period-Averaged Symplectic Maps for the FEL Hamiltonian	563
	S.D. Webb RadiaSoft LLC, Boulder, Colorado, USA
	Funding: This work was carried out with support for the United State Department of Energy, Office of Scientific Research, under SBIR contract number DE-SC0017161. Conventional treatments of synchrotron radiation in electron beams treat the radiation as a non-Hamiltonian aspect to the beam dynamics. However, the radiation can be modeled with an electromagnetic Hamiltonian. We present a period-averaged treatment of the FEL problem which includes the Hamiltonian aspects of the coupled electron-radiation dynamics. This approach is then applied to two problems: a 3D split-operator symplectic integrator, and a 1D single-mode FEL treated using Hamiltonian perturbation theory.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP078
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FRB01	Time-Domain Analysis of Attosecond Pulse Generation in an X-Ray Free-Electron Laser	569
	P. Baxevanis, Z. Huang, A. Marinelli SLAC, Menlo Park, California, USA
	The method of enhanced self-amplified spontaneous emission (eSASE) is one of the strongest candidates for the generation of sub-femtosecond X-ray pulses in a free-electron laser. The optimization of an eSASE experiment involves many independent parameters, which makes the exploration of the parameter space with 3-D simulations computationally intensive. Therefore, a robust theoretical analysis of this problem is extremely desirable. We provide a self-consistent, analytical treatment of such a configuration using a one-dimensional, time-dependent FEL model that includes the key effects of linear e-beam chirp and linear undulator taper. Verified via comparison with numerical simulation, our formalism is also utilized in parameter studies that seek to determine the optimum setup of the FEL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB01
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FRB02	Theory and Simulation of FELs with Planar, Helical, and Elliptical Undulators
	H. Freund CSU, Fort Collins, Colorado, USA L.T. Campbell STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom P. Falgari Lime BV, Eindhoven, The Netherlands D.L.A. Grimminck, I. Setya ASML, Veldhoven, The Netherlands J. Henderson, B.W.J. MᶜNeil USTRAT/SUPA, Glasgow, United Kingdom P.J.M. van der Slot Mesa+, Enschede, The Netherlands
	Free-electron lasers (FELs) that produce different polarizations of the output radiation ranging from linear through elliptic to circular polarization are currently under study. In particular, elliptic polarizations are undergoing increased interest. In this paper, we develop an analytic model of the resonant wavelength and JJ-factor for an elliptic undulator as well as both one- and three-dimensional, time-dependent formulations that are capable of simulating elliptic undulators using the PUFFIN and MINERVA simulation codes.,* We present an analytic model of an APPLE-II undulator that is capable of modeling arbitrary elliptic polarizations, and discuss examples of simulation results. * J. Henderson, L. Campbell, H. Freund, and B. McNeil, New J. Phys. 18, 062003 (2016). ** H. Freund, P. van der Slot, D. Grimminck, I. Setya, and P. Falgari, New J. Phys. 19, 023020 (2017).
	Slides FRB02 [0.574 MB]
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FRB03	Dynamics of Superradiant Emission by a Prebunched E-Beam and its Spontaneous Emission Self-Interaction	572
	R. Ianconescu, A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel C. Emma, P. Musumeci UCLA, Los Angeles, USA A. Friedman Ariel University, Ariel, Israel
	Funding: Partial support by US-Israel Binational Science Foundation (BSF) and by Deutsche-Israelische Projektkooperation (DIP). In the context of radiation emission from an electron beam, Dicke's superradiance (SR) is the enhanced coherent spontaneous radiation emission from a prebunched beam, and Stimulated-Superradiance (ST-SR) is the further enhanced emission of the bunched beam in the presence of a phase-matched radiation wave.* These processes are analyzed for undulator radiation in the framework of radiation field mode-excitation theory. In the nonlinear saturation regime the synchronicity of the bunched beam and an injected radiation wave may be sustained by wiggler tapering: Tapering-Enhanced Superradiance (TES) and Tapering-Enhanced Stimulated Superradiance Amplification (TESSA). Identifying these processes is useful for understanding the enhancement of radiative emission in the tapered wiggler section of seeded FELs.,*** The nonlinear formulation of the energy transfer dynamics between the radiation wave and the bunched beam fully conserves energy. This includes conservation of energy without radiation reaction terms in the interesting case of spontaneous self-interaction (no input radiation). * A. Gover, Phys. Rev. ST-AB 8, 030701 (2005). J. Duris et al., New J.Phys. 17 063036 (2015). * E. A. Schneidmiller et al., PRST-AB 18, 03070 (2015). **** C. Emma et al., this conference.
	Slides FRB03 [1.437 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB03
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FRB04	Canonical Formulation of 1D FEL Theory Revisited, Quantized and Applied to Electron Evolution	576
	P.M. Anisimov LANL, Los Alamos, New Mexico, USA
	An original FEL theory relied on quantum analysis of photon generation by relativistic electrons in alternating magnetic field.* In most cases, however, the system of pendulum equations for non-canonical variables and the theory of classical electromagnetism proved to be adequate. As XFELs advance to higher energy photons, quantum effects of electron recoil and shot noise has to be considered. This work presents quantization procedure based on the Hamiltonian formulation of an XFEL interaction in 1D case. The procedure relates the conventional variables to canonical coordinates and momenta and does not require the transformation to the Bambini-Renieri frame. The relation of a field operator to a photon annihilation operator reveals the meaning of the quantum FEL parameter, introduced by Bonifacio, as a number of photons emitted by a single electron before the saturation takes place.* The quantum description is then applied to study how quantum nature of electrons affects the startup of XFEL and how quantum electrons become indistinguishable from a classical ensemble of electrons due to their interaction with a ponderomotive potential of an XFEL. * Madey JMJ 1971 J. Appl. Phys. 42 1906 13. Bambini A and Renieri A 1978 Lett. Nuovo Cimento 21 399-404. * Bonifacio R, Piovella N, Robb G R M and Schiavi A 2006 PRSTAB 9 090701.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB04
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FRB05	Wide Bandwidth, Frequency Modulated Free Electron Laser	581
	L.T. Campbell, B.W.J. MᶜNeil USTRAT/SUPA, Glasgow, United Kingdom
	The resonant frequency of a free electron laser may be modulated via the undulator or electron beam parameters. This modulation may generate sidebands which can subsequently undergo amplification, analogous to frequency modulation in a conventional cavity laser. However, due to the relative slippage of the light through the relativistic electron beam, the FM-FEL system has a more complex behavior than its conventional laser counterpart. The system may be described in the linear regime by a summation over exponential gain modes, allowing the amplification of multiple light frequencies simultaneously. It is found that, with only small, few percent variations of the FEL parameters, one may generate and amplify multiple modes within a frequency bandwidth which greatly exceeds that of normal FEL operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB05
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Coherent Undulator Radiation From a Kicked Electron Beam

515

J.P. MacArthur, Z. Huang, J. Krzywinski, A.A. Lutman
SLAC, Menlo Park, California, USA

The properties of off-axis radiation from an electron beam that has been kicked off axis are relevant to recent Delta undualtor experiments at LCLS. We calculate the coherent emission from a microbunched beam in the far-field, and compare with simulation. We also present a mechanism for microbunches to tilt toward a new direction of propagation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP048

Export •

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

WEP073

Lie Map Formalism for FEL Simulation

557

K. Hwang, J. Qiang
LBNL, Berkeley, California, USA

Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231
Undulator averaging and non-averaging are in compromisation between computational speed and reliability. It is hard to catch the advantages of the both methods simultaneously. In this report, we present a method that compromises the between the averaging and non-averaging methods through Lie map formalism.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP073

Export •

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

WEP074

Simulations of the Dependence of Harmonic Radiation on Undulator Parameters

560

G. Penn
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The flux and bandwidth of radiation produced at harmonics of the fundamental are very sensitive to the undulator parameter, and thus the beam energy or undulator period. We look at high-energy XFELs with parameters relevant to the MaRIE FEL design. Both SASE and seeded FELs are considered.

Poster WEP074 [0.414 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP074

Export •

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

WEP078

Period-Averaged Symplectic Maps for the FEL Hamiltonian

563

S.D. Webb
RadiaSoft LLC, Boulder, Colorado, USA

Funding: This work was carried out with support for the United State Department of Energy, Office of Scientific Research, under SBIR contract number DE-SC0017161.
Conventional treatments of synchrotron radiation in electron beams treat the radiation as a non-Hamiltonian aspect to the beam dynamics. However, the radiation can be modeled with an electromagnetic Hamiltonian. We present a period-averaged treatment of the FEL problem which includes the Hamiltonian aspects of the coupled electron-radiation dynamics. This approach is then applied to two problems: a 3D split-operator symplectic integrator, and a 1D single-mode FEL treated using Hamiltonian perturbation theory.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP078

Export •

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

FRB01

Time-Domain Analysis of Attosecond Pulse Generation in an X-Ray Free-Electron Laser

569

P. Baxevanis, Z. Huang, A. Marinelli
SLAC, Menlo Park, California, USA

The method of enhanced self-amplified spontaneous emission (eSASE) is one of the strongest candidates for the generation of sub-femtosecond X-ray pulses in a free-electron laser. The optimization of an eSASE experiment involves many independent parameters, which makes the exploration of the parameter space with 3-D simulations computationally intensive. Therefore, a robust theoretical analysis of this problem is extremely desirable. We provide a self-consistent, analytical treatment of such a configuration using a one-dimensional, time-dependent FEL model that includes the key effects of linear e-beam chirp and linear undulator taper. Verified via comparison with numerical simulation, our formalism is also utilized in parameter studies that seek to determine the optimum setup of the FEL.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB01

Export •

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

FRB02

Theory and Simulation of FELs with Planar, Helical, and Elliptical Undulators

H. Freund
CSU, Fort Collins, Colorado, USA
L.T. Campbell
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P. Falgari
Lime BV, Eindhoven, The Netherlands
D.L.A. Grimminck, I. Setya
ASML, Veldhoven, The Netherlands
J. Henderson, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom
P.J.M. van der Slot
Mesa+, Enschede, The Netherlands

Free-electron lasers (FELs) that produce different polarizations of the output radiation ranging from linear through elliptic to circular polarization are currently under study. In particular, elliptic polarizations are undergoing increased interest. In this paper, we develop an analytic model of the resonant wavelength and JJ-factor for an elliptic undulator as well as both one- and three-dimensional, time-dependent formulations that are capable of simulating elliptic undulators using the PUFFIN and MINERVA simulation codes.*,** We present an analytic model of an APPLE-II undulator that is capable of modeling arbitrary elliptic polarizations, and discuss examples of simulation results.
* J. Henderson, L. Campbell, H. Freund, and B. McNeil, New J. Phys. 18, 062003 (2016).
** H. Freund, P. van der Slot, D. Grimminck, I. Setya, and P. Falgari, New J. Phys. 19, 023020 (2017).

Slides FRB02 [0.574 MB]

Export •

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

FRB03

Dynamics of Superradiant Emission by a Prebunched E-Beam and its Spontaneous Emission Self-Interaction

572

R. Ianconescu, A. Gover
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
C. Emma, P. Musumeci
UCLA, Los Angeles, USA
A. Friedman
Ariel University, Ariel, Israel

Funding: Partial support by US-Israel Binational Science Foundation (BSF) and by Deutsche-Israelische Projektkooperation (DIP).
In the context of radiation emission from an electron beam, Dicke's superradiance (SR) is the enhanced coherent spontaneous radiation emission from a prebunched beam, and Stimulated-Superradiance (ST-SR) is the further enhanced emission of the bunched beam in the presence of a phase-matched radiation wave.* These processes are analyzed for undulator radiation in the framework of radiation field mode-excitation theory. In the nonlinear saturation regime the synchronicity of the bunched beam and an injected radiation wave may be sustained by wiggler tapering: Tapering-Enhanced Superradiance (TES) and Tapering-Enhanced Stimulated Superradiance Amplification (TESSA).** Identifying these processes is useful for understanding the enhancement of radiative emission in the tapered wiggler section of seeded FELs.***,**** The nonlinear formulation of the energy transfer dynamics between the radiation wave and the bunched beam fully conserves energy. This includes conservation of energy without radiation reaction terms in the interesting case of spontaneous self-interaction (no input radiation).
* A. Gover, Phys. Rev. ST-AB 8, 030701 (2005).
** J. Duris et al., New J.Phys. 17 063036 (2015).
*** E. A. Schneidmiller et al., PRST-AB 18, 03070 (2015).
**** C. Emma et al., this conference.

Slides FRB03 [1.437 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB03

Export •

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

FRB04

Canonical Formulation of 1D FEL Theory Revisited, Quantized and Applied to Electron Evolution

576

P.M. Anisimov
LANL, Los Alamos, New Mexico, USA

An original FEL theory relied on quantum analysis of photon generation by relativistic electrons in alternating magnetic field.* In most cases, however, the system of pendulum equations for non-canonical variables and the theory of classical electromagnetism proved to be adequate. As XFELs advance to higher energy photons, quantum effects of electron recoil and shot noise has to be considered. This work presents quantization procedure based on the Hamiltonian formulation of an XFEL interaction in 1D case. The procedure relates the conventional variables to canonical coordinates and momenta and does not require the transformation to the Bambini-Renieri frame.** The relation of a field operator to a photon annihilation operator reveals the meaning of the quantum FEL parameter, introduced by Bonifacio, as a number of photons emitted by a single electron before the saturation takes place.*** The quantum description is then applied to study how quantum nature of electrons affects the startup of XFEL and how quantum electrons become indistinguishable from a classical ensemble of electrons due to their interaction with a ponderomotive potential of an XFEL.
* Madey JMJ 1971 J. Appl. Phys. 42 1906 13.
** Bambini A and Renieri A 1978 Lett. Nuovo Cimento 21 399-404.
*** Bonifacio R, Piovella N, Robb G R M and Schiavi A 2006 PRSTAB 9 090701.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB04

Export •

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

FRB05

Wide Bandwidth, Frequency Modulated Free Electron Laser

581

L.T. Campbell, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom

The resonant frequency of a free electron laser may be modulated via the undulator or electron beam parameters. This modulation may generate sidebands which can subsequently undergo amplification, analogous to frequency modulation in a conventional cavity laser. However, due to the relative slippage of the light through the relativistic electron beam, the FM-FEL system has a more complex behavior than its conventional laser counterpart. The system may be described in the linear regime by a summation over exponential gain modes, allowing the amplification of multiple light frequencies simultaneously. It is found that, with only small, few percent variations of the FEL parameters, one may generate and amplify multiple modes within a frequency bandwidth which greatly exceeds that of normal FEL operation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB05

Export •

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