FEL2015 - List of Keywords (free-electron-laser)

Paper	Title	Other Keywords	Page
TUP003	Threshold of a Mirror-less Photonic Free Electron Laser Oscillator Pumped by One or More Electron Beams	electron, laser, radiation, plasma	327
	P.J.M. van der Slot, K.-J. Boller, A. Strooisma Mesa+, Enschede, The Netherlands
	Funding: This research is supported by the Dutch Technology Foundation STW, which is part of the Netherlands Organisation for Scientific Research, and which is partly funded by the Ministry of Economic Affairs Transmitting electrons through a photonic crystal can result in stimulated emission and the generation of coherent Cerenkov radiation. Here we consider a photonic-crystal slab consisting of a two-dimensional, periodic array of bars inside a rectangular waveguide. By appropriately tapering the bars at both ends of the slab, we numerically show that an electromagnetic wave can be transmitted through the waveguide filled with the photonic-crystal slab with close to zero reflection. Furthermore, the photonic-crystal slab allows transmission of electrons in the form of one or more beams. By appropriately designing the photonic-crystal slab, we obtain a backward wave interaction at low electron-beam energy of around 15 kV, that results in distributed feedback of the radiation on the electrons without any external mirrors being present. Here we discuss the dynamics of the laser oscillator near threshold and numerically show that the threshold current can be distributed over multiple electron beams, resulting in a lower current per beam.
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TUP005	A Mirror-Less, Multi-Beam Photonic Free-Electron Laser Oscillator Pumped Far Beyond Threshold	electron, laser, radiation, feedback	334
	P.J.M. van der Slot, K.-J. Boller, A. Strooisma Mesa+, Enschede, The Netherlands
	Funding: This research is supported by the Dutch Technology Foundation STW, which is part of the Netherlands Organisation for Scientific Research, and which is partly funded by the Ministry of Economic Affairs In a photonic free-electron laser electrons are transmitted through a photonic crystal in the form of one or multiple electron beams to generate coherent Cerenkov radiation. Here we consider a photonic-crystal slab consisting of a two-dimensional, periodic array of bars inside a rectangular waveguide, with both ends tapered to provide complete transmission of an electromagnetic wave. By appropriately designing the photonic-crystal slab, we obtain a backward wave interaction at low electron beam energy of around 15 kV, that results in distributed feedback of the radiation on the electrons without any external mirrors being present. Here we numerically study the dynamics of the laser oscillator when pumped far beyond threshold with one or multiple electron beams. We show that using multiple beams with the same total current provide better suppression of higher-order modes and can produce more output power, compared to the laser pumped by a single beam of the same total current.
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TUP030	Time Dependent Study for an X-ray FEL Oscillator at LCLS-II	cavity, electron, photon, undulator	433
	J. Zemella DESY, Hamburg, Germany W.M. Fawley, T.J. Maxwell SLAC, Menlo Park, California, USA R.R. Lindberg ANL, Argonne, Illinois, USA
	The LCLS-II with its high repetition rate and high quality beam will be capable of driving an X-ray free electron laser oscillator at higher harmonics in the hard X-ray regime (0.1 nm). The oscillator consists of a low loss X-ray crystal cavity using diamond Bragg crystals with meV bandwidth. The expected average spectral flux has been estimated to be at least two orders of magnitude greater than present synchrotron-based sources with highly stable, coherent pulses of duration 1 ps or less for applications in Mössbauer spectroscopy and inelastic x-ray scattering. A more detailed study of the start up of a fifth-harmonic X-ray FEL oscillator at LCLS-II will be presented with full, time-dependent simulations.
	Poster TUP030 [0.619 MB]
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TUP041	Simultaneous Operation of Three Laser Systems at the FLASH Photoinjector	laser, electron, cathode, operation	459
	S. Schreiber, C. Grün, K. Klose, J. Rönsch-Schulenburg, B. Steffen DESY, Hamburg, Germany
	The free-electron laser facility FLASH at DESY (Hamburg, Germany) operates two undulator beamlines simultaneously. Both undulator beamlines are driven by a common linear superconducting accelerator with a beam energy of up to 1.25 GeV. The superconducting technology allows the acceleration of trains of several hundred microsecond spaced bunches with a repetition rate of 10 Hz. A fast kickers-septum system is installed to distribute one part of the electron bunch train to FLASH1 and the other part to FLASH2 keeping the full 10 Hz repetition rate for both beamlines. In order to deliver different beam properties to each beamline, the FLASH photoinjector uses two independent laser systems to generate different bunch pattern and bunch charges. One laser serves the FLASH1 beamline, the other the FLASH2 beamline. A third laser with adjus ö laser pulse duration is used to generate ultra-short bunches for single spike lasing.
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WEP016	Free Electron Lasers in 2015	FEL, electron, undulator, laser	625
	K. R. Cohn, J. Blau, W.B. Colson, J.W. Ng, M.J. Price NPS, Monterey, California, USA
	Funding: This work has been supported by the High Energy Laser Joint Technology Office. Thirty-nine years after the first operation of the short wavelength free electron laser (FEL) at Stanford University, there continue to be many important experiments, proposed experiments, and user facilities around the world. Properties of FELs in the infrared, visible, UV, and x-ray wavelength regimes are tabulated and discussed.
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WEP054	Control of Gap Dependent Phase Errors on the Undulator Segments for the European XFEL	undulator, laser, electron, FEL	685
	Y. Li, J. Pflüger XFEL. EU, Hamburg, Germany
	Strong magnetic forces in long undulators always result in some girder deformation. This problem gets more serious in long gap tuneable undulators. In addition the deformation varies with changing forces at different gaps resulting in gap dependent phase errors. For the undulators for the European XFEL this problem has been studied thoroughly and quantitatively. A compensation method is presented which uses a combination of suitable shims and pole height tuning. It is exemplified by tuning one of the undulator segments for the European XFEL back to specs.
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WEP085	Conceptual Theory of Spontaneous and Taper-Enhanced Superradiance and Stimulated Superradiance	radiation, electron, wiggler, FEL	746
	A. Gover, R. Ianconescu 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: We acknowledge partial support by the U.S. Israel Binational Science Foundation (BSF)Jerusalem, Israel In the context of radiation emission from an electron beam Dicke's superradiance (SR) is the enhanced radiation emission from a pre-bunched beam. Stimulated Superradiance (ST-SR) is the further enhanced emission of the bunched beam in the presence of a phase-matched radiation wave. These processes were analyzed for Undulator radiation in the framework of radiation field mode-excitation theory[1]. In the nonlinear saturation regime the synchronism of the bunched beam and an injected radiation wave may be sustained by wiggler tapering [2]. Same processes are instrumental also in enhancing the radiative emission in the tapered wiggler section of seeded FEL[3]. In a long tapered wiggler the diffraction of the emitted radiation wave is not negligible even at Angstroms wavelengths (as in LCLS). A Fresnel diffraction model was provided in [4] for the SR process only. Here we outline the fundamental physical concepts of Spontaneous Superradiadce (SR), Stimulated Superradiance (ST-SR), Taper-Enhanced Superradiance (TES) and Taper-Enhanced Stimulated Superradiance Amplification (TESSA), and compare their Fourier and Phasor formulations in the radiation mode expansion and free-diffraction models. Detailed further analysis can provide better design concepts of high power FELs and improved tapering strategy for enhancing the power of seeded short wavelength FELs 1. A. Gover, PR ST-AB 8, (030701) ; (030702) (2005) 2. J. Duris et al., arxiv 2015. 3. Y. Jiao et al., PR ST-AB 15 050704 2012 4. E.A. Schneidmiller, M.V. Yurkov, PR ST-AB 18, 030705 (2015)
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Paper

Title

Other Keywords

Page

TUP003

Threshold of a Mirror-less Photonic Free Electron Laser Oscillator Pumped by One or More Electron Beams

electron, laser, radiation, plasma

327

P.J.M. van der Slot, K.-J. Boller, A. Strooisma
Mesa+, Enschede, The Netherlands

Funding: This research is supported by the Dutch Technology Foundation STW, which is part of the Netherlands Organisation for Scientific Research, and which is partly funded by the Ministry of Economic Affairs
Transmitting electrons through a photonic crystal can result in stimulated emission and the generation of coherent Cerenkov radiation. Here we consider a photonic-crystal slab consisting of a two-dimensional, periodic array of bars inside a rectangular waveguide. By appropriately tapering the bars at both ends of the slab, we numerically show that an electromagnetic wave can be transmitted through the waveguide filled with the photonic-crystal slab with close to zero reflection. Furthermore, the photonic-crystal slab allows transmission of electrons in the form of one or more beams. By appropriately designing the photonic-crystal slab, we obtain a backward wave interaction at low electron-beam energy of around 15 kV, that results in distributed feedback of the radiation on the electrons without any external mirrors being present. Here we discuss the dynamics of the laser oscillator near threshold and numerically show that the threshold current can be distributed over multiple electron beams, resulting in a lower current per beam.

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TUP005

A Mirror-Less, Multi-Beam Photonic Free-Electron Laser Oscillator Pumped Far Beyond Threshold

electron, laser, radiation, feedback

334

P.J.M. van der Slot, K.-J. Boller, A. Strooisma
Mesa+, Enschede, The Netherlands

Funding: This research is supported by the Dutch Technology Foundation STW, which is part of the Netherlands Organisation for Scientific Research, and which is partly funded by the Ministry of Economic Affairs
In a photonic free-electron laser electrons are transmitted through a photonic crystal in the form of one or multiple electron beams to generate coherent Cerenkov radiation. Here we consider a photonic-crystal slab consisting of a two-dimensional, periodic array of bars inside a rectangular waveguide, with both ends tapered to provide complete transmission of an electromagnetic wave. By appropriately designing the photonic-crystal slab, we obtain a backward wave interaction at low electron beam energy of around 15 kV, that results in distributed feedback of the radiation on the electrons without any external mirrors being present. Here we numerically study the dynamics of the laser oscillator when pumped far beyond threshold with one or multiple electron beams. We show that using multiple beams with the same total current provide better suppression of higher-order modes and can produce more output power, compared to the laser pumped by a single beam of the same total current.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUP030

Time Dependent Study for an X-ray FEL Oscillator at LCLS-II

cavity, electron, photon, undulator

433

J. Zemella
DESY, Hamburg, Germany
W.M. Fawley, T.J. Maxwell
SLAC, Menlo Park, California, USA
R.R. Lindberg
ANL, Argonne, Illinois, USA

The LCLS-II with its high repetition rate and high quality beam will be capable of driving an X-ray free electron laser oscillator at higher harmonics in the hard X-ray regime (0.1 nm). The oscillator consists of a low loss X-ray crystal cavity using diamond Bragg crystals with meV bandwidth. The expected average spectral flux has been estimated to be at least two orders of magnitude greater than present synchrotron-based sources with highly stable, coherent pulses of duration 1 ps or less for applications in Mössbauer spectroscopy and inelastic x-ray scattering. A more detailed study of the start up of a fifth-harmonic X-ray FEL oscillator at LCLS-II will be presented with full, time-dependent simulations.

Poster TUP030 [0.619 MB]

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TUP041

Simultaneous Operation of Three Laser Systems at the FLASH Photoinjector

laser, electron, cathode, operation

459

S. Schreiber, C. Grün, K. Klose, J. Rönsch-Schulenburg, B. Steffen
DESY, Hamburg, Germany

The free-electron laser facility FLASH at DESY (Hamburg, Germany) operates two undulator beamlines simultaneously. Both undulator beamlines are driven by a common linear superconducting accelerator with a beam energy of up to 1.25 GeV. The superconducting technology allows the acceleration of trains of several hundred microsecond spaced bunches with a repetition rate of 10 Hz. A fast kickers-septum system is installed to distribute one part of the electron bunch train to FLASH1 and the other part to FLASH2 keeping the full 10 Hz repetition rate for both beamlines. In order to deliver different beam properties to each beamline, the FLASH photoinjector uses two independent laser systems to generate different bunch pattern and bunch charges. One laser serves the FLASH1 beamline, the other the FLASH2 beamline. A third laser with adjus ö laser pulse duration is used to generate ultra-short bunches for single spike lasing.

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WEP016

Free Electron Lasers in 2015

FEL, electron, undulator, laser

625

K. R. Cohn, J. Blau, W.B. Colson, J.W. Ng, M.J. Price
NPS, Monterey, California, USA

Funding: This work has been supported by the High Energy Laser Joint Technology Office.
Thirty-nine years after the first operation of the short wavelength free electron laser (FEL) at Stanford University, there continue to be many important experiments, proposed experiments, and user facilities around the world. Properties of FELs in the infrared, visible, UV, and x-ray wavelength regimes are tabulated and discussed.

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reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEP054

Control of Gap Dependent Phase Errors on the Undulator Segments for the European XFEL

undulator, laser, electron, FEL

685

Y. Li, J. Pflüger
XFEL. EU, Hamburg, Germany

Strong magnetic forces in long undulators always result in some girder deformation. This problem gets more serious in long gap tuneable undulators. In addition the deformation varies with changing forces at different gaps resulting in gap dependent phase errors. For the undulators for the European XFEL this problem has been studied thoroughly and quantitatively. A compensation method is presented which uses a combination of suitable shims and pole height tuning. It is exemplified by tuning one of the undulator segments for the European XFEL back to specs.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEP085

Conceptual Theory of Spontaneous and Taper-Enhanced Superradiance and Stimulated Superradiance

radiation, electron, wiggler, FEL

746

A. Gover, R. Ianconescu
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: We acknowledge partial support by the U.S. Israel Binational Science Foundation (BSF)Jerusalem, Israel
In the context of radiation emission from an electron beam Dicke's superradiance (SR) is the enhanced radiation emission from a pre-bunched beam. Stimulated Superradiance (ST-SR) is the further enhanced emission of the bunched beam in the presence of a phase-matched radiation wave. These processes were analyzed for Undulator radiation in the framework of radiation field mode-excitation theory[1]. In the nonlinear saturation regime the synchronism of the bunched beam and an injected radiation wave may be sustained by wiggler tapering [2]. Same processes are instrumental also in enhancing the radiative emission in the tapered wiggler section of seeded FEL[3]. In a long tapered wiggler the diffraction of the emitted radiation wave is not negligible even at Angstroms wavelengths (as in LCLS). A Fresnel diffraction model was provided in [4] for the SR process only. Here we outline the fundamental physical concepts of Spontaneous Superradiadce (SR), Stimulated Superradiance (ST-SR), Taper-Enhanced Superradiance (TES) and Taper-Enhanced Stimulated Superradiance Amplification (TESSA), and compare their Fourier and Phasor formulations in the radiation mode expansion and free-diffraction models. Detailed further analysis can provide better design concepts of high power FELs and improved tapering strategy for enhancing the power of seeded short wavelength FELs
1. A. Gover, PR ST-AB 8, (030701) ; (030702) (2005)
2. J. Duris et al., arxiv 2015.
3. Y. Jiao et al., PR ST-AB 15 050704 2012
4. E.A. Schneidmiller, M.V. Yurkov, PR ST-AB 18, 030705 (2015)

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