FEL2015 - List of Keywords (photon)

Paper	Title	Other Keywords	Page
MOB02	X-Ray FEL R&D: Brighter, Better and Cheaper	FEL, undulator, electron, radiation	7
	Z. Huang SLAC, Menlo Park, California, USA
	The X-ray free-electron lasers (FELs), with nine to ten orders of magnitude improvement in peak brightness over the third-generation light sources, have demonstrated remarkable scientific capabilities. Despite the early success, X-ray FELs can still undergo dramatic transformations with accelerator and FEL R&D. In this talk, I will show examples of recent R&D efforts to increase X-ray coherence and brightness, to obtain better control of X-ray temporal and spectral properties, and to develop concepts for compact coherent sources.
	Slides MOB02 [18.004 MB]
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

MOP013	The Fermi Seeded FEL Facility: Operational Experience and Future Perspectives	FEL, experiment, laser, electron	57
	L. Giannessi, E. Allaria, L. Badano, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, M. Coreno, R. Cucini, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, P. Finetti, P. Furlan Radivo, G. Gaio, D. Gauthier, F. Gelmetti, F. Iazzourene, M. Kiskinova, S. Krecic, M. Lonza, N. Mahne, M. Manfredda, C. Masciovecchio, M. Milloch, F. Parmigiani, E. Pedersoli, G. Penco, L. Pivetta, O. Plekan, M. Predonzani, K.C. Prince, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, E. Roussel, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, M. Svandrlik, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	FERMI is the seeded FEL user facility in Trieste, Italy, producing photons from the VUV to the soft X-rays with a high degree of coherence and spectral stability. Both FEL lines, FEL-1 and FEL-2, are available for users, down to the shortest wavelength of 4 nm. We report on the completion of the commissioning of the high energy FEL line, FEL-2, on the most recent progress obtained on FEL-1 and on the operational experience for users, in particular those requiring specific FEL configurations, such as two-colour experiments. We will also give a perspective on the improvements and upgrades which have been triggered based on our experience, aiming to maintain as well as to constantly improve the performance of the facility for our user community.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

MOP014	Status of the Soft X-Ray FEL User Facility FLASH	electron, operation, experiment, FEL	61
	K. Honkavaara, B. Faatz, J. Feldhaus, S. Schreiber, R. Treusch, M. Vogt DESY, Hamburg, Germany
	Since 10 years FLASH at DESY (Hamburg, Germany) has provided high brilliance FEL radiation at XUV and soft X-ray wavelengths for user experiments. Recently FLASH has been upgraded with a second undulator beamline, FLASH2, whose commissioning takes place in parallel of the user operation on FLASH1. This paper summarizes the performance of the FLASH facility during the last user period from January 2014 to April 2015.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

MOP082	New Soft X-Ray Undulator Line Using 10 GeV Electron Beam in PAL-XFEL	undulator, electron, linac, simulation	237
	C.H. Shim, I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea Y.W. Parc PAL, Pohang, Kyungbuk, Republic of Korea
	PAL-XFEL is designed to have five undulator lines and only two undulator lines, the HXR undulator line with 10 GeV electron beam and the SXR undulator line with 3.15 GeV electron beam, will be installed during phase I. A photon beam energy from 0.28 to 1.24 keV will be provided at the SXR undulator line and different range from 2 to 20 keV will be supplied at the HXR undulator line. According to existing schedule, however, photon beam energy from 1.24 to 2 keV won't be provided in PAL-XFEL. In this research, new soft X-ray undulator line for PAL-XFEL using 10 GeV electron beam in main linac is proposed to cover the vacant photon energy. Four candidates are evaluated by estimating and comparing FEL performances using Ming Xie's formula.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

MOP085	Scheme to Increase the Output Average Spectral Flux of the European XFEL at 14.4 keV	FEL, undulator, electron, scattering	251
	V. Kocharyan, E. Saldin DESY, Hamburg, Germany G. Geloni XFEL. EU, Hamburg, Germany
	Inelastic X-ray scattering and nuclear resonance scattering are limited by the photon flux available at SR sources, up to 10¹⁰ ph/s/meV at 14.4 keV. A thousand-fold increase may be obtained by exploiting high repetition rate self-seeded pulses at the European XFEL. We report on a feasibility study for an optimized configuration of the SASE2 beamline combining self-seeding and undulator tapering at 14.4 keV. One should perform monochromatization at 7.2 keV by self-seeding, and amplify the seed in the first part of the output undulator. Before saturation, the electron beam is considerably bunched at the 2nd harmonic. A second part of the output undulator tuned to 14.4 keV can thus be used to obtain saturation at this energy. One can further prolong the exchange of energy between the photon and the electron beam by tapering the last part of the output undulator. Start-to-end simulations demonstrate that self-seeding, combined with undulator tapering, allows one to achieve more than a hundred-fold increase in average spectral flux compared with the nominal SASE regime at saturation, resulting in a spectral flux of order 10¹³ ph/s/meV. A more detailed description of this study can be found in. G. Geloni, V. Kocharyan and E.~Saldin, "Scheme to increase the output average spectral flux of the European XFEL at 14.4 keV", DESY 15-141 (2015).
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

MOP086	Novel Opportunities for Sub-meV Inelastic X-Ray Scattering Experiments at High-Repetition Rate Self-seeded XFELs	undulator, radiation, optics, scattering	257
	O.V. Chubar BNL, Upton, Long Island, New York, USA G. Geloni, A. Madsen XFEL. EU, Hamburg, Germany V. Kocharyan, E. Saldin, S. Serkez DESY, Hamburg, Germany Yu. Shvyd'ko ANL, Argonne, Ilinois, USA J. Sutter DLS, Oxfordshire, United Kingdom
	Inelastic x-ray scattering (IXS) is an important tool for studies of equilibrium dynamics in condensed matter. A new spectrometer recently proposed for ultra-high-resolution IXS (UHRIX) has achieved 0.6 meV and 0.25/nm spectral and momentum Transfer resolutions, respectively. However, further improvements down to 0.1 meV and 0.02/nm are required to close the gap in energy-momentum space between high and low frequency probes. We Show that this goal can be achieved by further improvements in x-ray optics and by increasing the spectral flux of the incident x-ray pulses. UHRIX performs best at energies from 5 to 10 keV, where a combination of self-seeding and undulator tapering at the SASE2 beamline of the European XFEL promises up to a hundred-fold increase in average spectral flux compared to nominal SASE pulses at saturation, or three orders of magnitude more than possible with storage-ring based radiation sources. Wave-optics propagation shows that about 7·10¹² ph/s in a 90-microeV bandwidth can be achieved on the sample. This will provide unique new possibilities for IXS. Extended information about our work can be found in. Y. Shvyd'ko et al., Nature Communications 5:4219 (2014). ** O. Chubar et al., ‘Novel opportunities for sub-meV inelastic X-ray scattering at high-repetition rate self-seeded X-ray free-electron lasers', http://arxiv.org/abs/1508.02632, DESY 15-140, (2015).
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUA02	Suppression of FEL Lasing by a Seeded Microbunching Instability	electron, laser, FEL, undulator	289
	C. Lechner, A. Azima, M. Drescher, L.L. Lazzarino, Th. Maltezopoulos, V. Miltchev, T. Plath, J. Rönsch-Schulenburg, J. Roßbach Uni HH, Hamburg, Germany S. Ackermann, J. Bödewadt, G. Brenner, M. Dohlus, N. Ekanayake, T. Golz, T. Laarmann, T. Limberg, E. Schneidmiller, N. Stojanovic, M.V. Yurkov DESY, Hamburg, Germany K.E. Hacker, S. Khan, R. Molo DELTA, Dortmund, Germany
	Funding: Supported by Federal Ministry of Education and Research of Germany under contract No. 05K10PE1, 05K10PE3, 05K13GU4, and 05K13PE3 and the German Research Foundation programme graduate school GRK1355. Collective effects and instabilities due to longitudinal space charge and coherent synchrotron radiation can degrade the quality of the ultra-relativistic, high-brightness electron bunches driving free-electron lasers (FELs). In this contribution, we demonstrate suppression of FEL lasing induced by a laser-triggered microbunching instability at the free-electron laser FLASH. The interaction between the electron bunches and the 800-nm laser pulses takes place in an undulator upstream of the FEL undulators. A significant decrease of XUV photon pulse energies has been observed in coincidence with the laser-electron overlap in the modulator. We discuss the underlying mechanisms based on longitudinal space charge amplification (LSCA) [E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST Accel. Beams 13, 110701 (2010)] and present measurements.
	Slides TUA02 [14.298 MB]
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUA04	First Simultaneous Operation of Two Sase Beamlines in FLASH	undulator, operation, electron, FEL	297
	M. Scholz, B. Faatz, S. Schreiber, J. Zemella DESY, Hamburg, Germany
	FLASH2, the second undulator beamline of the FLASH FEL user facility at DESY (Hamburg, Germany) is under commissioning. Its first lasing was achieved in August 2014. FLASH is the first soft X-ray FEL operating 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. Fast kickers and a septum are installed to distribute one part of the electron bunch train to FLASH1 and the other part to FLASH2 with full repetition rate. The commissioning of FLASH2 takes place primarily in parallel to FLASH1 user operation. Various beam optics measurements has been carried out in order to ensure the required electron beam quality for efficient SASE generation. This paper reports the status of the FLASH2 commissioning.
	Slides TUA04 [9.655 MB]
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, undulator, free-electron-laser	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]
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUP056	Design Challenge and Strategy for the LCLS-II High Repetition Rate X-ray FEL Photon Stoppers	FEL, simulation, radiation, synchrotron	493
	Y. Feng, J.T. Delor, J. Krzywinski, P.A. Montanez, E. Ortiz, T.O. Raubenheimer, M. Rowen SLAC, Menlo Park, California, USA
	Funding: Portions of this research were carried out at the LCLS at the SLAC National Accelerator Laboratory. LCLS is an User Facility operated for the US DOE Office of Science by Stanford University. Future high repetition rate X-ray FELs such as the European XFEL and LCLS-II presents new challenges to photon diagnostics as well as essential beamline components. In addition to these devices having to sustain the high peak power of a single-pulse FEL radiation, they must also be capable of handling the enormous power density of tens to hundreds of watts over an area as small as 0.1 mm X mm. In this talk, I will discuss the potential impact of high power FEL operation on performance of a gas attenuator and the design challenges to beam intercepting components such as a collimator or stopper.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUP080	Terahertz Source Utilizing Resonant Coherent Diffraction Radiation at KEK ERL Test Accelerator	radiation, cavity, extraction, operation	547
	Y. Honda, A. Aryshev, M. Shevelev, M. Shimada KEK, Ibaraki, Japan
	An energy recovery linac test accelerator, cERL, has been developing at KEK. It can produce a high repetition rate short bunched electron beam in a continuous operation mode. We propose to develop a high power THz radiation source at the return loop of the cERL. Coherent diffraction radiation of THz regime is emitted when an electron bunch passes through a conductive mirror with a beam hole at the center. If we form an optical cavity using two mirrors facing each other and the cavity length coincides with the bunch repetition rate, the coherent diffraction radiation of multiple bunches adds up coherently in the cavity. By extracting the power through transmission of one of the mirrors, we can realize a high power and high efficiency THz source. We discuss performance of the source assuming the beam parameters of cERL.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEP022	Photon Energies beyond the Selenium K-Edge at LCLS	FEL, electron, operation, linac	630
	F.-J. Decker, W.S. Colocho, Y. Ding, R.H. Iverson, H. Loos, J. Sheppard, H. Smith, J.L. Turner SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515. The Linac Coherent Light Source (LCLS) was designed for a photon energies of 830 eV to 8.3 keV. This range was widened and up to 11.2 keV photons were already delivered for users. The Selenium K-edge at 12.6578 keV is very interesting since Selenium can replace Sulfur in biological structures and then that structure could be precisely measured. To reach this the electron energy would need to be raised by about 6% which initially didn't seem possible. The trick is to change the final compression scheme from a high correlated energy spread and moderate R56 in the compression chicane to moderate energy spread and high R56. The same bunch length can be achieved and RF energy is freed up, so the overall beam energy can be raised. Photons up to an energy of 12.82 keV (1.3% above the K-edge) with a pulse intensity of 0.93 mJ were achieved. The photon energy spread with this setup is wider at around 40-50 eV FWHM, since less correlated energy spread is left after the compression.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEP023	Two Bunches with ns-Separation with LCLS	laser, timing, experiment, controls	634
	F.-J. Decker, S. Gilevich, Z. Huang, H. Loos, A. Marinelli, C.A. Stan, J.L. Turner, Z. Van Hoover, S. Vetter SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515. The Linac Coherent Light Source (LCLS) delivers typically one bunch. Two bunches are interesting for pump / probe experiments. Two electron bunches with ps separation have been already produced using a split and delay in the laser which produces them on the gun cathode. Here we present the combination of two lasers with a combiner, this allows any time separation and is it limited to RF bucket spacing so far to about 40 ns limited by the setup of our beam containment system. Different beam energies were also provided and the most challenging part was a transverse separation of a few σs for the two beams. Although this setup was very jittery a successful user experiment was accomplished.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEP025	Effect of Microbunching on Seeding Schemes for LCLS-II	laser, electron, undulator, radiation	639
	G. Penn, J. Qiang LBNL, Berkeley, California, USA P. Emma, E. Hemsing, Z. Huang, G. Marcus, T.O. Raubenheimer, L. Wang SLAC, Menlo Park, 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. External seeding and self-seeding schemes are particularly sensitive to distortions and fluctuations in the electron beam profile. Wakefields and the microbunching instability are important sources of such imperfections. Even at modest levels, their influence can degrade the spectrum and decrease the output brightness. These effects are evaluated for seeded FELs at the soft X-ray beam line of LCLS-II. FEL simulations are performed in GENESIS based on various realistic electron distributions obtained using the IMPACT tracking code. The sensitivity depends on both the seeding scheme and the output wavelength.
	Poster WEP025 [0.962 MB]
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEP052	Studies of LCLS FEL Divergence	undulator, simulation, electron, quadrupole	681
	J.L. Turner, P. Baxevanis, F.-J. Decker, Y. Ding, Z. Huang, J. Krzywinski, H. Loos, G. Marcus, N.P. Norvell SLAC, Menlo Park, California, USA
	Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515 Simulations show various impacts on x-ray divergence. With the motivation to maximize intensity at the focus, these beam studies were designed to study parameter space and beam qualities impacting divergence, and therefore aperture related clipping and diffraction. With multiple simultaneous users, beam constraints increase, requiring an improving knowledge of the mechanism of impact of changing parameters. These studies have that goal in order to improve beam control.
	Poster WEP052 [1.010 MB]
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WED03	Photon Diagnostics and Photon Beamlines Installations at the European XFEL	diagnostics, beam-transport, radiation, vacuum	764
	J. Grünert, B. Baranasic, J. Buck, F. Dietrich, M. Dommach, W. Freund, A. Koch, N.G. Kujala, J. Liu, S. Molodtsov, M. Planas, H. Sinn XFEL. EU, Hamburg, Germany
	The European X-ray Free-Electron-Laser (XFEL. EU) is a new a 4th generation light facility which will deliver radiation with femtosecond and sub-Ångström resolution at MHz repetition rates, and is currently under construction in the Hamburg metropolitan area in Germany. Special diagnostics [1,2] for spontaneous radiation analysis is required to tune towards the lasing condition. Once lasing is achieved, diagnostic imagers [3], online monitors [4], and the photon beam transport system [5] need to cope with extreme radiation intensities. In 2015 the installation of machine equipment in the photon area of the facility is in full swing. This contribution presents the progress on final assemblies of photon diagnostics, the installation status of these devices as well as of the beam transport system, and recent design developments for diagnostic spectrometers and temporal diagnostics. [1] J. Grünert, XFEL. EU TR-2012-003(2012) [2] W. Freund, XFEL. EU TN-2014-001-01(2014) [3] A. Koch, Proc. SPIE 95121R(2015) [4] J. Buck et al., Proc. SPIE 85040U(2012) [5] H. Sinn et al., XFEL. EU TR-2012-006(2012)
	Slides WED03 [14.557 MB]
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOB02

X-Ray FEL R&D: Brighter, Better and Cheaper

FEL, undulator, electron, radiation

7

Z. Huang
SLAC, Menlo Park, California, USA

The X-ray free-electron lasers (FELs), with nine to ten orders of magnitude improvement in peak brightness over the third-generation light sources, have demonstrated remarkable scientific capabilities. Despite the early success, X-ray FELs can still undergo dramatic transformations with accelerator and FEL R&D. In this talk, I will show examples of recent R&D efforts to increase X-ray coherence and brightness, to obtain better control of X-ray temporal and spectral properties, and to develop concepts for compact coherent sources.

Slides MOB02 [18.004 MB]

Export •

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

MOP013

The Fermi Seeded FEL Facility: Operational Experience and Future Perspectives

FEL, experiment, laser, electron

57

L. Giannessi, E. Allaria, L. Badano, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, M. Coreno, R. Cucini, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, P. Finetti, P. Furlan Radivo, G. Gaio, D. Gauthier, F. Gelmetti, F. Iazzourene, M. Kiskinova, S. Krecic, M. Lonza, N. Mahne, M. Manfredda, C. Masciovecchio, M. Milloch, F. Parmigiani, E. Pedersoli, G. Penco, L. Pivetta, O. Plekan, M. Predonzani, K.C. Prince, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, E. Roussel, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, M. Svandrlik, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

FERMI is the seeded FEL user facility in Trieste, Italy, producing photons from the VUV to the soft X-rays with a high degree of coherence and spectral stability. Both FEL lines, FEL-1 and FEL-2, are available for users, down to the shortest wavelength of 4 nm. We report on the completion of the commissioning of the high energy FEL line, FEL-2, on the most recent progress obtained on FEL-1 and on the operational experience for users, in particular those requiring specific FEL configurations, such as two-colour experiments. We will also give a perspective on the improvements and upgrades which have been triggered based on our experience, aiming to maintain as well as to constantly improve the performance of the facility for our user community.

Export •

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

MOP014

Status of the Soft X-Ray FEL User Facility FLASH

electron, operation, experiment, FEL

61

K. Honkavaara, B. Faatz, J. Feldhaus, S. Schreiber, R. Treusch, M. Vogt
DESY, Hamburg, Germany

Since 10 years FLASH at DESY (Hamburg, Germany) has provided high brilliance FEL radiation at XUV and soft X-ray wavelengths for user experiments. Recently FLASH has been upgraded with a second undulator beamline, FLASH2, whose commissioning takes place in parallel of the user operation on FLASH1. This paper summarizes the performance of the FLASH facility during the last user period from January 2014 to April 2015.

Export •

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

MOP082

New Soft X-Ray Undulator Line Using 10 GeV Electron Beam in PAL-XFEL

undulator, electron, linac, simulation

237

C.H. Shim, I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
Y.W. Parc
PAL, Pohang, Kyungbuk, Republic of Korea

PAL-XFEL is designed to have five undulator lines and only two undulator lines, the HXR undulator line with 10 GeV electron beam and the SXR undulator line with 3.15 GeV electron beam, will be installed during phase I. A photon beam energy from 0.28 to 1.24 keV will be provided at the SXR undulator line and different range from 2 to 20 keV will be supplied at the HXR undulator line. According to existing schedule, however, photon beam energy from 1.24 to 2 keV won't be provided in PAL-XFEL. In this research, new soft X-ray undulator line for PAL-XFEL using 10 GeV electron beam in main linac is proposed to cover the vacant photon energy. Four candidates are evaluated by estimating and comparing FEL performances using Ming Xie's formula.

Export •

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

MOP085

Scheme to Increase the Output Average Spectral Flux of the European XFEL at 14.4 keV

FEL, undulator, electron, scattering

251

V. Kocharyan, E. Saldin
DESY, Hamburg, Germany
G. Geloni
XFEL. EU, Hamburg, Germany

Inelastic X-ray scattering and nuclear resonance scattering are limited by the photon flux available at SR sources, up to 10¹⁰ ph/s/meV at 14.4 keV. A thousand-fold increase may be obtained by exploiting high repetition rate self-seeded pulses at the European XFEL. We report on a feasibility study for an optimized configuration of the SASE2 beamline combining self-seeding and undulator tapering at 14.4 keV. One should perform monochromatization at 7.2 keV by self-seeding, and amplify the seed in the first part of the output undulator. Before saturation, the electron beam is considerably bunched at the 2nd harmonic. A second part of the output undulator tuned to 14.4 keV can thus be used to obtain saturation at this energy. One can further prolong the exchange of energy between the photon and the electron beam by tapering the last part of the output undulator. Start-to-end simulations demonstrate that self-seeding, combined with undulator tapering, allows one to achieve more than a hundred-fold increase in average spectral flux compared with the nominal SASE regime at saturation, resulting in a spectral flux of order 10¹³ ph/s/meV. A more detailed description of this study can be found in*.
* G. Geloni, V. Kocharyan and E.~Saldin, "Scheme to increase the output average spectral flux of the European XFEL at 14.4 keV", DESY 15-141 (2015).

Export •

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

MOP086

Novel Opportunities for Sub-meV Inelastic X-Ray Scattering Experiments at High-Repetition Rate Self-seeded XFELs

undulator, radiation, optics, scattering

257

O.V. Chubar
BNL, Upton, Long Island, New York, USA
G. Geloni, A. Madsen
XFEL. EU, Hamburg, Germany
V. Kocharyan, E. Saldin, S. Serkez
DESY, Hamburg, Germany
Yu. Shvyd'ko
ANL, Argonne, Ilinois, USA
J. Sutter
DLS, Oxfordshire, United Kingdom

Inelastic x-ray scattering (IXS) is an important tool for studies of equilibrium dynamics in condensed matter. A new spectrometer recently proposed for ultra-high-resolution IXS (UHRIX) has achieved 0.6 meV and 0.25/nm spectral and momentum Transfer resolutions, respectively*. However, further improvements down to 0.1 meV and 0.02/nm are required to close the gap in energy-momentum space between high and low frequency probes. We Show that this goal can be achieved by further improvements in x-ray optics and by increasing the spectral flux of the incident x-ray pulses. UHRIX performs best at energies from 5 to 10 keV, where a combination of self-seeding and undulator tapering at the SASE2 beamline of the European XFEL promises up to a hundred-fold increase in average spectral flux compared to nominal SASE pulses at saturation, or three orders of magnitude more than possible with storage-ring based radiation sources. Wave-optics propagation shows that about 7·10¹² ph/s in a 90-microeV bandwidth can be achieved on the sample. This will provide unique new possibilities for IXS. Extended information about our work can be found in**.
* Y. Shvyd'ko et al., Nature Communications 5:4219 (2014).
** O. Chubar et al., ‘Novel opportunities for sub-meV inelastic X-ray scattering at high-repetition rate self-seeded X-ray free-electron lasers', http://arxiv.org/abs/1508.02632, DESY 15-140, (2015).

Export •

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

TUA02

Suppression of FEL Lasing by a Seeded Microbunching Instability

electron, laser, FEL, undulator

289

C. Lechner, A. Azima, M. Drescher, L.L. Lazzarino, Th. Maltezopoulos, V. Miltchev, T. Plath, J. Rönsch-Schulenburg, J. Roßbach
Uni HH, Hamburg, Germany
S. Ackermann, J. Bödewadt, G. Brenner, M. Dohlus, N. Ekanayake, T. Golz, T. Laarmann, T. Limberg, E. Schneidmiller, N. Stojanovic, M.V. Yurkov
DESY, Hamburg, Germany
K.E. Hacker, S. Khan, R. Molo
DELTA, Dortmund, Germany

Funding: Supported by Federal Ministry of Education and Research of Germany under contract No. 05K10PE1, 05K10PE3, 05K13GU4, and 05K13PE3 and the German Research Foundation programme graduate school GRK1355.
Collective effects and instabilities due to longitudinal space charge and coherent synchrotron radiation can degrade the quality of the ultra-relativistic, high-brightness electron bunches driving free-electron lasers (FELs). In this contribution, we demonstrate suppression of FEL lasing induced by a laser-triggered microbunching instability at the free-electron laser FLASH. The interaction between the electron bunches and the 800-nm laser pulses takes place in an undulator upstream of the FEL undulators. A significant decrease of XUV photon pulse energies has been observed in coincidence with the laser-electron overlap in the modulator. We discuss the underlying mechanisms based on longitudinal space charge amplification (LSCA) [E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST Accel. Beams 13, 110701 (2010)] and present measurements.

Slides TUA02 [14.298 MB]

Export •

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

TUA04

First Simultaneous Operation of Two Sase Beamlines in FLASH

undulator, operation, electron, FEL

297

M. Scholz, B. Faatz, S. Schreiber, J. Zemella
DESY, Hamburg, Germany

FLASH2, the second undulator beamline of the FLASH FEL user facility at DESY (Hamburg, Germany) is under commissioning. Its first lasing was achieved in August 2014. FLASH is the first soft X-ray FEL operating 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. Fast kickers and a septum are installed to distribute one part of the electron bunch train to FLASH1 and the other part to FLASH2 with full repetition rate. The commissioning of FLASH2 takes place primarily in parallel to FLASH1 user operation. Various beam optics measurements has been carried out in order to ensure the required electron beam quality for efficient SASE generation. This paper reports the status of the FLASH2 commissioning.

Slides TUA04 [9.655 MB]

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, undulator, free-electron-laser

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]

Export •

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

TUP056

Design Challenge and Strategy for the LCLS-II High Repetition Rate X-ray FEL Photon Stoppers

FEL, simulation, radiation, synchrotron

493

Y. Feng, J.T. Delor, J. Krzywinski, P.A. Montanez, E. Ortiz, T.O. Raubenheimer, M. Rowen
SLAC, Menlo Park, California, USA

Funding: Portions of this research were carried out at the LCLS at the SLAC National Accelerator Laboratory. LCLS is an User Facility operated for the US DOE Office of Science by Stanford University.
Future high repetition rate X-ray FELs such as the European XFEL and LCLS-II presents new challenges to photon diagnostics as well as essential beamline components. In addition to these devices having to sustain the high peak power of a single-pulse FEL radiation, they must also be capable of handling the enormous power density of tens to hundreds of watts over an area as small as 0.1 mm X mm. In this talk, I will discuss the potential impact of high power FEL operation on performance of a gas attenuator and the design challenges to beam intercepting components such as a collimator or stopper.

Export •

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

TUP080

Terahertz Source Utilizing Resonant Coherent Diffraction Radiation at KEK ERL Test Accelerator

radiation, cavity, extraction, operation

547

Y. Honda, A. Aryshev, M. Shevelev, M. Shimada
KEK, Ibaraki, Japan

An energy recovery linac test accelerator, cERL, has been developing at KEK. It can produce a high repetition rate short bunched electron beam in a continuous operation mode. We propose to develop a high power THz radiation source at the return loop of the cERL. Coherent diffraction radiation of THz regime is emitted when an electron bunch passes through a conductive mirror with a beam hole at the center. If we form an optical cavity using two mirrors facing each other and the cavity length coincides with the bunch repetition rate, the coherent diffraction radiation of multiple bunches adds up coherently in the cavity. By extracting the power through transmission of one of the mirrors, we can realize a high power and high efficiency THz source. We discuss performance of the source assuming the beam parameters of cERL.

Export •

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

WEP022

Photon Energies beyond the Selenium K-Edge at LCLS

FEL, electron, operation, linac

630

F.-J. Decker, W.S. Colocho, Y. Ding, R.H. Iverson, H. Loos, J. Sheppard, H. Smith, J.L. Turner
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) was designed for a photon energies of 830 eV to 8.3 keV. This range was widened and up to 11.2 keV photons were already delivered for users. The Selenium K-edge at 12.6578 keV is very interesting since Selenium can replace Sulfur in biological structures and then that structure could be precisely measured. To reach this the electron energy would need to be raised by about 6% which initially didn't seem possible. The trick is to change the final compression scheme from a high correlated energy spread and moderate R56 in the compression chicane to moderate energy spread and high R56. The same bunch length can be achieved and RF energy is freed up, so the overall beam energy can be raised. Photons up to an energy of 12.82 keV (1.3% above the K-edge) with a pulse intensity of 0.93 mJ were achieved. The photon energy spread with this setup is wider at around 40-50 eV FWHM, since less correlated energy spread is left after the compression.

Export •

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

WEP023

Two Bunches with ns-Separation with LCLS

laser, timing, experiment, controls

634

F.-J. Decker, S. Gilevich, Z. Huang, H. Loos, A. Marinelli, C.A. Stan, J.L. Turner, Z. Van Hoover, S. Vetter
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) delivers typically one bunch. Two bunches are interesting for pump / probe experiments. Two electron bunches with ps separation have been already produced using a split and delay in the laser which produces them on the gun cathode. Here we present the combination of two lasers with a combiner, this allows any time separation and is it limited to RF bucket spacing so far to about 40 ns limited by the setup of our beam containment system. Different beam energies were also provided and the most challenging part was a transverse separation of a few σs for the two beams. Although this setup was very jittery a successful user experiment was accomplished.

Export •

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

WEP025

Effect of Microbunching on Seeding Schemes for LCLS-II

laser, electron, undulator, radiation

639

G. Penn, J. Qiang
LBNL, Berkeley, California, USA
P. Emma, E. Hemsing, Z. Huang, G. Marcus, T.O. Raubenheimer, L. Wang
SLAC, Menlo Park, 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.
External seeding and self-seeding schemes are particularly sensitive to distortions and fluctuations in the electron beam profile. Wakefields and the microbunching instability are important sources of such imperfections. Even at modest levels, their influence can degrade the spectrum and decrease the output brightness. These effects are evaluated for seeded FELs at the soft X-ray beam line of LCLS-II. FEL simulations are performed in GENESIS based on various realistic electron distributions obtained using the IMPACT tracking code. The sensitivity depends on both the seeding scheme and the output wavelength.

Poster WEP025 [0.962 MB]

Export •

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

WEP052

Studies of LCLS FEL Divergence

undulator, simulation, electron, quadrupole

681

J.L. Turner, P. Baxevanis, F.-J. Decker, Y. Ding, Z. Huang, J. Krzywinski, H. Loos, G. Marcus, N.P. Norvell
SLAC, Menlo Park, California, USA

Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515
Simulations show various impacts on x-ray divergence. With the motivation to maximize intensity at the focus, these beam studies were designed to study parameter space and beam qualities impacting divergence, and therefore aperture related clipping and diffraction. With multiple simultaneous users, beam constraints increase, requiring an improving knowledge of the mechanism of impact of changing parameters. These studies have that goal in order to improve beam control.

Poster WEP052 [1.010 MB]

Export •

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

WED03

Photon Diagnostics and Photon Beamlines Installations at the European XFEL

diagnostics, beam-transport, radiation, vacuum

764

J. Grünert, B. Baranasic, J. Buck, F. Dietrich, M. Dommach, W. Freund, A. Koch, N.G. Kujala, J. Liu, S. Molodtsov, M. Planas, H. Sinn
XFEL. EU, Hamburg, Germany

The European X-ray Free-Electron-Laser (XFEL. EU) is a new a 4th generation light facility which will deliver radiation with femtosecond and sub-Ångström resolution at MHz repetition rates, and is currently under construction in the Hamburg metropolitan area in Germany. Special diagnostics [1,2] for spontaneous radiation analysis is required to tune towards the lasing condition. Once lasing is achieved, diagnostic imagers [3], online monitors [4], and the photon beam transport system [5] need to cope with extreme radiation intensities. In 2015 the installation of machine equipment in the photon area of the facility is in full swing. This contribution presents the progress on final assemblies of photon diagnostics, the installation status of these devices as well as of the beam transport system, and recent design developments for diagnostic spectrometers and temporal diagnostics.
[1] J. Grünert, XFEL. EU TR-2012-003(2012)
[2] W. Freund, XFEL. EU TN-2014-001-01(2014)
[3] A. Koch, Proc. SPIE 95121R(2015)
[4] J. Buck et al., Proc. SPIE 85040U(2012)
[5] H. Sinn et al., XFEL. EU TR-2012-006(2012)

Slides WED03 [14.557 MB]

Export •

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