FLS2018 - List of Keywords (FEL)

Paper	Title	Other Keywords	Page
MOA2PL03	Review of New Developments in Superconducting Undulator Technology at the APS	ion, undulator, storage-ring, vacuum	1
	J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, M. Kasa, I. Kesgin, Y. Shiroyanagi ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. Superconducting undulator (SCU) technology offers the possibility of enhancing the magnetic field of undulators compared to other undulator technologies. It also allows for the fabrication of circular polarizing devices in addition to the planar undulators. Work on SCUs therefore continues in the light source community. Recent developments in SCU technology will be presented.
	Slides MOA2PL03 [1.669 MB]
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MOP1WA02	The LCLS-II-HE, A High Energy Upgrade of the LCLS-II	ion, linac, SRF, cryomodule	6
	T.O. Raubenheimer SLAC, Menlo Park, California, USA
	The LCLS-II XFEL will be based on a 4 GeV CW SRF linac and will produce x-ray pulses at 1 MHz over the spectral range of 200 to 5,00 eV. The rf gun will be installed and tested in early 2018; cryomodules are being produced at Fermilab and Jefferson lab and shipped to SLAC; undulator segments are being fabricated at LBNL and measured at SLAC. In parallel, a High Energy upgrade will be described which would extend the linac to 8 GeV and increase the spectral range to 12.8 keV.
	Slides MOP1WA02 [5.000 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-MOP1WA02
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TUP1WD02	A Study on the Improved Cavity Bunch Length Monitor for FEL	ion, cavity, simulation, electron	39
	Q. Wang, X.Y. Liu, P. Lu, Q. Luo, B.G. Sun, L.L. Tang, J.H. Wei, F.F. Wu, Y.L. Yang, T.Y. Zhou, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900), NSFC (11375178, 11575181) and the Fundamental Research Funds for the Central Universities (WK2310000046) Bunch length monitors based on cavities have great potential especially for future high quality beam sources because of many advantages such as simple structure, wide application rage, and high signal-to-noise ratio (SNR). The traditional way to measure bunch length needs two cavities at least. One is reference cavity, whose function is to get the beam intensity. The other one is defined as main cavity, which is used to calculate the bunch length. There are some drawbacks. To improve performance, the mode and the cavity shape are changed. At the same time, the position and orientation of coaxial probe are designed to avoid interference modes which come from the cavity and beam tube according to the analytic formula of the electromagnetic field distribution. A series simulation based on CST is performed to verify the feasibility, and the simulation results reveal that the improved monitor shows good performance in bunch length measurement.
	Slides TUP1WD02 [3.505 MB]
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TUP1WD03	The Development and Applications of the Digital BPM Signal Processor at SINAP	ion, cavity, SRF, brilliance	43
	L.W. Lai, S.S. Cao, F.Z. Chen, Y.B. Leng, Y.B. Yan, W.M. Zhou SSRF, Shanghai, People's Republic of China J. Chen, Y.B. Leng, Y.B. Yan, W.M. Zhou SINAP, Shanghai, People's Republic of China
	BPM signal processor is one of key beam diagnostics instruments. It has been progressing from analog to digital. The current major processors are digital BPM signal processor (DBPM). Except for some commercial products on-the-shelf, several laboratories developed in-house DBPMs for their own facilities. SINAP started the DBPM development since 2009, when the SSRF phase-I has been completed. After years of optimization, the DBPM has been used in large-scale on some facilities, including SSRF, DCLS and SXFEL. At the same time, some extended functions have been developed to meet special applications on accelerator based on the hardware platform. This topic will introduce the development and applications of the DBPM at SINAP, also the future DBPM development for next generation light source will be discussed here.
	Slides TUP1WD03 [14.850 MB]
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TUA2WC02	"LWFA-driven" Free Electron Laser for ELI-Beamlines	ion, electron, undulator, photon	62
	A.Y. Molodozhentsev, G. Korn, L. Pribyl Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic A.R. Maier University of Hamburg, Hamburg, Germany
	Free-electron lasers (FEL) are unique light source for different applications on the femto-second scale, including for instance the most basic reaction mechanisms in chemistry, structural biology and condense physics. Laser wake field acceleration (LWFA) mechanism allow to produce extremely short electron bunches of a few fs length with the energy up to a few GeV providing peak current of many kA in extremely compact geometries. This novel acceleration method therefore opens a new way to develop compact "laser-based" FELs. ELI beamlines is an international user facility for fundamental and applied research using ultra-intense lasers and ultra-short high-energy electron beams. In frame of this report we present conceptual solutions for an compact "LFWA" based soft X-ray FEL, which can deliver a photon peak brightness of 10³¹ ph/sec/mm²/mrad²/0.1%bw. A combination of this achievement with novel laser technologies will open a new perspective for the development of extremely compact FELs with few or even sub-femtosecond photon bunches for a very wide user community.
	Slides TUA2WC02 [3.882 MB]
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TUP2WA03	Harmonic Lasing in X-Ray FELs: Theory and Experiment	ion, undulator, electron, radiation	68
	E. Schneidmiller, B. Faatz, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, M. Tischer, M.V. Yurkov DESY, Hamburg, Germany
	Harmonic lasing in XFELs is an opportunity to extend operating range of existing and planned X-ray FEL user facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental. Another interesting application of harmonic lasing is Harmonic Lasing Self-Seeded (HLSS) FEL, that allows to improve longitudinal coherence and spectral power of a SASE FEL. Recently* this concept was successfully tested at FLASH2 in the range 4.5 - 15 nm. That was also the first experimental demonstration of harmonic lasing in a high-gain FEL and at a short wavelength (before it worked only in infrared FEL oscillators). In this contribution we describe the concepts of harmonic lasing and of HLSS FEL, and present the experimental results from FLASH2. * E.Schneidmiller and M.Yurkov, Phys. Rev. ST-AB 15(2012)080702 E.Schneidmiller and M.Yurkov, Proc. of FEL2013, p.700 * E.Schneidmiller et al., Phys. Rev. Accel. Beams 20(2017)020705
	Slides TUP2WA03 [3.378 MB]
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WEA1PL03	Attosecond Timing	ion, laser, timing, electron	79
	F.X. Kärtner Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany K. Shafak CFEL, Hamburg, Germany K. Shafak Cycle GmbH, Hamburg, Germany M. Xin DESY, Hamburg, Germany
	Funding: This work was supported by DESY and the European Research Council under the European Union's Seventh Framework Program (FP/2007-2013) / ERC Grant Agreement No. 609920. Photon-science facilities such as X-ray free-electron lasers (XFELs) and intense-laser facilities are emerging world-wide with some of them producing sub-fs X-ray pulses. These facilities are in need of a high-precision timing distribution system, which can synchronize various microwave and optical sub-sources across multi-km distances with attosecond precision. Here, we report on a synchronous laser-microwave network that permits attosecond precision across km-scale distances. This was achieved by developing new ultrafast timing metrology devices and carefully balancing the fiber nonlinearities and fundamental noise contributions in the system. New polarization-noise-suppressed balanced optical crosscorrelators and free-space-coupled balanced optical-microwave phase detectors for improved noise performance have been implemented. Residual second- and third-order dispersion in the fiber links are carefully compensated with additional dispersion-compensating fiber to suppress link-induced Gordon-Haus jitter and to minimize output pulse duration; the link power is stabilized to minimize the nonlinearity-induced jitter as well as to maximize the signal to noise ratio for locking.
	Slides WEA1PL03 [5.888 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEA1PL03
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WEP1WC02	CompactLight Design Study	ion, undulator, electron, gun	85
	A. Latina, D. Schulte, S. Stapnes, W. Wuensch CERN, Geneva, Switzerland M. Aicheler HIP, University of Helsinki, Finland A.A. Aksoy Ankara University Institute of Accelerator Technologies, Golbasi, Turkey A. Bernhard KIT, Karlsruhe, Germany J.A. Clarke STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A.W. Cross USTRAT/SUPA, Glasgow, United Kingdom G. D'Auria, R. Geometrante Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy R.T. Dowd AS - ANSTO, Clayton, Australia D. Esperante Pereira IFIC, Valencia, Spain W. Fang SINAP, Shanghai, People's Republic of China A. Faus-Golfe LAL, Orsay, France M. Ferrario INFN/LNF, Frascati (Roma), Italy E.N. Gazis National Technical University of Athens, Athens, Greece R. Geometrante KYMA, Trieste, Italy M. Jacewicz Uppsala University, Uppsala, Sweden A. Mostacci Sapienza University of Rome, Rome, Italy F. Nguyen ENEA C.R. Frascati, Frascati (Roma), Italy F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain J.M.A. Priem VDL ETG, Eindhoven, The Netherlands T. Schmidt PSI, Villigen PSI, Switzerland
	H2020 CompactLight Project aims at designing the next generation of compact hard X-Rays Free-Electron Lasers, relying on very high accelerating gradients and on novel undulator concepts. CompactLight intends to design a compact Hard X-ray FEL facility based on very high-gradient acceleration in the X band of frequencies, on a very bright photo injector, and on short-period/superconductive undulators to enable smaller electron beam energy. If compared to existing facilities, the proposed facility will benefit from a lower electron beam energy, due to the enhanced undulators performance, be significantly more compact, as a consequence both of the lower energy and of the high-gradient X-band structures, have lower electrical power demand and a smaller footprint. CompactLight is a consortium of 24 institutes (21 European + 3 extra Europeans), gathering the world-leading experts both in the domains of X-band acceleration and undulator design.
	Slides WEP1WC02 [12.831 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEP1WC02
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WEA2WD03	Analysis of Electron Trajectories in Harmonic Undulator with SCILAB's Model Based Design Codes	ion, undulator, simulation, electron	93
	H. Jeevakhan, S. Kumar NITTTR, Bhopal, India G. Mishra Devi Ahilya University, Indore, India
	Scilab's X-cos model-based simulation blocks has been used to simulate the trajectories of an electron traversing through an Harmonic undulator. The trajectory of electron along X and Y directions has been simulated from Numerical and analytical methods. Analysis given in the present paper is compared with the other codes. Parallel simulation of Harmonic undulator magnetic field along with trajectories of electron is given in the present analysis.
	Slides WEA2WD03 [0.652 MB]
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WEA2WD04	Harmonic Undulator Radiation with Dual Non Periodic Magnetic Components	ion, undulator, electron, radiation	98
	H. Jeevakhan NITTTR, Bhopal, India G. Mishra Devi Ahilya University, Indore, India
	Undulator radiation at third harmonics generated by harmonic undulator in the presence dual non periodic constant magnetic field. Electron trajectories along the x and y direction has been determined analytical and numerical methods. Generalized Bessel function is used to determine the intensity of radiation and Simpson's numerical method of integration is used to find the effect of constant magnetic fields. Comparison with previous analysis has also been presented.
	Slides WEA2WD04 [1.050 MB]
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WEP2PT003	Undulator Phase Matching for the the European XFEL	ion, undulator, electron, radiation	103
	Y. Li, J. Pflüger XFEL. EU, Hamburg, Germany
	The undulator system in the European XFEL is mainly comprised 5-m long undulator segments and 1.1 m long intersections in between. In intersections the electron velocity is faster than it inside an undulator and the optical phase is detuned. The detune effect is also from the undulator fringe field where electron longitudinal speed also deviates from the oscillation condition. The total detune effect is compensated by a magnetic device called phase shifter, which is correspondingly set for a specific undulator gap. In this paper we introduce the method to set the phase shifter gap for each K parameter according to the measured magnetic field.
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WEP2PT008	Microbunching Instability Study in the Linac-Driven FERMI FEL Spreader Beam Line	ion, linac, laser, electron	108
	S. Di Mitri, S. Spampinati Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	Suppression of microbunching instability (MBI) along high brightness electron beam delivery systems is a priority for Free Electron lasers (FELs) aiming at very narrow bandwidth. The impact of MBI on FEL spectral brilliance is aggravated by the growing demand for multi-user FEL facilities, which adopt multi-bend switchyard lines traversed by high charge density electron beams. This study provides practical guidelines to switchyards design largely immune to MBI, by focusing on the FERMI FEL Spreader line. First, two MBI analytical models [1, 2] are successfully benchmarked along the accelerator. Being the second model flexible enough to describe an arbitrary multi-bend line, and found it in agreement with particle tracking and experimental results, it was used to demonstrate that a newly proposed Spreader optics provides unitary MBI gain while preserving the electron beam brightness. [1] Z. Huang and K.-J. Kim, Phys. Rev. Special Topics - Accel. Beams 5, 074401 (2002) [2] R.A. Bosch, K.J. Kleman, and J. Wu, Phys. Rev. Special Topics - Accel. Beams 11, 090702 (2008)
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WEP2PT033	Conceptual Design of Superconducting Transverse Gradient Undulator for PAL-XFEL Beamline	ion, undulator, operation, electron	142
	S.J. Lee, J.H. Han PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT \& Future Planning(2017R1C1B1012852) Recently, the transverse gradient undulator (TGU) applications are suggested from the laser plasma wake-field accelerator (LPWA) to ultimate storage ring (USR). Especially for X-ray FEL, TGU can be used to generate the large bandwidth radiation (up to §I10{\percent}). In this proceeding, the review of PAL-XFEL beam parameters and TGU requirements was done to apply a variable large bandwidth operation to the PAL-XFEL beamlines. Also, the conceptual design of TGU, based on superconducting undulator (SCU) was proposed, and B-field calculation results were introduced for PAL-XFEL large bandwidth operation mode.
	Poster WEP2PT033 [0.927 MB]
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WEP2PT050	Status of CAEP THz Free Electron Laser Oscillator	ion, electron, laser, free-electron-laser	154
	M. Li, T.H. He, C.L. Lao, P. Li, S.F. Lin, X. Luo, Q. Pan, L.J. Shan, X. Shen, H. Wang, J. Wang, D. Wu, D.X. Xiao, Y. Xu, X. Yang, P. Zhang, K. Zhou CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	China Academy of Engineering Physics tera-hertz free electron laser (CAEP THz FEL, CTFEL) is the first THz FEL oscillator in China, which was jointly built by CAEP, Peking university and Tsinghua university. The stimulated saturation of the CTFEL was reached in August, 2017. This THz FEL facility consists of a GaAs photocathode high-voltage DC gun, a superconducting RF linac, a planar undulator and a quasi-concentric optical resonator. The terahertz laser's frequency is continuous adjustable from 2 THz to 3 THz. The average power is more than 10 W and the micro-pulse power is more than 0.1 MW.
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THA1WC01	Compact Arc Compressor for FEL-Driven Compton Light Source and ERL-Driven UV FEL	ion, emittance, electron, dipole	183
	S. Di Mitri Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy J.A.G. Akkermans, I. Setija ASML Netherlands B.V., Veldhoven, The Netherlands D. Douglas JLab, Newport News, Virginia, USA C. Pellegrini SLAC, Menlo Park, California, USA G. Penn, M. Placidi LBNL, Berkeley, California, USA
	Many research and applications areas require photon sources capable of producing extreme ultra-violet (EUV) to gamma-ray beams with reasonably high fluxes and compact footprints. We explore the feasibility of a compact energy-recovery linac EUV free electron laser (FEL), and of a multi-MeV gamma-rays source based on inverse Compton scattering from a high intensity UV FEL emitted by the electron beam itself. In the latter scenario, the same electron beam is used to produce gamma-rays in the 10-20 MeV range and UV radiation in the 10¹⁵ eV range, in a ~4x22 m² footprint system.* * J.Akkermans, S.Di Mitri, D.Douglas, I.Setija, PRAB 20, 080705 (2017). ** M. Placidi, S. Di Mitri,⁎, C. Pellegrini, G. Penn, NIM A 855 (2017) 55-60.
	Slides THA1WC01 [5.258 MB]
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THP1WD02	LCLS-II Beam Containment System for Radiation Safety	ion, electron, cavity, radiation	187
	C.I. Clarke, J. Bauer, M. Boyes, Y. Feng, A.S. Fisher, R.A. Kadyrov, J.C. Liu, E. Rodriguez, M. Rowen, M. Santana-Leitner, F. Tao, J.J. Welch, S. Xiao SLAC, Menlo Park, California, USA T.L. Allison, J. Musson JLab, Newport News, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515 and DE-AC05-06OR23177. LCLS-II is a new xFEL facility under construction at SLAC National Accelerator Laboratory with a superconducting electron linac designed to operate up to §I{1.2}{MW} of beam power. This generates more serious beam hazards than the typical sub-kW linac operation of the existing xFEL facility, Linac Coherent Light Source (LCLS). SLAC uses a set of safety controls termed the Beam Containment System (BCS) to limit beam power and losses to prevent excessive radiation in occupied areas. The high beam power hazards of LCLS-II necessitate the development of new BCS devices and a larger scale deployment than previously done at LCLS. We present the new radiation hazards introduced by LCLS-II and the design development for the BCS.
	Slides THP1WD02 [2.244 MB]
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FRA1PL01	Summary Report: Linac-Based Light Sources	ion, experiment, simulation, linac	199
	T.O. Raubenheimer SLAC, Menlo Park, California, USA W. Decking DESY, Hamburg, Germany L. Giannessi Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy L. Giannessi ENEA C.R. Frascati, Frascati (Roma), Italy H.-S. Kang PAL, Pohang, Kyungbuk, Republic of Korea
	This is the summary report of the linac-based light sources working group.
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Paper

Title

Other Keywords

Page

MOA2PL03

Review of New Developments in Superconducting Undulator Technology at the APS

ion, undulator, storage-ring, vacuum

1

J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, M. Kasa, I. Kesgin, Y. Shiroyanagi
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Superconducting undulator (SCU) technology offers the possibility of enhancing the magnetic field of undulators compared to other undulator technologies. It also allows for the fabrication of circular polarizing devices in addition to the planar undulators. Work on SCUs therefore continues in the light source community. Recent developments in SCU technology will be presented.

Slides MOA2PL03 [1.669 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-MOA2PL03

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MOP1WA02

The LCLS-II-HE, A High Energy Upgrade of the LCLS-II

ion, linac, SRF, cryomodule

6

T.O. Raubenheimer
SLAC, Menlo Park, California, USA

The LCLS-II XFEL will be based on a 4 GeV CW SRF linac and will produce x-ray pulses at 1 MHz over the spectral range of 200 to 5,00 eV. The rf gun will be installed and tested in early 2018; cryomodules are being produced at Fermilab and Jefferson lab and shipped to SLAC; undulator segments are being fabricated at LBNL and measured at SLAC. In parallel, a High Energy upgrade will be described which would extend the linac to 8 GeV and increase the spectral range to 12.8 keV.

Slides MOP1WA02 [5.000 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-MOP1WA02

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TUP1WD02

A Study on the Improved Cavity Bunch Length Monitor for FEL

ion, cavity, simulation, electron

39

Q. Wang, X.Y. Liu, P. Lu, Q. Luo, B.G. Sun, L.L. Tang, J.H. Wei, F.F. Wu, Y.L. Yang, T.Y. Zhou, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900), NSFC (11375178, 11575181) and the Fundamental Research Funds for the Central Universities (WK2310000046)
Bunch length monitors based on cavities have great potential especially for future high quality beam sources because of many advantages such as simple structure, wide application rage, and high signal-to-noise ratio (SNR). The traditional way to measure bunch length needs two cavities at least. One is reference cavity, whose function is to get the beam intensity. The other one is defined as main cavity, which is used to calculate the bunch length. There are some drawbacks. To improve performance, the mode and the cavity shape are changed. At the same time, the position and orientation of coaxial probe are designed to avoid interference modes which come from the cavity and beam tube according to the analytic formula of the electromagnetic field distribution. A series simulation based on CST is performed to verify the feasibility, and the simulation results reveal that the improved monitor shows good performance in bunch length measurement.

Slides TUP1WD02 [3.505 MB]

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TUP1WD03

The Development and Applications of the Digital BPM Signal Processor at SINAP

ion, cavity, SRF, brilliance

43

L.W. Lai, S.S. Cao, F.Z. Chen, Y.B. Leng, Y.B. Yan, W.M. Zhou
SSRF, Shanghai, People's Republic of China
J. Chen, Y.B. Leng, Y.B. Yan, W.M. Zhou
SINAP, Shanghai, People's Republic of China

BPM signal processor is one of key beam diagnostics instruments. It has been progressing from analog to digital. The current major processors are digital BPM signal processor (DBPM). Except for some commercial products on-the-shelf, several laboratories developed in-house DBPMs for their own facilities. SINAP started the DBPM development since 2009, when the SSRF phase-I has been completed. After years of optimization, the DBPM has been used in large-scale on some facilities, including SSRF, DCLS and SXFEL. At the same time, some extended functions have been developed to meet special applications on accelerator based on the hardware platform. This topic will introduce the development and applications of the DBPM at SINAP, also the future DBPM development for next generation light source will be discussed here.

Slides TUP1WD03 [14.850 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUP1WD03

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TUA2WC02

"LWFA-driven" Free Electron Laser for ELI-Beamlines

ion, electron, undulator, photon

62

A.Y. Molodozhentsev, G. Korn, L. Pribyl
Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic
A.R. Maier
University of Hamburg, Hamburg, Germany

Free-electron lasers (FEL) are unique light source for different applications on the femto-second scale, including for instance the most basic reaction mechanisms in chemistry, structural biology and condense physics. Laser wake field acceleration (LWFA) mechanism allow to produce extremely short electron bunches of a few fs length with the energy up to a few GeV providing peak current of many kA in extremely compact geometries. This novel acceleration method therefore opens a new way to develop compact "laser-based" FELs. ELI beamlines is an international user facility for fundamental and applied research using ultra-intense lasers and ultra-short high-energy electron beams. In frame of this report we present conceptual solutions for an compact "LFWA" based soft X-ray FEL, which can deliver a photon peak brightness of 10³¹ ph/sec/mm²/mrad²/0.1%bw. A combination of this achievement with novel laser technologies will open a new perspective for the development of extremely compact FELs with few or even sub-femtosecond photon bunches for a very wide user community.

Slides TUA2WC02 [3.882 MB]

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TUP2WA03

Harmonic Lasing in X-Ray FELs: Theory and Experiment

ion, undulator, electron, radiation

68

E. Schneidmiller, B. Faatz, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, M. Tischer, M.V. Yurkov
DESY, Hamburg, Germany

Harmonic lasing in XFELs is an opportunity to extend operating range of existing and planned X-ray FEL user facilities*. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental. Another interesting application of harmonic lasing is Harmonic Lasing Self-Seeded (HLSS) FEL*,** that allows to improve longitudinal coherence and spectral power of a SASE FEL. Recently*** this concept was successfully tested at FLASH2 in the range 4.5 - 15 nm. That was also the first experimental demonstration of harmonic lasing in a high-gain FEL and at a short wavelength (before it worked only in infrared FEL oscillators). In this contribution we describe the concepts of harmonic lasing and of HLSS FEL, and present the experimental results from FLASH2.
* E.Schneidmiller and M.Yurkov, Phys. Rev. ST-AB 15(2012)080702
** E.Schneidmiller and M.Yurkov, Proc. of FEL2013, p.700
*** E.Schneidmiller et al., Phys. Rev. Accel. Beams 20(2017)020705

Slides TUP2WA03 [3.378 MB]

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WEA1PL03

Attosecond Timing

ion, laser, timing, electron

79

F.X. Kärtner
Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
K. Shafak
CFEL, Hamburg, Germany
K. Shafak
Cycle GmbH, Hamburg, Germany
M. Xin
DESY, Hamburg, Germany

Funding: This work was supported by DESY and the European Research Council under the European Union's Seventh Framework Program (FP/2007-2013) / ERC Grant Agreement No. 609920.
Photon-science facilities such as X-ray free-electron lasers (XFELs) and intense-laser facilities are emerging world-wide with some of them producing sub-fs X-ray pulses. These facilities are in need of a high-precision timing distribution system, which can synchronize various microwave and optical sub-sources across multi-km distances with attosecond precision. Here, we report on a synchronous laser-microwave network that permits attosecond precision across km-scale distances. This was achieved by developing new ultrafast timing metrology devices and carefully balancing the fiber nonlinearities and fundamental noise contributions in the system. New polarization-noise-suppressed balanced optical crosscorrelators and free-space-coupled balanced optical-microwave phase detectors for improved noise performance have been implemented. Residual second- and third-order dispersion in the fiber links are carefully compensated with additional dispersion-compensating fiber to suppress link-induced Gordon-Haus jitter and to minimize output pulse duration; the link power is stabilized to minimize the nonlinearity-induced jitter as well as to maximize the signal to noise ratio for locking.

Slides WEA1PL03 [5.888 MB]

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WEP1WC02

CompactLight Design Study

ion, undulator, electron, gun

85

A. Latina, D. Schulte, S. Stapnes, W. Wuensch
CERN, Geneva, Switzerland
M. Aicheler
HIP, University of Helsinki, Finland
A.A. Aksoy
Ankara University Institute of Accelerator Technologies, Golbasi, Turkey
A. Bernhard
KIT, Karlsruhe, Germany
J.A. Clarke
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.W. Cross
USTRAT/SUPA, Glasgow, United Kingdom
G. D'Auria, R. Geometrante
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
R.T. Dowd
AS - ANSTO, Clayton, Australia
D. Esperante Pereira
IFIC, Valencia, Spain
W. Fang
SINAP, Shanghai, People's Republic of China
A. Faus-Golfe
LAL, Orsay, France
M. Ferrario
INFN/LNF, Frascati (Roma), Italy
E.N. Gazis
National Technical University of Athens, Athens, Greece
R. Geometrante
KYMA, Trieste, Italy
M. Jacewicz
Uppsala University, Uppsala, Sweden
A. Mostacci
Sapienza University of Rome, Rome, Italy
F. Nguyen
ENEA C.R. Frascati, Frascati (Roma), Italy
F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
J.M.A. Priem
VDL ETG, Eindhoven, The Netherlands
T. Schmidt
PSI, Villigen PSI, Switzerland

H2020 CompactLight Project aims at designing the next generation of compact hard X-Rays Free-Electron Lasers, relying on very high accelerating gradients and on novel undulator concepts. CompactLight intends to design a compact Hard X-ray FEL facility based on very high-gradient acceleration in the X band of frequencies, on a very bright photo injector, and on short-period/superconductive undulators to enable smaller electron beam energy. If compared to existing facilities, the proposed facility will benefit from a lower electron beam energy, due to the enhanced undulators performance, be significantly more compact, as a consequence both of the lower energy and of the high-gradient X-band structures, have lower electrical power demand and a smaller footprint. CompactLight is a consortium of 24 institutes (21 European + 3 extra Europeans), gathering the world-leading experts both in the domains of X-band acceleration and undulator design.

Slides WEP1WC02 [12.831 MB]

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WEA2WD03

Analysis of Electron Trajectories in Harmonic Undulator with SCILAB's Model Based Design Codes

ion, undulator, simulation, electron

93

H. Jeevakhan, S. Kumar
NITTTR, Bhopal, India
G. Mishra
Devi Ahilya University, Indore, India

Scilab's X-cos model-based simulation blocks has been used to simulate the trajectories of an electron traversing through an Harmonic undulator. The trajectory of electron along X and Y directions has been simulated from Numerical and analytical methods. Analysis given in the present paper is compared with the other codes. Parallel simulation of Harmonic undulator magnetic field along with trajectories of electron is given in the present analysis.

Slides WEA2WD03 [0.652 MB]

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WEA2WD04

Harmonic Undulator Radiation with Dual Non Periodic Magnetic Components

ion, undulator, electron, radiation

98

H. Jeevakhan
NITTTR, Bhopal, India
G. Mishra
Devi Ahilya University, Indore, India

Undulator radiation at third harmonics generated by harmonic undulator in the presence dual non periodic constant magnetic field. Electron trajectories along the x and y direction has been determined analytical and numerical methods. Generalized Bessel function is used to determine the intensity of radiation and Simpson's numerical method of integration is used to find the effect of constant magnetic fields. Comparison with previous analysis has also been presented.

Slides WEA2WD04 [1.050 MB]

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WEP2PT003

Undulator Phase Matching for the the European XFEL

ion, undulator, electron, radiation

103

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

The undulator system in the European XFEL is mainly comprised 5-m long undulator segments and 1.1 m long intersections in between. In intersections the electron velocity is faster than it inside an undulator and the optical phase is detuned. The detune effect is also from the undulator fringe field where electron longitudinal speed also deviates from the oscillation condition. The total detune effect is compensated by a magnetic device called phase shifter, which is correspondingly set for a specific undulator gap. In this paper we introduce the method to set the phase shifter gap for each K parameter according to the measured magnetic field.

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WEP2PT008

Microbunching Instability Study in the Linac-Driven FERMI FEL Spreader Beam Line

ion, linac, laser, electron

108

S. Di Mitri, S. Spampinati
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Suppression of microbunching instability (MBI) along high brightness electron beam delivery systems is a priority for Free Electron lasers (FELs) aiming at very narrow bandwidth. The impact of MBI on FEL spectral brilliance is aggravated by the growing demand for multi-user FEL facilities, which adopt multi-bend switchyard lines traversed by high charge density electron beams. This study provides practical guidelines to switchyards design largely immune to MBI, by focusing on the FERMI FEL Spreader line. First, two MBI analytical models [1, 2] are successfully benchmarked along the accelerator. Being the second model flexible enough to describe an arbitrary multi-bend line, and found it in agreement with particle tracking and experimental results, it was used to demonstrate that a newly proposed Spreader optics provides unitary MBI gain while preserving the electron beam brightness.
[1] Z. Huang and K.-J. Kim, Phys. Rev. Special Topics - Accel. Beams 5, 074401 (2002)
[2] R.A. Bosch, K.J. Kleman, and J. Wu, Phys. Rev. Special Topics - Accel. Beams 11, 090702 (2008)

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WEP2PT033

Conceptual Design of Superconducting Transverse Gradient Undulator for PAL-XFEL Beamline

ion, undulator, operation, electron

142

S.J. Lee, J.H. Han
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT \& Future Planning(2017R1C1B1012852)
Recently, the transverse gradient undulator (TGU) applications are suggested from the laser plasma wake-field accelerator (LPWA) to ultimate storage ring (USR). Especially for X-ray FEL, TGU can be used to generate the large bandwidth radiation (up to §I10{\percent}). In this proceeding, the review of PAL-XFEL beam parameters and TGU requirements was done to apply a variable large bandwidth operation to the PAL-XFEL beamlines. Also, the conceptual design of TGU, based on superconducting undulator (SCU) was proposed, and B-field calculation results were introduced for PAL-XFEL large bandwidth operation mode.

Poster WEP2PT033 [0.927 MB]

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WEP2PT050

Status of CAEP THz Free Electron Laser Oscillator

ion, electron, laser, free-electron-laser

154

M. Li, T.H. He, C.L. Lao, P. Li, S.F. Lin, X. Luo, Q. Pan, L.J. Shan, X. Shen, H. Wang, J. Wang, D. Wu, D.X. Xiao, Y. Xu, X. Yang, P. Zhang, K. Zhou
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

China Academy of Engineering Physics tera-hertz free electron laser (CAEP THz FEL, CTFEL) is the first THz FEL oscillator in China, which was jointly built by CAEP, Peking university and Tsinghua university. The stimulated saturation of the CTFEL was reached in August, 2017. This THz FEL facility consists of a GaAs photocathode high-voltage DC gun, a superconducting RF linac, a planar undulator and a quasi-concentric optical resonator. The terahertz laser's frequency is continuous adjustable from 2 THz to 3 THz. The average power is more than 10 W and the micro-pulse power is more than 0.1 MW.

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THA1WC01

Compact Arc Compressor for FEL-Driven Compton Light Source and ERL-Driven UV FEL

ion, emittance, electron, dipole

183

S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
J.A.G. Akkermans, I. Setija
ASML Netherlands B.V., Veldhoven, The Netherlands
D. Douglas
JLab, Newport News, Virginia, USA
C. Pellegrini
SLAC, Menlo Park, California, USA
G. Penn, M. Placidi
LBNL, Berkeley, California, USA

Many research and applications areas require photon sources capable of producing extreme ultra-violet (EUV) to gamma-ray beams with reasonably high fluxes and compact footprints. We explore the feasibility of a compact energy-recovery linac EUV free electron laser (FEL)*, and of a multi-MeV gamma-rays source based on inverse Compton scattering from a high intensity UV FEL emitted by the electron beam itself. In the latter scenario, the same electron beam is used to produce gamma-rays in the 10-20 MeV range and UV radiation in the 10¹⁵ eV range, in a ~4x22 m² footprint system.**
* J.Akkermans, S.Di Mitri, D.Douglas, I.Setija, PRAB 20, 080705 (2017).
** M. Placidi, S. Di Mitri,⁎, C. Pellegrini, G. Penn, NIM A 855 (2017) 55-60.

Slides THA1WC01 [5.258 MB]

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THP1WD02

LCLS-II Beam Containment System for Radiation Safety

ion, electron, cavity, radiation

187

C.I. Clarke, J. Bauer, M. Boyes, Y. Feng, A.S. Fisher, R.A. Kadyrov, J.C. Liu, E. Rodriguez, M. Rowen, M. Santana-Leitner, F. Tao, J.J. Welch, S. Xiao
SLAC, Menlo Park, California, USA
T.L. Allison, J. Musson
JLab, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515 and DE-AC05-06OR23177.
LCLS-II is a new xFEL facility under construction at SLAC National Accelerator Laboratory with a superconducting electron linac designed to operate up to §I{1.2}{MW} of beam power. This generates more serious beam hazards than the typical sub-kW linac operation of the existing xFEL facility, Linac Coherent Light Source (LCLS). SLAC uses a set of safety controls termed the Beam Containment System (BCS) to limit beam power and losses to prevent excessive radiation in occupied areas. The high beam power hazards of LCLS-II necessitate the development of new BCS devices and a larger scale deployment than previously done at LCLS. We present the new radiation hazards introduced by LCLS-II and the design development for the BCS.

Slides THP1WD02 [2.244 MB]

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FRA1PL01

Summary Report: Linac-Based Light Sources

ion, experiment, simulation, linac

199

T.O. Raubenheimer
SLAC, Menlo Park, California, USA
W. Decking
DESY, Hamburg, Germany
L. Giannessi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
H.-S. Kang
PAL, Pohang, Kyungbuk, Republic of Korea

This is the summary report of the linac-based light sources working group.

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