LINAC2018 - Classification: Electron Accelerators and Applications / FELs

Paper	Title	Page
MO2A01	XFEL Projects in China
	Z.T. Zhao, D. Wang SINAP, Shanghai, People’s Republic of China
	840MeV SXFEL is the first soft X-ray FEL built in Shanghai, now it’s in the commissiong stage. Also in Shanghai light source, a Hard X-ray 8GeV CW FEL has been proposed many years ago, and presumably will be approved in 2018.
	Slides MO2A01 [19.783 MB]
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MO2A02	Linac Based Light Source Activities at THU
	Y. C. Du, L.X. Yan TUB, Beijing, People’s Republic of China
	The high brightness electron linac based on a photocathode RF gun was established in Tsinghua University for the study of Thomson scattering x-ray and THz radiation light sources. Recent THz radiation research activities with tunable bunch trains, specially on their generation and diagnostics, will be presented. Experiments on coherent undulator radiation, coherent transition radiation, coherent Smith-Purcell radiation, dielectric wakefield radiation were performed. Another part of this talk will be focused on the recent progress in linac based ICS source at Tsinghua University, including the experiments on X/gamma-ray generation, diagnostic, and its applications in advanced X-ray imaging. And the design of a new compact ICS gamma-ray sources will also be discussed in this talk.
	Slides MO2A02 [12.656 MB]
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MO2A04	Compact SRF Linac for High Brilliance Inverse Compton Scattering Light Source	19
	K.E. Deitrick, J.R. Delayen, G.A. Krafft, B. Terzić ODU, Norfolk, Virginia, USA J.R. Delayen, G.A. Krafft JLab, Newport News, Virginia, USA
	New designs for compact SRF linacs can produce micron-size electron beams. These can can be used for inverse Compton scattering light sources of exceptional flux and brilliance.
	Slides MO2A04 [1.717 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO2A04
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO034	Dielectric Waveguide-Based THz Radiator Study for SwissFEL	94
MOOP06	use link to see paper's listing under its alternate paper code
	L. Shi, S. Bettoni, M.M. Dehler, E. Ferrari, B. Hermann, R. Ischebeck, F. Marcellini, S. Reiche, V.G. Thominet PSI, Villigen PSI, Switzerland A.K. Mittelbach Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany
	Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 701647 THz pulses have many unique properties in terms of radiation matter interaction. In particular their non-ionizing excitation of phonons in matter makes them a preferred pump for pump-probe studies at free electron lasers. In order to enrich the scientific potentials at SwissFEL (Swiss Free Electron Laser), which can provide ultrashort soft and hard X-ray pulses, we plan to build an economic THz radiator in the range of 1-20 THz by passing the spent electron beam through a dielectric lined tube after the electron beam has generated X-rays. These THz pulses will be transported to the photon user station. Since SwissFEL operates with 2 bunches, serving two beamlines, THz from the first bunch can be used at the user station of the second bunch to allow for pump arrival time before the probe. The core of such a THz generation setup is the dielectric lined tube and the relativistic electron beam. This paper reports on the numerical study of these tubes, in terms of mode structure, energy, pulse length etc, which are essential parameters for the pump-probe experiments. These tubes will be fabricated and tested in the near future in the electron beam line for the soft X-ray of SwissFEL.
	Slides MOPO034 [1.471 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO034
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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MOPO035	Status of CLARA Front End Commissioning	98
MOOP03	use link to see paper's listing under its alternate paper code
	D. Angal-Kalinin, A.D. Brynes, S.R. Buckley, P.A. Corlett, L.S. Cowie, K.D. Dumbell, D.J. Dunning, P.C. Hornickel, F. Jackson, J.K. Jones, J.W. McKenzie, B.L. Militsyn, A.J. Moss, T.C.Q. Noakes, M.D. Roper, D.J. Scott, B.J.A. Shepherd, E.W. Snedden, N. Thompson, C. Tollervey, D.A. Walsh, T.M. Weston, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.J. Cash, R.F. Clarke, G. Cox, C. Hodgkinson, R.J. Smith, J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom K.D. Dumbell, B.J.A. Shepherd Cockcroft Institute, Warrington, Cheshire, United Kingdom
	CLARA (Compact Linear Accelerator for Research and Applications) is a Free Electron Laser (FEL) test facility under development at Daresbury Laboratory. The principal aim of CLARA is to test advanced FEL schemes which can later be implemented on existing and future short wavelength FELs. We report on the commissioning of the CLARA front end, consisting of a photoinjector and the first linac section, and merger into the existing VELA (Versatile Electron Linear Accelerator) beamline.
	Slides MOPO035 [1.870 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO035
About •	paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO036	Status of the 10 MW MBKs during Commissioning of the European XFEL in DESY	102
MOOP04	use link to see paper's listing under its alternate paper code
	V. Vogel (Fogel), Ł. Butkowski, A. Cherepenko, S. Choroba, J. Hartung DESY, Hamburg, Germany
	At present 26 RF stations for European XFEL are in operation. Each of the RF stations consists of a HV modulator located in a separate building on the DESY campus, up to 1600 m long 10 kV HV cables that connect the modulator and the HV pulse transformer located in the underground tunnel, 120kV, 3 m long HV cable connecting the HV pulse transformer and the connection module of the horizontal multi-beam klystron. Two RF stations of the injector have already achieved about 20000 hours of operation, RF stations of the XFEL bunch compressor area have operated up to 11000 hours and in the XFEL main linac up to 8000 hours. To increase the lifetime of the klystrons, we use a fast protection system (KLM) that is based on the comparison of the actual RF shape and the expected RF shape. In the case of a difference exceeding a certain margin, for example, in the case of RF breakdown in a klystron or RF breakdown in a waveguide system, the KLM quickly, shorter than 500 ns, switches off the input RF signal. Thus, it does prevents the vacuum level in the klystron worsen too much or it minimizes the RF overvoltage time at the output windows of the klystron in case of breakdown in waveguides.
	Slides MOPO036 [5.241 MB]
	Poster MOPO036 [0.658 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO036
About •	paper received ※ 05 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO037	SRF Gun Development at DESY	105
MOOP07	use link to see paper's listing under its alternate paper code
	E. Vogel, S. Barbanotti, I. Hartl, K. Jensch, D. Klinke, D. Kostin, W.-D. Möller, M. Schmökel, J.K. Sekutowicz, S. Sievers, N. Steinhau-Kühl, A.A. Sulimov, J.H. Thie, H. Weise, L. Winkelmann, B. van der Horst DESY, Hamburg, Germany J.A. Lorkiewicz, R. Nietubyć NCBJ, Świerk/Otwock, Poland J. Smedley BNL, Upton, Long Island, New York, USA J. Teichert HZDR, Dresden, Germany M. Wiencek IFJ-PAN, Kraków, Poland
	A future upgrade of the European XFEL (E-XFEL) foresees an additional cw operation mode increasing the flexibility in the photon beam time structure. This mode requires among others a cw operating photo injector. We believe that using an SRF gun is the preferred approach as the beam parameters of normal conducting pulsed guns can be potentially met by SRF guns operating cw. Since more than a decade DESY in collaboration with TJNAF, NCBJ, BNL, HZB and HZDR performs R&D to develop an all superconducting RF gun with a lead cathode. In the frame of E-XFEL cw upgrade feasibility studies, the SRF-gun R&D program gained more attention and support. Within the next few years we would like to demonstrate the performance of the all superconducting injector required for the E-XFEL upgrade. The selected approach offers advantages w.r.t. the cleanliness of the superconducting surface, but requires a complete disassembly of a cryostat and stripping the gun cavity in a clean room to exchange the cathode. Thus it is practical only when the life time of the cathode is at least several months. In this paper we present the actual status of the R&D program, next steps and the longer term plans.
	Slides MOPO037 [1.966 MB]
	Poster MOPO037 [3.774 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO037
About •	paper received ※ 11 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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MOPO038	RF Operation Experience at the European XFEL	109
MOOP09	use link to see paper's listing under its alternate paper code
	J. Branlard, V. Ayvazyan, Ł. Butkowski, M.K. Grecki, M. Hierholzer, M.G. Hoffmann, M. Hoffmann, M. Killenberg, D. Kostin, T. Lamb, L. Lilje, U. Mavrič, M. Omet, S. Pfeiffer, R. Rybaniec, H. Schlarb, Ch. Schmidt, N. Shehzad, V. Vogel, N. Walker DESY, Hamburg, Germany
	After its successful commissioning which took place during the first half of 2017, the European X-ray free electron laser is in now in regular operation delivering photons to users since September 2017. This paper presents an overview on the experience gathered during the first couple of years of operation. In particular, the focus is set on RF operation, maintenance activities, availability and typical failures. A first look on machine performance in terms of RF and beam stability, energy reach, radiation related investigations and microphonics studies will also be presented.
	Slides MOPO038 [2.421 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO038
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO039	Status Update of the Fast Energy Corrector Cavity at FLASH	112
	S. Pfeiffer, J. Branlard, Ł. Butkowski, M. Hierholzer, M. Hoffmann, K. Honkavaara, H. Schlarb, Ch. Schmidt, S. Schreiber, M. Vogt, J. Zemella DESY, Hamburg, Germany M. Fakhari CFEL, Hamburg, Germany
	Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453. Linear accelerator facilities driving a free-electron laser require femtosecond precision synchronization between external laser systems and the electron beam. Such high precision is required for pump-probe experiments and also for example for the electron bunch injection into a plasma bubble for laser plasma acceleration. An upgrade of the fast intra-train beam-based feedback system is planned at the Free-Electron Laser FLASH in Hamburg, Germany. This linear accelerator is based on superconducting (SRF) technology operating with pulse trains of maximum 1 MHz bunch repetition rate. Arrival time fluctuations of the electron beam are correctable by introducing small energy modulations prior to the magnetic bunch compressor. This contribution focuses on the design and the characterization of a normal-conducting RF (NRF) cavity with large bandwidth, mandatory to correct fast arrival time fluctuations. The cavity has recently been installed in the FLASH beamline. First measurements with the new cavity will be presented.
	Poster MOPO039 [1.884 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO039
About •	paper received ※ 13 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO040	Coherent Synchrotron Radiation Monitor for Microbunching Instability in XFEL	115
MOOP05	use link to see paper's listing under its alternate paper code
SPWR002	use link to see paper's listing under its alternate paper code
	J.H. Ko, I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea H.-S. Kang, C. Kim, G. Kim PAL, Pohang, Kyungbuk, Republic of Korea
	The microbunching instability is an important issue in an X-ray Free Electron Laser (XFEL). The intensity of the FEL can be reduced significantly by the microbunching instability so that the laser heater is widely used to reduce it. In the X-ray Free Electron Laser of the Pohang Accelerator Laboratory (PAL-XFEL), to directly monitor the microbunching instability, a visible CCD camera was included into the coherent radiation monitor (CRM) which uses a pyroelectric detector. It enabled us to measure the microbunching instability more clearly and optimize the FEL lasing in the PAL-XFEL.
	Slides MOPO040 [1.125 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO040
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO041	Performance Test Results of Magnet Power Supply	118
	K.-H. Park, J.H. Han, S.-H. Jeong, Y.G. Jung, D.E. Kim, M.J. Kim, H.-G. Lee, S.B. Lee, B.G. Oh, H.S. Suh PAL, Pohang, Kyungbuk, Republic of Korea
	A high stable magnet power supply (MPS) was developed, which was a bipolar type with 200A of the output current at the 40V of output voltage. The MPS has been implemented by the digital signal processing technology using the DSP, FPGA, ADCs and so on. The output current stability of the MPS showed about 6ppm peak-to-peak in a short term experiment at 200A of its full output current. The long term stability was shown in 15 ppm peak-to-peak for 10 hours at 200A. And the others experimental results about the MPS were shown in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO041
About •	paper received ※ 31 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO042	Evolutionary Many-objective Optimization Algorithm for Large-bandwidth Free-Electron-Laser Generation	121
SPWR003	use link to see paper's listing under its alternate paper code
	J.W. Yan, H.X. Deng SINAP, Shanghai, People’s Republic of China
	Funding: National Natural Science Foundation of China , the National Key Research and Development Program of China, the Young Elite Scientist Sponsorship Program by CAST and Ten Thousand Talent Program. X-ray free-electron lasers (XFELs) are leading-edge instruments in a wide range of research fields. Besides pursuing narrow bandwidth FEL pulses, the large-bandwidth XFEL pulses are very useful in various spectroscopy experiments, multi-wavelength anomalous diffraction, and X-ray crystallography. Overcompression operation scheme can be utilized to generate electron beams with large energy chirp which is benefit for bandwidth broadening. Recently, an evolutionary many-objective (having four or more objectives) algorithm, NSGA-III, was used to optimize the electron beam parameters in the overcompression including energy chirp, energy spread, current profile, peak current, and projected emittance. In this paper, combining with the Xie’s semianalytical estimate formula, the NSGA-III is utilized to find an optimal working point of linac by optimizing the XFEL pulse properties directly. Start-to-end numerical simulations based on the Shanghai soft X-ray Free-Electron Laser user facility parameters demonstrate that a full bandwidth of 4.75% can be generated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO042
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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WE1A05	SwissFEL Linac Commissioning Status, Current Performance and Future Plans	605
	P. Craievich PSI, Villigen PSI, Switzerland
	SwissFEL, the hard x-ray free-electron laser facility at PSI, is in an advanced commissioning phase. The commissioning of the 5.8 GeV Linac started in 2016 and the first FEL pilot-experiments were performed at a reduced beam energy in the end of 2017. In 2018, it is foreseen to progressively increase the electron beam energy and photon energy up to the maximum design values, interleaved by several FEL pilot experiments. This paper gives an overview of the commissioning progress including the achieved machine performance and first operational experience.
	Slides WE1A05 [10.370 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-WE1A05
About •	paper received ※ 18 September 2018 paper accepted ※ 09 October 2018 issue date ※ 18 January 2019
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FR2A02	Commissioning of the European XFEL	994
	D. Nölle DESY, Hamburg, Germany
	The construction of the European XFEL has been finished at the end of 2016 and commissioning has been started. Meanwhile the entire facility, driving 3 free-electron-lasers in the hard and soft X-ray regime, is in operation. This contribution will report on commissioning and transition to operation, as well as on the first user runs.
	Slides FR2A02 [11.022 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-FR2A02
About •	paper received ※ 04 September 2018 paper accepted ※ 17 October 2018 issue date ※ 18 January 2019
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Paper

Title

Page

MO2A01

XFEL Projects in China

Z.T. Zhao, D. Wang
SINAP, Shanghai, People’s Republic of China

840MeV SXFEL is the first soft X-ray FEL built in Shanghai, now it’s in the commissiong stage. Also in Shanghai light source, a Hard X-ray 8GeV CW FEL has been proposed many years ago, and presumably will be approved in 2018.

Slides MO2A01 [19.783 MB]

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MO2A02

Linac Based Light Source Activities at THU

Y. C. Du, L.X. Yan
TUB, Beijing, People’s Republic of China

The high brightness electron linac based on a photocathode RF gun was established in Tsinghua University for the study of Thomson scattering x-ray and THz radiation light sources. Recent THz radiation research activities with tunable bunch trains, specially on their generation and diagnostics, will be presented. Experiments on coherent undulator radiation, coherent transition radiation, coherent Smith-Purcell radiation, dielectric wakefield radiation were performed. Another part of this talk will be focused on the recent progress in linac based ICS source at Tsinghua University, including the experiments on X/gamma-ray generation, diagnostic, and its applications in advanced X-ray imaging. And the design of a new compact ICS gamma-ray sources will also be discussed in this talk.

Slides MO2A02 [12.656 MB]

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MO2A04

Compact SRF Linac for High Brilliance Inverse Compton Scattering Light Source

19

K.E. Deitrick, J.R. Delayen, G.A. Krafft, B. Terzić
ODU, Norfolk, Virginia, USA
J.R. Delayen, G.A. Krafft
JLab, Newport News, Virginia, USA

New designs for compact SRF linacs can produce micron-size electron beams. These can can be used for inverse Compton scattering light sources of exceptional flux and brilliance.

Slides MO2A04 [1.717 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO2A04

About •

paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO034

Dielectric Waveguide-Based THz Radiator Study for SwissFEL

94

MOOP06

use link to see paper's listing under its alternate paper code

L. Shi, S. Bettoni, M.M. Dehler, E. Ferrari, B. Hermann, R. Ischebeck, F. Marcellini, S. Reiche, V.G. Thominet
PSI, Villigen PSI, Switzerland
A.K. Mittelbach
Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany

Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 701647
THz pulses have many unique properties in terms of radiation matter interaction. In particular their non-ionizing excitation of phonons in matter makes them a preferred pump for pump-probe studies at free electron lasers. In order to enrich the scientific potentials at SwissFEL (Swiss Free Electron Laser), which can provide ultrashort soft and hard X-ray pulses, we plan to build an economic THz radiator in the range of 1-20 THz by passing the spent electron beam through a dielectric lined tube after the electron beam has generated X-rays. These THz pulses will be transported to the photon user station. Since SwissFEL operates with 2 bunches, serving two beamlines, THz from the first bunch can be used at the user station of the second bunch to allow for pump arrival time before the probe. The core of such a THz generation setup is the dielectric lined tube and the relativistic electron beam. This paper reports on the numerical study of these tubes, in terms of mode structure, energy, pulse length etc, which are essential parameters for the pump-probe experiments. These tubes will be fabricated and tested in the near future in the electron beam line for the soft X-ray of SwissFEL.

Slides MOPO034 [1.471 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO034

About •

paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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MOPO035

Status of CLARA Front End Commissioning

98

MOOP03

use link to see paper's listing under its alternate paper code

D. Angal-Kalinin, A.D. Brynes, S.R. Buckley, P.A. Corlett, L.S. Cowie, K.D. Dumbell, D.J. Dunning, P.C. Hornickel, F. Jackson, J.K. Jones, J.W. McKenzie, B.L. Militsyn, A.J. Moss, T.C.Q. Noakes, M.D. Roper, D.J. Scott, B.J.A. Shepherd, E.W. Snedden, N. Thompson, C. Tollervey, D.A. Walsh, T.M. Weston, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.J. Cash, R.F. Clarke, G. Cox, C. Hodgkinson, R.J. Smith, J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
K.D. Dumbell, B.J.A. Shepherd
Cockcroft Institute, Warrington, Cheshire, United Kingdom

CLARA (Compact Linear Accelerator for Research and Applications) is a Free Electron Laser (FEL) test facility under development at Daresbury Laboratory. The principal aim of CLARA is to test advanced FEL schemes which can later be implemented on existing and future short wavelength FELs. We report on the commissioning of the CLARA front end, consisting of a photoinjector and the first linac section, and merger into the existing VELA (Versatile Electron Linear Accelerator) beamline.

Slides MOPO035 [1.870 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO035

About •

paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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MOPO036

Status of the 10 MW MBKs during Commissioning of the European XFEL in DESY

102

MOOP04

use link to see paper's listing under its alternate paper code

V. Vogel (Fogel), Ł. Butkowski, A. Cherepenko, S. Choroba, J. Hartung
DESY, Hamburg, Germany

At present 26 RF stations for European XFEL are in operation. Each of the RF stations consists of a HV modulator located in a separate building on the DESY campus, up to 1600 m long 10 kV HV cables that connect the modulator and the HV pulse transformer located in the underground tunnel, 120kV, 3 m long HV cable connecting the HV pulse transformer and the connection module of the horizontal multi-beam klystron. Two RF stations of the injector have already achieved about 20000 hours of operation, RF stations of the XFEL bunch compressor area have operated up to 11000 hours and in the XFEL main linac up to 8000 hours. To increase the lifetime of the klystrons, we use a fast protection system (KLM) that is based on the comparison of the actual RF shape and the expected RF shape. In the case of a difference exceeding a certain margin, for example, in the case of RF breakdown in a klystron or RF breakdown in a waveguide system, the KLM quickly, shorter than 500 ns, switches off the input RF signal. Thus, it does prevents the vacuum level in the klystron worsen too much or it minimizes the RF overvoltage time at the output windows of the klystron in case of breakdown in waveguides.

Slides MOPO036 [5.241 MB]

Poster MOPO036 [0.658 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO036

About •

paper received ※ 05 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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

MOPO037

SRF Gun Development at DESY

105

MOOP07

use link to see paper's listing under its alternate paper code

E. Vogel, S. Barbanotti, I. Hartl, K. Jensch, D. Klinke, D. Kostin, W.-D. Möller, M. Schmökel, J.K. Sekutowicz, S. Sievers, N. Steinhau-Kühl, A.A. Sulimov, J.H. Thie, H. Weise, L. Winkelmann, B. van der Horst
DESY, Hamburg, Germany
J.A. Lorkiewicz, R. Nietubyć
NCBJ, Świerk/Otwock, Poland
J. Smedley
BNL, Upton, Long Island, New York, USA
J. Teichert
HZDR, Dresden, Germany
M. Wiencek
IFJ-PAN, Kraków, Poland

A future upgrade of the European XFEL (E-XFEL) foresees an additional cw operation mode increasing the flexibility in the photon beam time structure. This mode requires among others a cw operating photo injector. We believe that using an SRF gun is the preferred approach as the beam parameters of normal conducting pulsed guns can be potentially met by SRF guns operating cw. Since more than a decade DESY in collaboration with TJNAF, NCBJ, BNL, HZB and HZDR performs R&D to develop an all superconducting RF gun with a lead cathode. In the frame of E-XFEL cw upgrade feasibility studies, the SRF-gun R&D program gained more attention and support. Within the next few years we would like to demonstrate the performance of the all superconducting injector required for the E-XFEL upgrade. The selected approach offers advantages w.r.t. the cleanliness of the superconducting surface, but requires a complete disassembly of a cryostat and stripping the gun cavity in a clean room to exchange the cathode. Thus it is practical only when the life time of the cathode is at least several months. In this paper we present the actual status of the R&D program, next steps and the longer term plans.

Slides MOPO037 [1.966 MB]

Poster MOPO037 [3.774 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO037

About •

paper received ※ 11 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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MOPO038

RF Operation Experience at the European XFEL

109

MOOP09

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J. Branlard, V. Ayvazyan, Ł. Butkowski, M.K. Grecki, M. Hierholzer, M.G. Hoffmann, M. Hoffmann, M. Killenberg, D. Kostin, T. Lamb, L. Lilje, U. Mavrič, M. Omet, S. Pfeiffer, R. Rybaniec, H. Schlarb, Ch. Schmidt, N. Shehzad, V. Vogel, N. Walker
DESY, Hamburg, Germany

After its successful commissioning which took place during the first half of 2017, the European X-ray free electron laser is in now in regular operation delivering photons to users since September 2017. This paper presents an overview on the experience gathered during the first couple of years of operation. In particular, the focus is set on RF operation, maintenance activities, availability and typical failures. A first look on machine performance in terms of RF and beam stability, energy reach, radiation related investigations and microphonics studies will also be presented.

Slides MOPO038 [2.421 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO038

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO039

Status Update of the Fast Energy Corrector Cavity at FLASH

112

S. Pfeiffer, J. Branlard, Ł. Butkowski, M. Hierholzer, M. Hoffmann, K. Honkavaara, H. Schlarb, Ch. Schmidt, S. Schreiber, M. Vogt, J. Zemella
DESY, Hamburg, Germany
M. Fakhari
CFEL, Hamburg, Germany

Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453.
Linear accelerator facilities driving a free-electron laser require femtosecond precision synchronization between external laser systems and the electron beam. Such high precision is required for pump-probe experiments and also for example for the electron bunch injection into a plasma bubble for laser plasma acceleration. An upgrade of the fast intra-train beam-based feedback system is planned at the Free-Electron Laser FLASH in Hamburg, Germany. This linear accelerator is based on superconducting (SRF) technology operating with pulse trains of maximum 1 MHz bunch repetition rate. Arrival time fluctuations of the electron beam are correctable by introducing small energy modulations prior to the magnetic bunch compressor. This contribution focuses on the design and the characterization of a normal-conducting RF (NRF) cavity with large bandwidth, mandatory to correct fast arrival time fluctuations. The cavity has recently been installed in the FLASH beamline. First measurements with the new cavity will be presented.

Poster MOPO039 [1.884 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO039

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paper received ※ 13 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO040

Coherent Synchrotron Radiation Monitor for Microbunching Instability in XFEL

115

MOOP05

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SPWR002

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J.H. Ko, I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
H.-S. Kang, C. Kim, G. Kim
PAL, Pohang, Kyungbuk, Republic of Korea

The microbunching instability is an important issue in an X-ray Free Electron Laser (XFEL). The intensity of the FEL can be reduced significantly by the microbunching instability so that the laser heater is widely used to reduce it. In the X-ray Free Electron Laser of the Pohang Accelerator Laboratory (PAL-XFEL), to directly monitor the microbunching instability, a visible CCD camera was included into the coherent radiation monitor (CRM) which uses a pyroelectric detector. It enabled us to measure the microbunching instability more clearly and optimize the FEL lasing in the PAL-XFEL.

Slides MOPO040 [1.125 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO040

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO041

Performance Test Results of Magnet Power Supply

118

K.-H. Park, J.H. Han, S.-H. Jeong, Y.G. Jung, D.E. Kim, M.J. Kim, H.-G. Lee, S.B. Lee, B.G. Oh, H.S. Suh
PAL, Pohang, Kyungbuk, Republic of Korea

A high stable magnet power supply (MPS) was developed, which was a bipolar type with 200A of the output current at the 40V of output voltage. The MPS has been implemented by the digital signal processing technology using the DSP, FPGA, ADCs and so on. The output current stability of the MPS showed about 6ppm peak-to-peak in a short term experiment at 200A of its full output current. The long term stability was shown in 15 ppm peak-to-peak for 10 hours at 200A. And the others experimental results about the MPS were shown in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO041

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paper received ※ 31 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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MOPO042

Evolutionary Many-objective Optimization Algorithm for Large-bandwidth Free-Electron-Laser Generation

121

SPWR003

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J.W. Yan, H.X. Deng
SINAP, Shanghai, People’s Republic of China

Funding: National Natural Science Foundation of China , the National Key Research and Development Program of China, the Young Elite Scientist Sponsorship Program by CAST and Ten Thousand Talent Program.
X-ray free-electron lasers (XFELs) are leading-edge instruments in a wide range of research fields. Besides pursuing narrow bandwidth FEL pulses, the large-bandwidth XFEL pulses are very useful in various spectroscopy experiments, multi-wavelength anomalous diffraction, and X-ray crystallography. Overcompression operation scheme can be utilized to generate electron beams with large energy chirp which is benefit for bandwidth broadening. Recently, an evolutionary many-objective (having four or more objectives) algorithm, NSGA-III, was used to optimize the electron beam parameters in the overcompression including energy chirp, energy spread, current profile, peak current, and projected emittance. In this paper, combining with the Xie’s semianalytical estimate formula, the NSGA-III is utilized to find an optimal working point of linac by optimizing the XFEL pulse properties directly. Start-to-end numerical simulations based on the Shanghai soft X-ray Free-Electron Laser user facility parameters demonstrate that a full bandwidth of 4.75% can be generated.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO042

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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WE1A05

SwissFEL Linac Commissioning Status, Current Performance and Future Plans

605

P. Craievich
PSI, Villigen PSI, Switzerland

SwissFEL, the hard x-ray free-electron laser facility at PSI, is in an advanced commissioning phase. The commissioning of the 5.8 GeV Linac started in 2016 and the first FEL pilot-experiments were performed at a reduced beam energy in the end of 2017. In 2018, it is foreseen to progressively increase the electron beam energy and photon energy up to the maximum design values, interleaved by several FEL pilot experiments. This paper gives an overview of the commissioning progress including the achieved machine performance and first operational experience.

Slides WE1A05 [10.370 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-WE1A05

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paper received ※ 18 September 2018 paper accepted ※ 09 October 2018 issue date ※ 18 January 2019

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FR2A02

Commissioning of the European XFEL

994

D. Nölle
DESY, Hamburg, Germany

The construction of the European XFEL has been finished at the end of 2016 and commissioning has been started. Meanwhile the entire facility, driving 3 free-electron-lasers in the hard and soft X-ray regime, is in operation. This contribution will report on commissioning and transition to operation, as well as on the first user runs.

Slides FR2A02 [11.022 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-FR2A02

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paper received ※ 04 September 2018 paper accepted ※ 17 October 2018 issue date ※ 18 January 2019

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