FEL2013 - List of Authors (Yurkov, M.V.)

Paper

Title

Page

Feasibility of CW and LP Operation of the XFEL Linac

189

J.K. Sekutowicz, V. Ayvazyan, J. Branlard, M. Ebert, J. Eschke, T. Feldmann, A. Gössel, D. Kostin, I.M. Kudla, W. Merz, F. Mittag, C. Müller, R. Onken, I. Sandvoss, E. Schneidmiller, A.A. Sulimov, M.V. Yurkov
DESY, Hamburg, Germany
W. Cichalewski, A. Piotrowski, K.P. Przygoda
TUL-DMCS, Łódź, Poland
K. Czuba
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
W. Jałmużna
Embedded Integrated Control Systems GmbH, Hamburg, Germany
J. Szewiński
NCBJ, Świerk/Otwock, Poland

The European XFEL superconducting linac is based on cavities and cryomodules (CM) developed for TESLA linear collider. The XFEL linac will operate nominally in short pulse (sp) mode with 1.3 ms RF pulses (650 μs rise time and 650 μs long bunch train). For 240 ns bunch spacing and 10 Hz RF-pulse repetition rate, up to 27000 bunches per second can be accelerated to 17.5 GeV to generate uniquely high average brilliance photon beams at very short wavelengths. While many experiments can take advantage of full bunch trains, others prefer an increased to several μ-seconds intra-pulse distance between bunches, or short bursts with a kHz repetition rate. For these types of experiments, the high average brilliance can be preserved only with duty factors much larger than that of the currently proposed sp operation. In this contribution, we discuss progress in the R&D program for future upgrade of the European XFEL linac, namely an operation in the continuous wave (cw) and long pulse (lp) mode, which will allow for more flexibility in the electron and photon beam time structure.

Slides TUOCNO04 [8.910 MB]

TUPSO64

Short SASE-FEL Pulses at FLASH

379

J. Rönsch-Schulenburg, E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Roßbach
Uni HH, Hamburg, Germany
G. Brenner, C. Gerth, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov
DESY, Hamburg, Germany

Funding: This project has been supported by BMBF under contract 05K10GU2 & FS FLASH 301
FLASH is a high-gain free-electron laser (FEL) in the soft x-ray range. This paper discusses the production of very short FEL pulses in the SASE-mode without an external seeding signal at FLASH in the optimal case the single-spike operation. A new photo-injector laser has been commissioned, which allows the generation of shorter bunches with low bunch charge directly at the photo-cathode. This shorter injector laser reduces the required bunch compression for short pulses and thus allows a stable SASE performance with shorter pulses. First SASE performance using the new injector laser has been demonstrated and electron bunch and FEL radiation properties have been measured. Beam dynamics as well as the optimization of bunch diagnostics for low charge and short bunches are discussed.

WEOBNO04

Integration of Accelerator Based IR/THz Source for Pump Probe Experiments in the Infrastructure of the European XFEL

M.V. Yurkov, E. Schneidmiller
DESY, Hamburg, Germany
M. Gensch
HZDR, Dresden, Germany
M. Izquierdo
XFEL. EU, Hamburg, Germany
M. Krasilnikov, F. Stephan
DESY Zeuthen, Zeuthen, Germany

We analyze the scope of pump-probe experiments at the European XFEL involving IR/THz and x-ray pulses. Different experiments impose different requirements on the properties of the IR/THz source like wavelength range, spectral properties, intensity, pulse duration, polarization, synchronization capabilities, repetition rate, etc. Our previous analysis have shown that the most universal solution of the problem of the IR/THz radiation source is an accelerator based source. The electron accelerator is similar to that operating at the PITZ facility. It consists of an rf gun and a warm (or cold) accelerating section. Powerful, coherent radiation with prescribed temporal, spectral and polarization properties is generated in a set of radiators like undulators (using mechanism of SASE FEL for short wavelength and coherent undulator radiation for long wavelength), edge radiators, OTR foils, diffraction radiators. Location of the electron source close to the experiment would allow performing of pump-probe experiments involving also ultrashort electron pulses. In this paper we discuss problems of the integration of the accelerator based THz source into infrastructure of the European XFEL.

Slides WEOBNO04 [3.339 MB]

WEICNO01

Harmonic Lasing in X-Ray FELs

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Contrary to nonlinear harmonic generation, harmonic lasing in a high-gain FEL can provide much more intense, stable,and narrow-band FEL beam which is easier to handle if the fundamental is suppressed. We perform a parametrization of the solution of eigenvalue equation for lasing at odd harmonics, and present explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of X-ray beam. We discover that in a part of the parameter space, corresponding to the operating range of soft X-ray beamlines of X-ray FEL facilities, harmonics can grow faster than the fundamental. We suggest that harmonic lasing can be widely used in the existing or planned X-ray FEL facilities. LCLS after a minor modification can lase at the 3rd harmonic up to the photon energy of 25-30 keV providing multi-gigawatt power level. At the European XFEL the harmonic lasing would allow to extend operating range up to 100 keV, to reduce bandwidth and increase brilliance, etc.
Phys. Rev. ST-AB 15, 080702 (2012)

Slides WEICNO01 [1.558 MB]

WEPSO53

Harmonic Lasing at the LCLS

623

D.F. Ratner, Z. Huang, P.A. Montanez
SLAC, Menlo Park, California, USA
E. Allaria
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
W.M. Fawley, L.N. Rodes
LBNL, Berkeley, California, USA
E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Funding: Department of Energy
The LCLS beamlines deliver X-rays to users at photon energies up to 24 keV. With the fundamental wavelength limited to around 10 keV, there is user interest in the third harmonic, which can reach a few percent of the total beam power. McNeil et al* and Schneidmiller and Yurkov** have showed that introducing phase shifts or attenuators into the undulator line can increase harmonic power by driving lasing at the third harmonic. With the development of self-seeding chicanes, LCLS is now in position for a proof-of-principle experiment. Here we present simulations and plans for an experimental test following commissioning of the Soft X-ray Self-Seeding system.
*B.W.J. McNeil, G.R.M. Robb, M.W. Poole and N.R. Thompson, Phys. Rev. Lett., 96 084801 (2006)
**E. Schneidmiller and M. Yurkov, PR-STAB, 14 080702 (2012)

WEPSO56

Optical Design and Time-dependent Wavefront Propagation Simulation for a Hard X-Ray Split- and delay-unit for the European XFEL

627

S. Roling, B. Siemer, F. Wahlert, M. Wöstmann, H. Zacharias
Universität Muenster, Physikalisches Institut, Muenster, Germany
S. Braun, P. Gawlitza
Fraunhofer IWS, Dresden, Germany
O.V. Chubar
BNL, Upton, Long Island, New York, USA
L. Samoylova, H. Sinn
XFEL. EU, Hamburg, Germany
E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany
F. Siewert
HZB, Berlin, Germany
E. Ziegler
ESRF, Grenoble, France

For the European XFEL an x-ray split- and delay-unit (SDU) is built covering photon energies from 5 keV up to 20 keV. This SDU will enable time-resolved x-ray pump / x-ray probe experiments as well as sequential diffractive imaging on a femtosecond to picosecond time scale. The wavefront of the x-ray FEL pulses will be split by an edge of a silicon mirror coated with Mo/B4C and W/B4C multilayers. Both partial beams will then pass variable delay lines. For different wavelengths the angle of incidence onto the multilayer mirrors will be adjusted in order to match the Bragg condition. Hence, maximum delays between ± 2.5 ps at hν = 20 keV and up to ± 33 ps at hν = 5 keV will be possible. The time-dependent wave-optics simulations have been done with SRW software, for the fundamental and the 3rd harmonic. The XFEL radiation was simulated both in the Gaussian approximation as well as using an output of time-dependent SASE code FAST. Main features of the optical layout, including diffraction on the splitter edge, and optics imperfections were taken into account. Impact of these effects on the possibility to characterize spatial-temporal properties of FEL pulses are analyzed.

WEPSO59

A Possible Upgrade of FLASH for Harmonic Lasing Down to 1.3 nm

646

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

We propose the 3rd harmonic lasing in a new FLASH undulator as a way to produce intense, narrow-band, and stable SASE radiation down to 1.3 nm with the present accelerator energy of 1.25 GeV. To provide optimal conditions for harmonic lasing, we suggest to suppress the fundamental with the help of a special set of phase shifters. We rely on the standard technology of gap-tunable planar hybrid undulators, and choose the period of 2.3 cm and the minimum gap of 0.9 cm; total length of the undulator system is 34.5 m. We demonstrate that the 3rd harmonic lasing at 1.3 nm provides peak power at a gigawatt level and the narrow intrinsic bandwidth, 0.1% (FWHM). Pulse duration can be controlled in the range of a few tens of femtoseconds, and the peak brilliance reaches the value of 10³¹ photons/(s mrad² mm² 0.1% BW). With the given undulator design, a standard option of lasing at the fundamental wavelength to saturation is possible through the entire water window and at longer wavelengths. In this paper we briefly consider additional options such as polarization control, bandwidth reduction, self-seeding, X-ray pulse compression, and two-color operation.

WEPSO60

A Method for Obtaining High Degree of Circular Polarization at X-ray FELs

651

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Baseline design of many X-ray FEL undulators assumes a planar configuration which results in a linear polarization of SASE FEL radiation. However, many users experiments would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a helical afterburner, but then one should have an efficient method to suppress linearly polarized background from the main undulator. In this paper we consider a new method for such a suppression which is illustrated with the parameters of the soft X-ray undulator SASE3 of the European X-ray FEL.

WEPSO78

Harmonic Lasing Self-seeded FEL

700

M.V. Yurkov, E. Schneidmiller
DESY, Hamburg, Germany

In this paper we perform analysis of capabilities of SASE FELs at the European XFEL for generation of narrow band radiation. An approach based on application of harmonic lasing self-seeding (HLSS) is under study[*]. Effective harmonic lasing occurs in the exponential gain regime in the first part of the undulator, making sure that the fundamental frequency is well below saturation. In the second part of the undulator the value of undulator parameter is reduced such that now the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is defined by the harmonic lasing (i.e. it is reduced by a significant factor depending on harmonic number) but the saturation power is still as high as in the reference case of lasing at the fundamental, i.e. brilliance increases. Application of the undulator tapering in the deep nonlinear regime would allow to generate higher peak powers approaching TW level.
* E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 15, 080702 (2012)

WEPSO80

Coherence Properties of the Radiation From FLASH

704

M.V. Yurkov, E. Schneidmiller
DESY, Hamburg, Germany

Several user groups at FLASH use higher odd harmonics (3rd and 5th) of the radiation in experiments. Some applications require knowledge of coherence properties of the radiation at he fundamental and higher harmonics. In this paper we presents results of the studies of coherence properties of the radiation from FLASH operating at radiation wavelength of 6.x nm at the fundamental harmonic, and higher odd harmonics (2.x nm and 1.x nm) at electron energy of 1 GeV.

Paper	Title	Page
TUOCNO04	Feasibility of CW and LP Operation of the XFEL Linac	189
	J.K. Sekutowicz, V. Ayvazyan, J. Branlard, M. Ebert, J. Eschke, T. Feldmann, A. Gössel, D. Kostin, I.M. Kudla, W. Merz, F. Mittag, C. Müller, R. Onken, I. Sandvoss, E. Schneidmiller, A.A. Sulimov, M.V. Yurkov DESY, Hamburg, Germany W. Cichalewski, A. Piotrowski, K.P. Przygoda TUL-DMCS, Łódź, Poland K. Czuba Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland W. Jałmużna Embedded Integrated Control Systems GmbH, Hamburg, Germany J. Szewiński NCBJ, Świerk/Otwock, Poland
	The European XFEL superconducting linac is based on cavities and cryomodules (CM) developed for TESLA linear collider. The XFEL linac will operate nominally in short pulse (sp) mode with 1.3 ms RF pulses (650 μs rise time and 650 μs long bunch train). For 240 ns bunch spacing and 10 Hz RF-pulse repetition rate, up to 27000 bunches per second can be accelerated to 17.5 GeV to generate uniquely high average brilliance photon beams at very short wavelengths. While many experiments can take advantage of full bunch trains, others prefer an increased to several μ-seconds intra-pulse distance between bunches, or short bursts with a kHz repetition rate. For these types of experiments, the high average brilliance can be preserved only with duty factors much larger than that of the currently proposed sp operation. In this contribution, we discuss progress in the R&D program for future upgrade of the European XFEL linac, namely an operation in the continuous wave (cw) and long pulse (lp) mode, which will allow for more flexibility in the electron and photon beam time structure.
	Slides TUOCNO04 [8.910 MB]

TUPSO64	Short SASE-FEL Pulses at FLASH	379
	J. Rönsch-Schulenburg, E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Roßbach Uni HH, Hamburg, Germany G. Brenner, C. Gerth, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov DESY, Hamburg, Germany
	Funding: This project has been supported by BMBF under contract 05K10GU2 & FS FLASH 301 FLASH is a high-gain free-electron laser (FEL) in the soft x-ray range. This paper discusses the production of very short FEL pulses in the SASE-mode without an external seeding signal at FLASH in the optimal case the single-spike operation. A new photo-injector laser has been commissioned, which allows the generation of shorter bunches with low bunch charge directly at the photo-cathode. This shorter injector laser reduces the required bunch compression for short pulses and thus allows a stable SASE performance with shorter pulses. First SASE performance using the new injector laser has been demonstrated and electron bunch and FEL radiation properties have been measured. Beam dynamics as well as the optimization of bunch diagnostics for low charge and short bunches are discussed.

WEOBNO04	Integration of Accelerator Based IR/THz Source for Pump Probe Experiments in the Infrastructure of the European XFEL
	M.V. Yurkov, E. Schneidmiller DESY, Hamburg, Germany M. Gensch HZDR, Dresden, Germany M. Izquierdo XFEL. EU, Hamburg, Germany M. Krasilnikov, F. Stephan DESY Zeuthen, Zeuthen, Germany
	We analyze the scope of pump-probe experiments at the European XFEL involving IR/THz and x-ray pulses. Different experiments impose different requirements on the properties of the IR/THz source like wavelength range, spectral properties, intensity, pulse duration, polarization, synchronization capabilities, repetition rate, etc. Our previous analysis have shown that the most universal solution of the problem of the IR/THz radiation source is an accelerator based source. The electron accelerator is similar to that operating at the PITZ facility. It consists of an rf gun and a warm (or cold) accelerating section. Powerful, coherent radiation with prescribed temporal, spectral and polarization properties is generated in a set of radiators like undulators (using mechanism of SASE FEL for short wavelength and coherent undulator radiation for long wavelength), edge radiators, OTR foils, diffraction radiators. Location of the electron source close to the experiment would allow performing of pump-probe experiments involving also ultrashort electron pulses. In this paper we discuss problems of the integration of the accelerator based THz source into infrastructure of the European XFEL.
	Slides WEOBNO04 [3.339 MB]

WEICNO01	Harmonic Lasing in X-Ray FELs
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Contrary to nonlinear harmonic generation, harmonic lasing in a high-gain FEL can provide much more intense, stable,and narrow-band FEL beam which is easier to handle if the fundamental is suppressed. We perform a parametrization of the solution of eigenvalue equation for lasing at odd harmonics, and present explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of X-ray beam. We discover that in a part of the parameter space, corresponding to the operating range of soft X-ray beamlines of X-ray FEL facilities, harmonics can grow faster than the fundamental. We suggest that harmonic lasing can be widely used in the existing or planned X-ray FEL facilities. LCLS after a minor modification can lase at the 3rd harmonic up to the photon energy of 25-30 keV providing multi-gigawatt power level. At the European XFEL the harmonic lasing would allow to extend operating range up to 100 keV, to reduce bandwidth and increase brilliance, etc. Phys. Rev. ST-AB 15, 080702 (2012)
	Slides WEICNO01 [1.558 MB]

WEPSO53	Harmonic Lasing at the LCLS	623
	D.F. Ratner, Z. Huang, P.A. Montanez SLAC, Menlo Park, California, USA E. Allaria Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy W.M. Fawley, L.N. Rodes LBNL, Berkeley, California, USA E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Funding: Department of Energy The LCLS beamlines deliver X-rays to users at photon energies up to 24 keV. With the fundamental wavelength limited to around 10 keV, there is user interest in the third harmonic, which can reach a few percent of the total beam power. McNeil et al* and Schneidmiller and Yurkov** have showed that introducing phase shifts or attenuators into the undulator line can increase harmonic power by driving lasing at the third harmonic. With the development of self-seeding chicanes, LCLS is now in position for a proof-of-principle experiment. Here we present simulations and plans for an experimental test following commissioning of the Soft X-ray Self-Seeding system. B.W.J. McNeil, G.R.M. Robb, M.W. Poole and N.R. Thompson, Phys. Rev. Lett., 96 084801 (2006) *E. Schneidmiller and M. Yurkov, PR-STAB, 14 080702 (2012)

WEPSO56	Optical Design and Time-dependent Wavefront Propagation Simulation for a Hard X-Ray Split- and delay-unit for the European XFEL	627
	S. Roling, B. Siemer, F. Wahlert, M. Wöstmann, H. Zacharias Universität Muenster, Physikalisches Institut, Muenster, Germany S. Braun, P. Gawlitza Fraunhofer IWS, Dresden, Germany O.V. Chubar BNL, Upton, Long Island, New York, USA L. Samoylova, H. Sinn XFEL. EU, Hamburg, Germany E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany F. Siewert HZB, Berlin, Germany E. Ziegler ESRF, Grenoble, France
	For the European XFEL an x-ray split- and delay-unit (SDU) is built covering photon energies from 5 keV up to 20 keV. This SDU will enable time-resolved x-ray pump / x-ray probe experiments as well as sequential diffractive imaging on a femtosecond to picosecond time scale. The wavefront of the x-ray FEL pulses will be split by an edge of a silicon mirror coated with Mo/B4C and W/B4C multilayers. Both partial beams will then pass variable delay lines. For different wavelengths the angle of incidence onto the multilayer mirrors will be adjusted in order to match the Bragg condition. Hence, maximum delays between ± 2.5 ps at hν = 20 keV and up to ± 33 ps at hν = 5 keV will be possible. The time-dependent wave-optics simulations have been done with SRW software, for the fundamental and the 3rd harmonic. The XFEL radiation was simulated both in the Gaussian approximation as well as using an output of time-dependent SASE code FAST. Main features of the optical layout, including diffraction on the splitter edge, and optics imperfections were taken into account. Impact of these effects on the possibility to characterize spatial-temporal properties of FEL pulses are analyzed.

WEPSO59	A Possible Upgrade of FLASH for Harmonic Lasing Down to 1.3 nm	646
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	We propose the 3rd harmonic lasing in a new FLASH undulator as a way to produce intense, narrow-band, and stable SASE radiation down to 1.3 nm with the present accelerator energy of 1.25 GeV. To provide optimal conditions for harmonic lasing, we suggest to suppress the fundamental with the help of a special set of phase shifters. We rely on the standard technology of gap-tunable planar hybrid undulators, and choose the period of 2.3 cm and the minimum gap of 0.9 cm; total length of the undulator system is 34.5 m. We demonstrate that the 3rd harmonic lasing at 1.3 nm provides peak power at a gigawatt level and the narrow intrinsic bandwidth, 0.1% (FWHM). Pulse duration can be controlled in the range of a few tens of femtoseconds, and the peak brilliance reaches the value of 10³¹ photons/(s mrad² mm² 0.1% BW). With the given undulator design, a standard option of lasing at the fundamental wavelength to saturation is possible through the entire water window and at longer wavelengths. In this paper we briefly consider additional options such as polarization control, bandwidth reduction, self-seeding, X-ray pulse compression, and two-color operation.

WEPSO60	A Method for Obtaining High Degree of Circular Polarization at X-ray FELs	651
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Baseline design of many X-ray FEL undulators assumes a planar configuration which results in a linear polarization of SASE FEL radiation. However, many users experiments would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a helical afterburner, but then one should have an efficient method to suppress linearly polarized background from the main undulator. In this paper we consider a new method for such a suppression which is illustrated with the parameters of the soft X-ray undulator SASE3 of the European X-ray FEL.

WEPSO78	Harmonic Lasing Self-seeded FEL	700
	M.V. Yurkov, E. Schneidmiller DESY, Hamburg, Germany
	In this paper we perform analysis of capabilities of SASE FELs at the European XFEL for generation of narrow band radiation. An approach based on application of harmonic lasing self-seeding (HLSS) is under study[]. Effective harmonic lasing occurs in the exponential gain regime in the first part of the undulator, making sure that the fundamental frequency is well below saturation. In the second part of the undulator the value of undulator parameter is reduced such that now the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is defined by the harmonic lasing (i.e. it is reduced by a significant factor depending on harmonic number) but the saturation power is still as high as in the reference case of lasing at the fundamental, i.e. brilliance increases. Application of the undulator tapering in the deep nonlinear regime would allow to generate higher peak powers approaching TW level. E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 15, 080702 (2012)

WEPSO80	Coherence Properties of the Radiation From FLASH	704
	M.V. Yurkov, E. Schneidmiller DESY, Hamburg, Germany
	Several user groups at FLASH use higher odd harmonics (3rd and 5th) of the radiation in experiments. Some applications require knowledge of coherence properties of the radiation at he fundamental and higher harmonics. In this paper we presents results of the studies of coherence properties of the radiation from FLASH operating at radiation wavelength of 6.x nm at the fundamental harmonic, and higher odd harmonics (2.x nm and 1.x nm) at electron energy of 1 GeV.