IPAC2017 - List of Authors (Yurkov, M.V.)

Paper	Title	Page
WEPAB022	Background-free Harmonic Production in XFELs via a Reverse Undulator Taper	2618
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Nonlinear harmonics in X-ray FELs can be parasitically produced as soon as FEL reaches saturation, or can be radiated in dedicated afterburners. In both cases there is a strong background at the fundamental, since it is much stronger than harmonics. One can get around this problem by application of the recently proposed reverse undulator tapering. In this contribution we present numerical simulations of harmonic production in such a configuration as well as recent results from FLASH where the second and the third harmonics were efficiently generated with a low background at the fundamental. We also present the results for a high-contrast operation when the afterburner is tuned to the fundamental.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB022
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WEPAB023	First Operation of a Harmonic Lasing Self-Seeded FEL	2621
	E. Schneidmiller, B. Faatz, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, M. Tischer, M.V. Yurkov DESY, Hamburg, Germany
	Harmonic lasing is a perspective mode of operation of X-ray FEL user facilities that allows to provide brilliant beams of higher energy photons for user experiments. Another useful application of harmonic lasing is so called Harmonic Lasing Self-Seeded Free Electron Laser (HLSS FEL) that allows to improve spectral brightness of these facilities. In the past, harmonic lasing has been demonstrated in the FEL oscillators in infrared and visible wavelength ranges, but not in high-gain FELs and not at short wavelengths. In this paper we report on the first evidence of the harmonic lasing and the first operation of the HLSS FEL at the soft X-ray FEL user facility FLASH in the wavelength range between 4.5 nm and 15 nm. Spectral brightness was improved in comparison with Self-Amplified Spontaneous emission (SASE) FEL by a factor of six in the exponential gain regime. A better performance of HLSS FEL with respect to SASE FEL in the post-saturation regime with a tapered undulator was observed as well. The first demonstration of harmonic lasing in a high-gain FEL and at a short wavelength paves the way for a variety of applications of this new operation mode in X-ray FELs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB023
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WEPAB027	Frequency Doubler and Two-color Mode of Operation at Free Electron Laser FLASH2	2635
	M. Kuhlmann, E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	We report on the results of the first operation of a frequency doubler at free electron laser FLASH2. The scheme uses the feature of the variable gap undulator. Undulator is divided in two parts. The second part of the undulator is tuned to the double frequency of the first part. Amplification process in the first undulator part is stopped at the onset of the nonlinear regime, such that nonlinear higher harmonic bunching in the electron beam density becomes pronouncing, but the radiation level is still small to disturb the electron beam significantly. Modulated electron beam enters the second part of the undulator and generates radiation at the 2nd harmonic. Frequency doubler allows operation in a two-color mode and operation at shorter wavelengths with respect to standard SASE scheme. Tuning of the electron beam trajectory, phase shifters and compression allows to tune intensities of the first and the second harmonic. The shortest wavelength of 3.1 nm (photon energy 400 eV) has been achieved with frequency doubler scheme, which is significantly below the design value for the standard SASE option.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB027
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WEPAB029	Optimum Undulator Tapering of SASE FEL: From the Theory to Experiment	2639
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Optimization of the amplification process in FEL amplifier with diffraction effects taken into account results in a specific law of the undulator tapering []. It is a smooth function with quadratic behavior in the beginning of the tapering section which transforms to a linear behavior for a long undulator. In practice, undulator consists of a sequence of modules of fixed length separated with intersections. Two modes of undulator tapering can be implemented: step tapering, and smooth tapering. Procedure of the step tapering applies step change of the undulator gap from module to module, and smooth tapering assumes additional linear change of the gap along each module. In this report we simulate the performance of the both experimental options and compare with theoretical limit. [] E.A. Schneidmiller and M.V. Yurkov, Optimization of a high efficiency free electron laser amplifier, Phys. Rev. ST Accel. Beams 18 (2015) 030705.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB029
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THPAB132	MCP Based Detectors Installation in European XFEL	4031
	E. Syresin, O.I. Brovko, A.Yu. Grebentsov JINR, Dubna, Moscow Region, Russia W. Freund XFEL. EU, Hamburg, Germany J. Grünert European XFEL, Schenefeld, Germany M.V. Yurkov DESY, Hamburg, Germany
	An important task of the photon beam diagnostics at the European XFEL is providing reliable tools for measurements aiming at the search for and fine tuning of the amplification process in the SASE FEL. Radiation detectors based onμchannel plates (MCP) were prepared for such measurements. These detectors operate in a wide dynamic range from the level of spontaneous emission to the saturation level (between a few nJ to 25 mJ), and in a wide wavelength range from 0.05 nm to 0.4 nm for SASE1 and SASE2, and from 0.4 nm to 5.1 nm for SASE3. Photon pulse energies are measured at the MCP anode and with a photodiode. The transverse photon beam profile is measured by an MCP imager with phosphor screen anode. Three MCP devices are being installed, one in each of the three FEL beamlines (SASE1, SASE2, and SASE3). The units for SASE1 and SASE3 were already installed in the XFEL tunnel, and the technical commissioning of the MCP detectors and their electronics is progressing. Calibration and acceptance test experiments with beam are scheduled for early 2017.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB132
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Paper

Title

Page

Background-free Harmonic Production in XFELs via a Reverse Undulator Taper

2618

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

Nonlinear harmonics in X-ray FELs can be parasitically produced as soon as FEL reaches saturation, or can be radiated in dedicated afterburners. In both cases there is a strong background at the fundamental, since it is much stronger than harmonics. One can get around this problem by application of the recently proposed reverse undulator tapering. In this contribution we present numerical simulations of harmonic production in such a configuration as well as recent results from FLASH where the second and the third harmonics were efficiently generated with a low background at the fundamental. We also present the results for a high-contrast operation when the afterburner is tuned to the fundamental.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB022

Export •

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

WEPAB023

First Operation of a Harmonic Lasing Self-Seeded FEL

2621

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

Harmonic lasing is a perspective mode of operation of X-ray FEL user facilities that allows to provide brilliant beams of higher energy photons for user experiments. Another useful application of harmonic lasing is so called Harmonic Lasing Self-Seeded Free Electron Laser (HLSS FEL) that allows to improve spectral brightness of these facilities. In the past, harmonic lasing has been demonstrated in the FEL oscillators in infrared and visible wavelength ranges, but not in high-gain FELs and not at short wavelengths. In this paper we report on the first evidence of the harmonic lasing and the first operation of the HLSS FEL at the soft X-ray FEL user facility FLASH in the wavelength range between 4.5 nm and 15 nm. Spectral brightness was improved in comparison with Self-Amplified Spontaneous emission (SASE) FEL by a factor of six in the exponential gain regime. A better performance of HLSS FEL with respect to SASE FEL in the post-saturation regime with a tapered undulator was observed as well. The first demonstration of harmonic lasing in a high-gain FEL and at a short wavelength paves the way for a variety of applications of this new operation mode in X-ray FELs.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB023

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WEPAB027

Frequency Doubler and Two-color Mode of Operation at Free Electron Laser FLASH2

2635

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

We report on the results of the first operation of a frequency doubler at free electron laser FLASH2. The scheme uses the feature of the variable gap undulator. Undulator is divided in two parts. The second part of the undulator is tuned to the double frequency of the first part. Amplification process in the first undulator part is stopped at the onset of the nonlinear regime, such that nonlinear higher harmonic bunching in the electron beam density becomes pronouncing, but the radiation level is still small to disturb the electron beam significantly. Modulated electron beam enters the second part of the undulator and generates radiation at the 2nd harmonic. Frequency doubler allows operation in a two-color mode and operation at shorter wavelengths with respect to standard SASE scheme. Tuning of the electron beam trajectory, phase shifters and compression allows to tune intensities of the first and the second harmonic. The shortest wavelength of 3.1 nm (photon energy 400 eV) has been achieved with frequency doubler scheme, which is significantly below the design value for the standard SASE option.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB027

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WEPAB029

Optimum Undulator Tapering of SASE FEL: From the Theory to Experiment

2639

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

Optimization of the amplification process in FEL amplifier with diffraction effects taken into account results in a specific law of the undulator tapering [*]. It is a smooth function with quadratic behavior in the beginning of the tapering section which transforms to a linear behavior for a long undulator. In practice, undulator consists of a sequence of modules of fixed length separated with intersections. Two modes of undulator tapering can be implemented: step tapering, and smooth tapering. Procedure of the step tapering applies step change of the undulator gap from module to module, and smooth tapering assumes additional linear change of the gap along each module. In this report we simulate the performance of the both experimental options and compare with theoretical limit.
[*] E.A. Schneidmiller and M.V. Yurkov, Optimization of a high efficiency free electron laser amplifier, Phys. Rev. ST Accel. Beams 18 (2015) 030705.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB029

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THPAB132

MCP Based Detectors Installation in European XFEL

4031

E. Syresin, O.I. Brovko, A.Yu. Grebentsov
JINR, Dubna, Moscow Region, Russia
W. Freund
XFEL. EU, Hamburg, Germany
J. Grünert
European XFEL, Schenefeld, Germany
M.V. Yurkov
DESY, Hamburg, Germany

An important task of the photon beam diagnostics at the European XFEL is providing reliable tools for measurements aiming at the search for and fine tuning of the amplification process in the SASE FEL. Radiation detectors based onμchannel plates (MCP) were prepared for such measurements. These detectors operate in a wide dynamic range from the level of spontaneous emission to the saturation level (between a few nJ to 25 mJ), and in a wide wavelength range from 0.05 nm to 0.4 nm for SASE1 and SASE2, and from 0.4 nm to 5.1 nm for SASE3. Photon pulse energies are measured at the MCP anode and with a photodiode. The transverse photon beam profile is measured by an MCP imager with phosphor screen anode. Three MCP devices are being installed, one in each of the three FEL beamlines (SASE1, SASE2, and SASE3). The units for SASE1 and SASE3 were already installed in the XFEL tunnel, and the technical commissioning of the MCP detectors and their electronics is progressing. Calibration and acceptance test experiments with beam are scheduled for early 2017.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB132

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