FEL2015 - List of Keywords (diagnostics)

Paper	Title	Other Keywords	Page
MOP060	RFTweak 5 - An Efficient Longitudinal Beam Dynamics Code	GUI, controls, space-charge, radiation	176
	B. Beutner, H. Dinter, M. Dohlus DESY, Hamburg, Germany
	The shaping of the longitudinal phase space in bunch compression systems is essential for efficient FEL operation. RF systems and self-field interactions contribute to the overall phase space structure. The design of the various facilities relies on extensive beam dynamics simulations to define the longitudinal dynamics. However, in everyday control room applications such techniques are often not fast enough for efficient operation, e.g. for SASE tuning. Therefore efficient longitudinal beam dynamics codes are required while still maintaining reasonable accuracy. Our approach is to pre-calculate most of the required data for self-field interactions and store them on disc to reduce required online calculation time to a minimum. In this paper we present the fast longitudinal tracking code RFTweak 5, which includes wakes, space charge, and CSR interactions. With this code the full European XFEL with a 1M particles bunch is calculated on the order of minutes on a standard laptop. Neglecting CSR effects this time reduces to seconds.
	Poster MOP060 [0.799 MB]
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TUP053	Real-World Considerations for Crossed-Polarized Undulator Radiation Conversion	polarization, FEL, undulator, radiation	486
	W.M. Fawley, E. Allaria, E. Ferrari Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy E. Ferrari Università degli Studi di Trieste, Trieste, Italy
	Cross-polarized (X-POL) configurations are a means to produce circularly-polarized radiation output from purely planar-polarized undulators. Recent polarization results from both the FERMI FEL-1 [1] at XUV wavelengths and Shanghai DUV FEL [2] at visible wavelengths have confirmed that such configurations do work for single pass FELs. However, analysis of both FERMI and SINAP results indicate that the quantitative degree of planar to circular conversion can be significantly affected by several experimental details. Full conversion requires not only equal intensity of the two cross-polarized beams but also perfect overlap in space and time of their far-field amplitude and phase patterns. From both simple theoretical analysis and more detailed simulation modeling, we examine a number of possible factors that can degrade the net linear to circular conversion efficiency. In addition to the previous suggestions by Ferrari et al. of problems with unbalanced powers and transverse phase variation arising from different effective emission z locations for the two cross-polarized radiation pulses, we also consider separate degradation effects of imperfect downstream overlap of the two linearly-polarized beams arising from different emission tilt angles and mode sizes. We also discuss optimizing the conversion efficiency by aperturing the radiation pulses downstream of the undulators. [1] E. Ferrari et al., Paper THA02, Proc. FEL2013 (2013). [2] H. Deng et al., Phys. Rev. ST Accel. Beams 17, 020704 (2014).
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TUP055	Technical Overview of Bunch Compressor System for PAL XFEL	dipole, quadrupole, vacuum, electron	490
	H.-G. Lee, Y.-G. Jung, H.-S. Kang, D.E. Kim, K.W. Kim, S.B. Lee, D.H. Na, B.G. Oh, K.-H. Park, H.S. Suh, Y.J. Suh PAL, Pohang, Kyungbuk, Republic of Korea
	Pohang Accelerator Laboratory(PAL) is developing a SASE X-ray Free Electron Laser based on 10 GeV linear accelerator. Bunch compressor (BC) systems are developed to be used for the linear accelerator tunnel. It consists of three(BC1, BC2, BC3_H) hard X-ray line and one(BC3_S) soft X-ray line. BC systems are composed of four dipole magnets, three quadrupole magnet, BPM and collimator. The support system is based on an asymmetric four-dipole magnet chicane in which asymmetry and variable R56. can be optimized. This flexibility is achieved by allowing the middle two dipole magnets to move transversely. In this paper, we describe the design of the stages used for precise movement of the bunch compressor magnets and associated diagnostics components.
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TUD01	COTR Resistant Profile Monitor	electron, laser, radiation, bunching	554
	H. Loos SLAC, Menlo Park, California, USA
	Funding: Work supported by DOE contract DE-AC02-76SF00515 Electron beam accelerators used as drivers for short wavelength FELs need ultra-high brightness beams with small emittances and highly compressed bunch lengths. The acceleration and beam transport process of such beams leads to micro-bunching instabilities which cause the emergence of coherent optical transition radiation (COTR). The effect of COTR on profile monitors based on OTR or fluorescent screens can be quite detrimental to their intended use to measure beam sizes and profiles. This presentation will review past observations of the beam diagnostics issues due to COTR and discuss various mitigation schemes for profile monitors as well as present experience with such implementations.
	Slides TUD01 [1.536 MB]
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TUD02	Diffraction Radiation Monitor	electron, radiation, target, beam-diagnostic	561
	Y. Taira AIST, Tsukuba, Japan
	Non-invasive beam diagnostics using a diffraction radiation (DR) has been developed at several electron accelerator facilities. Generation process of DR is similar to that of transition radiation (TR). TR is emitted when a charged particle passes through the boundary between two media with different dielectric constants. On the other hand, DR is emitted when it passes through in the vicinity of a boundary between two media. In the generation process of DR, the charged particle doesn't intersect the medium but its electric field intersects the medium. An aperture, a slit, and an edge are used for DR target. Optical wavelength of DR is usually used for beam diagnostics. One can evaluate energy, a transverse beam size, and a divergence of an electron beam by measuring a spatial distribution of DR. Moreover, coherent diffraction radiation with the wavelength of less than millimeter range is used for a bunch length measurement. In this conference, a theoretical background of DR and experimental results carried out at several facilities will be presented.
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WEP048	Electron Beam Diagnostics for FEL Studies at CLARA	FEL, electron, laser, simulation	672
	S. Spampinati Cockcroft Institute, Warrington, Cheshire, United Kingdom D. Newton The University of Liverpool, Liverpool, United Kingdom
	CLARA (Compact Linear Accelerator for Research and Applications) is a proposed 250 MeV, 100-400 nm FEL test facility at Daresbury Laboratory [1]. The purpose of CLARA is to test and validate new FEL schemes in areas such as ultra-short pulse generation, temporal coherence and pulse-tailoring. Some of the schemes that can be tested at CLARA depend on a manipulation of the electron beam properties with characteristic scales shorter than the electron beam. In this article we describe the electron beam diagnostics required to carry on these experiments and simulations of FEL pulse and electron beam measurements. [1] J. A. Clarke et al., JINST 9, 05 (2014).
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WED03	Photon Diagnostics and Photon Beamlines Installations at the European XFEL	photon, beam-transport, radiation, vacuum	764
	J. Grünert, B. Baranasic, J. Buck, F. Dietrich, M. Dommach, W. Freund, A. Koch, N.G. Kujala, J. Liu, S. Molodtsov, M. Planas, H. Sinn XFEL. EU, Hamburg, Germany
	The European X-ray Free-Electron-Laser (XFEL. EU) is a new a 4th generation light facility which will deliver radiation with femtosecond and sub-Ångström resolution at MHz repetition rates, and is currently under construction in the Hamburg metropolitan area in Germany. Special diagnostics [1,2] for spontaneous radiation analysis is required to tune towards the lasing condition. Once lasing is achieved, diagnostic imagers [3], online monitors [4], and the photon beam transport system [5] need to cope with extreme radiation intensities. In 2015 the installation of machine equipment in the photon area of the facility is in full swing. This contribution presents the progress on final assemblies of photon diagnostics, the installation status of these devices as well as of the beam transport system, and recent design developments for diagnostic spectrometers and temporal diagnostics. [1] J. Grünert, XFEL. EU TR-2012-003(2012) [2] W. Freund, XFEL. EU TN-2014-001-01(2014) [3] A. Koch, Proc. SPIE 95121R(2015) [4] J. Buck et al., Proc. SPIE 85040U(2012) [5] H. Sinn et al., XFEL. EU TR-2012-006(2012)
	Slides WED03 [14.557 MB]
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Paper

Title

Other Keywords

Page

MOP060

RFTweak 5 - An Efficient Longitudinal Beam Dynamics Code

GUI, controls, space-charge, radiation

176

B. Beutner, H. Dinter, M. Dohlus
DESY, Hamburg, Germany

The shaping of the longitudinal phase space in bunch compression systems is essential for efficient FEL operation. RF systems and self-field interactions contribute to the overall phase space structure. The design of the various facilities relies on extensive beam dynamics simulations to define the longitudinal dynamics. However, in everyday control room applications such techniques are often not fast enough for efficient operation, e.g. for SASE tuning. Therefore efficient longitudinal beam dynamics codes are required while still maintaining reasonable accuracy. Our approach is to pre-calculate most of the required data for self-field interactions and store them on disc to reduce required online calculation time to a minimum. In this paper we present the fast longitudinal tracking code RFTweak 5, which includes wakes, space charge, and CSR interactions. With this code the full European XFEL with a 1M particles bunch is calculated on the order of minutes on a standard laptop. Neglecting CSR effects this time reduces to seconds.

Poster MOP060 [0.799 MB]

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TUP053

Real-World Considerations for Crossed-Polarized Undulator Radiation Conversion

polarization, FEL, undulator, radiation

486

W.M. Fawley, E. Allaria, E. Ferrari
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
E. Ferrari
Università degli Studi di Trieste, Trieste, Italy

Cross-polarized (X-POL) configurations are a means to produce circularly-polarized radiation output from purely planar-polarized undulators. Recent polarization results from both the FERMI FEL-1 [1] at XUV wavelengths and Shanghai DUV FEL [2] at visible wavelengths have confirmed that such configurations do work for single pass FELs. However, analysis of both FERMI and SINAP results indicate that the quantitative degree of planar to circular conversion can be significantly affected by several experimental details. Full conversion requires not only equal intensity of the two cross-polarized beams but also perfect overlap in space and time of their far-field amplitude and phase patterns. From both simple theoretical analysis and more detailed simulation modeling, we examine a number of possible factors that can degrade the net linear to circular conversion efficiency. In addition to the previous suggestions by Ferrari et al. of problems with unbalanced powers and transverse phase variation arising from different effective emission z locations for the two cross-polarized radiation pulses, we also consider separate degradation effects of imperfect downstream overlap of the two linearly-polarized beams arising from different emission tilt angles and mode sizes. We also discuss optimizing the conversion efficiency by aperturing the radiation pulses downstream of the undulators.
[1] E. Ferrari et al., Paper THA02, Proc. FEL2013 (2013).
[2] H. Deng et al., Phys. Rev. ST Accel. Beams 17, 020704 (2014).

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TUP055

Technical Overview of Bunch Compressor System for PAL XFEL

dipole, quadrupole, vacuum, electron

490

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

Pohang Accelerator Laboratory(PAL) is developing a SASE X-ray Free Electron Laser based on 10 GeV linear accelerator. Bunch compressor (BC) systems are developed to be used for the linear accelerator tunnel. It consists of three(BC1, BC2, BC3_H) hard X-ray line and one(BC3_S) soft X-ray line. BC systems are composed of four dipole magnets, three quadrupole magnet, BPM and collimator. The support system is based on an asymmetric four-dipole magnet chicane in which asymmetry and variable R56. can be optimized. This flexibility is achieved by allowing the middle two dipole magnets to move transversely. In this paper, we describe the design of the stages used for precise movement of the bunch compressor magnets and associated diagnostics components.

Export •

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

TUD01

COTR Resistant Profile Monitor

electron, laser, radiation, bunching

554

H. Loos
SLAC, Menlo Park, California, USA

Funding: Work supported by DOE contract DE-AC02-76SF00515
Electron beam accelerators used as drivers for short wavelength FELs need ultra-high brightness beams with small emittances and highly compressed bunch lengths. The acceleration and beam transport process of such beams leads to micro-bunching instabilities which cause the emergence of coherent optical transition radiation (COTR). The effect of COTR on profile monitors based on OTR or fluorescent screens can be quite detrimental to their intended use to measure beam sizes and profiles. This presentation will review past observations of the beam diagnostics issues due to COTR and discuss various mitigation schemes for profile monitors as well as present experience with such implementations.

Slides TUD01 [1.536 MB]

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TUD02

Diffraction Radiation Monitor

electron, radiation, target, beam-diagnostic

561

Y. Taira
AIST, Tsukuba, Japan

Non-invasive beam diagnostics using a diffraction radiation (DR) has been developed at several electron accelerator facilities. Generation process of DR is similar to that of transition radiation (TR). TR is emitted when a charged particle passes through the boundary between two media with different dielectric constants. On the other hand, DR is emitted when it passes through in the vicinity of a boundary between two media. In the generation process of DR, the charged particle doesn't intersect the medium but its electric field intersects the medium. An aperture, a slit, and an edge are used for DR target. Optical wavelength of DR is usually used for beam diagnostics. One can evaluate energy, a transverse beam size, and a divergence of an electron beam by measuring a spatial distribution of DR. Moreover, coherent diffraction radiation with the wavelength of less than millimeter range is used for a bunch length measurement. In this conference, a theoretical background of DR and experimental results carried out at several facilities will be presented.

Export •

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

WEP048

Electron Beam Diagnostics for FEL Studies at CLARA

FEL, electron, laser, simulation

672

S. Spampinati
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D. Newton
The University of Liverpool, Liverpool, United Kingdom

CLARA (Compact Linear Accelerator for Research and Applications) is a proposed 250 MeV, 100-400 nm FEL test facility at Daresbury Laboratory [1]. The purpose of CLARA is to test and validate new FEL schemes in areas such as ultra-short pulse generation, temporal coherence and pulse-tailoring. Some of the schemes that can be tested at CLARA depend on a manipulation of the electron beam properties with characteristic scales shorter than the electron beam. In this article we describe the electron beam diagnostics required to carry on these experiments and simulations of FEL pulse and electron beam measurements.
[1] J. A. Clarke et al., JINST 9, 05 (2014).

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WED03

Photon Diagnostics and Photon Beamlines Installations at the European XFEL

photon, beam-transport, radiation, vacuum

764

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

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

Slides WED03 [14.557 MB]

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