FLS2018 - List of Keywords (radiation)

Paper	Title	Other Keywords	Page
TUP2WD03	Turn-by-Turn Measurements for Systematic Investigations of the Micro-Bunching Instability	ion, detector, synchrotron, diagnostics	46
	J.L. Steinmann, M. Brosi, E. Bründermann, M. Caselle, S. Funkner, B. Kehrer, A.-S. Müller, M.J. Nasse, G. Niehues, L. Rota, M. Schuh, P. Schönfeldt, M. Siegel, M. Weber KIT, Karlsruhe, Germany
	Funding: Funded by the German Federal Ministry of Education and Research (Grant No. 05K16VKA) & Initiative and Networking Fund of the Helmholtz Association (contract number: VH-NG-320). While recent diffraction-limited storage rings provide bunches with transverse dimensions smaller than the wavelength of the observed synchrotron radiation, the bunch compression in the longitudinal plane is still challenging. The benefit would be single cycle pulses of coherent radiation with many orders of magnitude higher intensity. However, the self-interaction of a short electron bunch with its emitted coherent radiation can lead to micro-bunching instabilities. This effect limits the bunch compression in storage rings currently to the picosecond range. In that range, the bunches emit coherent THz radiation corresponding to their bunch length. In this paper, new measurement setups developed at the Karlsruhe Institute of Technology are described for systematic turn-by-turn investigations of the micro-bunching instability. They lead to a better understanding thereof and enable appropriate observation methods in future efforts of controlling and mastering the instability. Furthermore, the described setups might also be used as high repetition rate bunch compression monitors for bunches of picosecond length and below.
	Slides TUP2WD03 [8.524 MB]
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TUP2WD04	Preliminary Design of HEPS Storge Ring Vacuum Chambers and Components	ion, vacuum, storage-ring, photon	52
	P. He, B. Deng, D.Z. Guo, Q. Li, B.Q. Liu, Y. Ma, Y.C. Yang, L. Zhang IHEP, Beijing, People's Republic of China X.J. Wang Institute of High Energy Physics (IHEP), People's Republic of China
	In the design process of HEPS vacuum system, we meet the following limitations. Vacuum chamber must fit inside multipole magnet bore diameter of 25mm (without touching). Water channels and x-ray extraction ports must pass through a 11mm vertical pole gap. Provide an average pressure of 1nTorr during operations with 200mA beam current. Control thermal drift of BPM to ~μm and vibration amplitude ~nm level. Minimize impedance effects. This paper introduces the design of various vacuum chambers, including material selection, mechanical simulation analysis, welding test and so on.
	Slides TUP2WD04 [4.062 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUP2WD04
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TUP2WA03	Harmonic Lasing in X-Ray FELs: Theory and Experiment	ion, FEL, undulator, electron	68
	E. Schneidmiller, B. Faatz, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, M. Tischer, M.V. Yurkov DESY, Hamburg, Germany
	Harmonic lasing in XFELs is an opportunity to extend operating range of existing and planned X-ray FEL user facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental. Another interesting application of harmonic lasing is Harmonic Lasing Self-Seeded (HLSS) FEL, that allows to improve longitudinal coherence and spectral power of a SASE FEL. Recently* this concept was successfully tested at FLASH2 in the range 4.5 - 15 nm. That was also the first experimental demonstration of harmonic lasing in a high-gain FEL and at a short wavelength (before it worked only in infrared FEL oscillators). In this contribution we describe the concepts of harmonic lasing and of HLSS FEL, and present the experimental results from FLASH2. * E.Schneidmiller and M.Yurkov, Phys. Rev. ST-AB 15(2012)080702 E.Schneidmiller and M.Yurkov, Proc. of FEL2013, p.700 * E.Schneidmiller et al., Phys. Rev. Accel. Beams 20(2017)020705
	Slides TUP2WA03 [3.378 MB]
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WEA1PL02	Dielectric Accelerators and Other Non-Plasma Accelerator Based Compact Light Sources	ion, laser, undulator, electron	74
	R.J. England, Z. Huang SLAC, Menlo Park, California, USA
	Funding: U.S. Department of Energy DE-AC02-76SF00515; Gordon and Betty Moore Foundation GBMF4744 We review recent experimental progress in developing nanofabricated dielectric laser-driven accelerators and discuss the possibility of utilizing the unique sub-femtosecond electron pulse format these accelerators would provide to create ultra-compact EUV and X-ray radiation sources.
	Slides WEA1PL02 [16.828 MB]
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WEA2WD04	Harmonic Undulator Radiation with Dual Non Periodic Magnetic Components	ion, undulator, electron, FEL	98
	H. Jeevakhan NITTTR, Bhopal, India G. Mishra Devi Ahilya University, Indore, India
	Undulator radiation at third harmonics generated by harmonic undulator in the presence dual non periodic constant magnetic field. Electron trajectories along the x and y direction has been determined analytical and numerical methods. Generalized Bessel function is used to determine the intensity of radiation and Simpson's numerical method of integration is used to find the effect of constant magnetic fields. Comparison with previous analysis has also been presented.
	Slides WEA2WD04 [1.050 MB]
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WEP2PT003	Undulator Phase Matching for the the European XFEL	ion, undulator, FEL, electron	103
	Y. Li, J. Pflüger XFEL. EU, Hamburg, Germany
	The undulator system in the European XFEL is mainly comprised 5-m long undulator segments and 1.1 m long intersections in between. In intersections the electron velocity is faster than it inside an undulator and the optical phase is detuned. The detune effect is also from the undulator fringe field where electron longitudinal speed also deviates from the oscillation condition. The total detune effect is compensated by a magnetic device called phase shifter, which is correspondingly set for a specific undulator gap. In this paper we introduce the method to set the phase shifter gap for each K parameter according to the measured magnetic field.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEP2PT003
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WEP2PT022	PHASE SHIFTER APPLICATION IN DOUBLE UNDULATOR CONFIGURATION OF HEPS	ion, undulator, brilliance, electron	120
	X.Y. Li, Y. Jiao, S.K. Tian IHEP, Beijing, People's Republic of China
	For over 6 meters long straight-section of HEPS, collinear double-cryogenic permanent magnet undulator(CPMU) is designed for high energy photon users to achieve higher brightness. Angular and spatial profiles of radiation produced by the double undulator configuration have been derived analytically. The efficiency of phase shifter on improving the brightness of double-CPMU is therefore evaluated with the beam energy spread and emittance are taken into account. Optimized beta-functions of electron beam are obtained.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEP2PT022
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WEP2PT023	Preparation and Characterization of Non-Evaporable Ti-Zr-V Getter Films for HEPS	ion, vacuum, site, experiment	125
	Y. Ma, D.Z. Guo, P. He, B. Liu, Y.C. Yang IHEP, Beijing, People's Republic of China
	For the low activation temperature and high pumping speed, surface pumping capacity, the TiZrV coatings were chosen to high energy photo source (HEPS). Films of TiZrV alloy have been deposited on 1.5 meter long, cylindrical vacuum chambers of 22mm diameter copper substrates in krypton ambient using DC magnetron sputtering system. Film composition, the activation temperature and pumping properties have been investigated in order to optimize the deposition parameters for vacuum applications. The films were also studied using the X-ray photo-emission electron spectroscopy (XPS) after annealing them at different temperatures ranging from 120°C to 300°C for two hours in ultra-high vacuum environment. Pumping speed and surface pumping capacity testing facilities were also being constructed to investigate the characterization of TiZrV.
	Poster WEP2PT023 [1.037 MB]
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WEP2PT030	Undulator Development Activities at DAVV-Indore	undulator, ion, synchrotron, synchrotron-radiation	133
	M. Gehlot, R. Khullar, G. Mishra Devi Ahilya University, Indore, India H. Jeevakhan NITTTR, Bhopal, India G. Sharma RI Research Instruments GmbH, Bergisch Gladbach, Germany
	Insertion Device Design Laboratory, DAVV has development activities on in-house design, fabrication and measurement of prototype undulators for synchrotron radiation and free electron laser application. The first prototype U50 was built with six periods, 50mm each period. It was PPM type. The next prototype U20 hybrid device based on NdFeB-Cobalt steel was built with aim to produce 0.24T to 0.05T in 10-20mm gap. The undulator is a 20mm period and there are 25 periods. The next one is U50-II PPM structure with 20 periods. In this paper we review the designs of all these undulators and briefly outline the user facilities of Hall probe bench, Pulsed wire bench and stretched wire magnetic measurement systems at IDDL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEP2PT030
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THA1WA03	GPT-CSR: A New Simulation Code for CSR Effects	ion, simulation, bunching, electron	157
	S.B. van der Geer, M.J. de Loos Pulsar Physics, Eindhoven, The Netherlands I. Setija, P.W. Smorenburg ASML Netherlands B.V., Veldhoven, The Netherlands P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	For future applications of high-brightness electron beams, including the design of next generation FEL's, correct correct simulation of Coherent Synchrotron Radiation (CSR) is essential as it potentially degrades beam quality to unacceptable levels. However, the long interaction lengths compared to the bunch length, numerical cancellation, and difficult 3D retardation conditions make accurate simulation of CSR effects notoriously difficult. To ease the computational burden, CSR codes often make severe simplifications such as an ultra relativistic bunch travelling on a prescribed reference trajectory. Here we report on a new CSR model, implemented in the General Particle Tracer (GPT) code, that avoids most of the usual assumptions: It directly evaluates the Lienard-Wiechert potentials based on the stored history of the beam, it makes no assumptions about reference trajectories, while also taking into account the transverse size of the beam. First results demonstrating microbunching gain in a chicane are presented.
	Slides THA1WA03 [1.799 MB]
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THP2WB02	An Overview of the Progress on SSMB	ion, lattice, storage-ring, focusing	166
	C.-X. Tang, X.J. Deng, W.-H. Huang, T. Rui TUB, Beijing, People's Republic of China A. Chao, D.F. Ratner SLAC, Menlo Park, California, USA J. Feikes, J. Li, M. Ries HZB, Berlin, Germany C. Feng, B.C. Jiang, X.F. Wang SINAP, Shanghai, People's Republic of China E. Granados MIT, Cambridge, Massachusetts, USA A. Hoehl PTB, Berlin, Germany
	Steady State Microbunching (SSMB) is an electron stor- age ring based scheme proposed by Ratner and Chao to generate high average power coherent radiation and is one of the promising candidates to address the need of kW level EUV source for lithography. After the idea of SSMB was put forward, it has attracted much attention. Recently, with the promote of Chao, in collaboration with colleagues from other institutes, a SSMB task force has been established in Tsinghua University. The experimental proof of the SSMB principle and a feasible lattice design for EUV SSMB are the two main tasks at this moment. SSMB related physics for the formation and maintenance of microbunches will be explored in the first optical proof-of-principle experiment at the MLS storage ring in Berlin. For EUV SSMB lattice design, longitudinal strong focusing and reversible seeding are the two schemes on which the team focuses. The pro- gresses made as well as some challenges from physical and technological aspects for EUV SSMB will be presented in this paper. on behalf of the SSMB team: C. Tang, Alex Chao, X. Deng, W. Huang, and T. Rui of THU; D. Ratner of SLAC; J. Feikes and M. Ries of Helmholtz-Zentrum Berlin; C. Feng, B. Jiang, and X. Wang of SINAP
	Slides THP2WB02 [7.924 MB]
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THP2WB04	Laser Seeding of Electron Bunches for Future Ring-Based Light Sources	ion, laser, electron, storage-ring	177
	S. Khan, B. Büsing, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, B. Riemann, B. Sawadski, M. Schmutzler, P. Ungelenk DELTA, Dortmund, Germany
	Funding: Funded by BMBF (05K16PEA, 05K16PEB), MERCUR (Pr-2014-0047), DFG (INST 212/236-1 FUGG) and the Land NRW. In contrast to free-electron lasers (FELs), ring-based light sources are limited in intensity by incoherent emission and in pulse duration by the bunch length. However, FEL seeding schemes can be adopted to generate intense and ultrashort radiation pulses in storage rings by creating laser-induced microbunches within a short slice of the electron bunch. Microbunching gives rise to coherent emission at harmonics of the seed wavelength. In addition, terahertz (THz) radiation is coherently emitted over many turns. At DELTA, a storage ring operated by the TU Dortmund University, coherent harmonic generation (CHG) with single and double 40-fs pulses is routinely performed at seed wavelengths of 800 and 400 nm. Seeding with intensity-modulated pulses to generate tunable narrowband THz radiation is also studied. As a preparation for echo-enabled harmonic generation (EEHG), simultaneous seeding with 800/400-nm pulses in two undulators has been demonstrated. The DELTA storage ring is an excellent testbed to study many aspects of laser seeding and related diagnostics. In addition to short-pulse generation, steady-state microbunching at ring-based light sources will be discussed in the paper.
	Slides THP2WB04 [5.103 MB]
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THP1WD02	LCLS-II Beam Containment System for Radiation Safety	ion, electron, cavity, FEL	187
	C.I. Clarke, J. Bauer, M. Boyes, Y. Feng, A.S. Fisher, R.A. Kadyrov, J.C. Liu, E. Rodriguez, M. Rowen, M. Santana-Leitner, F. Tao, J.J. Welch, S. Xiao SLAC, Menlo Park, California, USA T.L. Allison, J. Musson JLab, Newport News, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515 and DE-AC05-06OR23177. LCLS-II is a new xFEL facility under construction at SLAC National Accelerator Laboratory with a superconducting electron linac designed to operate up to §I{1.2}{MW} of beam power. This generates more serious beam hazards than the typical sub-kW linac operation of the existing xFEL facility, Linac Coherent Light Source (LCLS). SLAC uses a set of safety controls termed the Beam Containment System (BCS) to limit beam power and losses to prevent excessive radiation in occupied areas. The high beam power hazards of LCLS-II necessitate the development of new BCS devices and a larger scale deployment than previously done at LCLS. We present the new radiation hazards introduced by LCLS-II and the design development for the BCS.
	Slides THP1WD02 [2.244 MB]
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Paper

Title

Other Keywords

Page

TUP2WD03

Turn-by-Turn Measurements for Systematic Investigations of the Micro-Bunching Instability

ion, detector, synchrotron, diagnostics

46

J.L. Steinmann, M. Brosi, E. Bründermann, M. Caselle, S. Funkner, B. Kehrer, A.-S. Müller, M.J. Nasse, G. Niehues, L. Rota, M. Schuh, P. Schönfeldt, M. Siegel, M. Weber
KIT, Karlsruhe, Germany

Funding: Funded by the German Federal Ministry of Education and Research (Grant No. 05K16VKA) & Initiative and Networking Fund of the Helmholtz Association (contract number: VH-NG-320).
While recent diffraction-limited storage rings provide bunches with transverse dimensions smaller than the wavelength of the observed synchrotron radiation, the bunch compression in the longitudinal plane is still challenging. The benefit would be single cycle pulses of coherent radiation with many orders of magnitude higher intensity. However, the self-interaction of a short electron bunch with its emitted coherent radiation can lead to micro-bunching instabilities. This effect limits the bunch compression in storage rings currently to the picosecond range. In that range, the bunches emit coherent THz radiation corresponding to their bunch length. In this paper, new measurement setups developed at the Karlsruhe Institute of Technology are described for systematic turn-by-turn investigations of the micro-bunching instability. They lead to a better understanding thereof and enable appropriate observation methods in future efforts of controlling and mastering the instability. Furthermore, the described setups might also be used as high repetition rate bunch compression monitors for bunches of picosecond length and below.

Slides TUP2WD03 [8.524 MB]

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TUP2WD04

Preliminary Design of HEPS Storge Ring Vacuum Chambers and Components

ion, vacuum, storage-ring, photon

52

P. He, B. Deng, D.Z. Guo, Q. Li, B.Q. Liu, Y. Ma, Y.C. Yang, L. Zhang
IHEP, Beijing, People's Republic of China
X.J. Wang
Institute of High Energy Physics (IHEP), People's Republic of China

In the design process of HEPS vacuum system, we meet the following limitations. Vacuum chamber must fit inside multipole magnet bore diameter of 25mm (without touching). Water channels and x-ray extraction ports must pass through a 11mm vertical pole gap. Provide an average pressure of 1nTorr during operations with 200mA beam current. Control thermal drift of BPM to ~μm and vibration amplitude ~nm level. Minimize impedance effects. This paper introduces the design of various vacuum chambers, including material selection, mechanical simulation analysis, welding test and so on.

Slides TUP2WD04 [4.062 MB]

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TUP2WA03

Harmonic Lasing in X-Ray FELs: Theory and Experiment

ion, FEL, undulator, electron

68

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

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

Slides TUP2WA03 [3.378 MB]

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WEA1PL02

Dielectric Accelerators and Other Non-Plasma Accelerator Based Compact Light Sources

ion, laser, undulator, electron

74

R.J. England, Z. Huang
SLAC, Menlo Park, California, USA

Funding: U.S. Department of Energy DE-AC02-76SF00515; Gordon and Betty Moore Foundation GBMF4744
We review recent experimental progress in developing nanofabricated dielectric laser-driven accelerators and discuss the possibility of utilizing the unique sub-femtosecond electron pulse format these accelerators would provide to create ultra-compact EUV and X-ray radiation sources.

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WEA2WD04

Harmonic Undulator Radiation with Dual Non Periodic Magnetic Components

ion, undulator, electron, FEL

98

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

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

Slides WEA2WD04 [1.050 MB]

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WEP2PT003

Undulator Phase Matching for the the European XFEL

ion, undulator, FEL, electron

103

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

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

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WEP2PT022

PHASE SHIFTER APPLICATION IN DOUBLE UNDULATOR CONFIGURATION OF HEPS

ion, undulator, brilliance, electron

120

X.Y. Li, Y. Jiao, S.K. Tian
IHEP, Beijing, People's Republic of China

For over 6 meters long straight-section of HEPS, collinear double-cryogenic permanent magnet undulator(CPMU) is designed for high energy photon users to achieve higher brightness. Angular and spatial profiles of radiation produced by the double undulator configuration have been derived analytically. The efficiency of phase shifter on improving the brightness of double-CPMU is therefore evaluated with the beam energy spread and emittance are taken into account. Optimized beta-functions of electron beam are obtained.

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WEP2PT023

Preparation and Characterization of Non-Evaporable Ti-Zr-V Getter Films for HEPS

ion, vacuum, site, experiment

125

Y. Ma, D.Z. Guo, P. He, B. Liu, Y.C. Yang
IHEP, Beijing, People's Republic of China

For the low activation temperature and high pumping speed, surface pumping capacity, the TiZrV coatings were chosen to high energy photo source (HEPS). Films of TiZrV alloy have been deposited on 1.5 meter long, cylindrical vacuum chambers of 22mm diameter copper substrates in krypton ambient using DC magnetron sputtering system. Film composition, the activation temperature and pumping properties have been investigated in order to optimize the deposition parameters for vacuum applications. The films were also studied using the X-ray photo-emission electron spectroscopy (XPS) after annealing them at different temperatures ranging from 120°C to 300°C for two hours in ultra-high vacuum environment. Pumping speed and surface pumping capacity testing facilities were also being constructed to investigate the characterization of TiZrV.

Poster WEP2PT023 [1.037 MB]

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WEP2PT030

Undulator Development Activities at DAVV-Indore

undulator, ion, synchrotron, synchrotron-radiation

133

M. Gehlot, R. Khullar, G. Mishra
Devi Ahilya University, Indore, India
H. Jeevakhan
NITTTR, Bhopal, India
G. Sharma
RI Research Instruments GmbH, Bergisch Gladbach, Germany

Insertion Device Design Laboratory, DAVV has development activities on in-house design, fabrication and measurement of prototype undulators for synchrotron radiation and free electron laser application. The first prototype U50 was built with six periods, 50mm each period. It was PPM type. The next prototype U20 hybrid device based on NdFeB-Cobalt steel was built with aim to produce 0.24T to 0.05T in 10-20mm gap. The undulator is a 20mm period and there are 25 periods. The next one is U50-II PPM structure with 20 periods. In this paper we review the designs of all these undulators and briefly outline the user facilities of Hall probe bench, Pulsed wire bench and stretched wire magnetic measurement systems at IDDL.

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THA1WA03

GPT-CSR: A New Simulation Code for CSR Effects

ion, simulation, bunching, electron

157

S.B. van der Geer, M.J. de Loos
Pulsar Physics, Eindhoven, The Netherlands
I. Setija, P.W. Smorenburg
ASML Netherlands B.V., Veldhoven, The Netherlands
P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

For future applications of high-brightness electron beams, including the design of next generation FEL's, correct correct simulation of Coherent Synchrotron Radiation (CSR) is essential as it potentially degrades beam quality to unacceptable levels. However, the long interaction lengths compared to the bunch length, numerical cancellation, and difficult 3D retardation conditions make accurate simulation of CSR effects notoriously difficult. To ease the computational burden, CSR codes often make severe simplifications such as an ultra relativistic bunch travelling on a prescribed reference trajectory. Here we report on a new CSR model, implemented in the General Particle Tracer (GPT) code, that avoids most of the usual assumptions: It directly evaluates the Lienard-Wiechert potentials based on the stored history of the beam, it makes no assumptions about reference trajectories, while also taking into account the transverse size of the beam. First results demonstrating microbunching gain in a chicane are presented.

Slides THA1WA03 [1.799 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-THA1WA03

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THP2WB02

An Overview of the Progress on SSMB

ion, lattice, storage-ring, focusing

166

C.-X. Tang, X.J. Deng, W.-H. Huang, T. Rui
TUB, Beijing, People's Republic of China
A. Chao, D.F. Ratner
SLAC, Menlo Park, California, USA
J. Feikes, J. Li, M. Ries
HZB, Berlin, Germany
C. Feng, B.C. Jiang, X.F. Wang
SINAP, Shanghai, People's Republic of China
E. Granados
MIT, Cambridge, Massachusetts, USA
A. Hoehl
PTB, Berlin, Germany

Steady State Microbunching (SSMB) is an electron stor- age ring based scheme proposed by Ratner and Chao to generate high average power coherent radiation and is one of the promising candidates to address the need of kW level EUV source for lithography. After the idea of SSMB was put forward, it has attracted much attention. Recently, with the promote of Chao, in collaboration with colleagues from other institutes, a SSMB task force has been established in Tsinghua University. The experimental proof of the SSMB principle and a feasible lattice design for EUV SSMB are the two main tasks at this moment. SSMB related physics for the formation and maintenance of microbunches will be explored in the first optical proof-of-principle experiment at the MLS storage ring in Berlin. For EUV SSMB lattice design, longitudinal strong focusing and reversible seeding are the two schemes on which the team focuses. The pro- gresses made as well as some challenges from physical and technological aspects for EUV SSMB will be presented in this paper.
on behalf of the SSMB team: C. Tang, Alex Chao, X. Deng, W. Huang, and T. Rui of THU; D. Ratner of SLAC; J. Feikes and M. Ries of Helmholtz-Zentrum Berlin; C. Feng, B. Jiang, and X. Wang of SINAP

Slides THP2WB02 [7.924 MB]

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THP2WB04

Laser Seeding of Electron Bunches for Future Ring-Based Light Sources

ion, laser, electron, storage-ring

177

S. Khan, B. Büsing, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, B. Riemann, B. Sawadski, M. Schmutzler, P. Ungelenk
DELTA, Dortmund, Germany

Funding: Funded by BMBF (05K16PEA, 05K16PEB), MERCUR (Pr-2014-0047), DFG (INST 212/236-1 FUGG) and the Land NRW.
In contrast to free-electron lasers (FELs), ring-based light sources are limited in intensity by incoherent emission and in pulse duration by the bunch length. However, FEL seeding schemes can be adopted to generate intense and ultrashort radiation pulses in storage rings by creating laser-induced microbunches within a short slice of the electron bunch. Microbunching gives rise to coherent emission at harmonics of the seed wavelength. In addition, terahertz (THz) radiation is coherently emitted over many turns. At DELTA, a storage ring operated by the TU Dortmund University, coherent harmonic generation (CHG) with single and double 40-fs pulses is routinely performed at seed wavelengths of 800 and 400 nm. Seeding with intensity-modulated pulses to generate tunable narrowband THz radiation is also studied. As a preparation for echo-enabled harmonic generation (EEHG), simultaneous seeding with 800/400-nm pulses in two undulators has been demonstrated. The DELTA storage ring is an excellent testbed to study many aspects of laser seeding and related diagnostics. In addition to short-pulse generation, steady-state microbunching at ring-based light sources will be discussed in the paper.

Slides THP2WB04 [5.103 MB]

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THP1WD02

LCLS-II Beam Containment System for Radiation Safety

ion, electron, cavity, FEL

187

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

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

Slides THP1WD02 [2.244 MB]

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