IPAC2013 - List of Keywords (wiggler)

Paper	Title	Other Keywords	Page
MOZB102	Undulator Technologies for Future Free Electron Laser Facilities and Storage Rings	undulator, vacuum, radiation, electron	26
	M.-E. Couprie SOLEIL, Gif-sur-Yvette, France
	Insertion devices (undulators and wigglers) are key components for high brightness third generation synchrotron sources and for the amplifying medium of free electron lasers. Different technological developments carried out worldwide lead to improved undulator performance. In particular, the advances concerning the in vacuum permanent magnet systems, in particular for short period ones with the operation at cryogenic temperature with NdFeB or PrFeB magnets or for long period ones where in vacuum wigglers will be described. Secondly, progress in Elliptical Polarised Undulators (EPU) will be discussed, such as the DELTA undulator. Recent progress in superconducting undulators will also be reported. Finally, the effect of the insertion devices on the light source operation is analysed, either with the strategies to compensate unwanted effects or in viewing taking advantage of them as for Robinson or damping wigglers for reducing storage ring horizontal emittance.
	Slides MOZB102 [8.940 MB]

MOPEA038	Coherent Wiggler Radiation of Picosecond CW Electron Beam Produced by DC-SRF Photoinjector	radiation, electron, SRF, acceleration	160
	S. Huang, J.E. Chen, S. Chen, K.X. Liu, S.W. Quan, Zh.W. Wang, X.D. Wen, F. Zhu PKU, Beijing, People's Republic of China
	The DC-SRF photoinjector at Peking University is capable of providing CW electron beam with the energy of 3-5 MeV. The beam has high repetition rate, picosecond bunch length and high quality, which can be used to produce high repetition rate THz wave by wiggler radiation. Through off-crest acceleration, electron beam from the injector may be bunched, which will lead to coherent enhancement of the radiation power. With current setup of the DC-SRF injector and a 10-period wiggler, THz radiation power of 10s mW to a few watts can be achieved within the wavelength range of 200 μm to 500 μm. In this work, we will present the calculation results about THz radiation produced by the electron beam from DC-SRF photoinjector. The preparation for the experiments will be also described.

MOPEA051	Insertion Devices Influence on the Beam Dynamics at Siberia-2 Storage Ring	dynamic-aperture, undulator, insertion, insertion-device	193
	S.I. Tomin, V. Korchuganov NRC, Moscow, Russia
	Siberia-2 is now running with 7.5 T wiggler and the installation of additional two 3 T SC wigglers is under consideration. Besides that the insertion of an undulator with very short period up to 7 mm is planed. We studied an influence of the insertion devices on the dynamic aperture using new computer code which permits to find an electron beam trajectory in ID by Runge-Kutta integrator. Using two independent approaches it was shown that ID introduces the nonlinear components of magnetic field which lead to significant decrease of dynamic aperture in vertical direction. Nonlinear components of ID magnetic field are shown. Results of numerical calculation of Siberia-2 dynamic aperture are presented as well.

MOPEA066	Investigation and Test of the Possibility of Reducing the Emittance of the Diamond Storage Ring	emittance, optics, lattice, injection	234
	B. Singh, M. Apollonio, R. Bartolini, E.C. Longhi Diamond, Oxfordshire, United Kingdom R. Bartolini, T. Pulampong JAI, Oxford, United Kingdom
	Theoretical and experimental studies have been carried out at the Diamond Light Source to assess the possibility of reducing the emittance of the existing storage ring by means of a change to the optics. The optics solutions obtained so far using a Multi Objective Genetic Algorithm (MOGA) increase the dispersion and the horizontal beta function in the straight section. While the emittance can be reduced to 2.1 nm this optics is limited by the operation of high field superconducting wiggler devices. In this report we present details of the new optics and present results of practical tests. We also compare the theoretical emittance growth due to a wiggler in a dispersive region with test results.

MOPEA077	Accelerator Physics and Light Source Research Program at Duke University	FEL, storage-ring, electron, feedback	264
	Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. he accelerator physics and light source research program at Duke Free-Electron Laser Laboratory (DFELL), TUNL, is focused on the development of the storage ring based free-electron lasers (FELs), and a state-of-the-art Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS). Driven by the storage ring FEL, the HIGS is world's most intense Compton gamma-ray source with a maximum total flux of few 10¹⁰ gamma per second (around 10 MeV). Operated in the energy range from 1 to 100 MeV, the HIGS is a premier nuclear physics research facility in the world. In 2012, we completed a major accelerator upgrade project with a wiggler switchyard system which allows the configuration changes between planar and helical FEL wigglers, and a great enhancement of the FEL gain when operated with 3 or 4 helical wigglers. In this paper, we will describe our ongoing light source development to produce gamma-ray beams in the new energy range of 100 and 158 MeV. We will also provide a summary of our accelerator physics research activities in the area of nonlinear dynamics, beam instability research, and FEL research.

MOPEA078	Commissioning and Operation of Wiggler Switchyard System for Duke FEL and HIGS	FEL, vacuum, storage-ring, lattice	267
	Y.K. Wu, M.D. Busch, M. Emamian, J.F. Faircloth, H. Hao, J.Y. Li, S.F. Mikhailov, V. Popov, G. Swift, P.W. Wallace, P. Wang, J. Yan FEL/Duke University, Durham, North Carolina, USA A.L. Wu USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. To enable the Duke storage ring FEL to operate in VUV with adequate gain, a major storage ring upgrade was carried out in 2012 to install two additional helical FEL wigglers with a wiggler switchyard system. Using the switchyard, a quick changeover can be made between two planar OK-4 wigglers and two helical OK-5 wigglers in the middle of the FEL straight section. This system preserves the linear polarization capabilities of the Duke FEL and gamma-ray beams at the High Intensity Gamma-ray Source (HIGS), while enabling VUV FEL operation with a higher gain using a longer FEL with as many as four helical wigglers. The wiggler switchyard upgrade was completed in Summer 2012, followed by a rapid and successful commissioning of the Duke storage ring, FEL system, and HIGS. In this paper, we will present the results of accelerator and light source commissioning with the wiggler switchyard. We will also present preliminary results of operating the OK-5 FEL in different configurations. With the wiggler switchyard, we are well positioned to realize the operation of a VUV FEL below 190 nm and production of Compton gamma-ray beams above 100 MeV in circular polarization.

TUODB102	Intrabeam Scattering Studies for Low Emittance of BAPS	emittance, damping, storage-ring, lattice	1123
	S.K. Tian, Y. Jiao, J.Q. Wang, G. Xu IHEP, Beijing, People's Republic of China
	In modern storage ring light sources, intra-beam scattering (IBS) is often thought of as a fundamental limitation to achieving ultra-low emittance and hence higher brightness. Beijing Advanced Photon Source (BAPS) is under design at Institute of High Energy Physics (IHEP) which aims to emittance less than 1nm at 5GeV. To improve the coherence and high brightness, low emittance- in both transverse planes at the diffraction limit for the range of x-ray wavelengths(≈10 pm)- is being pursued. Thus, due to the very low emittance, intra-beam scattering effect is an issue. Accurate estimation to check if the design goal can be reached is necessary. In this paper, we use the 6-D accelerator simulation code-elegant and Accelerator Toolbox (AT)-a collection of tools to model storage rings in the MATLAB environment. Based on a temporary design lattice of BAPS, we present the results of particle simulation study of intra-beam scattering effect versus the beam energy, the emittance coupling factor, the bunch length, the bunch current and so on. We also studied the mitigating method by adopting damping wigglers in one or more dispersion-free regions.
	Slides TUODB102 [2.338 MB]

TUPEA074	Protection of VUV FEL Mirrors using Soft Orbit Bump at Duke FEL/HIGS facility	FEL, radiation, electron, dipole	1301
	S.F. Mikhailov, H. Hao, J.Y. Li, V. Popov, P.W. Wallace, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DoE grant # DE-FG02-97ER41033 The Duke FEL and High Intensity Gamma-ray Source (HIGS) facility is operated with an electron beam from 0.24 to 1.2 GeV and a photon beam from 190 to 1060 nm. Presently, the energy range of the gamma-beam is from 1 MeV to about 100 MeV, with the maximum total gamma-flux of more then 10¹⁰ gammas per second around 10 MeV. Production of high intensity, high energy gamma-beams of 60 to 100 MeV, using UV-VUV mirrors of 240 to 190 nm, requires high energy, high current electron beams of 0.9 to 1.05 GeV. Synchrotron radiation damage to the FEL mirrors becomes crucial for VUV FEL operation at or below 190 nm. The edge radiation (ER) from the End-of-Arc (EOA) bending magnet, instead of the radiation of FEL wigglers, is the dominant cause of a rapid degradation of the downstream FEL mirror. In this work, we describe a further development of the “soft” orbit bump concept to significantly reduce the radiation exposure to the mirror from the EOA dipole magnet. The bump uses designated "soft" orbit correctors with magnetic field limited to produce a radiation with a critical wavelength close or below the FEL wavelength.

TUPME005	Preparations for Beam Tests of a CLIC Damping Wiggler Prototype at ANKA	damping, emittance, target, storage-ring	1568
	A. Bernhard, E. Huttel, P. Peiffer KIT, Karlsruhe, Germany A.V. Bragin, N.A. Mezentsev, V.M. Syrovatin, K. Zolotarev BINP SB RAS, Novosibirsk, Russia P. Ferracin, D. Schoerling CERN, Geneva, Switzerland
	The Compact Linear Collider (CLIC) will require ultra-low emittance electron and positron beams. The targeted emittance will be achieved by radiative damping in the CLIC damping rings. For an efficient damping high-field short-period superconducting damping wigglers will be employed. In the conceptual design phase of CLIC, the basic layout of these wigglers has been elaborated at CERN. In the course of the CLIC technical feasibility studies a full-scale damping wiggler prototype will be installed and tested in the ANKA storage ring. The device is currently under design and construction at the Budker Institute of Nuclear Physics, Russia. Above the magnetic requirements, the main design challenges for the prototype are scalability –- particularly of the cooling concept –-, modularity and the capability of sustaining a high radiative heat load. The experiments at ANKA aim at a validation of the technical concepts applied to meet these requirements. Beyond that an extended experimental program on beam dynamics and alternative technical solutions is envisaged. This contribution gives an overview over the current status of the project and the further planning.

TUPME022	Study on the Single Bunch Transverse Emittance Growth in BAPS	emittance, wakefield, lattice, vacuum	1619
	J. Gao, D. Wang IHEP, Beijing, People's Republic of China
	Funding: Supported by the National Foundation of Natural Sciences Contract 11175192. Beijing Advanced photon Source (BAPS) is a proposed next synchrotron radiation facility which has much smaller transverse emittance after SSRF in China, with 5 GeV energy and 1.5 km circumference. In order to explore how small the transverse emittance we can get on BAPS, this paper studies the single bunch transverse emittance growth due to short range wakefield according to J. Gao’ theory. The mechanism of wakefield induced single bunch emittance is explained first and then the transverse emittance at the design beam current is estimated. Also, the tolerances for the transverse loss factor and the vacuum chamber misalignment (or the closed orbit distortion) are presented.

TUPME040	TLEP: High-performance Circular e⁺e⁻ Collider to Study the Higgs Boson	polarization, luminosity, cryogenics, collider	1658
	M. Koratzinos, O. Brunner, A.C. Butterworth, J.R. Ellis, P. Janot, E. Jensen, J.A. Osborne, F. Zimmermann CERN, Geneva, Switzerland R. Aleksan CEA/DSM/IRFU, France A.P. Blondel DPNC, Genève, Switzerland M. Zanetti MIT, Cambridge, Massachusetts, USA
	The recent discovery of a light Higgs boson has opened up considerable interest in circular e⁺e⁻ Higgs factories around the world. We report on the progress of the “TLEP3” concept since last year. Two options are considered: LEP3, a 240 GeV centre-of-mass (Ecm) e⁺e⁻ machine in the LHC tunnel with cost only a fraction of the cost of an equivalent linear collider, due to the use of existing infrastructure and the two general-purpose LHC detectors, and TLEP, an e⁺e⁻ machine in a new 80 km tunnel that can operate up to an Ecm of 350 GeV. Both concepts enjoy the extensive know-how on circular colliders and how to deliver their design luminosity, and the existence of up to four interaction points. The attainable luminosities are 10³⁴/cm²/s and 5x10³⁴/cm²/s per interaction point for LEP3 and TLEP respectively. Both machines can operate as Tera-Z and Mega-W boson factories, giving decisive opportunities for over-constraining the electroweak sector of the Standard Model. The technical challenges and possible ways to improve the performance further will be discussed.

TUPME042	The SPS as an Ultra-low Emittance Damping Ring Test Facility for CLIC	damping, emittance, optics, target	1661
	Y. Papaphilippou, R. Corsini, L.R. Evans CERN, Geneva, Switzerland
	In view of the plans for a future electron/positron linear collider based on the CLIC technology, an ultra-low emittance damping ring test facility is proposed, using the CERN SPS. Optics modification, required wiggler length and characteristics, energy and RF parameters are presented in order to reach CLIC performance requirements, including the effect of Intrabeam Scattering. Considerations about the necessary injected beam characteristics, its production and transfer through the existing CERN accelerator complex are also discussed.

TUPME066	CESR Low Emittance Upgrade with Combined Function Bends	quadrupole, emittance, damping, focusing	1718
	D. L. Rubin, Y. Li, A.A. Mikhailichenko, S. Wang CLASSE, Ithaca, New York, USA
	Funding: Work supported by the National Science Foundation and Department of Energy under contract numbers PHY-1002467, DMR-0936384 and DE-SC0006505 The Cornell Electron Storage Ring is the laboratory for the CESR Test Accelerator damping ring R&D program, and the source of x-rays for CHESS. A peculiarity of the layout of the storage ring is that horizontal emittance is generated predominantly by the strong bends in the sextant of the ring that was designed with a long straight to accommodate the interaction region required for operation as an electron-positron collider. By reconfiguring that single sextant we reduce the emittance by 60% to 20 nm-rad at 5.3 GeV for x-ray production and with damping wigglers to 1.3 nm-rad at 2.1 GeV for investigations of low emittance phenomena. The 35 meter radius of curvature, 3.2 meter long dipoles are refitted as combined function (vertically focusing) magnets to create simple achromats. The layout can accommodate six, 3 meter long undulators, in addition to the six existing superconducting damping wigglers. With reduced horizontal emittance and energy spread, the reconfiguration enhances the sensitivity of CESR to the emittance diluting effects that are the subject of the CesrTA study. Capability of the x-ray source is significantly improved with six new undulator beam lines.

TUPWA052	Loss Factor and Impedance Analysis for the Diamond Storage Ring	impedance, storage-ring, vacuum, simulation	1826
	R. Bartolini, R.T. Fielder, C.A. Thomas Diamond, Oxfordshire, United Kingdom
	Diamond Light Source is investigating the possibility of increasing the storage ring operating current above the nominal 300 mA. A campaign of measurements and simulations has been carried out in order to understand the extent of the parasitic energy loss and characterise the most important items which build up the machine impedance. In this paper we report on the most recent measurements of the longitudinal loss factor and the present status of the impedance database with an initial comparison between the two.

TUPWA071	Studies of Resistive Wall Heating at JLAB FEL	impedance, FEL, resonance, electron	1868
	R. Li, S.V. Benson JLAB, Newport News, Virginia, USA
	Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. When the JLAB FEL is under CW operation, it had been observed that temperature rises over the wiggler vacuum chamber, presumably as the result of the power deposition on the resistive wall of the wiggler chamber. Previous analyses have been done on the resistive wall impedance for various cases, such as DC, AC, and anomalous skin effects. Here we report an investigation on the beam kinetic energy losses for each of these cases. This study includes the non-ultrarelativistic effect on resistive wall loss, for both round pipe and parallel plates. We will present the comparison of our results with the measured data obtained during CW operation of the JLAB FEL. Other possible factors contributing to the measured heating will also be discussed. K. Bane and G. Stupakov, SLAC-PUB-10707, 2004.

TUPWO063	Reducing HLS-II Emittance by Radiation Damping Partition Factor Exchange	emittance, storage-ring, damping, lattice	2009
	J.Y. Li FEL/Duke University, Durham, North Carolina, USA W. Li, G. Liu, W. Xu USTC/NSRL, Hefei, Anhui, People's Republic of China Y. Li BNL, Upton, Long Island, New York, USA
	Funding: The Introduction of Outstanding Technological Talents Program of Chinese Academy of Sciences, 2010. In this paper, we present a preliminary study on using a Robinson wiggler, a wiggler with transverse gradient, to reduce the horizontal beam emittance of the Hefei Light Source II (HLS-II) storage ring. A proof-of-principle study demonstrates that it is possible to further reduce the horizontal beam emittance by 50\% using a 2-meter long Robinson wiggler installed on a dispersive straight section. This encouraging result suggests a feasible option to significantly improve the HLS-II performance at a relative low cost and without significant modification to its global configuration in the near future.

WEPWA001	Wigglers at Danfysik	electron, damping, radiation, emittance	2123
	C.W.O. Ostenfeld, M. Pedersen Danfysik A/S, Taastrup, Denmark
	In the past 2 years, a number of insertion devices have been designed, assembled and tested at Danfysik. They are used for a variety of applications at free electron lasers and synchrotron radiation facilities. In this paper, we highlight 3 different wiggler projects: A 2.0 T wiggler for Astrid-II in Århus, Denmark, a fixed-gap electromagnetic wiggler for Helmholtz Center Dresden-Rossendorf, and 6 identical damping wigglers for NSLS-2 at Brookhaven National Laboratory (BNL). For the Astrid-2 facility in Aarhus, Denmark, we have designed and built a 6 period wiggler, with a peak field of 2.0 T. The magnetic design and performance is presented and discussed. As part of the ELBE THz facility, at Helmholtz Center Dresden-Rossendorf, we have designed and built a fixed-gap electromagnetic wiggler, with 300 mm period length, and a peak field of 0.39 T. We present the design and magnetic results. For the NSLS-2 project at BNL, damping wigglers are an integral part of the design, both as a means of reducing the emittance, but also as a source of intense radiation sources for users. We present the mechanical and magnetic design, as well as magnetic results obtained for the wigglers.

WEPME038	Slow Orbit Feedback and Beam Stability at ALBA	photon, injection, electron, feedback	3010
	J. Marcos, M. Muñoz CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	ALBA is a 3GeV 3rd generation synchrotron radiation source built nearby Barcelona providing service to users since May 2012. During all this period, a Slow Orbit Feedback system (SOFB) has been running during users’ operation in order to deliver a stable photon beam to the Beamlines. The system employs 88 out of the 10⁴ Beam Position Monitors (BPMs) available at ALBA and 88 horizontal and vertical correctors. In addition, since the middle of the year (July 2012), the reading of the X-Ray BPM (XBPM) for one of the Front Ends, with a Bending Magnet as a source, has also been included in the correction loop. In this paper we summarize the performance of the SOFB system. Besides, we also present data corresponding to the evolution along the year of the XBPM readings for several Front Ends that have a planar Insertion Device (ID) as a source. The analyzed XBPMs are not included in the orbit correction loop, and consequently they supply information regarding the long term stability of ALBA Storage Ring.

THPEA057	Compensation Schemes for Operation of FEL Wigglers on Duke Storage Ring	FEL, storage-ring, lattice, quadrupole	3270
	J.Y. Li, H. Hao, S.F. Mikhailov, V. Popov, W. Wu, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. The Duke FEL is the photon driver for the High Intensity Gamma-ray Source (HIGS). To extend the capabilities of the FEL and HIGS to higher photon energy regions, a FEL wiggler switchyard system was developed in the recent years. This system was installed and commissioned in 2012. The FEL wiggler switchyard is used to change between two planar OK-4 wigglers and two helical OK-5 wigglers in the middle of the FEL straight section in a short period of time (a few days). With a total of six electromagnetic wigglers, the Duke FEL can be operated in a number of wiggler configurations and with a wide range of magnetic fields. The operation of uncompensated FEL wigglers can cause significant changes to the electron beam closed orbit and magnetic lattice. To maintain a sufficiently large dynamic aperture for an efficient injection and good beam lifetime, a set of complex compensation schemes, including magnetic field and lattice compensation, have been developed for the operation of the FEL wigglers. This paper reports the overall architecture and performance of the FEL wiggler compensation schemes and their implementation in the accelerator controls system using the feedforward mechanism.

Paper

Title

Other Keywords

Page

MOZB102

Undulator Technologies for Future Free Electron Laser Facilities and Storage Rings

undulator, vacuum, radiation, electron

26

M.-E. Couprie
SOLEIL, Gif-sur-Yvette, France

Insertion devices (undulators and wigglers) are key components for high brightness third generation synchrotron sources and for the amplifying medium of free electron lasers. Different technological developments carried out worldwide lead to improved undulator performance. In particular, the advances concerning the in vacuum permanent magnet systems, in particular for short period ones with the operation at cryogenic temperature with NdFeB or PrFeB magnets or for long period ones where in vacuum wigglers will be described. Secondly, progress in Elliptical Polarised Undulators (EPU) will be discussed, such as the DELTA undulator. Recent progress in superconducting undulators will also be reported. Finally, the effect of the insertion devices on the light source operation is analysed, either with the strategies to compensate unwanted effects or in viewing taking advantage of them as for Robinson or damping wigglers for reducing storage ring horizontal emittance.

Slides MOZB102 [8.940 MB]

MOPEA038

Coherent Wiggler Radiation of Picosecond CW Electron Beam Produced by DC-SRF Photoinjector

radiation, electron, SRF, acceleration

160

S. Huang, J.E. Chen, S. Chen, K.X. Liu, S.W. Quan, Zh.W. Wang, X.D. Wen, F. Zhu
PKU, Beijing, People's Republic of China

The DC-SRF photoinjector at Peking University is capable of providing CW electron beam with the energy of 3-5 MeV. The beam has high repetition rate, picosecond bunch length and high quality, which can be used to produce high repetition rate THz wave by wiggler radiation. Through off-crest acceleration, electron beam from the injector may be bunched, which will lead to coherent enhancement of the radiation power. With current setup of the DC-SRF injector and a 10-period wiggler, THz radiation power of 10s mW to a few watts can be achieved within the wavelength range of 200 μm to 500 μm. In this work, we will present the calculation results about THz radiation produced by the electron beam from DC-SRF photoinjector. The preparation for the experiments will be also described.

MOPEA051

Insertion Devices Influence on the Beam Dynamics at Siberia-2 Storage Ring

dynamic-aperture, undulator, insertion, insertion-device

193

S.I. Tomin, V. Korchuganov
NRC, Moscow, Russia

Siberia-2 is now running with 7.5 T wiggler and the installation of additional two 3 T SC wigglers is under consideration. Besides that the insertion of an undulator with very short period up to 7 mm is planed. We studied an influence of the insertion devices on the dynamic aperture using new computer code which permits to find an electron beam trajectory in ID by Runge-Kutta integrator. Using two independent approaches it was shown that ID introduces the nonlinear components of magnetic field which lead to significant decrease of dynamic aperture in vertical direction. Nonlinear components of ID magnetic field are shown. Results of numerical calculation of Siberia-2 dynamic aperture are presented as well.

MOPEA066

Investigation and Test of the Possibility of Reducing the Emittance of the Diamond Storage Ring

emittance, optics, lattice, injection

234

B. Singh, M. Apollonio, R. Bartolini, E.C. Longhi
Diamond, Oxfordshire, United Kingdom
R. Bartolini, T. Pulampong
JAI, Oxford, United Kingdom

Theoretical and experimental studies have been carried out at the Diamond Light Source to assess the possibility of reducing the emittance of the existing storage ring by means of a change to the optics. The optics solutions obtained so far using a Multi Objective Genetic Algorithm (MOGA) increase the dispersion and the horizontal beta function in the straight section. While the emittance can be reduced to 2.1 nm this optics is limited by the operation of high field superconducting wiggler devices. In this report we present details of the new optics and present results of practical tests. We also compare the theoretical emittance growth due to a wiggler in a dispersive region with test results.

MOPEA077

Accelerator Physics and Light Source Research Program at Duke University

FEL, storage-ring, electron, feedback

264

Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
he accelerator physics and light source research program at Duke Free-Electron Laser Laboratory (DFELL), TUNL, is focused on the development of the storage ring based free-electron lasers (FELs), and a state-of-the-art Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS). Driven by the storage ring FEL, the HIGS is world's most intense Compton gamma-ray source with a maximum total flux of few 10¹⁰ gamma per second (around 10 MeV). Operated in the energy range from 1 to 100 MeV, the HIGS is a premier nuclear physics research facility in the world. In 2012, we completed a major accelerator upgrade project with a wiggler switchyard system which allows the configuration changes between planar and helical FEL wigglers, and a great enhancement of the FEL gain when operated with 3 or 4 helical wigglers. In this paper, we will describe our ongoing light source development to produce gamma-ray beams in the new energy range of 100 and 158 MeV. We will also provide a summary of our accelerator physics research activities in the area of nonlinear dynamics, beam instability research, and FEL research.

MOPEA078

Commissioning and Operation of Wiggler Switchyard System for Duke FEL and HIGS

FEL, vacuum, storage-ring, lattice

267

Y.K. Wu, M.D. Busch, M. Emamian, J.F. Faircloth, H. Hao, J.Y. Li, S.F. Mikhailov, V. Popov, G. Swift, P.W. Wallace, P. Wang, J. Yan
FEL/Duke University, Durham, North Carolina, USA
A.L. Wu
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
To enable the Duke storage ring FEL to operate in VUV with adequate gain, a major storage ring upgrade was carried out in 2012 to install two additional helical FEL wigglers with a wiggler switchyard system. Using the switchyard, a quick changeover can be made between two planar OK-4 wigglers and two helical OK-5 wigglers in the middle of the FEL straight section. This system preserves the linear polarization capabilities of the Duke FEL and gamma-ray beams at the High Intensity Gamma-ray Source (HIGS), while enabling VUV FEL operation with a higher gain using a longer FEL with as many as four helical wigglers. The wiggler switchyard upgrade was completed in Summer 2012, followed by a rapid and successful commissioning of the Duke storage ring, FEL system, and HIGS. In this paper, we will present the results of accelerator and light source commissioning with the wiggler switchyard. We will also present preliminary results of operating the OK-5 FEL in different configurations. With the wiggler switchyard, we are well positioned to realize the operation of a VUV FEL below 190 nm and production of Compton gamma-ray beams above 100 MeV in circular polarization.

TUODB102

Intrabeam Scattering Studies for Low Emittance of BAPS

emittance, damping, storage-ring, lattice

1123

S.K. Tian, Y. Jiao, J.Q. Wang, G. Xu
IHEP, Beijing, People's Republic of China

In modern storage ring light sources, intra-beam scattering (IBS) is often thought of as a fundamental limitation to achieving ultra-low emittance and hence higher brightness. Beijing Advanced Photon Source (BAPS) is under design at Institute of High Energy Physics (IHEP) which aims to emittance less than 1nm at 5GeV. To improve the coherence and high brightness, low emittance- in both transverse planes at the diffraction limit for the range of x-ray wavelengths(≈10 pm)- is being pursued. Thus, due to the very low emittance, intra-beam scattering effect is an issue. Accurate estimation to check if the design goal can be reached is necessary. In this paper, we use the 6-D accelerator simulation code-elegant and Accelerator Toolbox (AT)-a collection of tools to model storage rings in the MATLAB environment. Based on a temporary design lattice of BAPS, we present the results of particle simulation study of intra-beam scattering effect versus the beam energy, the emittance coupling factor, the bunch length, the bunch current and so on. We also studied the mitigating method by adopting damping wigglers in one or more dispersion-free regions.

Slides TUODB102 [2.338 MB]

TUPEA074

Protection of VUV FEL Mirrors using Soft Orbit Bump at Duke FEL/HIGS facility

FEL, radiation, electron, dipole

1301

S.F. Mikhailov, H. Hao, J.Y. Li, V. Popov, P.W. Wallace, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DoE grant # DE-FG02-97ER41033
The Duke FEL and High Intensity Gamma-ray Source (HIGS) facility is operated with an electron beam from 0.24 to 1.2 GeV and a photon beam from 190 to 1060 nm. Presently, the energy range of the gamma-beam is from 1 MeV to about 100 MeV, with the maximum total gamma-flux of more then 10¹⁰ gammas per second around 10 MeV. Production of high intensity, high energy gamma-beams of 60 to 100 MeV, using UV-VUV mirrors of 240 to 190 nm, requires high energy, high current electron beams of 0.9 to 1.05 GeV. Synchrotron radiation damage to the FEL mirrors becomes crucial for VUV FEL operation at or below 190 nm. The edge radiation (ER) from the End-of-Arc (EOA) bending magnet, instead of the radiation of FEL wigglers, is the dominant cause of a rapid degradation of the downstream FEL mirror. In this work, we describe a further development of the “soft” orbit bump concept to significantly reduce the radiation exposure to the mirror from the EOA dipole magnet. The bump uses designated "soft" orbit correctors with magnetic field limited to produce a radiation with a critical wavelength close or below the FEL wavelength.

TUPME005

Preparations for Beam Tests of a CLIC Damping Wiggler Prototype at ANKA

damping, emittance, target, storage-ring

1568

A. Bernhard, E. Huttel, P. Peiffer
KIT, Karlsruhe, Germany
A.V. Bragin, N.A. Mezentsev, V.M. Syrovatin, K. Zolotarev
BINP SB RAS, Novosibirsk, Russia
P. Ferracin, D. Schoerling
CERN, Geneva, Switzerland

The Compact Linear Collider (CLIC) will require ultra-low emittance electron and positron beams. The targeted emittance will be achieved by radiative damping in the CLIC damping rings. For an efficient damping high-field short-period superconducting damping wigglers will be employed. In the conceptual design phase of CLIC, the basic layout of these wigglers has been elaborated at CERN. In the course of the CLIC technical feasibility studies a full-scale damping wiggler prototype will be installed and tested in the ANKA storage ring. The device is currently under design and construction at the Budker Institute of Nuclear Physics, Russia. Above the magnetic requirements, the main design challenges for the prototype are scalability –- particularly of the cooling concept –-, modularity and the capability of sustaining a high radiative heat load. The experiments at ANKA aim at a validation of the technical concepts applied to meet these requirements. Beyond that an extended experimental program on beam dynamics and alternative technical solutions is envisaged. This contribution gives an overview over the current status of the project and the further planning.

TUPME022

Study on the Single Bunch Transverse Emittance Growth in BAPS

emittance, wakefield, lattice, vacuum

1619

J. Gao, D. Wang
IHEP, Beijing, People's Republic of China

Funding: Supported by the National Foundation of Natural Sciences Contract 11175192.
Beijing Advanced photon Source (BAPS) is a proposed next synchrotron radiation facility which has much smaller transverse emittance after SSRF in China, with 5 GeV energy and 1.5 km circumference. In order to explore how small the transverse emittance we can get on BAPS, this paper studies the single bunch transverse emittance growth due to short range wakefield according to J. Gao’ theory. The mechanism of wakefield induced single bunch emittance is explained first and then the transverse emittance at the design beam current is estimated. Also, the tolerances for the transverse loss factor and the vacuum chamber misalignment (or the closed orbit distortion) are presented.

TUPME040

TLEP: High-performance Circular e⁺e⁻ Collider to Study the Higgs Boson

polarization, luminosity, cryogenics, collider

1658

M. Koratzinos, O. Brunner, A.C. Butterworth, J.R. Ellis, P. Janot, E. Jensen, J.A. Osborne, F. Zimmermann
CERN, Geneva, Switzerland
R. Aleksan
CEA/DSM/IRFU, France
A.P. Blondel
DPNC, Genève, Switzerland
M. Zanetti
MIT, Cambridge, Massachusetts, USA

The recent discovery of a light Higgs boson has opened up considerable interest in circular e⁺e⁻ Higgs factories around the world. We report on the progress of the “TLEP3” concept since last year. Two options are considered: LEP3, a 240 GeV centre-of-mass (Ecm) e⁺e⁻ machine in the LHC tunnel with cost only a fraction of the cost of an equivalent linear collider, due to the use of existing infrastructure and the two general-purpose LHC detectors, and TLEP, an e⁺e⁻ machine in a new 80 km tunnel that can operate up to an Ecm of 350 GeV. Both concepts enjoy the extensive know-how on circular colliders and how to deliver their design luminosity, and the existence of up to four interaction points. The attainable luminosities are 10³⁴/cm²/s and 5x10³⁴/cm²/s per interaction point for LEP3 and TLEP respectively. Both machines can operate as Tera-Z and Mega-W boson factories, giving decisive opportunities for over-constraining the electroweak sector of the Standard Model. The technical challenges and possible ways to improve the performance further will be discussed.

TUPME042

The SPS as an Ultra-low Emittance Damping Ring Test Facility for CLIC

damping, emittance, optics, target

1661

Y. Papaphilippou, R. Corsini, L.R. Evans
CERN, Geneva, Switzerland

In view of the plans for a future electron/positron linear collider based on the CLIC technology, an ultra-low emittance damping ring test facility is proposed, using the CERN SPS. Optics modification, required wiggler length and characteristics, energy and RF parameters are presented in order to reach CLIC performance requirements, including the effect of Intrabeam Scattering. Considerations about the necessary injected beam characteristics, its production and transfer through the existing CERN accelerator complex are also discussed.

TUPME066

CESR Low Emittance Upgrade with Combined Function Bends

quadrupole, emittance, damping, focusing

1718

D. L. Rubin, Y. Li, A.A. Mikhailichenko, S. Wang
CLASSE, Ithaca, New York, USA

Funding: Work supported by the National Science Foundation and Department of Energy under contract numbers PHY-1002467, DMR-0936384 and DE-SC0006505
The Cornell Electron Storage Ring is the laboratory for the CESR Test Accelerator damping ring R&D program, and the source of x-rays for CHESS. A peculiarity of the layout of the storage ring is that horizontal emittance is generated predominantly by the strong bends in the sextant of the ring that was designed with a long straight to accommodate the interaction region required for operation as an electron-positron collider. By reconfiguring that single sextant we reduce the emittance by 60% to 20 nm-rad at 5.3 GeV for x-ray production and with damping wigglers to 1.3 nm-rad at 2.1 GeV for investigations of low emittance phenomena. The 35 meter radius of curvature, 3.2 meter long dipoles are refitted as combined function (vertically focusing) magnets to create simple achromats. The layout can accommodate six, 3 meter long undulators, in addition to the six existing superconducting damping wigglers. With reduced horizontal emittance and energy spread, the reconfiguration enhances the sensitivity of CESR to the emittance diluting effects that are the subject of the CesrTA study. Capability of the x-ray source is significantly improved with six new undulator beam lines.

TUPWA052

Loss Factor and Impedance Analysis for the Diamond Storage Ring

impedance, storage-ring, vacuum, simulation

1826

R. Bartolini, R.T. Fielder, C.A. Thomas
Diamond, Oxfordshire, United Kingdom

Diamond Light Source is investigating the possibility of increasing the storage ring operating current above the nominal 300 mA. A campaign of measurements and simulations has been carried out in order to understand the extent of the parasitic energy loss and characterise the most important items which build up the machine impedance. In this paper we report on the most recent measurements of the longitudinal loss factor and the present status of the impedance database with an initial comparison between the two.

TUPWA071

Studies of Resistive Wall Heating at JLAB FEL

impedance, FEL, resonance, electron

1868

R. Li, S.V. Benson
JLAB, Newport News, Virginia, USA

Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
When the JLAB FEL is under CW operation, it had been observed that temperature rises over the wiggler vacuum chamber, presumably as the result of the power deposition on the resistive wall of the wiggler chamber. Previous analyses have been done on the resistive wall impedance for various cases, such as DC, AC, and anomalous skin effects*. Here we report an investigation on the beam kinetic energy losses for each of these cases. This study includes the non-ultrarelativistic effect on resistive wall loss, for both round pipe and parallel plates. We will present the comparison of our results with the measured data obtained during CW operation of the JLAB FEL. Other possible factors contributing to the measured heating will also be discussed.
* K. Bane and G. Stupakov, SLAC-PUB-10707, 2004.

TUPWO063

Reducing HLS-II Emittance by Radiation Damping Partition Factor Exchange

emittance, storage-ring, damping, lattice

2009

J.Y. Li
FEL/Duke University, Durham, North Carolina, USA
W. Li, G. Liu, W. Xu
USTC/NSRL, Hefei, Anhui, People's Republic of China
Y. Li
BNL, Upton, Long Island, New York, USA

Funding: The Introduction of Outstanding Technological Talents Program of Chinese Academy of Sciences, 2010.
In this paper, we present a preliminary study on using a Robinson wiggler, a wiggler with transverse gradient, to reduce the horizontal beam emittance of the Hefei Light Source II (HLS-II) storage ring. A proof-of-principle study demonstrates that it is possible to further reduce the horizontal beam emittance by 50\% using a 2-meter long Robinson wiggler installed on a dispersive straight section. This encouraging result suggests a feasible option to significantly improve the HLS-II performance at a relative low cost and without significant modification to its global configuration in the near future.

WEPWA001

Wigglers at Danfysik

electron, damping, radiation, emittance

2123

C.W.O. Ostenfeld, M. Pedersen
Danfysik A/S, Taastrup, Denmark

In the past 2 years, a number of insertion devices have been designed, assembled and tested at Danfysik. They are used for a variety of applications at free electron lasers and synchrotron radiation facilities. In this paper, we highlight 3 different wiggler projects: A 2.0 T wiggler for Astrid-II in Århus, Denmark, a fixed-gap electromagnetic wiggler for Helmholtz Center Dresden-Rossendorf, and 6 identical damping wigglers for NSLS-2 at Brookhaven National Laboratory (BNL). For the Astrid-2 facility in Aarhus, Denmark, we have designed and built a 6 period wiggler, with a peak field of 2.0 T. The magnetic design and performance is presented and discussed. As part of the ELBE THz facility, at Helmholtz Center Dresden-Rossendorf, we have designed and built a fixed-gap electromagnetic wiggler, with 300 mm period length, and a peak field of 0.39 T. We present the design and magnetic results. For the NSLS-2 project at BNL, damping wigglers are an integral part of the design, both as a means of reducing the emittance, but also as a source of intense radiation sources for users. We present the mechanical and magnetic design, as well as magnetic results obtained for the wigglers.

WEPME038

Slow Orbit Feedback and Beam Stability at ALBA

photon, injection, electron, feedback

3010

J. Marcos, M. Muñoz
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

ALBA is a 3GeV 3rd generation synchrotron radiation source built nearby Barcelona providing service to users since May 2012. During all this period, a Slow Orbit Feedback system (SOFB) has been running during users’ operation in order to deliver a stable photon beam to the Beamlines. The system employs 88 out of the 10⁴ Beam Position Monitors (BPMs) available at ALBA and 88 horizontal and vertical correctors. In addition, since the middle of the year (July 2012), the reading of the X-Ray BPM (XBPM) for one of the Front Ends, with a Bending Magnet as a source, has also been included in the correction loop. In this paper we summarize the performance of the SOFB system. Besides, we also present data corresponding to the evolution along the year of the XBPM readings for several Front Ends that have a planar Insertion Device (ID) as a source. The analyzed XBPMs are not included in the orbit correction loop, and consequently they supply information regarding the long term stability of ALBA Storage Ring.

THPEA057

Compensation Schemes for Operation of FEL Wigglers on Duke Storage Ring

FEL, storage-ring, lattice, quadrupole

3270

J.Y. Li, H. Hao, S.F. Mikhailov, V. Popov, W. Wu, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
The Duke FEL is the photon driver for the High Intensity Gamma-ray Source (HIGS). To extend the capabilities of the FEL and HIGS to higher photon energy regions, a FEL wiggler switchyard system was developed in the recent years. This system was installed and commissioned in 2012. The FEL wiggler switchyard is used to change between two planar OK-4 wigglers and two helical OK-5 wigglers in the middle of the FEL straight section in a short period of time (a few days). With a total of six electromagnetic wigglers, the Duke FEL can be operated in a number of wiggler configurations and with a wide range of magnetic fields. The operation of uncompensated FEL wigglers can cause significant changes to the electron beam closed orbit and magnetic lattice. To maintain a sufficiently large dynamic aperture for an efficient injection and good beam lifetime, a set of complex compensation schemes, including magnetic field and lattice compensation, have been developed for the operation of the FEL wigglers. This paper reports the overall architecture and performance of the FEL wiggler compensation schemes and their implementation in the accelerator controls system using the feedforward mechanism.