IPAC2012 - List of Keywords (wiggler)

Paper	Title	Other Keywords	Page
MOPPD016	Status of Proof-of-principle Experiment for Coherent Electron Cooling	electron, gun, ion, FEL	400
	I. Pinayev, S.A. Belomestnykh, I. Ben-Zvi, J. Bengtsson, A. Elizarov, A.V. Fedotov, D.M. Gassner, Y. Hao, D. Kayran, V. Litvinenko, G.J. Mahler, W. Meng, T. Roser, B. Sheehy, R. Than, J.E. Tuozzolo, G. Wang, S.D. Webb, V. Yakimenko BNL, Upton, Long Island, New York, USA G.I. Bell, D.L. Bruhwiler, V.H. Ranjbar, B.T. Schwartz Tech-X, Boulder, Colorado, USA A. Hutton, G.A. Krafft, M. Poelker, R.A. Rimmer JLAB, Newport News, Virginia, USA M.A. Kholopov, P. Vobly BINP SB RAS, Novosibirsk, Russia
	Funding: US DOE Office of Science, DE-FC02-07ER41499, DE-FG02-08ER85182; NERSC DOE contract No. DE-AC02-05CH11231. Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. To verify the concept we conduct proof-of-the-principle experiment at RHIC. In this paper, we describe the current experimental setup to be installed into 2 o’clock RHIC interaction regions. We present current design, status of equipment acquisition and estimates for the expected beam parameters.

MOPPP061	Using RADIA to Model Superconducting Wigglers at the Canadian Light Source	sextupole, insertion, insertion-device, vacuum	699
	C.K. Baribeau, L.O. Dallin, M.J. Sigrist, W.A. Wurtz CLS, Saskatoon, Saskatchewan, Canada
	The Canadian Light Source operates two superconducting wigglers: a 2 Tesla, 63 pole wiggler, and a 4 Tesla, 27 pole wiggler. Both SCWs have a negative impact on the injection efficiency. Beam based measurements indicate a larger than expected sextupole moment, and the 4T wiggler produces a large horizontal tune shift. To better understand these effects, computer models were developed for the SCWs using the magnetic modelling software package, RADIA. The RADIA models accurately predict the wiggler on-axis field strength and vertical tune shift. By introducing physical misalignments, the models can produce sextupole moments of the same order of magnitude as the measured quantities. However, the modelled horizontal tune shift is orders of magnitude smaller than the 4T wiggler’s observed tune shift. Various model parameters were investigated for their effect on horizontal tune shift, but the cause of the 4T wiggler’s large horizontal tune shift remains unknown.

MOPPP062	Soleil Emittance Reduction using a Robinson Wiggler	photon, emittance, brightness, damping	702
	H.B. Abualrob, P. Brunelle, M.-E. Couprie, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	For both synchrotron light sources as SOLEIL and colliders, the emittance is one of the key parameters to increase the photon brightness and the beam luminosity. In order to decrease the emittance, the ring optics is built on very focusing lattices leading to large chromaticities and potential reduction of the dynamics aperture and momentum transverse acceptance. Thus, some facilities have installed damping wigglers in zero dispersion straight sections to relax the optics and to reach sub-nanometer horizontal emittances. This solution requires however tens or hundreds meters of insertion devices. For storage ring equipped with zero-gradient bending magnets, an alternative solution can be given by installing a single Robinson wiggler [1] in a dispersive section enabling to divide the emittance by a factor 2. The uniqueness of this wiggler results from the presence of an alternated gradient superimposed the main periodic magnetic field. This paper recalls the concept of the wiggler, presents the expected gain for SOLEIL storage ring with the impact on the linear optics and the brightness. A preliminary magnetic design is also proposed. [1] K.W. Robinson, Phys. Rev, p. 373 (1958).

MOPPP079	Magnetic Tuning of the APS Wiggler as a Study for Tuning the NSLS-II Damping Wiggler	multipole, damping, octupole, insertion	747
	I. Vasserman, M. Abliz, E. Gluskin, E. Trakhtenberg, J.Z. Xu ANL, Argonne, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 A wide variety of tuning techniques has been developed and employed at Advanced Photon Source (APS) in the course of tuning insertion devices for use on the APS storage ring, the APS free electron laser, and in assisting with the LCLS undulator tuning. The tuning requirements for the National Synchrotron Source II (NSLS-II) damping wigglers are very demanding and include limits on the off-midplane field integrals that are new in the repertoire of undulator magnetic tuning. The goal of this study was to assess the applicability of existing tuning techniques to meeting the off-midplane requirements of NSLS-II. Tests were run using an available APS 8.5-cm-period wiggler. In addition to existing techniques, a special new shim design was tested. This report summarizes the results of these tests and shows that the wiggler can be tuned to the required specifications on the midplane over the requested ±15 mm in the horizontal direction. In the vertical direction, however, the specifications could only be met within ±0.5 mm. This falls short of the ±15 mm by ± 3 mm good-field region that is sought by NSLS-II.

TUXB01	Progress Towards Ultimate Storage Ring Light Sources	emittance, brightness, electron, dipole	1035
	M. Borland ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Developments such as the low emittance NSLS-II storage ring, followed by the even lower emittance MAX-IV ring, demonstrate that the technology of storage ring light sources has not reached full maturity. Indeed, these new sources are paving the way toward realizing diffraction-limited angstrom-wavelength storage ring light sources in the not-too-distant future. Our discussion begins with a review of recent trends and developments in storage ring design. We then survey on-going work around the world to develop concepts and designs for so-called "ultimate" storage ring light sources.
	Slides TUXB01 [3.442 MB]

TUOAA01	3-Dimensional Modeling of Electron Clouds in Non-uniform Magnetic Fields	plasma, electron, simulation, resonance	1059
	S.A. Veitzer, P. Stoltz Tech-X, Boulder, Colorado, USA J.A. Crittenden, K.G. Sonnad CLASSE, Ithaca, New York, USA
	Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499) and by the National Science Foundation Grant PHY-0734867. Electron clouds have the potential to pose serious limitations on accelerator performance in both hadron and lepton beams. Experiments using rf diagnostics are being performed to measure electron cloud densities at a number of accelerator facilities. However, it is difficult to calibrate plasma density with signal strength in these experiments, and modeling involves a number of technical and numerical challenges. Typically 2-Dimensional electrostatic methods have been used to model cloud buildup under beam crossing conditions. However, since traveling-wave rf experiments typically occur over many meters of beam pipe where magnetic fields are changing, one needs to develop 3-Dimensional electromagnetic models in order to accurately simulate rf diagnostics. We have developed accurate models of electron cloud-induced phase shifts in rf in a system with spatially varying magnetic field configurations using the plasma simulation code VORPAL. We present here results for measuring phase shifts in the CESR wiggler with realistic, spatially non-uniform magnetic field configurations.
	Slides TUOAA01 [18.367 MB]

TUOBC03	Experimental Measurements of e-Cloud Mitigation using Clearing Electrodes in the DAΦNE Collider	positron, vacuum, dipole, electron	1107
	D. Alesini, T. Demma, A. Drago, A. Gallo, S. Guiducci, C. Milardi, P. Raimondi, M. Zobov INFN/LNF, Frascati (Roma), Italy S. De Santis LBNL, Berkeley, California, USA
	Recently the electron-positron collider DAΦNE has started delivering luminosity to the KLOE-2 experiment. For this run special metallic electrodes for e-cloud clearing were installed in all the dipole and wiggler magnets of the collider positron ring. Experimental measurements of the effectiveness of the electrodes in the mitigation of the e-cloud effects in the positron beam have been done showing an impressive effectiveness of these devices in the cure of the e-cloud effects in the positron beam. In particular the electrodes allow reducing the vertical beam size increase, the growth rate of transverse instabilities and the tune shifts induced by the electron cloud. Frequency shifts measurements of the vacuum chamber resonances switching on and off the electrodes have also been done showing their effect in the reduction of the electron cloud density. In this paper we summarize the results of all our observations and the experimental measurements of the e-cloud suppression with these electrodes.
	Slides TUOBC03 [2.825 MB]

TUPPC047	New Storage Ring Lattice for the Duke FEL Wiggler Switchyard System	lattice, FEL, storage-ring, quadrupole	1272
	H. Hao, J.Y. Li, 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 storage ring is a dedicated drive for the OK-4 FEL and OK-5 FEL, and for the state-of-the-art Compton gamma-ray source, High Intensity Gamma-Ray Source (HIGS). To produce FEL lasing below 190 nm and gamma-ray beams above 100 MeV, the FEL system needs to be upgraded by adding two helical OK-5 wigglers to increase the FEL gain with four OK5 wigglers for the VUV operation. To simultaneously preserve the linear polarization capability of the gamma-ray beam produced by the planar OK-4 FEL, a wiggler switchyard system is under development which will enable the switch between two planar OK-4 wigglers and two helical OK-5 wigglers in the middle of the FEL straight. In this work, we present the new magnetic lattice designed for the operation of the wiggler switchyard system. This new lattice is developed with great flexibility for the operation with different numbers of FEL wigglers, variable betatron tunes, and adjustable electron beam sizes at the collision point for the HIGS. In addition, the new lattice is developed for the operation in a wide range of energies, from 280 MeV to 1.2 GeV, with proper nonlinear dynamics compensations in order to realize a large dynamic aperture.

TUPPC086	Conceptual Design of the CLIC damping rings	emittance, damping, positron, vacuum	1368
	Y. Papaphilippou, F. Antoniou, M.J. Barnes, S. Calatroni, P. Chiggiato, R. Corsini, A. Grudiev, J. Holma, T. Lefèvre, M. Martini, M. Modena, N. Mounet, A. Perin, Y. Renier, G. Rumolo, S. Russenschuck, H. Schmickler, D. Schoerling, D. Schulte, M. Taborelli, G. Vandoni, F. Zimmermann CERN, Geneva, Switzerland C. Belver-Aguilar, A. Faus-Golfe IFIC, Valencia, Spain A. Bernhard KIT, Karlsruhe, Germany M.J. Boland ASCo, Clayton, Victoria, Australia A.V. Bragin, E.B. Levichev, S.V. Sinyatkin, P. Vobly, K. Zolotarev BINP SB RAS, Novosibirsk, Russia M. Korostelev Cockcroft Institute, Warrington, Cheshire, United Kingdom E. Koukovini EPFL, Lausanne, Switzerland M.A. Palmer CLASSE, Ithaca, New York, USA M.T.F. Pivi, S.R. Smith SLAC, Menlo Park, California, USA R.P. Rassool, K.P. Wootton The University of Melbourne, Melbourne, Australia L. Rinolfi JUAS, Archamps, France A. Vivoli Fermilab, Batavia, USA
	The CLIC damping rings are designed to produce unprecedentedly low-emittances of 500 nm and 5 nm normalized at 2.86 GeV, in all beam dimensions with high bunch charge, necessary for the performance of the collider. The large beam brightness triggers a number of beam dynamics and technical challenges. Ring parameters such as energy, circumference, lattice, momentum compaction, bending and super-conducting wiggler fields are carefully chosen in order to provide the target emittances under the influence of intrabeam scattering but also reduce the impact of collective effects such as space-charge and coherent synchrotron radiation. Mitigation techniques for two stream instabilities have been identified and tested. The low vertical emittance is achieved by modern orbit and coupling correction techniques. Design considerations and plans for technical system, such as damping wigglers, transfer systems, vacuum, RF cavities, instrumentation and feedback are finally reviewed.

TUPPP001	Beam Based Measurements with Superconducting Wigglers at the Canadian Light Source with Applications to Nonlinear Beam Dynamics	injection, dynamic-aperture, optics, multipole	1599
	W.A. Wurtz, L.O. Dallin, M.J. Sigrist CLS, Saskatoon, Saskatchewan, Canada
	The Canadian Light Source (CLS) employs two superconducting wigglers for the production of hard x-rays. These wigglers cause a large decrease in injection efficiency. While such a decrease is not unexpected due to the large distortion to the linear optics, a correction to the linear optics does not restore injection efficiency. This inability to restore injection is not predicted by a kickmap model of the wiggler. We performed beam based measurements to construct a phenomenological, nonlinear model of the wiggler. Particle tracking with this wiggler model shows that the reduction in dynamic aperture is due to the amplitude dependent tune shift crossing a resonance, even with the linear optics corrected. Moving the tunes allows us to avoid this resonance and measurements at these tunes show that injection efficiency is not greatly affected by the wigglers.

TUPPP021	Orbit Stability at ALBA	insertion, insertion-device, booster, undulator	1653
	M. Muñoz, G. Benedetti, D. Einfeld, J. Marcos, Z. Martí CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	The synchrotron light source ALBA is in the final stage of the Storage Ring commissioning, with the beamline commissioning well under way. In the month of beam line commissioning, the storage ring has provided an stable beam, with horizontal and vertical stabilities better than the micrometer in both planes in DC and a good reproducibility of the beam position day by day. In this paper we review the performance of the Slow Orbit Feedback, the changes in orbit due to insertion devices, as well as the first measurement using the 10 kHz sampling mode of the Libera BPMs, together with the status of the implementation of the Fast Orbit Feedback system.

TUPPP027	Subpicosecond Laser Slicing X-Ray Source for Time-resolved Research at TPS	laser, emittance, photon, lattice	1671
	W.K. Lau, M.C. Chou, C.-S. Hwang, A.P. Lee, Y.-C. Liu, G.-H. Luo NSRRC, Hsinchu, Taiwan N.Y. Huang NTHU, Hsinchu, Taiwan
	The 3 GeV Taiwan Photon Source (TPS) under construction at NSRRC should be ready for user run in 2014. X-ray users in many research areas will then be benefited. However, there has been a growing interest in ultrafast time-resolved research in the island. The feasibility of using ultrafast laser for electron-beam slicing at TPS to produce sub-picosecond x-ray pulses is being investigated recently. The design and layout of a laser slicing scheme with W250 wiggler as the energy modulator in a 7 m medium straight section and EPU48 and IU22 radiators in other straight sections will be presented. It will offer the unique opportunity to gain experience in experimental techniques needed for FEL science.

TUPPP076	Soft Orbit Bumps for Duke Storage Ring VUV FEL Operation	FEL, radiation, electron, dipole	1774
	S.F. Mikhailov, 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. The current range of the gamma-beam energy 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 the high intensity, high energy gamma-beams of 60-100 MeV using UV-VUV mirrors of 240 - 190 nm requires and high energy, high current electron beams of 0.9-1.05 GeV. The radiation damage problem becomes more severe for VUV FEL operation below 190 nm. The radiation from the End-of-Arc (EOA) bending magnets, instead of the radiation from FEL wigglers, is the dominant cause of a rapid degradation of the downstream FEL mirror. In this work, we propose a number of measures to significantly reduce the radiation from these dipole magnets as well as other potential sources of synchrotron radiation toward the FEL mirror. In particular, we describe the development of an orbit bump using designated "soft" orbit correctors. The magnetic field of these correctors is limited to produce a radiation with a critical wavelength close or below the FEL wavelength.

TUPPP086	A Synchronized FIR/VUV Light Source at Jefferson Lab	FEL, laser, electron, coupling	1789
	S.V. Benson, D. Douglas, G. Neil, M.D. Shinn, G.P. Williams JLAB, Newport News, Virginia, USA
	Funding: This work was supported by U.S. DOE Contract No. DE-AC05-84-ER40150, the Air Force Office of Scientific Research, DOE Basic Energy Sciences. We describe a dual FEL configuration on the UV Demo FEL at Jefferson Lab that would allow simultaneous lasing at THz and UV wavelengths. The THz source would be an FEL oscillator with a short wiggler providing diffraction-limited pulses with pulse energy exceeding 50 microJoules. The THz source would use the exhaust beam from a UVFEL. The coherent harmonics in the VUV from the UVFEL are outcoupled through a hole. The THz source uses a shorter resonator with either hole or edge coupling to provide very high power THz pulses. Simulations indicate excellent spectral brightness in the THz region with over 100 W/cm^-1 output.

TUPPP087	Commissioning of the Fritz Haber Institute Mid-IR FEL	FEL, electron, linac, undulator	1792
	A.M.M. Todd, H. Bluem, D. Dowell, R. Lange, J.H. Park, J. Rathke, L.M. Young AES, Princeton, New Jersey, USA W. Erlebach, S. Gewinner, H. Junkes, A. Liedke, G. Meijer, W. Schöllkopf, W.Q. Zhang, G. von Helden FHI, Berlin, Germany S.C. Gottschalk STI, Washington, USA K. Jordan Kevin Jordan PE, Newport News, Virginia, USA U. Lehnert, P. Michel, W. Seidel HZDR, Dresden, Germany R. Wünsch FZD, Dresden, Germany
	The IR and THz FEL at the Fritz Haber Institute (FHI) in Berlin is designed to deliver radiation from 4 to 400 microns. A single-plane-focusing undulator combined with a 5.4-m-long cavity is used is the mid-IR (< 50 micron), while a two-plane-focusing undulator in combination with a 7.2-m-long cavity with a 1-D waveguide for the optical mode is planned for the far-IR. Beam was delivered to the IR beam dump in November 2011. We describe progress since that time in completing the commissioning of the mid-IR beamline and the status of the far-IR beamline design and fabrication.

TUPPP092	Renovated Two-stage Bunch Compressor for the International Linear Collider	positron, linac, linear-collider, collider	1801
	S. Seletskiy BNL, Upton, Long Island, New York, USA N. Solyak Fermilab, Batavia, USA
	The International Linear Collider (ILC) utilizes a Bunch Compressor (BC) in the Damping Ring to Main Linac Transfer Line (RTML) that compresses the RMS bunch length from 6 mm to 300 micrometers before sending the beam to the Main Linac. It was decided to utilize a two stage BC for the design baseline, since it provides an additional option for the ILC to work with 150 micrometers long bunches and reduces the energy spread at the RTML exit under normal operational conditions. In this paper we report the new design of the optimized two-stage bunch compressor.

TUPPP093	General Results on the Nature of FEL Amplification	electron, FEL, laser, free-electron-laser	1804
	S.D. Webb Tech-X, Boulder, Colorado, USA V. Litvinenko, G. Wang BNL, Upton, Long Island, New York, USA
	Free-electron lasers are increasingly important tools for the material and biological sciences, and although numerical and analytical theory is extensive, a fundamental question about the nature of the FEL growing modes has remained unanswered. In this proceeding, we present results of a topological nature concerning the number of amplifying solutions to the 1-dimensional FEL equations as related to the energy distribution of the electron bunches.

TUPPR006	Design Progress and Construction Status of SuperKEKB	quadrupole, dipole, status, klystron	1822
	H. Koiso, K. Akai, K. Oide KEK, Ibaraki, Japan
	KEKB operation finished in June 2010, and the upgrade of KEKB to SuperKEKB has commenced. The design luminosity of SuperKEKB is 8×10³⁵cm^-2s^-1, which is 40 times higher than that of KEKB. The design strategy for SuperKEKB is based on the Nano-Beam Scheme, where the vertical beam sizes of the low-energy positron ring and the high-energy electron ring are squeezed to 50−60 nm at the interaction point with a large Piwinski angle. The beam currents in both rings will be double those in KEKB. Finalizing the design of the interaction region is going on by using precise modeling of beam optics. Dismantling KEKB rings and fabrication of accelerator components for SuperKEKB including magnets, power supplies, and antechamber-type beam pipes have already started. This paper describes design progress and construction status of SuperKEKB.

TUPPR061	First Magnetic Test of a Superconducting Nb3Sn Wiggler Magnet for CLIC	damping, emittance, plasma, electron	1957
	D. Schoerling, P. Ferracin, P. Fessia, M. Karppinen, J. Mazet, S. Russenschuck CERN, Geneva, Switzerland A.W. Grau Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany P. Peiffer KIT, Karlsruhe, Germany
	In the Compact Linear Collider (CLIC) the normalized horizontal and vertical emittances of the electron and positron beams must be reduced to 500 nm and 5 nm before the beams enter the 3 TeV linear accelerators. An effective way to accomplish ultra-low emittances are damping rings. Damping rings are storage rings equipped with strong wiggler magnets. In a first approximation damping wigglers are more effective the shorter the period length and the stronger the magnetic field is. Only superconducting wiggler magnets meet the demanding magnetic specifications of the CLIC damping rings. Nb-Ti damping wiggler magnets fulfill the specifications of CLIC but Nb3Sn wiggler magnets would reach higher magnetic fields leading to even better beam properties for CLIC. Moreover, they have at the same time higher thermal and magnetic margins. Therefore, Nb3Sn wiggler magnets are under investigation at CERN despite the challenging manufacturing process. This paper presents first results of Nb3Sn coils and short model tests and outlines the further plans for developing Nb3Sn wiggler magnets at CERN.

TUPPR062	The Conceptual Design of a Vacuum System for the ILC Damping Rings Incorporating Electron Cloud Mitigation Techniques	vacuum, electron, photon, damping	1960
	J.V. Conway, Y. Li, M.A. Palmer CLASSE, Ithaca, New York, USA
	Funding: Work Supported by DOE Award DE-SC0006505. We describe the conceptual design of the vacuum system for the damping rings of the International Linear Collider. The design incorporates a range of techniques to suppress the development of the electron cloud (EC) in the positron ring. These techniques include coatings with low secondary electron yield (SEY), grooved chambers, clearing electrodes and antechambers for photoelectron control. The EC mitigation choices are based on the ILC Electron Cloud R&D program, which has been conducted at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) and at other collaborating institutions. The conceptual designs for vacuum chambers in drifts, dipoles, wigglers and quadrupoles are presented. The International Linear Collider: A Technical Progress Report, E. Elsen et al., Eds., pp. 71-81 (2011).

TUPPR063	Investigation into Electron Cloud Effects in the ILC Damping Ring Design	photon, vacuum, electron, lattice	1963
	J.A. Crittenden, J.V. Conway, G. Dugan, M.A. Palmer, D. L. Rubin CLASSE, Ithaca, New York, USA L.E. Boon, K.C. Harkay ANL, Argonne, USA M.A. Furman LBNL, Berkeley, California, USA S. Guiducci INFN/LNF, Frascati (Roma), Italy M.T.F. Pivi, L. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy DE-SC0006506 We report modeling results for electron cloud buildup in the ILC damping ring lattice design. Updated optics, wiggler magnet, and vacuum chamber designs have recently been developed for the 5-GeV, 3.2-km racetrack layout. An analysis of the synchrotron radiation profile around the ring has been performed, including the effect of photon scattering on the interior of the vacuum chamber. Operational implications of the resulting electron cloud buildup will be discussed.

TUPPR065	Wiggler Magnet Design Development for the ILC Damping Rings	damping, vacuum, lattice, linear-collider	1969
	J.A. Crittenden, M.A. Palmer, D. L. Rubin CLASSE, Ithaca, New York, USA
	Funding: Work supported by the U.S. Department of Energy DE-SC0006506. The baseline damping ring lattice design for the International Linear Collider employs nearly 60 2.2-m-long superconducting wiggler magnets to provide the damping necessary to achieve the specified horizontal emittance. We describe the OPERA-based finite-element model developed for the 14-pole, 30-cm period, 7.62-cm gap superferric design which meets the 2.1 T peak field requirement. Transfer functions and field uniformity results are discussed. We present results for the accuracy of the optimized analytic model needed for symplectic tracking algorithms, as well as implications for the updated engineering design.

TUPPR066	Characterization of Single Particle Dynamics for the International Linear Collider Damping Ring Lattice	damping, emittance, lattice, multipole	1972
	J.P. Shanks, J.A. Crittenden, M.A. Palmer CLASSE, Ithaca, New York, USA D.L. Rubin Cornell University, Ithaca, New York, USA
	Funding: DOE Award DE-SC0006506 The baseline design for the International Linear Collider damping rings is a 3.2 km circumference racetrack, with 5 GeV beam energy. The transverse damping time is 26 ms and the normalized horizontal emittance 5 mm-mrad. Nearly 60 2.2-m-long superconducting wigglers per ring increase the radiation damping rate by an order of magnitude and reduce horizontal emittance by a factor of 5. We characterize the sensitivity to magnet misalignments and field errors, and establish the minimum numbers of corrector magnets and beam position monitors required for tuning vertical emittance to less than 20 nm-rad. We validate the specified tolerable guide field multipole errors consistent with adequate dynamic aperture. Tune scans are used to identify stable working points. In tracking studies we use a wiggler model based on fits to 3-dimensional field maps.

WEYB03	High Average Power UV Free Electron Laser Experiments at JLAB	FEL, cavity, linac, electron	2111
	D. Douglas, S.V. Benson, P. Evtushenko, J.G. Gubeli, C. Hernandez-Garcia, R.A. Legg, G. Neil, T. Powers, M.D. Shinn, C. Tennant, G.P. Williams JLAB, Newport News, Virginia, USA
	Funding: Authored by JSA LLC under US DOE Contract #DE-AC05-06OR23177. The U.S. Gov. retains non-exclusive, paid-up, irrevocable, world-wide license to publish/reproduce this manuscript for U.S. Gov. purposes. Having produced 14 kW of average power at ~2 microns, JLAB has shifted its focus to the ultraviolet portion of the spectrum. This presentation will describe the JLab UV Demo FEL, present specifics of its driver ERL, and discuss the latest experimental results from FEL experiments and machine operations.
	Slides WEYB03 [2.863 MB]

WEPPR054	Calculation of Coherent Wiggler Radiation using Eigenfunction Expansion Method	impedance, radiation, damping, space-charge	3048
	D. Zhou, Y.H. Chin, K. Ohmi KEK, Ibaraki, Japan G.V. Stupakov SLAC, Menlo Park, California, USA
	An analytic method originated by Y. H. Chin* was extended to calculate the electromagnetic fields and the longitudinal impedance due to coherent wiggler radiation (CWR) in a rectangular chamber. The method used dyadic Green functions based on eigenfunction expansion method in electromagnetic theory and was rigorous for the case of straight chamber. We re-derived the theory and did find the full expressions for the longitudinal impedance of a wiggler with finite length. With shielding of chamber, the CWR impedance indicated resonant properties which were not seen in the theory for CWR in free space. * Y.H. Chin, LBL-29981, 1990.

Paper

Title

Other Keywords

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MOPPD016

Status of Proof-of-principle Experiment for Coherent Electron Cooling

electron, gun, ion, FEL

400

I. Pinayev, S.A. Belomestnykh, I. Ben-Zvi, J. Bengtsson, A. Elizarov, A.V. Fedotov, D.M. Gassner, Y. Hao, D. Kayran, V. Litvinenko, G.J. Mahler, W. Meng, T. Roser, B. Sheehy, R. Than, J.E. Tuozzolo, G. Wang, S.D. Webb, V. Yakimenko
BNL, Upton, Long Island, New York, USA
G.I. Bell, D.L. Bruhwiler, V.H. Ranjbar, B.T. Schwartz
Tech-X, Boulder, Colorado, USA
A. Hutton, G.A. Krafft, M. Poelker, R.A. Rimmer
JLAB, Newport News, Virginia, USA
M.A. Kholopov, P. Vobly
BINP SB RAS, Novosibirsk, Russia

Funding: US DOE Office of Science, DE-FC02-07ER41499, DE-FG02-08ER85182; NERSC DOE contract No. DE-AC02-05CH11231.
Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. To verify the concept we conduct proof-of-the-principle experiment at RHIC. In this paper, we describe the current experimental setup to be installed into 2 o’clock RHIC interaction regions. We present current design, status of equipment acquisition and estimates for the expected beam parameters.

MOPPP061

Using RADIA to Model Superconducting Wigglers at the Canadian Light Source

sextupole, insertion, insertion-device, vacuum

699

C.K. Baribeau, L.O. Dallin, M.J. Sigrist, W.A. Wurtz
CLS, Saskatoon, Saskatchewan, Canada

The Canadian Light Source operates two superconducting wigglers: a 2 Tesla, 63 pole wiggler, and a 4 Tesla, 27 pole wiggler. Both SCWs have a negative impact on the injection efficiency. Beam based measurements indicate a larger than expected sextupole moment, and the 4T wiggler produces a large horizontal tune shift. To better understand these effects, computer models were developed for the SCWs using the magnetic modelling software package, RADIA. The RADIA models accurately predict the wiggler on-axis field strength and vertical tune shift. By introducing physical misalignments, the models can produce sextupole moments of the same order of magnitude as the measured quantities. However, the modelled horizontal tune shift is orders of magnitude smaller than the 4T wiggler’s observed tune shift. Various model parameters were investigated for their effect on horizontal tune shift, but the cause of the 4T wiggler’s large horizontal tune shift remains unknown.

MOPPP062

Soleil Emittance Reduction using a Robinson Wiggler

photon, emittance, brightness, damping

702

H.B. Abualrob, P. Brunelle, M.-E. Couprie, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

For both synchrotron light sources as SOLEIL and colliders, the emittance is one of the key parameters to increase the photon brightness and the beam luminosity. In order to decrease the emittance, the ring optics is built on very focusing lattices leading to large chromaticities and potential reduction of the dynamics aperture and momentum transverse acceptance. Thus, some facilities have installed damping wigglers in zero dispersion straight sections to relax the optics and to reach sub-nanometer horizontal emittances. This solution requires however tens or hundreds meters of insertion devices. For storage ring equipped with zero-gradient bending magnets, an alternative solution can be given by installing a single Robinson wiggler [1] in a dispersive section enabling to divide the emittance by a factor 2. The uniqueness of this wiggler results from the presence of an alternated gradient superimposed the main periodic magnetic field. This paper recalls the concept of the wiggler, presents the expected gain for SOLEIL storage ring with the impact on the linear optics and the brightness. A preliminary magnetic design is also proposed. [1] K.W. Robinson, Phys. Rev, p. 373 (1958).

MOPPP079

Magnetic Tuning of the APS Wiggler as a Study for Tuning the NSLS-II Damping Wiggler

multipole, damping, octupole, insertion

747

I. Vasserman, M. Abliz, E. Gluskin, E. Trakhtenberg, J.Z. Xu
ANL, Argonne, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
A wide variety of tuning techniques has been developed and employed at Advanced Photon Source (APS) in the course of tuning insertion devices for use on the APS storage ring, the APS free electron laser, and in assisting with the LCLS undulator tuning. The tuning requirements for the National Synchrotron Source II (NSLS-II) damping wigglers are very demanding and include limits on the off-midplane field integrals that are new in the repertoire of undulator magnetic tuning. The goal of this study was to assess the applicability of existing tuning techniques to meeting the off-midplane requirements of NSLS-II. Tests were run using an available APS 8.5-cm-period wiggler. In addition to existing techniques, a special new shim design was tested. This report summarizes the results of these tests and shows that the wiggler can be tuned to the required specifications on the midplane over the requested ±15 mm in the horizontal direction. In the vertical direction, however, the specifications could only be met within ±0.5 mm. This falls short of the ±15 mm by ± 3 mm good-field region that is sought by NSLS-II.

TUXB01

Progress Towards Ultimate Storage Ring Light Sources

emittance, brightness, electron, dipole

1035

M. Borland
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Developments such as the low emittance NSLS-II storage ring, followed by the even lower emittance MAX-IV ring, demonstrate that the technology of storage ring light sources has not reached full maturity. Indeed, these new sources are paving the way toward realizing diffraction-limited angstrom-wavelength storage ring light sources in the not-too-distant future. Our discussion begins with a review of recent trends and developments in storage ring design. We then survey on-going work around the world to develop concepts and designs for so-called "ultimate" storage ring light sources.

Slides TUXB01 [3.442 MB]

TUOAA01

3-Dimensional Modeling of Electron Clouds in Non-uniform Magnetic Fields

plasma, electron, simulation, resonance

1059

S.A. Veitzer, P. Stoltz
Tech-X, Boulder, Colorado, USA
J.A. Crittenden, K.G. Sonnad
CLASSE, Ithaca, New York, USA

Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499) and by the National Science Foundation Grant PHY-0734867.
Electron clouds have the potential to pose serious limitations on accelerator performance in both hadron and lepton beams. Experiments using rf diagnostics are being performed to measure electron cloud densities at a number of accelerator facilities. However, it is difficult to calibrate plasma density with signal strength in these experiments, and modeling involves a number of technical and numerical challenges. Typically 2-Dimensional electrostatic methods have been used to model cloud buildup under beam crossing conditions. However, since traveling-wave rf experiments typically occur over many meters of beam pipe where magnetic fields are changing, one needs to develop 3-Dimensional electromagnetic models in order to accurately simulate rf diagnostics. We have developed accurate models of electron cloud-induced phase shifts in rf in a system with spatially varying magnetic field configurations using the plasma simulation code VORPAL. We present here results for measuring phase shifts in the CESR wiggler with realistic, spatially non-uniform magnetic field configurations.

Slides TUOAA01 [18.367 MB]

TUOBC03

Experimental Measurements of e-Cloud Mitigation using Clearing Electrodes in the DAΦNE Collider

positron, vacuum, dipole, electron

1107

D. Alesini, T. Demma, A. Drago, A. Gallo, S. Guiducci, C. Milardi, P. Raimondi, M. Zobov
INFN/LNF, Frascati (Roma), Italy
S. De Santis
LBNL, Berkeley, California, USA

Recently the electron-positron collider DAΦNE has started delivering luminosity to the KLOE-2 experiment. For this run special metallic electrodes for e-cloud clearing were installed in all the dipole and wiggler magnets of the collider positron ring. Experimental measurements of the effectiveness of the electrodes in the mitigation of the e-cloud effects in the positron beam have been done showing an impressive effectiveness of these devices in the cure of the e-cloud effects in the positron beam. In particular the electrodes allow reducing the vertical beam size increase, the growth rate of transverse instabilities and the tune shifts induced by the electron cloud. Frequency shifts measurements of the vacuum chamber resonances switching on and off the electrodes have also been done showing their effect in the reduction of the electron cloud density. In this paper we summarize the results of all our observations and the experimental measurements of the e-cloud suppression with these electrodes.

Slides TUOBC03 [2.825 MB]

TUPPC047

New Storage Ring Lattice for the Duke FEL Wiggler Switchyard System

lattice, FEL, storage-ring, quadrupole

1272

H. Hao, J.Y. Li, 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 storage ring is a dedicated drive for the OK-4 FEL and OK-5 FEL, and for the state-of-the-art Compton gamma-ray source, High Intensity Gamma-Ray Source (HIGS). To produce FEL lasing below 190 nm and gamma-ray beams above 100 MeV, the FEL system needs to be upgraded by adding two helical OK-5 wigglers to increase the FEL gain with four OK5 wigglers for the VUV operation. To simultaneously preserve the linear polarization capability of the gamma-ray beam produced by the planar OK-4 FEL, a wiggler switchyard system is under development which will enable the switch between two planar OK-4 wigglers and two helical OK-5 wigglers in the middle of the FEL straight. In this work, we present the new magnetic lattice designed for the operation of the wiggler switchyard system. This new lattice is developed with great flexibility for the operation with different numbers of FEL wigglers, variable betatron tunes, and adjustable electron beam sizes at the collision point for the HIGS. In addition, the new lattice is developed for the operation in a wide range of energies, from 280 MeV to 1.2 GeV, with proper nonlinear dynamics compensations in order to realize a large dynamic aperture.

TUPPC086

Conceptual Design of the CLIC damping rings

emittance, damping, positron, vacuum

1368

Y. Papaphilippou, F. Antoniou, M.J. Barnes, S. Calatroni, P. Chiggiato, R. Corsini, A. Grudiev, J. Holma, T. Lefèvre, M. Martini, M. Modena, N. Mounet, A. Perin, Y. Renier, G. Rumolo, S. Russenschuck, H. Schmickler, D. Schoerling, D. Schulte, M. Taborelli, G. Vandoni, F. Zimmermann
CERN, Geneva, Switzerland
C. Belver-Aguilar, A. Faus-Golfe
IFIC, Valencia, Spain
A. Bernhard
KIT, Karlsruhe, Germany
M.J. Boland
ASCo, Clayton, Victoria, Australia
A.V. Bragin, E.B. Levichev, S.V. Sinyatkin, P. Vobly, K. Zolotarev
BINP SB RAS, Novosibirsk, Russia
M. Korostelev
Cockcroft Institute, Warrington, Cheshire, United Kingdom
E. Koukovini
EPFL, Lausanne, Switzerland
M.A. Palmer
CLASSE, Ithaca, New York, USA
M.T.F. Pivi, S.R. Smith
SLAC, Menlo Park, California, USA
R.P. Rassool, K.P. Wootton
The University of Melbourne, Melbourne, Australia
L. Rinolfi
JUAS, Archamps, France
A. Vivoli
Fermilab, Batavia, USA

The CLIC damping rings are designed to produce unprecedentedly low-emittances of 500 nm and 5 nm normalized at 2.86 GeV, in all beam dimensions with high bunch charge, necessary for the performance of the collider. The large beam brightness triggers a number of beam dynamics and technical challenges. Ring parameters such as energy, circumference, lattice, momentum compaction, bending and super-conducting wiggler fields are carefully chosen in order to provide the target emittances under the influence of intrabeam scattering but also reduce the impact of collective effects such as space-charge and coherent synchrotron radiation. Mitigation techniques for two stream instabilities have been identified and tested. The low vertical emittance is achieved by modern orbit and coupling correction techniques. Design considerations and plans for technical system, such as damping wigglers, transfer systems, vacuum, RF cavities, instrumentation and feedback are finally reviewed.

TUPPP001

Beam Based Measurements with Superconducting Wigglers at the Canadian Light Source with Applications to Nonlinear Beam Dynamics

injection, dynamic-aperture, optics, multipole

1599

W.A. Wurtz, L.O. Dallin, M.J. Sigrist
CLS, Saskatoon, Saskatchewan, Canada

The Canadian Light Source (CLS) employs two superconducting wigglers for the production of hard x-rays. These wigglers cause a large decrease in injection efficiency. While such a decrease is not unexpected due to the large distortion to the linear optics, a correction to the linear optics does not restore injection efficiency. This inability to restore injection is not predicted by a kickmap model of the wiggler. We performed beam based measurements to construct a phenomenological, nonlinear model of the wiggler. Particle tracking with this wiggler model shows that the reduction in dynamic aperture is due to the amplitude dependent tune shift crossing a resonance, even with the linear optics corrected. Moving the tunes allows us to avoid this resonance and measurements at these tunes show that injection efficiency is not greatly affected by the wigglers.

TUPPP021

Orbit Stability at ALBA

insertion, insertion-device, booster, undulator

1653

M. Muñoz, G. Benedetti, D. Einfeld, J. Marcos, Z. Martí
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

The synchrotron light source ALBA is in the final stage of the Storage Ring commissioning, with the beamline commissioning well under way. In the month of beam line commissioning, the storage ring has provided an stable beam, with horizontal and vertical stabilities better than the micrometer in both planes in DC and a good reproducibility of the beam position day by day. In this paper we review the performance of the Slow Orbit Feedback, the changes in orbit due to insertion devices, as well as the first measurement using the 10 kHz sampling mode of the Libera BPMs, together with the status of the implementation of the Fast Orbit Feedback system.

TUPPP027

Subpicosecond Laser Slicing X-Ray Source for Time-resolved Research at TPS

laser, emittance, photon, lattice

1671

W.K. Lau, M.C. Chou, C.-S. Hwang, A.P. Lee, Y.-C. Liu, G.-H. Luo
NSRRC, Hsinchu, Taiwan
N.Y. Huang
NTHU, Hsinchu, Taiwan

The 3 GeV Taiwan Photon Source (TPS) under construction at NSRRC should be ready for user run in 2014. X-ray users in many research areas will then be benefited. However, there has been a growing interest in ultrafast time-resolved research in the island. The feasibility of using ultrafast laser for electron-beam slicing at TPS to produce sub-picosecond x-ray pulses is being investigated recently. The design and layout of a laser slicing scheme with W250 wiggler as the energy modulator in a 7 m medium straight section and EPU48 and IU22 radiators in other straight sections will be presented. It will offer the unique opportunity to gain experience in experimental techniques needed for FEL science.

TUPPP076

Soft Orbit Bumps for Duke Storage Ring VUV FEL Operation

FEL, radiation, electron, dipole

1774

S.F. Mikhailov, 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. The current range of the gamma-beam energy 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 the high intensity, high energy gamma-beams of 60-100 MeV using UV-VUV mirrors of 240 - 190 nm requires and high energy, high current electron beams of 0.9-1.05 GeV. The radiation damage problem becomes more severe for VUV FEL operation below 190 nm. The radiation from the End-of-Arc (EOA) bending magnets, instead of the radiation from FEL wigglers, is the dominant cause of a rapid degradation of the downstream FEL mirror. In this work, we propose a number of measures to significantly reduce the radiation from these dipole magnets as well as other potential sources of synchrotron radiation toward the FEL mirror. In particular, we describe the development of an orbit bump using designated "soft" orbit correctors. The magnetic field of these correctors is limited to produce a radiation with a critical wavelength close or below the FEL wavelength.

TUPPP086

A Synchronized FIR/VUV Light Source at Jefferson Lab

FEL, laser, electron, coupling

1789

S.V. Benson, D. Douglas, G. Neil, M.D. Shinn, G.P. Williams
JLAB, Newport News, Virginia, USA

Funding: This work was supported by U.S. DOE Contract No. DE-AC05-84-ER40150, the Air Force Office of Scientific Research, DOE Basic Energy Sciences.
We describe a dual FEL configuration on the UV Demo FEL at Jefferson Lab that would allow simultaneous lasing at THz and UV wavelengths. The THz source would be an FEL oscillator with a short wiggler providing diffraction-limited pulses with pulse energy exceeding 50 microJoules. The THz source would use the exhaust beam from a UVFEL. The coherent harmonics in the VUV from the UVFEL are outcoupled through a hole. The THz source uses a shorter resonator with either hole or edge coupling to provide very high power THz pulses. Simulations indicate excellent spectral brightness in the THz region with over 100 W/cm^-1 output.

TUPPP087

Commissioning of the Fritz Haber Institute Mid-IR FEL

FEL, electron, linac, undulator

1792

A.M.M. Todd, H. Bluem, D. Dowell, R. Lange, J.H. Park, J. Rathke, L.M. Young
AES, Princeton, New Jersey, USA
W. Erlebach, S. Gewinner, H. Junkes, A. Liedke, G. Meijer, W. Schöllkopf, W.Q. Zhang, G. von Helden
FHI, Berlin, Germany
S.C. Gottschalk
STI, Washington, USA
K. Jordan
Kevin Jordan PE, Newport News, Virginia, USA
U. Lehnert, P. Michel, W. Seidel
HZDR, Dresden, Germany
R. Wünsch
FZD, Dresden, Germany

The IR and THz FEL at the Fritz Haber Institute (FHI) in Berlin is designed to deliver radiation from 4 to 400 microns. A single-plane-focusing undulator combined with a 5.4-m-long cavity is used is the mid-IR (< 50 micron), while a two-plane-focusing undulator in combination with a 7.2-m-long cavity with a 1-D waveguide for the optical mode is planned for the far-IR. Beam was delivered to the IR beam dump in November 2011. We describe progress since that time in completing the commissioning of the mid-IR beamline and the status of the far-IR beamline design and fabrication.

TUPPP092

Renovated Two-stage Bunch Compressor for the International Linear Collider

positron, linac, linear-collider, collider

1801

S. Seletskiy
BNL, Upton, Long Island, New York, USA
N. Solyak
Fermilab, Batavia, USA

The International Linear Collider (ILC) utilizes a Bunch Compressor (BC) in the Damping Ring to Main Linac Transfer Line (RTML) that compresses the RMS bunch length from 6 mm to 300 micrometers before sending the beam to the Main Linac. It was decided to utilize a two stage BC for the design baseline, since it provides an additional option for the ILC to work with 150 micrometers long bunches and reduces the energy spread at the RTML exit under normal operational conditions. In this paper we report the new design of the optimized two-stage bunch compressor.

TUPPP093

General Results on the Nature of FEL Amplification

electron, FEL, laser, free-electron-laser

1804

S.D. Webb
Tech-X, Boulder, Colorado, USA
V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA

Free-electron lasers are increasingly important tools for the material and biological sciences, and although numerical and analytical theory is extensive, a fundamental question about the nature of the FEL growing modes has remained unanswered. In this proceeding, we present results of a topological nature concerning the number of amplifying solutions to the 1-dimensional FEL equations as related to the energy distribution of the electron bunches.

TUPPR006

Design Progress and Construction Status of SuperKEKB

quadrupole, dipole, status, klystron

1822

H. Koiso, K. Akai, K. Oide
KEK, Ibaraki, Japan

KEKB operation finished in June 2010, and the upgrade of KEKB to SuperKEKB has commenced. The design luminosity of SuperKEKB is 8×10³⁵cm^-2s^-1, which is 40 times higher than that of KEKB. The design strategy for SuperKEKB is based on the Nano-Beam Scheme, where the vertical beam sizes of the low-energy positron ring and the high-energy electron ring are squeezed to 50−60 nm at the interaction point with a large Piwinski angle. The beam currents in both rings will be double those in KEKB. Finalizing the design of the interaction region is going on by using precise modeling of beam optics. Dismantling KEKB rings and fabrication of accelerator components for SuperKEKB including magnets, power supplies, and antechamber-type beam pipes have already started. This paper describes design progress and construction status of SuperKEKB.

TUPPR061

First Magnetic Test of a Superconducting Nb3Sn Wiggler Magnet for CLIC

damping, emittance, plasma, electron

1957

D. Schoerling, P. Ferracin, P. Fessia, M. Karppinen, J. Mazet, S. Russenschuck
CERN, Geneva, Switzerland
A.W. Grau
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
P. Peiffer
KIT, Karlsruhe, Germany

In the Compact Linear Collider (CLIC) the normalized horizontal and vertical emittances of the electron and positron beams must be reduced to 500 nm and 5 nm before the beams enter the 3 TeV linear accelerators. An effective way to accomplish ultra-low emittances are damping rings. Damping rings are storage rings equipped with strong wiggler magnets. In a first approximation damping wigglers are more effective the shorter the period length and the stronger the magnetic field is. Only superconducting wiggler magnets meet the demanding magnetic specifications of the CLIC damping rings. Nb-Ti damping wiggler magnets fulfill the specifications of CLIC but Nb3Sn wiggler magnets would reach higher magnetic fields leading to even better beam properties for CLIC. Moreover, they have at the same time higher thermal and magnetic margins. Therefore, Nb3Sn wiggler magnets are under investigation at CERN despite the challenging manufacturing process. This paper presents first results of Nb3Sn coils and short model tests and outlines the further plans for developing Nb3Sn wiggler magnets at CERN.

TUPPR062

The Conceptual Design of a Vacuum System for the ILC Damping Rings Incorporating Electron Cloud Mitigation Techniques

vacuum, electron, photon, damping

1960

J.V. Conway, Y. Li, M.A. Palmer
CLASSE, Ithaca, New York, USA

Funding: Work Supported by DOE Award DE-SC0006505.
We describe the conceptual design of the vacuum system for the damping rings of the International Linear Collider. The design incorporates a range of techniques to suppress the development of the electron cloud (EC) in the positron ring. These techniques include coatings with low secondary electron yield (SEY), grooved chambers, clearing electrodes and antechambers for photoelectron control. The EC mitigation choices are based on the ILC Electron Cloud R&D program, which has been conducted at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) and at other collaborating institutions*. The conceptual designs for vacuum chambers in drifts, dipoles, wigglers and quadrupoles are presented.
* The International Linear Collider: A Technical Progress Report, E. Elsen et al., Eds., pp. 71-81 (2011).

TUPPR063

Investigation into Electron Cloud Effects in the ILC Damping Ring Design

photon, vacuum, electron, lattice

1963

J.A. Crittenden, J.V. Conway, G. Dugan, M.A. Palmer, D. L. Rubin
CLASSE, Ithaca, New York, USA
L.E. Boon, K.C. Harkay
ANL, Argonne, USA
M.A. Furman
LBNL, Berkeley, California, USA
S. Guiducci
INFN/LNF, Frascati (Roma), Italy
M.T.F. Pivi, L. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy DE-SC0006506
We report modeling results for electron cloud buildup in the ILC damping ring lattice design. Updated optics, wiggler magnet, and vacuum chamber designs have recently been developed for the 5-GeV, 3.2-km racetrack layout. An analysis of the synchrotron radiation profile around the ring has been performed, including the effect of photon scattering on the interior of the vacuum chamber. Operational implications of the resulting electron cloud buildup will be discussed.

TUPPR065

Wiggler Magnet Design Development for the ILC Damping Rings

damping, vacuum, lattice, linear-collider

1969

J.A. Crittenden, M.A. Palmer, D. L. Rubin
CLASSE, Ithaca, New York, USA

Funding: Work supported by the U.S. Department of Energy DE-SC0006506.
The baseline damping ring lattice design for the International Linear Collider employs nearly 60 2.2-m-long superconducting wiggler magnets to provide the damping necessary to achieve the specified horizontal emittance. We describe the OPERA-based finite-element model developed for the 14-pole, 30-cm period, 7.62-cm gap superferric design which meets the 2.1 T peak field requirement. Transfer functions and field uniformity results are discussed. We present results for the accuracy of the optimized analytic model needed for symplectic tracking algorithms, as well as implications for the updated engineering design.

TUPPR066

Characterization of Single Particle Dynamics for the International Linear Collider Damping Ring Lattice

damping, emittance, lattice, multipole

1972

J.P. Shanks, J.A. Crittenden, M.A. Palmer
CLASSE, Ithaca, New York, USA
D.L. Rubin
Cornell University, Ithaca, New York, USA

Funding: DOE Award DE-SC0006506
The baseline design for the International Linear Collider damping rings is a 3.2 km circumference racetrack, with 5 GeV beam energy. The transverse damping time is 26 ms and the normalized horizontal emittance 5 mm-mrad. Nearly 60 2.2-m-long superconducting wigglers per ring increase the radiation damping rate by an order of magnitude and reduce horizontal emittance by a factor of 5. We characterize the sensitivity to magnet misalignments and field errors, and establish the minimum numbers of corrector magnets and beam position monitors required for tuning vertical emittance to less than 20 nm-rad. We validate the specified tolerable guide field multipole errors consistent with adequate dynamic aperture. Tune scans are used to identify stable working points. In tracking studies we use a wiggler model based on fits to 3-dimensional field maps.

WEYB03

High Average Power UV Free Electron Laser Experiments at JLAB

FEL, cavity, linac, electron

2111

D. Douglas, S.V. Benson, P. Evtushenko, J.G. Gubeli, C. Hernandez-Garcia, R.A. Legg, G. Neil, T. Powers, M.D. Shinn, C. Tennant, G.P. Williams
JLAB, Newport News, Virginia, USA

Funding: Authored by JSA LLC under US DOE Contract #DE-AC05-06OR23177. The U.S. Gov. retains non-exclusive, paid-up, irrevocable, world-wide license to publish/reproduce this manuscript for U.S. Gov. purposes.
Having produced 14 kW of average power at ~2 microns, JLAB has shifted its focus to the ultraviolet portion of the spectrum. This presentation will describe the JLab UV Demo FEL, present specifics of its driver ERL, and discuss the latest experimental results from FEL experiments and machine operations.

Slides WEYB03 [2.863 MB]

WEPPR054

Calculation of Coherent Wiggler Radiation using Eigenfunction Expansion Method

impedance, radiation, damping, space-charge

3048

D. Zhou, Y.H. Chin, K. Ohmi
KEK, Ibaraki, Japan
G.V. Stupakov
SLAC, Menlo Park, California, USA

An analytic method originated by Y. H. Chin* was extended to calculate the electromagnetic fields and the longitudinal impedance due to coherent wiggler radiation (CWR) in a rectangular chamber. The method used dyadic Green functions based on eigenfunction expansion method in electromagnetic theory and was rigorous for the case of straight chamber. We re-derived the theory and did find the full expressions for the longitudinal impedance of a wiggler with finite length. With shielding of chamber, the CWR impedance indicated resonant properties which were not seen in the theory for CWR in free space.
* Y.H. Chin, LBL-29981, 1990.