PAC07 - List of Keywords (wiggler)

A B C D E F G H I K L M O P Q R S T U V W

wiggler

Paper	Title	Other Keywords	Page
MOOAKI01	Plans for Utilizing the Cornell Electron Storage Ring as a Test Accelerator for ILC Damping Ring Research and Development	emittance, damping, electron, instrumentation	42
	M. A. Palmer J. P. Alexander, D. L. Hartill, R. W. Helms, D. L. Rubin, J. P. Shanks, M. Tigner, J. T. Urban CLASSE, Ithaca M. Ehrlichman University of Minnesota, Minneapolis, Minnesota D. H. Rice CESR-LEPP, Ithaca, New York D. Sagan Cornell University, Department of Physics, Ithaca, New York L. Schachter Technion, Haifa
	Funding: Funding provided by NSF grant PHY-0202078 In April 2008, we propose to begin operation of the Cornell Electron Storage Ring (CESR) as a test accelerator, CesrTA, for International Linear Collider (ILC) damping ring research. Utilizing 12 damping wigglers, the baseline CesrTA lattice at 2.0 GeV will offer a natural geometric emittance of 2.25 nm. An experimental program has been laid out which focuses on several key areas of damping rings R&D. First we will test vacuum chamber designs to suppress electron cloud growth in the wiggler magnets. Secondly, we will develop correction, tuning and emittance monitoring strategies to achieve vertical emittances of a few picometers. As part of this effort we will validate alignment and survey techniques being developed by the Linear Collider Alignment and Survey group (LiCAS) for curved tunnel applications. After achieving ultra-low emittance, we intend to explore the impact of the electron cloud, the fast ion instability and other beam dynamics effects on ultra-low emittance beams. Finally, we plan to test various technical systems required for the ILC damping rings. This paper provides an update on conceptual design issues for CesrTA and describes the experimental program in detail.
	Slides

MOZBKI01	CESR-C: A Wiggler-Dominated Collider	optics, damping, luminosity, electron	48
	D. H. Rice
	Funding: Work supported by US National Science Foundation grant PHY-0202078 CESR-c operates with twelve 2.1 Tesla wigglers that account for 90% of the synchrotron radiation with beam energy in the range of 1.8 to 2.1 GeV. The wigglers reduce the radiation damping time from 0.5 seconds to 50 milliseconds. The carefully designed wigglers restrict neither physical nor dynamic aperture of the storage ring, though both quadrupole and sextupole distributions must be tailored to compensate the primary optics effects of the wigglers. Colliding beam performance limits are determined by the numerous parasitic beam-beam interactions in the single ring. Several approaches taken to mitigate these limiting effects are described herein. The CESR-c wigglers are an excellent match to the requirements for future damping rings. We describe how with flexible optics, extensive infrastructure, and resource expertise, they form an effective test bed for assessment and solution of damping ring issues such as electron cloud and ion effects, and achieving ultra-low emittance beams.
	Slides

MOZAAB01	Generation of Subpicosecond X-ray Pulses in Storage Rings	electron, laser, radiation, synchrotron	69
	A. Zholents
	Funding: This work was supported by DoE under contract No: DE-AC02-05CH11231 Subpicosecond x-ray pulses are now routinely obtained at the ALS, BESSY and SLS light sources using laser e-beam slicing technique. Other x-ray pulse shortening techniques were also proposed and are now under consideration for ALS, APS, DIAMOND and PETRA light sources. In this talk I review current results and discuss R&D plans and activity.
	Slides

MOOAAB01	Philosophy for NSLS II Design with Sub-nanometer Horizontal Emittance	emittance, lattice, dipole, storage-ring	77
	S. Ozaki J. Bengtsson, S. L. Kramer, S. Krinsky, V. Litvinenko BNL, Upton, Long Island, New York
	In this paper we present design philosophy for reliable light sources with sub-nm horizontal emittance used for conceptual design of NSLS II. We discuss the fundamentals of the concept, such as using reliable achromatic low-emittance lattice with large bending radius and damping wigglers with modest peak field. We also discuss a natural scale of the emittance set by intra-beam scattering and its influence of the choice of the bending radius for the ring. In addition, we review a very weak dependence of the beam lifetime on the emittance, and present a clear physics explanation of the phenomena. Finally, we list main parameters of the 3 GeV NSLS II X-ray ring.
	Slides

MOOAAB03	High Power Operation of the JLab IR FEL Driver Accelerator	laser, electron, vacuum, beam-losses	83
	S. V. Benson K. Beard, G. H. Biallas, J. Boyce, D. B. Bullard, J. L. Coleman, D. Douglas, H. F.D. Dylla, R. Evans, P. Evtushenko, C. W. Gould, A. C. Grippo, J. G. Gubeli, D. Hardy, C. Hernandez-Garcia, C. Hovater, K. Jordan, J. M. Klopf, R. Li, S. W. Moore, G. Neil, M. Poelker, T. Powers, J. P. Preble, R. A. Rimmer, D. W. Sexton, M. D. Shinn, C. Tennant, R. L. Walker, G. P. Williams, S. Zhang Jefferson Lab, Newport News, Virginia
	Funding: This work supported by the Off. of Naval Research, the Joint Technology Off., the Commonwealth of Virginia, the Air Force Research Lab, Army Night Vision Lab, and by DOE Contract DE-AC05-060R23177. Operation of the JLab IR Upgrade FEL at CW powers in excess of 10 kW requires sustained production of high electron beam powers by the driver ERL. This in turn demands attention to numerous issues and effects, including: cathode lifetime; control of beamline and RF system vacuum during high current operation; longitudinal space charge; longitudinal and transverse matching of irregular/large volume phase space distributions; halo management; management of remnant dispersive effects; resistive wall, wake-field, and RF heating of beam vacuum chambers; the beam break up instability; the impact of coherent synchrotron radiation (both on beam quality and the performance of laser optics); magnetic component stability and reproducibility; and RF stability and reproducibility. We discuss our experience with these issues and describe the modus vivendi that has evolved during prolonged high current, high power beam and laser operation.
	Slides

MOPAN022	Investigation of Machine Operation and Related Radiation Dose at the ANKA Storage Ring	undulator, radiation, storage-ring, injection	197
	I. Birkel E. Huttel, A.-S. Muller, P. Wesolowski FZK, Karlsruhe
	A new online network for radiation dose measurements offers the opportunity to register the dose rate at the ANKA storage ring every minute. The network consists of six mobile and two stationary monitors with a gamma and a neutron detector and a central computer. The analysis of the dose rate shows strong correlations between beam energy, current, machine parameters and dose rate.

MOPAN023	Superconductive Damping Wigglers for the CLIC Project	damping, emittance, radiation, undulator	200
	R. Rossmanith T. Baumbach, A. Bernhard, A.-S. Muller, D. Wollmann University of Karlsruhe, Karlsruhe H.-H. Braun, M. Korostelev, Y. Papaphilippou, F. Zimmermann CERN, Geneva S. Casalbuoni, A. W. Grau, M. Hagelstein, B. K. Kostka FZK, Karlsruhe E. Mashkina, E. Steffens University of Erlangen-Nurnberg, Physikalisches Institut II, Erlangen
	The CLIC damping ring requires wigglers with both high on-axis fields and short periods. The present design foresees a superconductive wiggler with a period length of 5 cm, a peak on-axis field of 2.5 T and a full width aperture of 12 mm. In this paper we explore the performance improvements of the damping ring when these parameters are pushed to 2.7 T at a period length of 2 cm with the expense of a reduced aperture of 5 mm. A design for a prototype for testing the field quality of such a wiggler is presented in this paper and the possibility to test this wiggler with beam in the storage ring ANKA is described.

MOPAN091	Design of Mechanical Structure and Cryostat for IASW Superconducting Wiggler at NSRRC	vacuum, cryogenics, superconductivity, shielding	374
	H.-H. Chen C.-H. Chang, T.-C. Fan, M.-H. Huang, C.-S. Hwang, J. C. Jan, F.-Y. Lin NSRRC, Hsinchu
	An in-achromatic superconducting wiggler (IASW) was successfully constructed and installed at the Taiwan Light Source (TLS) in January 2006. The cryostat with a 30 L liquid nitrogen aluminum reservoir shielding surrounds the helium vessel, which comprises the cold mass and 100 L liquid helium. The helium vessel is suspended by eight suspension links, which are thermally intercepted at 80 K and can be adjusted by applying tension, such that the center of the cold mass does not move during cooled to 4.2 K. A three-layered stainless tube was designed to prevent the transfer port from freezing and the steam- electricity separation system is designed to supply electricity and return the helium gas to prevent freezing of the power feedthrough.

MOPAS025	Conceptual Design of ILC Damping Ring Wiggler Straight Vacuum System	photon, quadrupole, vacuum, damping	488
	S. Marks K. Kennedy, D. W. Plate, D. Schlueter, M. S. Zisman LBNL, Berkeley, California
	Funding: U. S. Department of Energy, Contract No. DE-AC02-05CH11231. The positron and electron damping rings for the ILC (International Linear Collider) will contain long straight sections consisting of twenty wiggler/quadrupole pairs. The wigglers will be based upon the CESR-C superconducting design* . There are a number of challenges associated with the design of the wiggler straight vacuum system, in particular, the absorption of photon power generated by the wigglers. This paper will present the overall conceptual design of the wiggler straight vacuum system developed for the ILC RDR. Particular emphasis will be placed on photon power load calculations and the absorber design. * A. Mihailichenko, Optimized Wiggler Magnet for CESR, Proceedings of PAC2001, Chicago, Il, June 18-22, 2001

TUPMN071	Planning of Insertion Devices for 3 GeV Taiwan Photon Source	undulator, photon, insertion, insertion-device	1082
	C.-S. Hwang
	The Taiwan Photon Source (TPS) has 24 straight sections (10.9 m x6,5.7 m x18). It has at least three long straight and 18 medium straight for installing insertion devices. Most of the insertion devices are the in-vacuum undulator and produce intense X-rays with a brilliance of up to 1x10²⁰ photons/s/mr²/mm²/0.1%bw. However, the cryogenic permanent magnet undulator with a periodic length of 1.8 cm (CU1.8) will be developed to provide an energy over 20 keV. One or two types of undulators can be installed in the long straight section to provide low photon energy or enable experiments to be conducted in situ in a single beam line. Meanwhile, some elliptically polarized undulators (APPLE II structure) are planned to provide circular and any linear polarization light. One or two superconducting wigglers with a field strength of 3.5 T will be used to yield the photons with energies of over 25 keV. A study project of superconducting undulator is for the energies of 2.5 - 25 keV. This work will report the design philosophy for the insertion devices and what kinds of insertion devices will be operated at TPS.

TUPMN088	Commissioning and Investigation of Beam Dynamics of Phase I Insertion Devices at Diamond	injection, optics, quadrupole, undulator	1118
	B. Singh R. Bartolini, R. T. Fielder, E. C. Longhi, I. P.S. Martin Diamond, Oxfordshire
	Diamond is a 3 GeV low emittance third generation light source recently commissioned in Oxfordshire, UK. During Phase I of the project, seven insertion devices (IDs) have been installed and commissioned: these include 5 in-vacuum permanent magnet undulators, a variable polarization APPLE-II helical device and a superconducting wiggler. We present our experiences commissioning these devices and the results of the investigations of their effects on beam dynamics, including orbit distortion, linear tune shifts, beta-beating and beam lifetime. Alpha-matching with local and global tune compensations, as well as the LOCO algorithm, have been used to compensate the linear optic perturbations. The results are discussed and compared with theoretical predictions. Injection with IDs in operation has also been investigated in view of future top-up operation.

TUPMN090	Evaluation of the Possibility of Using Damping Wigglers in the Advanced Photon Source	emittance, damping, lattice, storage-ring	1124
	M. Borland L. Emery ANL, Argonne, Illinois
	Funding: Work supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) is a 7-GeV storage ring light source that has been in operation for over a decade. Over time, the performance of the APS has been increased by reduction of the emittance from 8 nm to 3.1 nm and by the use of top-up mode. We continue to explore options for improving the performance further. This paper discusses the possible improvements in emittance that could result from the use of damping wigglers. We also discuss rf and space requirements.

TUPMN107	A Proposed Multipole Wiggler for CAMD	storage-ring, injection, lattice, radiation	1161
	V. P. Suller M. G. Fedurin BNL, Upton, Long Island, New York P. Jines, D. J. Launey, T. A. Miller, Y. Wang LSU/CAMD, Baton Rouge, Louisiana
	It is proposed to replace the 7 Tesla wavelength shifter, which has been operating in CAMD since 1998, with a superconducting Multi Pole Wiggler (MPW). This will have 11 main poles with peak fields of 7.5 Tesla and will be accommodated in a cryo-cooled cryostat whose overall length will be 2.5 m. It will be necessary to modify the storage ring lattice parameters in order to inject into the reduced 20 mm vertical aperture of this MPW. The results are presented of tests which have been made of several different lattice configurations which have low vertical beta at the proposed location of the MPW.

TUPMN108	Particle-in-Cell Calculations of the Electron Cloud in the ILC Positron Damping Ring Wigglers	electron, damping, positron, simulation	1164
	C. M. Celata M. A. Furman, J.-L. Vay LBNL, Berkeley, California D. P. Grote LLNL, Livermore, California
	Funding: This work was supported by the Office of High Energy Physics of the U. S. Department of Energy under contract number No. DE-AC02-05CH11231. Due to copious synchrotron radiation from the beam, electron cloud effects are predicted to be important in the wiggler sections of the ILC positron damping ring. In this area of the ring, the physics is inherently 3D. Moreover, a self-consistent calculation of the physics of the electron cloud/beam system is necessary for examining such phenomena as emittance growth in the beam. We present the first calculations of this system with the self-consistent 3D particle-in-cell code WARP/POSINST. The code includes self-consistent space charge for both species, mesh refinement, and detailed models of primary and secondary electron production. Interaction with electrons is assumed to occur only in the wigglers in this model– the beam is moved using maps between wiggler sections.

TUPMN119	Energy Recovery Transport Design for Peking University FEL	electron, recirculation, beam-transport, laser	1191
	G. M. Wang Y.-C. Chao Jefferson Lab, Newport News, Virginia J.-E. Chen, C. Liu, Z. C. Liu, X. Y. Lu, K. Zhao, J. Zhuang PKU/IHIP, Beijing
	Funding: supported by National 973 Projects and the U. S. Department of Energy Contract No. DE-AC05-06OR23177 A free-electron laser based on a superconducting linac is under construction in Peking University. To increase FEL output power, energy recovery is chosen as one of the most potential and popular ways. The design of a beam transport system for energy recovery is presented, which is suitable for the Peking University construction area. Especially, a chicane structure is chosen to change path length at ±20 degree and M56 in the arc is adjusted for fully bunch compression.

TUPMS017	Accelerator Physics Research and Light Source Development Programs at Duke University	booster, storage-ring, electron, synchrotron	1215
	Y. K. Wu
	Funding: This work is supported by the US AFOSR MFEL grant #FA9550-04-01-0086 and by U. S. DoE grant DE-FG05-91ER40665. The Duke Free-Electron Laser Laboratory (DFELL) has recently completed two major accelerator/light source development projects - we successfully commissioned the world's first distributed optical klystron FEL (DOK-1 FEL) and a new 0.27-1.2 GeV booster synchrotron. The DOK-1 FEL has a much improved FEL gain compared with traditional optical klystrons. This allows the DOK-1 FEL to become a versatile light source for UV-VUV operation and as a driver for a high-intensity Compton gamma-source. The top-off booster injector for the Duke storage ring is part of the upgrade project of High Intensity Gamma-ray Source (HIGS), a facility jointly developed by the DFELL and Triangle Universities Nuclear Laboratory (TUNL). The accelerator and light source development has created new opportunities for the accelerator physics research. In this paper, we will report our recent progress in accelerator and light source development as well as the ongoing accelerator physics research programs to meet the new challenges in the areas of beam dynamics and beam instability.

TUPMS024	Development of a 100 mm Period Hybrid Wiggler for the Australian Synchrotron Project	multipole, electron, synchrotron, background	1233
	J. Kulesza K. I. Blomqvist MAX-lab, Lund A. Deyhim, E. A. Johnson, D. J. Waterman Advanced Design Consulting, Inc, Lansing, New York C. Glover ASP, Clayton, Victoria
	Funding: Australian Synchrotron Project This paper summarizes the final magnetic measurement for a hybrid wiggler installed at the Australian Synchrotron Project (ASP). This device uses an anti-symmetric, hybrid design with a period of 100 mm and 40 full-strength Vanadium-Permendur poles surrounded by Neodynium-Iron-Boron magnets. It is designed to operate at two gaps with critical energies of 11.4 (14mm) and 9.6 keV (18.16mm) and to have a maximum gap with the field strength By ≤ 50 G. The wiggler's drive mechanism is capable of moving from minimum to maximum gap in 96 seconds. End terminations are designed to maintain the electron trajectory on-axis. The straightness of the electron orbit is controlled by moving the poles vertically and horizontally. The integrated multipoles are controlled over the interval \|x\| < 25 mm and all gap sizes by moving the side magnets, installing correction magnets at the wiggler entrance and exit and using correction coils. All adjustments have been made using threaded fasteners. No shims have been used.

TUPMS046	Integration of the Optical Replica Ultrashort Electron Bunch Diagnostics with the Current-Enhanced SASE in the LCLS	electron, laser, radiation, diagnostics	1293
	Y. T. Ding P. Emma, Z. Huang SLAC, Menlo Park, California
	In this paper, we present a feasibility study of integrating the optical replica (OR) ultrashort electron bunch diagnostics * with the current-enhanced SASE (ESASE) scheme ** in the LCLS. Both techniques involve using an external laser to energy-modulate the electron beam in a short wiggler and converting the energy modulation to a density modulation in a dispersive section. While ESASE proposes to use the high-current spikes to enhance the FEL signal, the OR method extracts the optical coherent radiation produced by a density modulated electron beam for frequency resolved optical gating (FROG) diagnostics. We discuss the optimization studies of combining the OR method with the ESASE after the second bunch compressor in the LCLS. Simulation results show that the OR method is capable of reproducing the expected double-horn current profile of a 200-fs bunch. The possibilities and limitations of reconstructing the longitudinal phase space profile are also explored. * E. Saldin et al, Nucl. Instr. and Meth. A 539, 499 (2005).** A. Zholents, Phys. Rev. ST Accel. Beams 8, 040701 (2005); A. Zholents et al., in Proceedings of FEL2004, 582 (2004).

TUPMS065	JLAMP: An Amplifier Based FEL in the JLab SRF ERL Driver	injection, emittance, electron, undulator	1329
	K. Jordan S. V. Benson, D. Douglas, P. Evtushenko, C. Hernandez-Garcia, G. Neil Jefferson Lab, Newport News, Virginia
	Funding: This work supported by the Off. of Naval Research, the Joint Technology Off., the Commonwealth of Virginia, the Air Force Research Lab, Army Night Vision Lab, and by DOE Contract DE-AC05-060R23177. Notional designs for ERL-driven high average power free electron lasers often invoke amplifier-based architectures. To date, however, amplifier FELs have been limited in average power output to values several orders of magnitude lower than those demonstrated in optical-resonator based systems; this is due at least in part to the limited electron beam powers available from their driver accelerators. In order to directly contrast the performance available from amplifiers to that provided by high-power cavity-based resonators, we have developed a scheme to test an amplifier FEL in the JLab SRF ERL driver. We describe an accelerator system design that can seamlessly and non-invasively integrate a 10 m wiggler into the existing system and which provides, at least in principle, performance that would support high-efficiency lasing in an amplifier configuration. Details of the design and an accelerator performance analysis will be presented.

TUPMS071	Upgrade Alternatives for the NSLS Superconducting Wiggler	photon, radiation, insertion, insertion-device	1335
	M. G. Fedurin P. Mortazavi, J. B. Murphy, G. Rakowsky BNL, Upton, Long Island, New York
	The superconducting wiggler (SCW) with 4.2 Tesla field in 5 main poles has been in operation on the NSLS X-ray storage ring for more than 20 years. The inefficient cryogenic system of this wiggler uses a closed-cycle refrigerator requiring constant maintenance. It is possible to replace this insertion device with a 13-pole SCW originally built by Oxford Instruments. The cryostat of this device could be upgraded to reduce the liquid He consumption using cryocoolers, thereby greatly reducing the refrigerator operating expense. A second option is a new design of a SCW with a magnetic period and number of poles appropriate to the current users needs. All these upgrade possibilities will be described in the paper.

TUPMS073	Dispersion Tolerance Calculation for NSLS-II	emittance, insertion, insertion-device, damping	1341
	W. Guo S. Krinsky, F. Lin BNL, Upton, Long Island, New York
	The approach for the proposed National Synchrotron Light Source II to reach small transverse emittances is to deploy damping wigglers. In the ideal lattice the dispersion is zero in the straight sections, therefore the damping wigglers supply only damping effect. In reality the residual dispersion can be generated by the lattice errors, trim dipoles, and the insertion devices. We will discuss dispersion introduced by different sources and calculate the tolerances. Possible correction schemes will also be presented.

TUPMS086	Insertion Device R&D for NSLS-II	undulator, insertion, insertion-device, emittance	1368
	T. Tanabe D. A. Harder, G. Rakowsky, T. V. Shaftan, J. Skaritka BNL, Upton, Long Island, New York
	NSLS-II is a medium energy storage ring of 3GeV electron beam energy with sub-nm.rad horizontal emittance and top-off capability at 500mA. Damping wigglers will be used not only to reduce the beam emittance but also for broadband sources for users. Cryo-Permanent Magnet Undulators (CPMUs) are considered for hard X-ray linear device, and permanent magnet based Elliptically Polarized Undulators(EPUs) are for polarization control. Rigorous R&D plans have been established to pursue the performance enhancement of the above devices as well as building new types of insertion devices such as high temperature superconducting wiggler/undulators. This paper describes the details of these activities and discuss technical issues.

TUPAN033	DAΦ NE Setup and Performances During the Second FINUDA Run	luminosity, collider, injection, coupling	1457
	C. Milardi D. Alesini, M. E. Biagini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G. O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, M. Incurvati, P. Iorio, C. Ligi, F. Marcellini, C. Marchetti, G. Mazzitelli, L. Pellegrino, M. A. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov INFN/LNF, Frascati (Roma) J. D. Fox, D. Teytelman SLAC, Menlo Park, California E. Levichev, S. A. Nikitin, P. A. Piminov, D. N. Shatilov BINP SB RAS, Novosibirsk
	Beam operations on DAΦNE restarted on October 2006 after a four months shut-down to remove the KLOE experimental detector and to install the FINUDA one. This period has been also used for maintenance and implementation of several upgrades. In the first two months of operation the peak and integrated luminosity already exceeds the values obtained during the first FINUDA run by 20%. The DAΦNE goal is to deliver 1 fb-1 integrated luminosity by the end of May 2007. The collider performances during the run are presented together with the improvements obtained in terms of ring nonlinearities and beam dynamics coming from several collider modifications.

TUPAN035	Reduction of the Non-Linearities in the DAPHNE Main Rings Wigglers	multipole, octupole, simulation, quadrupole	1463
	S. Bettoni S. Guiducci, M. A. Preger, P. Raimondi, C. Sanelli INFN/LNF, Frascati (Roma)
	The wigglers of the DAPHNE main rings have been the main source of non-linearities for the beam dynamics in the collider. This paper describes a method to reduce the integrated odd multipoles (the even ones tend to vanish for the periodicity of the magnet) by alternatively displacing the magnetic axis of the poles to compensate the integrated odd multipoles in each half-period of the wiggler. In order to check the effectiveness of this approach, tracking studies have been performed. Tracking results have been used to tune the MAD model of the wiggler.

TUPAS067	Electron Cloud in the Wigglers of The Positron Damping Ring of the International Linear Collider	electron, dipole, damping, simulation	1808
	L. Wang F. Zimmermann CERN, Geneva
	Funding: Work supported by the U. S. Department of Energy under contract DE-AC02-76SF00515 The ILC positron damping ring comprises hundreds of meters of wiggler sections, where many more photons than in the arcs are emitted, and with the smallest beam-pipe aperture of the ring. A significant electron-cloud density can therefore be accumulated via photo-emission and via beam-induced multipacting. In field-free regions the electron-cloud build up may be suppressed by adding weak solenoid fields, but the electron cloud remaining in the wigglers as well as in the arc dipole magnets can still drive single-bunch and multi-bunch beam instabilities. This paper studies the electron-cloud formation in an ILC wiggler section for various scenarios, as well as its character, and possible mitigation schemes.

WEXAB02	Critical R&D Issues for the ILC Damping Rings and New Test Facilities	damping, emittance, electron, kicker	1945
	A. Wolski
	The damping rings for the International Linear Collider will be required to accept large beams from the electron and positron sources, and produce highly stable, very low emittance beams for tuning and operation of downstream systems. While many of the parameters for the damping rings are within range of storage rings presently operating, beams meeting the full quality and stability specifications have not been demonstrated. In addition, the requirements for some of the subsystems (for example, the injection and extraction kickers) push the limits of available technology. We discuss the principal goals and challenges of the damping rings research and development program, and the role that could be played by some proposed future damping rings test facilities.
	Slides

WEOAAB02	The Optimized Bunch Compressor for the International Linear Collider	linac, damping, emittance, linear-collider	1958
	S. Seletskiy P. Tenenbaum SLAC, Menlo Park, California
	The International Linear Collider (ILC) utilizes a two stage Bunch Compressor (BC) that compresses the RMS bunch length from 9 mm to 200 to 300 micrometers before sending the electron beam to the Main Linac. This paper reports on the new design of the optimized BC wiggler. It was reduced in length by more than 30 %. The introduction of nonzero dispersion slope in the BC wigglers enabled them to generate the required compression while having a small SR emittance growth, a tunability range of over a factor of 2 in each wiggler, and less than 3 % RMS energy spread throughout the entire system.
	Slides

WEPMS091	Conceptual Design of the NSLS-II RF Systems	damping, lattice, booster, injection	2550
	J. Rose A. Blednykh, W. Guo, P. Mortazavi, N. A. Towne BNL, Upton, Long Island, New York
	RF system requirements are derived from machine parameters and beam stability specifications. The conceptual design of the RF system for NSLS-II to meet these requirements is presented, consisting of 500 MHz superconducting main cavities, 1500 MHz SCRF harmonic cavities for bunch lengthening, and the RF power and cryogenic systems.

THPMS011	Design Considerations and Modeling Results for ILC Damping Ring Wigglers Based on the CESR-c Superconducting Wiggler	damping, linear-collider, electron, collider	3014
	J. A. Crittenden M. A. Palmer, J. T. Urban CLASSE, Ithaca
	Funding: Funding provided by NSF grant PHY-0202078 The ILC damping rings require wiggler magnets with large physical aperture and with excellent field quality to maintain the dynamic aperture of the rings. We consider two possible designs derived from the wigglers presently in operation at the Cornell Electron Storage Ring. Design optimization has been performed based on detailed tracking calculations of dynamic aperture and tune footprint in a full model of the damping ring. Results of finite-element modeling, transfer functions, and the accuracy of analytic models of the wiggler field will be discussed.

THPAN051	Update on the ILC DR Alternative Lattice Design	lattice, damping, dynamic-aperture, sextupole	3342
	Y. Sun J. Gao IHEP Beijing, Beijing Z. Y. Guo PKU/IHIP, Beijing
	In order to reduce the cost for ILC damping rings, an alternative lattice which is different from the baseline configuration design has been designed previously with modified FODO arc cells, and the total quadrupole and sextupole number has been reduced largely, compared with the baseline design. At the same time, to decrease the total cost involved in constructing access shafts needed to supply power, cryogenics etc. for the wigglers and other systems, the number of wiggler sections is decreased from 8 to 4, and further to 2. However, the momentum compaction of this lattice can not be tuned freely. In this paper, a new ILC damping ring lattice design with a variable momentum compaction will be presented, followed by the single particle dynamics associated studies. *ypsun@ihep.ac.cn

THPAN066	Improvements in FAKTOR2, a Code to Simulate Collective Effect of Electrons and Ions	electron, dipole, damping, vacuum	3375
	W. Bruns D. Schulte, F. Zimmermann CERN, Geneva
	Funding: Supported by the European Community under the 6th Framework Programme "Structuring the European Research Area". The electrostatic Particle in Cell code 'Faktor2' is extended to 3D, and is parallelised. Results for electron cloud buildup in end regions of damping ring dipoles for next generation linear colliders are presented.

THPAS001	Suppression of Terahertz Radiation in Electron Beams with Longitudinal Density Modulation	electron, simulation, gun, radiation	3507
	C. P. Neuman P. G. O'Shea UMD, College Park, Maryland
	Electron beams with periodic longitudinal density modulations may produce terahertz radiation in a linear accelerator. Terahertz radiation is useful for a wide range of applications and research interests. In other cases, it may be desirable to suppress unwanted terahertz radiation caused by unintended fluctuations of the electron beam. This study explores the possibility of using a wiggler to convert the density modulation to energy modulation. Previous studies by the author () have shown that energy modulation washes out of the beam as it is transported in a linear accelerator system. Thus, by converting density modulation to energy modulation and then letting it wash out, we will have suppressed density modulation in the beam and thus the possibility of unwanted terahertz radiation. Simulations are performed using PARMELA and other software codes. Results will provide a better understanding of the evolution of modulated electron beams and may provide a method to suppress unwanted terahertz radiation. Parameters in the simulations are chosen to correspond to existing accelerator systems so that the results may be used to support an experimental study. () Simulation of Longitudinally Modulated Electron Beams. C. P. Neuman and P. G. O'Shea. In 2006 Advanced Accelerator Concepts Workshop, AIP Conference Proceedings, 877, 621-627. Melville, AIP (2006).

FRXKI01	Superconducting Magnet Needs for the ILC	quadrupole, dipole, superconducting-magnet, undulator	3732
	J. C. Tompkins J. A. Clarke Cockcroft Institute, Warrington, Cheshire V. S. Kashikhin Fermilab, Batavia, Illinois M. A. Palmer CLASSE, Ithaca B. Parker BNL, Upton, Long Island, New York
	The ILC Reference Design Report will be completed early in 2007. The Magnet Systems Group was formed to translate magnetic field requirements into magnet designs and cost estimates for the Reference Design. As presently configured, the ILC will have more than 11,000 magnetic elements of which more than 1200 will be based on superconducting technology. This paper will describe the major superconducting magnet needs for the ILC as presently determined by the Magnet Systems Group and the leaders of the Area Systems Groups, responsible for beamline design. The superconducting magnet components include the Main Linac quadrupoles, the Positron Source undulators, the Damping Ring wigglers, and the complex array of Final Focus superconducting elements in the Beam Delivery System.
	Slides

FRPMS041	A Direct Electron Beam Energy Spread Measurement System for Beam Instability and FEL Research	electron, storage-ring, klystron, radiation	4045
	S. Huang, S. Huang PKU/IHIP, Beijing J. Li, Y. K. Wu FEL/Duke University, Durham, North Carolina
	Funding: Supported by US AFOSR MFEL grant #FA9550-04-01-0086. One of critical beam parameters for the storage ring based light sources is the energy spread of the electron beam. An accurate measurement of the energy spread remains a challenge. It is well known that the electrons with different energies can degrade the spontaneous emission spectrum of a two-wiggler system in an optical-klystron configuration. The reduced modulation in the spectrum can be used to determine the energy spread of the beam. This paper describes our newly developed energy spread measurement system employing a scanning spectrometer and a fast CCD. A fast CCD with a burst mode of operation is used so that dynamical changes of the energy spread from tens of microseconds to tens of milliseconds can be measured. This system will be used in the beam instability research and free-electron laser research. Together with compact wigglers, such a system can be developed as a dedicated beam diagnostic for storage rings and linacs.

FRPMS079	SUPPRESSION OF SECONDARY ELECTRON EMISSION USING TRIANGULAR GROOVED SURFACE IN THE ILC DIPOLE AND WIGGLER MAGNETS	electron, dipole, impedance, simulation	4234
	L. Wang K. L.F. Bane, C. Chen, T. M. Himel, M. Munro, M. T.F. Pivi, T. O. Raubenheimer, G. V. Stupakov SLAC, Menlo Park, California
	Funding: Work supported by the U. S. Department of Energy under contract DE-AC02-76SF00515 The development of an electron cloud in the vacuum chambers of high intensity positron and proton storage rings may limit machine performance. The suppression of electrons in a magnet is a challenge for the positron damping ring of the International Linear Collider (ILC) as well as the Large Hadron Collider. Simulation show that grooved surfaces can significantly reduce the electron yield in a magnet. Some of the secondary electrons emitted from the grooved surface return to the surface within a few gyrations, resulting in a low effective secondary electron yield (SEY) of below 1.0 A triangular surface is an effective, technologically attractive mitigation with a low SEY and a weak dependence on the scale of the corrugations and the external magnetic field. A chamber with triangular grooved surface is proposed for the dipole and wiggler sections of the ILC and will be tested in PEP-II in 2007. The strategy of electron cloud control in ILC and the optimization of the grooved chamber such as the SEY, impedance as well as the manufacturing of the chamber, are also discussed. SLAC-PUB-11933 & NIMA in publication