IPAC2011 - List of Keywords (wiggler)

Paper	Title	Other Keywords	Page
MOPS083	Update on Electron Cloud Mitigation Studies at Cesr-TA*	electron, positron, resonance, photon	796
	J.R. Calvey, M.G. Billing, J.V. Conway, G. Dugan, S. Greenwald, Y. Li, X. Liu, J.A. Livezey, J. Makita, R.E. Meller, M.A. Palmer, S. Santos, R.M. Schwartz, J.P. Sikora, C.R. Strohman CLASSE, Ithaca, New York, USA S. Calatroni, G. Rumolo CERN, Geneva, Switzerland K. Kanazawa, Y. Suetsugu KEK, Ibaraki, Japan M.T.F. Pivi, L. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by the US National Science Foundation (PHY-0734867) and Department of Energy (DE-FC02-08ER41538) Over the course of the past three years, the Cornell Electron Storage Ring (CESR) has been reconfigured to serve as a test facility for next generation particle accelerators. A significant part of this program has been the installation of several diagnostic devices to measure and quantify the electron cloud effect, a potential limiting factor in these machines. In particular, more than 30 Retarding Field Analyzers (RFAs) have been installed in CESR. These devices measure the local electron cloud density and energy distribution, and can be used to evaluate the efficacy of different cloud mitigation techniques. This paper will provide an overview of RFA results obtained at CesrTA over the past year, including measurements taken as function of bunch spacing and wiggler magnetic field. Understanding these results provides a great deal of insight into the behavior of the electron cloud.

TUPC050	Impedance Effects in the CLIC Damping Rings	impedance, damping, simulation, vacuum	1111
	E. Koukovini, K.S.B. Li, N. Mounet, G. Rumolo, B. Salvant CERN, Geneva, Switzerland
	Due to the unprecedented brilliance of the beams, the performance of the Compact Linear Collider (CLIC) damping rings is affected by collective effects. Single bunch instability thresholds based on a broad-band resonator model and the associated coherent tune shifts have been evaluated with the HEADTAIL code. Simulations performed for positive and negative values of chromaticity proved that higher order bunch modes can be potentially dangerous for the beam stability. This study also includes the effects of high frequency resistive wall impedance due to different coatings applied on the chambers of the wigglers for e-cloud mitigation and/or ultra-low vacuum pressure. The impact of the resistive-wall wake fields on the transverse impedance budget is finally discussed.

WEPC071	The Motion of an Electron in the Periodic Cusped Magnetic Fields	electron, focusing, betatron, coupling	2184
	G. Du, B.L. Qian, H. Wang National University of Defense Technology, Changsha, Kaifu District, People's Republic of China
	Funding: National High Technology Research and Development Program of P. R. China The motion and its stability of an electron in the periodic cusped magnetic fields have been analyzed theoretically and calculated numerically, as the stability could not be well predicted by the Mathieu’s equation to guide the design of the magnetic focusing system for the propagation of the sheet electron beams in the waveguides. The precise solution to the motion equations of the electron has been obtained by iteration. To validate the analytical solution and to evaluate the stability of the motion, numerical calculations have been carried out. And the results show that the analytical solution is reliable, and there is only one stable region in the (p₀, B₀) space, where the parameter p₀ is the period of the magnetic fields, and B₀ is the magnitude of the magnetic fields. Besides, the stability of the electron motion would become weaker while the initial distance between the electron and the axis becomes larger. These results are interesting to the area of the sheet-electron-beam microwave sources focused by the periodical cusped magnetic fields.

WEPC072	Insertion Devices and Beam Dynamics in the PLS-II Storage Ring	undulator, betatron, insertion, insertion-device	2187
	S. Chunjarean, S. Shin PAL, Pohang, Kyungbuk, Republic of Korea
	Effects of insertion devices like a superconducting multipole wiggler or an in-vacuum undulator on the beam dynamics of tghe upgraded Pohang Light Source (PLS-II) storage ring have been investigated. The narrow gap related to a short period length of the in-vacuum undulator or a transverse magnetic field roll off can impact the dynamic aperture or Touschek lifetime or injection efficiency. A three dimensional magnetic field model has been developed based on numerical data consisting of several coefficients in the Taylor expansion to accurately represent the actual field. In this paper, the magnetic field model has been produced with the differential algebraic code COSY INFINITY to formulate the Taylor transfer map for the wiggler and undulator. Frequency map analysis (FMA) and full 6D tracking has been performed to investigate resonances which may affect the particle stability and causing a reduction in injection efficiency.

WEPC077	Beam Based Measurements with the Modified Wigglers in DAΦNE	closed-orbit, octupole, multipole, simulation	2196
	S. Bettoni CERN, Geneva, Switzerland A. Drago, S. Guiducci, C. Milardi, M.A. Preger, P. Raimondi INFN/LNF, Frascati (Roma), Italy
	A novel idea to minimize the odd high order non-linearities in periodic magnets has been presented in other articles in the past. The optimization of this method on the wigglers of the main rings in DAΦNE has been performed by means of multipolar and tracking analysis. After the magnetic measurements on a spare wiggler confirmed the magnetic model used to optimize the DAΦNE wigglers, all the insertion devices in the main rings have been modified accordingly. In fall last year tune variation measurements as a function of closed orbit bumps around the wigglers confirmed the validity of the method. In this paper the beam based measurement results with the new configuration are discussed and compared with those obtained in the previous configurations.

THPC007	Laser Electron Interaction Simulation for the Femtosecond Bunch Slicing on SOLEIL Storage Ring	laser, electron, simulation, storage-ring	2918
	J.F. Zhang, M.-E. Couprie, M. Labat, A. Loulergue, A. Nadji SOLEIL, Gif-sur-Yvette, France
	The interaction of an electron bunch and a laser in a wiggler (modulator) to generate a femtosecond slice is simulated for the slicing project on SOLEIL storage ring, using a code based on Monte-Carlo method and GENESIS. The results from these two codes are consistent with the theoretical values. The maximum modulated energy of the electron bunch and the number of electrons above a certain limit are studied for different wiggler and laser parameters. The transport of the 6D distribution of the sliced bunch from the modulator to the radiators are simulated using AT (Accelerator Toolbox) and ELEGANT, with synchrotron radiation on and taking into account the collective effects of the sliced bunch core.

THPC028	A Proposal of Short X-ray Pulse Generation from Compressed Bunches by mm-wave iFEL in the SPring-8 Upgrade Plan	storage-ring, injection, electron, simulation	2969
	M. Masaki, K. Fukami, C. Mitsuda, T. Watanabe JASRI/SPring-8, Hyogo-ken, Japan
	In the SPring-8 upgrade plan, short pulse options are prepared for time-resolved experiments of pico-second order with high repetition rate. The best scenario is that selected bunches have equilibrium bunch length of 1 ps or less. A mm-wave storage-ring iFEL may be one possible solution for it. If resonant wavelength of the FEL is a few millimeters, which is about ten times longer than typical short bunch length of 0.3 mm corresponding to 1 ps, almost all electrons of a bunch can be confined in one valley of ponderomotive potentials formed by the FEL mechanism. The system consists of a helical wiggler with period length of several meters and a mm-wave resonator. Numerical simulations with coherent synchrotron radiation effect at bunch charge of 479 pC show that an ultra-short injection bunch is trapped in a mm-wave “bucket” and kept shorter than 1 ps (r.m.s.) even after twice the longitudinal damping time from the injection. The ultra-short bunches need to be injected from the XFEL linac. XFEL-to-Storage Ring beam transport line is designed to suppress dispersions which cause bunch lengthening. Tracking calculations show promising results for bunch qualities at the transport line.

THPC029	Ultra-low Emittance Light Source Storage Ring Consisting of 5-Bend Achromat Cells with Four Long Straight Sections	lattice, emittance, undulator, storage-ring	2972
	K. Tsumaki JASRI/SPring-8, Hyogo-ken, Japan
	The 6 GeV ultimate storage ring (USR) consisting of ten bend achromat cells has been proposed* and applied it to the SPring-8 Storage ring*. It has the same circumference as the SPring-8 storage ring, but does not have four long straight sections, where the SPring-8 storage ring does. The cell length is twice of that of the SPring-8 storage ring and the number of cell is half of the SPring-8. The photon beam line positions would deviate from those of the existing one. To avoid these problems, we designed a storage ring that has four long straight sections and same cell number. The cell is changed from ten bend achromat to five bend achromat and the cell length is shortened to 30 m which is the same length of the SPring-8 storage ring unit cell. The total ring consists of 44 five bend achromat cells and four long straight section cells. The emittance is 10⁴ pm and it will reduce to less than 50 pm by radiation damping of wigglers and undulators. The brightness is expected to be more than 10²2 phs/s/mm²/mrad² in 0.1%BW with 200 mA beam current. K. Tsumaki, N. Kumagai, NIM A 565 (2006) 394. ** K. Tsumaki, N. Kumagai, Proc. of EPAC06, THPLS035, p. 3362 (2006).

THPC064	Design Study of Low Emittance Lattice for Taiwan Light Source at 1 GeV	emittance, lattice, storage-ring, dynamic-aperture	3041
	C.Y. Lee NTHU, Hsinchu, Taiwan C.C. Chiang, P.J. Chou NSRRC, Hsinchu, Taiwan S.-Y. Lee IUCEEM, Bloomington, Indiana, USA
	We explored the possibility that the existing TLS storage ring to be operated at 1 GeV as a high brightness VUV light source after the completion of 3 GeV Taiwan Photon Source. To increase the spectral brightness, we need to reduce the beam emittance in the storage ring as much as possible. We first pursue the lowest emittance which is possible without altering the existing hardware configuration. The theoretical minimum emittance that could be achieved at 1 GeV for non-achromatic lattice is 3.8 nm-rad. However, this could not be achieved without introducing harmonic sextupoles. Preliminary results of low emittance lattice without harmonic sextupoles in TLS storage ring will be presented.

THPC075	Lattice Design for PEP-X Ultimate Storage Ring Light Source	emittance, lattice, dipole, dynamic-aperture	3068
	Y. Nosochkov, K.L.F. Bane, Y. Cai, R.O. Hettel, M.-H. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515. SLAC expertise in designing and operating high current storage rings and the availability of the 2.2-km PEP-II tunnel present an opportunity for building a next generation light source – PEP-X – that would replace the SPEAR3 storage ring in the future. The "baseline" design for PEP-X, with 164 pm-rad emittance at 4.5 GeV beam energy and a current of 1.5 A, was completed in 2010. As a next step in the study, a so-called "ultimate" PEP-X lattice having another order of magnitude reduction in emittance from the baseline design has been investigated. The beam emittance approaches the diffraction limited photon emittance for multi-keV photons, providing near maximum photon brightness and high coherence. In this design, the ring arcs contain seven-bend achromat cells yielding 29 pm-rad natural emittance and up to 9 insertion device straights per arc. Another factor of two emittance reduction is achieved with an 89.3-m damping wiggler installed in one of the six long straights. Details of the lattice design, the sextupole correction scheme, dynamic aperture simulations, and calculation of the intra-beam scattering effect and Touschek lifetime at a nominal 200-mA current are presented.

THPC151	The 65 mm Period Electromagnetic/Permanent Magnets Helical Undulator at SOLEIL	permanent-magnet, undulator, power-supply, electron	3239
	F. Marteau, P. Berteaud, F. Bouvet, L. Chapuis, M.-E. Couprie, J.P. Daguerre, T.K. El Ajjouri, J.-M. Filhol, P. Lebasque, J.L. Marlats, A. Mary, K. Tavakoli SOLEIL, Gif-sur-Yvette, France
	SOLEIL prepares a new 65 mm period Electromagnetic/Permanent Magnets Helical Undulator (EMPHU), with a rapid switching at 5 Hz of the polarization required for dichroïsm experiments. The vertical field Bz is produced by coils fed by a fast switching power supply (designed and built in house), with a maximum current of 350 A and a polarity switching time shorter than 100 ms. The coils consist of 25 stacked copper layers shaped by water jet cutting. The current flows in 16 layers and 9 of them are cooled with thermal drain to a water piping. 4 additional power supplies feed 2 types of correction coils for the dynamic compensation of the field integrals, besides the ones for the termination. 1.28 T remanence NdFeB permanent magnets generate the horizontal field Bx. Peak Bz and Bx in the helical configuration reach 0.24 T at 14.7 mm minimum gap. Thermal modelling and measurements aim at keeping the magnet temperature constant. The static magnetic configuration was optimised using the ID_Builder software and the trajectory were checked for insuring a good reproducibility of the photon beam pointing when sweeping from one helicity to the other.

THPC152	Measurements of SOLEIL Insertion Devices using Pulsed Wire Method	insertion, undulator, insertion-device, vacuum	3242
	M. Valléau, C. Benabderrahmane, M.-E. Couprie, O. Marcouillé, F. Marteau, J. Vétéran SOLEIL, Gif-sur-Yvette, France
	SOLEIL permanent magnets insertion devices are usually measured with a Hall probe in order to evaluate the electron angular deflexion, their deviation and the optical phase error, a figure of merit related to the quality of the insertion device radiation. A pulsed wire bench is developed at SOLEIL for reducing the measurement time of an undulator and for providing a measurement method without lateral access. A current pulse injected in a stretched wire inside the magnetic field area generates acoustic wave. The wire motion is detected by optical sensors whose signals are proportional to the local integral value. The signal-to-noise ratio of this method is often reduced due to several effects such as electronic noise, external and wire vibrations. However, following some hardware optimization it was possible to increase it up to almost 26 dB, making the method accurate and reproducible in order to realize efficient corrections. Measurements of first and second integral performed with Pulse wire, with Hall probe and with the electron beam are compared on three different types of insertions: an U18 in-vacuum cryogenic undulator, a HU60 APPLE-II undulator and a WSV50 in-vacuum wiggler.

THPC154	Shimming of the Dynamic Field Integrals of the BESSY II U125 Hybrid Undulator	undulator, permanent-magnet, electron, injection	3248
	J. Bahrdt, W. Frentrup, A. Gaupp, M. Scheer, I. Schneider, G. Wüstefeld HZB, Berlin, Germany
	Within a continuous program the BESSY II undulators are prepared for Topping-Up operation. The BESSY II U125 planar hybrid undulator has a period length of 125 mm and a pole width of only 60 mm. The horizontal defocusing of the 1.7 GeV e-beam may result in a significant reduction of the horizontal dynamic aperture, reducing the injection efficiency when injecting into the closed gap. The dynamic field integrals are derived from a 2D-Fourier decomposition of the 3D-field. An analytic description of the dynamic multipoles based on the Fourier coefficients is presented. Magic fingers have been installed in order to minimize the dynamic field integrals and to enlarge the good field region of the device.

THPC158	Field Optimization for Short Period Undulators	undulator, permanent-magnet, insertion, damping	3260
	P. Peiffer, A. Bernhard KIT, Karlsruhe, Germany R. Rossmanith Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany D. Schoerling CERN, Geneva, Switzerland
	Undulators dedicated to low energy electron beams, like Laser Wakefield Accelerators, require very short period lengths to achieve X-ray emission. However, at these short period lengths (~5 mm) it becomes difficult to reach magnetic field amplitudes that lead to a K parameter of ~1, which is generally desired. Room temperature permanent magnets and even superconductive undulators using Nb-Ti as conductor material have proven insufficient to achieve the desired field amplitudes. The superconductor Nb3Sn has the theoretical potential to achieve the desired fields. However, up to now it is limited by several technological challenges to much lower field values than theoretically predicted. Alternatives for higher fields would be to manufacture the poles of the undulator body from Holmium instead of iron or to use Nb-Ti wires with a higher superconductor/copper ratio. The advantages and challenges of the different options are compared in this contribution.

THPC160	A Superconducting Switch for Insertion Devices with Variable Period Length	insertion, insertion-device, power-supply, undulator	3266
	T. Holubek, T. Baumbach, S. Casalbuoni, S. Gerstl, A.W. Grau, M. Hagelstein, D. Saez de Jauregui Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany C. Boffo, W. Walter BNG, Würzburg, Germany
	Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they offer the possibility to enhance the tuning range and functionality significantly by period length switching. Period length switching can be realized by employing two or more individually powerable subsets of superconducting coils and by reversing the current in a part of the winding. So far, the first demonstration mock-up coil allowing period length tripling was fabricated and tested successfully. Here, we report on the feasibility of a superconducting switch operating at 4.2 K, immersed in a liquid Helium bath as well as under conduction cooled conditions.

THPC171	Performance of ID at ALBA	vacuum, undulator, storage-ring, insertion	3299
	J. Campmany, J. Marcos, V. Massana CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	The new synchrotron light source ALBA is currently being commissioned along with the first phase of beamlines. Up to 6 beamlines are using light produced by Insertion Devices. There are up to four types of IDs: 2 Apple-II undulators (EU62 and EU71) operating at low energies, one conventional wiggler (MPW80) operating in the range of 2 – 20 keV, two in-vacuum undulators (IVU21) operating in the range 5 – 30 keV and a superconducting wiggler (SCW30) operating in the range of 40 keV. Installation of the IDs has been done in two steps. First, the out-vacuum devices (EU62, EU71 and MPW80) have been mechanically installed. Initial commissioning of Storage Ring has been done with their gaps opened to maximum value. Then, their gap has been closed to study the effect in the beam dynamics. In the second step, the in-vacuum devices (both IVU21 and the SCW30) have been installed and tested. In this paper we present the first results and performances of the insertion devices obtained both in Site Acceptance Test and during the first months of commissioning with beam.

THPC172	Superconducting 119-pole Wiggler for ALBA Light Source	vacuum, electron, site, radiation	3302
	N.A. Mezentsev, S.V. Khrushchev, V.K. Lev, E.G. Miginsky, V.A. Shkaruba, V.M. Syrovatin, V.M. Tsukanov, A.A. Volkov BINP SB RAS, Novosibirsk, Russia J. Campmany, D. Einfeld CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	Budker INP of Siberian Branch of the Russian Academy of Science has designed, manufactured and tested 119-pole superconducting wiggler for ALBA CELLS light source. The period length and maximal field of the wiggler are 30 mm 2.2 Ò correspondingly. Pole gap and vertical aperture for electron beam are 12.6 mm and 8.5 mm, accordingly. The wiggler magnetic structure closely comes nearer to undulator structure as K-value is about 6. The wiggler cryostat is bath cryostat type with use of cryocoolers which provide zero liquid helium consumption for long period. In June, 2010 the wiggler has been successfully tested on ALBA site. Test results of the wiggler including magnetic measurement, quench training, cryogenic system behavior for various mode of operation are presented.

THPC175	Spectral Analysis of Arbitrary Strength Parameter for Various Insertion Devices	undulator, photon, insertion, insertion-device	3311
	S.D. Chen, T.M. Uen NCTU, Hsinchu, Taiwan C.-S. Hwang NSRRC, Hsinchu, Taiwan
	An insertion device (ID) with medium strength parameter was hard to be defined as a wiggler or an undulator. Usually, this kind of ID was classified according to the user’s definition and to select the spectrum calculation formula of wiggler or undulator. The spectrum calculation formula for wiggler or undulator is quite difference and consequently obtain a big different flux density by using the same strength parameter. So, it is no way that the spectrum calculation of them is consistent. Therefore, a universal formula will be developed for the spectrum analysis for the different kinds of insertion devices that is with large different strength parameter (deflection parameter). Consequently, a modified spectrum calculation formula of ID with medium strength parameter was studied by reviewing the difference of existing spectrum formulas. The familiar formula of calculating undulator spectrum was modified and can be used on ID with arbitrary strength parameter. The algorithm of formula modification was described. Some relative issue, like the effect of phase error and energy spread, and taper undulator were also discussed herein.

THPC179	Electron Beam Heating and Operation of the Cryogenic Undulator and Superconducting Wigglers at Diamond	electron, undulator, cavity, synchrotron	3323
	J.C. Schouten, E.C.M. Rial Diamond, Oxfordshire, United Kingdom
	Diamond Light Source has two superconducting wigglers and one cryocooled undulator installed serving three beam lines. The cryocooled undulator (cpmu) has been operating since August 2010 while the superconducting wigglers have been operating for more than 4 years (SCW-1) and 2 years (SCW-2). We will report on the first year of operation of the cpmu including details of its spectral output and cryogenic performance. Our experience of the cooling system and measures taken to ensure reliability and to minimize the risks of a prolonged downtime are also presented. The two superconducting wigglers are exposed to a high heat load due to the beam heating of the inner liner. Until recently this resulted in a much higher helium consumption than specified and so recently a new liner has been fitted to SCW-1 and new re-condensers to SCW-2. In addition a thermal bridge has been made between the RF tapers and the outer heat shield of both SCW-1 and SCW-2. The results of these improvements will be presented.

THPS009	Coherent Electron Cooling Demonstration Experiment	electron, ion, FEL, hadron	3442
	V. Litvinenko, S.A. Belomestnykh, I. Ben-Zvi, J. Bengtsson, A.V. Fedotov, Y. Hao, D. Kayran, G.J. Mahler, W. Meng, T. Rao, T. Roser, B. Sheehy, R. Than, J.E. Tuozzolo, G. Wang, 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
	Coherent electron cooling (CEC) is considered to be on of potential candidates capable of cooling high-energy, high-intensity hadron beams to very small emittances. It also has a potential to significantly boost luminosity of high-energy hadron-hadron and electron-hadron colliders. In a CEC system, a perturbation of the electron density caused by a hadron is amplified and fed back to the hadrons to reduce the energy spread and the emittance of the beam. Following the funding decision by DoE office of Nuclear Physics, we are designing and building coherent electron cooler for a proof-of-principle experiment at RHIC to cool 40 GeV heavy ion beam. In this paper, we describe the layout of the CeC installed into IP2 interaction region at RHIC. We present the design of the CeC cooler and results of preliminary simulations.

THPZ004	DAΦNE Tune-up for the KLOE-2 Experiment	luminosity, background, closed-orbit, coupling	3687
	C. Milardi, D. Alesini, M.E. Biagini, S. Bini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G.O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, M. Esposito, L.G. Foggetta, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, S.M. Liuzzo, F. Marcellini, 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), Italy S. Bettoni PSI, Villigen, Switzerland
	Funding: Work supported by the EuCARD research programme within the 'Assessment of Novel Accelerator Concepts' work package (ANAC-WP11). In its continuous evolution DAΦNE, the Frascati lepton collider, is starting a new run for the KLOE-2 experiment, an upgraded version of the KLOE one. A new interaction region, based on the high luminosity Crab-Waist collision scheme, has been designed, built and installed. Several machine subsystems have been revised according to innovative design concepts in order to improve beam dynamics. Collimators and shieldings have been upgraded in order to minimize the background rates on the detector during coasting as well as injection operation. A wide measurement campaign has been undertaken to verify and quantify the effect of the modifications and to tune-up the collider in view of the 3 years long data-taking foreseen to deliver ~5 fb-1 to the experiment.

Paper

Title

Other Keywords

Page

MOPS083

Update on Electron Cloud Mitigation Studies at Cesr-TA*

electron, positron, resonance, photon

796

J.R. Calvey, M.G. Billing, J.V. Conway, G. Dugan, S. Greenwald, Y. Li, X. Liu, J.A. Livezey, J. Makita, R.E. Meller, M.A. Palmer, S. Santos, R.M. Schwartz, J.P. Sikora, C.R. Strohman
CLASSE, Ithaca, New York, USA
S. Calatroni, G. Rumolo
CERN, Geneva, Switzerland
K. Kanazawa, Y. Suetsugu
KEK, Ibaraki, Japan
M.T.F. Pivi, L. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the US National Science Foundation (PHY-0734867) and Department of Energy (DE-FC02-08ER41538)
Over the course of the past three years, the Cornell Electron Storage Ring (CESR) has been reconfigured to serve as a test facility for next generation particle accelerators. A significant part of this program has been the installation of several diagnostic devices to measure and quantify the electron cloud effect, a potential limiting factor in these machines. In particular, more than 30 Retarding Field Analyzers (RFAs) have been installed in CESR. These devices measure the local electron cloud density and energy distribution, and can be used to evaluate the efficacy of different cloud mitigation techniques. This paper will provide an overview of RFA results obtained at CesrTA over the past year, including measurements taken as function of bunch spacing and wiggler magnetic field. Understanding these results provides a great deal of insight into the behavior of the electron cloud.

TUPC050

Impedance Effects in the CLIC Damping Rings

impedance, damping, simulation, vacuum

1111

E. Koukovini, K.S.B. Li, N. Mounet, G. Rumolo, B. Salvant
CERN, Geneva, Switzerland

Due to the unprecedented brilliance of the beams, the performance of the Compact Linear Collider (CLIC) damping rings is affected by collective effects. Single bunch instability thresholds based on a broad-band resonator model and the associated coherent tune shifts have been evaluated with the HEADTAIL code. Simulations performed for positive and negative values of chromaticity proved that higher order bunch modes can be potentially dangerous for the beam stability. This study also includes the effects of high frequency resistive wall impedance due to different coatings applied on the chambers of the wigglers for e-cloud mitigation and/or ultra-low vacuum pressure. The impact of the resistive-wall wake fields on the transverse impedance budget is finally discussed.

WEPC071

The Motion of an Electron in the Periodic Cusped Magnetic Fields

electron, focusing, betatron, coupling

2184

G. Du, B.L. Qian, H. Wang
National University of Defense Technology, Changsha, Kaifu District, People's Republic of China

Funding: National High Technology Research and Development Program of P. R. China
The motion and its stability of an electron in the periodic cusped magnetic fields have been analyzed theoretically and calculated numerically, as the stability could not be well predicted by the Mathieu’s equation to guide the design of the magnetic focusing system for the propagation of the sheet electron beams in the waveguides. The precise solution to the motion equations of the electron has been obtained by iteration. To validate the analytical solution and to evaluate the stability of the motion, numerical calculations have been carried out. And the results show that the analytical solution is reliable, and there is only one stable region in the (p₀, B₀) space, where the parameter p₀ is the period of the magnetic fields, and B₀ is the magnitude of the magnetic fields. Besides, the stability of the electron motion would become weaker while the initial distance between the electron and the axis becomes larger. These results are interesting to the area of the sheet-electron-beam microwave sources focused by the periodical cusped magnetic fields.

WEPC072

Insertion Devices and Beam Dynamics in the PLS-II Storage Ring

undulator, betatron, insertion, insertion-device

2187

S. Chunjarean, S. Shin
PAL, Pohang, Kyungbuk, Republic of Korea

Effects of insertion devices like a superconducting multipole wiggler or an in-vacuum undulator on the beam dynamics of tghe upgraded Pohang Light Source (PLS-II) storage ring have been investigated. The narrow gap related to a short period length of the in-vacuum undulator or a transverse magnetic field roll off can impact the dynamic aperture or Touschek lifetime or injection efficiency. A three dimensional magnetic field model has been developed based on numerical data consisting of several coefficients in the Taylor expansion to accurately represent the actual field. In this paper, the magnetic field model has been produced with the differential algebraic code COSY INFINITY to formulate the Taylor transfer map for the wiggler and undulator. Frequency map analysis (FMA) and full 6D tracking has been performed to investigate resonances which may affect the particle stability and causing a reduction in injection efficiency.

WEPC077

Beam Based Measurements with the Modified Wigglers in DAΦNE

closed-orbit, octupole, multipole, simulation

2196

S. Bettoni
CERN, Geneva, Switzerland
A. Drago, S. Guiducci, C. Milardi, M.A. Preger, P. Raimondi
INFN/LNF, Frascati (Roma), Italy

A novel idea to minimize the odd high order non-linearities in periodic magnets has been presented in other articles in the past. The optimization of this method on the wigglers of the main rings in DAΦNE has been performed by means of multipolar and tracking analysis. After the magnetic measurements on a spare wiggler confirmed the magnetic model used to optimize the DAΦNE wigglers, all the insertion devices in the main rings have been modified accordingly. In fall last year tune variation measurements as a function of closed orbit bumps around the wigglers confirmed the validity of the method. In this paper the beam based measurement results with the new configuration are discussed and compared with those obtained in the previous configurations.

THPC007

Laser Electron Interaction Simulation for the Femtosecond Bunch Slicing on SOLEIL Storage Ring

laser, electron, simulation, storage-ring

2918

J.F. Zhang, M.-E. Couprie, M. Labat, A. Loulergue, A. Nadji
SOLEIL, Gif-sur-Yvette, France

The interaction of an electron bunch and a laser in a wiggler (modulator) to generate a femtosecond slice is simulated for the slicing project on SOLEIL storage ring, using a code based on Monte-Carlo method and GENESIS. The results from these two codes are consistent with the theoretical values. The maximum modulated energy of the electron bunch and the number of electrons above a certain limit are studied for different wiggler and laser parameters. The transport of the 6D distribution of the sliced bunch from the modulator to the radiators are simulated using AT (Accelerator Toolbox) and ELEGANT, with synchrotron radiation on and taking into account the collective effects of the sliced bunch core.

THPC028

A Proposal of Short X-ray Pulse Generation from Compressed Bunches by mm-wave iFEL in the SPring-8 Upgrade Plan

storage-ring, injection, electron, simulation

2969

M. Masaki, K. Fukami, C. Mitsuda, T. Watanabe
JASRI/SPring-8, Hyogo-ken, Japan

In the SPring-8 upgrade plan, short pulse options are prepared for time-resolved experiments of pico-second order with high repetition rate. The best scenario is that selected bunches have equilibrium bunch length of 1 ps or less. A mm-wave storage-ring iFEL may be one possible solution for it. If resonant wavelength of the FEL is a few millimeters, which is about ten times longer than typical short bunch length of 0.3 mm corresponding to 1 ps, almost all electrons of a bunch can be confined in one valley of ponderomotive potentials formed by the FEL mechanism. The system consists of a helical wiggler with period length of several meters and a mm-wave resonator. Numerical simulations with coherent synchrotron radiation effect at bunch charge of 479 pC show that an ultra-short injection bunch is trapped in a mm-wave “bucket” and kept shorter than 1 ps (r.m.s.) even after twice the longitudinal damping time from the injection. The ultra-short bunches need to be injected from the XFEL linac. XFEL-to-Storage Ring beam transport line is designed to suppress dispersions which cause bunch lengthening. Tracking calculations show promising results for bunch qualities at the transport line.

THPC029

Ultra-low Emittance Light Source Storage Ring Consisting of 5-Bend Achromat Cells with Four Long Straight Sections

lattice, emittance, undulator, storage-ring

2972

K. Tsumaki
JASRI/SPring-8, Hyogo-ken, Japan

The 6 GeV ultimate storage ring (USR) consisting of ten bend achromat cells has been proposed* and applied it to the SPring-8 Storage ring**. It has the same circumference as the SPring-8 storage ring, but does not have four long straight sections, where the SPring-8 storage ring does. The cell length is twice of that of the SPring-8 storage ring and the number of cell is half of the SPring-8. The photon beam line positions would deviate from those of the existing one. To avoid these problems, we designed a storage ring that has four long straight sections and same cell number. The cell is changed from ten bend achromat to five bend achromat and the cell length is shortened to 30 m which is the same length of the SPring-8 storage ring unit cell. The total ring consists of 44 five bend achromat cells and four long straight section cells. The emittance is 10⁴ pm and it will reduce to less than 50 pm by radiation damping of wigglers and undulators. The brightness is expected to be more than 10²2 phs/s/mm²/mrad² in 0.1%BW with 200 mA beam current.
* K. Tsumaki, N. Kumagai, NIM A 565 (2006) 394.
** K. Tsumaki, N. Kumagai, Proc. of EPAC06, THPLS035, p. 3362 (2006).

THPC064

Design Study of Low Emittance Lattice for Taiwan Light Source at 1 GeV

emittance, lattice, storage-ring, dynamic-aperture

3041

C.Y. Lee
NTHU, Hsinchu, Taiwan
C.C. Chiang, P.J. Chou
NSRRC, Hsinchu, Taiwan
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

We explored the possibility that the existing TLS storage ring to be operated at 1 GeV as a high brightness VUV light source after the completion of 3 GeV Taiwan Photon Source. To increase the spectral brightness, we need to reduce the beam emittance in the storage ring as much as possible. We first pursue the lowest emittance which is possible without altering the existing hardware configuration. The theoretical minimum emittance that could be achieved at 1 GeV for non-achromatic lattice is 3.8 nm-rad. However, this could not be achieved without introducing harmonic sextupoles. Preliminary results of low emittance lattice without harmonic sextupoles in TLS storage ring will be presented.

THPC075

Lattice Design for PEP-X Ultimate Storage Ring Light Source

emittance, lattice, dipole, dynamic-aperture

3068

Y. Nosochkov, K.L.F. Bane, Y. Cai, R.O. Hettel, M.-H. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515.
SLAC expertise in designing and operating high current storage rings and the availability of the 2.2-km PEP-II tunnel present an opportunity for building a next generation light source – PEP-X – that would replace the SPEAR3 storage ring in the future. The "baseline" design for PEP-X, with 164 pm-rad emittance at 4.5 GeV beam energy and a current of 1.5 A, was completed in 2010. As a next step in the study, a so-called "ultimate" PEP-X lattice having another order of magnitude reduction in emittance from the baseline design has been investigated. The beam emittance approaches the diffraction limited photon emittance for multi-keV photons, providing near maximum photon brightness and high coherence. In this design, the ring arcs contain seven-bend achromat cells yielding 29 pm-rad natural emittance and up to 9 insertion device straights per arc. Another factor of two emittance reduction is achieved with an 89.3-m damping wiggler installed in one of the six long straights. Details of the lattice design, the sextupole correction scheme, dynamic aperture simulations, and calculation of the intra-beam scattering effect and Touschek lifetime at a nominal 200-mA current are presented.

THPC151

The 65 mm Period Electromagnetic/Permanent Magnets Helical Undulator at SOLEIL

permanent-magnet, undulator, power-supply, electron

3239

F. Marteau, P. Berteaud, F. Bouvet, L. Chapuis, M.-E. Couprie, J.P. Daguerre, T.K. El Ajjouri, J.-M. Filhol, P. Lebasque, J.L. Marlats, A. Mary, K. Tavakoli
SOLEIL, Gif-sur-Yvette, France

SOLEIL prepares a new 65 mm period Electromagnetic/Permanent Magnets Helical Undulator (EMPHU), with a rapid switching at 5 Hz of the polarization required for dichroïsm experiments. The vertical field Bz is produced by coils fed by a fast switching power supply (designed and built in house), with a maximum current of 350 A and a polarity switching time shorter than 100 ms. The coils consist of 25 stacked copper layers shaped by water jet cutting. The current flows in 16 layers and 9 of them are cooled with thermal drain to a water piping. 4 additional power supplies feed 2 types of correction coils for the dynamic compensation of the field integrals, besides the ones for the termination. 1.28 T remanence NdFeB permanent magnets generate the horizontal field Bx. Peak Bz and Bx in the helical configuration reach 0.24 T at 14.7 mm minimum gap. Thermal modelling and measurements aim at keeping the magnet temperature constant. The static magnetic configuration was optimised using the ID_Builder software and the trajectory were checked for insuring a good reproducibility of the photon beam pointing when sweeping from one helicity to the other.

THPC152

Measurements of SOLEIL Insertion Devices using Pulsed Wire Method

insertion, undulator, insertion-device, vacuum

3242

M. Valléau, C. Benabderrahmane, M.-E. Couprie, O. Marcouillé, F. Marteau, J. Vétéran
SOLEIL, Gif-sur-Yvette, France

SOLEIL permanent magnets insertion devices are usually measured with a Hall probe in order to evaluate the electron angular deflexion, their deviation and the optical phase error, a figure of merit related to the quality of the insertion device radiation. A pulsed wire bench is developed at SOLEIL for reducing the measurement time of an undulator and for providing a measurement method without lateral access. A current pulse injected in a stretched wire inside the magnetic field area generates acoustic wave. The wire motion is detected by optical sensors whose signals are proportional to the local integral value. The signal-to-noise ratio of this method is often reduced due to several effects such as electronic noise, external and wire vibrations. However, following some hardware optimization it was possible to increase it up to almost 26 dB, making the method accurate and reproducible in order to realize efficient corrections. Measurements of first and second integral performed with Pulse wire, with Hall probe and with the electron beam are compared on three different types of insertions: an U18 in-vacuum cryogenic undulator, a HU60 APPLE-II undulator and a WSV50 in-vacuum wiggler.

THPC154

Shimming of the Dynamic Field Integrals of the BESSY II U125 Hybrid Undulator

undulator, permanent-magnet, electron, injection

3248

J. Bahrdt, W. Frentrup, A. Gaupp, M. Scheer, I. Schneider, G. Wüstefeld
HZB, Berlin, Germany

Within a continuous program the BESSY II undulators are prepared for Topping-Up operation. The BESSY II U125 planar hybrid undulator has a period length of 125 mm and a pole width of only 60 mm. The horizontal defocusing of the 1.7 GeV e-beam may result in a significant reduction of the horizontal dynamic aperture, reducing the injection efficiency when injecting into the closed gap. The dynamic field integrals are derived from a 2D-Fourier decomposition of the 3D-field. An analytic description of the dynamic multipoles based on the Fourier coefficients is presented. Magic fingers have been installed in order to minimize the dynamic field integrals and to enlarge the good field region of the device.

THPC158

Field Optimization for Short Period Undulators

undulator, permanent-magnet, insertion, damping

3260

P. Peiffer, A. Bernhard
KIT, Karlsruhe, Germany
R. Rossmanith
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
D. Schoerling
CERN, Geneva, Switzerland

Undulators dedicated to low energy electron beams, like Laser Wakefield Accelerators, require very short period lengths to achieve X-ray emission. However, at these short period lengths (~5 mm) it becomes difficult to reach magnetic field amplitudes that lead to a K parameter of ~1, which is generally desired. Room temperature permanent magnets and even superconductive undulators using Nb-Ti as conductor material have proven insufficient to achieve the desired field amplitudes. The superconductor Nb3Sn has the theoretical potential to achieve the desired fields. However, up to now it is limited by several technological challenges to much lower field values than theoretically predicted. Alternatives for higher fields would be to manufacture the poles of the undulator body from Holmium instead of iron or to use Nb-Ti wires with a higher superconductor/copper ratio. The advantages and challenges of the different options are compared in this contribution.

THPC160

A Superconducting Switch for Insertion Devices with Variable Period Length

insertion, insertion-device, power-supply, undulator

3266

T. Holubek, T. Baumbach, S. Casalbuoni, S. Gerstl, A.W. Grau, M. Hagelstein, D. Saez de Jauregui
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
C. Boffo, W. Walter
BNG, Würzburg, Germany

Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they offer the possibility to enhance the tuning range and functionality significantly by period length switching. Period length switching can be realized by employing two or more individually powerable subsets of superconducting coils and by reversing the current in a part of the winding. So far, the first demonstration mock-up coil allowing period length tripling was fabricated and tested successfully. Here, we report on the feasibility of a superconducting switch operating at 4.2 K, immersed in a liquid Helium bath as well as under conduction cooled conditions.

THPC171

Performance of ID at ALBA

vacuum, undulator, storage-ring, insertion

3299

J. Campmany, J. Marcos, V. Massana
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

The new synchrotron light source ALBA is currently being commissioned along with the first phase of beamlines. Up to 6 beamlines are using light produced by Insertion Devices. There are up to four types of IDs: 2 Apple-II undulators (EU62 and EU71) operating at low energies, one conventional wiggler (MPW80) operating in the range of 2 – 20 keV, two in-vacuum undulators (IVU21) operating in the range 5 – 30 keV and a superconducting wiggler (SCW30) operating in the range of 40 keV. Installation of the IDs has been done in two steps. First, the out-vacuum devices (EU62, EU71 and MPW80) have been mechanically installed. Initial commissioning of Storage Ring has been done with their gaps opened to maximum value. Then, their gap has been closed to study the effect in the beam dynamics. In the second step, the in-vacuum devices (both IVU21 and the SCW30) have been installed and tested. In this paper we present the first results and performances of the insertion devices obtained both in Site Acceptance Test and during the first months of commissioning with beam.

THPC172

Superconducting 119-pole Wiggler for ALBA Light Source

vacuum, electron, site, radiation

3302

N.A. Mezentsev, S.V. Khrushchev, V.K. Lev, E.G. Miginsky, V.A. Shkaruba, V.M. Syrovatin, V.M. Tsukanov, A.A. Volkov
BINP SB RAS, Novosibirsk, Russia
J. Campmany, D. Einfeld
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

Budker INP of Siberian Branch of the Russian Academy of Science has designed, manufactured and tested 119-pole superconducting wiggler for ALBA CELLS light source. The period length and maximal field of the wiggler are 30 mm 2.2 Ò correspondingly. Pole gap and vertical aperture for electron beam are 12.6 mm and 8.5 mm, accordingly. The wiggler magnetic structure closely comes nearer to undulator structure as K-value is about 6. The wiggler cryostat is bath cryostat type with use of cryocoolers which provide zero liquid helium consumption for long period. In June, 2010 the wiggler has been successfully tested on ALBA site. Test results of the wiggler including magnetic measurement, quench training, cryogenic system behavior for various mode of operation are presented.

THPC175

Spectral Analysis of Arbitrary Strength Parameter for Various Insertion Devices

undulator, photon, insertion, insertion-device

3311

S.D. Chen, T.M. Uen
NCTU, Hsinchu, Taiwan
C.-S. Hwang
NSRRC, Hsinchu, Taiwan

An insertion device (ID) with medium strength parameter was hard to be defined as a wiggler or an undulator. Usually, this kind of ID was classified according to the user’s definition and to select the spectrum calculation formula of wiggler or undulator. The spectrum calculation formula for wiggler or undulator is quite difference and consequently obtain a big different flux density by using the same strength parameter. So, it is no way that the spectrum calculation of them is consistent. Therefore, a universal formula will be developed for the spectrum analysis for the different kinds of insertion devices that is with large different strength parameter (deflection parameter). Consequently, a modified spectrum calculation formula of ID with medium strength parameter was studied by reviewing the difference of existing spectrum formulas. The familiar formula of calculating undulator spectrum was modified and can be used on ID with arbitrary strength parameter. The algorithm of formula modification was described. Some relative issue, like the effect of phase error and energy spread, and taper undulator were also discussed herein.

THPC179

Electron Beam Heating and Operation of the Cryogenic Undulator and Superconducting Wigglers at Diamond

electron, undulator, cavity, synchrotron

3323

J.C. Schouten, E.C.M. Rial
Diamond, Oxfordshire, United Kingdom

Diamond Light Source has two superconducting wigglers and one cryocooled undulator installed serving three beam lines. The cryocooled undulator (cpmu) has been operating since August 2010 while the superconducting wigglers have been operating for more than 4 years (SCW-1) and 2 years (SCW-2). We will report on the first year of operation of the cpmu including details of its spectral output and cryogenic performance. Our experience of the cooling system and measures taken to ensure reliability and to minimize the risks of a prolonged downtime are also presented. The two superconducting wigglers are exposed to a high heat load due to the beam heating of the inner liner. Until recently this resulted in a much higher helium consumption than specified and so recently a new liner has been fitted to SCW-1 and new re-condensers to SCW-2. In addition a thermal bridge has been made between the RF tapers and the outer heat shield of both SCW-1 and SCW-2. The results of these improvements will be presented.

THPS009

Coherent Electron Cooling Demonstration Experiment

electron, ion, FEL, hadron

3442

V. Litvinenko, S.A. Belomestnykh, I. Ben-Zvi, J. Bengtsson, A.V. Fedotov, Y. Hao, D. Kayran, G.J. Mahler, W. Meng, T. Rao, T. Roser, B. Sheehy, R. Than, J.E. Tuozzolo, G. Wang, 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

Coherent electron cooling (CEC) is considered to be on of potential candidates capable of cooling high-energy, high-intensity hadron beams to very small emittances. It also has a potential to significantly boost luminosity of high-energy hadron-hadron and electron-hadron colliders. In a CEC system, a perturbation of the electron density caused by a hadron is amplified and fed back to the hadrons to reduce the energy spread and the emittance of the beam. Following the funding decision by DoE office of Nuclear Physics, we are designing and building coherent electron cooler for a proof-of-principle experiment at RHIC to cool 40 GeV heavy ion beam. In this paper, we describe the layout of the CeC installed into IP2 interaction region at RHIC. We present the design of the CeC cooler and results of preliminary simulations.

THPZ004

DAΦNE Tune-up for the KLOE-2 Experiment

luminosity, background, closed-orbit, coupling

3687

C. Milardi, D. Alesini, M.E. Biagini, S. Bini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G.O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, M. Esposito, L.G. Foggetta, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, S.M. Liuzzo, F. Marcellini, 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), Italy
S. Bettoni
PSI, Villigen, Switzerland

Funding: Work supported by the EuCARD research programme within the 'Assessment of Novel Accelerator Concepts' work package (ANAC-WP11).
In its continuous evolution DAΦNE, the Frascati lepton collider, is starting a new run for the KLOE-2 experiment, an upgraded version of the KLOE one. A new interaction region, based on the high luminosity Crab-Waist collision scheme, has been designed, built and installed. Several machine subsystems have been revised according to innovative design concepts in order to improve beam dynamics. Collimators and shieldings have been upgraded in order to minimize the background rates on the detector during coasting as well as injection operation. A wide measurement campaign has been undertaken to verify and quantify the effect of the modifications and to tune-up the collider in view of the 3 years long data-taking foreseen to deliver ~5 fb-1 to the experiment.