EPAC 2006 - List of Keywords

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

impedance

Paper	Title	Other Keywords	Page
MOPCH113	Re-bunching RF Cavities and Hybrid Quadrupoles for the RAL Front-end Test Stand (FETS)	quadrupole, linac, proton, CCL	306
	D.C. Plostinar CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon M.A. Clarke-Gayther CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
	The proposed FETS project at RAL will test a fast beam chopper in a 3.0 MeV H^- Medium Energy Beam Transport (MEBT) line. Space restrictions in the MEBT line place constraints on component length and drive the requirement to identify compact component configurations. A description is given of candidate re-bunching RF cavities and hybrid quadrupole designs. The cavity options considered are the space efficient Drift Tube Linac type cavity (DTL) with integrated quadrupoles, and the high shunt impedance Coupled Cavity Linac type cavity (CCL) with external quadrupoles. The advantages and disadvantages of both structures are discussed and a comprehensive comparison between the two is made enabling the best cavity geometry choice. The compact hybrid quadrupole configurations considered are the 'tandem' combination of permanent magnet (PMQ) and electro-magnetic (EMQ) types, and the concentric combination of PMQ and laminar conductor (Lambertson) EMQ types.

MOPCH118	Wideband Low-output-impedance RF System for the Second Harmonic Cavity in the ISIS Synchrotron	synchrotron, beam-loading, controls, acceleration	321
	Y. Irie JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken D. Bayley, G.M. Cross, I.S.K. Gardner, M.G. Glover, D. Jenkins, A. Morris, A. Seville, S.P. Stoneham, J.W.G. Thomason, T. Western CCLRC/RAL/ISIS, Chilton, Didcot, Oxon J.C. Dooling, D. Horan, R. Kustom, M.E. Middendorf, G. Pile ANL, Argonne, Illinois S. Fukumoto, M. Muto, T. Oki, A. Takagi, S. Takano KEK, Ibaraki
	Wideband low-output-impedance RF system for the second harmonic cavity in the ISIS synchrotron has been developed by the collaboration between Argonne National Laboratory, US, KEK, Japan and Rutherford Appleton Laboratory, UK. Low output impedance is realized by the feedback from plate output to grid input of the final triode amplifier, resulting in less than 30 ohms over the frequency range of 2.7 - 6.2 MHz which is required for the second harmonic cavity. The vacuum tubes in the driver and final stages are both operated in class A, and a grid bias switching system is used on each tube to avoid unnecessary plate dissipations during a non-acceleration cycle. High power test was performed with a ferrite-loaded second harmonic cavity, where the bias current was swept at 50 Hz repetition rate. The maximum voltage of 12kV peak per accelerating gap was obtained stably at earlier period of an acceleration cycle. A beam test with this system is planned at the ISIS synchrotron in order to investigate how the low impedance system works under heavy beam loading conditions, and is capable of mitigating the space charge detuning at the RF trapping stage.

MOPCH153	Peak Field Optimization for the Superconducting CH Structure	simulation, linac, cryogenics, GSI	415
	H. Liebermann, H. Podlech, U. Ratzinger IAP, Frankfurt-am-Main
	The Cross-Bar H-type (CH) cavity is a multi-gap drift tube structure operated in the H-210 mode which has been developed at the IAP Frankfurt and in collaboration with GSI. Based on detailed numerical simulations a 19 cell prototype cavity from massive Nb was realised. For optimization of the magnetic and electric peak fields, detailed numerical simulations with CST MicroWave Studio have been performed. After successful experiments on the superconducting prototype cavity calculations about improved drift tube geometries with respect to field emission took place. Additionally, the stem geometry was further improved by simulations.

MOPCH182	The JLAB Ampere-class Cryomodule Conceptual Design	damping, FEL, coupling, BBU	490
	R.A. Rimmer, G. Ciovati, E. Daly, T. Elliott, J. Henry, W.R. Hicks, P. Kneisel, S. Manning, R. Manus, J.P. Preble, K. Smith, M. Stirbet, L. Turlington, L. Vogel, H. Wang, K. Wilson, G. Wu Jefferson Lab, Newport News, Virginia
	For the next generation of compact high-power FELs a new cryomodule is required that is capable of accelerating up to Ampere levels of beam current. Challenges include strong HOM damping, high HOM power and high fundamental-mode power (in operating scenarios without full energy recovery). For efficient use of space a high real-estate gradient is desirable and for economic operation good fundamental-mode efficiency is important. The technology must also be robust and should be based on well-proven and reliable technologies. For Ampere-class levels of beam current both halo interception and beam break-up (BBU) are important considerations. These factors tend to drive the designs to lower frequencies where the apertures are larger and the transverse impedances are lower. To achieve these goals we propose to use a compact waveguide-damped multi-cell cavity packaged in an SNS-style cryomodule.

MOPLS066	Direct Measurement of Geometric and Resistive Wakefields in Tapered Collimators for the International Linear Collider	SLAC, emittance, linear-collider, collider	697
	N.K. Watson, D. Adey, M.C. Stockton Birmingham University, Birmingham D.A.-K. Angal-Kalinin, C.D. Beard, J.L. Fernandez-Hernando, F. Jackson CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire R. Arnold, R.A. Erickson, C. Hast, T.W. Markiewicz, S. Molloy, M.C. Ross, S. Seletskiy, A. Seryi, Z. Szalata, P. Tenenbaum, M. Woodley, M. Woods SLAC, Menlo Park, California R.J. Barlow, A. Bungau, R.M. Jones, G.Yu. Kourevlev, A. Mercer UMAN, Manchester D.A. Burton, J.D.A. Smith, A. Sopczak, R. Tucker Lancaster University, Lancaster C. Densham, G. Ellwood, R.J.S. Greenhalgh, J. O'Dell CCLRC/RAL, Chilton, Didcot, Oxon Y.K. Kolomensky UCB, Berkeley, California M. Kärkkäinen, W.F.O. Müller, T. Weiland TEMF, Darmstadt N. Shales Microwave Research Group, Lancaster University, Lancaster M. Slater University of Cambridge, Cambridge I. Zagorodnov DESY, Hamburg F. Zimmermann CERN, Geneva
	Precise collimation of the beam halo is required in the ILC to prevent beam losses near the interaction region that could cause unacceptable backgrounds for the physics detector. The necessarily small apertures of the collimators lead to transverse wakefields that may result in beam deflections and increased emittance. A set of collimator wakefield measurements has previously been performed in the ASSET region of the SLAC LINAC. We report on the next phase of this programme, which is carried out at the recently commissioned End Station A test facility at SLAC. Measurements of resistive and geometric wakefields using tapered collimators are compared with model predictions from MAFIA and GdfidL and with analytic calculations.

MOPLS070	Numerical Calculations of Collimator Insertions	simulation, insertion, SLAC, CERN	709
	C.D. Beard CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire J.D.A. Smith Cockcroft Institute, Warrington, Cheshire
	A series of collimator spoilers have been designed and manufactured for testing in the ESA wakefield tests. The purpose of the tests is a benchmarking exercise to assist with the understanding into the causes of wakefields due to spoiler profile and materials. Simulations of the spoiler designs have been used to understand the likely effects that would be observed with the beam tests. Simulations of these collimator insertions have been carried out in MAFIA and GDFIDL, and a comparison of the results completed. The wake potential has been measured, and the corresponding loss factor and kick factors have been calculated. The results from the simulations are discussed in this report.

MOPLS071	TDR Measurements in support of ILC Collimator Studies	simulation, electron, synchrotron, SLAC	712
	C.D. Beard, P.A. Corlett, A.J. Moss, J.H.P. Rogers CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire R.M. Jones Cockcroft Institute, Warrington, Cheshire
	In this report the outcome of the "wire method" cold test, experimental results and their relevance toward the ILC set-up is considered. A wire is stretched through the centre of a vessel along the axis that the electron beam would take, and a voltage pulse representing the electron bunch is passed along the wire. The parasitic mode loss parameter from this voltage can then be measured. The bunch length for the ILC is 0.3mm, requiring a pulse rise time of ~1ps. The fastest rise time available for a time domain reflectrometry (TDR) scope is ~10ps. Reference vessels have been examined to evaluate the suitability of the test gear at comparable bunch structures to the ILC.

MOPLS085	Experience with a Zero Impedance Vacuum Flange at He Super-Leak Temperature for the ILC	vacuum, KEK, ion, target	753
	H. Matsumoto, F. Furuta, I.H. Inoue, K. Saito, S.N. Sakamoto, K. Ueno KEK, Ibaraki
	Several tens of thousands of vacuum flanges will be used in the construction of the ILC. So the reliability and large scale reproducibility of these elements are important issue. To arrive at a standardized vacuum flange, a new design of a unisex flange has been developed. This important component has to serve in two roles at He-super-leak temperature; both as an rf seal and as a vacuum seal. We chose the unisex type with a 90-degree sharp edge forming the seal. The design is a modification of the DESY S-band rectangular waveguide flange. The variation in flatness between the flange and gasket along the inside wall is within 50 micrometer. This should present zero impedance for a bunched beam and for rf power. The He-super-leak performance was measured using the "build up method", i.e.the test was carried out for three hours at 2 degrees Kelvin. The measured He leak rate was below 1·10^-13 Atm*cc/sec for a test flange after three successive tests. We describe the design concept and the operational experience at various rf frequencies. These span the frequency range corresponding to warm and cold accelerators.

MOPLS090	Design of a Strip-line Extraction Kicker for CTF3 Combiner Ring	kicker, simulation, CTF3, power-supply	762
	I. Rodriguez, F. Toral CIEMAT, Madrid L. García-Tabarés CEDEX, Madrid A. Ghigo, F. Marcellini INFN/LNF, Frascati (Roma)
	The new CLIC test facility (CTF3) is the latest stage to prove the technical feasibility of the CLIC project. An extraction kicker is necessary for the combiner ring, and it will be a strip-line type device due to lower coupling impedances and straightforward fabrication. The field uniformity together with a correct beam dynamics are the most challenging issues of this design. The main parameters of the kicker are analytically calculated using standard analytic formulae. The numeric modelling and simulation of several possible straight sections are reported, and the characteristic impedance is matched with the 50 Ω load. The field homogeneity, the kick angle and the scattering parameters are calculated in a 3D finite element model. Several manufacturing issues for the first prototype are also outlined.

MOPLS143	Suppression of Secondary Emission in a Magnetic Field using Sawtooth Surface	electron, dipole, damping, quadrupole	897
	L. Wang, T.O. Raubenheimer, G.V. Stupakov SLAC, Menlo Park, California
	The effect of surface roughness on the secondary electron emission from a sawtooth surface in a magnetic field under electron bombardment is investigated using a Monte-Carlo method. Some of the secondary electrons emitted from the sawtooth surface return to the surface within their first few gyrations, resulting in low effective secondary electron yield. A sawtooth surface in magnetic field can significantly reduce the secondary emission yield below the multipacting threshold.

TUOCFI03	RF Cavity with Co-based Amorphous Core	acceleration, synchrotron, controls, feedback	983
	M. Kanazawa, T. Misu, A. Sugiura NIRS, Chiba-shi K. Katsuki Toshiba, Yokohama
	A compact acceleration cavity has been developed with new Co-based amorphous cores, which will be used in a dedicated synchrotron for cancer therapy. This core has high permeability that makes the cavity length short, and the cavity with no tuning system is possible with low Q-value of about 0.5. An acceleration cavity consists of two units that have a single acceleration gap at the center, and at the both side of the gap there are quarter wave coaxial resonators. Considering the requirements for easy operation, a transistor power supply was used instead of commonly used tetrode in the final stage RF amplifier. Each resonator has maximum impedance about 400? at 3MHz, and has been attached with 1:9 impedance transformer. In the frequency range from 0.4 to 8 MHz, the acceleration voltage of more than 4kV can be obtained with total input RF power of 8kW. With these performances, the cavity length is short as 1.5m. In this paper the structure of the cavity and their tested high power performances are presented.
	Transparencies

TUODFI01	The Final Collimation System for the LHC	LHC, collimation, insertion, proton	986
	R.W. Assmann, O. Aberle, G. Bellodi, A. Bertarelli, C.B. Bracco, H.-H. Braun, M. Brugger, S. Calatroni, R. Chamizo, A. Dallocchio, B. Dehning, A. Ferrari, P. Gander, A. Grudiev, E.B. Holzer, J.-B. Jeanneret, J.M. Jimenez, M. Jonker, Y. Kadi, K. Kershaw, J. Lendaro, J. Lettry, R. Losito, M. Magistris, A.M. Masi, M. Mayer, E. Métral, R. Perret, C. Rathjen, S. Redaelli, G. Robert-Demolaize, S. Roesler, F. Ruggiero, M. Santana-Leitner, P. Sievers, M. Sobczak, E. Tsoulou, V. Vlachoudis, Th. Weiler CERN, Geneva I. Baishev, I.L. Kurochkin IHEP Protvino, Protvino, Moscow Region
	The LHC collimation system has been re-designed over the last three years in order to address the unprecedented challenges that are faced with the 360 MJ beams at 7 TeV. The layout of the LHC has now been fixed and a final approach for collimation and cleaning has been adopted. In total 132 collimator locations have been reserved in the two LHC rings and can be installed in a phased approach. Ninety collimators of five different types will be available for initial beam operation. The system has been fully optimized for avoiding quenches of super-conducting magnets during beam losses and for sufficient survival of beamline components against radioactive dose. The phased approach for LHC collimation is described, the various collimators and their functionalities are explained, and the expected system performance is summarized.
	Transparencies

TUPCH006	A Wideband Intercepting Probe for the TRIUMF Cyclotron	cyclotron, simulation, electron, linac	1001
	V.A. Verzilov, D. Cameron, D.T. Gray, S. Kellogg, M. Minato, W.R. Rawnsley TRIUMF, Vancouver
	An intercepting probe for the TRIUMF cyclotron capable of measuring the phase and time structure of the circulating beam was designed, manufactured, installed into the tank and tested. A model of the probe head in the form of a 50 Ohm parallel plate transmission line was developed and simulated to operate up to 2 GHz. Thermal simulations show that the probe can withstand at least 500 nA of average current for the 500 MeV beam. In laboratory tests the probe demonstrated a bandwidth in excess of 1 GHz. The probe was mounted on a 3 m long drive and is capable of travelling over 0.5 m at an angle of 27 degree w.r.t. the cyclotron radius. The signals extracted from the probe are processed by a pair of diplexers, where low frequency and high frequency components are separated. The low frequency signal is directed to our standard electronics for processing and provides both dc current and a time of flight signal with a rise time of about 100 ns. At the high frequency output a signal-to-noise ratio of about 4 at 250 nA average current and 0.1 % duty cycle was measured in the presence of rf background from the cyclotron resonators. A bunch time structure as short as 1 ns was resolved.

TUPCH059	Dual-mode Beam Current Monitor	pick-up, feedback, injection, shielding	1145
	S. Ninomiya, T. Adachi, S. Fukumoto KEK, Ibaraki S.H. Hatori, T. Kurita WERC, Tsuruga , Fukui
	A new type HEREWARD-transformer is developed. The original scheme connects pickup coil to the low impedance input of the amplifier to increase the time constant of the transformer. The new scheme employs negative impedance circuit which realizes perfect cancellation of the coil resistance. Therefore DC component of the beam current can be observed. Since number of winding of the pick up coil is only 100-turns, therefore by using the original scheme with a fast operational amplifier, the transformer can be operated at fast CT mode. Thus the dual mode operation can be realized by single core; the first mode is the slow beam intensity monitor, and the second is a fast response transformer. This operation mode realizes an accurate observation of the beam injection process. In order to make installation easy, the core is divided into two pieces. The magnetic shield from bending field is also installed. This monitor is developed at KEK, and installed into the accelerator at the WAKASA WAN Energy Research Center.

TUPCH078	BPM Design for the ALBA Synchrotron	booster, vacuum, storage-ring, pick-up	1190
	F. Pérez, A. Olmos ALBA, Bellaterra T.F. Günzel ESRF, Grenoble
	ALBA is a 3 GeV, low emittance, 3rd generation synchrotron light source that is in the construction phase in Cerdanyola, Spain. Vertical beam sizes down to a few microns will require beam stabilities on the submicron level. The BPM has to be designed in order to provide reliable and accurate beam position readings. Simulation and computational codes have been used to optimise, for a given vacuum chamber dimension, the BPM design. The optimisation has taken into account the usual sensitivity and intrinsic resolution parameters, but as well, the wakefield loss factor of the buttons. Due to the small vertical vacuum chamber dimension and the high design current, the beam power deposited in the buttons is becoming a concern due to the thermal deformation effects that can introduce errors at the submicron level. A compromise between a higher intrinsic resolution from one side, and a low power deposited by the beam in the buttons from the other, define the final buttons dimensions.

TUPCH099	Development of HOM Damped Copper Cavity for the ESRF	simulation, damping, ESRF, LEP	1244
	N. Guillotin, J. Jacob, V. Serriere ESRF, Grenoble
	At the ESRF, HOM driven longitudinal coupled bunch instabilities are currently avoided up to the nominal beam current of 200 mA by precisely controlling the cavity temperatures and thereby the HOM frequencies of the existing five-cell copper cavities. A bunch-by-bunch feedback is presently being commissioned in order to increase the maximum stored current. In parallel, normal conducting strongly HOM damped cavities are under study to possibly replace the five-cell cavities. The design is based on a scaling of the single cell EU cavity: a pillbox geometry with nose cones and three attached ridged waveguides loaded by ferrites for effective HOM damping. We report on the electromagnetic simulation making use of the 3D codes HFSS and GdfidL. They allowed optimizing the shape of both cavity and dampers, including electromagnetic absorbing material with frequency dependent parameters. E. Weihreter et al. A Ridged Circular Waveguide Ferrite Load for Cavity HOM Damping, this conference.

TUPCH114	A Ridged Circular Waveguide Ferrite Load for Cavity HOM Damping	vacuum, damping, simulation, radiation	1280
	E. Weihreter, V. Duerr, F. Marhauser BESSY GmbH, Berlin
	A normal conducting HOM damped 500 MHz prototype cavity has been tested with three tapered circular double ridged waveguide to coaxial transitions as HOM couplers, featuring maximum longitudinal and transverse HOM impedances below 5 kOhm and 200 kOhm/m respectively. Numerical simulations indicate that these impedance levels can be further reduced by more than a factor of 3 using homogeneous circular double ridged waveguides for improved coupling to the HOMs. In the present paper the layout of an optimised homogeneous waveguide with "in vacuum" ferrite tiles is presented, including mechanical and thermal design considerations. Low power reflectrometry measurements demonstrate good matching of a prototype load, and high power tests of the ferrite absorber elements indicate that the waveguide load is well suited for the cavity HOM power levels present in state of art 3rd generation SR sources.

TUPCH115	Status of the 70 MeV, 70 mA CH Proton-DTL for FAIR	quadrupole, GSI, proton, antiproton	1283
	G. Clemente, H. Podlech, U. Ratzinger, R. Tiede IAP, Frankfurt-am-Main L. Groening GSI, Darmstadt S. Minaev ITEP, Moscow
	The CH-type cavity shows promising features in the low and medium beta range: its high accelerator gradient and the high level of shunt impedance together with the compact transverse dimensions make this new cavity a good candidate for proton acceleration up to 100 MeV. That's why GSI has decided to base the new high current proton injector for the new FAIR facility on that structure: the operating frequency will be 352 MHz with an injection energy of 3 MeV. In order to improve the technical experience on this new kind of structure, IAP has built a model consisting of 8 equidistant gaps for a total cavity-length of 60 cm. Several design options with respect to welding, alignement, cooling and RF joints were studied and compared each other. A new concept for the end-cells geometry will result in the desired flatness of the electric field along the cavity axis and, at the same time, allow effective integration of internal quadruple lenses. Finally, the electric quadruple content of CH-structure gaps is listed in dependence on the geometry of the cell.

TUPCH124	Improvement of Co-based Amorphous Core for Untuned Broadband RF Cavity	acceleration, LEFT, heavy-ion, synchrotron	1304
	A. Sugiura, M. Kanazawa, T. Misu, S. Yamada NIRS, Chiba-shi K. Katsuki, T. Kusaka, K. Sato Toshiba, Yokohama
	We have developed a cobalt-based amorphous core as a new magnetic-alloy (MA) core for the loaded RF cavity. Because of its permeability found to be approximately twice as high as that of FINEMET, this MA core is an excellent candidate for constructing a compact broadband RF cavity with less power consumption. In this report, we present our recent studies of the Co-based amorphous core's physical properties and performance. Improvement of the new core coated by new materials surface of ribbon is also described.

TUPCH131	High Power Test of MA Cavity for J-PARC RCS	synchrotron, proton, acceleration, power-supply	1322
	M. Yamamoto, M. Nomura, A. Schnase, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii KEK, Ibaraki K. Hasegawa JAEA, Ibaraki-ken
	We have been constructing the RF system for the J-PARC RCS. Almost all of the power supplies and the tube amplifiers have been constructed, and the cavities are under construction. All of them are tested at the experimental hall before installing into the J-PARC RCS building. We test the hybrid cavity scheme to realize the optimum cavity Q-value. The results of the test are described.

TUPCH137	Design of the RF System for 30 MeV Cyclotron	cyclotron, simulation, vacuum, coupling	1340
	I.S. Jung, D.H. An, J.-S. Chai, H.B. Hong, S.S. Hong, M.G. Hur, H.S. Jang, J. Kang, J.H. Kim, Y.-S. Kim, M.Y. Lee, T.K. Yang KIRAMS, Seoul K.H. Kwon SKKU, Seoul
	LAD (Lab. of Accelerator Development) in KIRAMS (Korea Institute of Radiological & Medical Sciences) developed 13MeV medical cyclotron, named by KIRAMS-13, for PET (Positron Emission Tomography) in 2001. Now, KIRAMS-13 is widespread in Korea through the national project, "Development of Cyclotron and FDG Synthesis module." But, there is just one cyclotron for SPECT(Single Photon Emission Computed Tomography) in Korea, which is made by IBA, Belgium. If some problems are happened, we should shut off the cyclotron until IBA engineer fixes them. So, we decide to develop a 30MeV cyclotron, named KIRAMS-30, which has high-performance compared with existing commercial cyclotrons and will install this machine to radioactive isotopes production and researches in Advanced Radiation Technology Institute. In this paper, we design RF system, such as cavity, power coupler, and so on. At design of RF components, we consider mechanical stability, RF heating and cooling, arcing and multipacting, low maintenance. We simulate KIRAMS-30 with MWS (MicroWave Studio) and present simulation results.

TUPCH200	Amplitude Linearizers for PEP-II 1.2 MW Klystrons and LLRF Systems	klystron, controls, feedback, power-supply	1480
	D. Van Winkle, J. Browne, J.D. Fox, T. Mastorides, C.H. Rivetta, D. Teytelman SLAC, Menlo Park, California
	The PEP-II B-factory has aggressive current increases planned for luminosity through 2008. At 2.2 A (HER) on 4 A (LER) currents, longitudinal growth rates will exceed the damping rates achievable in the existing low level RF and longitudinal low mode feedback systems. Klystron gain non-linearity has been shown to be a key contributor to these increased growth rates through time domain non-linear modeling and machine measurements. Four prototype klystron amplitude modulation linearizers have been developed to explore improved linearity in the LLRF system. The linearizers operate at 475 MHz with 15 dB dynamic range and 1 MHz linear control bandwidth. Results from lab measurements and high current beam tests are presented. Future development progress and production designs are detailed.

TUPLS008	A new HOM Water Cooled Absorber for the PEP-II B-factory Low Energy Ring	dipole, quadrupole, scattering, coupling	1499
	M. Kosovsky, N. Kurita, A. Novokhatski, J. Seeman, S.P. Weathersby SLAC, Menlo Park, California
	At high currents and small bunch lengths beam line components in the PEP-II B-factory experience RF induced heating from higher order RF modes (HOMs) produced by scattered intense beam fields. A design for a passive HOM water cooled absorber for the PEP-II low energy ring is presented. This device is to be situated near HOM producing beamline components such as collimators and provide HOM damping for dipole and quadrupole modes while minimizing impedance to the beam. We present a method of optimizing the impedance characteristics of such devices through the evaluation of loss factors and absorber effectiveness for specific modes using scattering parameter and wakefield analysis.

TUPLS009	Design and Tests of New Fast Kickers for the DAFNE Collider and the ILC Damping Rings	kicker, injection, damping, positron	1502
	D. Alesini, S. Guiducci, F. Marcellini, P. Raimondi INFN/LNF, Frascati (Roma)
	In this paper we illustrate the design of new, fast stripline kickers to inject or extract bunches in electron/positron rings. The kickers have been designed for the injection upgrade of the Phi-factory DAFNE and as injection/extraction devices for the International Linear Collider (ILC) damping rings. The design is based on tapering the striplines in order to simultaneously obtain low impedance and an excellent uniformity of the deflecting field. The design has been done using 2D and 3D electromagnetic codes such as Superfish and HFSS. High voltage test results on prototypes are also shown.

TUPLS011	The Beam Screen for the LHC Injection Kicker Magnets	LHC, kicker, injection, vacuum	1508
	M.J. Barnes, F. Caspers, L. Ducimetière, N. Garrel, T. Kroyer CERN, Geneva
	The two LHC injection kicker magnet systems must each produce a kick of 1.2 T.m with a flattop duration variable up to 7.86 μs, and rise and fall times of less than 0.9 μs and 3 μs, respectively. Each system is composed of four 5 Ω transmission line kicker magnets with matched terminating resistors and pulse forming networks (PFN). The LHC beam has a high intensity, hence a beam screen is required in the aperture of the magnets This screen consists of a ceramic tube with conducting "stripes" on the inner wall. The stripes provide a path for the image current of the beam and screen the magnet ferrites against Wake fields. The stripes initially used gave adequately low beam impedance however stripe discharges occured during pulsing of the magnet: hence further development of the beam screen was undertaken. This paper presents options considered to meet the often conflicting needs for low beam impedance, shielding of the ferrite, fast field rise time and good electrical and vacuum behaviour.

TUPLS114	An Improvement of Matching Circuit of RF Kicker Electrodes	extraction, controls, feedback, kicker	1771
	T. Kurita, S. Fukumoto, S.H. Hatori WERC, Tsuruga , Fukui S. Ninomiya KEK, Ibaraki
	Beam extraction system at accelerator of The Wakasa Wan Energy Research Center employs RF knockout technology. Narrow band RF noise is applied to the transverse kicker electrodes to increase betatron amplitude of the beam. Recently some improvements of the beam extraction system are introduced: To improve the shape of the spill, a feedback control of noise amplitude is introduced. The feedback control system works as an attenuator, therefore it is necessary to enhance the noise amplitude of the kicker electrodes to obtain agreeable effect on the spill shape. In order to obtain a higher voltage, we revamp the matching circuit at the electrodes. By introducing the resonating characteristic at the matching circuit, we obtained 3 times more amplitude at the electrodes. General shape of the spill is improved by this work, and extraction efficiency at a real operating condition is also improved.

WEOBPA01	First Results of the CRFQ Proof of Principle	rfq, proton, quadrupole, radio-frequency	1873
	D. Davino Universita' degli Studi del Sannio, Benevento L. Campajola Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli V. Lo Destro, A.G. Ruggiero BNL, Upton, Long Island, New York M.R. Masullo INFN-Napoli, Napoli V.G. Vaccaro Naples University Federico II and INFN, Napoli
	The Circular Radiofrequency Quadrupole is a new concept of a storage and accelerator ring for intense beams of light and heavy ions, protons and electrons. It is basically a Linear Radiofrequency Quadrupole completely bent on a circle. The advantages, which are expected to be the same performance features of a linear RFQ, would be smaller overall dimension with respect to accelerators with comparable beam intensity and emittance. A collaboration between BNL and Italian research institute and universities was set up at the end of 2002 with the aim of the proof of the bending principle. The prototype design is based on a 4-rods scheme and have a linear sector followed by a 45-degree curved sector. The 1mA proton beam, produced by a reconditioned RF source, go through a beam gap diameter of 10mm with circular 10mm diameters rods. Each sector is 700mm long and is placed in a 150mm diameter pipe*. The RF power at 202.56MHz is fed by a CERN "Frank James" 50kW amplifier. In this paper the first power and beam tests of the linear sector are presented. A.G. Ruggiero, C-A/AP/65 note, Brookhaven National Laboratory, October 2001. A.G. Ruggiero et al., Proceedings of the EPAC 2004 conference.*D. Davino et al., Proceedings of the EPAC 2004 conference.
	Transparencies

WEXFI01	Instabilities and Space Charge Effects in High Intensity Ring Accelerators	space-charge, damping, dipole, simulation	1882
	O. Boine-Frankenheim, I. Hofmann, V. Kornilov GSI, Darmstadt
	This presentation will review beam dynamics in circular accelerators with high beam intensity and space charge effects. The main focus will be on recent theoretical and experimental results related to collective instabilities and resonance crossing with space charge. In the first part of the presentation, the effect of space charge on collective instability thresholds and impedance budgets will be discussed. In this context the effect of space charge induced mode coupling on the longitudinal microwave instability will be illustrated. The stability of longitudinal bunched beam modes and of transverse dipole modes in the presence of space charge will be discussed. Recent work related to the transverse mode coupling instability (TMCI) with space charge will be reviewed. In the second part of the presentation, "incoherent" space charge effects on transverse nonlinear dynamics issues, like nonlinear resonance crossing, will be reviewed.
	Transparencies

WEPCH109	Comprehensive Benchmark of Electromagnetic 3D Codes in Time and Frequency Domain	simulation, damping, ESRF, vacuum	2167
	V. Serriere, N. Guillotin, J. Jacob ESRF, Grenoble F. Marhauser, E. Weihreter BESSY GmbH, Berlin
	A comprehensive benchmark of todays most powerful numerical 3D Eigenmode and Time Domain Solvers has been performed using the input geometry of a HOM-damped cavity and a highly lossy waveguide load developed at BESSY. The paper details the simulations results together with existing experimental data.

WEPCH110	Calculation of Wake Potentials in General 3D Structures	extraction, vacuum, radiation, controls	2170
	H. Henke TET, Berlin W. Bruns CERN, Geneva
	The wake potential is defined as an integration along an axis of a structure. It includes the infinitely long beam pipe regions and in case of numerical evaluation leads to pipe wake artefacts. If the structure is cavity like one can position the integration path on the pipe wall and only the integration over the cavity gap remains. In case of axis-symmetric protruding structures it was proposed by O. Napoly et al. to deform the path such that the integration in the pipe regions is again on the wall. The present paper generalizes this method of path deformation to 3D structures with incoming and outgoing beam pipes. Its usefulness is verified with the code GdfidL and no artifacts were observed.

WEPCH113	Numerical Impedance Calculations for the GSI SIS-100/300 Kickers	kicker, coupling, injection, simulation	2179
	B. Doliwa, H. De Gersem, T. Weiland TEMF, Darmstadt
	Fast kicker modules represent a potential source for beam instabilities in the planned Facility for Antiproton and Ion Research (FAIR) at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt. In particular, the more than fifty kicker modules to be installed in the SIS-100 and SIS-300 synchrotrons are expected to have a considerable parasitic influence on the high-current beam dynamics. Here we present our numerical investigations of the longitudinal and transverse kicker coupling impedances using a specialized electromagnetic field software. Besides the coupling to the external network, particular attention is paid to the question whether a resistively-coated ceramic beam pipe is able to reduce coupling impedances and ferrite heating significantly.

WEPCH115	Numerical Simulation and Optimization of a 3-GHz Chopper/Prebuncher System for the S-DALINAC	electron, simulation, MAMI, acceleration	2185
	N. Somjit, W.F.O. Müller, T. Weiland TEMF, Darmstadt R. Eichhorn, J. Enders, H.-D. Gräf, C. Heßler, Y. Poltoratska, A. Richter TU Darmstadt, Darmstadt
	A new source of polarized electrons with an energy of 100 keV is presently being developed at the superconducting Darmstadt electron linear accelerator S-DALINAC for future nuclear- and radiation-physics experiments. The pulsed electron beam emitted by the photocathode will be cut to 50 ps by a chopper operated at 3 GHz, and further bunch compression down to 5 ps will be achieved by a two-stage prebuncher section. The chopper-prebuncher system is based on similar devices used at the Mainz Mikrotron (MAMI) where the accelerator frequency is slightly smaller (2.4 GHz). For the chopper, a cylindrical resonator operating at TM110 mode is selected to deflect the electron beam onto an ellipse, i.e., both horizontally and vertically. This is simply achieved by particular slits on both ends of the resonator. The prebunching system consists of two cavities. For increasing the longitudinal capture efficiency, the first cavity will be operated at the fundamental accelerator frequency of the S-DALINAC of 3 GHz, and the second cavity at 6 GHz. The cavities are designed to work at the TM010 mode and TM020 mode for the fundamental and first harmonic, respectively.

WEPCH122	2D Wake Field Calculations of Tapered Structures with Different FDTD Discretization Schemes	vacuum, simulation, LEFT	2206
	C. Schmidt Rostock University, Institute for General Electrical Engn., Rostock H.-W. Glock, U. van Rienen Rostock University, Faculty of Engineering, Rostock
	The continual performance improvement of particle accelerators requires advanced prediction of parasitic wake field effects, even in structures of comparatively weak influence like tapers. In the case of smooth tapered components, even well established codes like MAFIA* demonstrate strong discretization dependency of the results or solver instabilities, making them not reliable in such applications. Grid dispersion is assumed to generate this failure. In Ref.** an alternative discretization scheme is described, using a homogeneous rotated mesh intended to eliminate such grid dispersion effects. In order to study the dependence on the discretization applied, we use this scheme to calculate wake fields in prototype taper structures of rotational symmetry. Furthermore a comparison is provided with the results of a non-rotated mesh, MAFIA runs and - so far applicable - analytical approaches. MAFIA V4.107: CST GmbH, Bad Nauheimer Str. 19, D-64289 Darmstadt*R. Hampel et al. New discretization scheme for wake field computation in cylindrically symmetric structure. Proc. EPAC'04, pp 2559

WEPCH164	High Power RF Tests of the First Module of the TOP Linac SCDTL Structure	linac, coupling, proton, booster	2313
	L. Picardi, C. Cianfarani, G. Messina, G.L. Orlandi, C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma) E. Cisbani, S.F. Frullani ISS, Rome
	The TOP Linac (Oncological Therapy with Protons), under development by ENEA and ISS, is a sequence of three pulsed (5 microseconds, 300 Hz) linear accelerators: a 7 MeV, 425 MHz RFQ+DTL (AccSys Model PL-7), a 7-65 MeV, 2998 MHz Side Coupled Drift Tube Linac (SCDTL), and a 65-200 MeV, variable energy 2998 MHz Side Coupled Linac (SCL). The first SCDTL module structure, composed by nine DTL tanks coupled by eight side cavities, has been built. Low power RF measurements have shown good field uniformity and stability along the axis. The structure has been tested with a 1 - 4 MW power RF. Results of low and high power tests are reported and discussed.

WEPLS039	Developments on a Diamond-based Cylindrical Dielectric Accelerating Structure	DIAMOND, electron, vacuum, simulation	2460
	A. Kanareykin, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio M.E. Conde, W. Gai, J.G. Power ANL, Argonne, Illinois P. Schoessow Tech-X, Boulder, Colorado
	Developments on a high gradient diamond-based cylindrical dielectric loaded accelerator (DLA) is presented. A diamond-loaded DLA can potentially sustain accelerating gradients far in excess of the limits experimentally observed for conventional metallic accelerating structures. The electrical and mechanical properties of diamond make it an ideal candidate material for use in dielectric accelerators: high RF breakdown level, extremely low dielectric losses and the highest available thermoconductive coefficient. We used the hot-filament Chemical Vapor Deposition (CVD) process to produce high quality 5-10 cm long cylindrical diamond layers. Our collaboration has also been developing a new method of CVD diamond surface preparation that reduces the secondary electron emission coefficient below unity. Special attention was paid to the numerical optimization of the coupling section, where the surface magnetic and electric fields were minimized relative to the accelerating gradient and within known metal surface breakdown limits.

WEPLS042	Design and Experimental Investigation of an X-band Multilayer Dielectric Accelerating Structure	simulation, vacuum, coupling, DESY	2466
	A. Kanareykin, C.-J. Jing, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio W. Gai, J.G. Power ANL, Argonne, Illinois
	A new project to significantly improve the efficiency of high gradient DLA structures is presented. A multilayer DLA where the single dielectric layer is replaced by a multiple coaxial layers of differing permittivity have been developed. The power attenuation in the multilayer structure is reduced by the Bragg Fiber principle where the dielectric layers are used to create multiple reflections in order to confine the accelerating mode fields for the most part in the dielectric, reducing the axial current on the conducting outer boundary. A design for an X-band multilayer structure operating in the TM03 mode using alternating dielectric layers with permittivities of 38 and 9.7 is discussed. In order to transfer the RF from the rectangular waveguide to the cylindrical one at TM03 mode, a special coupling and mode conversion scheme was developed. A prototype structure has been constructed and bench test results of the multilayer 11.424 GHz accelerator is presented.

WEPLS056	R&D Status of the High-intense Monochromatic Low-energy Muon Source: PRISM	simulation, lepton, synchrotron, focusing	2508
	A. Sato, M. Aoki, Y. Arimoto, I. Itahashi, Y. Kuno, K. Kuriyama, T. Oki, T. Takayanagi, M. Yoshida Osaka University, Osaka M. Aiba, C. Ohmori, T. Yokoi, K. Yoshimura KEK, Ibaraki Y. Iwashita Kyoto ICR, Uji, Kyoto S. Machida CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon Y. Mori KURRI, Osaka
	PRISM is a project of a future intense low-energy muon source, which combines monochromaticity and high purity. Its aimed intensity is about $10¹¹-10¹² muons per second. The muon beams will have a low kinetic energy of 20MeV so that it would be optimized for the stopped muon experiments such as searching the muon lepton flavor violating processes. PRISM consists of a pion capture section, a pion/muon transfer section and a phase rotation ssection. An FFAG is used as the phase rotator to achieve the monochromatic muon beams. This paper will describe design status of these sections as well as construction status of PRISM-FFAG.

WEPLS099	Fault Detection and Identification Methods Used for the LHC Cryomagnets and Related Cabling	LHC, diagnostics, cryogenics, superconducting-magnet	2607
	D. Bozzini, F. Caspers, V. Chareyre, Y. Duse, T. Kroyer, R. Lopez, A. Poncet, S. Russenschuck CERN, Geneva
	Several non-standard methods for electrical fault location have been successfully developed and tested. As part of the electrical quality assurance program, certain wires have to be subjected to a (high) DC voltage for the testing of the insulation. With the time difference of spark-induced electromagnetic signals measured with an oscilloscope, fault localization within a ± 10 cm range has been achieved. Another method used and adapted for the particular needs, was the synthetic pulse time-domain reflectometry (TDR) by means of a vector network analyzer. This instrument has also been applied as a low frequency sweep impedance analyzer in order to measure fractional capacities of cable assemblies where TDR was not applicable.

WEPLS115	Impedances in Slotted-Pipe Kicker Magnets	kicker, vacuum, storage-ring, simulation	2649
	F. Marhauser, O. Dressler, V. Duerr, J. Feikes BESSY GmbH, Berlin
	Storage ring slotted-pipe kicker magnets based on the DELTA design are foreseen for the Metrology Light Source (MLS) of the Physikalisch-Technische Bundesanstalt currently under construction near the BESSY site. Although the slotted pipe maintains the cross-section of the storage ring vacuum chamber, image currents have to bypass the slots generating wakefields. Actually modes with substantial impedances have been revealed by simulations and verified by measurements of a kicker model for the MLS.

WEPLS134	Design and Modeling of the Step Down Piezo Transformer	controls, simulation, power-supply, feedback	2691
	C.-Y. Liu, Y.-C. Chien, K.-B. Liu NSRRC, Hsinchu
	The energy conversion and the step down voltage waveform of the piezo transformer are required to achieve optimal working condition of the resonate frequency. To meet this requirement, a reliable and precise instrument is needed to scan the resonated point of the piezo transformer such that the piezo transformer's output performance can meet required specification. In this paper, design and modeling of a new step down piezo transformer deployed in NSRRC is described. This step down piezo transformer is capable of delivering energy conversion with high efficiency performance, which is better than traditional transformer, and the voltage transfer ratio is correct. The simulation circuit model used to develop driver circuit of the piezo transformer is also included in the design of this new step down transformer. It has been tested and proven to be working well in power conversion with excellent efficiency and reliability.

THPCH031	Impedance and Beam Stability Study at the Australian Synchrotron	synchrotron, storage-ring, higher-order-mode, resonance	2844
	R.T. Dowd, M.J. Boland, G. LeBlanc, M.J. Spencer, Y.E. Tan ASP, Clayton, Victoria
	We present the preliminary results of an impedance study of the Australian Synchrotron storage ring. Beam stability thresholds have been determined and an overall impedance budget set. Broad-band impedance has been evaluted for various components of the vacuum chamber, using both analytical formulae and results from MAFIA simulations. Narrow band resonances have also been investigated, with particular attention paid to higher order modes in the RF cavities and their effect on multi-bunch instabilities.

THPCH032	Instability Studies Using Evaluated Wake Fields and Comparison with Observations at SOLEIL	SOLEIL, single-bunch, simulation, betatron	2847
	R. Nagaoka SOLEIL, Gif-sur-Yvette
	Beam instability is predicted for SOLEIL using the impedance data obtained through component-wise numerical evaluations. The paper also attempts to make the first comparison with measurements. A key issue for SOLEIL has been to acquire precise knowledge of impedance up to a few tens of GHz, due to short bunches, of chambers which are essentially 3D and additionally NEG coated to a large part, which is expected to enhance the reactive part of the resistive-wall impedance. The predictability of instabilities with the data attained thus becomes a large concern. Wake potentials computed with a 3D code are transformed to impedances and decomposed into a series of resonators, inductive and resistive components, to deduce the wake functions, while for NEG coated chambers, they are numerically Fourier transformed from analytically derived impedances. Both time and frequency domain simulations are performed to predict the longitudinal and transverse instabilities in single bunch, as well as resistive-wall instabilities in multibunch as a function of chromaticity. A multibunch tracking is also performed to investigate the filling pattern dependence of the latter.

THPCH033	Recent Studies of Geometric and Resistive-wall Impedance at SOLEIL	SOLEIL, LEFT, vacuum, single-bunch	2850
	R. Nagaoka, J.-C. Denard, M.-P. Level SOLEIL, Gif-sur-Yvette
	Coupling impedance studies are of great importance for SOLEIL not only to avoid beam instability, but also to ensure protection of a concerned chamber from EM fields excited by the beam. This paper deals with components that required particularly such efforts, which include BPMs, ceramic chambers, and a vertical scraper. The heat deposited in the BPM buttons is investigated as a function of the gap between a button and an electrode, button diameter and thickness. High temperatures on a vacuum tight feed-through would be a problem, affecting the measurement stability at high currents. Coupling of a trapped mode among successively passing bunches is also investigated. To evaluate the heat deposited in a titanium coated ceramic chamber, its impedance is analytically solved using the field matching technique. The solution obtained justifies the image current model that assumes a constant image current density across the coating when the skin depth is greater than the coating thickness. The azimuthal image current distribution is pursued with Piwinski's formalism for flat chambers. The paper also deals with components not treated earlier such as a stripline.

THPCH034	Transverse Coupling Impedances From Field Matching in a Smooth Resistive Cylindrical Pipe for Arbitrary Beam Energies	coupling, LHC, SIS, CERN	2853
	A.M. Al-Khateeb, A.M. Al-Khateeb, W.M. Daqa Yarmouk, Irbid O. Boine-Frankenheim, R.W. Hasse, I. Hofmann GSI, Darmstadt
	The transverse coupling impedance is investigated analytically. For an off-axis motion of the beam, the perturbed charge distribution of the beam becomes a function of the azimuthal angle, resulting to first order in the beam displacement in a dipole term which is the source of the transverse impedance. All six components of the electromagnetic field are different from zero and, therefore, both TM and TE modes will be excited in the beam-pipe and coupled to the beam at the inner surface of the resistive wall. Using the dipole source term, a linear combination of TM and TE modes is used to get closed form expressions for the transverse electromagnetic field components excited in the beam-pipe, and a generalized analytic expression for the corresponding transverse coupling impedance. It has been found that the contributions of the TM and the TE modes to the real part of the transverse resistive-wall impedance have similar dependence on the relativistic parameter but with opposite signs, the sum of both always being positive. Some approximate simple formulas for three important regions corresponding to small, intermediate and large frequencies in the ultrarelativistic limit were also obtained analytically.

THPCH035	Characterisation of the EU-HOM-damped Normal Conducting 500 MHz Cavity from the Beam Power Spectrum at DELTA	CBM, synchrotron, single-bunch, storage-ring	2856
	R.G. Heine, P. Hartmann, T. Weis DELTA, Dortmund
	A HOM-damped prototype cavity developed in the framework of an EC collaboration has been installed into the Dortmund synchrotron light source DELTA. This paper reports on beam studies performed at beam energies of 1.5 GeV and 542 MeV in an attempt to get information on coupled bunch instability thresholds. In addition an evaluation of the longitudinal cavity impedance is presented, based on beam power spectra up to 3 GHz for different filling patterns of the storage ring by analysing the RF signal from the HOM-dampers.

THPCH036	Wakefield Calculations for 3D Collimators	SLAC, simulation, LEFT, DESY	2859
	I. Zagorodnov DESY, Hamburg K.L.F. Bane SLAC, Menlo Park, California
	The wakefield effects of the collimators is of concern for future projects. To relax the wakefield effects a gradual transition from a large to a small aperture is used. The impedance of a smooth round collimator is understood well and a good agreement between measurements, theory and simulations is achieved. However, for rectangular flat collimators there is noticeable difference between theory and experiment. Using recently developed time domain numerical approach, which is able to model curved boundaries and does not suffer from dispersion in longitudinal direction, we calculate the short-range geometric wakefields of 3D collimators. This method together with developed by us recently indirect 3D integration algorithm allows to obtain accurate numerical estimations, which are compared to measurements and to analytical results. The applicability range for the analytical formulas is highlighted.

THPCH038	The PANDA Insertion Impedance in High Energy Storage Ring of FAIR	insertion, CERN, vacuum, storage-ring	2865
	E. Senicheva, A. Lehrach, D. Prasuhn FZJ, Jülich
	The PANDA insertion due to the special shape of the vacuum pipe creates a discontinuity. This was expected to be the main contribution in the impedance of the vacuum chamber. In this paper we present the results of computations dealing with this problem. From many published articles it is known that the reliability of the results depends on many factors and some time they differ from each other significantly. Therefore we have investigated the impedance of the PANDA insertion using different codes and methods, in particular, MAFIA, ABCI and the analytical estimation with the formula Yakoya recognized as a most successful theoretical estimation of the tapers. Besides, PANDA has two symmetrical T-shape insertions, which have been calculated by 3D MAFIA and compared with the results given by the diffraction theory. We have analysed the longitudinal and the transverse impedance.

THPCH042	Numerical Estimations of Wakefields and Impedances for Diamond Collimators	simulation, DIAMOND, storage-ring, injection	2877
	S.A. Pande, R. Bartolini, R. T. Fielder, M. Jensen Diamond, Oxfordshire
	The storage ring of the Diamond light source will use two collimators, one in horizontal and one in the vertical planes in the injection straight to protect the IDs from the injection and Touschek losses. These collimators, in the form of tapered metallic intrusions in to the vacuum chamber, will generate considerable wake fields and will contribute to the overall machine impedance. In this paper we present the results of ABCI and MAFIA numerical simulations to estimate these effects.

THPCH045	Transverse Head-tail Modes Elimination with Negative Chromaticity and the Transverse Multi-bunch Feedback System at ELETTRA	feedback, ELETTRA, coupling, kicker	2886
	E. Karantzoulis, M. Lonza ELETTRA, Basovizza, Trieste
	The rigid dipole head-tail mode threshold at ELETTRA is by now quite low and increasing positively the chromaticity does not bring a much overall advantage in the machine performance. Using the bunch-by-bunch transverse feedback (TMFB), a threshold increase has been observed until the onset of the higher modes, which being bunch shape modes cannot be detected and therefore eliminated by the feedback system. To overcome this problem the machine has been set to a small but negative chromaticity. In this case the m=0 mode is unstable with a very low (<1 mA/bunch) threshold but the higher modes should be stable, especially when the main source of the transverse impedance comes from the resistive wall as in our case. Indeed when activating the TMFB no onset of any modes was observed within reasonable current limits (15 mA/bunch) that we plan to further investigate. In the paper after a theoretical discussion on the role of chromaticity and various types of impedances in the head-tail onset mechanism, the experimental results are presented and discussed.

THPCH054	SIMPSONS with Wake Field Effects	kicker, extraction, injection, emittance	2910
	Y. Shobuda, F. Noda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken Y.H. Chin, K. Takata, T. Toyama KEK, Ibaraki S. Machida CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
	Simpsons, which is originally developed by S. Machida, is the program which calculates the space charge effect to the beam in the ring. The wake field effect to the beam is also installed in this program, because the emittance growth not only due to the space charge effect, but also due to the wake field effect is the important issue. The results of the simulation in J-PARC case are also represented.

THPCH057	The Fast Vertical Single-bunch Instability after Injection into the CERN Super Proton Synchrotron	SPS, simulation, emittance, LHC	2913
	E. Métral, G. Arduini, T. Bohl, H. Burkhardt, G. Rumolo CERN, Geneva B. Spataro INFN/LNF, Frascati (Roma)
	Since 2003, high-intensity single-bunch proton beams with low longitudinal emittance have been affected by heavy losses after less than one synchrotron period after injection. The effects of the resonance frequency of the responsible impedance, longitudinal emittance and chromaticity on the intensity threshold were already discussed in detail in 2004, comparing analytical predictions with simulation results. In this paper the evolution of the instability between injection and the time of beam loss is our main concern. Measurements are compared with HEADTAIL simulations. A travelling-wave pattern propagating along the bunch, which is the signature of a Beam Break-Up or Transverse Mode Coupling Instability (TMCI), is clearly identified. The oscillating frequency, near ~1 GHz, is in good agreement with the usual broad-band impedance model deduced from beam-based measurements like the head-tail growth rate vs. chromaticity.

THPCH058	Simulation Study on the Beneficial Effect of Linear Coupling for the Transverse Mode Coupling Instability in the CERN Super Proton Synchrotron	coupling, SPS, simulation, CERN	2916
	E. Métral, G. Rumolo CERN, Geneva
	The intensity threshold of the transverse mode coupling instability in a flat vertical chamber, as in the CERN Super Proton Synchrotron, is much higher in the horizontal plane than in the vertical one. This asymmetry between the transverse planes led us to the idea that linear coupling from skew quadrupoles could be used to increase the intensity threshold. This technique is already applied, for instance, in the CERN Proton Synchrotron, where a slow head-tail horizontal instability due to the resistive-wall impedance is stabilized by linear coupling only, i.e. with neither octupoles nor feedbacks. This paper presents the results of the study of the effect of linear coupling on the transverse mode coupling instability, using the HEADTAIL simulation code.

THPCH059	Kicker Impedance Measurements for the Future Multi-turn Extraction of the CERN Proton Synchrotron	kicker, extraction, LEFT, resonance	2919
	E. Métral, F. Caspers, M. Giovannozzi, A. Grudiev, T. Kroyer, L. Sermeus CERN, Geneva
	In the context of the novel multi-turn extraction, where charged particles are trapped into stable islands in transverse phase space, the ejection of five beamlets will be performed by means of a set of three new kickers. Before installing them into the machine, a measurement campaign has been launched to evaluate the impedance of such devices. Two measurement techniques were used to try to disentangle the driving and detuning impedances. The first consists in measuring the longitudinal impedance for different transverse offsets using a single displaced wire. The sum of the transverse driving and detuning impedances is then deduced applying Panofsky-Wenzel theorem. The second uses two wires excited in opposite phase and yields the driving transverse impedance only. Finally, the consequences on the beam dynamics are also analyzed.

THPCH060	Simulation Study on the Energy Dependence of the TMCI Threshold in the CERN-SPS	electron, simulation, SPS, space-charge	2922
	G. Rumolo, E. Métral, E.N. Shaposhnikova CERN, Geneva
	This paper concentrates on theoretical studies of Transverse Mode Coupling Instability at the SPS. It shows the expected thresholds based on a HEADTAIL tracking model and on impedance values estimated from previous measurements. First, the effect of space charge is addressed as an important ingredient at the low energies. Subsequently, the change of TMCI threshold possibly induced by a higher injection energy into the SPS (plausible according to the upgrade studies) is investigated and a scaling law with energy is derived.

THPCH061	Tune Shift Induced by Nonlinear Resistive Wall Wake Field of Flat Collimator	emittance, SPS, CERN, LHC	2925
	F. Zimmermann, G. Arduini, R.W. Assmann, H. Burkhardt, F. Caspers, M. Gasior, O.R. Jones, T. Kroyer, E. Métral, S. Redaelli, G. Robert-Demolaize, F. Roncarolo, G. Rumolo, R.J. Steinhagen, J. Wenninger CERN, Geneva
	We present formulae for the coherent and incoherent tune shifts due to the nonlinear resistive wall wake field for a single beam traveling between two parallel plates. In particular, we demonstrate that the nonlinear terms of the resistive wall wake field become important if the gap between the plates is comparable to the transverse rms beam size. We also compare the theoretically predicted tune shift as a function of gap size with measurements for an LHC prototype graphite collimator in the CERN SPS and with simulations.

THPCH062	Collective Effects in the Storage Ring of Taiwan Photon Source	storage-ring, insertion, insertion-device, damping	2928
	P.J. Chou, C.H. Kuo, C.-C. Kuo, M.-H. Wang NSRRC, Hsinchu
	A new 3- 3.3 GeV synchrotron light source is proposed and named the Taiwan Photon Source (TPS). The TPS design has a natural horizontal emittance less than 2 nm-rad and low emittance coupling, which results in small beam size. The nominal bunch length in TPS storage ring is much shorter compared to the existing Taiwan Light Source, that makes the issue of parasitic heating more significant. Several small-gap insertion devices are planned to provide extremely bright x-ray photon beam. Those design features have impacts on collective beam instabilities. A preliminary study of collective effects in the TPS storage ring is presented.

THPCH065	Suppression of Transverse Instability by a Digital Damper	damping, kicker, space-charge, antiproton	2934
	A.V. Burov, V.A. Lebedev Fermilab, Batavia, Illinois
	When a beam phase space density increases, it makes its motion intrinsically unstable. To suppress the instabilities, dampers are required. With a progress of digital technology, digital dampers are getting to be more and more preferable, compared with analog ones. Conversion of an analog signal into digital one is described by a linear operator with explicit time dependence. Thus, the analog-digital converter (ADC) does not preserve a signal frequency. Instead, a monochromatic input signal is transformed into a mixture of all possible frequencies, combining the input one with multiples of the sampling frequency. Stability analysis has to include a cross-talk between all these combined frequencies. In this paper, we are analyzing a problem of stability for beam transverse microwave oscillations in a presence of digital damper; the impedance and the space charge are taken into account. The developed formalism is applied for antiproton beam in the Recycler Ring at Fermilab.

THPCH069	BBU Calculations for Beam Stability Experiments on DARHT-2	BBU, simulation, induction, electron	2943
	Y. Tang ATK-MR, Albuquerque, New Mexico K.C.D. Chan, C. Ekdahl LANL, Los Alamos, New Mexico T.P. Hughes Voss Scientific, Albuquerque, New Mexico
	The DARHT-2 (Dual-Axis Radiographic Hydrodynamics Test) facility is expected to produce a 2-kA, 20-MeV, 2-microsecond flattop electron beam pulse. Normal operation requires that the beam exit the accelerator with a normalized transverse emittance of less than 0.15-cm-rad. The beam break up (BBU) instability is a potentially serious effect for a high current linear accelerator. It arises from the interaction between the beam and the cavity modes of the accelerating cells. In support of the beam stability experiments, simulations of BBU for DARHT-2 using the Lamda code have been carried out. The simulations used experimental data for the transverse impedance of the cells. Lamda was benchmarked against results calculated with the LLNL code BREAKUP. For nominal transport parameters, simulation results showed that the BBU growth was not significant in changing the beam spot. For a magnetic field reduced by a factor of 5, BBU growth was over a factor of 100, and the image displacement effect was significant.

THPCH070	Long-pulse Beam Stability in the DARHT-II Linear-induction Accelerator	BBU, ion, vacuum, induction	2946
	C. Ekdahl, E.O. Abeyta, P.A. Aragon, R. Archuleta, R. Bartsch, K.C.D. Chan, D. Dalmas, S. Eversole, R.J. Gallegos, J. Harrison, E. Jacquez, J. Johnson, B.T. McCuistian, N. Montoya, S. Nath, D. Oro, L.J. Rowton, M. Sanchez, R.D. Scarpetti, M. Schauer LANL, Los Alamos, New Mexico H. Bender, W. Broste, C. Carlson, D. Frayer, D. Johnson, A. Tipton, C.-Y. Tom Bechtel Nevada, Los Alamos, New Mexico R.J. Briggs SAIC, Alamo, California T.P. Hughes, C. Mostrom, Y. Tang ATK-MR, Albuquerque, New Mexico M.E. Schulze GA, San Diego, California
	The beam breakup instability has long been a problem for linear induction accelerators (LIAs). Although it is predicted to saturate in the strong focus regime relevant to LIAs most, if not all, LIAs have had pulse-widths too short to observe this effect. We recently completed BBU experiments on a 1.2 kA, 6.7-MeV configuration of the DARHT-II LIA having a 1600-ns pulse length much longer than the saturation time. The saturated growth observed in these experiments when we reduced the magnetic guide-field strength was in agreement with theory. We used these results to deduce that BBU growth will be insignificant in the final 2-kA, 17-MeV DARHT-II configuration with the tunes that will be used. Another problematic instability for long-pulse LIAs such as DARHT-II is the ion-hose. We also performed experiments with the 6.7-MeV long-pulse configuration of DARHT-II in which we deliberately induced ion-hose by raising the background pressure far above its normal value. The results of these experiments were used to show that ion-hose will not be a problem for to the final DARHT-II configuration.

THPCH071	Coupling Impedances of Small Discontinuities for Non-ultrarelativistic Beams	dipole, coupling, vacuum, LANL	2949
	S.S. Kurennoy LANL, Los Alamos, New Mexico
	The beam coupling impedances of small discontinuities of an accelerator vacuum chamber have been calculated (e.g., * and references therein) for ultrarelativistic beams using Bethe's diffraction theory. Here we extend the results for an arbitrary beam velocity. The vacuum chamber is assumed to have an arbitrary, but fixed, cross section. The longitudinal and transverse coupling impedances are derived in terms of series over cross-section eigenfunctions, while the discontinuity shape enters via its polarizabilities. Simple explicit formulas for the circular and rectangular cross sections are presented. The impedance dependence on the beam velocity exhibits some unusual features. For example, the reactive impedance, which dominates in the ultrarelativistic limit, can vanish at a certain beam velocity, or its magnitude can exceed the ultrarelativistic value many times. *S. S. Kurennoy et al. Phys. Rev. ·10⁵² (1995) 4354.

THPCH073	Reflectivity Measurements for Copper and Aluminum in the Far Infrared and the Resistive Wall Impedance in the LCLS Undulator	LCLS, undulator, SLAC, FEL	2955
	K.L.F. Bane, G.V. Stupakov SLAC, Menlo Park, California J. Tu City College of The City University of New York, New York
	Reflectivity measurements in the far infrared, performed on aluminum and copper samples, are presented and analyzed. Over a frequency range of interest for the LCLS bunch, the data is fit to the free-electron model, and to one including the anomalous skin effect. The models fit well, yielding parameters dc conductivity and relaxation times that are within 30-40\% of expected values. We show that the induced energy in the LCLS undulator region is relative insensitive to variations on this order, and thus we can have confidence that the wake effect will be close to what is expected.

THPCH076	Resistive Wall Wake Effect of a Grooved Vacuum Chamber	vacuum, SLAC, electron, positron	2961
	G.V. Stupakov, K.L.F. Bane SLAC, Menlo Park, California
	To suppress the emission of secondary electrons in accelerators with positively charged beams (ions or positrons) it has been proposed to use a vacuum chamber that is longitudinally grooved (or, equivalently, one can say finned)/. One consequence of having such a chamber in an accelerator is an increased resistive wall impedance. In this paper, we calculate the resistive wall impedance of one such finned chamber, planned to be used in experimental studies of secondary emission suppression at SLAC. For rectangular fins, we use an analytical method based on a conformal mapping approach; we compare the results with a numerical solution of the field equation. We also numerically compute the impedance for rounded fins (as will be used in the SLAC experiment) and analyse how the impedance depends on geometric properties of the fins. A. A. Krasnov. Vaccum, vol. 73, p. 195, (2004).**G. Stupakov and M. Pivi. Preprint SLAC-TN-04-045, (2004).

THPCH077	Resistive-wall Instability in the Damping Rings of the ILC	feedback, damping, vacuum, betatron	2964
	L. Wang, K.L.F. Bane, T.O. Raubenheimer, M.C. Ross SLAC, Menlo Park, California
	In the damping rings of the International Linear Collider (ILC), the resistive-wall instability is one of the dominant transverse instabilities. This instability directly influences the choice of material and aperture of the vacuum pipe, and the parameters of the transverse feedback system. This paper investigates the resistive-wall instabilities in an ILC damping ring under various conditions of beam pipe material, aperture, and fill pattern.

THPCH080	Transverse Impedance of Small-gap Undulators for NSLS-II	undulator, vacuum, permanent-magnet, electron	2970
	A. Blednykh, S. Krinsky, B. Podobedov, J.-M. Wang BNL, Upton, Long Island, New York
	We discuss the transverse impedance resulting from the use of small-gap undulators in the proposed NSLS-II storage ring. For superconducting undulators, the impedance arises due to the tapered elliptical vacuum chamber. For in-vacuum permanent magnet devices, the impedance results from a more complex geometry. We consider both cases and report results obtained using the electromagnetic simulation program GdfidL.

THPCH081	Transverse Impedance of Elliptical Cross-section Tapers	vacuum, BNL, damping, synchrotron	2973
	B. Podobedov, S. Krinsky BNL, Upton, Long Island, New York
	We investigate the transverse impedance of elliptical cross-section tapers. Analytical estimates for the dipole and quadrupolar components of the impedance at low frequency are obtained by extending a perturbation approach introduced by Stupakov. The perturbation theory results are compared to EM code GdfidL and are found to be in excellent agreement.

THPCH087	Design and Operation of a Ferrite Loaded Kicker Cavity for the Longitudinal Coupled Bunch Feedback for HERA-p	resonance, kicker, damping, feedback	2991
	J. Randhahn, S. Choroba, M. Dohlus, M. Ebert, F.E. Eints, M.G. Hoffmann, R. Wagner DESY, Hamburg
	A longitudinal broadband damper system to control coupled bunch instabilities has recently been constructed and installed in the 920 GeV proton accelereator HERA-p at the Deutsches Elektronen-Synchrotron DESY. The goal of this system is to reduce the bunch length and thus increase specific luminosity at HERA-p. Within the control system a kicker cavity is used as an actuator. The original aspect of this cavity lies in the simple geometry with no need for vacuum inside the cavity and high shunt impedance despite an internal ferrite load. The ferrite load is succesfully used to dampen higher order modes down to Q < 50 while the fundamental mode is damped by less than 2 dB. While nominal input power is rated at 60 dBm the cavity is prepared to handle beam loading. In spite of power requirements and ferrite load the cavity needs no active cooling. It can be tuned in center frequency and bandwidth over a range of 96..105 MHz and 4..7 MHz respectively and in consequence provides an optimal actuator for the particle beam control system. Presented will be the design details, all relevant parameters, the design of the internal ferrite load and operational experience.

THPCH093	Bunch-by-bunch Feedback for the Photon Factory Storage Ring	feedback, damping, kicker, controls	3009
	W.X. Cheng, T. Honda, M. Izawa, T. Obina, M.T. Tadano, M. Tobiyama KEK, Ibaraki K. Kobayashi, T. Nakamura JASRI/SPring-8, Hyogo-ken
	After the straight-section upgrade in 2005, the PF (Photon Factory) ring will start the top-up operation or the continuous mode in 2006. Previously the octupole magnets were used to suppress the transverse coupled bunch instability and RF modulation method to enhance the bunch length has been effectively used to suppress the longitudinal instabilities. However, such kind of methods are not suitable for the top-up operation, we are preparing active bunch-by-bunch feedback systems for both transverse and longitudinal plane. The transverse feedback system has been installed along with the straight-section upgrade, this system uses a FPGA based feedback processor board developed at the SPring-8, both horizontal and vertical signals are processed in a single control loop. For the longitudinal feedback, a two-port DAFNE type wide-band cavity has been designed and is now manufacturing, a digital signal processing part is under design, the whole system will start commissioning in autumn 2006.

THPCH098	FPGA-based Longitudinal Bunch-by-bunch Feedback System for TLS	feedback, kicker, FIR, synchrotron	3023
	C.H. Kuo, J. Chen, P.J. Chou, K.-T. Hsu, S.Y. Hsu, K.H. Hu, W.K. Lau, D. Lee, C.-J. Wang, M.-H. Wang, M.-S. Yeh NSRRC, Hsinchu M. Dehler PSI, Villigen K. Kobayashi, T. Nakamura JASRI/SPring-8, Hyogo-ken
	A FPGA Based Longitudinal Bunch-by-Bunch Feedback System for TLS is commissioning recently to suppress strong longitudinal oscillation. The system consists of pickup, Bunch oscillation detector, FPGA based feedback processor borrow form the design of Spring8. Modulator converts the correction signal to the carrier frequency and longitudinal kicker which was re-designed form SLS' and working at 1374 MHz. The feedback processor is based upon latest generation FPGA feedback processor to process bunch signals. The memory capture is up to 250 msec bunch oscillation signal. The software and hardware design are also included for system diagnostic and support various beam physics study. Preliminary commission result will be summaried in this report.

THPCH101	Modeling and Simulation of Longitudinal Dynamics for LER-HER PEP II Rings	simulation, feedback, klystron, controls	3032
	C.H. Rivetta, J.D. Fox, T. Mastorides, D. Teytelman, D. Van Winkle SLAC, Menlo Park, California
	A time domain dynamic model and simulation tool for beam-cavity interactions in LER and HER rings at PEP II is presented. The motivation for this tool is to explore the stability margins and performance limits of PEP II LLRF systems at higher currents and upgraded RF configurations. It also serves as test bed for new control algorithms and to define the ultimate limits of the architecture. The tool captures the dynamical behavior of the beam-cavity interaction based on a reduced model. It includes nonlinear elements in the klystron and signal processing. The beam current is represented by macro-bunches. Multiple RF stations in the ring are represented via one or two single macro-cavities. Each macro-cavity captures the overall behavior of all the 2 or 4 cavity RF stations. This allows modeling the longitudinal impedance control loops interacting with the longitudinal beam model. Validation of simulation tool is in progress by comparing the measured growth rates for both LER and HER rings with simulation results. The simulated behavior of both machines at high currents are presented comparing different control strategies and the effect of non-linear klystrons and the linearizer.

THPCH120	Development of a General Purpose Power System Control Board	controls, diagnostics, SLAC, induction	3083
	S.H. Nam, S.-H. Jeong, S.H. Kim, S.-C. Kim, S.S. Park, J.-H. Suh PAL, Pohang, Kyungbuk P. Bellomo, R. Cassel, R. Larsen, M.N. Nguyen SLAC, Menlo Park, California
	As high frequency switching solid state devices are replacing tube devices and linear devices, power systems become more compact and modular. In those systems, it is desirable to have a high quality and multi-function control board per each power system module. In order to maintain reliable operation of the power system module, the control board requires having multiple and complex functions. Moreover, the control board needs to be compact and low power consuming. It also needs to have a fast communication with the main control station. However, there is no such control board available commercially. Therefore, a general purpose power system control board (PSCB) has been under development since 2005 as a collaboration effort between PAL and SLAC. The PSCB is an embedded, interlock supervisory, diagnostic, timing, and set-point control board. It is designed to use in various power systems such as sequenced kicker pulsers, solid state RF modulators, simple DC magnet power supplies, etc. The PSCB has the Ethernet communication with the TCP/IP Modbus protocol. This paper will describe detail functions and preliminary test results of the PSCB.

THPCH130	Design and Implementation of Analog Feedback Damper System for an Electron-proton Instability at the Los Alamos Proton Storage Ring	feedback, kicker, storage-ring, LEFT	3104
	C. Deibele, S. Assadi, V.V. Danilov, S. Henderson, M.A. Plum, C. Sibley III ORNL, Oak Ridge, Tennessee S. Breitzmann, S.-Y. Lee IUCF, Bloomington, Indiana J.M. Byrd LBNL, Berkeley, California J.D. Gilpatrick, R.J. Macek, R.C. McCrady, J.F. Power, J. Zaugg LANL, Los Alamos, New Mexico
	The PSR (Proton Storage Ring) at LANSCE has observed an E-P (electron-proton) instability. A wideband analog feedback damper system was designed and implemented that has shown it is possible to correct this instability. The damper system consists of two 180 degree hybrids, low level amplifiers, a delay line, comb filter, power amplifiers, and adjustable delay lines. The system bandwidth is about between 10^-300 MHz, and was developed and implemented in stages showing improvement in the e-p threshold of the buncher voltage. The system takes advantage of fiber optic technology for delays as well as for the comb filter. A system description and some measurement results are presented.

THPCH140	New Pulsed Current and Voltage Circuits Based on Transmission Lines	SLS, coupling, laser	3122
	V. Nassisi, F. Belloni, D. Doria, A. Lorusso, M.V. Siciliano, L. Velardi INFN-Lecce, Lecce
	We present two novel circuits able to compress current or voltage pulse named current compressor circuit (CCC) and voltage compressor circuit (VCC), and two novel amplifier circuits able to double the current or voltage pulse. The compressing circuits were composed by a transmission line, l long and a storage line, l/2 long. The CCC compressed the current pulse by a factor of 2 doubling its intensity, while the VCC compressed the voltage pulse by a factor of 2 doubling its amplitude. The amplifying circuits were composed by a R0 transmission line closed on a set of two parallel or series storage lines which doubled the intensity of the pulses. The current pulse amplifier (CPA) had two R0/2 storage lines in parallel, while the voltage pulse amplifier (VPA) had two 2R0 storage lines in series. The storage line was half long with respect to the input-pulse. In both circuits, one storage line was characterized by an open extremity and the other line by a closed extremity. Connecting the storage lines to suitable load resistors, R0/4, and 4R0 for the CPA and VPA, respectively, a twice of the pulse intensity was obtained. The circuits were studied by computer simulations.

THPCH143	The Fast Extraction Kicker System in SPS LSS6	kicker, SPS, extraction, LHC	3125
	E.H.R. Gaxiola, F. Caspers, L. Ducimetière, P. Faure, T. Kroyer, B. Versolatto, E. Vossenberg CERN, Geneva
	A new fast extraction has been set up in SPS LSS6 to transfer 450 GeV/c protons as well as ions to Ring 1 of the LHC, via the transfer line TI 2. The system includes four travelling wave kicker magnets, recuperated from earlier installations and upgraded to fit the new application. All four magnets are powered in series, energised by a single PFN generator and terminated by a short circuit. The layout and the modifications to the magnets and the high voltage circuit are described along with the impact of design choices on the performance of the system. Results from laboratory tests and first machine experience are reported on approaches to overcome the effects of the beam induced kicker heating observed earlier, including a beam screen in form of metallic stripes printed directly onto the ferrites and the use of ferrite blocks with high Curie temperature. Prospects for further improvements are briefly discussed.

THPLS076	Status of RF Deflecting Cavity Design for the Generation of Short X-Ray Pulses in the Advanced Photon Source Storage Ring	damping, radiation, storage-ring, KEK	3460
	G.J. Waldschmidt, M. Borland, Y.-C. Chae, K.C. Harkay, D. Horan, A. Nassiri ANL, Argonne, Illinois
	The Advanced Photon Source (APS) at Argonne National Laboratory is exploring the possibility of using radio frequency deflection to generate x-ray radiation pulses on the order of 1 pico-second (Delta t - 70%) or less. This scheme is based on a proposal by A. Zholents et al.* that relies on manipulating the transverse momenta of the electrons in a bunch by using an rf deflecting cavity to induce a longitudinally dependent vertical deflection of the beam. The beam will then travel through a number of undulators before arriving at a second set of deflecting cavities where the deflection is reversed such that the remainder of the storage ring is largely unperturbed**. Considerable effort has been expended on the design of a superconducting rf deflecting cavity operating in the S-Band at 2.8 GHz to address fundamental design issues including cavity geometry, deflecting voltage, rf power coupling, tuning, and damping of higher-order and lower-order modes. In this paper we present simulation results and analysis of an optimized superconducting rf deflecting cavity design for the APS storage ring. K. Harkay et al. Proceedings of 2005 PAC, Knoxville, TN, May 2005, p. 668. A. Zholents et al. Nucl. Instrum. Methods, A425, 385 (1999). *M. Borland and V. Sajaev. Proceedings of 2005 PAC, Knoxville, TN, May 2005, p. 3886.

THPLS113	Design of a Fast Extraction Kicker for the Accelerator Test Facility	kicker, extraction, damping, SLAC	3544
	S. De Santis, A. Wolski LBNL, Berkeley, California M.C. Ross SLAC, Menlo Park, California
	We present a study for the design of a fast extraction kicker to be installed in the Advanced Test Facility ring. The purpose of the project is to test the technologies to be used in the design of the extraction kickers for the ILC damping rings. The kicker's rise and fall times are important parameters in the design of the damping rings, as they limit the minimum distance between bunches and ultimately define a lower boundary for the ring length. We propose a stripline kicker composed of several 20-cm long sections, grouped in two locations in the ATF damping ring. An analytical study of the kicker's parameters and computer simulations using Microwave Studio* point out the strict requirements on the pulsers, in order to be able to satisfy the design parameters. *http://www.cst.com