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Paper	Title	Other Keywords	Page
MOYBPA02	Operation of High-luminosity Meson Factories and the Challenge to go to the Next Generation	luminosity, factory, KEKB, electron	19
	K. Akai KEK, Ibaraki
	This talk will present an overview of the operational status of B- and Phi-Factories, and address their present luminosity performance and limitations, such as electron cloud effects. It will also discuss upgrade plans, including motivation and beam dynamics challenges, new ideas, R&D and machine experiments in view of the next generation of meson factories with ~100 times more luminosity. In particular, it will address machine tests with strong RF focusing, crab cavity developments and first operational experience at KEKB.
	Transparencies

MOPCH140	Compensation of Lorentz Force Detuning of a TTF 9-cell Cavity with a New Integrated Piezo Tuner	TTF, klystron, controls, resonance	378
	G. Devanz, P. Bosland, M. Desmons, E. Jacques, M. Luong, B. Visentin CEA, Gif-sur-Yvette
	The high gradient operation of superconducting elliptical multicells in pulsed mode is required for linear colliders or free-electron lasers based on the superconducting technology. Such an operation is limited by dynamic Lorentz force detuning if no compensation for this effect is attempted. The RF power headroom required for accelerating field amplitude and phase stabilisation by low-level RF control techniques solely would be too costly. A new active tuner with integrated piezo actuators has been developped in the framework of the european CARE/SRF program solve this issue. The design is based on the lever-arm concept of the Saclay tuner already installed on running TTF cavities. We have carried out integrated tests of the 9-cell cavity equipped with the piezo tuner and power coupler in the CryHoLab horizontal test cryostat. Characterisation of the electromechanical system consisting of the cavity and piezo-tuner assembly and full power pulsed tests will be presented.

MOPCH181	1.3 GHz Electrically-controlled Fast Ferroelectric Tuner	coupling, TESLA, controls, klystron	487
	V.P. Yakovlev Omega-P, Inc., New Haven, Connecticut J.L. Hirshfield Yale University, Physics Department, New Haven, CT S. Kazakov KEK, Ibaraki
	A fast, electrically-controlled tuner is described with parameters suitable for operation with the 9-cell SC accelerator structure of ILC. The tuner is based on a magic tee and two phase shifters that contain ferroelectric rings. The dielectric constant of the ferroelectric ring is altered by applying a 4.2 kV DC pulse that provides an RF phase shift from 0 deg to 180 deg. This, in turn allows a change of the input signal amplitude from zero to its maximum value, or a change in phase from 0 deg to 360 deg during the RF pulse. It is shown that the possibility of changing the cavity coupling to the input line during the RF pulse allows significant RF power savings, up to 12.5 MW for the 800 GeV ILC option. In addition, fast electrically-tuned amplitude and phase control with a feed-back system should be useful to compensate for possible phase deviations of the input RF fields in each cavity of ILC to match the cavity with the feeding transmission line as the beam load varies.

MOPLS006	Adaptive RF Transient Reduction for High Intensity Beams with Gaps	LHC, simulation, beam-losses, synchrotron	541
	J. Tuckmantel, P. Baudrenghien CERN, Geneva
	When a high-intensity beam with bunch-trains and gaps passes a cavity with a high-gain vector feedback enforcing a constant voltage, large transients appear, stressing the RF high power hardware and increasing the trip rate. By modulating the cavity voltage with a varying periodic waveform (set-function), the RF power can be made constant while still preserving the high feedback gain. The average cavity voltage is conserved but bunches have to settle at slightly shifted positions. A method is derived to obtain this set-function in practice while making no assumptions or measurements of the beam or RF parameters. Adiabatic iterations are made, including the whole machine as an analog computing device, using all parameters as they are. A computer simulation shows the success of the method.

MOPLS023	Status of Fast IR Orbit Feedback at RHIC	RHIC, dipole, power-supply, injection	589
	C. Montag, J. Cupolo, J. Glenn, V. Litvinenko, A. Marusic, W. Meng, R.J. Michnoff, T. Roser, C. Schultheiss, J.E. Tuozzolo BNL, Upton, Long Island, New York
	To compensate modulated beam-beam offsets caused by mechanical vibrations of IR triplet quadrupoles at frequencies around 10 Hz, a fast IR orbit feedback system has been developed. We report design considerations and recent status of the system.

MOPLS028	DAFNE Status Report	luminosity, injection, collider, interaction-region	604
	A. Gallo, D. Alesini, M.E. Biagini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G.O. Delle Monache, E. Di Pasquale, G. Di Pirro, A. Drago, A. Ghigo, S. Guiducci, M. Incurvati, P. Iorio, C. Ligi, F. Marcellini, C. Marchetti, G. Mazzitelli, C. Milardi, L. Pellegrino, M.A. Preger, L. Quintieri, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Vescovi, M. Zobov INFN/LNF, Frascati (Roma) G. Benedetti CELLS, Bellaterra (Cerdanyola del Vallès) L. Falbo INFN-Pisa, Pisa J.D. Fox, P. Raimondi, D. Teytelman SLAC, Menlo Park, California E. Levichev, S.A. Nikitin, P.A. Piminov, D.N. Shatilov BINP SB RAS, Novosibirsk
	The operation of DAFNE, the 1.02 GeV c.m. e⁺e^- collider of the Frascati National Laboratory with the KLOE detector, started in April 2004 has been concluded at the end of March 2006 with a total delivered luminosity of 2 fb-1 on the peak of the Phi resonance, 0.2 fb-1 off peak and a high statistics scan of the resonance. The best performances of the collider during this run have been a peak luminosity of 1.5 1032 cm-2s-1 and a daily delivered luminosity of 10 pb-1. The KLOE detector has been removed from one of the two interaction regions and its low beta section substituted with a standard magnetic structure, allowing for an easy vertical separation of the beams, while the FINUDA detector has been moved onto the second interaction point. Several improvements on the rings have also been implemented and are described together with the results of machine studies aimed at improving the collider efficiency and testing new operating conditions.

MOPLS031	Beam Orbit Control System for the KEKB Crab Cavities	target, controls, KEKB, damping	613
	M. Masuzawa, Y. Funakoshi, T.T. Nakamura, J.-I. Odagiri KEK, Ibaraki
	KEKB is an electron-positron collider with an 8 GeV electron ring (HER) and a 3.5 GeV positron ring (LER). The two beams currently collide at one interaction point with a finite horizontal crossing angle of 11 mrad. The design luminosity of 10 /nb/sec was first reached in May 2003 and the peak luminosity exceeded 16 /nb/sec in December 2005. Simulations predict a luminosity boost if a crab crossing scheme is introduced. The installation of two superconducting crab cavities, one in each ring, is scheduled in March 2006 in order to implement the crab crossing scheme. For stable operation, the horizontal beam position in the crab cavity must be carefully controlled. This is needed to avoid loss of control of the crabbing mode field due to beam loading. A beam position feedback system at the crab cavity has been prepared and tested. Its performance will be discussed in this report.

MOPLS033	Beam-beam Limit and Feedback Noise	damping, luminosity, radiation, kicker	619
	K. Ohmi, Y. Funakoshi, S. Hiramatsu, K. Oide, M. Tobiyama KEK, Ibaraki
	Beam-beam interaction is strongly nonlinear, therefore particles in the beam experience chaotic motion. A small noise can be enhanced by the chaotic nature, with the result that unexpected emittance growth can be observed. We study the noise of transverse bunch by bunch feedback system and related luminosity degradation. Similar effects caused by crab cavity noise is also discussed.

MOPLS042	Longitudinal Beam Stability for CESR-c	luminosity, positron, synchrotron, storage-ring	634
	R. Holtzapple, J.S. Kern, P.J.S. Stonaha Alfred University, Alfred, New York B. Cerio Colgate University, Hamilton, New York M.A. Palmer Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
	The Cornell Electron-Positron Storage Ring (CESR) operates at 1.9 GeV per beam for high energy physics collisions. To maintain high luminosity it is essential for the bunch trains to be longitudinally stable. Measurements of longitudinal stability with a single, multiple, and colliding trains have been performed using a dual sweep streak camera and are presented in this paper.

MOPLS051	Tracking Down a Fast Instability in the PEP-II LER	vacuum, SLAC, beam-losses, damping	658
	U. Wienands, R. Akre, S.C. Curry, S. DeBarger, F.-J. Decker, S. Ecklund, A.S. Fisher, S.A. Heifets, A. Krasnykh, A. Kulikov, A. Novokhatski, J. Seeman, M.K. Sullivan, D. Teytelman, D. Van Winkle, G. Yocky SLAC, Menlo Park, California
	During Run 5, the beam in the PEP-II Low Energy Ring (LER) became affected by a predominantly vertical instability with very fast growth rate of 10…60/ms - much faster than seen in controlled grow-damp experiments - and varying threshold. The coherent amplitude of the oscillation was limited to approx. 1 mm pk-pk or less and would damp down over a few tens of turns; however, beam loss set in even as the measured amplitude damped, causing a beam abort. This led to the conclusion that the beam was actually blowing up. The presence of a 2 nu_s line in the spectrum suggested a possible head-tail nature of the instability, although chromaticity was not effective in raising the threshold. In this paper we will describe the measurements and data taken to isolate and locate the cause of the instability and, eventually, the discovery and fix of the root cause.

MOPLS122	Design of the ILC Prototype FONT4 Digital Intra-train Beam-based Feedback System	kicker, extraction, linear-collider, KEK	849
	P. Burrows Queen Mary University of London, London G.B. Christian, H. Dabiri Khah, A.F. Hartin, G.R. White JAI, Oxford C.C. Clarke, C. Perry OXFORDphysics, Oxford, Oxon A. Kalinin CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire D.J. McCormick, S. Molloy, M.C. Ross SLAC, Menlo Park, California
	We report on the design and initial testing of the 4th generation Feedback on Nanosecond Timescales (FONT) prototype intra-train beam-based feedback system for beam control and luminosity optimisation at the International Linear Collider (ILC). FONT4 comprises a fast-analogue front-end BPM signal processor, with an FPGA-based digital feedback processor and a fast-risetime kicker-driver amplifier. The system is being designed with a total latency budget (including signal propagation delays) of about 140ns. FONT4 will be deployed at the Accelerator Test Facility (ATF) at KEK, where it will be tested with the electron bunchtrain extracted from the ATF damping ring. The bunches will have a spacing of c. 150ns, chosen to match the ILC design. We report the results of initial beam tests of the system components. We aim to demonstrate feedback, with delay-loop operation, on this ILC-like bunchtrain.

MOPLS123	Performance of the FONT3 Fast Analogue Intra-train Beam-based Feedback System at ATF	kicker, linear-collider, SLAC, CLIC	852
	P. Burrows Queen Mary University of London, London G.B. Christian, A.F. Hartin, H.D. Khah, G.R. White JAI, Oxford C.C. Clarke, C. Perry OXFORDphysics, Oxford, Oxon A. Kalinin CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire D.J. McCormick, S. Molloy, M.C. Ross SLAC, Menlo Park, California
	We report on the design and testing of the 3rd generation Feedback On Nanosecond Timescales (FONT) prototype intra-train beam-based feedback system for beam control and luminosity optimisation at the International Linear Collider (ILC). The all-analogue FONT3 electronics was designed to have an ultra-short latency of c. 10ns. We describe the design of the BPM signal processor, feedback circuit and kicker-driver amplifier. We report on deployment of FONT3 at the Accelerator Test Facility (ATF) at KEK, where it was tested with the 56ns-long electron bunchtrain extracted from the ATF damping ring. Feedback, with delay-loop operation, on the beam was demonstrated with a latency close to design. We comment on the applicability of this technology to ILC, as well as future warm-RF based linear colliders, such as CLIC.

TUYPA02	High Precision SC Cavity Alignment Diagnostics with HOM Measurements	dipole, alignment, linac, diagnostics	920
	J.C. Frisch, L. Hendrickson, J. May, D.J. McCormick, S. Molloy, M.C. Ross, T.J. Smith SLAC, Menlo Park, California N. Baboi, O. Hensler, L.M. Petrosyan DESY, Hamburg N.E. Eddy, S. Nagaitsev Fermilab, Batavia, Illinois O. Napoly, R. Paparella, C. Simon CEA, Gif-sur-Yvette
	Experiments at the TTF at DESY have demonstrated that the Higher Order Modes induced in Superconducting Cavities can be used to provide a variety of beam and cavity diagnostics. The centers of the cavities can be determined from the beam orbit which produces minimum power in the dipole HOM modes. The phase and amplitude of the dipole modes can be used as a high resolution beam position monitor, and the phase of the monopole modes to measure the beam phase relative to the accelerator RF. Beam orbit feedback which minimizes the dipole HOM power in a set of structures has been demonstrated. For most SC accelerators, the existing HOM couplers provide the necessary signals, and the downmix and digitizing electronics are straightforward, similar to those for a conventional BPM.
	Transparencies

TUYPA03	Developments in Beam Instrumentation and New Feedback Systems for the ILC	laser, damping, KEK, controls	925
	H. Hayano KEK, Ibaraki
	This presentation will review the challenging beam properties that need to be measured and controlled and new diagnostic developments that address these challenges for ILC beam instrumentation.
	Transparencies

TUOCFI03	RF Cavity with Co-based Amorphous Core	acceleration, impedance, synchrotron, controls	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

TUODFI02	DAFNE Experience with Negative Momentum Compaction	electron, positron, luminosity, lattice	989
	M. Zobov, D. Alesini, M.E. Biagini, A. Drago, A. Gallo, C. Milardi, P. Raimondi, B. Spataro, A. Stella INFN/LNF, Frascati (Roma)
	There are several potential advantages for a collider operation with a lattice having a negative momentum compaction factor (alfa): bunches can be shorter and have a more regular shape; longitudinal beam-beam effects and synchrobetatron resonances are predicted to be less dangerous; requirements on sextupole strengths can be relaxed because there is no head-tail instability with the negative chromaticity. Since the lattice of the Frascati e⁺e^- Phi-factory DAFNE is flexible enough to provide collider operation with alfa < 0, we have exploited this possibility to study experimentally the beam dynamics. The negative momentum compaction lattices have been successfully implemented and stable 1 A currents have been stored in both the electron and positron rings without any problem for RF cavities and feedback systems operation. First collisions have been tested at low currents. In this paper we describe the experimental results and compare them with expectations and numerical simulations. Present limitations to DAFNE operation with alfa < 0 are also discussed.
	Transparencies

TUPCH004	Commissioning of the LNLS X-ray BPMs	electron, diagnostics, dipole, synchrotron	998
	S.R. Marques, P.F. Tavares LNLS, Campinas
	We present experimental results of the commissioning of staggered-pair blade X-Ray beam position monitor (XBPM) recently developed and installed at the diagnostic beamline of the UVX electron storage ring at the Brazilian Synchrotron Light Laboratory (LNLS). The results obtained with a prototype XBPM indicate that the short-term and long-term data are both in agreement with the data from a commercially acquired XBPM installed at the same beamline, as well as with the data of the electron storage ring RF BPMs. In this paper we present the commissioning results of the LNLS XBPM.

TUPCH011	Innovative Beam Diagnostics for the Challenging FAIR Project	diagnostics, synchrotron, ion, cryogenics	1016
	P. Forck, A. Peters GSI, Darmstadt
	The planned FAIR facility consists of two heavy ion synchrotrons and four large storage rings. The super-conducting synchrotrons are build for high current operation and secondary ion production. A large variety of low current secondary beams is stored and cooled in the four storage rings. A complex operation scheme with multiple use of transport lines is foreseen. This demands an exceptional high dynamic range for the beam instrumentation. Due to the enormous beam power, non-destructive methods are mandatory for high currents. For the low current secondary beams, non-destructive diagnostics are also preferred due to the low repetition rate. Precise measurements of all beam parameters and automatic steering or feedback capabilities are required due to the necessary exploitation of the full ring acceptances. Moreover, online beam-corrections with short response times are mandatory for the fast ramping super-conducting magnets. Due to the ultra-high vacuum condition and the demanding measurement accuracy, novel technical solution are foreseen. An overview of the challenges and projected innovative solutions for various diagnostic installations will be given.

TUPCH012	Digital Techniques in BPM Measurements at GSI-ISI	acceleration, pick-up, synchrotron, GSI	1019
	A.A. Galatis, P. Kowina, K. Lang, A. Peters GSI, Darmstadt
	In this paper we describe new approaches for BPM measurements in hadron accelerators, which have strongly varying beam parameters such as intensity, accelerating frequency and bunch length. Following signal dynamic adjustment, direct digitalization and treatment of digitized data, we should reach a BPM resolution of 0.1mm. Interchangeability of this method between accelerators should be provided, which results in autonomous data treatment algorithms, free of external status and timing signalling. This should ensure the usability of the system in other bunched accelerator rings. Different operation modes are intended for allowing online storage of beam position data over full acceleration cycles as well as storage of beam waveforms in regions of acceleration that are of special interest e.g. transition, kicking, bunch gymnastics. First results of realised hardware/software combinations will be introduced and discussed.

TUPCH028	Layout of the Optical Synchronization System for FLASH	laser, electron, diagnostics, DESY	1061
	A. Winter, P. Schmüser, A. Winter Uni HH, Hamburg F. Loehl, F. Ludwig, H. Schlarb, B. Schmidt DESY, Hamburg
	The present RF synchronization system of the VUV-FEL can typically stabilize the arrival time of the electron bunches at the undulator to about 200 fs on a timescale of minutes and to several picoseconds on a timescale of hours. To improve the machine stability and to ensure optimal performance for the VUV-FEL user facility, a new ultra-precise timing system is mandatory. The optical synchronization system under construction will satisfy three goals: Firstly, it provides a local oscillator frequency with the same stability as the existing low-level RF regulation, secondly, it can synchronize the experimental lasers of the FEL users with a precision in the order of 30 fs, thirdly, it provides an ultra-stable reference for beam arrival time measurements and enables a feedback on the electron beam to compensate residual drifts and timing jitter. The optical synchronization system is based on an optical pulse train from a mode-locked laser with a highly stabilized repetition rate. This paper describes the proposed layout of the optical synchronization system, the integration into the machine layout and the diagnostic experiments to monitor the performance of the system.

TUPCH029	High-precision Laser Master Oscillators for Optical Timing Distribution Systems in Future Light Sources	laser, FEL, linac, DESY	1064
	A. Winter, P. Schmüser, A. Winter Uni HH, Hamburg J. Chen, F.X. Kaertner MIT, Cambridge, Massachusetts F.O. Ilday Bilkent University, Bilkent, Ankara F. Ludwig, H. Schlarb DESY, Hamburg
	X-ray pulses with a pulse duration in the 10 fs regime or even less are needed for numerous experiments planned at next generation free electron lasers. A synchronization of probe laser pulses to the x-ray pulses with a stability on the order of the pulse width is highly desirable for these experiments. This requirement can be fulfilled by distributing an ultra-stable timing signal to various subsystems of the machine and to the experimental area to provide synchronization at the fs level over distances of several kilometers. Mode-locked fiber lasers serve as laser master oscillators (LMO), generating the frequencies required in the machine. The pulse train is distributed through length-stabilized fiber links. This paper focuses on the LMO, devoting special attention to the phase noise properties of the frequencies to be generated, its reliability to operate in an accelerator environment, and the residual timing jitter and drifts of the RF feedback for the fiber links. A prototype experimental system has been constructed and tested in an accelerator environment and its performance characteristics will be evaluated.

TUPCH059	Dual-mode Beam Current Monitor	pick-up, impedance, 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.

TUPCH103	New Developments on Single-shot Fiber Scope	SLAC, laser, controls	1253
	Y. Yin, X. Che Y.Y. Labs, Inc., Fremont, California
	New development has been done to reduce the noise and improve the stability of the single-shot fiber scope, which used an optical fiber recirculating delay line to regenerate the single-shot very short electrical pulse, so a sampling scope can recover the original signal. New measurements have been done and will be reported.

TUPCH117	Experience with the 208MHz and 52MHz RF Systems for the HERA Proton Accelerator	beam-loading, controls, DESY, injection	1289
	R. Wagner, S. Choroba, A. Gamp, T.G. Grevsmuehl, G.M. Moeller DESY, Hamburg A.B. Bienkowski The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
	The RF System for the Hera Proton Ring consists of four 208MHz systems and two 52MHz systems. At injection three of the 208MHz systems are at 70 kV and one System is at 190kV with a phase of 180 degree. The 52 MHz Systems are at 70kV each. During ramping the RF voltage of all cavities follows a ramp table. At flat top at 920GeV both 52 MHz systems are at 50kV and three of the 208MHz Systems are at 190kV while the 180 degree phased system is reduced to 30kV. The typical beam current is 100mA in 180 bunches with a bunch separation of 96 ns. About one year before shutdown of HERA this presentation gives an review of about 14 years operation of the Proton RF System. It is also an overview of the hardware including the beam loading compensation (fast feedback) the tuning system and the other components.

TUPCH136	Phase Measurement and Compensation System in PLS 2.5 GeV Linac for PAL-XFEL	linac, klystron, XFEL, electron	1337
	W.H. Hwang, J. Choi, Y.J. Han, J.Y. Huang, H.-G. Kim, S.-C. Kim, I.S. Ko, W.W. Lee PAL, Pohang, Kyungbuk
	In PAL, We are preparing the 3.7 GeV PALXFEL project by upgrading the present 2.5GeV Linac. In present PLS Linac, the specifications of the beam energy spread and rf phase are 0.6%(peak) and 3.5 degrees(peak) respectively. And the output power of klystron is 80 MW at the pulse width of 4 ? and the repetition rate of 10 Hz. In XFEL, the specifications of the beam energy spread and rf phase are 0.03%(rms) and 0.01 degrees(rms) respectively. We developed an analogue and a digital phase measurement and rf phase compensation system for stable beam quality. This paper describes the microwave system for the PALXFEL and the rf phase measurement and phase compensation system.

TUPCH151	ERLP/4GLS Low Level Radio Frequency System	controls, ERLP, linac, laser	1376
	A.J. Moss, P.A. Corlett, J.F. Orrett, J.H.P. Rogers CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	The Energy Recovery Linac Prototype (ERLP) being constructed at Daresbury Laboratory will use an analog-based low level RF (LLRF) control system designed and built at FZR Rossendorf. Once the machine is operational, the testing and development of a digital LLRF feedback system will take place using the ERLP as a testbed.

TUPCH186	Low Level RF System Development for SOLEIL	SOLEIL, simulation, beam-loading, damping	1447
	P. Marchand, M.D. Diop, F. Ribeiro, R.S. Sreedharan SOLEIL, Gif-sur-Yvette M. Luong, O. Piquet CEA, Gif-sur-Yvette
	The Low Level RF system that is used in the SOLEIL storage ring consists in fully analog "slow" amplitude, phase and frequency loops, complemented with a direct RF feedback. A fast digital FPGA-based I/Q feedback, currently under development, will be implemented later on. The performance of both systems has been evaluated using a Matlab-Simulink-based simulation tool. The computed and first experimental results are reported.

TUPCH187	DSP-based Low Level RF Control as an Integrated Part of DOOCS Control System	controls, linac, DESY, electron	1450
	V. Ayvazyan, A. Brandt, O. Hensler, G.M. Petrosyan, L.M. Petrosyan, K. Rehlich, S. Simrock, P. Vetrov DESY, Hamburg
	The Distributed Object Oriented Control System (DOOCS) has been developed at DESY as a control system for TTF/VUV-FEL. The DSP based low level RF control system is one of the main subsystems of the linac. Several DOOCS device servers and client applications have been developed to integrate low level RF control into the TTF/VUV-FEL control system. The DOOCS approach defines each hardware device as a separate object and this object is represented in a network by a device server, which handles all device functions. A client application can have access to the server data using the DOOCS application programming interface. A set of generic and specially devoted programs provide the tools for the operators to control the RF system. The RF operation at the linac is being automated by the implementation of DOOCS finite state machine servers.

TUPCH190	Universal Controller for Digital RF Control	controls, resonance, klystron, beam-loading	1459
	S. Simrock DESY, Hamburg W. Cichalewski, M.K. Grecki, G.W. Jablonski TUL-DMCS, Lodz W.J. Jalmuzna Warsaw University of Technology, Institute of Electronic Systems, Warsaw
	Digital RF control systems allow to change the type of controller by programming of the algorithms executed in FPGAs and/or DSPs. It is even possible to design a universal controller where the controller mode is selected by change of parameters. The concept of a universal controller includes the self-excited-loop (SEL) and generator driven resonator (GDR) concept, the choice of I/Q and amplitude or phase control, and allows for different filters (including Kalman filter and method of optimal controller synthesis) to be applied. Even time-varying mixtures of these modes are possible. Presented is the implementation of such a controller and the operational results with a superconducting cavity.

TUPCH191	Considerations for the Choice of the Intermediate Frequency and Sampling Rate for Digital RF Control	controls, laser, DESY, simulation	1462
	S. Simrock, M. Hoffmann, F. Ludwig DESY, Hamburg M.K. Grecki, T. Jezynski TUL-DMCS, Lodz
	Modern FPGA-based rf control systems employ digital field detectors where an intermediate frequency (IF) in the range of 10 to more than 100 MHz is sampled with a synchronized clock. Present ADC technology with 14-16 bit resolution allows for maximum sampling rates up to 250 MHz. While higher IF's increase the sensitivity to clock jitter, lower IF frequencies are more susceptible to electromagnetic noise. The choice of intermediate frequency and sampling rate should minimize the overall detector noise, provide high measurement bandwidth and low latency in field detection, and support algorithms for optimal field estimation.

TUPCH195	The LHC Low Level RF	klystron, controls, LHC, injection	1471
	P. Baudrenghien, G. Hagmann, J.C. Molendijk, R. Olsen, A. Rohlev, V. Rossi, D. Stellfeld, D. Valuch, U. Wehrle CERN, Geneva
	The LHC RF consists in eight 400 MHz superconducting cavities per ring, with each cavity independently powered by a 300 kW klystron, via a circulator. The challenge for the Low Level is to cope with both very high beam current (more than 1A RF component) and excellent beam lifetime (emittance growth time in excess of 25 hours). For each cavity we have a Cavity Controller rack with two VME crates implementing a strong RF Feedback, a Tuner Loop with a new algorithm, a Klystron Ripple Loop and a Conditioning system. In addition each ring has a Beam Control system (four VME crates) including Frequency Program, Phase Loop, Radial Loop and Synchronization Loop. A Longitudinal Damper (dipole and quadrupole mode) acting via the 400 MHz cavities is included to reduce emittance blow-up due to filamentation following phase and energy errors at injection. Finally an RF Synchronization system implements the bunch into bucket transfer from the SPS into each LHC ring. When fully installed in 2007 the whole system will count over three hundreds home-designed VME cards of twenty-three different models installed in fourty-five VME crates.

TUPCH196	Digital Design of the LHC Low Level RF: the Tuning System for the Superconducting Cavities	controls, LHC, CERN, diagnostics	1474
	J.C. Molendijk, P. Baudrenghien, A. Butterworth, E. Ciapala, R. Olsen, F. Weierud CERN, Geneva R. Sorokoletov JINR, Dubna, Moscow Region
	The low level RF systems for the LHC are based extensively on digital technology, not only to achieve the required performance and stability but also to provide full remote control and diagnostics facilities needed in a machine where most of the RF system is inaccessible during operation. The hardware is based on modular VME but with additional low noise linear power supplies and a specially designed P2 backplane for timing distribution and fast data interchange. Extensive design re-use and the use of graphic FPGA design tools have streamlined the design process. A milestone was the test of the tuning system for the superconducting cavities. The tuning control module is based on a 2M gate FPGA with on-board DSP. Its design and functionality are described, including features such as automatic measurements of cavity characteristics and transient response of the tuning system. The tuner control is used as a test bed for LHC standard software components. A full 'vertical slice' from remote application down to the hardware has been tested. Work is ongoing on the completion of other modules and building up the software and diagnostics facilities needed for RF system commissioning.

TUPCH197	Low level RF System Development for the Superconducting Cavity in NSRRC	controls, klystron, FIR, linac	1477
	M.-S. Yeh, L.-H. Chang, F.-T. Chung, K.-T. Hsu, Y.-H. Lin, C. Wang NSRRC, Hsinchu
	The present low level system in NSRRC is based on analogy feedback control scheme. It provides feedback regulation on EM field, phase, and resonant frequency of the superconducting RF cavity. In order to address the required flexibility and improve diagnostic of the RF control system, a new digital low-level RF system based on Field Programmable Gate Array (FPGA) is proposed to be develop in house. The status of current analogy low level RF system and the specification of new digital FPGA based low level RF system are reposted herein.

TUPCH200	Amplitude Linearizers for PEP-II 1.2 MW Klystrons and LLRF Systems	klystron, controls, impedance, 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.

TUPLS114	An Improvement of Matching Circuit of RF Kicker Electrodes	extraction, controls, kicker, impedance	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.

WEXPA03	Digital Low Level RF	controls, linac, collider, CERN	1847
	M.-E. Angoletta CERN, Geneva
	The demand on high stability and precision on the RF voltage for modern accelerators, as well as better diagnostics, maintenance and flexibility is driving the community to develop Digital Low Level RF systems (DLLRF) for the new linear accelerators, but also for synchrotrons. An overview of the state of the art in digital technologies applied to DLLRF systems and an overview of the different designs developed or in development at the different labs will be presented.
	Transparencies

WEYPA01	Beam Delivery System in ILC	linac, quadrupole, electron, luminosity	1852
	G.A. Blair Royal Holloway, University of London, Surrey
	The presentation will review the challenges of this key ILC sub-system in terms of beam performances, machine protection system, collimation, interaction with the detector and compare them with the achievements in SLC and FFTB. It will then present the world-wide organization to define and make the necessary R&D for the design, beam simulations and benchmarking in tests facilities, especially the ATF2 facility under construction at KEK. It will explore the major issues both from the beam dynamics and the technological point of view, as well as the plans foreseen and the schedule to address them. It will finally analyze the possible upgrade in energy together with the possible limitations and associated issues.
	Transparencies

WEPCH020	Extending the Linear Least Squares Problem for Orbit Correction in Circular Accelerators	controls, ELETTRA, simulation, insertion	1963
	C. Scafuri ELETTRA, Basovizza, Trieste
	A method for extending the linear least squares problem applicable for correcting the orbit of circular accelerators is proposed. The method is based on the definition of a suitable cost function which weighs both orbit deviations and the correction effort, that is steerer kicks. The paper presents the full derivation of the formulas and the results of simulations. The application of this method for the Global Orbit Feedback system of the ELETTRA storage ring is being evaluated.

WEPCH025	COD Correction at the PF Ring by New Orbit Feedback Scheme	simulation, insertion, insertion-device, electron	1978
	K. Harada, T. Obina KEK, Ibaraki N. Nakamura, H. Sakai, H. Takaki ISSP/SRL, Chiba
	When we correct the global COD (closed orbit distortion), if we use the modified conversion matrix calculated by the eigen vector method with constraint conditions (EVC), the local orbit correction can be simultaneously done to fix the light source point in the insertion device. In the EVC, the local orbit correction is combined to the global orbit correction by the Lagrange's undetermined multiple method. In this paper, we show the machine study results at the PF Ring.

WEPCH128	Virtual Accelerator as an Operation Tool at J-PARC 3 GeV Rapid Cycling Synchrotron (RCS)	betatron, simulation, synchrotron, optics	2224
	H. Harada, K. Shigaki Hiroshima University, Higashi-Hiroshima K. Furukawa KEK, Ibaraki H. Hotchi, F. Noda, H. Sako, H. Suzuki JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken S. Machida CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
	We developed a virtual accelerator based on EPICS for 3 GeV Rapid-Cycle Synchrotron (RCS) in J-PARC. It is important to have an on-line model of optics parameters, such as tunes, Twiss parameters, dispersion function, at the commissioning stage in a high intensity proton machine. It gives a strong feedback for the RCS operation as a commissioning tool as well as for the studies of beam dynamics issues. Beam position monitors with finite resolutions, a transverse exciter to measure the betatron frequency, and a RF system with variable frequency to simulate off-momentum optics have been implemented into the system. The virtual accelerator system itself and some results of beam dynamics studies will be presented.

WEPCH192	Compact Electron Linear Accelerator RELUS-5 for Radiation Technology Application	electron, power-supply, vacuum, controls	2385
	D.A. Zavadtsev, A.I. Fadin, A.A. Krasnov, N.P. Sobenin MEPhI, Moscow A.A. Zavadtsev Introscan, Moscow
	The electron linear accelerator for radiation technology application is designed to meet the following main requirements: 3-5 MeV energy, 3-6 microsecond pulse width, and 1 kW average beam power. The accelerating system is a 0.5 m long S-band standing wave on-axis coupled biperiodic structure. A 35-40 kV electron gun with spherical cathode is used as the injector. The RF generator is a 2.5 MW peak power 4 kW average power magnetron. The generated frequency is stabilized by a high Q-factor accelerating system connected into feed-back of the magnetron. The magnetron is fed by a compact 45-55 kV IGBT based modulator. The accelerator is controlled through a PLC-based control system.

WEPLS122	Multiphase Resonant Power Converter for High Energy Physics Applications	controls, power-supply, radio-frequency, klystron	2658
	M.J. Bland, J. Clare, P. W. Wheeler University of Nottingham, Nottingham
	Accelerators used for experiments in high-energy physics require very high power radio frequency sources to provide the energy needed to accelerate the particles. The RF power needs to be stable and predictable such that any variation in the supplied RF power has a limited and acceptable impact on the accelerated beam quality. This paper considers the design of a "long-pulse" modulator supply rated at 25kV, 10A (250kW peak power, duty ratio 10%, 25kW average power, pulse length ≈ 1 − 2ms). The supply is based on direct modulation of a multi-phase resonant power supply, fed by an active rectifier. The objectives of the development are to produce a compact power supply, with low stored energy and with high power quality at the utility supply. The paper provides a brief overview of the technology, followed by a discussion of the design choices. Initial results from the laboratory prototype will be included.

WEPLS134	Design and Modeling of the Step Down Piezo Transformer	impedance, controls, simulation, power-supply	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.

WEPLS139	Operational Status of Klystron-modulator System for PAL 2.5-GeV Electron Linac	klystron, linac, electron, SLAC	2703
	S.S. Park, J. Choi, J.Y. Huang, S.H. Kim, S.-C. Kim PAL, Pohang, Kyungbuk
	The klystron-modulator(K&M) system of the Pohang Accelerator Laboratory (PAL) generates high power microwaves for the acceleration of 2.5 GeV electron beams. There are 12 modules of K&M system to accelerate electron beams up to 2.5 GeV nominal beam energy. One module of the K&M system consists of the 200 MW modulator and an 80 MW S-band (2856 MHZ) klystron tube. The total accumulated high-voltage run-time of the oldest unit among the 12 K&M systems has reached nearly 88,000 hours as of December 2005. The overall system availability is well over 95%. In this paper, we review the overall system performance of the high-power K&M system and the operational status of the klystrons and thyratron lifetimes, and the overall system's availability will be analyzed for the period of 1994 to December 2005.

WEPLS143	SLS Operation Management: Methods and Tools	controls, SLS, diagnostics, power-supply	2715
	A. Lüdeke PSI, Villigen
	Users of 3rd generation synchrotron light sources desire not only a high flux on their samples and sub-micron beam stability, they expect at the same time a beam availability close to 100 percent. To reach and maintain a very high availability put special demands on the operation management of a light source. We will illustrate the procedures used at the Swiss Light Source (SLS) to deal with beam interruptions and explain the tools used for operation management.

THPPA01	High-precision Laser Master Oscillators for Optical Timing Distribution Systems in Future Light Sources	laser, electron, FEL, diagnostics	2747
	A. Winter, P. Schmüser, A. Winter Uni HH, Hamburg J. Chen, F.X. Kaertner MIT, Cambridge, Massachusetts F.O. Ilday Bilkent University, Bilkent, Ankara F. Ludwig, H. Schlarb DESY, Hamburg
	Abstract to be supplied
	Transparencies

THPCH045	Transverse Head-tail Modes Elimination with Negative Chromaticity and the Transverse Multi-bunch Feedback System at ELETTRA	ELETTRA, impedance, 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.

THPCH050	Further Studies on Betatron Sidebands due to Electron Clouds	electron, betatron, synchrotron, KEKB	2898
	J.W. Flanagan, H. Fukuma, Y. Funakoshi, S. Hiramatsu, T. Ieiri, H. Ikeda, K. Ohmi, K. Oide, M. Tobiyama KEK, Ibaraki
	We have observed vertical betatron sidebands in the transverse beam spectra of positron bunches at the KEKB LER which are associated with the presence of electron clouds in single-beam studies, and which are also associated with a loss of luminosity when the KEKB beams are in collision. The sidebands may be signals of a fast head-tail instability due to short-range wakes within the electron cloud, providing a diagnostic for exploring the mechanism for transverse beam blow-up due to electron clouds. We report here on further studies on the behavior of the sidebands under varying beam conditions, including varying initial beam size below the beam blow-up threshold, chromaticity, RF voltage and fill pattern. J. W. Flanagan et al. PRL 94, 054801 (2005).**J. W. Flanagan et al. Proc. PAC05, p. 680 (2005).

THPCH052	Dependence of Transverse Instabilities on Amplitude Dependent Tune Shifts	octupole, betatron, ion, factory	2904
	T. Miyajima, K. Harada, Y. Kobayashi, S. Nagahashi KEK, Ibaraki
	In the Photon Factory electron storage ring, transverse instabilities have been observed in multi-bunch operation mode. The instabilities can be suppressed by amplitude dependent tune shifts, which are induced by the sextupole, octupole and higher order magnetic field. Since four octupole magnets have been installed in the PF ring, we can control the tune shifts, which is caused by the octupole magnetic field, independently of chromaticities, which is caused by sextupole magnetic field. In order to research the suppression mechanism of the instabilities, we measured the dependence of the instabilities on the tune shifts, which are induced by the octupole field. The threshold of the tune shifts, which suppress the instabilities, were observed in the measurement, and it depended on the filling pattern of the bunch train and the beam current per bunch. In addition, we will present the results of the measurement before and after the reconstruction for the straight-sections upgrade at the PF ring, which was carried out in 2005.

THPCH077	Resistive-wall Instability in the Damping Rings of the ILC	impedance, 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.

THPCH082	Broadband Bunch by Bunch Feedback for the ESRF using a Single High Resolution and Fast Sampling FPGA DSP	kicker, damping, FIR, pick-up	2976
	E. Plouviez, P. Arnoux, F. Epaud, J. Jacob, J.M. Koch, N. Michel, G.A. Naylor, J.-L. Revol, V. Serriere, D. Vial ESRF, Grenoble
	In order to increase the current in the ESRF storage ring we have developed a set of multibunch feedback systems aimed at fighting longitudinal and transverse coupled bunch instabilities. The longitudinal feedback (LFB) has been the first system installed and tested. It was designed using the scheme developed at SLAC, ALS and INFN Frascati: bunch by bunch processing of a beam phase error signal and correction using a low Q kicker driven by a QPSK modulator. However, we took advantage for this development of the latest available technology for the signal processing electronics with high resolution, high sampling rate ADC and DAC, and FPGA DSP, as well as for the FPGA programming environment. It allowed us to substantially reduce the complexity: the algorithm runs on a single processor, the kicker requires only 200W of RF power to control a 6GeV beam, and the implementation took only about one year. We will describe the main features of our LFB and present the results already achieved in the damping of instabilities driven by our RF cavity HOM. We will also report on the status of the transverse feedback, which is being built up using the same FPGA system as the longitudinal one.

THPCH083	A Tune Feedback System for the HERA Proton Storge Ring	coupling, quadrupole, acceleration, proton	2979
	S.G. Brinker, S.W. Herb, F.J. Willeke DESY, Hamburg Th. Lohse Humboldt University Berlin, Institut für Physik, Berlin
	The transverse tunes of an accelerator or storage ring are important parameters which have to be controlled and adjusted continuously during beam operation in order to assure good experimental background conditions. For the HERA proton storage ring, persistent current effects of the superconducting magnets are the main source for the inadequate repeatability of the tunes without a feedback while the proton beam is accelerated. A tune feedback has been developed, implemented and tested during beam acceleration and luminosity operation. Considering the different conditions during energy ramps and luminosity runs two versions of this feedback system have been established based on different correction and peak-finding algorithms (e.g. wavelet analysis). No additional excitation is needed on top of the standard tune indication system in HERA. The tunes could be kept constant during beam accceleration with a standard deviation of delta Q = 0.003. In luminosity runs where the tune control is more critical, first tests resulted in a standard deviation which was a factor of ten smaller. The feedback system is implemented as a standard tool for beam acceleration.

THPCH084	Control Path of Longitudinal Multibunch-feedback System at HERA-p	controls, kicker, proton, FIR	2982
	F.E. Eints, S. Choroba, M.G. Hoffmann, U. Hurdelbrink, P.M. Morozov, J. Randhahn, S. Ruzin, S. Simrock DESY, Hamburg
	A longitudinal broadband damper system to control coupled bunch instabilities has been developed and installed in the proton accelerator HERA-p at the DESY. The control system consists of a control path and a Fast Diagnostic System (FDS) for oscillation diagnostic. The control path consists of FPGA-based digital controller, vector modulator, 1kW power amplifier, kicker-cavity and beam. In the FDS, the bunch phase signals are sampled by a digital FPGA board with 14Bit ADC (controller) with a sampling frequency of 10.4MHz. Phase calculation for all bunches and offset correction will be done by FPGA software which includes a digital filter. The filter has to be able to deal with a slowly changing synchrotron frequency. Here we consider a filter design which treats each of maximum 220 bunches as an independent oscillator which has to be damped. More sophisticated mode filter algorithms may be required to get better noise performance. The FPGA-board output signal modulates a 104 MHz sine-wave. The resulting logitudinal correction kick signal is provided by the kicker-cavity. Beside the technical details we present first operational experience and the actual system performance.

THPCH085	The Longitudinal Coupled Bunch Feedback for HERA-p	kicker, diagnostics, luminosity, controls	2985
	M.G. Hoffmann, S. Choroba, F.E. Eints, U. Hurdelbrink, P.M. Morozov, J. Randhahn, S. Ruzin, S. Simrock, E. Vogel, 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. This represents one of the attempts to increase the specific luminosity at HERA by reducing the bunch length. The final bunch length is defined by the initial emittance after injection and by the acceleration process where multiply occuring coupled bunch instabilities provoke bunch length blow up at discrete energies during the ramp. The actual feedback design consists of a fast, high precision bunch centroid phase detector, a 1~kW feedback cavity with 104~MHz centre frequency and 8~MHz bandwidth (FWHM), a I/Q-vector modulator, the low level digital FPGA-board with 14 Bit ADCs and DACs and a cavity transient diagnostics. The system measures the phases of all bunches and calculates corrections in real time (bunch spacing: 96~ns) which are then applied to the beam via a longitudinal kicker. The filter deals with a slowly changing synchrotron frequency (20-80 Hz).

THPCH086	Design of a Local IP Orbit Feedback at HERA-e	electron, proton, interaction-region, controls	2988
	J. Keil, O. Kaul, E. Negodin, R. Neumann DESY, Hamburg
	At the electron-proton collider HERA it is often observed that the proton emittance growth rate of colliding bunches is larger compared to non-colliding proton bunches. In addition the proton background rates are increasing when the two beams are brought into collision. There are indications that a contribution comes from closed orbit oscillations of the electron beam at the two IPs. In the arcs of HERA-e oscillation amplitudes of 100-200 micrometer with frequencies of 2-15 Hz and harmonics of 50 Hz are observed. In order to stabilize the orbit at the IPs in both planes a local digital orbit feedback system with a bandwidth of more than 20 Hz has been developed. The beam position at the IPs is measured with BPMs using dedicated electronics. The four local orbit bumps are produced by air-coil steerer magnets. The data are transmitted using SEDAC field bus lines to a central PC, which is used for the computation of the correction.

THPCH087	Design and Operation of a Ferrite Loaded Kicker Cavity for the Longitudinal Coupled Bunch Feedback for HERA-p	resonance, kicker, damping, impedance	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.

THPCH088	A Possibility of Constant Energy Extraction at the KEK ATF2	extraction, KEK, synchrotron, kicker	2994
	A. Kalinin CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	Beam energy oscillations of the order of 0.02% take place at the KEK ATF. With extractions, the synchrotron oscillation amplitude and phase at the extraction turn randomly fluctuates. The energy jitter causes a position/angle jitter in the Diagnostic section of the Extraction Line. To reduce it, a feed forward energy stabilisation can be used done by extraction of the beam at the turn next to that turn at which the energy passes the equilibrium value. For this, the synchrotron oscillation is measured by a turn-by-turn BPM as a horizontal position oscillation. A fast turn-by-turn processor detects the turn where the oscillation passes zero, and generates an extraction permission signal that triggers the existing ATF Extraction system. Stability improvement by factor of 10 can be obtained even when the extraction is done with uncertainty up to three turns after the trigger.

THPCH089	The Electromagnetic Background Environment for the Interaction-point Beam Feedback System at the International Linear Collider	background, SLAC, target, linear-collider	2997
	G.B. Christian, P. Burrows, G.B. Christian, C.C. Clarke, A.F. Hartin, C. Swinson, G.R. White OXFORDphysics, Oxford, Oxon R. Arnold, C. Hast, S. Smith, M. Woods SLAC, Menlo Park, California A. Kalinin CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	The Interaction Point (IP) feedback system is essential for maintaining the luminosity at the International Linear Collider (ILC). It is necessary to demonstrate the performance of the feedback beam position monitor (BPM) in an electron-positron pair background similar to that expected in the ILC interaction region (IR). We have simulated the ILC beam-beam interactions and used a GEANT model of the IR to evaluate the pair and photon flux incident on the BPM, for both the 2 mrad and 20 mrad crossing angle geometries. We present results as a function of the proposed machine parameter schemes, as well as for various system layouts within the IR. We plan to study the degradation of BPM resolution, and the long term survivability, in beam tests at End Station A at SLAC. To simulate the background environment of the ILC a 'spray beam' will be produced, which will scatter from a mechanical mock-up of the forward region of the IR, and irradiate the BPM with realistic flux of secondary pairs. We present the proposed experimental layout and planned beam tests.

THPCH091	Status of the ELETTRA Global Orbit Feedback Project	controls, electron, ELETTRA, closed-orbit	3003
	M. Lonza, D. Bulfone, R. De Monte, V. Forchi', G. Gaio ELETTRA, Basovizza, Trieste
	A fast digital feedback system is under development to stabilize the electron beam closed orbit at the ELETTRA storage ring in the band up to 300 Hz. In view of the implementation of the feedback, the existing orbit measurement system will be upgraded to allow for better accuracy in the beam position measurement and higher acquisition rate. A global correction algorithm running on a number of distributed processing units will correct the orbit using all of the storage ring steerer magnets. The status of the project development is given in this article.

THPCH092	Single-loop Two-dimensional Transverse Feedback for Photon Factory	FIR, damping, kicker, factory	3006
	T. Nakamura, K. Kobayashi JASRI/SPring-8, Hyogo-ken W.X. Cheng, T. Honda, M. Izawa, T. Obina, M. Tadano KEK, Ibaraki
	We installed a 500MS/s single-loop two-dimensional transverse bunch-by-bunch feedback system in the Photon Factory ring at KEK and the system is in operation at its user mode. The system composed of a single feedback loop; one skewed pair of BPM electrodes and one kicker stripline at skewed position to detect position and kick horizontally and vertically with a single signal line, and a SPring-8 feedback processor. Consequently, this system is easy to tune and cost effective. SPring-8 feedback processor employs FPGA that has enough computing power for processing more than 20-tap FIR filter required for newly developed two-dimensional feedback signal processing. We report the principle of the system, the result of test and the experience.

THPCH093	Bunch-by-bunch Feedback for the Photon Factory Storage Ring	damping, impedance, 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.

THPCH095	Transverse Damping System at SIS100	damping, kicker, injection, GSI	3014
	V. Zhabitsky, E. Gorbachev, N.I. Lebedev JINR, Dubna, Moscow Region U. Blell, P.J. Spiller GSI, Darmstadt
	The basic concept and main design features of the transverse damping system at the SIS100 synchrotron are presented. SIS100 with five times the circumference of the current SIS18 accelerator is a part of the Facility for Antiproton and Ion Research (FAIR) which is the next accelerator complex being constructed on the GSI site. The existing GSI accelerators serve as injector for SIS100. The SIS100 synchrotron will provide ion beams of high intensities which can lead to transversal and longitudinal beam instabilities. In order to damp the coherent transverse beam oscillations, a transverse feedback system (TFS) is going to be implemented in SIS100. The TFS presented is a feedback with a real-time digital signal processing for damping of transverse injection oscillations, feedback curing transverse coupled bunch instabilities, and excitation of transverse oscillations for beam measurements and other applications. The data on the bandwidth and gain of the TFS as well as the general description of the central processing unit are presented.

THPCH096	Intra Bunch Train Feedback System for the European X-FEL	pick-up, XFEL, coupling, controls	3017
	V. Schlott, M. Dehler, B. Keil, R. Kramert, A. Lounine, G. Marinkovic, P. Pollet, M. Roggli, T. Schilcher, P. Spuhler, D.M. Treyer PSI, Villigen
	After joining the preparatory phase of the European X-FEL project, the Paul Scherrer Institut (PSI) agreed in taking over responsibility for electron beam stabilization by developing a fast intra bunch train feedback (IBFB) system, which will be tested in its prototype version at the VUV-FEL facility at DESY. The IBFB will make use of the long bunch trains provided by the superconducting drive accelerators of the VUV- as well as the European X-FEL allowing to damp beam motions in a frequency range of a few kHz up to several hundreds of kHz applying modern control algorithms in a feedback loop. The FPGA-based, digital data processing and the low latency time (preferably < 200 ns) permit the elimination of long range (from bunch train to bunch train) and ultra fast (bunch by bunch) repetitive beam movements by adaptive feed forwards. In this paper, we will introduce the IBFB design concept and report on first test measurements with newly designed stripline beam position monitors for the VUV-FEL.

THPCH097	Commissioning of the Digital Transverse Bunch-by-bunch Feedback System for the TLS	FIR, kicker, damping, controls	3020
	K.H. Hu, J. Chen, P.J. Chou, K.-T. Hsu, S.Y. Hsu, C.H. Kuo, D. Lee, C.-J. Wang NSRRC, Hsinchu A. Chao SLAC, Menlo Park, California K. Kobayashi, T. Nakamura JASRI/SPring-8, Hyogo-ken W.-T. Weng BNL, Upton, Long Island, New York
	Multi-bunch instabilities degrade the beam quality leading to increased beam emittance, energy spread or even to beam loss. The feedback system is used to suppress multi-bunch instabilities due to resistive wall of the beam ducts, cavity-like structures and trapped ions. A new digital transverse bunch-by-bunch feedback system was commissioned at the Taiwan Light Source recently, and has replaced the previous analog system. The new system has the advantages that it enlarges the tune acceptance compared with the old system, enhances damping for transverse instability at high current, and as a result, top-up operation was achieved. In this new system, a single feedback loop simultaneously suppresses both the horizontal and vertical multi-bunch instabilities. The feedback system employs the latest generation FPGA feedback processor to process bunch signals. Memory installed to capture up to 250 msec bunch oscillation signal has included the considerations for system diagnostic and should be able to support various beam physics study.

THPCH098	FPGA-based Longitudinal Bunch-by-bunch Feedback System for TLS	kicker, FIR, impedance, 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.

THPCH099	A Turn-by-turn, Bunch-by-bunch Diagnostics System for the PEP-II Transverse Feedback Systems	controls, SLAC, damping, injection	3026
	R. Akre, W.S. Colocho, A. Krasnykh, V. Pacak, R. Steele, U. Wienands SLAC, Menlo Park, California
	A diagnostics system centered around commercial fast 8-bit digitizer boards has been implemented for the transverse feedback systems at PEP-II. The boards can accumulate bunch-by-bunch position data for 4800 turns (35 ms) in the x plane and the y plane. A dedicated trigger chassis allows to trigger the data acquisition on demand, or on an injection shot to diagnose injection problems, and provides gating signals for grow-damp measurements. Usually, the boards constantly acquire data and a beam abort stops data acquitision, thus preserving the last 4800 turns of position information before a beam abort. Software in a local PC reads out the boards and transfers data to a fileserver. Matlab-based data analysis software allows to present the raw data but also higher-level functions like spectra, modal analysis, spectrograms and other functions. The system has been instrumental in diagnosing beam instabilities in PEP. This paper will describe the architecture of the system and its applications.

THPCH100	New Fast Dither System for PEP-II	luminosity, controls, SLAC, closed-orbit	3029
	S.M. Gierman, S. Ecklund, R.C. Field, A.S. Fisher, P. Grossberg, K.E. Krauter, E.S. Miller, M. Petree, K.G. Sonnad, N. Spencer, M.K. Sullivan, K.K. Underwood, U. Wienands SLAC, Menlo Park, California
	The PEP-II B-Factory uses multiple feedback systems to stabilize the orbits of its stored beams and to optimize their performance in collision [1]. This paper describes an upgrade to the feedback system responsible for optimizing the overlap of colliding beams at the interaction point (IP). The effort was motivated by a desire to shorten the response time of the feedback, particularly in the context of machine-tuning tasks. We describe the original feedback system, the design for the new one, and give a status report on the installation.

THPCH101	Modeling and Simulation of Longitudinal Dynamics for LER-HER PEP II Rings	simulation, klystron, impedance, 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.

THPCH102	Fast Global Orbit Feedback System in SPEAR3	controls, power-supply, undulator, diagnostics	3035
	A. Terebilo, T. Straumann SLAC, Menlo Park, California
	New digital global orbit feedback system is under commissioning in SPEAR3 light source. The system has 4kHz sampling rate and 200Hz bandwidth. Correction algorithm is based on Singular Value Decomposition (SVD) of the orbit response matrix. For performance tuning and additional flexibility when adding or removing correctors and BPMs, we implemented an independent PID control loop for every orbit eigenvector used. This paper discusses performance of the new system and some advantages of multiple PID loops in the eigenvector space versus a single PID loop working on the raw orbit error.

THPCH103	Design and Testing of Gproto Bunch-by-bunch Signal Processor	diagnostics, luminosity, damping, injection	3038
	D. Teytelman, R. Akre, J.D. Fox, A. Krasnykh, C.H. Rivetta, D. Van Winkle SLAC, Menlo Park, California A. Drago INFN/LNF, Frascati (Roma) J.W. Flanagan, T. Naito, M. Tobiyama KEK, Ibaraki
	A prototype programmable bunch-by-bunch signal acquisition and processing channel with multiple applications in storage rings has been developed at SLAC. The processing channel supports up to 5120 bunches with bunch spacings as close as 1.9 ns. The prototype has been tested and operated in five storage rings: SPEAR-3, DAFNE, PEP-II, KEKB, and ATF damping ring. The testing included such applications as transverse and longitudinal coupled-bunch instability control, bunch-by-bunch luminosity monitoring, and injection diagnostic. In this contribution the prototype design will be described and its operation will be illustrated with the data measured at the abovementioned accelerators.

THPCH104	Design and Simulation of the ILC Intra-train Orbit and Luminosity Feedback Systems	luminosity, simulation, kicker, linac	3041
	G.R. White, G.R. White JAI, Oxford D. Schulte CERN, Geneva N.J. Walker DESY, Hamburg
	To maintain luminosity to within a few percent of the design at the International Linear Collider (ILC), beam stability at the IP needs to be maintained at the sub-nanometre level. To achieve the beam stability required in the presence of ground motion, multiple feedback systems are required. The baseline design calls for a 5-Hz system to control the orbit in the Linac and Beam Delivery System (BDS) and an intra-train system to address high-frequency ground motion and mechanical disturbances which cause orbit distortions at the IP between pulses enough to completely destroy the luminosity. Details of the slower feedback systems have been addressed elsewhere. The detailed design and simulation of the intra-train feedback systems are described here. This system controls the vertical position and angle at the IP such that luminosity is maximised. The system brings the beams into collision based on BPM-derived information from the initial bunches of the train. It then tunes the IP collision parameters (both position and angle) based on a fast (bunch-by-bunch) luminosity signal from the BeamCal. The system is implemented in fast digital FPGA logic, designed using Matlab's Simulink. A. Seryi et al. "Issues of Stability and Ground Motion in ILC", Nanobeam 2005.**G. White et al. "Multi-Bunch Simulations of the ILC for Luminosity Performance Studies", PAC2005.

THPCH105	Summary of Coupling and Tune Feedback Results during RHIC Run 6, and Possible Implications for LHC Commissioning	coupling, RHIC, betatron, LHC	3044
	P. Cameron, A. Della Penna, L.T. Hoff, Y. Luo, A. Marusic, V. Ptitsyn, C. Schultheiss BNL, Upton, Long Island, New York M. Gasior, O.R. Jones CERN, Geneva C.-Y. Tan Fermilab, Batavia, Illinois
	Efforts to implement tune feedback during the acceleration ramp in RHIC have been hampered by the effect of large betatron coupling, as well as by the large dynamic range required by transition crossing with ion beams. Both problems have been addressed, the first by implementation of continuous measurement of coupling using the phase-locked tune meter, and the second by the development of the direct diode detection analog front end. Performance with these improvements will be evaluated during the first days of RHIC Run 6 beam commissioning. With positive results, the possibility of implementing operational feedback control of tune and coupling during beam commissioning will be considered. After beam commissioning, chromaticity feedback will be explored as a part of the accelerator physics experimental program. We will summarize the results of these investigations, and discuss possible implications of these results for LHC commissioning.

THPCH130	Design and Implementation of Analog Feedback Damper System for an Electron-proton Instability at the Los Alamos Proton Storage Ring	kicker, storage-ring, LEFT, impedance	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.

THPCH159	Analysis of Microphonic Disturbances and Simulation for Feedback Compensation	simulation, FEL, linac, resonance	3167
	M. Luong, P. Bosland, G. Devanz, E. Jacques CEA, Gif-sur-Yvette
	For FEL projects based on a superconducting linac operating in CW mode, the RF power optimization finally comes up against the microphonics disturbances, which result in an unpredictable detuning of the cavities. A new piezoelectric tuner was developed and mounted on a TTF 9-cell cavity with an appropriate instrumentation. This system enables a full characterization of the disturbances and the tuner behavior. First measurements were made in a horizontal cryomodule at 4.2 K. They set a basis for simulations to assess the possibility of a feedback compensation, which is usually credited as impracticable. The outcome of such a compensation is also shown in terms of acceleration voltage amplitude and phase residual errors.

THPLS011	Operation and Recent Development at the ESRF	ESRF, undulator, insertion, insertion-device	3290
	J.-L. Revol, J.C. Biasci, J-F. B. Bouteille, J. Chavanne, P. Elleaume, L. Farvacque, L. Hardy, J. Jacob, G.A. Naylor, E. Plouviez, A. Ropert, K.B. Scheidt ESRF, Grenoble
	We report on the achieved performance of the ESRF storage ring as well as developments accomplished or underway. A new hybrid filling mode based on groups of bunches and a 4-bunch filling pattern are now delivered to the users. Following the increasing demand of users for beam stability, the fast orbit feedback has been upgraded. The installation of 5 m-long, 8 mm vertical aperture NEG coated aluminum chambers is progressing at a rate of one chamber per shutdown. The increase in current from 200 to 300 mA is being prepared; however, operation in this mode is still impaired by HOM driven longitudinal instabilities. To overcome this difficulty, a longitudinal feedback is being commissioned. HOM damped cavities are also under study to possibly replace the existing five-cell cavities. The policy of preventive maintenance has been continued. However, in 2005 the machine availability was affected by water leaks occurring on front-end absorbers and on one dipole crotch absorber. The crotch absorbers suffer all from the same erosion process that could be delayed by a systematic vertical realignment, leaving time for procurement and replacement of the entire pool.

THPLS061	Status of the Swiss Light Source	SLS, coupling, booster, injection	3424
	A. Lüdeke, Å. Andersson, M. Böge, B. Kalantari, B. Keil, M. Pedrozzi, T. Schilcher, V. Schlott, A. Streun PSI, Villigen
	The Swiss Light Source (SLS) is a 3rd generation synchrotron light source in operation since 2001. The paper will point out the recent activities to enhance machine operation and provides an overview about the new beamlines currently under construction at the SLS.

THPLS067	Vertical Beam Size Control in TLS and TPS	coupling, emittance, quadrupole, betatron	3442
	C.-C. Kuo, H.-P. Chang, J.-R. Chen, P.J. Chou, K.-T. Hsu, G.-H. Luo, H.-J. Tsai, D.-J. Wang, M.-H. Wang NSRRC, Hsinchu A. Chao SLAC, Menlo Park, California W.-T. Weng BNL, Upton, Long Island, New York
	Vertical beam size control is an important issue in the light source operations. The horizontal-vertical betatron coupling and vertical dispersion were measured and corrected to small values in the TLS 1.5 GeV storage ring. Estimated beam sizes are compared with the measured values. By employing an effective transverse damping system, the vertical beam blow-up due to transverse coherent instabilities such as the fast-ion beam instability was suppressed and as a result, the light source is very stable. In NSRRC we are designing an ultra low emittance 3-GeV storage ring and its designed vertical beam size could be as small as a few microns. The ground and mechanic vibration effects, and coherent instabilities could spoil the expected photon brightness due to blow-up of the vertical beam size if not well taken care of. The contributions of these effects to vertical beam size increase will be evaluated and the counter measures to minimize them will be proposed and reported in this paper.

THPLS114	"CAMSHAFT" Bunch Kicker Design for the ALS Storage Ring	kicker, storage-ring, vacuum, pick-up	3547
	S. Kwiatkowski, K.M. Baptiste, W. Barry, J. Julian, L. Low, D.W. Plate, G.J. Portmann, D. Robin LBNL, Berkeley, California
	ALS is a 1.9 GeV third generation synchrotron light source that has been operating since 1992 at Lawrence Berkeley National Laboratory. There are two typical modes of operation of the ALS storage ring. In multibunch mode, the ring is filled to a current of 400 mA in 276 consecutive bunches with a single "camshaft" bunch located in the middle of the 52 bucket gap (h=328). Twice each year, ALS operates in "two-bunch" mode for periods of two weeks delivering 20 mA of average beam current in two diametrically opposite bunches to a small group of users requiring light pulses at lower rates. We plan to build a fast kicker system that will supply single bunch light to users during multibunch operation by displacing the orbit of the camshaft bunch at a prescribed frequency (every N turns). Realization of this project will increase ALS beam availability to multibunch users by at least 10%. This paper will describe the hardware design (pulse generator and beam deflection device) and the test results of the prototype kicker unit.

THPLS138	Fast Polarization Switching at the SLS Microspectroscopy Beamline POLLUX	SLS, coupling, dipole, polarization	3610
	M. Böge, U. Flechsig, J. Raabe, T. Schilcher PSI, Villigen
	POLLUX is a new microspectroscopy facility which will be operated at a bending magnet at the Swiss Light Source (SLS). It offers spectroscopy with sub-micrometer spatial resolution for polymer science and magnetism. First user operation is scheduled for summer 2006. One of the novel envisaged options of the beamline is the usage of circular polarized light. The circular polarization will be generated by a localized angular steering of the electron beam within the bending magnet. This is accomplished by means of the global fast orbit feedback system of the SLS which allows to stabilize the electron beam to the sub-micrometer level up to frequencies of ~100 Hz. Due to the adapting coupling compensation involving dedicated adjacent skew quadrupoles, this steering becomes practically transparent to the other beamlines. Polarization switching rates of a few Hz are within reach.