• L. S. Cardman
  
• L. Harwood
  Jefferson Lab, Newport News, Virginia

CEBAF is a 5-pass, recirculating cw electron linac operating at ~6 GeV. The 12-GeV Upgrade is a $300M project anticipated to receive Critical Decision 2 approval in late summer of 2007 and begin construction activities in 2008; funding for the project is provided by the DOE Office of Nuclear Physics which will double the beam energy. The new energy reach will permit significant extensions in research into non-perturbative aspects of QCD. Areas of interest are Generalized Parton Distributions (GPDs), measurements at high-xBjorken, and the use of hybrid mesons to explore the nature of quark confinement. The upgrade includes: doubling the accelerating voltages of the linacs by adding 10 new high-performance cryomodules plus the requisite expansion of the 2K cryogenics plant and rf power systems, upgrading the beam transport system from 6 GeV to 12 GeV capability through extensive re-use of existing hardware, adding one recirculation arc, adding a new experimental area and the beamline to it, building new experimental equipment for the GPD, high-xBjorken, and hybrid mesons programs. The presentation will touch on the science and give some details of the accelerator plans.

• D. F. Sutter
  
• B. P. Strauss
  HENP, SW Washington

• G. Neil
  

• C. Rodrigues
  
• A. R. Silva
  LNLS, Campinas

• C. Rodrigues
  
• L. H. Oliveira, A. R. Silva
  LNLS, Campinas

• P. F. Tavares
  
• N. P. Abreu, J. F. Citadini, R. H.A. Farias, M. J. Ferreira, J. G.R. S. Franco, L. C. Jahnel, L. Liu, A. F.A. G. Moreira, X. R. Resende, G. Tosin
  LNLS, Campinas

• L. Hagge
  
• J. Buerger, J. A. Dammann, S. Eucker, A. Herz, J. Kreutzkamp, S. Panto, D. Szepielak, P. Tumidajewicz, N. Welle
  DESY, Hamburg

• V. V. Katalev
  
• S. Choroba
  DESY, Hamburg

• F. Ludwig
  
• B. Lorbeer, H. Schlarb, A. Winter
  DESY, Hamburg

The next generation of FEL's (Free Electron Lasers) require a long and short term stable synchronisation of RF reference signals with an accuracy of 10 fs. For that an optical synchronisation system is developed for FLASH at DESY, that is based on optical pulse train which carry the timing information encoded in its precise repetition rate. The optical pulse train has to be converted into an RF signal to provide a local reference for calibration and operation of RF based devices. The drift and jitter performance of the optical to RF converter influences directly the phase stability of the accelerator. Three different methods for optical to RF converters, namely the direct photodiode detection, injection locking and a sagnac loop interferometer are currently under investigation. In this paper we concentrate on the jitter and drift performance of the direct photodiode conversion and show its limitations from measurement results.

• M. G. Hoffmann
  
• S. Choroba, F. Eints, U. Hurdelbrink, P. Morozov, Y. Nechaev, J. Randhahn, S. Ruzin, S. Simrock, V. Soloviev
  DESY, Hamburg

• S. Simrock
  
• K. C. Czuba
  Warsaw University of Technology, Institute of Electronic Systems, Warsaw
• M. F. Felber, M. Hoffmann, B. Lorbeer, F. Ludwig, H. C. Weddig
  DESY, Hamburg

• A. Winter
  
• W. J. Jalmuzna
  Warsaw University of Technology, Institute of Electronic Systems, Warsaw
• F. Loehl, H. Schlarb, P. Schmuser
  DESY, Hamburg

• M. Lonza
  
• D. Bulfone, V. Forchi', G. Gaio
  ELETTRA, Basovizza, Trieste

• A. Bonucci
  
• A. Conte, P. Manini, S. Raimondi
  SAES Getters S.p. A., Lainate

• A. Conte
  
• A. Bonucci, P. Manini, S. Raimondi
  SAES Getters S.p. A., Lainate

• H. Harada
  
• K. Furukawa
  KEK, Ibaraki
• H. Hotchi, Y. Irie, F. Noda, H. Sako, H. Suzuki
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• K. Shigaki
  Hiroshima University, Higashi-Hiroshima

• C. K. Allen
  
• H. Ikeda
  Visual Information Center, Inc., Ibaraki-ken
• M. Ikegami
  KEK, Ibaraki
• T. Ohkawa
  JAEA, Ibaraki-ken
• H. Sako, G. B. Shen
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• A. Ueno
  JAEA/LINAC, Ibaraki-ken

The XAL application development environment has been installed as a part of the control system for the Japan Proton Accelerator Research Center (J-PARC). XAL was initially developed at SNS and has been described at length in previous conference proceedings (e.g., Chu et. al. APAC07, Galambos et. al. PAC05, etc.). The fundamental tenet of XAL is to provide a consistent, high-level programming interface, along with a set of high-level application tools, all of which are independent of the underlying machine hardware. Control applications can be built that run at any accelerator site where XAL is installed. Of course each site typically has specific needs not supported by XAL and the framework was designed with this in mind: each institution can upgrade XAL which then is accessible to all users. We outline the upgrades and enhancements to the XAL online model necessary for accurate simulation of the J-PARC linac. For example, we have added permanent magnet quadrupoles and additional space charge capabilities such as off-centered and rotated beams and bending magnets with space charge. We present the physics models for the upgrades as well as the software architecture supporting them.

• H. Ohgaki
  
• T. Kii, K. Masuda, T. Yamazaki, K. Yoshikawa, H. Zen
  Kyoto IAE, Kyoto

• H. Sako
  
• C. K. Allen
  KEK, Ibaraki
• H. Ikeda
  Visual Information Center, Inc., Ibaraki-ken
• G. B. Shen
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

• K. Zheng
  
• Y. B. Chen, L. J. Huang, W. Li, L. Liu, B. Sun, J. H. Wang, L. Wang, Y. L. Yang, Z. R. Zhou
  USTC/NSRL, Hefei, Anhui

In this paper, HLS (Hefei light Source) bunch-by-bunch measurement and feedback system will be introduced. This system is integrated with longitudinal oscillation measurement system, fast vector control, fiber notch filter and bunch current detection system. The detail of the two fronts will be shown. Some experimental results by this system are also present in this paper, as phase-space tracing, mode dumping rate, and feedback experiments.

• Y. Q. Xiong
  
• M. Fan, B. Qin, M. J. Wu, J. Yang
  HUST, Wuhan

A virtual control system designed to control and monitor the process of a cyclotron virtual prototyping is presented in this paper. Based on the feature of cyclotron, a distributed control structure is proposed according to the knowledge of software engineering. LabVIEW is employed to develop human machine interface(HMI), sequential control, safety interlock, and MATLAB is used to implement analysis and simulation. Dynamic data exchange (DDE) supported by Win32 Platform SDK is adopted to process data exchanging by a Server/Client mode. Any additional functions can be extended easily in this system in future.

• I.-S. Hong
  
• Y.-G. Song
  KAERI, Daejon

20MeV proton linear accelerator of the PEFP(Proton Engineering Frontier Project) has above 10 magnet power supplies and getter pumps to interface with Modbus protocol. VME IOC(Input Output Controller) has been designed and constructed for the control system by using VME serial I/O. The driver support module of the VME IOC has been developed to initialize the IO board and communicate with the instruments through EPICS. Operating console and storage module for operators in the control room has been programmed on PC and SUN of the operator interface.

• Y.-G. Song
  
• Y.-S. Cho, I.-S. Hong
  KAERI, Daejon

Proton Engineering Frontier Project (PEFP) has above 40 magnet power supplies for the 20MeV proton linac. Because some power supplies have analog interfaces, we chose ATEC (Analog Input To Ethernet Converter) to monitor their output currents and voltage by supporting the protocol conversion function. Software components of the Experimental Physics and Industrial Control System (EPICS) have been ported to a VME single board computer based on a PowerPC microprocessor (MPC7410). This paper presents the software component and processing of analog input values between EPICS on the PowerPC based board and ATEC operating as Server Mode.

• H.-S. Kang
  
• J. Choi, K. M. Ha, E.-H. Lee, W. W. Lee, I. S. Park
  PAL, Pohang, Kyungbuk

• S.-C. Kim
  
• J. Choi, K. M. Ha, J. Y. Huang
  PAL, Pohang, Kyungbuk

At 2006, PLS Linac magnet power supply (MPS) has been upgraded for the stable beam injection and 4th generation light source research. New MPS are developed new compact MPS of 16-bit resolution and 20ppm stability using four-quadrant switching scheme with 50kHz MOSFET switching device, and consists of main power board, control power board, regulator board and CPU board. Size of each board is only 100mm width and 240mm depth. Output of MPS is 10V, ±10A for the bipolar and 50V, 50A for the unipolar magnet. Main board is consisted four-quadrant FET switch, driver and output filter. Output filter must be perfectly eliminating switch frequency and compact size. In this paper, we report on development and characteristics of compact output filter of the new MPS for PAL linac.

• J. Dedic
  
• D. Golob, A. Hasanovic, M. Plesko
  Cosylab, Ljubljana

• K. Artoos
  
• S. Bartolome-Jimenez, O. Capatina, J. M. Chevalley, K. Foraz, M. Guinchard, C. Hauviller, K. Kershaw, S. Prodon, I. Ruehl, G. Trinquart, S. Weisz
  CERN, Geneva
• P. Ponsot
  DBS, Saint Genis-Pouilly

• F. Caspers
  
• T. Kroyer, J.-P. G. Tock, L. R. Williams
  CERN, Geneva
• J. Kulka
  AGH, Cracow

• G. Fernqvist
  
• M. C. Bastos, A. Cantone, Q. King
  CERN, Geneva

• G. Fernqvist
  
• P. Dreesen, G. Hudson
  CERN, Geneva
• J. R. Pickering
  Metron, Norwich

• G. Fernqvist
  
• M. C. Bastos, A. Cantone, P. Dreesen, O. Fournier, G. Hudson
  CERN, Geneva

• R. J. Steinhagen
  
• A. Boccardi, M. Gasior, O. R. Jones, K. K. Kasinski
  CERN, Geneva

• K. Kershaw
  
• F. Chapron, A. Y. Coin, F. Delsaux, T. Feniet, J. L. Grenard, R. V. Valbuena
  CERN, Geneva

• D. P. Missiaen
  
• P. Bestmann, M. C.L. Buzio, S. D. Fartoukh, M. Giovannozzi, J. B. Jeanneret, A. M. Lombardi, Y. Papaphilippou, S. Pauletta, J. C. Perez, H. Prin, E. Y. Wildner
  CERN, Geneva

• A. Poncet
  
• P. Cruikshank, V. Parma, P. M. Strubin, J.-P. G. Tock, D. Tommasini
  CERN, Geneva

• S. Redaelli
  
• R. W. Assmann, P. Gander, M. Jonker, M. Lamont, R. Losito, A. Masi, M. Sobczak
  CERN, Geneva

• Y. Thurel
  
• B. Favre, D. Nisbet
  CERN, Geneva

• E. Y. Wildner
  
• M. Bajko, P. Bestmann, S. D. Fartoukh, J. B. Jeanneret, D. P. Missiaen, D. Tommasini
  CERN, Geneva

• E. Y. Wildner
  
• N. Emelianenko
  CERN, Geneva

• J.-C. Chang
  
• M. Ke
  NTUT, Taipei
• Z.-D. Tsai
  NSRRC, Hsinchu

• Y.-C. Chien
  
• K. H. Hu, K.-B. Liu, H. M. Shih
  NSRRC, Hsinchu

• K. T. Hsu
  
• J. Chen, P. C. Chiu, S. Y. Hsu, K. H. Hu, C. H. Kuo, D. Lee
  NSRRC, Hsinchu

• C.-Y. Liu
  
• K.-B. Liu, H. M. Shih
  NSRRC, Hsinchu

• Z.-D. Tsai
  
• J.-C. Chang, T.-S. Ueng
  NSRRC, Hsinchu

• H. H. Tsai
  
• S.-H. Chang, W.-S. Chiou, F. Z. Hsiao, H. C. Li
  NSRRC, Hsinchu

• T.-S. Ueng
  
• J.-C. Chang, Z.-D. Tsai
  NSRRC, Hsinchu

• C. Y. Wu
  
• J. Chen, K. T. Hsu, S. Y. Hsu, J.-Y. Hwang, D. Lee, K.-K. Lin, C.-J. Wang
  NSRRC, Hsinchu

• A. Daly
  
• C. W. Appelbee, D. Bayley
  STFC/RAL/ISIS, Chilton, Didcot, Oxon

• M. C. Hughes
  
• J. W. Gray
  STFC/RAL/ISIS, Chilton, Didcot, Oxon

* M. G. White et al., A 3-BeV High Intensity Proton Synchrotron, The Princeton-Pennsylvania Accelerator, CERN Symp.1956 Proc., p525.

• A. Bosco
  
• G. A. Blair, S. T. Boogert, G. E. Boorman
  Royal Holloway, University of London, Surrey

Electro-optic techniques might allow implementing a laserwire scanner for intra-train scanning at the ILC with scanning speed in excess of 100 kHz. A scanner capable of running at such a rate would in fact provide information about the particle beam size in about one hundred different positions along the bunch train (approximately 1ms long for the ILC*). The design of an electro-optic deflector capable to scan within 10-100 microsecond is presented, discussed and analytically treated.

* ILC Baseline Conceptual Design (2006).: http://www.linearcollider.org/.

• S. Cohen
  
• M. W. Sherman, W. D. Sherman
  Alpha Scientific Electronics, Hayward, CA

• S. Cohen
  
• S. R. Babel
  Bira, Albuquerque, New Mexico

• N. P. Di Monte
  

The P0 Feedback System is a new design at the APS with the main intent to stabilize a single bunch in order to operate at a higher accumulated charge. The algorithm for this project required a high-speed DSP solution for a single channel that would make adjustments on a turn-by-turn basis. An FPGA solution was selected that not only met the requirements of the project, but far exceeded the requirements. By using a single FPGA, we were able to adjust up to 324 bunches on two separate channels with a total computational time of ~6x10⁹ multiply-accumulate operations per second. The IOC is a Coldfire CPU tightly coupled to the FPGA, providing a dedicated control and monitoring of the system through EPICS process variables. One of the benefits of this configuration is having a four-channel scope in the FPGA that can be monitored on a continuous basis.

• G. Feng
  
• B. Deriy, J. Wang
  ANL, Argonne, Illinois

Due to the circuit topology of ramping power supplies used in the APS Booster ring, they are unable to follow the linear current ramp to the desired accuracy of 0.1%. In addition, those supplies are also sensitive to AC line perturbation. To improve the performance, a linear regulator using paralleled MOSFET devices in series with the power supply is proposed. The control algorithm uses a real-time current feedback loop to force the MOSFETs to work in the linear operation mode. By using this linear MOSFET regulator, the MOSFETs' drain to source voltage, and hence the voltage imposed on magnets can be regulated very quickly. As a result, the regulation of the magnet current can be improved significantly. So far the simulation results show that with the linear regulator the current regulation can be improved to better than 0.1%. Because of the high bandwidth of the linear regulator, it can reduce the harmonic content in the output current as well as the noises due to the AC line disturbance. A sextupole power supply has been set up to verify the proposed topology. This paper discusses the circuit topology, the regulation algorithm, and the experiment results.

• C. C. Drennan
  
• M. Ball, A. R. Franck, D. J. Harding, P. A. Kasley, G. E. Krafczyk, M. J. Kucera, J. R. Lackey, D. McArthur, J. R. Misek, W. Pellico, E. Prebys, A. K. Triplett, D. Wolff
  Fermilab, Batavia, Illinois

To better control the beam position, tune, and chromaticity in the Fermilab Booster synchrotron, a new package of six corrector elements has been designed, incorporating both normal and skew orientations of dipole, quadrupole, and sextupole magnets. The devices are under construction and will be installation in 48 locations in the Booster accelerator. Each of these 288 corrector magnets will be individually powered. Each of the magnets will be individually controlled using operator programmed current ramps designed specifically for the each type of Booster acceleration cycle. This paper provides an overview of the corrector magnet installation in the accelerator enclosure, power and sensor interconnections, specifications for the switch-mode power supplies, rack and equipment layouts, controls and interlock electronics, and the features of the operator interface for programming the current ramps and adjusting the timing of the system triggers.

• M. Hu
  
• D. R. Broemmelsiek, B. Chase, J. L. Crisp, N. E. Eddy, P. W. Joireman, K. Y. Ng
  Fermilab, Batavia, Illinois

• E. Prebys
  
• C. C. Drennan, D. J. Harding, V. S. Kashikhin, J. R. Lackey, A. Makarov, W. Pellico
  Fermilab, Batavia, Illinois

The Fermilab neutrino program places unprecedented demands on the lab's 8 GeV Booster synchrotron, which has not changed significantly since it was built almost 35 years ago. In particular, the existing corrector system is not adequate to control beam position and tune throughout the acceleration system, and provides limited compensation for higher order resonances. We present an ambitious ongoing project to build and install a set of 48 corrector packages, each containing horizontal and vertical dipoles, normal and skew quadrupoles, and normal and skew sextupoles. Space limitations in the machine have motivated a unique design, which utilizes custom wound coils around a 12 pole laminated core. Each of the 288 discrete multipole elements in the system will have a dedicated power supply, the output current of which is controlled by an individual programmable ramp. This provides for great flexibility in the system, but also presents a challenge in terms of designing the control hardware and software in such a way that the system can be operated in the most efficacious way.

• J. Ruan
  
• H. Edwards, R. P. Fliller, J. K. Santucci
  Fermilab, Batavia, Illinois

The current Fermilab A0 Photoinjector laser system includes a seed laser, a flashlamp pumped multipass amplifier cavity, a flashlamp pumped 2-pass amplifier system followed by an IR to UV conversion stage. However the current system can only deliver up to 800 pulses due to the low efficiency of Nd:Glass used inside multi-pass cavity. In this paper we will report the effort to develop a new multi pass cavity based on Nd:YLF crystal end-pumped by diode laser. We will also discuss the foreseen design of the laser system for the NML accelerator test facility at Fermilab.

• M. Votava
  
• B. Chase, M. Wendt
  Fermilab, Batavia, Illinois

The major controls and instrumentation systems for the ILC test areas and the NML test accelerator at Fermilab are discussed. The test areas include 3 separate areas for Vertical Superconducting RF Cavity Testing, Horizontal Cavity Testing, and NML RF and beam test area. A common control infrastructure for the test areas including a controls framework, electronic logbook and cavity database will be provided, while supporting components supplied by collaborators with diverse areas of expertise (EPICS, DOOCS, LabVIEW, and Matlab). The discussions on the instrumentation systems are focused on overview and requirements.

• A. V. Zlobin
  
• G. Ambrosio, N. Andreev, E. Barzi, R. Bossert, R. H. Carcagno, G. Chlachidze, J. DiMarco, SF. Feher, V. Kashikhin, V. S. Kashikhin, M. J. Lamm, A. Nobrega, I. Novitski, D. F. Orris, Y. M. Pischalnikov, P. Schlabach, C. Sylvester, M. Tartaglia, J. C. Tompkins, D. Turrioni, G. Velev, R. Yamada
  Fermilab, Batavia, Illinois

Accelerator magnets based on Nb3Sn superconductor advances magnet operation fields above 10T and increases the coil temperature margin. Development of a new accelerator magnet technology includes the demonstration of main magnet parameters (maximum field, quench performance, field quality, etc.) and their reproducibility using short models, and then the demonstration of technology scale up using long coils. Fermilab is working on the development of Nb3Sn accelerator magnets using shell-type dipole coils and react-and-wind method. As a part of the first phase of technology development Fermilab built and tested six 1-m long dipole models and several dipole mirror configurations. The last three dipoles and two mirrors reached their design fields of 10^-11 T. Reproducibility of magnet field quality was demonstrated by all six short models. The technology scale up phase has started by building 2m and 4m dipole coils and testing them in a mirror configuration. This effort complements the Nb3Sn scale up work being performed in the framework of US LHC Accelerator Research Program (LARP). The status and main results of the Nb3Sn accelerator magnet development at Fermilab are reported.

• J. W. Staples
  
• J. M. Byrd, R. B. Wilcox
  LBNL, Berkeley, California

Long-term phase drifts of less than a femtosecond per hour have been demonstrated in a 2 km length of single-mode optical fiber, stabilized interferometrically at 1530 nm. Recent improvements include a wide-band phase detector that reduces the possibility of fringe jumping due to fast external perturbations of the fiber and locking of the master CW laser wavelength to a molecular absorption line. Mode-locked lasers may be synchronized using two wavelengths of the comb, multiplexed over one fiber, each wavelength individually interferometrically stabilized.

• J. M. Weber
  
• M. J. Chin, CA. Timossi, E. C. Williams
  LBNL, Berkeley, California

The emergence of Field Programmable Gate Arrays (FPGAs) with embedded processors and significant progress in their development tools have contributed to the realization of system-on-a-chip networked front-end systems. Embedded processors are capable of running full-fledged Real-Time Operating Systems (RTOSs) and serving channels via Ethernet while high speed hardware functions, such as digital signal processing and high performance interfaces, run simultaneously in the FPGA logic. Despite significant advantages of the system-on-a-chip implementation, engineers have shied away from designing such systems due to the perceived daunting task of integrating software to run a RTOS with custom hardware. However, advances in embedded development tools considerably reduce the effort required for software/hardware integration. This paper will describe the implementation and integration of software and hardware in an FPGA embedded processor system as illustrated by the design of a new control system module for the ALS.

• P. Messmer
  
• J. G. Power
  ANL, Argonne, Illinois
• V. H. Ranjbar, D. J. Wade-Stein
  Tech-X, Boulder, Colorado
• P. Schoessow
  Euclid TechLabs, LLC, Solon, Ohio

Field Programmable Gate Arrays (FPGAs) offer a powerful alternative to ASICs or general purpose processors in accelerator control applications. Software development for these devices can be awkward and time consuming, however, when using low level hardware design languages. To facilitate the use of FPGAs in control systems we are developing a library of software tools based on ImpulseC, a high level subset of the C language specifically designed for FPGA programming. Development and testing of the software will be performed on a Xilinx Virtex-4 FPGA demo board. We will present timing benchmarks for common control functions (PID feedback loops, FIR and Kalman filters) and present plans for the development of a controller for the Argonne Wakefield Accelerator high current photoinjector based on this work.

• C. Wu
  
• E. Abed, G. Bai, B. L. Beaudoin, S. Bernal, I. Haber, R. A. Kishek, P. G. O'Shea, M. Reiser, D. Stratakis, D. F. Sutter, K. Tian, M. Walter
  UMD, College Park, Maryland

Beam based alignment and control has been a critical issue for many accelerators. In this paper, we've developed a new approach that can correct the beam orbit using a systematic quad-scan method, where there is an insufficient number of beam position monitors. In this approach, we've proposed a calibrated response matrix. This matrix takes consideration of the different sensitivities of different quadrupoles in the lattice. With the calibrated response matrix, we can greatly enhance our ability to control the beam centroid motion and reduce the control effort.

• S. M. Hartman
  
• S. F. Mikhailov, V. Popov, Y. K. Wu
  FEL/Duke University, Durham, North Carolina

At Duke University, a booster synchrotron was recently commissioned as part of the HIGS upgrade. For the ramping magnet power supply controls, a scheme was developed to present the high level operator interface in terms of the physics quantities of the accelerator, i.e. the effective focusing strength of the magnets. This scheme allows for the nonlinearities of the magnets – a result of the extremely compact footprint of this booster – to be incorporated into the low level software. This facilitates machine studies and simplifies use of physics modeling. In addition, it simplifies operation, allowing the booster to ramp to any energy from the 0.27 GeV of the injector linac to the 1.2 GeV maximum of the Duke Storage Ring. The high level of flexibility of this system if further advanced by incorporating the level of tunability typically found in a storage ring control system. Tuning changes made during steady-state operation are automatically propagated to the waveforms which make up the booster ramp. This approach provides a good match to the wide operation modes of the Duke Storage Ring and its associated free electron laser, and may useful for other compact booster synchrotrons.

• P. Quigley
  
• S. A. Belomestnykh, M. Liepe, V. Medjidzade, J. Sears, V. Veshcherevich
  CLASSE, Ithaca

Cornell is building a 1.3 GHz Injector Cryomodule for an ERL prototype. The cryomodule consists of five two-cell niobium cavities each cavity having two coaxial power input couplers. Cavity and coupler pairs will require acceptance testing at high power prior to assembly in the injector cryomodule. A liquid nitrogen cryostat for testing the couplers at high power has been built and the first input coupler test is complete. In addition, a Horizontal Test Cryostat (HTC) is being built to test input coupler pairs and cavities as a set. The first HTC test is scheduled for spring 2007. Details for instrumentation of the Coupler Test Cryostat (CTC) and HTC are presented.

• M. J. Borden
  
• C. A. Chapman, C. T. Kelsey, J. F. O'Hara, J. Sturrock
  LANL, Los Alamos, New Mexico

Dose rate modeling and post irradiation measurements of the Isotope Production Facility beamline, at the Los Alamos Neutron Science Center (LANSCE) accelerator, have determined that a radiation shielding shutter is required to protect personnel from shine from irradiated targets for routine beam tunnel entries. This paper will describe radiation dose modeling, shielding calculations and the failsafe mechanical shutter design.

• J. T. Bradley III
  
• C. J. Andrews, L. F. Fernandez, M. F. Fresquez, W. Reass, W. Roybal, J. B. Sandoval
  LANL, Los Alamos, New Mexico

The proton beam in the LANSCE accelerator is guided and focused almost exclusively by electromagnets. Magnet hysteresis has had significant impacts on the tuning of the LANSCE accelerator.* Magnet hysteresis can also have an impact on Magnet Power Supply (MPS) control, regulation and repeatability requirements. To date, MPS performance requirements have been driven by the requirements on the magnetic fields as determined by the accelerator physicists. Taking hysteresis effects into account can significantly change MPS requirements, as some requirements become more stringent and some are found to be overspecified. Overspecification of MPS requirements can result in significant increases in MPS cost. Conversely, the use of appropriate MPS requirements can result in significant cost savings. The LANSCE accelerator's more than three decades of operation provide a wide variety of magnet power supply technologies and operational experience. We will survey the LANSCE magnet power supply history and determine how performance specifications can be refined to both reduce costs and improve the operators abilities to control the magnetic fields.

*R. McCrady, "Mitigation Of Magnet Hysteresis Effects at LANSCE", LINAC 2006, August, 2006.

• M. Pieck
  
• E. Bjorklund, G. P. Carr, J. A. Faucett, J. O. Hill, D. M. Kerstiens, P. S. Marroquin, P. McGhee, M. A. Oothoudt, S. Schaller
  LANL, Los Alamos, New Mexico

• A. Chan
  
• P. Bellomo, G. R. Crane, P. Emma, E. Grunhaus, K. Luchini, I. A. MacGregor, D. S. Marsh, R. Pope, P. L. Prickett, E. Rago, K. Ratcliffe, T. Shab
  SLAC, Menlo Park, California

Changes to beamline optics may effect many engineering processes downstream. In the past, we incorporated these changes manually into disparate engineering spreadsheets. At LCLS, database applications have been developed in order to compare and clearly display differences amongst various versions of beamline optics files. These applications also incorporate the changes into engineering databases, after they have been validated by the engineers. This allows the engineers to be notified, and modifications to be made if beamline optics changes require corresponding adjustments of engineering elements. This paper will describe how this streamlines the workflow, and also provides greater reliability in how beamline optics changes are integrated into engineering databases (such as cabling, power supplies, inventory). The paper includes a description of the related LCLS inventory system, which also serves as a repository for quality assurance documents. The underlying database schemas and applications will be outlined.

• W. Wittmer
  
• W. S. Colocho, G. R. White
  SLAC, Menlo Park, California

The controls software in use at PEP II had originally been developed in the eighties. The functionality and maturity of the applications in that system have made it very successful in routine operation, but this same longevity and orientation toward fixed requirements, make it largely unsuitable for rapid machine development and ad-hoc online experimentation. A successful recent trend at light sources has been to use the so called MATLAB Middle Layer (MML). This package abstracts each underlying control system framework to which it is connected, such as Channel Access. We describe the middle layer implementation for PEP II and LCLS based on AIDA (described elsewhere in these proceedings), which is unusual in that it provides access to the high level functionality of the legacy control system, as well as to a very large assortment of useful data in addition to channel access read and control. The MML had to be adapted for the implementation at PEP II since colliders differ significantly from light sources by scale and symmetry of the lattice, and PEP II is the first collider at which such an implementation is being done.

• B. Lam
  
• P. Bellomo, D. Macnair, A. C. de Lira
  SLAC, Menlo Park, California

In 2008 KEK is commissioning ATF2 - an extension to the existing ATF. ATF2 is a mockup of the final focus test beam accelerator envisioned in the ILC. SLAC is designing the power supply systems for the dc magnets in the ATF2, which will require 38 power supplies ranging from 1.5 to 6 kW, currents from 50 to 200 A, all rated at output voltages not higher than 30 V. Because of the extensive quantities of magnets required for the ILC, high availability is paramount to its successful operation, so the power supply topology chosen for the ATF2 uses N+1 redundancy, with 50-A power modules to construct each power supply. These power modules are current-mode buck regulators, which operate in parallel with each other and one redundant module. One bulk power supply provides off-the-line regulated dc input to a number of the power supplies. Current stability requirements for the magnets range from 10 to 10⁰⁰ ppm. A precision current transductor and a recently developed SLAC-built 20-bit Ethernet Power Supply Controller will provide the current regulation required. In this paper we present the conceptual design, prototype results, and the status of the power supply systems for the ATF2.

• C. H. Rivetta
  
• R. Akre, P. Cutino, J. C. Frisch, K. D. Kotturi
  SLAC, Menlo Park, California

The LCLC RF gun requires a water cooling thermal system to tune the resonance frequency of the cavity to 2856.03MHz. The RF system operates in pulsed mode with bursts of 2.5usec at a repetition rate of 30-120Hz. The thermal system operates in combination with the low-level RF system to set the operation point of the cavity. The Low-Level RF system controls the magnitude and phase of the cavity voltage and define slow signals to the thermal system. The thermal system operates by pre-heating / pre-cooling the water and mixing both channels to achieve the optimal temperature to control the cavity resonant frequency. The tune control of the RF gun include two systems with different dynamics. The dynamics of the thermal system is slow while the RF system is fast. Additionally, different actuators in the system present limits that introduce non-linearities to be taking into account during the start up process . Combining these characteristics, a controller is designed for the resulting hybrid system that allows convergence in large for all the operation conditions and achieve the performance in the magnitude and phase of the cavity voltage required around the operation point.

• J. E. Spencer
  
• S. D. Anderson, Z. R. Wolf
  SLAC, Menlo Park, California
• M. Boussoufi
  UCD/MNRC, McClellan, California
• G. Gallagher, D. E. Pellet
  UCD, Davis, California
• J. T. Volk
  Fermilab, Batavia, Illinois

Many materials and electronics need to be tested for the radiation environment expected at linear colliders (LC) to improve reliability and longevity since both accelerator and detectors will be subjected to large fluences of hadrons, leptons and gammas. Examples include NdFeB magnets, considered for the damping rings, injection and extraction lines and final focus, electronic and electro-optic devices to be utilized in detector readout, accelerator controls and the CCDs required for the vertex detector, as well as high and low temperature superconducting materials (LTSMs) because some magnets will be superconducting. Our first measurements of fast neutron, stepped doses at the UC Davis McClellan Nuclear Reactor Center (UCD MNRC) were presented for NdFeB materials at EPAC04 where the damage appeared proportional to the distances between the effective operating point and Hc. We have extended those doses, included other manufacturer's samples and measured induced radioactivities. We have also added L and HTSMs as well as a variety of relevant semiconductor and electro-optic materials including PBG fiber that we studied previously only with gamma rays.

• A. C. de Lira
  
• P. Bellomo, K. Luchini, D. Macnair
  SLAC, Menlo Park, California

The LCLS injector at SLAC requires 100+ dc-magnet power supply systems for its operation. Power supplies are divided into two main groups: intermediate rack-mounted type for output powers up to 20 kW at 375 A, and bipolar units rated 6 A, 12 A, and 30 A for corrector magnets and small quadrupoles. The intermediate power supplies are controlled by a 20-bit Ethernet power supply controller, specially developed at SLAC to be used in this project. The bipolar units are controlled via 12-bit DACs and ADCs housed in a VME crate. EPICS is the controls interface to all systems. For all systems, stability requirements are better than 10⁰⁰ ppm. The Power Conversion Department at SLAC, in close cooperation with the LCLS Controls group, was responsible for defining the major characteristics of the power supply systems, their specification, procurement, installation, and commissioning. In this paper we describe the main characteristics of the power supply systems for the LCLS injector, including results from their successful commissioning early this year.

• L. Bees
  
• L. Simpson, A. Tydeman
  Lambda, Neptune, New Jersey

• V. P. Yakovlev
  
• J. L. Hirshfield
  Omega-P, Inc., New Haven, Connecticut
• A. Kanareykin
  Euclid TechLabs, LLC, Solon, Ohio
• S. Kazakov
  KEK, Ibaraki
• E. Nenasheva
  Ceramics Ltd., St. Petersburg
• S. V. Shchelkunov
  Columbia University, New York

Fast, electrically-controlled ferroelectric RF vector modulators are under development for different accelerator applications in the frequency range 0.4 - 1.3 GHz. The exact design of a vector modulator depends on the electrical parameters of particular ferroelectric material to be used, namely its dielectric constant, loss tangent and tunability. The exact values of these parameters were unknown in this frequency domain for low loss BST material that is planned to be used. A special two-disc test cavity has been designed and built that allows direct measurements of these parameters for large (100 mm in diameter) ferroelectric rings that are to be used in vector modulators. The results of measurements are presented.

• V. P. Yakovlev
  
• J. L. Hirshfield
  Omega-P, Inc., New Haven, Connecticut
• A. Kanareykin
  Euclid TechLabs, LLC, Solon, Ohio
• S. Kazakov
  KEK, Ibaraki
• E. Nenasheva
  Ceramics Ltd., St. Petersburg

A fast, electrically-controlled phase shifter is described with parameters suitable for operation with the SC acceleration structure of the electron cooling system of Relativistic Heavy Ion Collider (RHIC) at BNL. The phase shifter is a key element of the external RF vector modulator that is capable of fast tuning of the cavities against microphonics, Lorentz force and beam instabilities in a way that can possibly lead to an order of magnitude reduction in the required RF power. The phase shifter is based on a shortened low-impendence coaxial line with ferroelectric rings. The dielectric constant of the ferroelectric rings is altered by applying a 4.2 kV voltage that provides an RF phase shift from 0 to 180 deg.

• G. H. Biallas
  
• N. T. Belcher
  The College of William and Mary, Williamsburg
• D. Douglas, T. Hiatt, K. Jordan
  Jefferson Lab, Newport News, Virginia

Two styles of Panofsky Quadrupoles with integral corrector dipole windings are in use in the electron beam line of the Free Electron Laser at Jefferson Lab. We combined the functions into single magnets, adding hundreds of Gauss-cm dipole corrector capability to existing quadrupoles because space is at a premium along the beam line. Superposing high quality dipole corrector field on a high quality, weak (600 to 1'000 Gauss) quadrupole is possible because the parallel slab iron yoke of the Panofsky Quadrupole acts as a window frame style dipole yoke. The dipole field is formed when two current sources, designed and made at Jlab, add and subtract current from the two opposite quadrupole current sheet windings parallel to the dipole field direction. The current sources also drive auxiliary coils at the yoke's inner corners that improve the dipole field. Magnet measurements yielded the control system field maps that characterize the two types of fields. Details of field analysis using OPERA, construction methods, wiring details, magnet measurements and the current sources are presented.

• J. Musson
  
• J. M. Grames, J. Hansknecht, R. Kazimi, M. Poelker
  Jefferson Lab, Newport News, Virginia

Recent upgrades to the CEBAF Polarized Source include a fiber-based seed laser, capable of producing pulses with frequency centered at 499 MHz. Combined with the existing three-beam Chopper, an aliasing, or beat frequency technique is used to produce long time intervals between individual electron microbunches (tens of nanoseconds) by merely varying the nominal 499 MHz drive laser frequency by <20%. This RF Laser modulator uses a divider and heterodyne scheme to maintain coherence with the accelerator Master Oscillator, while providing delay resolution in increments of 2ns. Laser repetition frequencies producing bunch repetition rates between 20 MHz and 100 MHz are demonstrated, resulting in time delays between 50 and 10 ns, respectively. Also, possible uses for such a beam are discussed as well as intended development. Authored by Jefferson Science Associates, LLC under U. S. DOE Contract No. DE-AC05-06OR23177

• H. Ma
  
• M. S. Champion, M. T. Crofford, T. W. Hardek, K.-U. Kasemir, M. F. Piller, Y. Zhang
  ORNL, Oak Ridge, Tennessee

The proposed upgrade plan for RF control of the Spallation Neutron Source (SNS) accumulator ring requires that the new digital field control module (FCM) support both the conventional narrow-band feed forward control and a new beam-based feed forward control. Both are necessary for compensating the heavy beam loading in SNS ring. The ring FCM also has the integrated control and monitoring features for the cavity bias, cavity resonance, and tetrode grid boost. A user-friendly Epics GUI for all these FCM functionalities is also a part of the requirement. The ring FCM under development is being implemented on the hardware of the proven FCM of SNS Linac. Both the controller architecture and the design code of the digital hardware for the Linac system will be largely reused in the ring system.

• M. P. McCarthy
  
• D. E. Anderson, I. E. Campisi, F. Casagrande, R. I. Cutler, G. W. Dodson, J. Galambos, D. P. Gurd, Y. W. Kang, K.-U. Kasemir, S.-H. Kim, H. Ma, B. W. Riemer, J. P. Schubert, M. P. Stockli
  ORNL, Oak Ridge, Tennessee

Increasing the pulse repetition rate (PRR) of the SNS Linac to its designed maximum of 60 Hz to provide 1.4 MW of beam on target is in progress. Operation above 60 Hz in the future to provide beam to a second target is also being considered. Increasing the PRR to 80 Hz would allow the additional pulses to be diverted to a second target. This paper discusses the impact of increasing the PRR on the SNS infrastructure including Radio Frequency (RF) systems and structures, the ion source, cryogenics, controls and the target.

• A. K. Polisetti
  
• S. Assadi, C. Deibele, J. C. Patterson
  ORNL, Oak Ridge, Tennessee
• R. C. McCrady
  LANL, Los Alamos, New Mexico
• M. J. Schulte
  UW-Madison, Madison, Wisconsin

• D. Stout
  
• S. Assadi, I. E. Campisi, F. Casagrande, M. T. Crofford, W. R. DeVan, X. Geng, T. W. Hardek, S. Henderson, M. P. Howell, Y. W. Kang, W. C. Stone, W. H. Strong, D. C. Williams, P. A. Wright
  ORNL, Oak Ridge, Tennessee

The SNS project was completed with only limited SRF facilities installed as part of the project, namely a 5 MW, 805 MHz RF test stand, a fundamental power coupler processing system, a concrete test cave shell, and temporary cleaning/assembly facilities. A concerted effort has been initiated to install the infrastructure and equipment necessary to maintain and repair the superconducting Linac, and to support power upgrade R&D. Installation of a Class10/100/10,000 cleanroom and outfitting of the test cave with RF, vacuum, controls, personnel protection and cryogenics systems is underway. A horizontal cryostat, which can house a helium vessel/cavity and fundamental power coupler for full power, pulsed testing, is being procured. Equipment for cryomodule assembly/disassembly and cavity processing also is being designed. This effort, while derived from the experience of the SRF community, will provide a unique high power test capability as well as long term maintenance capabilities. This paper presents the current status and the future plans for the SNS SRF facilities.

• D. C. Williams
  
• X. Geng, P. Ladd
  ORNL, Oak Ridge, Tennessee

The superconducting linac of the Spallation Neutron Source (SNS) has 23 cryomodules each of which incorporate either 3 or 4 niobium cavities. These cavities are submerged in a bath of liquid helium and maintained at an operating temperature of ~ 2K. This bath is surrounded by heat shields and a multilayer blanket within the cryomodule shell. The pressure in this area needs to be maintained at <5·10^-5 torr to limit heat leak due to gas convection. Some cryomodules have developed helium leaks into this vacuum cavity and now need to be actively pumped. This paper provides an overview of the Insulating Vacuum System (IVS) that has been installed for this purpose.

• A. Grassellino
  
• J. K. Keung, F. M. Newcomer
  University of Pennsylvania, Philadelphia, Pennsylvania
• N. Lockyer
  TRIUMF, Vancouver

• A. Kanareykin
  
• A. Dedyk
  Eltech University, St. Petersburg
• E. Nenasheva
  Ceramics Ltd., St. Petersburg
• V. P. Yakovlev
  Omega-P, Inc., New Haven, Connecticut

We present recent results on development of a BST(M) ferroelectric composition synthesized for use in advanced technology components for X-band and Ka-band RF systems in high gradient accelerators and offer significant advantages for high power RF manipulation in the 300-1'000 MHz frequency range as well. These low loss ferroelectric materials can be used as key elements of both tuning and phase shifting components. We have identified BST ferroelectric-oxide compounds as suitable materials for a fast electrically-controlled 700 MHz, 50 kW tuner for ERL (BNL) and for high-power fast RF phase shifters to be used for SNS vector modulation applications. We have also developed large diameter (11 cm) BST(M)-based ferroelectric rings planned to be used at high average power (10 kW range) for L-band phase-shifters intended for the ILC. This phase shifter will allow coupling adjustment and control of the power consumption during the process of SC cavity filling.

• D. Bruno
  
• G. Ganetis, W. Louie, J. Sandberg
  BNL, Upton, Long Island, New York

The two rings in the Relativistic Heavy Ion Collider (RHIC) were originally constructed with 24 sextupole power supplies, 12 for each ring. Before the start of Run 7, 24 new sextupole power supplies were installed, 12 for each ring. Individual sextupole power supplies are now each connected to six sextupole magnets. A superconducting snake magnet and power supplies were installed in the Alternating Gradient Synchrotron (AGS) and commissioned during RHIC Run 5, and used operationally in RHIC Run 6. The power supply technology, connections, control systems and interfacing with the Quench Protection system for both these systems will be presented.

• D. Bruno
  
• G. Ganetis, G. Heppner, W. Louie, J. Sandberg, C. Schultheiss
  BNL, Upton, Long Island, New York

The two rings in the Relativistic Heavy Ion Collider (RHIC) require a total of 933 power supplies to supply current to highly inductive superconducting magnets. Failure statistics for the RHIC power supplies will be presented for the last three RHIC runs. The failures of the power supplies will be analyzed. The statistics associated with the power supply failures will be presented. Comparisons of the failure statistics for the last three RHIC runs will be shown. Improvements that have increased power supply availability will be discussed. Further improvements to increase the availability of the power supplies will also be discussed.

• I. Marneris
  
• S. V. Badea, R. Bonati, T. Roser, J. Sandberg
  BNL, Upton, Long Island, New York

The Brookhaven AGS Main Magnet Power Supply (MMPS) is a thyristor control supply rated at 5500 Amps, ±9000 Volts. The peak magnet power is 50 MWatts. The power supply is fed from a motor/generator manufactured by Siemens. The generator is 3 phase 7500 Volts rated at 50 MVA. The peak power requirements come from the stored energy in the rotor of the motor/generator. The motor generator is about 45 years old and Siemens is not manufacturing similar machines in the future. We are therefore investigating different ways of storing energy for future AGS MMPS operation. This paper will present simulations of a power supply where energy is stored in capacitor banks. Two dc to dc converters will be presented. The switching elements would be IGCT's made by ABB. The simulation program used is called PSIM Version 6.1. The control system of the power supply will also be presented. The average power from the Long Island Power Authority (LIPA) into the power supply will be kept constant during the pulsing of the magnets at ±50 MW. The reactive power will also be kept constant below 1.5 MVAR. Waveforms will be presented.

• J. Niedziela
  
• W. Fu, M. Harvey, G. J. Marr, T. Satogata, V. Schoefer
  BNL, Upton, Long Island, New York

Centralization of information pertaining to accelerators can benefit accelerator operation and development. Further, retention and the changeable nature of information present challenges to accelerator operation, particularly in instances of turnover. MediaWiki is free, server-based software licensed under the GNU General Public License that uses PHP to render data stored in a MySQL database as interactive web documents, and is designed to produce collaborative documentation. The MediaWiki engine was implemented at BNL, and this paper describes the first year of use by the Operations, Controls, and RF groups at the Collider-Accelerator Department, including code modifications, common practices, and the use of the wiki as a training tool.

• I. Pinayev
  

• Y.-C. Chao
  

• R. A. Kishek
  
• G. Bai, B. L. Beaudoin, S. Bernal, D. W. Feldman, R. Feldman, R. B. Fiorito, T. F. Godlove, I. Haber, T. Langford, P. G. O'Shea, C. Papadopoulos, B. Quinn, M. Reiser, D. Stratakis, D. F. Sutter, J. C.T. Thangaraj, K. Tian, M. Walter, C. Wu
  UMD, College Park, Maryland

Circular accelerators and storage rings have traditionally been designed with limited intensity in order to avoid resonances and instabilities. The possibility of operating a ring beyond the Laslett tune shift limit has been suggested but little tested, apart from a pioneering experiment by Maschke at the BNL AGS in the early 1980s. We have recently circulated the highest-space-charge beam in a ring to date in the University of Maryland Electron Ring (UMER), achieving a breakthrough both in the number of turns and in the amount of current propagated. At undepressed tunes of up to 7.6, the space charge in UMER is sufficient to depress the tune by nearly a factor of 2, resulting in tune shifts up to 3.6. This makes the UMER beam the most intense beam that has been propagated to date in a circular lattice. This is an exciting and promising result for future circular accelerators, and the UMER beam can now be used as a platform to study intense space charge dynamics in rings.

• K. Takayama
  

* K. Takayama, published in Phys. Rev. Lett. soon.** K. Takayama and J. Kishiro, N. I.M. A 451, 304-317 (2000).*** K. Takayama, K. Torikai, Y. Shimosaki, and Y. Arakida, PCT/JP2006/308502

• S. Choroba
  

• G. Leyh
  

Construction of the ILC 'Reference Design' Marx Modulator is complete, and testing is currently underway at SLAC. The Reference Design prototype is oil-free, air-cooled, and capable of delivering 120kV, 140A pulses at a rate of 5Hz. Total energy per pulse is 23,500 joules. Projected efficiency is greater than 96%. The Reference Design Marx modulator employs a stack of 12kV Marx modules that generate high-voltage output pulses directly from a 12kV input supply voltage. This direct switching eliminates the requirement for a massive transformer and reduces the capacitor bank size by more than a factor of four, yielding a considerably cheaper and more compact mechanical solution. Advantages of the Marx design include higher efficiency, smaller physical size, and a modular architecture that provides greater reliability and cost-effective PC board-level integration. This paper outlines the ILC Marx Modulator Development Program currently underway at SLAC. The paper presents detailed mechanical and electrical design diagrams, 3D field simulations, and operational test results for the full-scale Reference Design modulator prototype.

• R. L. Cassel
  
• S. Hitchcock
  Stangenes Industries, Palo Alto, California

• J. Carwardine
  
• N. D. Arnold, F. Lenkszus, C. W. Saunders
  ANL, Argonne, Illinois
• B. Banerjee, B. Chase, E. G. Gottschalk, P. W. Joireman, P. A. Kasley, J. R. Lackey, P. M. McBride, J. F. Patrick, V. Pavlicek, M. Votava, S. A. Wolbers
  Fermilab, Batavia, Illinois
• R. W. Downing, R. S. Larsen
  SLAC, Menlo Park, California
• K. Furukawa, S. Michizono
  KEK, Ibaraki
• K. Rehlich, S. Simrock
  DESY, Hamburg

The scale and performance parameters of the ILC require new thinking in regards to control system design. This design work has begun quite early in comparison to most accelerator projects, with the goal of uniquely high overall accelerator availability. Among the design challenges are high control system availability, timing reference distribution, standardization of interfaces, operability, and maintainability. We present the current state of the design and take a prospective look at ongoing research and development projects.

• K. Furukawa
  

• P. Cameron
  
• J. Cupolo, W. C. Dawson, C. Degen, A. Della Penna, L. T. Hoff, Y. Luo, A. Marusic, R. Schroeder, C. Schultheiss, S. Tepikian
  BNL, Upton, Long Island, New York
• M. Gasior
  CERN, Geneva

Tune feedback was first implemented in RHIC in 2002 as a specialist activity. The transition to full operational status was impeded by dynamic range problems, as well as by overall loop instabilities driven by large coupling. The dynamic range problem was solved by the CERN development of the Direct Diode Detection Analog Front End. Continuous measurement of all projections of the betatron Eigenmodes made possible the world's first implementation of coupling feedback during beam acceleration, resolving the problem of overall loop instabilites. Simultaneous tune and coupling feedbacks were utilized as specialist activities for ramp development during the 2006 RHIC run. At the beginning of the 2007 RHIC run there remained two obstacles to making these feedbacks fully operational in RHIC - chromaticity measurement and control, and the presence of strong harmonics of the power line frequency in the betatron spectrum. We report here on progress in tune, coupling, and chromaticity measurement and feedback, and discuss the relevance of our results to the LHC commissioning effort. The results of investigations of power line harmonics in RHIC are presented elsewhere in these proceedings.

• G. D'Auria
  
• D. Bacescu, L. Badano, C. Bontoiu, F. Cianciosi, P. Craievich, M. B. Danailov, S. Di Mitri, M. Ferianis, G. C. Pappas, G. Penco, A. Rohlev, A. Rubino, L. Rumiz, S. Spampinati, M. Trovo, A. Turchet, D. Wang
  ELETTRA, Basovizza, Trieste

• M. Svandrlik
  
• S. Bassanese, A. Carniel, K. Casarin, D. Castronovo, P. Craievich, G. D'Auria, R. De Monte, P. Delgiusto, S. Di Mitri, A. Fabris, R. Fabris, M. Ferianis, F. Giacuzzo, F. Iazzourene, G. L. Loda, M. Lonza, F. M. Mazzolini, D. M. Molaro, G. Pangon, C. Pasotti, G. Penco, L. Pivetta, L. Rumiz, C. Scafuri, G. Tromba, A. Vascotto, R. Visintini, D. Zangrando
  ELETTRA, Basovizza, Trieste
• L. Picardi, C. Ronsivalle
  ENEA C. R. Frascati, Frascati (Roma)

• S. Takama
  
• R. T. Dowd, A. Jackson, G. LeBlanc, K. Zingre
  ASP, Clayton, Victoria
• Y. Hirata, H. Kamikubo, Y. Nobusada, H. Suzuki
  Toshiba, Yokohama

• J. Kulesza
  
• N. Chen
  SSRF, Shanghai
• A. Deyhim
  Advanced Design Consulting, Inc, Lansing, New York

This paper summarizes the primary controller that is based on Schneider Premium PLC for two in-vacuum undulators to be installed at SSRF. The PLC controls a single gap stepper motor and driver, both made by Parker-Hannifin. Position feedback is derived from a TR Electronics linear absolute LTS-240 encoder mounted across the gap. The encoder resolution is programmable down to .1 um per count. Since the encoder is absolute there will be no need to home the gap axis. The advantage of linear encoders is the measurement is more direct and is not subject to wind-up and deflection that a rotary encoder would see on the end of a ball screw. Two encoders are planned, one on each end of the magnet array. One encoder will be the primary feedback for the axis and the other will detect deflection errors and girder taper. Four limits are provided as well as 4 kill switches. The 4 switches (2 limits and 2 kills) at min gap are optical and the 4 outer switches (2 limits and 2 kills) are mechanical. The limits prevent further motion in the direction they protect but allow the axis to be driven in the other direction (off the switch).

• C. Spackman
  
• A. Deyhim
  Physics Teachers Association, Knoxville, Tennessee
• E. A. Johnson
  Advanced Design Consulting, Inc, Lansing, New York
• J. T. Thånell, E. J. Wallen
  MAX-lab, Lund

Advanced Design Consulting developed control software entitled IDcontrol for its state-of-the-art Apple II insertion devices (ID). These IDs feature 8 controllable axes: four servo motors control the gap and taper of two main girders, and four servo motors control the photon polarization-state by manipulating four sub-girders. IDcontrol simultaneously positions all 8 axes with high precision in real-time using 0.1 micron linear encoders attached directly to the girders and sub-girders. Helical and Inclined Plane phase modes are supported with automated mode switching. Magnetic-field-correction-coil current and girder taper are adjustable as functions of gap, phase, and phase mode. IDcontrol continuously monitors redundant encoder velocity and position data for maximal reliability, encoder failure detection, and damage prevention. Combined with ADCs Graphical User Interface (GUI) entitled IDgui, IDcontrol manipulates the ID, provides user notification and automated recovery from errors, management of correction data, and isometric visualization of the ID's girders. The functionality of both IDcontrol and IDgui has been demonstrated at MAX lab and the results will be discussed.

• W. E. White
  
• J. Castro, P. Emma, A. Gilevich, C. Limborg-Deprey, H. Loos, A. Miahnahri
  SLAC, Menlo Park, California

• W. Guo
  
• G. L. Carr, S. Krinsky, J. Rose
  BNL, Upton, Long Island, New York

A notable feature of the proposed National Synchrotron Light Source II is that the vertical emittance is close to the diffraction limit of 1 Angstrom. With such a small emittance, the brightness is strongly affected by the longitudinal parameters, such as the momentum spread. Various effects are discussed and tolerances on the longitudinal parameters will be given. The lower level RF feedback system will be designed based on these tolerances.

• V. Litvinenko
  
• J. Alduino, D. Beavis, I. Ben-Zvi, M. Blaskiewicz, J. M. Brennan, A. Burrill, R. Calaga, P. Cameron, X. Chang, K. A. Drees, G. Ganetis, D. M. Gassner, J. G. Grimes, H. Hahn, L. R. Hammons, A. Hershcovitch, H.-C. Hseuh, A. K. Jain, D. Kayran, J. Kewisch, R. F. Lambiase, D. L. Lederle, C. Longo, G. J. Mahler, G. T. McIntyre, W. Meng, T. C. Nehring, B. Oerter, C. Pai, D. Pate, D. Phillips, E. Pozdeyev, T. Rao, J. Reich, T. Roser, T. Russo, Z. Segalov, J. Smedley, K. Smith, J. E. Tuozzolo, G. Wang, D. Weiss, N. Williams, Q. Wu, K. Yip, A. Zaltsman
  BNL, Upton, Long Island, New York
• H. Bluem, M. D. Cole, A. J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A. M.M. Todd
  AES, Princeton, New Jersey
• B. W. Buckley
  CLASSE, Ithaca
• G. Citver
  Stony Brook University, StonyBrook
• J. R. Delayen, L. W. Funk, H. L. Phillips, J. P. Preble
  Jefferson Lab, Newport News, Virginia

In this paper we present status and plans for the 20-MeV R&D energy recovery linac, which is under construction at Collider Accelerator Department at BNL. The facility is based on high current (up to 0.5 A of average current) super-conducting 2.5 MeV RF gun, single-mode super-conducting 5-cell RF linac and about 20-m long return loop with very flexible lattice. The R&D ERL, which is planned for commissioning in 2008, aims to address many outstanding questions relevant for high current, high brightness energy-recovery linacs.

• P. A. Elkiaer
  
• S. L. Birch, E. P. Quinn, S. P. Stoneham
  STFC/RAL/ISIS, Chilton, Didcot, Oxon
• C. E. Hansen, N. Hauge, C. Nielsen, E. Steinmann
  Danfysik A/S, Jyllinge
• A. Morris
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

• M. Ikegami
  
• H. Asano, T. Kobayashi
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• K. Hasegawa, T. Ito, T. Morishita, S. Sato, A. Ueno
  JAEA/LINAC, Ibaraki-ken
• Z. Igarashi, H. Tanaka
  KEK, Ibaraki
• H. Sako
  JAEA, Ibaraki-ken

• M. Yoshii
  
• S. Anami, E. Ezura, K. Hara, Y. Hashimoto, C. Ohmori, A. Takagi, M. Toda
  KEK, Ibaraki
• K. Haga, K. Hasegawa, M. Nomura, A. Schnase, F. Tamura, M. Yamamoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

masahito.yoshii@kek.jp

• J.-H. Jang
  
• Y.-S. Cho, K. Y. Kim, H.-J. Kwon
  KAERI, Daejon

The 100 MeV Linac of the Proton Engineering Frontier Project (PEFP) consists of an ion source, a low energy beam transport (LEBT), a 3 MeV radio frequency quadrupole (RFQ), and an 100 MeV drift tube linac (DTL). The DTL is separated into two parts. The first part includes 4 tanks which accelerate 20 mA proton beams up to 20 MeV. The medium energy beam transport (MEBT) follows the 20 MeV accelerator in order to match proton beams into the next linac as well as to extract and supply 20 MeV proton beams to the user facilities. The second part of the DTL consists of 7 tanks to accelerate proton beams to 100 MeV. This work focuses on the error analysis of the designed 100 MeV linac in order to obtain the tolerance limit in the fabrication and alignment processes of the linac as well as to study the steering magnets which control the beam fluctuations and reduce the potential beam loss.

• F. Caspers
  
• P. Borowiec, T. Kroyer, Z. Sulek, L. R. Williams
  CERN, Geneva

• K. Foraz
  
• E. Barbero-Soto, H. Gaillard, C. Hauviller, S. Weisz
  CERN, Geneva

• B. Goddard
  
• B. Balhan, E. H.R. Gaxiola, M. Gourber-Pace, L. K. Jensen, V. Kain, A. Koschik, T. Kramer, J. A. Uythoven, H. Vincke, J. Wenninger
  CERN, Geneva

• Th. Weiler
  
• G. Arduini, R. W. Assmann, C. B. Bracco, H.-H. Braun, B. Dehning, P. Gander, E. B. Holzer, M. Jonker, R. Losito, A. Masi, L. Ponce, S. Redaelli, G. Robert-Demolaize, M. Sobczak, J. Wenninger
  CERN, Geneva

• B. C. Brown
  
• D. Capista, I. Kourbanis, N. V. Mokhov, V. Sidorov
  Fermilab, Batavia, Illinois

A collimation system has been created for removing proton beam halo in the 8 GeV transfer line from the Fermilab Booster to Main Injector. A pair of 1.14 meter collimators with 5.08 cm rectangular apertures are installed in a 5 meter straight section. Horizontal and vertical motion systems allow them to be positioned such that halo can be scraped from four sides. An additional pair of collimators, placed one cell (90 degrees) downstream scrape halo which is of opposite phase. Each collimator pair can scrape about 600 Watts of beam power, limited by long term activation of materials outside of the beam line tunnel. Personnel exposure is reduced by surrounding the iron absorber with a layer of marble. Design features,radiation calculations and instrumentation considerations will be described.

• P. M. McIntyre
  
• R. Romero, A. Sattarov
  Texas A&M University, College Station, Texas

A conceptual design is presented for the 50 Tesla superconducting solenoids that are required for an optimized fast cooling ring in current designs for multi-TeV muon colliders. The solenoid utilizes high-performance multi-filament Bi-2212/Ag round strand. The conductor is a cable-in-conduit consisting of six such strands cabled around a thin-wall spring tube then drawn within an outer sheath. The spring tube and the sheath are made from high-strength superalloy Inconel. The solenoid coil comprises 5 concentric shells supported independently in the conventional manner. Each shell consists of a winding of the structured cable, impregnated in the voids between cables but empty inside so that the spring tubes decouple stress so that it cannot strain-degrade the fragile strands, and a high-modulus overband. An expansion bladder is located between the winding and the overband, and is pressurized and then frozen to provide hydraulic compressive preload to each shell. This approach makes it possible to accommodate ~10 T field contribution from each shell without degradation, and provides distributed refrigeration so that heat is removed throughout the windings.

• J. A. Crittenden
  
• M. G. Billing
  CESR-LEPP, Ithaca, New York

Following two decades of operation at 5 GeV beam energy for studies of bottom quark bound states, the Cornell Electron Storage Ring (CESR) converted to 2 GeV operation in 2001 for the purpose of investigating bound states of charm quarks. This reduction of beam energy resulted in increased relative contributions of the beam-beam force. The beam-beam interaction has been found to have considerable consequences for the optics and for the injection aperture. We describe recent developments in our modelling of the beam-beam interaction, experimental validation techniques, and investigations into compensation strategies.

• S. D. Nelson
  
• G. J. Caporaso, B. R. Poole
  LLNL, Livermore, California

Proton accelerator structures for medical applications using Dielectric Wall Accelerator (DWA) technology allows for the utilization of high field gradients on the order of 100 MV/m to accelerate the proton bunch. Medical applications involving cancer therapy treatment usually desire short bunch lengths on the order of hundreds of picoseconds in order to limit the extent of the energy deposited in the tumor site (in 3D space, time, and deposited proton charge). Electromagnetic simulations of the DWA structure, in combination with injections of proton bunches, have been performed using 3D finite difference codes in combination with particle pushing codes. Electromagnetic simulations of DWA structures includes these effects and also includes the details of the switch configuration and how that switch time affects the electric field pulse which accelerates the particle beam. Design trade-offs include the driving switch effects, layer-to-layer coupling analysis and its affect on the pulse rise time.

• K. W. Jones
  
• J. L. Erickson, F. R. Gallegos
  LANL, Los Alamos, New Mexico

At the core of the Los Alamos Neutron Science Center (LANSCE) accelerator lies an 800-MeV proton linac that drives user facilities for isotope production, proton radiography, ultra-cold neutrons, weapons neutron research and for various sciences using neutron scattering. LANSCE is in the planning phase of a refurbishment project that will sustain reliable facility operations well into the next decade. The general goals for LANSCE-R are to (1) preserve dependable operation of the linac and (2) increase the cost effectiveness of operations. Requirements can be met for overall beam intensity, availability, and reliability with long-term sustainability and minimal disruption to scheduled user programs. The baseline refurbishment project consists of replacing the 201 MHz RF systems, upgrading a substantial fraction of the 805 MHz RF systems, updating the control system, and replacing or improving a variety of diagnostics and accelerator subsystems. The plans for the various LANSCE-R improvements will be presented and the preliminary cost and schedule estimates will be discussed.

• K. Fong
  
• M. P. Laverty, Q. Zheng
  TRIUMF, Vancouver

• P. Marchand
  
• P. Bosland, P. Bredy
  CEA, Gif-sur-Yvette
• H. D. Dias, M. D. Diop, M. E. El Ajjouri, J. L. Labelle, R. L. Lopes, M. Louvet, C. M. Monnot, F. Ribeiro, T. Ruan, R. Sreedharan, K. Tavakoli, C. G. Thomas-Madec
  SOLEIL, Gif-sur-Yvette

• K. Dunkel
  
• B. A. Aminov
  CRE, Wuppertal
• J. Hottenbacher, C. Piel
  ACCEL, Bergisch Gladbach

• M. K. Grecki
  
• W. Koprek, S. Simrock
  DESY, Hamburg

Measurements of effective Radio Frequency (RF) field parameters (amplitude and phase) are tasks of great importance in high-energy accelerators*. The RF signal is downconverted in frequency to intermediate frequency (IF) but keeping the information about amplitude and phase. The IF signal is then sampled in ADC and processed in digital IQ detector computing the I and Q components**. The downconverter is a nonlinear device thus not only the fundamental frequency but also its harmonics are present and sampled by ADC. For a typical downconverter (used in FLASH LLRF system) the higher order harmonics levels depend on RF signal level and are about 40dBm lower than the fundamental frequency component. These harmonics can produce errors in IQ detector of up to few percent in amplitude and few degree in phase. These errors depends not only on nonlinearity of downconverter but also on the IQ detection scheme*** (IF and sampling rate SR). The paper presents the optimization of the IQ detection scheme (choosing the IF and SR) taking into account the nonlinear characteristics of the downconverter.

*Grelick A. et all:A High-Resolution…, Proc. LINAC 2004,715-718**Grecki M. et all:Estimation of IQ…, Proc. MIXDES 2005,783-788***Simrock S. et all:Considerations…, Proc. EPAC 2006,1462-1464

• M. Hoffmann
  
• F. Ludwig, H. Schlarb, S. Simrock
  DESY, Hamburg

For pump- and probe experiments at VUV- and X-ray free-electron lasers the stability of the electron beam and timing reference must be guaranteed in phase for the injector and bunch compression section within a resolution of 0.01 degree (rms) and in amplitude within 1 10^-4 (rms). The performance of the field detection and regulation of the acceleration RF critically influences the phase and amplitude stability. For the RF field control, a multichannel RF downconverter is used to detect the field vectors and control the vectorsum of 32 cavities. In this paper a new design of an 8 channel downconverter is presented. The downconverter frontend consists of a passive rf double balanced mixer input stage, intermediate filters and an integrated 16bit analog-to-digital converter (ADC). The design includes a digital motherboard for data preprocessing and communication with the controller. In addition we characterize the downconverter performance in amplitude and phase jitter, temperature drifts and channel crosstalk in laboratory environment as well as for accelerator operation.

• E. Vogel
  
• C. Gerth, W. Koprek, F. Loehl, D. Noelle, H. Schlarb, T. Traber
  DESY, Hamburg

At pulsed linear accelerators, fast proportional rf control compensates beam loading sufficiently for single or a few bunches. In the case of long bunch trains, additional measures have to be taken commonly by adding a compensation signal to the rf drive signals calculated from the predicted beam intensity. In contrast to predictive methods, techniques based on real time beam measurements are sensitive to fast changes of the beam intensity and bunch patterns. At FLASH we apply a beam loading compensation scheme based on toroid monitor signals. This paper presents the compensation scheme, the calibration procedure and the effect on the beam.

• Z. Fang
  
• S. Anami, S. Michizono, S. Yamaguchi
  KEK, Ibaraki
• T. Kobayashi
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• H. Suzuki
  JAEA, Ibaraki-ken

• T. Higo
  
• F. Furuta, Y. Higashi, T. Saeki, K. Saito, M. Satoh, H. Yamaoka
  KEK, Ibaraki

• E. Kako
  
• H. Hayano, S. Noguchi, T. Shishido, K. Watanabe, Y. Yamamoto
  KEK, Ibaraki

• T. Matsumoto
  
• S. Fukuda, H. Katagiri, S. Michizono, Y. Yano
  KEK, Ibaraki
• Z. Geng
  IHEP Beijing, Beijing

• S. Michizono
  
• S. Fukuda, H. Katagiri, T. Matsumoto, T. Miura, Y. Yano
  KEK, Ibaraki
• Z. Geng
  IHEP Beijing, Beijing

• F. Tamura
  
• S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
  KEK, Ibaraki
• K. Hasegawa, M. Nomura, A. Schnase, M. Yamamoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

• T. Kobayashi
  
• S. Anami, Z. Fang, Y. Fukui, M. Kawamura, S. Michizono, K. Nanmo, S. Yamaguchi
  KEK, Ibaraki
• E. Chishiro, T. Hori, H. Suzuki, M. Yamazaki
  JAEA, Ibaraki-ken

• A. Schnase
  
• S. Anami, E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
  KEK, Ibaraki
• M. Nomura, F. Tamura, M. Yamamoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

* C. Ohmori at. al, "High Field-Gradient Cavity for J-PARC 3 GeV RCS", PAC 2004

• Y. Iwashita
  
• H. Fujisawa, M. Ichikawa, Y. Tajima
  Kyoto ICR, Uji, Kyoto

• L. Shen
  
• Y. L. Chi, Q. M. Dai, X. W. Yang
  IHEP Beijing, Beijing

• L. Shen
  
• Y. L. Chi, C. Huang
  IHEP Beijing, Beijing

• P. M. Sekalski
  
• J. W. Jalmuzna, A. Napieralski
  TUL-DMCS, Lodz
• L. Lilje, K. P. Przygoda, S. Simrock
  DESY, Hamburg
• R. P. Paparella
  INFN/LASA, Segrate (MI)

The SC cavities need a fast tuning system, which is able to adjust the shape during the pulse operation. The first attempts were focused on the compensation of the repetitive and periodic distortion. The algorithms were implemented in Matlab and allow compensating only the Lorentz force detuning. However, the previous solution was too slow to be able to compensate the microphonics. The paper presents recent development in the field. The previously worked out algorithms are implemented in the FPGA-based control system. The SIMCON board is used, which allows to perform parallel, deeply pipelined calculation. The new approach allows integrating the algorithm dedicated for cavity shape control with the LLRF system used for vector sum control. Moreover, the new algorithm for on-line detuning calculation which base on the electromechanical model of the cavity is presented. The system is tested with Module Test Stand (MTS) at DESY with the high gradient cavities (37 MV/m). The active elements are the NOLIAC's and PI's multilayer, low voltage piezostacks. The paper will present the first results from these measurements.

• S. An
  
• Y.-S. Cho, B. H. Choi, C. Gao
  KAERI, Daejon

A new type of coaxial higher-order mode (HOM) coupler with one hook and two stubs has been designed for PEFP SRF cavities to satisfy the HOM damping requirements of the superconducting RF (SRF) linac of the Proton Engineering Frontier Project (PEFP), and to overcome the notch frequency shift and feed-through tip melting issues. This paper has presents details on the PEFP HOM coupler?s structure, structure optimization, filter characteristics, electro-magnetic field distribution and a coupler installation tool.

• H. S. Kim
  
• Y.-S. Cho, I.-S. Hong, D. I. Kim, H.-J. Kwon, K. T. Seol, Y.-G. Song
  KAERI, Daejon

The RF amplitude and the phase stability requirements of the LLRF system for the PEFP(Proton Engineering Frontier Project) proton linac are within 1% and 1 degree, respectively. As a prototype of the LLRF, a simple digital PI control system based on commercial FPGA board is designed and tested. The main features are a sampling rate of 40 MHz which is four times higher than the down-converted cavity signal frequency, digital in-phase and quadrature detection, pulsed mode operation with the external trigger, and a simple proportional-integral feedback algorithm implemented in a FPGA. The developed system was tested with 3 MeV RFQ and 20 MeV DTL, and satisfied the stability requirements.

• K. T. Seol
  
• Y.-S. Cho, D. I. Kim, H. S. Kim, H.-J. Kwon
  KAERI, Daejon

The PEFP LLRF system for the 3MeV RFQ and 20MeV DTL has been developed. The stability of ±1% in the amplitude and ±1˚ in the phase is required. Therefore, the drift of the analog components should be low to satisfy the requirement. Analog chassis as a prototype of LLRF system is configured and tested. RF components including an IQ modulator, an RF switch, a mixer, phase comparators, RF splitters, RF filters and trip circuit for high VSWR are installed in this chassis. This performs the shift of RF amplitude and phase from IQ signal, down-conversion to 10MHz IF signal, interlock for arc and high VSWR, and RF/clock distribution. The amplitude and phase stability of each component are measured to check the effect on the whole system performance. The detailed configuration and test results are presented.

• K. R. Kim
  
• Y.-S. Cho, H.-J. Kwon
  KAERI, Daejon
• W. H. Hwang, H. S. Kim, H.-G. Kim, S. J. Kwon, J. Park, J. C. Yoon
  PAL, Pohang, Kyungbuk

The temperature-controlled cooling water system was designed to obtain the resonance frequency stabilization of the normal conducting drift tube linac (DTL) for the PEFP 100 MeV proton accelerator. The primary sizing of individual closed-loop low conductivity cooling water pumping skids for each DTL system was conducted with a simulation of thermo-hydraulic network model. The temperature control schemes incorporating the process dynamic model of heat exchangers were examined to regulate the input water temperatures into the DTL during the steady state operation. The closed water circuits to achieve system performance and stability for low and full duty operation modes were discussed, and numerical results were also presented.

• S. Doebert
  
• C. Adolphsen, L. Laurent
  SLAC, Menlo Park, California
• R. Fandos, A. Grudiev, S. T. Heikkinen, J. A. Rodriguez, M. Taborelli, W. Wuensch
  CERN, Geneva

• J. Alex
  
• M. Bader, J. Troxler
  Thomson Broadcast & Multimedia AG, Turgi

Thomson Broadcast & Multimedia has been awarded a contract from DESY to design and build a prototype klystron modulator for the XFEL project. This modulator will be built in pulse step modulator (PSM) technology. This technology will allow to control the pulse form to achieve a maximum flatness of the pulse without tuning any high power components. The modulator will also have a built-in power regulation to prevent voltage flicker of the mains. The paper will give an overview about the principles of the modulator and presents the status of the design. It also shows simulation results about the expected performance.

• C. W. Appelbee
  
• A. Daly
  STFC/RAL, Chilton, Didcot, Oxon
• A. Seville
  STFC/RAL/ISIS, Chilton, Didcot, Oxon

• G. Burt
  
• C. D. Beard, P. Goudket, P. A. McIntosh
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• L. Bellantoni
  Fermilab, Batavia, Illinois
• R. G. Carter, A. C. Dexter, R. O. Jenkins
  Cockcroft Institute, Lancaster University, Lancaster

The ILC crab cavity will require the design of an appropriate power coupler. The beamloading in dipole cavities is considerably more variable than accelerating cavities, hence simulations have been performed to establish the required external Q. Simulations of a suitable coupler were then performed and were verified using a normal conducting prototype with variable coupler tips.

• A. C. Dexter
  
• C. D. Beard, P. Goudket, A. Kalinin, L. Ma, P. A. McIntosh
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• G. Burt, R. G. Carter, R. O. Jenkins, M. I. Tahir
  Cockcroft Institute, Lancaster University, Lancaster

The ILC reference design report (RDR) recommends a 14 mrad crossing angle for the positron and electron beams at the IP. A matched pair of crab cavity systems are required in the beam delivery system to align both bunches at the IP. The use of a multi-cell, 3.9GHz dipole mode superconducting cavity, derived from the Fermilab CKM cavity. Dipole-mode cavities phased for crab rotation are shifted by 90 degrees with respect to similar cavities phased for deflection. Uncorrelated phase errors of 0.086 degrees (equivalent to 61fs) for the two cavity systems, gives an average of 180nm for the relative deflection of the bunch centers. For a horizontal bunch size of 655nm, a deflection of 180nm reduces the ILC luminosity by 2%. The crab cavity systems are to be placed ~28m apart and their synchronization to within 61fs is on the limit of what is presently achievable. This paper describes the design and testing of circuits and control algorithms under development at the Cockcroft Institute in the UK for proof of principle experiments planned on the ERLP at Daresbury and on the ILCTA test beamline at FNAL. Simulation results for measurement and control systems are also given.

• D. Cook
  
• J. Clare, P. W. Wheeler
  University of Nottingham, Nottingham
• J. S. Przybyla
  e2v, Essex

• A. E. Grelick
  
• A. R. Cours, N. P. Di Monte, A. Nassiri, T. Smith, G. J. Waldschmidt
  ANL, Argonne, Illinois

The Phase I Advanced Photon Source Deflecting Cavity System for producing short X-ray pulses uses one multi-cell, S-band cavity to apply a deflecting voltage to the stored electron beam ahead of an undulator that supports a beamline utilizing short picosecond X-rays. Two additional multi-cell cavities are then used to cancel out the perturbation and redirect the electron beam along the path of its nominal orbit. The pulsed rf system driving the deflecting cavities is described. Design tradeoffs are discussed with emphasis on topology considerations and digital control loops making use of sampling technology in a manner consistent with the present state of the art.

• M. E. Middendorf
  
• F. R. Brumwell, J. C. Dooling, D. Horan, R. Kustom, M. K. Lien, G. E. McMichael, M. R. Moser, A. Nassiri, S. Wang
  ANL, Argonne, Illinois

The Intense Pulsed Neutron Source (IPNS) rapid cycling synchrotron (RCS) is used to accelerate protons from 50 MeV to 450 MeV, at a repetition rate of 30 Hz. The original ring design included two identical RF systems, each consisting of an accelerating cavity, cavity bias supply, power amplifiers and low level analog electronics. The original cavities are located 180 degrees apart in the ring, and provide a total peak accelerating voltage of ~21 kV over the 2.21 MHz to 5.14 MHz revolution frequency sweep. A third RF system has been constructed and installed in the RCS. The third RF system is capable of operating at the fundamental revolution frequency for the entire acceleration cycle, providing an additional peak accelerating voltage of up to ~11kV, or at the second harmonic of the revolution frequency for the first ~4 ms of the acceleration cycle, providing an additional peak voltage of up to ~11kV for bunch shape control, resulting in a modest increase in bunch length. We describe here to date, the hardware implementation and operation of the third RF cavity in the second harmonic mode.

• J. Branlard
  
• G. I. Cancelo, R. H. Carcagno, B. Chase, H. Edwards, R. P. Fliller, B. M. Hanna, E. R. Harms, A. Hocker, T. W. Koeth, M. J. Kucera, A. Makulski, U. Mavric, M. McGee, A. H. Paytyan, Y. M. Pischalnikov, P. S. Prieto, R. Rechenmacher, J. Reid, K. R. Treptow, N. G. Wilcer, T. J. Zmuda
  Fermilab, Batavia, Illinois

As part of the research and development towards the International Linear Collider (ILC), several test facilities have been developed at Fermilab. This paper presents the latest LLRF results obtained with Capture Cavity II at these test facilities. The main focus will be on controls and RF operations using the SIMCON based LLRF system. Details about hardware upgrades and overall system performance will be also explained. Finally, design considerations and objectives for the future test facility at the New Muon Laboratory (NML) will be presented.

• T. W. Koeth, T. W. Koeth
  Rutgers University, The State University of New Jersey, Piscataway, New Jersey
• J. Branlard, H. Edwards, R. P. Fliller, E. R. Harms, A. Hocker, M. McGee, Y. M. Pischalnikov, P. S. Prieto, J. Reid
  Fermilab, Batavia, Illinois

Valuable experience in operating and maintaining superconducting RF cavities in a horizontal test module has been gained with Capture Cavity II. We report on all facets of our experience to date.

• E. R. Harms
  
• T. T. Arkan, L. Bellantoni, H. Carter, H. Edwards, M. Foley, T. N. Khabiboulline, D. V. Mitchell, D. R. Olis, A. M. Rowe, N. Solyak
  Fermilab, Batavia, Illinois

Fermilab is involved in an effort to assemble 3.9 GHz superconducting RF cavities into a four cavity cryomodule for use at the DESY TTF/FLASH facility as a third harmonic structure. The design gradient of these cavities is 14 MV/m limited by thermal heat transfer. This effort involves design, fabrication, intermediate testing, assembly, and eventual delivery of the cryomodule. We report on all facets of this enterprise from design through future plans. Included will be test results of single 9-cell cavities, lessons learned, and current status.

• U. Mavric
  
• J. Branlard, B. Chase, E. Cullerton, D. W. Klepec
  Fermilab, Batavia, Illinois

• J. P. Ozelis
  
• R. H. Carcagno, C. M. Ginsburg, Y. Huang, B. Norris, T. Peterson, V. Poloubotko, R. Rabehl, I. Rakhno, C. Reid, D. A. Sergatskov, C. Sylvester, M. Wong, C. Worel
  Fermilab, Batavia, Illinois

As part of a program to improve cavity performance reproducibility for the ILC, Fermilab is developing a facility for vertical testing of SRF cavities. It operates at a nominal temperature of 2K, using an existing cryoplant that can supply LHe in excess of 20g/sec and provides steady-state bath pumping capacity of 125W at 2K. The below-grade cryostat consists of a 4.9m long vacuum vessel and 4.5m long LHe vessel. The cryostat is equipped with external and internal magnetic shielding to reduce the ambient magnetic field to <10mG. Internal fixed and external movable radiation shielding ensures that radiation levels from heavily field-emitting cavities remain low. In the event that radiation levels exceed allowable limits, an integrated personnel safety system consisting of RF switches, interlocks, and area radiation monitors disables RF power to the cavity. In anticipation of increased throughput requirements that may be met with additional test stand installations, sub-systems have been designed to be easily upgradeable or to already meet these anticipated needs. Detailed facility designs, performance during system commissioning, and results from initial cavity tests are presented.

• J. P. Ozelis
  
• C. Grenoble, T. Powers
  Jefferson Lab, Newport News, Virginia
• R. Nehring
  Fermilab, Batavia, Illinois

Fermilab is developing a facility for vertical testing of SRF cavities as part of a program to improve cavity performance reproducibility for the ILC. The RF system for this facility, using the classic combination of oscillator, phase detector/mixer, and loop amplifier to detect the resonant cavity frequency and lock onto the cavity, is based on the proven production cavity test systems used at Jefferson Lab for CEBAF and SNS cavity testing. The design approach is modular in nature, using commercial-off-the-shelf (COTS) components. This yields a system that can be easily debugged and modified, and with ready availability of spares. Data acquisition and control is provided by a PXI-based hardware platform in conjunction with software developed in the LabView programming environment. This software provides for amplitude and phase adjustment of incident RF power, and measures all relevant cavity power levels, cavity thermal environment parameters, as well as field emission-produced radiation. It also calculates the various cavity performance parameters and their associated errors. Performance during system commissioning and initial cavity tests will be presented.

• Y. M. Pischalnikov
  
• J. Branlard, R. H. Carcagno, B. Chase, H. Edwards, A. Makulski, M. McGee, R. Nehring, D. F. Orris, V. Poloubotko, C. Sylvester, S. Tariq
  Fermilab, Batavia, Illinois

The technology for mechanically compensating Lorentz Force detuning in superconducting RF cavities has already been developed at DESY. One technique is based on commercial piezoelectric actuators and was successfully demonstrated on TESLA cavities*. Piezo actuators for fast tuners can operate in a frequency range up to several kHz; however, it is very important to maintain a constant preload force on the piezo stack in the range of 10 to 50% of its specified blocking force. Determining the preload force during cooldown, warm-up, or re-tuning of the cavity is difficult without instrumentation, and exceeding the specified range can permanently damage the piezo stack. A technique based on strain gauge technology for superconducting magnets has been applied to fast tuners for monitoring the preload on the piezoelectric assembly. This paper will address the design and testing of piezo actuator preload sensor technology. Results from measurements of preload sensors installed on the tuner of the DESY Capture Cavity II tested at Fermilab will be presented. These results include measurements during cooldown, warm-up, and cavity tuning along with dynamic Lorentz force compensation.

* M. Liepe et al," Dynamic Lorentz Force Compensation with a Fast Piezoelectric Tuner" PAC2001

• P. Varghese
  
• B. Barnes, J. Branlard, B. Chase, P. W. Joireman, D. W. Klepec, U. Mavric, V. Tupikov
  Fermilab, Batavia, Illinois

• M. A. Kempkes
  
• M. P.J. Gaudreau, I. Roth, R. P. Torti
  Diversified Technologies, Inc., Bedford, Massachusetts

• M. A. Kempkes
  
• M. P.J. Gaudreau, J. Kinross-Wright, I. Roth
  Diversified Technologies, Inc., Bedford, Massachusetts

• K. M. Baptiste
  
• P. W. Casey, S. Kwiatkowski, CA. Timossi
  LBNL, Berkeley, California

ALS, one of the first third generation synchrotron light sources which has been operating since 1992 at Berkeley Lab has been upgraded from its present operation scenario of injecting the 1.5GeV electron beam from the Booster ring into the Storage ring every 8 hours where it is accelerated to the final energy of 1.9GeV to full energy (1.9GeV) injection from the Booster ring into the Storage ring every 3 seconds for filling and every 30-35 seconds for Top-Off mode. Additionally the beam current has been increased from the time averaged value of 250mA to 500mA to increase the brightness. In this paper we will present the results of the new ALS injector RF system set-up for Top-Off mode of operation, the final design and operational results of the Booster RF power source and control system upgrades.

• L. R. Doolittle
  
• J. M. Byrd, A. Ratti, J. W. Staples, R. B. Wilcox
  LBNL, Berkeley, California
• G. D'Auria, M. Ferianis, M. M. Milloch, A. Rohlev
  ELETTRA, Basovizza, Trieste
• M. W. Stettler
  CERN, Geneva

• H. Padamsee
  
• B. Ashmanskas
  Fermilab, Batavia, Illinois
• M. D. Cole, A. J. Favale, J. Rathke
  AES, Princeton, New Jersey
• A. C. Crawford
  CLASSE, Ithaca

We have recently upgraded our chemical treatment, high pressure rinsing systems and low temperature RF testing system to prepare and test 9-cell cavities for ILC. After removal of 120 um by BCP we reached 26 MV/m accelerating field limited by the high-field Q-slope. There was no quench and no field emission, showing that our facilities are well qualified. We have also extended our vertical electropolishing system to 9-cell cavities. Previously we have successfully used vertical electropolishing for one-cell cavities of the re-entrant shape to reach 47 MV/m accelerating. Test results on 9-cell electropolished cavities will be presented. AES has manufactured the first 9-cell cavity with re-entrant cell shapes. The surface magnetic field is 10% lower than for the standard TESLA-shape cavity. Half-cells were electropolished 100 um before welding. We will present results on the first tests of the 9-cell re-entrant cavity.

• W. J. DeHope
  
• K. L. Griffin, R. Kihara, M. M. Ong, O. Ross
  LLNL, Livermore, California

The now-mature FXR (Flash X-Ray) radiographic facility at Lawrence Livermore National Laboratory will be briefly described with emphasis on its pulsed power system. The heart of each accelerating cell's pulse-forming Blumlein is it's sulfur hexafluoride-based triggered closing switch. FXR's recent upgrade to a recirculating SF6 gas reclamation system will be described and the resulting accelerator performance and reliability improvements documented. This was accompanied by a detailed switch breakdown study on FXR's Test Stand* and the recent analysis of the resulting statistics will be shown.

* W. DeHope, D. Goerz, R. Kihara, M. Ong, G. Vogtlin, J. Zentler, "An Induction Linac Test Stand", 21st Particle Accelerator Conference, Knoxville, TN, May 20, 2005

• S. Kwon
  
• J. Davis, M. T. Lynch, M. S. Prokop, S. Ruggles, P. A. Torrez
  LANL, Los Alamos, New Mexico

• J. T.M. Lyles
  
• S. Archuletta, D. Baca, J. Davis, D. Rees, P. A. Torrez
  LANL, Los Alamos, New Mexico

A new 200 MHz RF system is being developed for the LANSCE proton drift tube linac (DTL). A planned upgrade will replace parts of the DTL RF system with new generation components. When installed for the LANSCE-R project, the new system will reduce the total number of electron power tubes from twenty-four to seven in the DTL plant. The 3.4 MW final power amplifier will use a Thales TH628 Diacrode. This state-of-the-art device eliminates the large anode modulator of the present triode system, and will be driven by a new tetrode intermediate power amplifier. In this mode of operation, this intermediate stage will provide 150 kW of peak power. The first DTL tank requires up to 400 kW of RF power, which will be provided by the same tetrode driver amplifier. A prototype system is being constructed to test components, using some of the infrastructure from previous RF projects. High voltage DC power became available through innovative re-engineering of an installed system. A summary of the design and construction of the intermediate power amplifier will be presented and test results will be summarized.

• M. S. Prokop
  
• S. Kwon, S. Ruggles, P. A. Torrez
  LANL, Los Alamos, New Mexico

• W. Reass
  
• V. P. Derenchuk, T. Rinckel, G. Visser
  IUCF, Bloomington, Indiana
• D. Rees
  LANL, Los Alamos, New Mexico

This paper describes the Klystron RF systems for the Indiana University Low Energy Neutron Source (LENS) accelerator 425 MHz Radio Frequency Quadrupole (RFQ) and Drift Tube Linac (DTL) systems. Of interest in the power conditioning system is the design of the totem-pole grid-catch modulator for the mod-anode klystrons. This topology provides a fast rise and fall and closed loop regulation for the klystron mod-anode to cathode voltage, which minimizes RF amplitude and phase droop while maximizing efficiency. Another advantage is that short pulse high rep-rate operation is viable within the average power capabilities of the klystron. The 425 MHz, 1.25 MW klystron amplifier chain will also be detailed. Of final interest, is the digital low level RF system. This provides vector control of the cavity field using direct conversion, non-I/Q sampling architecture, at a sampling rate of 132 MHz with a 12-bit ADC. Four input and two output channels are integrated into a 6U VME module, with all DSP functions performed in Xilinx Spartan-3 field-programmable gate arrays. The design and implementation of these systems, coupled with LENS operational results, will be presented.

• D. Rees
  
• G. O. Bolme, J. T. Bradley III, S. Kwon, J. T.M. Lyles, M. T. Lynch, M. S. Prokop, W. Reass, K. A. Young
  LANL, Los Alamos, New Mexico

• R. Akre
  
• J. M. Byrd
  LBNL, Berkeley, California
• D. Dowell, P. Emma, J. C. Frisch, B. Hong, K. D. Kotturi, P. Krejcik, J. Wu
  SLAC, Menlo Park, California

The Linac Coherent Light Source at SLAC will be the brightest X-ray laser in the world when it comes on line. In order to achieve the brightness a 100fS length electron bunch is passed through an undulator. To creat the 100fS bunch, a 10pS electron bunch, created from a photo cathode in an RF gun, is run off crest on the RF to set up a position to energy correlation. The bunch is then compressed chicanes. The stability of the RF system is critical in setting up the position to energy correlation. Specifications derived from simulations require the RF system to be stable to below 100fS in several critical injector stations and the last kilometer of linac. The SLAC linac RF system is being upgraded to meet these requirements.

• K. L.F. Bane
  
• C. Adolphsen, C. D. Nantista
  SLAC, Menlo Park, California

The nominal design gradient for the ILC is 31.5 MV/m, but the L-band superconducting cavities built to date have demonstrated a range in sustainable gradient extending below this goal, limited by Q-dropoff and quenching. An economically feasible cavity acceptance rate will include in the linacs a certain percentage of sub-performing cavities. We examine how, with a customizable RF distribution scheme, one can most efficiently distribute power from one klystron amongst 24 nine-cell cavities. The nominal cavity fills to the design gradient at the time the beam arrives, after which the beamloading voltage exactly cancels any further rise, yielding constant gradient during the bunch train. Along with adjustable RF power, we assume adjustable cavity coupling, or loaded quality factor, so that the gradient can be leveled in non-nominal cavities, to avoid quench-inducing overshoots. We explore these and related issues for the ILC linac high-power RF.

• M. N. Nguyen
  
• R. L. Cassel
  SLAC, Menlo Park, California

A compact, water cooled, high power switch for the Superconducting Module Test Facility (SMTF) long-pulse klystron modulator has been designed and implemented at the Fermi National Accelerator Laboratory (FNAL). This solid-state switch is composed of six series devices, each having a rating of 4.5 kV at 2000 Adc. Latest generation, press-pack IGBT modules are utilized to reduce the physical size and complexity of the switch assembly. The new switch and its associated controller provide a high degree of redundancy and fail-safe operation, which meets the modulator requirements. This paper describes the general switch assembly, IGBT protection and control schemes, and test results.

• G. C. Pappas
  
• G. D'Auria, P. Delgiusto, L. Veljak
  ELETTRA, Basovizza, Trieste

1. "NLC Hybrdi Solid State Induction Modulator" R. L. Cassel, etal, Lubeck, Germany, Linac 2004.

• J. D. Fox
  
• T. Mastorides, C. H. Rivetta, D. Van Winkle
  SLAC, Menlo Park, California

Several high-current accelerators use feedback techniques in the accelerating RF systems to control the impedances seen by the circulating beam. These Direct and Comb Loop architectures put the high power klystron and LLRF signal processing components inside feedback loops, and the ultimate behavior of the systems depends on the individual sub-component properties. Imperfections and non-idealities in the signal processing leads to reduced effectiveness in the impedance controlled loops. In the PEP-II LLRF systems non-linear effects have been shown to reduce the achievable beam currents, increase low-mode longitudinal growth rates and reduce the margins and stability of the LLRF control loops. We present measurements of the driver amplifiers used in the PEP-II systems, and present measurement techniques needed to quantify the small-signal gain, linearity, transient response and image frequency generation of these amplifiers. Results are presented from measurements of 5 different types of amplifiers, and the trade-offs in selecting between them highlighted.

• Q. S. Shu
  
• I. Ben-Zvi
  BNL, Upton, Long Island, New York
• G. Cheng, I. M. Phipps, J. T. Susta
  AMAC, Newport News, Virginia
• P. Kneisel, G. Myneni
  Jefferson Lab, Newport News, Virginia
• J. Mast, R. Selim
  CNU, Newport News

Currently available technology can only inspect flat sheets and allow the elimination of defective flat sheets before the expensive forming and machining of the SRF cavity half-cells, but it does not eliminate the problem of remaining or uncovered surface impurities after partial chemical etching of the half-cells, nor does it detect any defects that may have been added during the fabrication of the half-cells. AMAC has developed a SQUID scanning system based on eddy current technique that allows the scanning of curved Nb samples that are welded to make superconducting RF cavity half-cells. AMAC SQUID scanning system successfully located the defects (Ta macro particles about 100 mm diameter) in a flat Nb sample (top side) and was able to also locate the defects in a cylindrical surface sample (top side). It is more significant that the system successfully located the defects on the backside of the flat sample and curved sample or 3-mm from the top surface. The 3-D SQUID-based Nondestructive instrument will be further optimized and improved in making SRF cavities and allow inspection and detection during cavity manufacturing for achieving highest accelarating fields.

• C. Hovater
  
• T. L. Allison, J. R. Delayen, J. Musson, T. E. Plawski
  Jefferson Lab, Newport News, Virginia

We have developed a digital process that emulates an analog oscillator and ultimately a self excited loop (SEL) for field control. The SEL, in its analog form, has been used for many years for accelerating cavity field control. In essence the SEL uses the cavity as a resonant circuit – much like a resonant ?tank? circuit is used to build an oscillator. An oscillating resonant circuit can be forced to oscillate at different, but close, frequencies to resonance by applying a phase shift in the feedback path. This allows the circuit to be phased locked to a master reference, which is crucial for multiple cavity accelerators. For phase and amplitude control the SEL must be forced to the master reference frequency, and feedback provided for in both dimensions. The novelty of this design is in the way digital signal processing (DSP) is structured to emulate an analog system. While the digital signal processing elements are not new, to our knowledge this is the first time that the digital SEL concept has been designed and demonstrated. This paper reports on the progress of the design and implementation of the digital SEL for field control of superconducting accelerating cavities.

• T. E. Plawski
  
• T. L. Allison, G. K. Davis, H. Dong, C. Hovater, K. King, J. Musson
  Jefferson Lab, Newport News, Virginia

The new digital LLRF system for the CEBAF 12GeV accelerator will perform a variety of tasks, beyond field control.* In this paper we present the superconducting cavity resonance control system designed to minimize RF power during gradient ramp and to minimize RF power during steady state operation. Based on the calculated detuning angle, which represents the difference between reference and cavity resonance frequency, the cavity length will be adjusted with a mechanical tuner. The tuner has two mechanical driving devices, a stepper motor and a piezo-tuner, to yield a combination of coarse and fine control. Although LLRF piezo processing speed can achieve 10 kHz bandwidth, only 10 Hz speed is needed for 12 GeV upgrade. There will be a number of additional functions within the LLRF system; heater controls to maintain cryomodule's heat load balance, ceramic window temperature monitoring, waveguide vacuum interlocks, ARC detector interlock and quench detection. The additional functions will be divided between the digital board, incorporating an Altera FPGA and an embedded EPICS IOC. This paper will also address hardware evolution and test results performed with different SC cavities.

*RF Control Requirements for the CEBAF Energy Upgrade Cavities, C. Hovater, J. Delayen, L. Merminga, T. Powers, C. Reece, Proceedings 2000 Linear Accelerator Conference, Monterey, CA , August 2000

• Y. W. Kang
  
• M. S. Champion, T. W. Hardek, S.-H. Kim, M. P. McCarthy, A. V. Vassioutchenko, J. L. Wilson
  ORNL, Oak Ridge, Tennessee

High power vector modulators can allow a fan-out RF power distribution system that can power many accelerating cavities from a single high-power klystron amplifier. The configuration enables independent control of amplitudes and phases of RF voltages at the cavities. A vector modulator employs either one or two hybrids with two fast phase shifters. Prototype high power RF vector modulators employing a hybrid and two fast ferrite phase shifters in coaxial TEM transmission lines for 402.5 MHz and 805 MHz are built and tested. RF properties of the design and result of high power testing are presented.

• J. J. Mize, J. J. Mize
  ORNL, Oak Ridge, Tennessee

The high frequency switching megawatt-class High Voltage Converter Modulator (HVCM) developed by Los Alamos National Laboratory for the Oak Ridge National Laboratory's Spallation Neutron Source (SNS), is now in operation. One of the major problems with the modulator systems is shoot-thru conditions that can occur in an IGBTs H-bridge topology resulting in large fault currents and device failure in a few microseconds. The Dynamic Fault Detection Chassis (DFDC) is a fault monitoring system; it monitors transformer flux saturation using a window comparator and dV/dt events on the cathode voltage caused by any abnormality such as capacitor breakdown, transformer primary turns shorts, or dielectric breakdown between the transformer primary and secondary. If faults are detected, the DFDC will inhibit the IGBT gate drives and shut the system down, significantly reducing the possibility of a shoot-thru condition or other equipment damaging events. In this paper,we will present system integration considerations, performance characteristics of the DFDC, and discuss its ability to significantly reduce costly down time for the entire facility.

• Y. Zhang
  
• I. E. Campisi, C. Deibele, J. Galambos, S. Henderson, Y. W. Kang, H. Ma, J. L. Wilson
  ORNL, Oak Ridge, Tennessee

Beam phase measurement based on detection of transient beam loading signal in a Superconducting (SC) cavity is utilized to setup the cavity synchronous phase. It has the potential to become a fast tune-up technique for a high intensity SC electron linac, as cavity phase could be determined precisely with only a few beam pulses. The paper introduces a transient detector study in the Spallation Neutron Source (SNS) proton linac, and discusses one of the major challenges - stochastic noise in the cavity RF system, which deteriorates the precision and increases the time needed for phase measurement with this technique. We analyze the influence of RF noise to the phase measurement in a simulation study with a beam-cavity model. Beam signal measurement with the cavity Low Level RF (LLRF) system and the initial experiment of prototype detectors are briefly introduced.

• Y. Zhang
  
• M. S. Champion, P. Chu, S. M. Cousineau, V. V. Danilov, T. W. Hardek, J. A. Holmes, H. Ma, M. F. Piller, M. A. Plum
  ORNL, Oak Ridge, Tennessee

A simulation code has been developed for the study of the Spallation Neutron Source (SNS) ring RF control. The code uses the time-domain solvers to compute beam-cavity interactions, and FFT methods to simulate time responses of the linear RF system. The important ingredients of the system are considered in the simulation model, which include the beam loading, dynamic cavity detuning, circuit bandwidth, loop delay, proportional-integral (P-I) controller for feedback and adaptive feed forward, stochastic noise, with-in-turn RF parameter change, beam current fluctuation and beam bunch leakage, etc. The beam loss in the accumulation ring goes up as the beam power increases, and thus a precise control of bunching voltage phase and amplitude is required to limit beam loss. This simulation tool will help the development a correct RF control and to achieve the goal of minimizing the beam loss.

• J. K. Keung
  
• N. Lockyer
  TRIUMF, Vancouver
• S. Nagaitsev
  Fermilab, Batavia, Illinois
• F. M. Newcomer
  University of Pennsylvania, Philadelphia, Pennsylvania

http://einstein.hep.upenn.edu/~keungj/simulation.html

• C. Wilsen
  
• M. F. Kirshner, R. D. Kowalczyk
  L-3, Williamsport, Pennsylvania

* M. F. Kirshner et al., "Apparatus and method for trajectory modulation of an electron beam," U. S. Provisional Patent Application 60/838,580, August 17, 2006. Cleared by DoD/OFOISR for public release under 07-S-0493 on January 22, 2007

• M. A. Kempkes
  
• F. O. Arntz, J. A. Casey, M. P.J. Gaudreau, I. Roth
  Diversified Technologies, Inc., Bedford, Massachusetts

• T. A. Treado
  
• S. J. Einarson
  CPI, Beverley, Massachusetts

• K. Hayashi
  
• M. Irikura, Y. Mitsunaka, Y. Okubo, M. Sakamoto, H. Taoka, K. Tetsuka, H. Urakata
  TETD, Otawara
• M. Y. Miyake, Y. Yano
  Toshiba, Yokohama

• H. Mori
  
• M. Akemoto, S. Fukuda, H. Honma, H. Nakajima, T. Shidara
  KEK, Ibaraki
• K. Furuya
  Nichicon (Kusatsu) Corporation, Shiga

• M. Wilcox
  

• T. Kato
  
• A. Tamura
  Nikken Sekkei Civil Ltd, Tokyo

• J. Yoshida
  
• K. Hara, K. Hosoyama, Y. Kojima, H. Nakai, K. Nakanishi
  KEK, Ibaraki
• T. Ichitani, S. Kaneda
  Taiyo Nippon Sanso Corporation, Kawasaki-city Kanagawa Pref.
• T. Kanekiyo
  Hitachi Technologies and Services Co., Ltd., Kandatsu, Tsuchiura
• M. Noguchi
  Mayekawa MFG. Co., Ltd., Moriya
• S. Sakuma, K. Suzuki
  Taiyo Nippon Sanso Higashikanto Corporation, Hitachi-shi, Ibaraki-Perf.

• U. Emanuele, U. Emanuele, A. Italiano
  INFN - Gruppo Messina, S. Agata, Messina
• L. Auditore, R. C. Barna, D. De Pasquale, D. Loria, A. Trifiro, M. Trimarchi
  Universita di Messina, Messina

• L. Monaco
  
• J. W. Baehr, M. Krasilnikov, S. Lederer, F. Stephan
  DESY Zeuthen, Zeuthen
• J. H. Han, S. Schreiber
  DESY, Hamburg
• P. Michelato, C. Pagani, D. Sertore
  INFN/LASA, Segrate (MI)

The FLASH (DESY-Hamburg) and PITZ (DESY-Zeuthen) photoinjectors routinely use high quantum efficiency (QE) photocathodes produced at LASA (INFN-Milano), since 1998. To further understand the photocathode behavior during beam operation, photocathode QE measurements have been performed at different operating conditions in both RF photoinjectors. The analysis of these measurements will be used to improve the photocathode preparation procedures and to deeper understand the photocathode properties, whose final goal would be the further increase of their lifetime and beam quality preservation during the RF gun operations.

• S. H. Kim
  
• M.-H. Cho, W. Namkung, H. R. Yang
  POSTECH, Pohang, Kyungbuk
• S. D. Jang, S. J. Kwon, J.-S. Oh, S. J. Park, Y. G. Son
  PAL, Pohang, Kyungbuk

An intense L-band electron accelerator is designed and under development for CESC (Cheorwon Electron-beam Service Center) irradiation applications. It is capable of producing 10-MeV electron beams with average 30 kW. For an RF source, a Thales klystron is used with 1.3 GHz, pulsed 25 MW, and average 60 kW. The accelerator column, fabricated by IHEP in China, is operated with 2π/3 mode traveling-wave under the fully-beam-loaded condition. The modulator was fabricated with inverter power supplies. The klystron was assembled to the klystron tank with pulse transformer. The high-voltage pulse test was conducted for the klystron tube. In this paper, we present design details of the accelerator and current status.

• M. Church
  
• A. Z. Chen, N. V. Mokhov, S. Nagaitsev, N. Nakao
  Fermilab, Batavia, Illinois

• M. Church
  
• S. Nagaitsev, P. Piot
  Fermilab, Batavia, Illinois

• F. W. Meyer
  
• M. R. Fogle, J. W. Hale
  ORNL, Oak Ridge, Tennessee

We report on the development and implementation of a new beam line floatable at up to -15 kV and injected by a 10 GHz CAPRICE ECR ion source at the ORNL Multicharged Ion Research Facility MIRF as part of a major facility upgrade project [1]. With the floating beamline operating at negative high voltage, and the ECR source at ground potential, intense dc beam deceleration into grounded experimental chambers to energies as low as a few eV/q is made possible. The primary application of these ion beams is to study fundamental collisional interactions [2] of multicharged ions with electrons, atoms, and surfaces. Design details of the floating beam line, including source extraction, deceleration optics and voltage isolation will be presented at the conference. The novel features of a LABVIEW-based supervisory control and data acquisition (SCADA) system developed for the floating beam line will be described as well.

[1]F. W. Meyer et al. "The ORNL MIRF Upgrade project," NIMB B242,71(2006).[2]F. W. Meyer,"ECR-Based Atomic Collisions Research at ORNL MIRF," in Trapping Highly Charged Ions: Fundamentals & Applications, Nova Sci. Pub., New York, 2000, pp. 117-164.

• P. V. Avrakhov
  
• N. Solyak
  Fermilab, Batavia, Illinois

• A. Kanareykin
  
• M. E. Conde, W. Gai
  ANL, Argonne, Illinois
• R. Gat
  Coating Technology Solution, Inc., Somerville
• C.-J. Jing, P. Schoessow
  Euclid TechLabs, LLC, Solon, Ohio

In this talk, we present our recent developments on a high gradient diamond-based cylindrical dielectric loaded accelerator (DLA). The final goal of this research is to achieve a record accelerating gradient (~ 600 MV/m) in a demonstration of the structure at high power and with accelerated beam. We discuss here a new technology for the development of cylindrical diamond-based waveguides and the design, fabrication and high power testing of a cylindrical diamond-based DLA accelerating structure. 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 thermoconductive coefficient available. Multipacting of the CVD diamond can be suppressed by diamond surface dehydrogenation. A plasma supported Chemical Vapor Deposition (CVD) technology to produce low loss high quality cylindrical diamond layers is presented. Special attention is devoted to the numerical optimization of the coupling section, where the surface magnetic and electric fields are minimized relative to the accelerating gradient and within known metal surface breakdown limits.

• P. Schoessow
  
• A. Kanareykin
  Euclid TechLabs, LLC, Solon, Ohio
• V. P. Yakovlev
  Omega-P, Inc., New Haven, Connecticut

New low loss ferroelectric ceramic materials* possessing large variations in the permittivity as a function of the electric field present interesting and potentially useful applications for dielectric loaded accelerating structures, both wakefield-based and driven by an external rf source. We will consider X-band cylindrical dielectric structures and report numerical results on frequency multiplication, wave steepening and shock formation, and the effect of nonlinearities on the mode structure of these devices. We will examine applications of nonlinear dielectric devices to high gradient acceleration, rf sources, and beam diagnostics.

* ''Fast Switching Ferroelectric Materials for Accelerator Applications'', A. Kanareykin et al., Proceedings of Advanced Accelerator Concepts 2006 (in press)

• S. H. Gold
  
• W. Gai, R. Konecny, J. Long, J. G. Power
  ANL, Argonne, Illinois
• C.-J. Jing
  Euclid TechLabs, LLC, Solon, Ohio
• A. K. Kinkead
  LET
• C. D. Nantista, S. G. Tantawi
  SLAC, Menlo Park, California

A joint project is underway by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a compact X-band accelerator for testing dielectric-loaded accelerator (DLA) structures.* The accelerator will use a 5-MeV injector previously developed by the Tsinghua University in Beijing, China, and will accommodate test structures up to 0.5 m in length. Both the injector and the structures will be powered by an 11.4-GHz magnicon amplifier that can produce 25 MW, 200-ns output pulses at up to 10 Hz. The injector will require ~5 MW of rf power, leaving ~20 MW to power the test structures. This paper will present a progress report on the construction and commissioning of the test accelerator, which will be located in a concrete bunker in the Magnicon Facility at NRL.

* S. H. Gold et al., Proc. PAC 2005.

• A. Baartman
  
• D. Kaltchev
  TRIUMF, Vancouver

• H. Ohgaki
  
• Y. Iwasaki, T. Tomimasu
  SAGA, Tosu
• S. Koda, Y. Takabayashi, K. Yoshida
  Saga Synchrotron Light Source, Industry Promotion Division, Saga City

• B. Qin
  
• M. Fan, Y. Q. Xiong, Y. Xu, J. Yang
  HUST, Wuhan

An intelligent magnet design, modelling and optimization method with the aid of beam dynamics analysis and three dimensional magnetic field calculation is introduced. The whole procedure is implemented in an integrated virtual prototyping environment built with python language. As a case study, the main magnet design of a 16MeV H^- compact cyclotron is illustrated. Both the field isochronism and transversal focusing of the beam can be fulfilled, and the mechanical analysis is performed to validate the feasibility in mechanics.

• F. Schmidt
  
• E. Forest
  KEK, Ibaraki
• P. K. Skowronski
  CERN, Geneva

• F. Schmidt
  
• I. V. Agapov
  DESY, Hamburg
• W. Herr, G. Kruk, M. Lamont
  CERN, Geneva

• B. Sayyar-Rodsari
  
• E. Hartman, C. A. Schweiger
  Pavilion Technologies, Inc, Austin, Texas
• M. J. Lee, P. Lui, J. M. Paterson, J. F. Schmerge
  SLAC, Menlo Park, California

High brightness electron beam sources such as rf photo-injectors as proposed for SASE FELs must consistently produce the desired beam quality. We report the results of a study in which a combined neural network (NN) and first-principles (FP) model is used to model the transverse phase space of the beam as a function of quadrupole magnet current, while beam charge, solenoid field, accelerator gradient, and linac voltage and phase are kept constant. The parametric transport matrix between the exit of the linac section and the spectrometer screen constitutes the FP component of the combined model. The NN block provides the parameters of the transport matrix as functions of quad current. Using real data from SLAC Gun Test Facility, we will highlight the significance of the constrained training of the NN block and show that the phase space of the beam is accurately modelled by the combined NN and FP model, while variations of beam matrix parameters with the quad current are correctly captured. We plan to extend the combined model in the future to capture the effects of variations in beam charge, solenoid field, and accelerator voltage and phase.

• B. W. Buckley
  
• G. Hoffstaetter
  CLASSE, Ithaca

One of the main concerns in the design of a high energy Energy Recovery Linac x-ray source is the preservation of beam emittance. Discussed is one possible source of emittance dilution due to transverse electromagnetic fields in the accelerating cavities of the linac caused by the power coupler geometry. This has already been found to be a significant effect in Cornell's ERL injector cavities if only one coupler per cavity is chosen. Here we present results of simulations for Cornell's main ERL linac with three possible coupler configurations and compare them with regards to total normalized emittance growth after one complete pass through the linac. We explain why the sign of the phase between the transverse kick and the accelerating force alternates each cavity, which leads to a cancellation of the emittance growth to acceptable values. We also investigate the effect of cavity detuning on the coupler-kick effect.

• J. F. DeFord
  
• B. Held
  STAR, Inc., Mequon, Wisconsin
• J. J. Petillo
  SAIC, Burlington, Massachusetts

Particle orbit errors in multipacting and dark current computations can arise from inadequate field representation, poor surface modeling, and from the integration algorithm used to advance the particles. Established fields-based adaptive mesh refinement (AMR) methods *,** selectively improve the field and surface representation over several iterations in finite-element codes but they are not optimized for particle tracking. In particular, field emission and secondary emission models require precise surface representations and highly accurate field representations near surfaces, and these requirements are not adequately addressed in standard AMR techniques. In this paper we report on extensions to existing AMR support in the Analyst software package for particle tracking, including adaptive improvement of near-surface and on-surface field representations, and control of element aspect ratios throughout successive iterations. We also discuss the merits of automated identification of important regions of the mesh based on field levels and orbit estimation to guide AMR in multipacting calculations, and multipacting results for a SRF cavity will be presented.

* G. Drago, et al., IEEE Trans. on Mag., 28, 1992, pp. 1743-1746.** D. K. Sun, et al., IEEE Trans. on Mag., 36, July 2000, pp. 1596-1599.

• L. Wang
  

Grooved surface is proposed to reduce the secondary emission yield in a dipole and wiggler magnet of International Linear Collider. An analysis of the impedance of the grooved surface based on adaptive finite element is presented in this paper. The performance of the adaptive algorithms, based on an element-element h-refinement technique, is assessed. The features of the refinement indictors, adaptation criteria and error estimation parameters are discussed.

• R. M. Bodenstein
  
• M. G. Tiefenback
  Jefferson Lab, Newport News, Virginia

The CEBAF recirculating accelerator consists of two CW superconducting RF linacs, through which an electron beam is accelerated for up to 5 passes. Focusing and steering elements affect each pass differently, requiring a multipass steering protocol to correct the orbits. Perturbations include lens misalignments (including long-term ground motion), BPM offsets, and focusing and steering from RF fields inside the cavities. A previous treatment of this problem assumed all perturbations were localized at the quadrupoles and the absence of x-y coupling. Having analyzed the problem and characterized the solutions, we developed an empirical iterative protocol to compare against previous results in the presence of skew fields and cross-plane coupling. We plan to characterize static and acceleration-dependent components of the beam line perturbations to allow systematic and rapid configuration of the accelerator at different linac energy gains.

• D. Douglas
  
• K. Beard, J. Eldred, P. Evtushenko, A. Jenkins, S. W. Moore, L. Osborne, D. W. Sexton, C. Tennant
  Jefferson Lab, Newport News, Virginia

Particle beam modeling in accelerators has been the focus of much effort (at great expense) since the 1950s. Several generations of tools have resulted from this process, each leveraging both the understanding provided by predecessors and the availability of increasingly powerful computer hardware. Nonetheless, the process remains on-going, in part due to innovations in accelerator design, construction, and operation that result in machines not easily described by existing tools. We discuss a novel response to this issue, which was encountered when Jefferson Lab began operation of its energy-recovering linacs. As such machines are not conveniently described using legacy software, a machine model was been built using Microsoft Excel. This interactive simulation can query data from the accelerator, use it to compute machine parameters, analyze difference orbit data, and evaluate beam properties. It can also derive new accelerator tunings and rapidly evaluate the impact of changes in machine configuration. As it is spreadsheet-based, it can be easily user-modified in response to changing requirements. Examples for the JLab IR Upgrade FEL are presented.

• N. Barov
  
• S. Reiche
  UCLA, Los Angeles, California

Many simulation efforts make use of integrated numerical experiments, where the inputs and outputs of several accelerator codes are tied together. This is usually accomplished by writing custom scripts that launch the underlying programs and perform data format translation. We present a way to simplify this process by using a graphical user interface that allows one to describe the data flow in the style of the LabVIEW and Simulink environments. A module to support a new accelerator code involves writing data translators to/from a common format (SDDS or HDF5), and a function to generate an input file based on a standard way of specifying an accelerator lattice (such as Accelerator Markup Language, or AML).

• M. S. Champion
  

• T. W. Hardek
  
• M. S. Champion, M. T. Crofford, H. Ma, M. F. Piller
  ORNL, Oak Ridge, Tennessee
• K. Smith, A. Zaltsman
  BNL, Upton, Long Island, New York

The Spallation Neutron Source (SNS) accumulator ring is a fixed-frequency proton storage ring located at the output of the SNS Linear Accelerator (Linac). Its purpose is to convert 1 millisecond H^- beam pulses from the SNS Linac into high-intensity 695 nanosecond pulses of protons for delivery to the neutron target. The RF bunching system controls longitudinal beam distribution during the accumulation process and maintains a 250+ nanosecond gap required for beam extraction. The RF system consists of three stations which operate at a beam revolution frequency of 1.05 MHz while a fourth station provides a second harmonic component at 2.1 MHz. The beam pulse at extraction consists of 1.6·10¹⁴ protons representing a peak beam current of 52 amperes. The system utilizes four 600kW tetrodes to provide the RF current necessary to produce the 40kV peak-bunching voltage and to control phase and amplitude at this high beam current. In this paper we review the design concepts incorporated into this heavily beam-loaded RF system and discuss its commissioning status.

• I. V. Bylinskii
  
• K. Fong, J. Lu, A. K. Mitra, C. Owen
  TRIUMF, Vancouver

• R. B. Wilcox
  
• J. W. Staples
  LBNL, Berkeley, California

Development of accelerator-based light sources is expanding the size of femtosecond laser systems from tabletop devices up to kilometer-scale facilities. New optical techniques are needed to maintain temporal stability in these large systems. We present methods for distributing timing information over optical fiber using continuous optical waves, and how these can be employed in advanced accelerators requiring less than 100fs timing stability. Different techniques combine to form a tool set that can provide for synchronization down to a few femtoseconds. Practical examples are given for timing systems applicable to FELs now under construction, with experimental results to show these systems can be built with required performance. For example, have demonstrated 2km fiber links with 5fs timing stability over 24 hours, and synchronized femtosecond lasers separated by a fiber link with 20fs RMS relative jitter.

• J. Branlard
  
• B. Chase
  Fermilab, Batavia, Illinois
• S. Michizono
  KEK, Ibaraki
• S. Simrock
  DESY, Hamburg

The key to a successful LLRF design for the International Linear Collider (ILC) relies on a combined effort from the different laboratories involved in this global project. This paper covers the ILC LLRF design progress both long term and for current test facilities around the world. Much of the focus is towards the ILC Test Area and on inter-laboratories collaborations. The SIMCON controller board, originally developed at DESY has been successfully used at FNAL to control the superconducting capture cavity I and II. A joined effort is also underway to modify its hardware to improve its noise performance and upgrading the firmware to achieve a higher intermediate frequency operation. In parallel, several simulation models (U-Penn, FNAL) have been developed in addition to the Simulink based model from DESY. The motivation is to investigate such issues as variable gradients, low beam conditions and bunch compression. Finally, an active exchange of knowledge and expertise continues to occur during collaboration meetings and through mutual participation in accelerator tests and commissioning (Dec06/Jan07 at DESY).

• B. Brajuskovic
  
• J. T. Collins, P. K. Den Hartog, L. H. Morrison, G. J. Waldschmidt
  ANL, Argonne, Illinois

A normal-conducting deflecting cavity is being designed at the Advanced Photon Source (APS) as a part of the short x-ray pulse project intended to provide users with approximately 2 picosecond x-rays. The system will use two pairs of 3-cell cavities in sectors 6ID and 7ID for the generation of the x-ray pulse in the 7ID beamline. The 3-cell cavities are designed to provide the desired beam deflection while absorbing in excess of 4 kW of power from a pulsed rf system and up to 2.6 kW in the damper system of high-order mode (HOM) and low-order mode (LOM) waveguides. Since the cavity frequency is very sensitive to thermal expansion, the cooling water system is designed so that it is able to control cavity temperature to within 0.1?C. This paper describes the optimization of the thermomechanical design of the cavity based on calculation of thermal stresses and displacement caused by the generated heat loads, and presents the design of a cooling water system required for the proper operation of the cavities.

• T. Kobayashi
  

• W. R. Flavell
  

* e.g. J Andruszkow et al., Phys. Rev. Lett., 85, 3825, (2000).**e.g. G. R. Neil et al., Phys. Rev. Lett. 84, 662, (2000).*** e.g. H Wabnitz et al., Nature, 420, 467, (2002), T Laarmann et al., Phys. Rev. Lett., 95, 063402 (2005)

• L. Ficcadenti
  
• D. Alesini, G. Di Pirro, C. Vaccarezza
  INFN/LNF, Frascati (Roma)
• A. Mostacci, L. Palumbo
  Rome University La Sapienza, Roma
• J. B. Rosenzweig
  UCLA, Los Angeles, California

This work has been partially supported by the EU in the sixth framework program, Contract no. 011935 EUROFEL-DS1.

• T. Fujita
  
• S. Sasaki, M. Shoji, T. Takashima
  JASRI/SPring-8, Hyogo-ken

• K. Satou
  
• N. Hayashi, H. Hotchi, Y. Irie, M. Kinsho, M. Kuramochi, P. K. Saha, Y. Yamazaki
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• S. Lee
  KEK, Ibaraki

• S. H. Shin
  
• Y. Honda, J. Urakawa
  KEK, Ibaraki
• E.-S. Kim, H.-S. Kim
  Kyungpook National University, Daegu

• H.-J. Kwon
  
• Y.-S. Cho, I.-S. Hong, J.-H. Jang, D. I. Kim, H. S. Kim, K. T. Seol
  KAERI, Daejon

The beam test of the Proton Engineering Frontier Project (PEFP) 20 MeV proton linear accelerator started again, after the upgrade of the RF control system, One of the important goals of the test is to increase the beam current to the design level. Tuned current transformers were installed along the DTL tanks to measure the beam current itself and possible beam loss along the accelerator. Because there were no empty drift tubes, the current transformers should be installed between DTL tanks. Therefore, the tuning plans were developed to obtain the desired beam properties with the limited number of beam diagnostic devices. Also two BPMs for the time of flight measurement and energy degrader were installed at the end of the 20 MeV accelerator to measure the beam energy. In this paper, the overall test results including beam current and energy measurement are presented.

• A. Boccardi
  
• M. Gasior, O. R. Jones, K. K. Kasinski, R. J. Steinhagen
  CERN, Geneva

• J. Chen
  
• P. C. Chiu, K. T. Hsu, S. Y. Hsu, K. H. Hu, C. H. Kuo, D. Lee, C.-J. Wang, C. Y. Wu
  NSRRC, Hsinchu

• K. H. Hu
  
• K. T. Hsu, J.-Y. Hwang, D. Lee, K.-K. Lin, C. Y. Wu
  NSRRC, Hsinchu

• K. H. Hu
  
• J. Chen, K. T. Hsu, C. H. Kuo, C. Y. Wu
  NSRRC, Hsinchu

• C. H. Kuo
  
• J. Chen, K. T. Hsu, S. Y. Hsu, K. H. Hu, D. Lee, C.-J. Wang, C. Y. Wu
  NSRRC, Hsinchu

• C. H. Kuo
  
• J. Chen, P. C. Chiu, K. T. Hsu, K. H. Hu
  NSRRC, Hsinchu

• M. R.W. North
  

• S. R. Babel
  

High voltage power modules find uses in many applications like the Photo multiplier Tubes (PMT), Ionization chambers, CRT systems testing, high voltage biasing for Avalanche Photodiodes, Photo detectors, X-ray tubes, Pulse generators which are used in radars, lasers, EMC testing and other imaging applications. Providing high voltage, to these applications, which can be remotely controlled in a small, confined area, is a problem many laboratories around the world face. The LV and the HV series of high voltage systems from BiRa Systems present experimenters with voltages ranging from several hundreds upto ± 5kV in a rugged CompactPCI / PXI chassis, running National Instruments' LabView. The CompactPCI architecture offers modularity, tight integration and low cost. Apart from that, the deterministic and real time nature of the operating system also allows these modules to be remotely controlled and monitored over the Ethernet. The high voltage cards can be easily custom tailored to a particular voltage and current requirement

• W. E. Norum
  
• B. X. Yang
  ANL, Argonne, Illinois

Bunch purity is an important source quality factor for the magnetic resonance experiments at the Advanced Photon Source. Conventional bunch-purity monitors utilizing time-to-amplitude converters are subject to dead time. We present a novel design based on a single field-programmable gate array (FPGA) that continuously processes pulses at the full speed of the detector and front-end electronics. The FPGA provides 7778 single-channel analyzers (six per RF bucket). The starting time and width of each single-channel analyzer window can be set to a resolution of 178 ps. A detector pulse arriving inside the window of a single-channel analyzer is recorded in an associated 32-bit counter. The analyzer makes no contribution to the system dead time. Two channels for each RF bucket count pulses originating from the electrons in the bucket. The other four channels on the early and late side of the bucket provide estimates of the background. A single-chip microcontroller attached to the FPGA acts as an EPICS IOC to make the information in the FPGA available to the EPICS clients.

• A. Pietryla
  
• H. Bui, G. Decker, R. Laird, R. M. Lill, W. E. Norum
  ANL, Argonne, Illinois

The Advanced Photon Source (APS), a third-generation synchrotron light source, has been in operation for twelve years. The monopulse radio frequency (rf) beam position monitor (BPM) is one of three BPM types now employed in the storage ring at the APS. It is a broadband (10 MHz) system designed to measure single-turn and multi-turn beam positions, but it suffers from an aging data acquisition system. The replacement BPM system retains the existing monopulse receivers and replaces the data acquisition system with high-speed analog-to-digital converters (ADCs) and a field-programmable gate array (FPGA) that performs the signal processing. A first article system has been constructed and is currently being evaluated. This paper presents the results of testing of the first article system as well as the progress made in other areas of this upgrade effort.

• S. E. Shoaf
  

A real-time image analysis system was developed for beam imaging diagnostics. An Apple Power Mac G5 with an Active Silicon LFG frame grabber were used to capture video images that were processed and analyzed. Software routines were created to utilize vector processing hardware to reduce the time to process images as compared to conventional methods. These improvements allow for more advanced image processing diagnostics to be performed in real time.

• X. Sun
  
• O. Singh
  ANL, Argonne, Illinois

The Advanced Photon Source storage ring employs a real-time orbit correction system to reduce orbit motion up to 50 Hz. This system uses up to 142 narrow-band rf beam position monitors (Nbbpms) in a correction algorithm by sampling at a frequency of 1.53 kHz. Several Nbbpms exhibit aliasing errors in orbit measurements, rendering these Nbbpms unusable in real-time orbit feedback. The aliasing errors are caused by beating effects of the internal sampling clocks with various other processing clocks residing within the BPM electronics. A programmable external clock has been employed to move the aliasing errors out of the active frequency band of the real-time feedback system (RTFB) and rms beam motion calculation. This paper discusses the process of tuning and provides test results.

• C.-Y. Tan
  

In the classical chromaticity measurement technique, chromaticity is measured by measuring the change in betatron tune as the the RF frequency is varied. This paper will describe a way of measuring chromaticity: we will phase modulate the RF with a known sine wave and then phase demodulate the betatron frequency . The result is a line in Fourier space which corresponds to the frequency of our sine wave modulation. The peak of this sine wave is proportional to chromaticity. For this technique to work, a tune tracker PLL system is required because it supplies the betatron carrier frequency. This method has been tested in both the SPS and Tevatron and we will show the results here.

• J. M. Weber
  
• M. J. Chin, CA. Timossi, E. C. Williams
  LBNL, Berkeley, California

The ALS booster magnet upgrade for top off operation requires new instrumentation to meet increased magnet ramping requirements. To address these requirements, the ALS Instrumentation and Controls groups collaborated to design a new control system module called the Mini IOC. The Mini IOC hardware is based on a commercial evaluation board containing an FPGA with embedded processor and built-in interfaces for 128MB of DDR SDRAM and Ethernet. A custom module is used for analog controls and monitors. The PowerPC embedded processor runs an EPICS database built on the VxWorks operating system allowing remote access via Ethernet. This paper includes an overview of the Mini IOC design and operational results.

• A. S. Fisher
  
• S. Ecklund, R. C. Field, S. M. Gierman, P. Grossberg, K. E. Krauter, E. S. Miller, M. Petree, N. Spencer, M. K. Sullivan, K. K. Underwood, U. Wienands
  SLAC, Menlo Park, California
• K. G. Sonnad
  LBNL, Berkeley, California

To maximize luminosity, a feedback system adjusts the relative transverse (x,y) position and vertical angle (y') of the electron and positron beams at the interaction point (IP) of PEP-II. The original system sequentially moved ("dithered") the electrons in four steps per coordinate. Communication with DC corrector magnets and field penetration through copper vacuum chambers led to a full-cycle time of 10 s. Machine tuning can move the beams at the IP and so had to be slowed to wait for the feedback. A new system installed in 2006 simultaneously applies a small sinusoidal dither to all three coordinates at 73, 87 and 103 Hz. Air-core coils around stainless-steel chambers give rapid field penetration. A lock-in amplifier at each frequency detects the magnitude and phase of the luminosity's response. Then corrections for all coordinates are determined using Newton's method, based on convergence from prior steps, and are applied by the same DC correctors used previously but with only one adjustment per cycle for an expected ten-fold increase in speed. We report on the commissioning of this system and on its performance in maintaining peak luminosity and aiding machine tuning.

• C. Mcguinness
  
• R. L. Byer, T. Plettner
  Stanford University, Stanford, Califormia
• E. R. Colby, R. Ischebeck, R. J. Noble, C. M.S. Sears, R. Siemann, J. E. Spencer, D. R. Walz
  SLAC, Menlo Park, California

The laser acceleration experiments conducted for the E163 project at the NLC Test Accelerator facility at SLAC have stringent requirements on the temporal properties of the electron and laser beams. A system has been implemented to measure the relative phase stability between the RF sent to the gun, the RF sent to the accelerator, and the laser used to generate the electrons. This system shows rms timing stability better than 1 psec. Temporal synchronicity between the 0.5 psec electron bunch, and the 0.5 psec laser pulse is also of great importance. Cherenkov radiation is used to measure the arrival time of the electron bunch with respect to the laser pulse, and the path length of the laser transport is adjusted to optimize temporal overlap. A linear stage mounted onto a voice coil is used to make shot-by-shot fine timing adjustments to the laser path. The final verification of the desired time stability and control is demonstrated by observing the peak of the laser-electron interaction signal over the course of several minutes.

• S. Molloy
  
• C. D. Beard, J.-L. Fernandez-Hernando
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• A. Bungau
  UMAN, Manchester
• S. Seletskiy, M. Woods
  SLAC, Menlo Park, California
• J. D.A. Smith
  Cockcroft Institute, Warrington, Cheshire
• A. Sopczak
  Lancaster University, Lancaster
• N. K. Watson
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

We report on measurements of the transverse wakefields induced by collimators of differing characteristics. An apparatus allowing the insertion of different collimator jaws into the path of a beam was installed in End Station A (ESA) in SLAC. Eight comparable collimator geometries were designed, including one that would allow easy comparison with previous results, and were installed in this apparatus. Measurements of the beam kick due to the collimator wakefields were made with a beam energy of 28.5 GeV, and beam dimensions of ~100 microns vertically and a range of 0.5 to 1.5 mm longitudinally. The trajectory of the beam upstream and downstream of the collimator test apparatus was determined from the outputs of ten BPMs (four upstream and six downstream), thus allowing a measurement of the angular kick imparted to the beam by the collimator under test. The transverse wakefield was inferred from the measured kick. The different aperture designs, data collection and analysis, and initial comparison to theoretical and analytic predictions are presented here.

* "An Apparatus for the Direct Measurement of Collimator Transverse Wakefields", P. Tenenbaum, PAC '99** "Direct Measurement of the Resistive Wakefield in Tapered Collimators", P Tenenbaum, PAC '04

• W. Wittmer
  
• A. S. Fisher, D. J. Martin, J. J. Sebek
  SLAC, Menlo Park, California

During the last PEP-II run a major goal was to bring the Low-Energy Ring optics as close as possible to the design. Sudden artificial jumps of the orbit, which were regularly observed by a large number of BPMs during routine operation, were interfering with this effort. The source of the majority of these jumps had been traced to the filter-isolator boxes (FIBs) near the BPM buttons. A systematic approach to find and repair the failing units had been developed and implemented. Despite this effort, the instrumental orbit jumps never completely disappeared. To trace the source of this behavior a test setup, using a spare Bergoz MX-BPM processor (kindly provided by SPEAR III at SSRL) was connected in parallel to various PEP-II BPM processors. In the course of these measurements a slow instrumental orbit drift was found which was clearly not induced by a moving positron beam. Based on the size of the system and the limited time before the end of PEP II an accelerator improvement project was initiated to install BERGOZ BPM-MX processors close to all sextupoles.

• A. Kanareykin
  
• W. Gai, J. G. Power
  ANL, Argonne, Illinois
• C.-J. Jing, A. L. Kustov, P. Schoessow
  Euclid TechLabs, LLC, Solon, Ohio

We report on the experimental and numerical investigation of beam breakup (BBU) effects in dielectric structures resulting from parasitic wakefields. The experimental program focuses on measurements of BBU in a number of wakefield devices: (a) a 26 GHz power extraction structure; (b) a high gradient dielectric wakefield accelerator; (c) a wakefield structure driven by a high current ramped bunch train for multibunch BBU studies. New beam diagnostics will provide methods for studying parasitic wakefields that are currently unavailable at the AWA facility. The numerical part of this research is based on a particle-Green's function based beam breakup code we are developing that allows rapid, efficient simulation of beam breakup effects in advanced linear accelerators. The goal of this work is to be able to compare the accurate numerical results obtained from the new BBU code with the results of the detailed experimental measurements. An external focusing system for the control of the beam in the presence of strong transverse wakefields is considered.

• J. Bengtsson
  

In earlier work related to the NSLS-II project we have outlined a control theory approach for the dynamic aperture problem. In particular, an algorithm for the joint optimization of the Lie generator and the working point for the Poincare map. This time we report on how the Lie generator provides guidelines on acceptable magnitudes for e.g. the intrinsic nonlinear effects from insertion devices, and the nonlinear pseudo-invariant can be used to optimize the dynamic aperture. We also show how a polymorphic beam line class can be used to study the parameter dependance and rank conditions for control of optics and dynamic aperture.

bengtsson@bnl.gov

• C. Montag
  
• J. Bengtsson, B. Nash
  BNL, Upton, Long Island, New York