TESLA

Paper	Title	Other Keywords	Page
MOPCH065	Fabrication and Installation of Superconducting Accelerator Modules for the ERL Prototype (ERLP) at Daresbury	vacuum, cryogenics, ERLP, linac	178
	P. vom Stein, S. Bauer, M. Pekeler, H. Vogel ACCEL, Bergisch Gladbach R. Bate, C.D. Beard, D.M. Dykes, P.A. McIntosh, B. Todd CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	Installation and commissioning of the superconducting energy recovery linac(ERL) prototype is under way at Daresbury Laboratory. ACCEL have manufactured two superconducting accelerator modules for the injector and the linac, operating at 2K with 1.3 GHz TESLA type cavities. Each module contains two cavities and is designed to provide an accelerating voltage of 25 MV in cw mode. This paper presents details of the module fabrication, cavity preparation and performance results. An overview of the cryogenic installations for the modules is given and status results of the commissioning are discussed.
MOPCH144	Low Temperature Properties of Piezoelectric Actuators Used in SRF Cavities Cold Tuning Systems	radiation, target, cyclotron, LHC	390
	G. Martinet, S. Blivet, F. Chatelet, M. Fouaidy, N. Hammoudi, A. Olivier, H. Saugnac IPN, Orsay
	High accelerating gradients (10 MV/m for SNS, 33 MV/m for ILC) at which SRF cavities will be operated in pulsed machines induce frequency shift much higher than the resonator bandwidth. This so-called Lorentz detuning should be compensated dynamically by means of an active piezo-tuning system. In the frame of the CARE project activities supported by EU, IPN Orsay participates to the development of a fast cold tuning system based and piezoelectric technology for SRF cavities operating at temperature T=2K. The aim of this study is the full characterization of piezoelectric actuators at low temperature including dielectric properties (capacitance, impedance, dielectric losses), radiation hardness tests (fast neutron tolerance), mechanical measurements (maximum displacement, maximum stroke) and thermal properties (heating, heat capacity). Results obtained in the temperature range from 2K up to 300K will be presented and discussed.
MOPCH148	First RF Tests in the HoBiCaT Superconducting Test Facility at BESSY	vacuum, cryogenics, electron, controls	402
	O. Kugeler, W. Anders, J. Borninkhof, H.G. Hoberg, S. Klauke, J. Knobloch, M. Martin, G. Mielczarek, A. Neumann, D. Pflückhahn, S. Rotterdam, M. Schuster, T. Westphal BESSY GmbH, Berlin
	In preparation for the construction of the BESSY-FEL User Facility, BESSY recently completed the installation of the HoBiCaT cryogenic test facility for superconducting RF (SRF) TESLA cavity units, including all ancillary devices (helium tank, input coupler, tuner, magnetic shielding). It is designed to house two such units in a configuration similar to that envisaged for the superconducting CW linac of the BESSY FEL. Commissioning of the facility is now complete and the first TTF-III RF coupler and cavity unit have been tested. In particular, the complete production, cleaning and assembly of the cavity unit was carried out by industry. These tests thus serve as a first step at qualifying industrial partners for series production of such systems, which will be essential for the future construction of SRF based light sources. Results will be presented.
MOPCH150	Characterization of a Piezo-based Microphonics Compensation System at HoBiCaT	resonance, controls, FEL, linac	408
	A. Neumann, W. Anders, S. Klauke, J. Knobloch, O. Kugeler, M. Schuster BESSY GmbH, Berlin
	In the superconducting driver linac for the BESSY FEL, piezo actuators will be utilized to rapidly counteract the detuning of the cavity resonance caused by nm mechanical oscillations (microphonics). This is of importance to guarantee field stability and lower the power consumption of the RF system for the superconducting cavities. To design a suitable compensator, mechanical and electro-mechanical transfer functions, as well as the tuning range of the system under operating conditions have been measured and will be presented.
MOPCH155	Performance Limitations of Tesla Cavities in the Flash Accelerator and their Relation to the Assembly Process	vacuum, DESY, pick-up, controls	421
	L. Lilje DESY, Hamburg
	Several accelerator modules with superconducting cavities have been assembled for TTF. The paper reviews the performance of these structures and will try to correlate their performance to information about the assembly process. In some cases a performace degradation could be attributed to problems in this process. The introduction of additional quality control steps improved accelerator module performance. For example, the more recently assembled modules have shown the expected acceleration gradients and no vacuum leaks.
MOPCH157	Structural Analysis for a Half-reentrant Superconducting Cavity	simulation, vacuum, linac, linear-collider	424
	E. Zaplatin FZJ, Jülich T.L. Grimm, W. Hartung, M. J. Johnson, M.S. Meidlinger, J. Popielarski NSCL, East Lansing, Michigan
	A half-reentrant cavity (1300 MHz, beta=1.0) is being developed at Michigan State University for use in a superconducting linear collider and other applications. The electromagnetic performance of a half-reentrant cell shape is similar to that of a fully reentrant cavity, but a multi-cell half-reentrant cavity can be cleaned using traditional techniques. We present the results of structural analyses of the half-reentrant cavity for the mid-cell, single-cell, and multi-cell cases. The analysis includes the static and dynamic response of the cavity. Stiffening options to minimize the resonant RF frequency shift due to pressure and the Lorentz force are explored.
MOPCH161	Development of a Prototype Superconducting CW Cavity and Cryomodule for Energy Recovery	ERL, linac, TTF, ERLP	436
	P.A. McIntosh, C.D. Beard, D.M. Dykes, B. Todd CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire S.A. Belomestnykh Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York A. Buechner, P. Michel, J. Teichert FZR, Dresden J.M. Byrd, J.N. Corlett, D. Li LBNL, Berkeley, California T. Kimura, T.I. Smith Stanford University, Stanford, Califormia M. Liepe, V. Medjidzade, H. Padamsee, J. Sears, V.D. Shemelin Cornell University, Ithaca, New York D. Proch DESY, Hamburg
	Energy Recovery LINAC (ERL) and LINAC-driven FEL proposals and developments are now widespread around the world. Superconducting RF (SRF) cavity advances made over the last 10 years for TESLA/TTF at 1.3 GHz, in reliably achieving accelerating gradients >20 MV/m, suggest their suitability for these ERL and FEL accelerators. Typically however, photon fluxes are maximised from the associated insertion devices when the electron bunch repetition rate is as high as possible, making CW-mode operation at high average current a fundamental requirement for these light sources. Challenges arise in controlling the substantial HOM power and in minimizing the power dissipated at cryogenic temperatures during acceleration and energy recovery, requiring novel techniques to be employed. This paper details a collaborative development for an advanced high-Qo cavity and cryomodule system, based on a modified TESLA cavity, housed in a Stanford/Rossendorf cryomodule. The cavity incorporates a Cornell developed resistive-wall HOM damping scheme, capable of providing the improved level of HOM damping and reduced thermal load required.
MOPCH163	Analysis of Wakefields in the ILC Crab Cavity	dipole, luminosity, quadrupole, simulation	442
	G. Burt, A.C. Dexter Microwave Research Group, Lancaster University, Lancaster C.D. Beard, P. Goudket CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire L. Bellantoni Fermilab, Batavia, Illinois R.M. Jones UMAN, Manchester
	The large crossing angle schemes of the ILC need a correction of bunch orientation at the IP in order to recover a luminosity loss of up to 80%. The orientation of bunches can be changed using a transverse deflecting cavity. The location of the crab cavity would be close to the final focus, and small deflections caused by wakefields in the cavities could cause misalignments of the bunches at the IP. Wakefields in the FNAL CKM cavities have been analysed and their effects studied in view of use as the ILC crab cavity. Numerical simulations have been performed to analyse the transverse wakepotentials of up to quadrupole order modes in this cavity and the effect upon bunches passing through this cavity. Trapped modes within the CKM cavity have been investigated. Perturbation tests of normal conducting models of this cavity have been launched to verify these results. The effect of the final focus quadrupole magnets on the deflection given to the bunch have also been calculated and used to calculate luminosity loss due to wakefields.
MOPCH169	High Pressure Rinsing Water Jet Characterization	LEFT, DIAMOND, linear-collider, collider	460
	D. Sertore, E. Cavaliere, M. Fusetti, P. Michelato, C. Pagani, P. Pierini INFN/LASA, Segrate (MI)
	High pressure rinsing is widely used as the final wet step in the high field superconducting cavities production. The interaction of an high speed ultra pure water jet with the niobium surface depends on various parameters such as water pressure, water throughput, treatment duration, cavity rotation speed, etc. In this paper we illustrate a simple technique for the characterization of water jet parameters based on the momentum transfer between the water jet and a load cell. The jet profile and its dependence on water pressure as well as the force exerted by the jet on the surface are easily measured. Moreover a portable apparatus has been set up and the information gathered in different laboratories will be used for a quantitative comparison of the different HPR systems. These measurements allow to study the correlation of the jet parameters with the effects (surface status, oxide formation, corrosion, etc) of the water interaction with the niobium surface. Furthermore a new analysis, based on the luminescence induced on transparent dielectric samples, is used for confirmation of the water jet structure.
MOPCH170	Experimental and Theoretical Analysis of the Tesla-like SRF Cavity Flanges	TTF, vacuum, cryogenics, collider	463
	L. Monaco, P. Michelato, C. Pagani, N. Panzeri INFN/LASA, Segrate (MI)
	In view of the future large SC accelerator, an improvement of the reliability and a cost reduction of the SRF cavities cold flanges is required. In this paper, a critical analysis of the TESLA-like cold connection flanges at room and at cryogenic temperature is presented. This analysis is based on experimental characterization of the mechanical properties of the joint and of the leak rates during the sealing process. A FEM model, that agrees with the experimental data, is also presented. This model is being used for the optimization of the present SRF flanges and the development of new cold connections.
MOPCH179	Design of a New Electropolishing System for SRF Cavities	DESY, KEK, controls, LANL	484
	T. Tajima LANL, Los Alamos, New Mexico C. Boffo Fermilab, Batavia, Illinois M.P. Kelly ANL, Argonne, Illinois J. Mammosser Jefferson Lab, Newport News, Virginia
	Electropolishing (EP) is considered the baseline surface treatment for Superconducting RF (SRF) cavities to achieve >35 MV/m accelerating gradient for the International Linear Collider (ILC). Based on the lessons learned at the forerunners such as KEK/Nomura, DESY and JLAB and on the recent studies, we have started a new design of the next EP system that will be installed in the US. This paper presents requirements, specifications, and the detail of the system design as well as the path forward towards the future industrialization.
MOPCH181	1.3 GHz Electrically-controlled Fast Ferroelectric Tuner	coupling, controls, feedback, klystron	487
	V.P. Yakovlev Omega-P, Inc., New Haven, Connecticut J.L. Hirshfield Yale University, Physics Department, New Haven, CT S. Kazakov KEK, Ibaraki
	A fast, electrically-controlled tuner is described with parameters suitable for operation with the 9-cell SC accelerator structure of ILC. The tuner is based on a magic tee and two phase shifters that contain ferroelectric rings. The dielectric constant of the ferroelectric ring is altered by applying a 4.2 kV DC pulse that provides an RF phase shift from 0 deg to 180 deg. This, in turn allows a change of the input signal amplitude from zero to its maximum value, or a change in phase from 0 deg to 360 deg during the RF pulse. It is shown that the possibility of changing the cavity coupling to the input line during the RF pulse allows significant RF power savings, up to 12.5 MW for the 800 GeV ILC option. In addition, fast electrically-tuned amplitude and phase control with a feed-back system should be useful to compensate for possible phase deviations of the input RF fields in each cavity of ILC to match the cavity with the feeding transmission line as the beam load varies.
MOPCH187	Key Cryogenics Challenges in the Development of the 4GLS	linac, cryogenics, FEL, ERLP	499
	R. Bate, R.K. Buckley, A.R. Goulden, C. Hodgkinson, S.M. Pattalwar CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	The fourth generation light source (4GLS) is a uniquely flexible source of ultra-high brightness continuous and pulsed radiation covering the IR to XUV range of the spectrum. It is the first light source in the world that is planned from the outset to be a multi-user, multi-source facility combining ERL (energy recovery LINAC) and FEL (free electron laser) technology. 4GLS will require six different sets of superconducting LINACs. Each of the LINAC modules consists of 2 to 7, 1.3 GHz superconducting RF cavities of the TESLA design operating at 1.8 K. The overall cooling power necessary to cool the cavities is estimated to be around 2.5KW demanding the superfluid liquid helium flow rates in excess of 200g/s. Even though the technology of the superconducting RF cavities is somewhat well understood, the design and subsequent operation of the cryogenic system / Cryo modules is an extremely complex task. In this paper we describe the key cryogenic challenges of the 4GLS project and our approach in identifying solutions to meet them.
MOPCH190	Cryomodule Development for Superconducting RF Test Facility (STF) at KEK	KEK, vacuum, superconducting-RF, alignment	505
	K. Tsuchiya, H. Hayano, Y. Higashi, H. Hisamatsu, M. Masuzawa, H. Matsumoto, C. Mitsuda, S. Noguchi, N. Ohuchi, T. Okamura, K. Saito, A. Terashima, N. Toge KEK, Ibaraki
	Current status of the cryomodule development for superconducting RF test facility, STF, at KEK is presented. The objective of the STF construction is to have an experience of 5-m long cryomodule fabrications and to learn an operational method of superconducting RF cavities. The STF consists of two 5-m long cryomodules, each housing four 9-cell cavities (one for 35 MV/m and the other for 45 MV/m). In addition to the cavity type, each cavity has variations in its appendices. Thus, two cryomodules must have different structures for the cavity support and for the port of the RF input coupler. This paper describes the details of the cryomodule design, the development of the bimetallic joint for connecting the titanium helium vessel to the stainless steel cooling pipe, and the studies of the magnetic shielding for high quality cavities.
MOPLS063	Accelerator Component Vibration Studies and Tools	quadrupole, resonance, DESY, vacuum	688
	R. Amirikas, A. Bertolini, W. Bialowons DESY, Hamburg
	This talk will cover a research program on accelerator component vibrations. Ground motion and technical noise, such as vacuum and refrigeration systems, couple to the beam, mainly via quadrupoles, making the design of their supports, especially, in the case of the superconducting magnets, critical. This program includes investigation of cold mass vibration of the superconducting quadrupoles inside an accelerating module and sensor performance in the main or fringe field of a linear collider detector. Seismometer accuracy limitations in correlated ground motion measurements are also being investigated.
MOPLS079	The Charged Beam Dumps for the International Linear Collider	linear-collider, collider, electron, photon	736
	R. Appleby UMAN, Manchester J.R.J. Bennett, T.A. Broome CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon C. Densham CCLRC/DL, Daresbury, Warrington, Cheshire H. Vincke CERN, Geneva
	The baseline configuration of the International Linear Collider requires 2 beam dumps per interaction region, each rated to 18MW of beam power, together with additional beam dumps for tuning purposes and machine protection. The baseline design uses high pressure moving water dumps, first developed for the SLC and used in the TESLA design, although a gas based dump is also being considered. In this paper we discuss the progress made by the international community on both physics and engineering studies for the beam dumps.
MOPLS084	Experimental Comparison at KEK of High Gradient Performance of Different Single Cell Superconducting Cavity Designs	KEK, DESY, controls, superconductivity	750
	F. Furuta, Y. Higashi, T. Higo, I.H. Inoue, S. Kazakov, Y. Kobayashi, H. Matsumoto, Y. Morozumi, R.S. Orr, T. Saeki, K. Saito, K. Ueno, H. Yamaoka KEK, Ibaraki J.S. Sekutowicz DESY, Hamburg
	We have performed a series of vertical tests of three different designs of single cell Niobium superconducting cavities at 2 degrees Kelvin. These tests aimed at establishing that an accelerating gradient of 45 MV/m could be reached in any of the designs, while using the standard KEK surface preparation. The designs tested were the Cornell re-entrant shape (RE), the DESY/KEK low loss shape (LL), and the KEK ICHIRO series. The cavities underwent surface preparation consisting of centrifugal barrel polishing, light chemical polishing, electropolishing, and finally a high pressure water rinse. All three kinds of cavities were used in a series of vertical tests to investigate details of the surface treatment. When using ultra-pure water for the high pressure rinse, the LL cavity reproducibly exceeded a gradient of 45 MV/m, the RE design reproducibly reached a gradient of between 50 MV/m and 52 MV/m, and three of the six ICHIRO cavities reached a gradient of between 45 MV/m and 49 MV/m.
MOPLS118	Magnetic Modelling of a Short-period Superconducting Helical Undulator for the ILC Positron Source	undulator, positron, photon, cryogenics	840
	J. Rochford, E. Baynham, T.W. Bradshaw, F.S. Carr CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon I.R. Bailey, L.I. Malysheva Cockcroft Institute, Warrington, Cheshire D.P. Barber DESY, Hamburg A.J. Brummitt, Y. Ivanyushenkov CCLRC/RAL, Chilton, Didcot, Oxon J.A. Clarke, O.B. Malyshev, D.J. Scott CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire P. Cooke, J.B. Dainton Liverpool University, Science Faculty, Liverpool G.A. Moortgat-Pick Durham University, Durham
	A positron source utilising undulators is now defined as the baseline option for the International Linear Collider (ILC). The ILC requires a short period undulator, as close to 10mm as possible, that is capable of producing 10 MeV photons. The HeliCal collaboration in the UK has undertaken a programme to design, develop and produce a prototype undulator. As part of the programme, the group has used the OPERA software package to perform the magnetic design of the undulator. The design has addressed several issues, including the effect of magnetic material for the undulator former, optimal winding geometry, the magnetic flux inside the superconductor and its variation with undulator period and the winding bore. This paper summarizes the results of both the 2d and the 3d magnetic simulations.
MOPLS133	Preliminary Studies of Ion Effects in ILC Damping Rings	ion, damping, electron, ion-effects	867
	G.X. Xia, Eckhard. Elsen DESY, Hamburg
	Ion effects are potentially detrimental to the performance of the damping rings for the International Linear Collider (ILC). In this paper, the ion effects in the damping rings of ILC are briefly reviewed. Fast beam-ion instability (FBII) is studied in the linear regime. The growth rates and the beam blowups due to FBII are analytically calculated and compared for two variants of the ILC damping ring designs (OCS and TESLA) and discussed as a function of the vacuum pressure. Finally, some detailed simulation results are also presented.
MOPLS142	Optimization of CESR-c Superferric Wiggler for the International Linear Collider Damping Rings	wiggler, damping, dynamic-aperture, lattice	894
	J.T. Urban, G. Dugan, M.A. Palmer Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
	We present the results of an optimization of the Cornell Electron Storage Ring (CESR) superferric wiggler for the International Linear Collider (ILC) damping ring. The superferric CESR wiggler has been shown to have excellent beam dynamics properties in the ILC damping ring. We reduced the physical size, and hence cost, of the CESR wiggler with minimal degradation of ILC damping ring beam dynamics. We will provide a description of the optimized superferric wiggler and show the performance of this wiggler in the ILC baseline damping ring.
TUPCH031	A New SQUID-based Measurement Tool for Characterization of Superconducting RF Cavities	cryogenics, pick-up, electron, shielding	1070
	K. Knaack, K. Wittenburg DESY, Hamburg R. Neubert, S. Nietzsche, W. Vodel FSU Jena, Jena A. Peters GSI, Darmstadt
	In this contribution a LTS-SQUID based measurement tool for characterization of superconducting RF cavities for the upcoming X-FEL project at DESY will be presented. The device makes use of the Cryogenic Current Comparator (CCC) principle and measures the so-called dark current, generated e.g. by superconducting cavities at high voltage gradients. To achieve the maximum possible energy the gradients should be pushed near to the physical limit of 50 MV/m. The measurement of the undesired field emission of electrons (the so-called dark current) in correlation with the gradient will give a proper value to characterize the performance of the RF cavities. The CCC mainly consists of a high performance LTS-DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the extracted dark current of the RF cavities. Therefore, a special designed toroidal niobium pick-up coil for the passing electron beam is superconducting connected across the input coil of the SQUID. The noise limited sensitivity of the CCC as well as new experimental results with the whole measurement device assembled in a special wide-necked LHe cryostat will be presented.
TUPLS106	Pulsed Bending Magnet of the J-PARC MR	power-supply, synchrotron, simulation, KEK	1747
	K. Koseki, H. Kobayashi, H. Nakayama, K.O. Okamura, M.J. Shirakata, M. Tawada KEK, Ibaraki
	Japan Proton Accelerator Research Complex (J-PARC) is under construction with a collaboration between Japan Atomic Energy Agency (JAEA) and High Energy Accelerator Research Organization (KEK). The J-PARC consists of a 180 MeV linac, a 3 GeV rapid-cycle synchrotron (RCS) and a 50 GeV synchrotron (MR). The bunch trains, which extracted from the RCS, is delivered both to the “Materials and Life Science Facility” and to the MR, two beam transport lines, 3-NBT and 3-50BT, are constructed. The switching of bunch trains is performed by a pulsed bending magnet. The field strength of 1.21 Tesla with rise and fall time of less than 40 msec is required. It was found that an effect induced by eddy current, which flows at thick end-plates, disturbs the flatness of the magnetic field. A simple compensation circuit has been adopted for a cure. A result from a field measurement, which shows a sufficient flatness, is presented.
WEXPA01	Latest Developments in Superconducting RF Structures for Beta=1 Particle Acceleration	XFEL, KEK, damping, higher-order-mode	1837
	P. Kneisel Jefferson Lab, Newport News, Virginia
	Superconducting RF technology is since nearly a decade routinely applied to different kinds of accelerating devices: linear accelerators, storage rings, synchrotron light sources and FEL's. With the technology recommendation for the International Linear Collider (ILC) a year ago, new emphasis has been placed on improving the performance of accelerating cavities both in Q-value and in accelerating gradients with the goal to achieve performance levels close to the fundamental limits given by the material parameters of the choice material, niobium. This paper will summarize the challenges to SRF technology and will review the latest developments in superconducting structure design. Additionally, it will give an overview of the newest results and will report on the developments in alternative materials and technologies.
	Transparencies
WEPLS043	Progress of the Rossendorf SRF Gun Project	gun, ELBE, cathode, vacuum	2469
	D. Janssen, A. Arnold, H. Buettig, R. Hempel, U. Lehnert, P. Michel, K. Moeller, P. Murcek, Ch. Schneider, R. Schurig, F. Staufenbiel, J. Teichert, R. Xiang FZR, Dresden T. Kamps, D. Lipka, F. Marhauser BESSY GmbH, Berlin W.-D. Lehmann IfE, Dresden J. Stephan IKST, Drsden V. Volkov BINP SB RAS, Novosibirsk I. Will MBI, Berlin
	In this paper we report the status and the progress of the superconducting RF gun project in Rossendorf. The gun is designed for cw operation mode with 1 mA current and 10 MeV electron energy. The cavity consists of three cells with TESLA geometry, a special designed half-cell in which the photo cathode will be inserted and a choke filter, which prevents the leakage of RF power by the coaxial line between the cathode and the cavity cell. A double tuner allows the tuning of the half-cell and the TESLA cells separately. In 2005 the fabrication of two cavities with RRR300 and RRR40 was finished. We present the results of the field measurement and the warm tuning of the cavity cells as well as the tuning and performance measurement of the choke filter. The fabrication of the double tuner has been also finished. In a test bench we measured the properties of the tuner (tuning range, resolution) at LN2 temperature. Further activities concern the diagnostic beam line of the gun, the new cathode preparation and cathode transfer system, the driver laser and the LHe transfer line.
WEPLS068	The IASA Magnetic Field Mapping (MFM) Project	electron, controls, resonance, dipole	2538
	E.P. Pournaras, A. Karabarbounis, C.N. Papanicolas, E. Stiliaris IASA, Athens
	The design and development of an automatic magnetic field mapping device as supporting equipment for the 10 MeV CW-Linac and its transport system at the Institute of Accelerating Systems and Applications (IASA) is presented. The MFM project aims to totally automate the operation of mapping room temperature magnetic field sources, reconstruct the 3D-field shape and reveal nonlinearities in the fridge field regions. The positioning system covers an area of 50x50 cm2 with an accuracy of less than 20 ?m in both axes; magnetic field measurements, mainly based on a Hall probe, can reach in precision the 1x 10-4 value. Several software tools for the visualization of the measured fields and for a direct comparison with theoretical estimates are also presented.
WEPLS108	High Field Solenoid Magnets for Muon Cooling	collider, emittance, luminosity, scattering	2634
	S.A. Kahn, M. Alsharo'a, P.M. Hanlet, R.P. Johnson, M. Kuchnir, D.J. Newsham Muons, Inc, Batavia R.C. Gupta, R. Palmer, E. Willen BNL, Upton, Long Island, New York
	Magnets made with high-temperature superconducting (HTS) coils operating at low temperatures have the potential to produce extremely high fields for use in beam lines and accelerators. The specific application of interest that we are proposing is to use a very high field (of the order of 50 Tesla) solenoid to provide a very small beta region for the final stages of cooling for a muon collider. With the commercial availability of HTS tape based on BSCCO technology with high current carrying capacity at 4.2 K, very high field solenoid magnets should be possible. In this paper we will evaluate the technical issues associated with building this magnet. In particular we will address how to mitigate the high Lorentz stresses associated with this high field magnet.
THPPA02	High-Gradient Superconducting Radiofrequency Cavities for Particle Acceleration	DESY, XFEL, radio-frequency, acceleration	2752
	L. Lilje DESY, Hamburg
	The development of radiofrequency superconductivity for particle acceleration has reached a level where many projects consider its use. One of the many attractive features of these accelerating structures is to achieve very high accelerating fields efficiently. The technology has been developped to a stage where accelerating gradients of more than 25 MV/m are being implemented in accelerator modules. In single-cell test resonators even higher gradients were already achieved. To operate cavities at these gradients efficiently their frequency needs to be kept stable to reduce the need for an overhead in radiofrequency power. Introducing active elements like piezoelectric actuators allows to achieve these goals.
	Transparencies
THXFI01	State of the Art in EM Field Computation	simulation, gun, dipole, SLAC	2763
	C.-K. Ng, V. Akcelik, A.E. Candel, S. Chen, N.T. Folwell, L. Ge, A. Guetz, H. Jiang, A.C. Kabel, K. Ko, L. Lee, Z. Li, E.E. Prudencio, G.L. Schussman, R. Uplenchwar, L. Xiao SLAC, Menlo Park, California
	This presentation will provide an up-to-date survey of the methods and tools for the computation of electromagnetic fields in accelerator systems and components.
	Transparencies
THPCH037	Wakefields Effects of New ILC Cavity Shapes	linac, emittance, simulation, DESY	2862
	I. Zagorodnov DESY, Hamburg N. Solyak Fermilab, Batavia, Illinois
	The operation of International Linear Collider (ILC) requires high gradients and quality factors in accelerating structure. One way to reach it is to modify the cavity shape to reduce the ratio of peak surface magnetic to accelerating field. Two candidate shapes are suggested recently: the Re-entrant shape and the Low-Loss shape. In this paper we estimate numerically longitudinal and transverse short range wake functions for the new shapes. The obtained analytical expressions are used in beam dynamic simulations for ILC lattice. We show that ILC will tolerate the cavities with the new shape and the smaller iris diameter.
THPCH040	Linac Focusing and Beam Break Up for 4GLS	focusing, linac, BBU, quadrupole	2871
	E. Wooldridge, B.D. Muratori CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	As part of the design for 4GLS the linac focusing and its effect on the beam break up (BBU) threshold have been studied. The choice of graded gradient focusing scheme is discussed and initial models of the focusing, using a triplet of quadrupoles between each of the modules within the linac, are presented. The quadrupoles were set-up in a defocusing - focusing - defocusing format with strengths of -1/2k, k, -1/2k. Using these models the BBU threshold was computed using available codes assuming a 9-cell TESLA cavity within the linac and a 7-cell design with HOM dampers. A sweep of the magnet strength with respect to the BBU threshold showed that there is an optimum setting.
THPCH041	Alternate Cavity Designs to Reduce BBU	BBU, recirculation, dipole, ERL	2874
	E. Wooldridge CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	An investigation was carried out on alternate cavity designs to decrease the effect of the higher order modes (HOMs) whilst maintaining the cavity accelerating gradient. The cavities were modelled in Microwave Studio and the number of cells per cavity and the number of cells per unit length were examined. HOM data from these models was used in beam break up (BBU) codes to calculate the threshold and the results are presented here. The cells of each cavity were slightly deformed alternately in the x and y planes so that the fundamental frequency of the cavity remained unperturbed, whilst minimising the HOM coupling between consecutive cells. Other patterns, such as alternating each deformed cell by several degrees, were also investigated. The data from these e-m models was also used in BBU calculations and their thresholds calculated.
THPLS024	Controlling the Vertical Emittance Coupling in CAMD	coupling, wiggler, quadrupole, resonance	3329
	V.P. Suller CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire M.G. Fedurin, P. Jines, D.J. Launey, T.A. Miller, Y. Wang LSU/CAMD, Baton Rouge, Louisiana
	The vertical beam size in the CAMD Light Source, as measured with an x-ray pinhole camera, indicates an emittance coupling ratio of 3%. This is consistent with the coupling ratio as measured by the betatron tune split when the coupling resonance is fully engaged. It has been shown that the coupling is mainly produced in the 7T wiggler, which is known to produce non-linear fields. To correct this coupling, it is proposed to install up to four skew quadrupoles. The results of testing a prototype skew quadrupole in the lattice are presented. It is shown that the coupling will be substantially corrected by suitably distributing and powering the four skew quadrupoles.
THPLS127	Plans for a 2nd Insertion Device in CAMD	wiggler, multipole, lattice, quadrupole	3583
	V.P. Suller CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire M.G. Fedurin, P. Jines, D.J. Launey, T.A. Miller, Y. Wang LSU/CAMD, Baton Rouge, Louisiana
	To allow the possible installation of a 2nd Insertion Device in the CAMD Light Source the lattice optic needs to be changed. The present configuration has a small vertical beta function in the long straight containing the 7T wiggler. The new optic will give small vertical beta at two long straights which are diametrically opposite. Test results with the new optic are presented together with the measured beam parameters. These are used to predict the photon beam performance for several types of Insertion Device which could be installed.