IPAC2014 - List of Keywords (coupling)

Paper	Title	Other Keywords	Page
MOZA01	Ultralow Emittance Beam Production based on Doppler Laser Cooling and Coupling Resonance	laser, ion, simulation, solenoid	28
	A. Noda, M. Nakao NIRS, Chiba-shi, Japan M. Grieser MPI-K, Heidelberg, Germany Z.Q. He FRIB, East Lansing, Michigan, USA Z.Q. He TUB, Beijing, People's Republic of China K. Jimbo Kyoto University, Kyoto, Japan H. Okamoto, K. Osaki HU/AdSM, Higashi-Hiroshima, Japan A.V. Smirnov JINR, Dubna, Moscow Region, Russia H. Souda Gunma University, Heavy-Ion Medical Research Center, Maebashi-Gunma, Japan H. Tongu Kyoto ICR, Uji, Kyoto, Japan Y. Yuri JAEA/TARRI, Gunma-ken, Japan
	Funding: Work supported by Advanced Compact Accelerator Development project by MEXT of Japan. It is also supported by GCOE project at Kyoto University, “The next generation of Physics-Spun from Universality" Doppler laser cooling has been applied to low-energy (40 keV) Mg ions together with the resonant coupling method* at the S-LSR at ICR, Kyoto University,. The S-LSR storage ring has a high super periodicity of 6, which is preferable from the beam dynamical point of view. At S-LSR one dimensional ordering of proton beam was already realized for the first time*. Active three dimensional laser cooling has been experimentally demonstrated for ions with un-negligible velocity (v/c=0.0019, where c is the light velocity) for the first time. Utilizing the above mentioned characteristics of S-LSR, an approach to realize ultralow emittances has been pursuit. To suppress heating effects, due to intra-beam scattering, the circulating ion beam intensity was reduced by scraping and beam emittances of 1.3·10^-11 pi m·rad and 8.5·10^-12 pi m·rad (normalized) have been realized for the horizontal and vertical directions, respectively with the 40 keV Mg ion beam at a beam intensity of ~10⁴, which is the lowest emittance ever attained by laser cooling. From MD computer simulations, it is predicted that reduction of the ion number to about 10³ is needed to realize a crystalline string. H. Okamoto, A.M. Sessler, D. Moehl, Phys. Rev. Lett. 72, 397 (1994). ** T. Shirai et. al., Phys. Rev. Lett. 98, 204801 (2007).
	Slides MOZA01 [13.336 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOZA01
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MOZA02	Advanced RF Design and Tuning Methods of RFQ for High Intensity Proton Linacs	rfq, linac, dipole, operation	34
	A. France CEA/IRFU, Gif-sur-Yvette, France
	The injector of high intensity linacs includes a Radio Frequency Quadrupole (RFQ) which must sustain high surface fields and thermal effects while accelerating intense low energy beams. For this purpose, the modelisation, realisation and tuning of accurate field laws is mandatory to preserve beam emittances and minimize beam losses. This presentation reviews the progress of advanced methods for the RF design, RF measurements during fabrication and final tuning of RFQ for high intensity linacs. It reports the ongoing developments on the injectors of high intensity demonstrators and of the linacs under construction such as SPIRAL2, LINAC4 or IFMIF-EVEDA.
	Slides MOZA02 [2.026 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOZA02
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MOPRO011	Employing Twin Crabbing Cavities to Address Variable Transverse Coupling of Beams in the MEIC*	electron, solenoid, proton, cavity	80
	A. Castilla DCI-UG, León, Mexico A. Castilla, J.R. Delayen, V.S. Morozov, T. Satogata JLab, Newport News, Virginia, USA A. Castilla, J.R. Delayen, V.S. Morozov, T. Satogata ODU, Norfolk, Virginia, USA
	Funding: *Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The design strategy of the Medium Energy Electron-Ion Collider (MEIC) at Jefferson Lab contemplates both matching of the emittance aspect ratios and a 50 mrad crossing angle along with crab crossing scheme for both electron and ion beams over the energy range (√s=20-70 GeV) to achieve high luminosities at the interaction points (IPs). However, the desired locations for placing the crabbing cavities may include regions where the transverse degrees of freedom of the beams are coupled with variable coupling strength that depends on the collider rings’ magnetic elements (solenoids and skew quadrupoles). In this work we explore the feasibility of employing twin rf dipoles that produce a variable direction crabbing kick to account for a range of transverse coupling of both beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO011
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MOPRO027	Measurements and Laboratory Tests on a Prototype Stripline Kicker for the CLIC Damping Rings	impedance, simulation, kicker, damping	125
	C. Belver-Aguilar, A. Faus-Golfe IFIC, Valencia, Spain M.J. Barnes, H.A. Day CERN, Geneva, Switzerland F. Toral CIEMAT, Madrid, Spain
	The Pre-Damping Rings (PDRs) and Damping Rings (DRs) of CLIC are required to reduce the beam emittances to the small values required for the main linacs. The injection and extraction, from the PDRs and DRs, are performed by kicker systems. To achieve both low beam coupling impedance and reasonable broadband impedance matching to the electrical circuit, striplines have been chosen for the kicker elements. Prototype striplines have been built: tests and measurements of these striplines have started. The goal of these tests is to characterize, without beam, the electromagnetic response of the striplines. The tests have been carried out at CERN. To study the signal transmission through the striplines, the measured S-parameters have been compared with simulations. In addition, measurements of longitudinal beam coupling impedance, using the coaxial wire method, are reported and compared with simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO027
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MOPRO032	Upgrades to the LHC Injection and Beam Dumping Systems for the HL-LHC Project	injection, kicker, dumping, impedance	141
	J.A. Uythoven, M.J. Barnes, B. Goddard, J. Hrivnak, A. Lechner, F.L. Maciariello, A. Mereghetti, A. Perillo Marcone, N.V. Shetty, G.E. Steele CERN, Geneva, Switzerland
	The HL-LHC project will push the performance of the LHC injection and beam dumping systems towards new limits. This paper describes the systems affected and presents the new beam parameters for these systems. It also describes the studies to be performed to determine which sub-components of these systems need to be upgraded to fulfill the new HL-LHC requirements. The results from the preliminary upgrade studies for the injection absorbers TDI are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO032
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MOPRO048	Update on Sirius, the New Brazilian Synchrotron Light Source	emittance, lattice, insertion, insertion-device	191
	L. Liu, A.P.B. Lima, N. Milas, A.H.C. Mukai, X.R. Resende, A.R.D. Rodrigues, F. H. de Sá LNLS, Campinas, Brazil
	Sirius is a 3 GeV synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). The electron storage ring uses the multi-bend-achromat approach (5BA in this case) to achieve a very low beam emittance of 0.28 nm.rad. The 518 m circumference contains 20 straight sections of alternating 6 and 7 meters in length, to be used for insertion devices as well as injection and RF systems. The 5BA cell is modified to accommodate a thin high field dipole (for 1.4˚ deflection) in the center of the middle bend producing hard X-ray radiation (12 keV critical energy) with a modest contribution to the total energy loss. This high field dipole (2.0 T) will be made of permanent magnet material, whereas the low field (0.58 T) ones, responsible for the main beam deflection, will be electromagnetic. Many challenges are associated with this kind of lattice, including both in beam dynamics and in accelerator engineering, that require R&D on new techniques. In this paper we discuss the main issues and achievements for Sirius during the last year.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO048
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MOPRO058	The Low-alpha Lattice and Bunch Length Limits at BESSY-VSR	radiation, storage-ring, optics, dipole	216
	P. Goslawski, M. Ries, M. Ruprecht, G. Wüstefeld HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung and Land Berlin. An upgrade of the BESSY II ring to a Variable bunch length Storage Ring BESSY^VSR has been recently proposed , by introducing strongly focusing superconducting cavities. This will allow to store simultaneously long and short bunches. In the regular user optics, bunch lengths of 15 ps (rms) and down to 1.5 ps (rms) are expected. Bunches as short as 300 fs (rms), close to the bunch length limit, and a ring current of 3.5 mA at the bunch bursting threshold can be provided by using a modified low-alpha optics. This presentation will discuss the properties of the low-alpha optics and intrinsic bunch length limits, given by coupling effects of the longitudinal and horizontal plane. G. Wüstefeld, A. Jankowiak, J. Knobloch, M.Ries, "Simultaneous Long and Short Electron Bunches in the BESSYII Storage Ring", Proceedings of IPAC2011, San Sebastian, Spain.
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MOPRO076	Elettra Status and Upgrades	operation, controls, dipole, emittance	261
	E. Karantzoulis, A. Carniel, S. Krecic Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with the latest studies and upgrades.
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MOPRO077	Betatron Coupling Numerical Study at Elettra	emittance, betatron, quadrupole, lattice	264
	S. Di Mitri, E. Karantzoulis Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	Elettra lacks skew quadrupoles and the coupling is controlled via the vertical orbit. Elettra has typical operational coupling of 1%, values as low as 0.3% were reached but however not easily established and reproducible. In order to control the coupling in a reproducible manner skew quadrupoles must be installed. Simulations of the betatron coupling and correction for the Elettra synchrotron light source were performed and are here presented. The numerical study is based on measured machine misalignments and carried out with the ELEGANT particle tracking code. The inclusion of families of skew quadrupoles in the existing lattice is investigated and shown to be conclusive for the coupling correction at the level of 0.1%.
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MOPME014	Automated Mode Recognition Algorithm for Accelerating Cavities	cavity, simulation, polarization, dipole	409
	K. Brackebusch, T. Galek, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: Work supported by Federal Ministry for Research and Education BMBF under contract 05K13HR1. Eigenmode simulations of accelerating structures often involve a large number of computed modes that need to be catalogued and compared. In order to effectively process all the information gathered from eigenmode simulations a new algorithm was developed to automatically recognize modes’ field patterns. In this paper we present the principles of the algorithm and investigate its applicability by means of different single and multi cell cavities. The highest achievable order of correctly recognized modes is of particular interest.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME014
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MOPME066	Development of 400 kA Pulsed Power Supply for Magnetic Horn at FAIR Antiproton Target	antiproton, radiation, operation, power-supply	517
	S.S. Mohite, R. Hettinger, K. Knie, I.J. Petzenhauser GSI, Darmstadt, Germany
	This report presents an overview of the magnetic horn and its pulsed power system at the upcoming FAIR (Facility for Antiproton and Ion Research) complex at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. In the planned antiproton (pbar) separator scheme a magnetic horn will be used as a device for collection and focusing of highly divergent antiprotons emerging from the target with energies around 3 GeV and within a cone of about 80 mrad .To achieve the desired focusing effect, the horn needs to be powered with a current pulse of 400 kA peak amplitude at the same repetition rate as the primary proton beam, i.e. 0.1 Hz. In future, operation up to 0.2 Hz is planned without major design alterations. Due to civil construction and radiation protection limitations, possible technical realization of this system has some key design issues. The aim is to develop a reliable and efficient magnetic horn system for effective focusing of antiprotons by producing a very strong pulsed magnetic field.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME066
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MOPME071	Configurations and Applications of Saturable Pulse Transformers in High Power Pulse Modulation	high-voltage, experiment, plasma, controls	532
	J. Liu, J. Gao, X.J. Ge, J. He, Y. Zhang NUDT, Changsha, People's Republic of China
	Saturable pulse transformers (SPTs) based on multiple batches of windings in parallel combination and coaxial cylindrical conductors are presented. The proposed SPT can be employed as the transformer and magnetic switch simultaneously for pulse capacitor or high-voltage pulse modulator of several hundred kV range. The SPT, with important features such as auto-resetting of core, high step-up ratio and low saturation inductance, achieves a compact integration of common transformer and magnetic switch. In the SPT, The physical suppression effect caused by reversed magnetic coupling mechanism among primary and secondary windings can reduce the saturation inductance of the SPT windings to a level lower than their structure inductances, which helps to achieve a magnetic switch with low saturation inductance. The proposed SPTs were applied in a high power pulse modulator based on a helical Blumlein pulse forming line (HBPFL). When the SPT played as a pulse transformer, the HBPFL can be charged to 200 kV. When the SPT played as a main magnetic switch of the HBPFL, it helped to form a quasi-square voltage pulse with amplitude of 180 kV，pulse duration of 130 ns, rise time of 60 ns.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME071
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MOPME081	A Stripline Kicker Driver for the Next Generation Light Source	kicker, high-voltage, simulation, impedance	559
	F.M. Niell, N. Butler, M.P.J. Gaudreau, M.K. Kempkes, J. Kinross-Wright Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Funding: US Department of Energy, Award DE-SC00004255 Diversified Technologies, Inc. (DTI) assembled a prototype pulse generator capable of meeting the original specifications for the Next Generation Light Source (NGLS) fast deflector. The ultimate NGLS kicker driver must drive a 50 Ω terminated Transverse Electromagnetic (TEM) deflector blade at 10 kV, with flat-topped pulses and a sustained repetition rate of 100 kHz. Additional requirements of the specification include a 2 ns rise time (10 – 90%), a highly repeatable flattop with pulse width from 5 – 40 ns, and a fall time less than 1 μs (down to 10-4 of the peak value). The driver must also effectively absorb high-order mode signals emerging from the deflector itself. It is envisioned that a scintilla of deflection will be imparted by a symmetric pair of shaped parallel deflection blades, pulsed in opposition at 10 kV. Within the guide, each TEM wave produced by the two pulse generators traverses the guide synchronously with the selected (relativistic) charge packet. The DTI team has designed and demonstrated the key elements of a solid state kicker driver capable of meeting the NGLS requirements, with possible extension to a wide range of fast-pulse applications.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME081
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MOPRI008	A Compact 2.45 GHz Microwave IOn Source Based High Fluence Irradiation Facility at IUAC, Delhi	ion, plasma, ion-source, extraction	592
	N. Kumar, R. Ahuja, R.N. Dutt, D. Kanjilal, P.S. Lakshmy, Y. Mathur, G.O. Rodrigues IUAC, New Delhi, India
	A compact 2.45 GHz microwave ion source based low energy ion been facility has been developed for performing various experiments in material science and for studies related to plasma physics. The design of the compact microwave source is based on a tunable permanent magnet configuration and is powered by a 2 kW magnetron [1,2]. The double walled, water cooled stainless steel plasma chamber and ridge waveguide have been fabricated using the latest ‘LaserCUSING’ technique. The electron energy distribution functions have been measured in a similar low frequency ion source and validated by model calculations [1]. Extraction of the beam can also be performed at very low voltages in the order of hundreds of volts with high intensities by nullifying the space charge effects with the secondary electrons. The facility will be used for ion implantation, phase formation, surface etching and pattering experiments. The design aspects of the microwave ion source and low energy beam transport system will be presented. * “Studies on the effect of the axial magnetic field on the x-ray bremsstrahlung in a 2.45 GHz permanent magnet microwave ion source” Narender Kumar et. al. accepted for publication in RSI.
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MOPRI033	Quasi-traveling Wave Side Couple RF Gun Commissioning for SuperKEKB	gun, cavity, emittance, cathode	667
	T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou KEK, Ibaraki, Japan
	We are developing a new RF gun for SuperKEKB. High-charge low-emittance electron and positron beams are required for SuperKEKB. We will generate 7.0 GeV electron beam at 5 nC 20 mm-mrad by J-linac. In this linac, a photo cathode S-band RF gun will be used as the electron beam source. For this reason, we are developing an advanced RF gun. New RF gun which has two side coupled standing wave field is developed. We call it quasi traveling wave side couple RF gun. This gun has a strong focusing field at the cathode and the acceleration field distribution also has a focusing effect. Beam commissioning has been started with the new RF gun. I will report the result of beam commissioning.
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MOPRI043	Study of a C-band Standing-wave Gun for the SwissFEL Injector	gun, cathode, solenoid, emittance	698
	M. Schaer, S. Bettoni, A. Citterio, P. Craievich, M. Negrazus, L. Stingelin, R. Zennaro PSI, Villigen PSI, Switzerland
	The baseline design of the SwissFEL injector foresees the "PSI Gun 1", a 2.6-cell RF photo-cathode gun operating at S-band frequency, as the electron source. In this paper a new design is presented where a 5.6-cell C-band gun could replace the PSI Gun 1 with no impact on the rest of the injector setup. A conservative maximum gradient of 135 MV/m at the cathode is assumed which drives the electron beam faster into the relativistic regime and therefore allows to tolerate larger charge densities. The presented solution also foresees a coaxial RF coupling from the cathode side in order to place the gun solenoid as near to the photo-cathode as possible, improving the emittance compensation. Astra simulations showed that the transverse beam brightness can be doubled before the first bunch compressor preserving the low transverse emittance value as compared to the current design for the S-band injector configuration of SwissFEL.
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TUOAB01	Computation of Eigenmodes in Long and Complex Accelerating Structures by Means of Concatenation Strategies	cavity, factory, HOM, FEL	947
	T. Flisgen, J. Heller, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: This research was partially funded by the EuCARD project which is co-funded by European Commission 7th in Framework Programme (FP7). The computation of eigenmodes for complex accelerating structures is a challenging and important task for the design and operation of particle accelerators. Discretizing long and complex structures to determine its eigenmodes leads to demanding computations typically performed on super computers. This contribution presents an application example of a method to compute eigenmodes and other parameters derived from these eigenmodes for long and complex structures using standard workstation computers. This is accomplished by the decomposition of the complex structure into several single segments. In a next step, the electromagnetic properties of the segments are described in terms of a compact state space model. Subsequently, the state space models of the single structures are concatenated to the full structure. The results of direct calculations are compared with results obtained by the concatenation scheme in terms of computational time and accuracy.
	Slides TUOAB01 [1.781 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUOAB01
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TUPRO018	Prospects for the LHC Optics Measurements and Corrections at Higher Energy	optics, software, GUI, quadrupole	1046
	R. Tomás, T. Bach, J.M. Coello de Portugal, V. Kain, M. Kuhn, A. Langner, Y.I. Levinsen, K.S.B. Li, E.H. Maclean, N. Magnin, V. Maier, M. McAteer, T. Persson, P.K. Skowroński, R. Westenberger CERN, Geneva, Switzerland E.H. Maclean JAI, Oxford, United Kingdom S.M. White BNL, Upton, Long Island, New York, USA
	LHC will resume operation in 2015 at 6.5 TeV. The higher energy allows for smaller IP beta functions, further enhancing the optics errors in the triplet quadrupoles. Moreover the uncertainty in the calibration of some quadrupoles will slightly increase due to saturation effects. The complete magnetic cycle of the LHC will take longer due to the higher energy and extended squeeze sequence. All these issues require more precise and more efficient optics measurements and corrections to guarantee the same optics quality level as in 2012 when a 7% peak beta-beating was achieved. This paper summarizes the on-going efforts for achieving faster and more accurate optics measurements and corrections.
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TUPRO035	Vertical Emittance at the Quantum Limit	emittance, quadrupole, storage-ring, sextupole	1096
	R.T. Dowd, Y.E. Tan SLSA, Clayton, Australia K.P. Wootton The University of Melbourne, Melbourne, Victoria, Australia
	Further reduction of betatron coupling and vertical dispersion in the storage ring of the Australian Synchrotron Light Source has resulted in the achievement of a beam vertical emittance that is now dominated by the intrinsic quantum effects. This paper will detail the key elements in achieving a vertical emittance at the quantum limit and results achieved.
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TUPRO050	Measurements of the Optical Functions at FLASH	optics, quadrupole, linac, controls	1141
	J. Zemella, T. Hellert, M. Scholz, M. Vogt DESY, Hamburg, Germany
	In 2013 the superconducting soft x-ray Free Electron Laser FLASH at DESY (Hamburg, Germany) the extraction section needed to connect the 2nd beam line FLASH2 was installed. In order to allow simultaneous operation of the two beam lines (FLASH1/2), the optical functions in the extraction area needed to be modified. During the recommissioning of FLASH we have optimized, measured and corrected the optical functions in the machine. We report on the the results and the methods.
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TUPRO052	Study a ‘Sum’ Linear Coupling Resonance for J-PARC Main Ring: Observations and Simulations	resonance, operation, injection, emittance	1147
	A.Y. Molodozhentsev, S. Igarashi KEK, Ibaraki, Japan Y. Sato, J. Takano J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	J-PARC Main Ring should deliver a high-power proton beam to neutrino experiments with limited particle losses. To meet this requirement low-order machine resonances have to be compensated. The linear coupling resonance Qx+Qy=43 has been identified as the potential source for significant particle losses at the collimator. The resonance compensation scheme has been studied experimentally by using a low intensity beam. To understand this process the simulations have been performed by using the PTC-ORBIT code. The Main Ring model has been developed to reproduce the machine operation including the initial stage of the acceleration. The 6D beam model has been defined to represent the ‘pencil’ beam used for this study. In frame of this report the single and multi particle dynamics will be discussed to understand the results of measurements, performed during RUN44 (November 2012). The results of the long-term tracking for this case will be presented. The obtained results can be used to benchmark the computer modeling the ‘sum’ linear coupling resonance with the experimental results.
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TUPRO057	Solenoid Siberian Snake Without Compensation of Betatron Oscillation Coupling in Nuclotron@JINR	solenoid, betatron, lattice, focusing	1162
	Y. Filatov, V.A. Mikhaylov JINR, Dubna, Russia A.V. Butenko, A.D. Kovalenko JINR/VBLHEP, Moscow, Russia Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	The influence of solenoids on spin is very efficient, but beam focusing is determined mainly by structural quadru-poles. The condition of stable orbital motion of particles does not require compensation of the betatron oscillation coupling. To reduce the influence of the Snake on orbital motion it is desirable to exclude compensating quads completely. The design of solenoid Siberian snake for the Nuclotron lattice is presented. The orbital functions of the lattice were calculated and the results are discussed.
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TUPRO075	Initial Analysis of the 4D Transfer Map in the Emma Non-Scaling Fixed Field Alternating Gradient Accelerator	simulation, betatron, quadrupole, alignment	1214
	C.S. Edmonds, A. Wolski The University of Liverpool, Liverpool, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom B.D. Muratori, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: STFC The EMMA non-scaling Fixed Field Alternating Gradient accelerator (ns FFAG) is a ring consisting of 42 quadrupole pairs. The dipole fields which guide particles around the ring are arrived at through offsetting the quadrupoles from a reference axis. In the ideal case, first order 4D transfer maps will describe the turn by turn progression of a particle bunch in transverse phase space. This contribution sees the use of experimental data to calculate the 4D transfer map for EMMA at several different momenta, and a comparison made with maps produced through simulation.
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TUPME011	The Status of the Construction of MICE Step IV	solenoid, experiment, emittance, cavity	1364
	P. Snopok IIT, Chicago, Illinois, USA E. Overton Sheffield University, Sheffield, United Kingdom
	Funding: DOE, NSF, STFC, INFN, CHIPP and several others The International Muon Ionization Cooling Experiment will provide the demonstration ionization cooling. The experiment is being built in a series of Steps. Step IV, which consists of a tracking spectrometer upstream and downstream of an absorber/focus-coil (AFC) module will be completed in early in 2015. In this configuration, the emittance of the muon beam upstream and downstream of the absorber will be measured precisely allowing the emittance reduction and the factors that determine the ionization cooling effect to be studied in detail. The AFC module is a 22 liter volume of liquid hydrogen placed inside a superconducting focusing coil. The properties of lithium hydride, and possibly other absorber materials, will also be studied. All the components of Step IV have been manufactured and integration of the experiment in the MICE Hall at the Rutherford Appleton Laboratory is underway. A full study of ionization cooling will be carried out with Step V, which will include a short 201 MHz linac module in which beam transport is achieved with a superconducting “coupling coil”. The status of the preparation of the components of Step V of the experiment will be described briefly.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME011
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TUPME025	Progress on Low Emittance Tuning for the CLIC Damping Rings	quadrupole, emittance, sextupole, dipole	1404
	J. Alabau-Gonzalvo, H. Bartosik, Y. Papaphilippou CERN, Geneva, Switzerland
	In the frame of the CLIC main Damping Ring a study on the sensitivity of the lattice to different sources of misalignment is presented. The minimum equilibrium emittance is simulated and analytically estimated under dipole and quadrupole rolls, and quadrupole and sextupole vertical offsets. The result of this study establishes alignment tolerances to preserve the vertical emittance below the design value (1 pm·rad). Non-linear dynamics studies have been done to determine the dynamic aperture in the presence of misalignments.
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TUPME038	Wakefield excitation via a metasurface-loaded waveguide	impedance, wakefield, simulation, radiation	1437
	E. Sharples Cockcroft Institute, Lancaster University, Lancaster, United Kingdom R. Letizia Lancaster University, Lancaster, United Kingdom
	Funding: Work supported by STFC Quota Studentship grant ST/K520133/1 A metallic waveguide loaded with layers of complementary split ring resonator (CSRR) based metasurface is presented for accelerator and coherent source applications. This structure presents left handed behaviour arising from the strong electrical response of CSRRs which form the metasurface and the transverse field confined between the closely positioned metasurface layers. The loaded waveguide structure is known to have a TM-like mode at 5.47GHz suitable for acceleration. In this paper, the results of wakefield simulations are presented and a narrow band excitation identified around the frequency of the TM-like mode, indicating strong coupling between the beam and the field of this mode.
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TUPME053	Study of the Energy Modulated Electron Cyclotron Resonance Ion Source for the Coupled RFQ-SFRFQ Cavity	ion, ion-source, cavity, ECR	1486
	W.L. Xia, J.E. Chen, S.L. Gao, Z.Y. Guo, Y.R. Lu, S.X. Peng, Z. Wang, X.Q. Yan, J. Zhao, K. Zhu PKU, Beijing, People's Republic of China
	The coupled RFQ and SFRFQ cavity has been manufactured and tested recently. According to the beam dynamic design, the input He⁺ beam within 120° phase width is designed for the cavity to achieve over 98% transmission efficiency. An energy modulated electron cyclotron resonance (ECR) ion source was proposed and simulated. To achieve the 1% energy modulation on the 30keV direct current (DC) beam, two simplified RF power feeding structures for beam bunching were studied. The simulations show positive results as well as the bunched beam is achieved by the energy modulated ECR ion source.
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TUPRI025	Interplay of Touschek Scattering, Intrabeam Scattering, and RF Cavities in Ultralow-emittance Storage Rings	emittance, lattice, storage-ring, scattering	1612
	S.C. Leemann MAX-lab, Lund, Sweden
	When it goes into operation in 2016, the MAX IV 3 GeV storage ring will be the first ultralow-emittance storage ring based on a multibend achromat lattice. These lattices make use of a large number of weak bending magnets which considerably reduces the amount of power radiated in the dipoles in comparison to power radiated from insertion devices. Therefore parameters such as emittance, energy spread, and radiated power are no longer constant during a typical user shift. Since the charge per bunch is usually high, intrabeam scattering (IBS) becomes very strong creating a dependence of emittance on stored current. Since the bunch length can vary as insertion device gaps change, the emittance blow-up from IBS is not constant either. Therefore, the emittance, bunch length, and hence the resulting Touschek lifetime have to be calculated in a self-consistent fashion taking into account the bare lattice, RF cavity settings, bunch charge, and gap settings. This paper demonstrates the intricate interplay between transverse emittance (insertion devices, emittance coupling), longitudinal emittance (tuning of main cavities as well as harmonic Landau cavities), and choice of stored current.
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TUPRI030	Beam Coupling Impedance of the New Beam Screen of the LHC Injection Kicker Magnets	impedance, kicker, injection, operation	1627
	H.A. Day, M.J. Barnes, F. Caspers, E. Métral, B. Salvant, J.A. Uythoven CERN, Geneva, Switzerland
	The LHC injection kicker magnets experienced significant beam induced heating of the ferrite yoke, with high intensity beam circulating for many hours, during operation of the LHC in 2011 and 2012. The causes of this beam coupling impedance were studied in depth and an improved beam screen implemented to reduce the impedance. Results of measurements and simulations of the new beam screen design are presented in this paper: these are used to predict power loss and temperature of the ferrite yoke for operation after long shutdown 1 and for proposed HL-LHC operational parameters.
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TUPRI045	Beam Coupling Impedance Simulation in the Frequency Domain for the SIS100 Synchrotron	impedance, space-charge, dipole, synchrotron	1665
	U. Niedermayer, O. Boine-Frankenheim TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim GSI, Darmstadt, Germany
	For the quantification of intensity thresholds due to coherent instabilities and beam induced heating in the FAIR synchrotron SIS100 a detailed knowledge of transverse and longitudinal beam coupling impedance is required. Due to the rather long proton and heavy-ion bunches, the relevant spectrum is below 100MHz. For the computation of beam coupling impedances in the low frequency regime, frequency domain methods are more advantageous than (explicit) time domain methods. We show the setup of a 2D finite element code that allows to compute the impedance for arbitrary longituninally homogeneous beam and structure shapes. Perfectly conducting pipes, a dispersive ferrite tube, and thin resistive beam pipe serve as test cases. The influence of the beam velocity on the coupling impedance is studied.
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TUPRI047	Electromagnetic Modeling of Open Cell Conductive Foams for High Synchrotron Radiation Rings	impedance, synchrotron, synchrotron-radiation, radiation	1671
	S. Petracca, A. Stabile U. Sannio, Benevento, Italy A. Stabile INFN-Salerno, Baronissi, Salerno, Italy
	Open cell conductive foams (OCMF) have been recently suggested as an alternative to perforated metal patches for efficiently handling gas desorption from the beam pipe wall due to intense synchrotron radiation, yielding superior performance in terms of residual gas concentration and beam shielding. Experimental work is ongoing to assess their properties, including secondary emission yields and beam coupling impedances. In this communication we attempt a review of the Literature about electromagnetic modeling of OCMF, and outline a general framework for computing the surface impedance of OCMF walls and deriving the longitudinal and transverse beam coupling impedances thereof, based on effective medium theory and electromagnetic reciprocity. A critical analysis of the relevant modeling approximations is included.
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TUPRI054	FEM Analysis of Beam-coupling Impedance and RF Contacts Criticality on the LHC UA9 Piezo Goniometer	impedance, simulation, resonance, experiment	1692
	A. Danisi, R. Losito, A. Masi, A. Passarelli, B. Salvant, C. Zannini CERN, Geneva, Switzerland
	The UA9 piezo-goniometer has been designed to guarantee micro-radians-accuracy angular positioning of a silicon crystal for a crystal collimation experiment in the LHC, and to minimize the impact on the LHC beam-coupling impedance. This paper presents a Finite Element Method (FEM) study of the device, in both parking and operational positions, to evaluate its impact on the LHC impedance budget. The study has been a progressive simulation work, started from the simplification of the original detailed design, and aimed at highlighting the effect of single details (e.g. objects in confining chambers) on the longitudinal and transverse components of beam-coupling impedance. In addition, the shielding contribution of the RF gaskets has been carefully evaluated, with the objective to assess the consequences for operation in case of their failure. Sensitivity analyses to simulation parameters are also performed, in order to test the FEM model robustness. A final word is drawn on the overall device impedance criticality.
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TUPRI055	Theoretical Analysis of Metamaterial Insertions for Resistive-wall Beam-coupling Impedance Reduction	impedance, insertion, vacuum, interface	1695
	A. Danisi, R. Losito, A. Masi, B. Salvant, C. Zannini CERN, Geneva, Switzerland
	Resistive-wall impedance usually constitutes a significant percentage of the total beam-coupling impedance budget of many accelerator structures (e.g. for LHC, it can be more than 50%). Reduction techniques for resistive-wall components entail high electrical-conductivity coatings. This paper proposes the use of metamaterials, having negative values of magnetic permeability or dielectric permittivity (or both), for sensibly reducing or theoretically nearly cancelling the resistive-wall component of beam-coupling impedance. The proposed approach is developed by means of an equivalent transmission-line model, whose results show the potential reduction of both longitudinal and transverse impedance when using metamaterial insertions. The effects on the real and imaginary part have been singled out. The effectiveness of such materials is discussed both for negative-permittivity and for negative-permeability cases, which actually show different impacts and can be then target of proper engineering. This first-stage study opens the possibility of considering metamaterials for impedance mitigation or for setting up proper experimental setups.
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TUPRI061	Power Loss Calculation in Separated and Common Beam Chambers of the LHC	impedance, electron, simulation, cryogenics	1711
	C. Zannini, G. Iadarola, G. Rumolo CERN, Geneva, Switzerland G. Iadarola Naples University Federico II, Science and Technology Pole, Napoli, Italy
	The performance of 25 ns beams in the LHC is strongly limited by the electron cloud. To determine the amount electron cloud in the cold sections of the machine, it is very important to be able to disentangle the beam induced heating due to the beam coupling impedance from that attributable to electron cloud. This paper will focus on the calculation of the first contribution. First, the impedance model used for the calculation of the beam induced power loss is briefly discussed. Then, the methods for the calculation of the beam induced power loss in regions with one or two beams are also described. Finally, the calculated power loss is compared with the measured heat loads for both 25 and 50 ns beams in both the LHC arcs and in the inner triplets (ITs).
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TUPRI062	The Mode Matching Technique Applied to the Transverse Beam Coupling Impedance Calculation of Azimuthally Symmetric Devices of Finite Length	impedance, cavity, simulation, vacuum	1714
	N. Biancacci, E. Métral, B. Salvant, C. Zannini CERN, Geneva, Switzerland M. Migliorati, L. Palumbo URLS, Rome, Italy V.G. Vaccaro Naples University Federico II and INFN, Napoli, Italy
	The infinite length approximation is often used to simplify the calculation of the beam coupling impedance of accelerator elements. This is expected to be a reasonable assumption for devices whose length is greater than the transverse dimension but may be a less accurate approximation for segmented devices. In this contribution we present the extension of the study of the beam coupling impedance of a finite length device to the transverse plane. In order to take into account the finite length, we decompose the fields in the cavity and in the beam pipe into a set of orthonormal modes and apply the Mode Matching method to obtain the impedance. To validate our method, we will present comparisons between analytical formulas and 3D electromagnetic CST simulations.
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TUPRI063	Electromagnetic Simulations for Non-ultrarelativistic Beams and Application to the CERN Low Energy Machines	impedance, simulation, space-charge, vacuum	1718
	C. Zannini, N. Biancacci, T.L. Rijoff, G. Rumolo CERN, Geneva, Switzerland T.L. Rijoff TU Darmstadt, Darmstadt, Germany
	In the framework of the PS-Booster upgrade project an accurate impedance model is needed in order to determine the effect on the beam stability and assess the impact of the new devices to be installed in the machine. CST 3-D EM simulations are widely used to estimate the impedance contribution of the different devices along the CERN accelerator complex. Unlike the highly relativistic case, in which the reliability of the EM solver has been proved in many specific cases by comparing simulations with analytical results, the nonrelativistic case has been so far not yet benchmarked. In order to use systematically CST 3-D EM simulations for the PS-Booster, or even lower energy machines like the antiproton decelerator ELENA, a validation campaign has been carried out. The main complication to single out the beam coupling impedance, as resulting from the interaction of the beam with the surroundings, consisted of removing reliably the strong contribution of the direct space charge of the source bunch, which is included in the EM calculation. The simulation results were then benchmarked with the analytical results for the case of a PEC cylindrical tube and of a ferrite loaded kicker.
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TUPRI087	A Wideband Slotted Kicker Design for SPS Transverse Intra-bunch Feedback	kicker, impedance, feedback, interface	1772
	J.M. Cesaratto, J.D. Fox, C.H. Rivetta SLAC, Menlo Park, California, USA D. Alesini, A. Gallo, M. Zobov INFN/LNF, Frascati (Roma), Italy S. De Santis LBNL, Berkeley, California, USA W. Höfle CERN, Geneva, Switzerland
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP) and by the EU FP7 HiLumi LHC - Grant Agreement 284404. In order for the SPS to meet the beam intensity demands for the HL-LHC upgrade, control and mitigation of transverse beam instabilities caused by electron cloud and TMCI will be essential. For this purpose a wideband intra-bunch feedback method has been proposed, based on a 4 GS/s front end data acquisition and processing, and on a back end frequency response extending to at least 1 GHz. A slotted type kicker, similar to those used for stochastic cooling, as well as an array of stripline kickers have been considered as the terminal elements of the feedback system. A slotted TEM type kicker has been designed fulfilling the bandwidth and kick strength requirements for the SPS application. In this paper we present an updated version of the design and electromagnetic characteristics, leading into the mechanical design and construction of the kicker occurring later this year.
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TUPRI104	A Beam Arrival Time Cavity for REGAE at DESY	cavity, electron, gun, operation	1820
	M. Hansli, A. Angelovski, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany K. Flöttmann, D. Lipka, H. Schlarb, S. Vilcins DESY, Hamburg, Germany F.J. Grüner, B. Zeitler CFEL, Hamburg, Germany
	Funding: Kindly funded by BMBF within FSP302. REGAE (Relativistic Electron Gun for Atomic Exploration) at DESY in Hamburg is a linear accelerator for electron diffraction experiments. It is upgraded to allow for laser driven wake field accelerator experiments. The bunch length is around 10 fs and the wakefield structure is about 100 fs and the synchronization of the laser and the electron bunch needs to be in order of the bunch length. To achieve this, a RFbased scheme will be used, comparing the phase of a beam induced signal with the reference clock. To improve the performance for the operation with charges well below 1 pC a beam arrival time cavity (BAC) at 3.025 GHz is foreseen as a highly sensitive pickup. To provide the maximum energy to the measurement electronics, the cavity needs a high R=Qvalue and an optimized coupling. An over-coupled setting might be beneficial as it provides a higher signal-to-noise ratio for the first samples. In this paper the concept of the beam arrival time cavity, the influence of the dark current on the measurement and parameter studies and optimization of the cavity itself are presented.
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WEOCA03	DAΦNE Operation with the Upgraded KLOE-2 Detector	luminosity, detector, operation, collider	1883
	C. Milardi, D. Alesini, M.E. Biagini, M. Boscolo, B. Buonomo, S. Cantarella, A. De Santis, G.O. Delle Monache, G. Di Pirro, A. Drago, L.G. Foggetta, O. Frasciello, A. Gallo, A. Ghigo, F. Guatieri, S. Guiducci, F. Iungo, C. Ligi, G. Mazzitelli, L. Pellegrino, R. Ricci, U. Rotundo, C. Sanelli, G. Sensolini, M. Serio, A. Stecchi, A. Stella, M. Zobov INFN/LNF, Frascati (Roma), Italy R. Gargana, A. Michelotti Consorzio Laboratorio Nicola Cabibbo, Frascati, Italy D.N. Shatilov BINP SB RAS, Novosibirsk, Russia M. Tobiyama KEK, Ibaraki, Japan A. Valishev Fermilab, Batavia, Illinois, USA
	The DAΦNE collider has been successfully commissioned after the experimental detector modification and a major upgrade and consolidation program involving a large part of the accelerator complex. This paper presents the Φ-Factory setup and the achieved performances in terms of beam currents, luminosity, detector background and related aspects.
	Slides WEOCA03 [2.424 MB]
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WEPRO016	Injection/Extraction Kicker for the ALS-U Project	kicker, impedance, injection, extraction	1977
	S. De Santis, W. Barry, S. Kwiatkowski, T.H. Luo, G.C. Pappas, L.R. Reginato, D. Robin, C. Steier, C. Sun, H. Tarawneh, W.L. Waldron LBNL, Berkeley, California, USA
	Funding: Work supported by the US Department of Energy under Contract no. DEAC02-05CH11231 The ALS-II proposal consists in the upgrade of the existing Advanced Light Source at LBNL to a new ultra-low emittance lattice for production of diffraction-limited soft x-rays. In order to compensate for the reduced beam lifetime we intend to operate the machine in continuous top-off mode, where one of several bunch trains is extracted every 30-60 seconds and swapped with a fresh train from the accumulator ring, which is injected on axis without perturbing the circulating beam. In this paper we present a possible design for the injection/extraction kicker based on matched stripline electrodes. The main parameters of such a kicker are discussed in reference to the minimum gap between trains, the storage ring lattice, and the characteristics of a suitable pulser. We also present results from 3D electromagnetic modeling of the proposed kicker performed to evaluate its rise and fall time and field uniformity characteristics.
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WEPRO066	Study for Space Charge effect in tune space at J-PARC MR	resonance, space-charge, quadrupole, simulation	2100
	K. Ohmi, S. Igarashi KEK, Ibaraki, Japan H. Harada JAEA, Ibaraki-ken, Japan Y. Sato J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Choice of tune operating point is serious for operation of high intensity proton machine. Space charge force induces tune spread and nonlinear resonance. Nonlinear resonances are also contained in accelerator lattice. We discuss optimization of operating point based on space charge simulation in J-PARC Main Ring.
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WEPRO097	The Base Parameters of the Compact 27 GHz Electron Linac for Medical Application	electron, linac, simulation, injection	2189
	S.M. Polozov, T.V. Bondarenko, Yu.D. Kliuchevskaia, V.I. Rashchikov MEPhI, Moscow, Russia
	A compact and light-weight electron linac is attractive for a number of medical applications including intra-operational and cyber-knife systems. The design of such an accelerator can nowadays be based on using of a powerful high-voltage high-frequency gyrotron which can provide now in pulsed regime a peak power up to 15 MW at the frequency about of 30 GHz. Taking into account this possibility, the paper presents the results of design and numerical simulations for the electron beam dynamics in a linac with the operating frequency of 27 GHz. Designed linac consists of two parts: gentle buncher and main accelerating section. The beam bunching is complicated at 1 cm wavelength because high energy about 2 MeV is necessary for beam injection into the main stage with v/c=1. Beam dynamics simulations are held using BEAMDULAC-BL code. The electrodynamics of accelerating structure based on biperiodic structure is presented. The electron gun simulation is also discussed. The RF feeding is planned to be realized using a gyrotron to be designed in IAP RAS. The gyrotron is capable to produce 2 MW peak RF power in pulses with pulse duration 400 μs and repetition rate 10 Hz. T.V. Bondarenko, E.S. Masunov, S.M. Polozov. BEAMDULAC-BL code for 3D simulation of electron beam dynamics taking into account beam loading and coulomb field. PAST, 2014 (in press).*
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WEPRO110	Power Plant Based on Subcritical Reactor and Proton LINAC	neutron, target, proton, booster	2224
	A.G. Golovkina, I.V. Kudinovich, D.A. Ovsyannikov St. Petersburg State University, St. Petersburg, Russia A.A. Bogdanov KSRC, St. Petersburg, Russia
	Nuclear power plant based on accelerator driven subcritical reactor (ADSR) is considered. Such systems demonstrate higher safety because the fission proceeds in subcritical core and necessary neutron flux is reached with external neutrons generated in target of heavy nuclides. In order to efficiently use ADSR for energy production, it’s needed the total power, generated in the reactor, to be greater than power inputs for charged particles acceleration. The plant driven by middle-energy accelerator, which is cheaper than high-energy accelerators, proposed for these purposes, is considered. So it’s necessary to find other ways to amplify reactor power outputs. Thus, the technical solution to increase power gain of small-sized power plant with a linear proton accelerator (energy 300-400 MeV, average current 5 mA) is proposed. Thermal power up to 300 MW was reached.
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WEPME007	Multi-Bunch Generator Cavity	cavity, impedance, electron, cathode	2267
	E.A. Savin, S.V. Matsievskiy, Ya.V. Shashkov, N.P. Sobenin MEPhI, Moscow, Russia A.A. Zavadtsev Nano, Moscow, Russia
	The concept of the six bunch generator cell for the washers and diaphragm loaded structure (Moscow Meson Factory) power supply is proposed. The required power is 0.8 MW on the 991 MHz frequency. The high-voltage electron gun produces electron bunches and puts them into the cylindrical resonator tuned to TE02 mode and operating frequency. Bunches produces RF field that takes energy from the following bunches and then energy transfer to the accelerating structure throw the tuned coupling system.
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WEPME068	Mitigating Noise Sources in MTCA.4 Electronics for High Precision Measurements	instrumentation, distributed, FPGA, simulation	2436
	U. Mavrič, M. Hoffmann, F. Ludwig, H. Schlarb DESY, Hamburg, Germany
	The RF field detection instrumentation plays a crucial role in modern accelerator performance. The most critical section is the transition from the analog signal processing to the digitalization. In this paper we present state of the art performance of COTS components and limitations imposed by crate-oriented solutions. We give recipes on how to optimize performance and present some of the recent results.
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WEPRI006	High Power RF Input Couplers and Test Stand for the BERLinPro Project	cavity, booster, SRF, linac	2487
	V.F. Khan, W. Anders, A. Burrill, J. Knobloch, A. Neumann HZB, Berlin, Germany
	Funding: Work supported by German Federal Ministry of Education and Research, Land Berlin, and grants of the Helmholtz Association The BERLinPro project, under construction at HZB, is a 100 mA, 50 MeV superconducting RF (SRF) energy recovery linac (ERL) being built to study the accelerator physics of operating a high current SRF ERL. For this high current operation, coaxial RF power couplers capable of handling 130 kW of power, c.w. at 1.3 GHz are required for both the SRF gun and booster cavities. In order to achieve this power level a coupler has been designed based on the high power coupler currently in use at the KEK-cERL. A key improvement that was made to the coupler was the modification of the coupler tip, termed a golf-tee. This modification is incorporated so as to achieve the desired coupling, Qext ~10⁵, with minimal coupler penetration into the beampipe. Herein, we discuss the RF design and properties of the high-power coaxial coupler for the gun as well as booster cavity of BERLinPro, along with the design of the test stand for conditioning a pair of couplers.
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WEPRI007	Booster Cavity and Fundamental Power Coupler Design Issues for BERLinPro	cavity, booster, SRF, emittance	2490
	A. Neumann, M. Abo-Bakr, W. Anders, A. Burrill, V.F. Khan, J. Knobloch, S. Wesch HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association HZB has started building the 50MeV, 100mA demonstrator energy-recovery-linac (ERL) facility BERLinPro. The high power injector system needs to deliver this beam at 6.5MeV by combining the energy gain of a 1.4 cell SRF photo-injector and three Cornell style 2-cell booster cavities. One booster cavity will be operated at zero-crossing for bunch energy chirping. Thus two booster cavities have to deliver 2MV each requiring a strong coupling with a loaded Q of 10⁵. To house the two envisaged KEK fundamental power couplers (FPC) with the cavity, the geometry was slightly modified. Further, to increase coupling and reduce transverse kick effects to the beam, a ”golf-tee” antenna tip was designed. This paper summarizes the SRF challenges for the booster cavities, the operational conditions and the modification to the KEK couplers, including tracking calculations to estimate the coupler kick effect to higher order.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI007
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WEPRI008	First Cavity Design Studies for the BESSY-VSR Upgrade Proposal	cavity, HOM, damping, impedance	2493
	A. Neumann, A. Burrill, P. Goslawski, A. Jankowiak, J. Knobloch, M. Ries, M. Ruprecht, A.V. Vélez, G. Wüstefeld HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung and Land Berlin Recently HZB proposed an upgrade of the 3rd generation synchrotron light source BESSY II allowing simultanous long and short pulse operation. For this scheme to work superconducting higher harmonic cavities of the fundamental 500 MHz at two frequencies need to be installed in the BESSY II storage ring. Given an appropiate choice of the higher harmonics the resulting gradient leads to a beating effect of the effective longitudinal focussing voltage at the stable fix points resulting in different bunch lengths in subsequent buckets. This project places stringent requirements on the cavity performance, as high accelerating fields, excellent HOM damping capabilities and high reliability as they will operate in a 300 mA 24/7 user facility. In this paper we describe the requirements for the cavity design and first designs steps. G. Wüstefeldt et al., Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proc. of IPAC'11, San Sebástian, Spain
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI008
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WEPRI009	Parameter Studies and Geometry Optimization on Superconducting Multicell RF Cavity Resonators	factory, cavity, HOM, RF-structure	2496
	B.D. Isbarn, B. Riemann, M. Sommer, T. Weis DELTA, Dortmund, Germany
	Funding: Work partly supported by the BMBF under contract No. 05K13PEB Modern accelerator concepts for high intensity electron beams often require superconducting multicell RF-cavity-resonators in circular accelerators (e.g. storage rings). Caused by strong beam-cavity interaction and due to high quality factors of superconducting RF-structures special care of lower order (LOM) and higher order (HOM) modes must be taken. Various numerical studies were performed to numerically calculate the dependence of different figures of merit (e.g. external quality factors Qext) with respect to the geometry parameters and cell number of the RF-structure, focused on the propagation and damping of low and higher order modes. To ease the numerical effort an optimization routine has been developed which automatically optimizes the geometry based on goal functions. In this context it turned out that cell geometries defined by spline functions have advantages compared to the standard elliptical parametrization regularly used. The number of free parameters is substantially reduced which facilitates the search for optimum solutions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI009
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WEPRI016	Status of the Vertical Testing of the XFEL Third Harmonic Cavity Series	cavity, HOM, linac, operation	2508
	J.F. Chen, M. Bertucci, A. Bosotti, M. Fusetti, C. Maiano, P. Michelato, L. Monaco, M. Moretti, C. Pagani, R. Paparella, P. Pierini, D. Sertore INFN/LASA, Segrate (MI), Italy
	The prototype cavities of the XFEL 3rd harmonic system at the XFEL injector have been tested vertically before their final integration into the He tank. The Vertical Test facility has been upgraded in preparation of the series and the results so far obtained are presented.
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WEPRI040	On the Optimal Design of Elliptical Superconducting Cavities	cavity, simulation, diagnostics, target	2565
	G. Costanza Lund University, Lund, Sweden
	In this paper a linear regression analysis is used to analyze the behavior of the inner cell of an elliptical cavity. The aim is to understand how the RF parameters are correlated to each other and how they are affected by the change of the geometric parameters. This is done by fitting the RF data to a linear model. The data is obtained by simulating a set of different inner cells automatically by the use of a script. The results are useful in several ways: first of all the analysis sheds light on the behavior of elliptical cavities, in particular on its limitations. The analysis is carried out in the framework of optimal design so it is useful for the cavity designer since it allows to choose the geometry at an early stage of the design. It is also possible to make predictions on the performance of the cavity which are in very good agreement with the simulations. Such predictions facilitate the design of the accelerator when choosing the type and number of cavities and when writing the specifications for the cavities to be used in the accelerator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI040
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WEPRI049	Optimization of Window Position on Diamond SCRF Cavities	cavity, operation, simulation, impedance	2592
	S.A. Pande, C. Christou DLS, Oxfordshire, United Kingdom
	The Diamond storage ring uses CESR type superconducting cavities. These cavities have a fixed coupling resulting in fixed Qext which is considerably higher than the optimum. We use 3 stub tuners to match the cavities under these non-optimum conditions. Diamond Cavity-1 will soon be refurbished. This opportunity could be used to lower the Qext on the cavity. One of the options is to modify the coupling tongue geometry along with a matching section. This may require cutting off the beam tube with the coupler for rework or it may need to be newly fabricated. We investigated another option to lower the Qext of the cavity by optimising the location of the window with respect to the cavity, maintaining the same coupling tongue geometry. The height of the waveguide on the vacuum side of the window differs from that of the coupling waveguide on the cavity resulting in a step. The location of window with respect to the cavity makes a significant difference to the ultimate Qext obtained after putting the window in place. In this paper we present the results of our numerical simulations comparing the present and the proposed window position under different operating conditions.
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WEPRI053	Phase Method of Measuring Cavity Quality Factor	cavity, simulation, resonance, data-analysis	2604
	O.S. Melnychuk, R.V. Pilipenko, Y.M. Pischalnikov, W. Schappert, D.A. Sergatskov Fermilab, Batavia, Illinois, USA
	Novel method for measuring intrinsic quality factor of superconducting RF (SRF) cavities using both amplitude and phase information of forward, reflected, and transmitted cavity signal is discussed. Advantages of the method in comparison with traditional types of cavity quality factor measurements are highlighted. Computer simulations and evaluation of uncertainties for the measurements are described. Analysis of data collected at vertical test facility for SRF cavities at Fermilab is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI053
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WEPRI057	RF Control and DAQ Systems for the Upgraded Vertical Test Facility at Fermilab	cavity, controls, interface, instrumentation	2612
	Y.M. Pischalnikov, R.H. Carcagno, F.L. Lewis, R. Nehring, R.V. Pilipenko, W. Schappert Fermilab, Batavia, Illinois, USA
	Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. The Fermilab Vertical Cavity Test Facility (VCTF) [1] is a used to test production cavities prior to their installation in cryomodules and to characterize the performance of research cavities as part of the extensive SRF cavity R&D program at FNAL. The performance of a variety of SRF cavities (325MHz, 650MHz, 1300MHz; bare and dressed) can be measured at VCTF. Recently FNAL upgraded the facility by adding two additional test stands (VTS2&3) in preparation for production of cavities for two new linear accelerators (LCLS II and PIP II). This paper provides an overview of the design features, technical parameters and experience with first operation of the upgraded RF control and DAQ systems.
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WEPRI065	SRF Material Performance Studies using a Sample Host Cavity	cavity, niobium, SRF, controls	2638
	D.L. Hall, D. Gonnella, M. Liepe, I.S. Madjarov Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	A sample-host TE-mode cavity developed at Cornell for the purposes of studying novel superconducting materials has undergone further testing using a niobium sample plate. In initial testing the peak field achieved on the sample plate was (45 ± 4.5) mT, although this was limited by the amount of input power available. New tests have been performed using both an improved RF power system and a temperature mapping system for precision measurements of surface resistance as a function of location on the sample plate. Results of the most recent test, in which the cavity achieved a peak sample plate field of (81 ± 4) mT using a high-RRR niobium sample plate, are presented and future work on the cavity is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI065
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WEPRI068	Conceptual Design of an Ideal Variable Coupler for Superconducting Radiofrequency 1.3 GHz Cavities	cavity, vacuum, scattering, Windows	2648
	C. Xu, S.G. Tantawi SLAC, Menlo Park, California, USA
	We present a new type of fundamental mode accelerator structure coupler. This coupler has a very simplified mechanical structure and is equipped with a novel vacuum window structure that allows the coupler to be divided into two parts. These two parts are fully thermally isolated, only coupled by thermal radiation. The rf power on the other hand get coupled perfectly from one part to the other. This is truly novel approach which is quite different than the conventional approach to this problem such as chock structure. The structure in general is slightly overmoded. We show that this structure can also be adopted to change the coupling coefficient and thus be tuned for an external Q. This could be of great utility for CW operation. We show the analytical and numerical calculation for a two window variable coupler.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI068
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WEPRI078	Development of a Quarter-wave Coaxial Coupler for 1.3 GHz Superconducting Cavities	cavity, niobium, HOM, SRF	2675
	Y. Xie, A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Superconducting ILC-type cavities have an rf coupler that is welded on. A detachable coupler will reduce conditioning time (can be conditioned separately), reduce cost and improve reliability. The problem with placing an extra flange in the superconducting cavity is creating a possible quench spot. Euclid Techlabs LLC designed a coupler and optimized its geometry that yielding an area on the surface with zero magnetic field (hence zero surface current). By placing a flange in that area we are able to avoid disturbing surface currents that typically lead to a quench. The coupler is optimized to preserve the axial symmetry of the cavity and rf field. The rf test results of this type coupler with a 1.3 GHz ILC-type single-cell cavity at Fermilab will be reported and discussed.
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THOBA02	Status of the Emittance Transfer Experiment Emtex	emittance, solenoid, quadrupole, injection	2798
	M.T. Maier, L. Groening, C. Mühle, I. Pschorn, P. Rottländer, C. Will, C. Xiao GSI, Darmstadt, Germany M. Chung Fermilab, Batavia, Illinois, USA
	In order to improve the injection efficiency of the round UNILAC heavy ion beam into the asymmetric acceptance of the SIS18 it would be of great advantage to decrease the horizontal emittance by a so called emittance transfer to the vertical plane. In this contribution the present status of the emittance transfer experiment EMTEX at GSI will be reported. A short introduction about the theoretical background of the technique will be given, while the main part is dedicated to the practical solutions setting up a test beam line at GSI. Finally, the results of a first commissioning beam time will be presented. The scheduled beam time to apply the emittance transfer technique foreseen in spring 2014 had to be shifted to calendar week 26 in 2014, just after this conference, as some components have not been delivered in time by the contractor. The results and comparison to the theoretical predictions you may find in later publications.
	Slides THOBA02 [1.928 MB]
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THPRO079	Quantitative Analysis of Trapping Probability for Quasi-integrable Two-degree of Freedom Maps	resonance, simulation, extraction, synchrotron	3065
	M. Giovannozzi, C. Hernalsteens, J. Williams CERN, Geneva, Switzerland A. Bazzani Bologna University, Bologna, Italy C. Hernalsteens EPFL, Lausanne, Switzerland
	A key ingredient for the Multi-Turn Extraction (MTE) at the CERN Proton Synchrotron is the beam trapping in stable islands of transverse phase space. In a previous paper a method allowing analytical estimation of the fraction of beam trapped into resonance islands as a function of the Hamiltonian parameters has been presented. Such a method applies to one-degree of freedom models of betatronic motion. In this paper, the analysis is extended to the more realistic and challenging case of two-degree of freedom systems, in which the interplay between the horizontal and vertical motion is fully included. Numerical simulations are presented and the results are discussed in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO079
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THPME011	First Coupled CH Power Cavity for the FAIR Proton Injector	cavity, linac, proton, alignment	3232
	R. M. Brodhage, G. Clemente, W. Vinzenz GSI, Darmstadt, Germany R. M. Brodhage, U. Ratzinger IAP, Frankfurt am Main, Germany
	For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. The main acceleration of this room temperature linac will be provided by six CH cavities operated at 325 MHz. Each cavity will be powered by a 2.5 MW Klystron. For the second acceleration unit from 11.5 MeV to 24.2 MeV a 1:2 scaled model has been built. Low level RF measurements have been performed to determine the main parameters and to prove the concept of coupled CH cavities. In 2012, the assembly and tuning of the first power prototype was finished. Until then, the cavity was tested with a preliminary aluminum drift tube structure, which was used for precise frequency and field tuning. In 2013 the final drift tube structure has been welded inside the main tanks and the preparation for copper plating has taken place. This paper will report on the main tuning and commissioning steps towards that novel type of DTL and it will show the latest results measured on a fully operational CH proton cavity shortly before copper plating.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME011
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THPME016	Experimental Results on SCDTL Structures for Protons	proton, beam-transport, DTL, rfq	3247
	L. Picardi, A. Ampollini, G. Bazzano, P. Nenzi, C. Ronsivalle, V. Surrenti, M. Vadrucci ENEA C.R. Frascati, Frascati (Roma), Italy F. Ambrosini URLS, Rome, Italy
	The medium-energy section of the proton linear accelerator for radiotherapy under realization in the framework of the TOP-IMPLART Project consists in a high frequency 7-35 MeV SCDTL (Side Coupled Drift Tube Linac) structure. The structure, made of 4 modules supplied by one klystron, has been completely designed. The first module up to 11.6 MeV has been built and is under commissioning at ENEA-Frascati and the second and third modules are under realization. The paper describes the system and presents the main results of the experimental activity on this part of the accelerator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME016
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THPME017	Electromechanical Analysis of SCDTL Structures	cavity, proton, feedback, linac	3250
	M. Ciambrella, F. Cardelli, M. Migliorati, A. Mostacci, L. Palumbo URLS, Rome, Italy L. Ficcadenti, V. Pettinacci INFN-Roma, Roma, Italy L. Picardi, C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma), Italy
	The Side Coupled Drift Tube Linac (SCDTL) is a 3 GHz accelerating structure for proton therapy linac designed for TOP-IMPLART, an Intensity Modulated Proton Linear Accelerator for Radio-Therapy. The structure is made up of short DTL accelerating tanks for low current proton beams, coupled by side coupling cavities. The purpose of this paper is to report on the analysis of electromagnetic and the thermo-mechanical behavior for the SCDTL structure. The 3D electromagnetic analysis is used to derive the power dissipation on the structure; then one can infer the temperature distribution and deformation field in order to eventually evaluate their feedback on the electromagnetic properties of the structure as, for instance, the cavity resonant frequency shift. Such a "multi-physics'' analysis has been performed for different supporting stem geometries in order to optimize the shunt impedance and the R/Q for SCDTL cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME017
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THPME018	Global Search Methods for Electromagnetic Optimization of Compact Linac Tanks	linac, proton, cavity, HOM	3253
	O. Losito, V. Dimiccoli, G. Rutigliani ITEL, Ruvo di Puglia, Italy L. De Palma, F. Prudenzano Politecnico di Bari (DEI), Bari, Italy
	We shows the optimization of a five cell tank to be included as first multi-cavity within a LINAC section accelerating a proton beam from 7 MeV to higher energies, useful for proton therapy. The tank performance depends on a set of physical (beam characteristics) and geometrical parameters (radius and lengths of accelerating and coupling cavities, radius and thickness of the coupling holes among accelerating cells, the radius and the thickness of the coupling holes between off-axis coupling cells and accelerating ones). PSO (Particle Swarm Optimization) and ACO (Ant Colony Optimization) have been used as approaches for the electromagnetic optimization. The model used for the fitness calculation takes into account all the most important effects occurring in the tank coupled cavities loaded by the proton beam. The codes based on PSO and ACO have enabled the global and stochastic identification of about ten optimized parameters. The design goodness has been tested via Particle and Microwave CST Studio © simulation. The optimized tank accelerates the proton beam input energy from Ein=7 MeV to about Eout= 8.2 MeV. These values, well agree with other designs reported in literature.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME018
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THPME055	RF Tuning of the IPHI RFQ	rfq, dipole, quadrupole, operation	3355
	O. Piquet, M. Desmons, A. France CEA/DSM/IRFU, France
	The construction of IPHI (High Power Proton Accelerator) is in its final step of installation. The RFQ will accelerate beam up to 100 mA with energy up to 3 MeV. The RFQ, made of six modules, one meter each, is of the four-vane type. The RFQ is divided in 2-meter long segments with capacitive coupling. It is also equipped with 96 fixed tuners and four waveguide RF ports located in the fourth module. This paper describes the procedure used to tune the accelerating field and power couplers of the RFQ.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME055
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THPME059	Preparation of the Coupled RFQ-IH-cavity for FRANZ	rfq, DTL, cavity, operation	3367
	M. Heilmann, C. Claessens, O. Meusel, D. Mäder, U. Ratzinger, A. Schempp, M. Schwarz IAP, Frankfurt am Main, Germany
	The Frankfurt neutron source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra-short neutron pulses at high intensities and repetition rates. The neutrons will be produced using the 7Li(p, n)7Be reaction induced by a proton beam. The 175 MHz IH-type drift tube linac with 8 gaps succeeds a 4-rod-RFQ. Together they form a coupled linac combination with a length of 2.3 m and accelerate the protons from 120 keV to 2.03 MeV. As the RF losses add up to 200 kW, the cooling of both accelerators is a central challenge. The RFQ-IH combination is powered by a radio frequency amplifier, which couples the RF power into the RFQ. The two structures are connected via inductive coupling. The initial beam operation of the accelerators is configured for 50 mA in cw mode. The IH-components were fabricated, RF tuning measurements are underway. The RFQ and the IH-DTL will be conditioned separately and then be connected, aiming for a beam operation at the end of 2014. A main challenge in fabrication was the precise welding required for the water cooled drift tubes and stems.
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THPME133	Bunch Length Measurement with 2-Cell RF-Deflector at Waseda University	electron, cavity, gun, cathode	3556
	T. Takahashi, Y. Nishimura, M. Nishiyama, K. Sakaue, M. Washio Waseda University, Tokyo, Japan T. Takatomi, J. Urakawa KEK, Ibaraki, Japan
	We have been studying on a system to measure the length of electron bunch generated by a photocathode rf electron gun at Waseda University. We adopted the rf-deflector system which can convert the longitudinal distribution to transverse by sweeping the electron bunch. By using HFSS, we optimized the design of the 2 cell rf-deflector which is operating on π-mode, dipole (TM110-like) mode at 2856 MHz. The fabrication and the tuning of the rf deflector have successfully processed. We have installed the rf-deflector in the accelerator system of Waseda University, and performed the measurement of the bunch length. It is confirmed that this rf-deflector has the temporal resolution of 167fs with 700kW supply when the beam energy is 4.8MeV. This means that our rf-deflector system has possibility to measure the ultra-short bunch length. In this conference, the rf-deflector system in Waseda University, the result of the bunch length measurement, the performance of the rf-deflector and the future plan will be reported. Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690 and the Quantum Beam Technology Program of MEXT.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME133
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THPME163	Beam Size and Emittance Reconstruction in the RMTL of Future Linear Colliders	emittance, diagnostics, target, optics	3647
	A. Faus-Golfe, J. Resta-López IFIC, Valencia, Spain
	Funding: Work supported by FPA2010-21456-C02-01 Precise and fast beam size measurement and emittance reconstruction in the different subsystems and transfer lines of the Future Linear Colliders (ILC and CLIC) will be essential for beam tuning in order to achieve the required luminosity. In this paper we investigate the feasibility of using a multi-Optical Transition Radiation (m-OTR) system for fast transverse beam size measurement, emittance reconstruction and coupling correction in the Ring to Main Linac (RTML) of the FLCs. Diagnostic sections of the RTML have been matched to the optimum optical conditions for emittance reconstruction. The necessary requirements for the OTR monitors to be placed in the RTML are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME163
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THPRI030	Progress Towards Completion of the MICE Demonstration of Muon Ionization Cooling	emittance, cavity, solenoid, lattice	3831
	D.M. Kaplan, P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA A.J. Dobbs Imperial College of Science and Technology, Department of Physics, London, United Kingdom P. Snopok Fermilab, Batavia, Illinois, USA
	Funding: DOE, NSF, STFC, INFN, CHIPP and several others The Muon Ionization Cooling Experiment (MICE) at the Rutherford Appleton Laboratory aims to demonstrate ~10% ionization cooling of a muon beam, by its interaction with low-Z absorber materials followed by restoration of longitudinal momentum in RF linacs. MICE Step V will provide the flexibility for a thorough exploration and characterization of the performance of ionization cooling. Step V will include four RF cavities to provide 8 MV/m gradient in a strong magnetic field. This entails an RF drive system to deliver 2 MW, 1 ms pulses of 201 MHz frequency at 1 Hz repetition rate, the distribution network to deliver 1 MW to each cavity with correct RF phasing, diagnostics to determine the gradient and the muon transit phase, and development of the large diameter magnets required in order to keep the muons focused through the linacs. Progress towards the completion of Step V is described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI030
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THPRI035	Design and Simulation of Side Coupled Six MeV Linac for X-Ray Cargo Inspection	cavity, acceleration, simulation, electron	3844
	S. Ahmadiannamin, F. AbbasiDavani, R. Ghaderi, F. Ghasemi sbu, Tehran, Iran M. Lamehi Rashti IPM, Tehran, Iran S. Zarei Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
	Using in X-ray cargo inspection is one of most applications of linear accelerators. This paper represents design and simulation of Side Coupled Six MeV cavity. The electromagnetic simulation of structure was carried out in the SUPERFISH and CST Microwave studio. 2.3 MW input power is considered according to MG5193 magnetron. The coupling coefficient is calculated equal to 3% for stabilization of accelerator operation against environmental and mechanical errors effects.
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THPRI048	Design of an Accelerating Tube for a Standing-wave Accelerator based on Genetic Algorithm’s Optimal Calculation	impedance, electron, simulation, radiation	3875
	Z.X. Tang USTC, Hefei, Anhui, People's Republic of China Y.J. Pei USTC/NSRL, Hefei, Anhui, People's Republic of China
	A compact medical standing-wave (SW) electron accelerating tube has been designed that operating frequency is 2998MHz, operating mode is π/2, final energy is 6MeV and beam current is 100mA based on genetic algorithm (GA)’s optimal calculation. It employed a bi-periodic structure with nose cone shape. We performed the simulation experiment which proved that GA was feasible and gave a set of geometric parameter with higher shunt impedance. We performed tuning of the whole tube by CST MICROWAVE STUDIO and SUPERFISH and calculation of beam dynamics by ASTRA and Parmela in this paper. The total length of the tube is less than 300mm.
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THPRI051	Fabrication and Tests of the Re-buncher Cavities for the LIPAc Deuteron Accelerator	cavity, vacuum, pick-up, simulation	3884
	D. Gavela, P. Abramian, J. Calero, A. Guirao, J.L. Gutiérrez, E. Molina Marinas, I. Podadera, L. Sánchez, F. Toral CIEMAT, Madrid, Spain
	Funding: This work has been partially funded by the Spanish Ministry of Economy and Competitiveness under project AIC-A-2011-0654 Two re-buncher cavities will be installed at the Medium Energy Beam Transport (MEBT) of the LIPAc accelerator, presently being built at Rokkasho (Japan). They are IH-type cavities with 5 gaps and will provide an effective voltage of 350 kV at 175 MHz. The cavity consists of a cylindrical main body and two endplates in stainless steel with an internal copper coating. The stems and drift tubes are machined from bulk OFE copper. The fabrication techniques for the cooling pipes, the input coupler and the pick-up are presented. Material choices and fabrication process are discussed. The first re-buncher is already fabricated. RF low power tests have been made to measure resonant frequency, S-parameters and Q-factor before and after the copper plating. The electric field map has also been measured with the bead-pull method.
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THPRI075	S-Band Structure Study for the MaRIE Project	wakefield, dipole, impedance, linac	3940
	Z. Li, C. Adolphsen, M.V. Fazio, S.G. Tantawi, L. Xiao SLAC, Menlo Park, California, USA
	Funding: Work was supported by the US Department of Energy through the LANL/LDRD Program. The Matter-Radiation Interactions in Extremes (MaRIE) facility proposed at LANL utilizes a 20-GeV electron linac to drive a 50-keV XFEL. Experimental requirements drive a need for multiple photon bunches over time durations of about 10 microsecond produced by a bunch train of interleaving 0.1 nC very low-emittance bunches with 2-nC electron bunches. The linac is required not only to provide high gradient and high efficient acceleration, but also a controlled wakefield profile to maintain the beam quality. In this paper, we explore the feasibility of using the S-Band technology to meet such acceleration requirements. We will present the design optimization and comparison of S-Band structures based on different design considerations.
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THPRI080	The New Design for Capture Cavity of CEBAF	cavity, electron, acceleration, simulation	3955
	S. Wang, J. Guo, R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	In CEBAF, the electron beam from the injector must be sufficiently relativistic to match a 1 GeV recirculated beam in the first linac. The electron beam is produced with a ~130 keV electron gun, then accelerated by a room temperature, graded-beta standing wave linac, capture section, from 130 keV to 510 keV before enters two 5-cell superconducting RF cavities for further acceleration. Present capture cavity is a 5-cell side-coupled cavity. We designed a new slot-coupled cavity which has lower power consumption and simpler structure.
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THPRI103	Improvement of the Run-time of 35 mbar Helium Gas Pumping Units for the Superconducting Linear Accelerator S-DALINAC	operation, controls, experiment, vacuum	4019
	J. Conrad, F. Hug, T. Kürzeder, N. Pietralla TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG through SFB 634 The superconducting Darmstadt linear accelerator S-DALINAC has been designed to provide electron beams of up to 130 MeV for nuclear and astrophysical experiments. The accelerating cavities are operated in a liquid helium bath at 2 K. To achieve this temperature the cryostat has to be pumped down to a pressure of 35 mbar which was done by a system of pumping units connected in series, when the accelerator started its operation in 1991. In 2005 this system was replaced by four parallel switched pumping stations. In the first three years of their operation, the reliability of the accelerator was very poor due to repeated breakdowns of the pumping stations caused by overheating. In addition the high temperatures lead to an early decay of the gaskets used. The problem was solved by installing oil cooling systems and more appropriate shaft sleeves at the pumping stations. We will report on the technical efforts we made and thereby further increased the availability of the accelerator significantly. Also we will give a review on our experiences in maintenance procedures.
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FRYCA01	Options and Prospects for the Future of Accelerator-based High-energy Physics	collider, detector, proton, luminosity	4079
	F. Gianotti CERN, Geneva, Switzerland
	Recent results from the LHC and other facilities have significantly impacted the landscape of particle physics. This talk summarises the main outstanding questions in high-energy physics and the strategy to address them. Options for future accelerator facilities and their motivations are discussed.
	Slides FRYCA01 [16.139 MB]
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Paper

Title

Other Keywords

Page

MOZA01

Ultralow Emittance Beam Production based on Doppler Laser Cooling and Coupling Resonance

laser, ion, simulation, solenoid

28

A. Noda, M. Nakao
NIRS, Chiba-shi, Japan
M. Grieser
MPI-K, Heidelberg, Germany
Z.Q. He
FRIB, East Lansing, Michigan, USA
Z.Q. He
TUB, Beijing, People's Republic of China
K. Jimbo
Kyoto University, Kyoto, Japan
H. Okamoto, K. Osaki
HU/AdSM, Higashi-Hiroshima, Japan
A.V. Smirnov
JINR, Dubna, Moscow Region, Russia
H. Souda
Gunma University, Heavy-Ion Medical Research Center, Maebashi-Gunma, Japan
H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
Y. Yuri
JAEA/TARRI, Gunma-ken, Japan

Funding: Work supported by Advanced Compact Accelerator Development project by MEXT of Japan. It is also supported by GCOE project at Kyoto University, “The next generation of Physics-Spun from Universality"
Doppler laser cooling has been applied to low-energy (40 keV) Mg ions together with the resonant coupling method* at the S-LSR at ICR, Kyoto University,. The S-LSR storage ring has a high super periodicity of 6, which is preferable from the beam dynamical point of view. At S-LSR one dimensional ordering of proton beam was already realized for the first time**. Active three dimensional laser cooling has been experimentally demonstrated for ions with un-negligible velocity (v/c=0.0019, where c is the light velocity) for the first time. Utilizing the above mentioned characteristics of S-LSR, an approach to realize ultralow emittances has been pursuit. To suppress heating effects, due to intra-beam scattering, the circulating ion beam intensity was reduced by scraping and beam emittances of 1.3·10^-11 pi m·rad and 8.5·10^-12 pi m·rad (normalized) have been realized for the horizontal and vertical directions, respectively with the 40 keV Mg ion beam at a beam intensity of ~10⁴, which is the lowest emittance ever attained by laser cooling. From MD computer simulations, it is predicted that reduction of the ion number to about 10³ is needed to realize a crystalline string.
* H. Okamoto, A.M. Sessler, D. Moehl, Phys. Rev. Lett. 72, 397 (1994).
** T. Shirai et. al., Phys. Rev. Lett. 98, 204801 (2007).

Slides MOZA01 [13.336 MB]

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MOZA02

Advanced RF Design and Tuning Methods of RFQ for High Intensity Proton Linacs

rfq, linac, dipole, operation

34

A. France
CEA/IRFU, Gif-sur-Yvette, France

The injector of high intensity linacs includes a Radio Frequency Quadrupole (RFQ) which must sustain high surface fields and thermal effects while accelerating intense low energy beams. For this purpose, the modelisation, realisation and tuning of accurate field laws is mandatory to preserve beam emittances and minimize beam losses. This presentation reviews the progress of advanced methods for the RF design, RF measurements during fabrication and final tuning of RFQ for high intensity linacs. It reports the ongoing developments on the injectors of high intensity demonstrators and of the linacs under construction such as SPIRAL2, LINAC4 or IFMIF-EVEDA.

Slides MOZA02 [2.026 MB]

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MOPRO011

Employing Twin Crabbing Cavities to Address Variable Transverse Coupling of Beams in the MEIC*

electron, solenoid, proton, cavity

80

A. Castilla
DCI-UG, León, Mexico
A. Castilla, J.R. Delayen, V.S. Morozov, T. Satogata
JLab, Newport News, Virginia, USA
A. Castilla, J.R. Delayen, V.S. Morozov, T. Satogata
ODU, Norfolk, Virginia, USA

Funding: *Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The design strategy of the Medium Energy Electron-Ion Collider (MEIC) at Jefferson Lab contemplates both matching of the emittance aspect ratios and a 50 mrad crossing angle along with crab crossing scheme for both electron and ion beams over the energy range (√s=20-70 GeV) to achieve high luminosities at the interaction points (IPs). However, the desired locations for placing the crabbing cavities may include regions where the transverse degrees of freedom of the beams are coupled with variable coupling strength that depends on the collider rings’ magnetic elements (solenoids and skew quadrupoles). In this work we explore the feasibility of employing twin rf dipoles that produce a variable direction crabbing kick to account for a range of transverse coupling of both beams.

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MOPRO027

Measurements and Laboratory Tests on a Prototype Stripline Kicker for the CLIC Damping Rings

impedance, simulation, kicker, damping

125

C. Belver-Aguilar, A. Faus-Golfe
IFIC, Valencia, Spain
M.J. Barnes, H.A. Day
CERN, Geneva, Switzerland
F. Toral
CIEMAT, Madrid, Spain

The Pre-Damping Rings (PDRs) and Damping Rings (DRs) of CLIC are required to reduce the beam emittances to the small values required for the main linacs. The injection and extraction, from the PDRs and DRs, are performed by kicker systems. To achieve both low beam coupling impedance and reasonable broadband impedance matching to the electrical circuit, striplines have been chosen for the kicker elements. Prototype striplines have been built: tests and measurements of these striplines have started. The goal of these tests is to characterize, without beam, the electromagnetic response of the striplines. The tests have been carried out at CERN. To study the signal transmission through the striplines, the measured S-parameters have been compared with simulations. In addition, measurements of longitudinal beam coupling impedance, using the coaxial wire method, are reported and compared with simulations.

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MOPRO032

Upgrades to the LHC Injection and Beam Dumping Systems for the HL-LHC Project

injection, kicker, dumping, impedance

141

J.A. Uythoven, M.J. Barnes, B. Goddard, J. Hrivnak, A. Lechner, F.L. Maciariello, A. Mereghetti, A. Perillo Marcone, N.V. Shetty, G.E. Steele
CERN, Geneva, Switzerland

The HL-LHC project will push the performance of the LHC injection and beam dumping systems towards new limits. This paper describes the systems affected and presents the new beam parameters for these systems. It also describes the studies to be performed to determine which sub-components of these systems need to be upgraded to fulfill the new HL-LHC requirements. The results from the preliminary upgrade studies for the injection absorbers TDI are presented.

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MOPRO048

Update on Sirius, the New Brazilian Synchrotron Light Source

emittance, lattice, insertion, insertion-device

191

L. Liu, A.P.B. Lima, N. Milas, A.H.C. Mukai, X.R. Resende, A.R.D. Rodrigues, F. H. de Sá
LNLS, Campinas, Brazil

Sirius is a 3 GeV synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). The electron storage ring uses the multi-bend-achromat approach (5BA in this case) to achieve a very low beam emittance of 0.28 nm.rad. The 518 m circumference contains 20 straight sections of alternating 6 and 7 meters in length, to be used for insertion devices as well as injection and RF systems. The 5BA cell is modified to accommodate a thin high field dipole (for 1.4˚ deflection) in the center of the middle bend producing hard X-ray radiation (12 keV critical energy) with a modest contribution to the total energy loss. This high field dipole (2.0 T) will be made of permanent magnet material, whereas the low field (0.58 T) ones, responsible for the main beam deflection, will be electromagnetic. Many challenges are associated with this kind of lattice, including both in beam dynamics and in accelerator engineering, that require R&D on new techniques. In this paper we discuss the main issues and achievements for Sirius during the last year.

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MOPRO058

The Low-alpha Lattice and Bunch Length Limits at BESSY-VSR

radiation, storage-ring, optics, dipole

216

P. Goslawski, M. Ries, M. Ruprecht, G. Wüstefeld
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung and Land Berlin.
An upgrade of the BESSY II ring to a Variable bunch length Storage Ring BESSY^VSR has been recently proposed *, by introducing strongly focusing superconducting cavities. This will allow to store simultaneously long and short bunches. In the regular user optics, bunch lengths of 15 ps (rms) and down to 1.5 ps (rms) are expected. Bunches as short as 300 fs (rms), close to the bunch length limit, and a ring current of 3.5 mA at the bunch bursting threshold can be provided by using a modified low-alpha optics. This presentation will discuss the properties of the low-alpha optics and intrinsic bunch length limits, given by coupling effects of the longitudinal and horizontal plane.
* G. Wüstefeld, A. Jankowiak, J. Knobloch, M.Ries, "Simultaneous Long and Short Electron Bunches in the BESSYII Storage Ring", Proceedings of IPAC2011, San Sebastian, Spain.

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MOPRO076

Elettra Status and Upgrades

operation, controls, dipole, emittance

261

E. Karantzoulis, A. Carniel, S. Krecic
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with the latest studies and upgrades.

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MOPRO077

Betatron Coupling Numerical Study at Elettra

emittance, betatron, quadrupole, lattice

264

S. Di Mitri, E. Karantzoulis
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Elettra lacks skew quadrupoles and the coupling is controlled via the vertical orbit. Elettra has typical operational coupling of 1%, values as low as 0.3% were reached but however not easily established and reproducible. In order to control the coupling in a reproducible manner skew quadrupoles must be installed. Simulations of the betatron coupling and correction for the Elettra synchrotron light source were performed and are here presented. The numerical study is based on measured machine misalignments and carried out with the ELEGANT particle tracking code. The inclusion of families of skew quadrupoles in the existing lattice is investigated and shown to be conclusive for the coupling correction at the level of 0.1%.

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MOPME014

Automated Mode Recognition Algorithm for Accelerating Cavities

cavity, simulation, polarization, dipole

409

K. Brackebusch, T. Galek, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Work supported by Federal Ministry for Research and Education BMBF under contract 05K13HR1.
Eigenmode simulations of accelerating structures often involve a large number of computed modes that need to be catalogued and compared. In order to effectively process all the information gathered from eigenmode simulations a new algorithm was developed to automatically recognize modes’ field patterns. In this paper we present the principles of the algorithm and investigate its applicability by means of different single and multi cell cavities. The highest achievable order of correctly recognized modes is of particular interest.

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MOPME066

Development of 400 kA Pulsed Power Supply for Magnetic Horn at FAIR Antiproton Target

antiproton, radiation, operation, power-supply

517

S.S. Mohite, R. Hettinger, K. Knie, I.J. Petzenhauser
GSI, Darmstadt, Germany

This report presents an overview of the magnetic horn and its pulsed power system at the upcoming FAIR (Facility for Antiproton and Ion Research) complex at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. In the planned antiproton (pbar) separator scheme a magnetic horn will be used as a device for collection and focusing of highly divergent antiprotons emerging from the target with energies around 3 GeV and within a cone of about 80 mrad .To achieve the desired focusing effect, the horn needs to be powered with a current pulse of 400 kA peak amplitude at the same repetition rate as the primary proton beam, i.e. 0.1 Hz. In future, operation up to 0.2 Hz is planned without major design alterations. Due to civil construction and radiation protection limitations, possible technical realization of this system has some key design issues. The aim is to develop a reliable and efficient magnetic horn system for effective focusing of antiprotons by producing a very strong pulsed magnetic field.

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MOPME071

Configurations and Applications of Saturable Pulse Transformers in High Power Pulse Modulation

high-voltage, experiment, plasma, controls

532

J. Liu, J. Gao, X.J. Ge, J. He, Y. Zhang
NUDT, Changsha, People's Republic of China

Saturable pulse transformers (SPTs) based on multiple batches of windings in parallel combination and coaxial cylindrical conductors are presented. The proposed SPT can be employed as the transformer and magnetic switch simultaneously for pulse capacitor or high-voltage pulse modulator of several hundred kV range. The SPT, with important features such as auto-resetting of core, high step-up ratio and low saturation inductance, achieves a compact integration of common transformer and magnetic switch. In the SPT, The physical suppression effect caused by reversed magnetic coupling mechanism among primary and secondary windings can reduce the saturation inductance of the SPT windings to a level lower than their structure inductances, which helps to achieve a magnetic switch with low saturation inductance. The proposed SPTs were applied in a high power pulse modulator based on a helical Blumlein pulse forming line (HBPFL). When the SPT played as a pulse transformer, the HBPFL can be charged to 200 kV. When the SPT played as a main magnetic switch of the HBPFL, it helped to form a quasi-square voltage pulse with amplitude of 180 kV，pulse duration of 130 ns, rise time of 60 ns.

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MOPME081

A Stripline Kicker Driver for the Next Generation Light Source

kicker, high-voltage, simulation, impedance

559

F.M. Niell, N. Butler, M.P.J. Gaudreau, M.K. Kempkes, J. Kinross-Wright
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: US Department of Energy, Award DE-SC00004255
Diversified Technologies, Inc. (DTI) assembled a prototype pulse generator capable of meeting the original specifications for the Next Generation Light Source (NGLS) fast deflector. The ultimate NGLS kicker driver must drive a 50 Ω terminated Transverse Electromagnetic (TEM) deflector blade at 10 kV, with flat-topped pulses and a sustained repetition rate of 100 kHz. Additional requirements of the specification include a 2 ns rise time (10 – 90%), a highly repeatable flattop with pulse width from 5 – 40 ns, and a fall time less than 1 μs (down to 10-4 of the peak value). The driver must also effectively absorb high-order mode signals emerging from the deflector itself. It is envisioned that a scintilla of deflection will be imparted by a symmetric pair of shaped parallel deflection blades, pulsed in opposition at 10 kV. Within the guide, each TEM wave produced by the two pulse generators traverses the guide synchronously with the selected (relativistic) charge packet. The DTI team has designed and demonstrated the key elements of a solid state kicker driver capable of meeting the NGLS requirements, with possible extension to a wide range of fast-pulse applications.

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MOPRI008

A Compact 2.45 GHz Microwave IOn Source Based High Fluence Irradiation Facility at IUAC, Delhi

ion, plasma, ion-source, extraction

592

N. Kumar, R. Ahuja, R.N. Dutt, D. Kanjilal, P.S. Lakshmy, Y. Mathur, G.O. Rodrigues
IUAC, New Delhi, India

A compact 2.45 GHz microwave ion source based low energy ion been facility has been developed for performing various experiments in material science and for studies related to plasma physics. The design of the compact microwave source is based on a tunable permanent magnet configuration and is powered by a 2 kW magnetron [1,2]. The double walled, water cooled stainless steel plasma chamber and ridge waveguide have been fabricated using the latest ‘LaserCUSING’ technique. The electron energy distribution functions have been measured in a similar low frequency ion source and validated by model calculations [1]. Extraction of the beam can also be performed at very low voltages in the order of hundreds of volts with high intensities by nullifying the space charge effects with the secondary electrons. The facility will be used for ion implantation, phase formation, surface etching and pattering experiments. The design aspects of the microwave ion source and low energy beam transport system will be presented.
* “Studies on the effect of the axial magnetic field on the x-ray bremsstrahlung in a 2.45 GHz permanent magnet microwave ion source” Narender Kumar et. al. accepted for publication in RSI.

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MOPRI033

Quasi-traveling Wave Side Couple RF Gun Commissioning for SuperKEKB

gun, cavity, emittance, cathode

667

T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou
KEK, Ibaraki, Japan

We are developing a new RF gun for SuperKEKB. High-charge low-emittance electron and positron beams are required for SuperKEKB. We will generate 7.0 GeV electron beam at 5 nC 20 mm-mrad by J-linac. In this linac, a photo cathode S-band RF gun will be used as the electron beam source. For this reason, we are developing an advanced RF gun. New RF gun which has two side coupled standing wave field is developed. We call it quasi traveling wave side couple RF gun. This gun has a strong focusing field at the cathode and the acceleration field distribution also has a focusing effect. Beam commissioning has been started with the new RF gun. I will report the result of beam commissioning.

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MOPRI043

Study of a C-band Standing-wave Gun for the SwissFEL Injector

gun, cathode, solenoid, emittance

698

M. Schaer, S. Bettoni, A. Citterio, P. Craievich, M. Negrazus, L. Stingelin, R. Zennaro
PSI, Villigen PSI, Switzerland

The baseline design of the SwissFEL injector foresees the "PSI Gun 1", a 2.6-cell RF photo-cathode gun operating at S-band frequency, as the electron source. In this paper a new design is presented where a 5.6-cell C-band gun could replace the PSI Gun 1 with no impact on the rest of the injector setup. A conservative maximum gradient of 135 MV/m at the cathode is assumed which drives the electron beam faster into the relativistic regime and therefore allows to tolerate larger charge densities. The presented solution also foresees a coaxial RF coupling from the cathode side in order to place the gun solenoid as near to the photo-cathode as possible, improving the emittance compensation. Astra simulations showed that the transverse beam brightness can be doubled before the first bunch compressor preserving the low transverse emittance value as compared to the current design for the S-band injector configuration of SwissFEL.

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TUOAB01

Computation of Eigenmodes in Long and Complex Accelerating Structures by Means of Concatenation Strategies

cavity, factory, HOM, FEL

947

T. Flisgen, J. Heller, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: This research was partially funded by the EuCARD project which is co-funded by European Commission 7th in Framework Programme (FP7).
The computation of eigenmodes for complex accelerating structures is a challenging and important task for the design and operation of particle accelerators. Discretizing long and complex structures to determine its eigenmodes leads to demanding computations typically performed on super computers. This contribution presents an application example of a method to compute eigenmodes and other parameters derived from these eigenmodes for long and complex structures using standard workstation computers. This is accomplished by the decomposition of the complex structure into several single segments. In a next step, the electromagnetic properties of the segments are described in terms of a compact state space model. Subsequently, the state space models of the single structures are concatenated to the full structure. The results of direct calculations are compared with results obtained by the concatenation scheme in terms of computational time and accuracy.

Slides TUOAB01 [1.781 MB]

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TUPRO018

Prospects for the LHC Optics Measurements and Corrections at Higher Energy

optics, software, GUI, quadrupole

1046

R. Tomás, T. Bach, J.M. Coello de Portugal, V. Kain, M. Kuhn, A. Langner, Y.I. Levinsen, K.S.B. Li, E.H. Maclean, N. Magnin, V. Maier, M. McAteer, T. Persson, P.K. Skowroński, R. Westenberger
CERN, Geneva, Switzerland
E.H. Maclean
JAI, Oxford, United Kingdom
S.M. White
BNL, Upton, Long Island, New York, USA

LHC will resume operation in 2015 at 6.5 TeV. The higher energy allows for smaller IP beta functions, further enhancing the optics errors in the triplet quadrupoles. Moreover the uncertainty in the calibration of some quadrupoles will slightly increase due to saturation effects. The complete magnetic cycle of the LHC will take longer due to the higher energy and extended squeeze sequence. All these issues require more precise and more efficient optics measurements and corrections to guarantee the same optics quality level as in 2012 when a 7% peak beta-beating was achieved. This paper summarizes the on-going efforts for achieving faster and more accurate optics measurements and corrections.

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TUPRO035

Vertical Emittance at the Quantum Limit

emittance, quadrupole, storage-ring, sextupole

1096

R.T. Dowd, Y.E. Tan
SLSA, Clayton, Australia
K.P. Wootton
The University of Melbourne, Melbourne, Victoria, Australia

Further reduction of betatron coupling and vertical dispersion in the storage ring of the Australian Synchrotron Light Source has resulted in the achievement of a beam vertical emittance that is now dominated by the intrinsic quantum effects. This paper will detail the key elements in achieving a vertical emittance at the quantum limit and results achieved.

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TUPRO050

Measurements of the Optical Functions at FLASH

optics, quadrupole, linac, controls

1141

J. Zemella, T. Hellert, M. Scholz, M. Vogt
DESY, Hamburg, Germany

In 2013 the superconducting soft x-ray Free Electron Laser FLASH at DESY (Hamburg, Germany) the extraction section needed to connect the 2nd beam line FLASH2 was installed. In order to allow simultaneous operation of the two beam lines (FLASH1/2), the optical functions in the extraction area needed to be modified. During the recommissioning of FLASH we have optimized, measured and corrected the optical functions in the machine. We report on the the results and the methods.

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TUPRO052

Study a ‘Sum’ Linear Coupling Resonance for J-PARC Main Ring: Observations and Simulations

resonance, operation, injection, emittance

1147

A.Y. Molodozhentsev, S. Igarashi
KEK, Ibaraki, Japan
Y. Sato, J. Takano
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

J-PARC Main Ring should deliver a high-power proton beam to neutrino experiments with limited particle losses. To meet this requirement low-order machine resonances have to be compensated. The linear coupling resonance Qx+Qy=43 has been identified as the potential source for significant particle losses at the collimator. The resonance compensation scheme has been studied experimentally by using a low intensity beam. To understand this process the simulations have been performed by using the PTC-ORBIT code. The Main Ring model has been developed to reproduce the machine operation including the initial stage of the acceleration. The 6D beam model has been defined to represent the ‘pencil’ beam used for this study. In frame of this report the single and multi particle dynamics will be discussed to understand the results of measurements, performed during RUN44 (November 2012). The results of the long-term tracking for this case will be presented. The obtained results can be used to benchmark the computer modeling the ‘sum’ linear coupling resonance with the experimental results.

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TUPRO057

Solenoid Siberian Snake Without Compensation of Betatron Oscillation Coupling in Nuclotron@JINR

solenoid, betatron, lattice, focusing

1162

Y. Filatov, V.A. Mikhaylov
JINR, Dubna, Russia
A.V. Butenko, A.D. Kovalenko
JINR/VBLHEP, Moscow, Russia
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

The influence of solenoids on spin is very efficient, but beam focusing is determined mainly by structural quadru-poles. The condition of stable orbital motion of particles does not require compensation of the betatron oscillation coupling. To reduce the influence of the Snake on orbital motion it is desirable to exclude compensating quads completely. The design of solenoid Siberian snake for the Nuclotron lattice is presented. The orbital functions of the lattice were calculated and the results are discussed.

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TUPRO075

Initial Analysis of the 4D Transfer Map in the Emma Non-Scaling Fixed Field Alternating Gradient Accelerator

simulation, betatron, quadrupole, alignment

1214

C.S. Edmonds, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
B.D. Muratori, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: STFC
The EMMA non-scaling Fixed Field Alternating Gradient accelerator (ns FFAG) is a ring consisting of 42 quadrupole pairs. The dipole fields which guide particles around the ring are arrived at through offsetting the quadrupoles from a reference axis. In the ideal case, first order 4D transfer maps will describe the turn by turn progression of a particle bunch in transverse phase space. This contribution sees the use of experimental data to calculate the 4D transfer map for EMMA at several different momenta, and a comparison made with maps produced through simulation.

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TUPME011

The Status of the Construction of MICE Step IV

solenoid, experiment, emittance, cavity

1364

P. Snopok
IIT, Chicago, Illinois, USA
E. Overton
Sheffield University, Sheffield, United Kingdom

Funding: DOE, NSF, STFC, INFN, CHIPP and several others
The International Muon Ionization Cooling Experiment will provide the demonstration ionization cooling. The experiment is being built in a series of Steps. Step IV, which consists of a tracking spectrometer upstream and downstream of an absorber/focus-coil (AFC) module will be completed in early in 2015. In this configuration, the emittance of the muon beam upstream and downstream of the absorber will be measured precisely allowing the emittance reduction and the factors that determine the ionization cooling effect to be studied in detail. The AFC module is a 22 liter volume of liquid hydrogen placed inside a superconducting focusing coil. The properties of lithium hydride, and possibly other absorber materials, will also be studied. All the components of Step IV have been manufactured and integration of the experiment in the MICE Hall at the Rutherford Appleton Laboratory is underway. A full study of ionization cooling will be carried out with Step V, which will include a short 201 MHz linac module in which beam transport is achieved with a superconducting “coupling coil”. The status of the preparation of the components of Step V of the experiment will be described briefly.

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TUPME025

Progress on Low Emittance Tuning for the CLIC Damping Rings

quadrupole, emittance, sextupole, dipole

1404

J. Alabau-Gonzalvo, H. Bartosik, Y. Papaphilippou
CERN, Geneva, Switzerland

In the frame of the CLIC main Damping Ring a study on the sensitivity of the lattice to different sources of misalignment is presented. The minimum equilibrium emittance is simulated and analytically estimated under dipole and quadrupole rolls, and quadrupole and sextupole vertical offsets. The result of this study establishes alignment tolerances to preserve the vertical emittance below the design value (1 pm·rad). Non-linear dynamics studies have been done to determine the dynamic aperture in the presence of misalignments.

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TUPME038

Wakefield excitation via a metasurface-loaded waveguide

impedance, wakefield, simulation, radiation

1437

E. Sharples
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
R. Letizia
Lancaster University, Lancaster, United Kingdom

Funding: Work supported by STFC Quota Studentship grant ST/K520133/1
A metallic waveguide loaded with layers of complementary split ring resonator (CSRR) based metasurface is presented for accelerator and coherent source applications. This structure presents left handed behaviour arising from the strong electrical response of CSRRs which form the metasurface and the transverse field confined between the closely positioned metasurface layers. The loaded waveguide structure is known to have a TM-like mode at 5.47GHz suitable for acceleration. In this paper, the results of wakefield simulations are presented and a narrow band excitation identified around the frequency of the TM-like mode, indicating strong coupling between the beam and the field of this mode.

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TUPME053

Study of the Energy Modulated Electron Cyclotron Resonance Ion Source for the Coupled RFQ-SFRFQ Cavity

ion, ion-source, cavity, ECR

1486

W.L. Xia, J.E. Chen, S.L. Gao, Z.Y. Guo, Y.R. Lu, S.X. Peng, Z. Wang, X.Q. Yan, J. Zhao, K. Zhu
PKU, Beijing, People's Republic of China

The coupled RFQ and SFRFQ cavity has been manufactured and tested recently. According to the beam dynamic design, the input He⁺ beam within 120° phase width is designed for the cavity to achieve over 98% transmission efficiency. An energy modulated electron cyclotron resonance (ECR) ion source was proposed and simulated. To achieve the 1% energy modulation on the 30keV direct current (DC) beam, two simplified RF power feeding structures for beam bunching were studied. The simulations show positive results as well as the bunched beam is achieved by the energy modulated ECR ion source.

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TUPRI025

Interplay of Touschek Scattering, Intrabeam Scattering, and RF Cavities in Ultralow-emittance Storage Rings

emittance, lattice, storage-ring, scattering

1612

S.C. Leemann
MAX-lab, Lund, Sweden

When it goes into operation in 2016, the MAX IV 3 GeV storage ring will be the first ultralow-emittance storage ring based on a multibend achromat lattice. These lattices make use of a large number of weak bending magnets which considerably reduces the amount of power radiated in the dipoles in comparison to power radiated from insertion devices. Therefore parameters such as emittance, energy spread, and radiated power are no longer constant during a typical user shift. Since the charge per bunch is usually high, intrabeam scattering (IBS) becomes very strong creating a dependence of emittance on stored current. Since the bunch length can vary as insertion device gaps change, the emittance blow-up from IBS is not constant either. Therefore, the emittance, bunch length, and hence the resulting Touschek lifetime have to be calculated in a self-consistent fashion taking into account the bare lattice, RF cavity settings, bunch charge, and gap settings. This paper demonstrates the intricate interplay between transverse emittance (insertion devices, emittance coupling), longitudinal emittance (tuning of main cavities as well as harmonic Landau cavities), and choice of stored current.

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TUPRI030

Beam Coupling Impedance of the New Beam Screen of the LHC Injection Kicker Magnets

impedance, kicker, injection, operation

1627

H.A. Day, M.J. Barnes, F. Caspers, E. Métral, B. Salvant, J.A. Uythoven
CERN, Geneva, Switzerland

The LHC injection kicker magnets experienced significant beam induced heating of the ferrite yoke, with high intensity beam circulating for many hours, during operation of the LHC in 2011 and 2012. The causes of this beam coupling impedance were studied in depth and an improved beam screen implemented to reduce the impedance. Results of measurements and simulations of the new beam screen design are presented in this paper: these are used to predict power loss and temperature of the ferrite yoke for operation after long shutdown 1 and for proposed HL-LHC operational parameters.

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TUPRI045

Beam Coupling Impedance Simulation in the Frequency Domain for the SIS100 Synchrotron

impedance, space-charge, dipole, synchrotron

1665

U. Niedermayer, O. Boine-Frankenheim
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim
GSI, Darmstadt, Germany

For the quantification of intensity thresholds due to coherent instabilities and beam induced heating in the FAIR synchrotron SIS100 a detailed knowledge of transverse and longitudinal beam coupling impedance is required. Due to the rather long proton and heavy-ion bunches, the relevant spectrum is below 100MHz. For the computation of beam coupling impedances in the low frequency regime, frequency domain methods are more advantageous than (explicit) time domain methods. We show the setup of a 2D finite element code that allows to compute the impedance for arbitrary longituninally homogeneous beam and structure shapes. Perfectly conducting pipes, a dispersive ferrite tube, and thin resistive beam pipe serve as test cases. The influence of the beam velocity on the coupling impedance is studied.

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TUPRI047

Electromagnetic Modeling of Open Cell Conductive Foams for High Synchrotron Radiation Rings

impedance, synchrotron, synchrotron-radiation, radiation

1671

S. Petracca, A. Stabile
U. Sannio, Benevento, Italy
A. Stabile
INFN-Salerno, Baronissi, Salerno, Italy

Open cell conductive foams (OCMF) have been recently suggested as an alternative to perforated metal patches for efficiently handling gas desorption from the beam pipe wall due to intense synchrotron radiation, yielding superior performance in terms of residual gas concentration and beam shielding. Experimental work is ongoing to assess their properties, including secondary emission yields and beam coupling impedances. In this communication we attempt a review of the Literature about electromagnetic modeling of OCMF, and outline a general framework for computing the surface impedance of OCMF walls and deriving the longitudinal and transverse beam coupling impedances thereof, based on effective medium theory and electromagnetic reciprocity. A critical analysis of the relevant modeling approximations is included.

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TUPRI054

FEM Analysis of Beam-coupling Impedance and RF Contacts Criticality on the LHC UA9 Piezo Goniometer

impedance, simulation, resonance, experiment

1692

A. Danisi, R. Losito, A. Masi, A. Passarelli, B. Salvant, C. Zannini
CERN, Geneva, Switzerland

The UA9 piezo-goniometer has been designed to guarantee micro-radians-accuracy angular positioning of a silicon crystal for a crystal collimation experiment in the LHC, and to minimize the impact on the LHC beam-coupling impedance. This paper presents a Finite Element Method (FEM) study of the device, in both parking and operational positions, to evaluate its impact on the LHC impedance budget. The study has been a progressive simulation work, started from the simplification of the original detailed design, and aimed at highlighting the effect of single details (e.g. objects in confining chambers) on the longitudinal and transverse components of beam-coupling impedance. In addition, the shielding contribution of the RF gaskets has been carefully evaluated, with the objective to assess the consequences for operation in case of their failure. Sensitivity analyses to simulation parameters are also performed, in order to test the FEM model robustness. A final word is drawn on the overall device impedance criticality.

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TUPRI055

Theoretical Analysis of Metamaterial Insertions for Resistive-wall Beam-coupling Impedance Reduction

impedance, insertion, vacuum, interface

1695

A. Danisi, R. Losito, A. Masi, B. Salvant, C. Zannini
CERN, Geneva, Switzerland

Resistive-wall impedance usually constitutes a significant percentage of the total beam-coupling impedance budget of many accelerator structures (e.g. for LHC, it can be more than 50%). Reduction techniques for resistive-wall components entail high electrical-conductivity coatings. This paper proposes the use of metamaterials, having negative values of magnetic permeability or dielectric permittivity (or both), for sensibly reducing or theoretically nearly cancelling the resistive-wall component of beam-coupling impedance. The proposed approach is developed by means of an equivalent transmission-line model, whose results show the potential reduction of both longitudinal and transverse impedance when using metamaterial insertions. The effects on the real and imaginary part have been singled out. The effectiveness of such materials is discussed both for negative-permittivity and for negative-permeability cases, which actually show different impacts and can be then target of proper engineering. This first-stage study opens the possibility of considering metamaterials for impedance mitigation or for setting up proper experimental setups.

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TUPRI061

Power Loss Calculation in Separated and Common Beam Chambers of the LHC

impedance, electron, simulation, cryogenics

1711

C. Zannini, G. Iadarola, G. Rumolo
CERN, Geneva, Switzerland
G. Iadarola
Naples University Federico II, Science and Technology Pole, Napoli, Italy

The performance of 25 ns beams in the LHC is strongly limited by the electron cloud. To determine the amount electron cloud in the cold sections of the machine, it is very important to be able to disentangle the beam induced heating due to the beam coupling impedance from that attributable to electron cloud. This paper will focus on the calculation of the first contribution. First, the impedance model used for the calculation of the beam induced power loss is briefly discussed. Then, the methods for the calculation of the beam induced power loss in regions with one or two beams are also described. Finally, the calculated power loss is compared with the measured heat loads for both 25 and 50 ns beams in both the LHC arcs and in the inner triplets (ITs).

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TUPRI062

The Mode Matching Technique Applied to the Transverse Beam Coupling Impedance Calculation of Azimuthally Symmetric Devices of Finite Length

impedance, cavity, simulation, vacuum

1714

N. Biancacci, E. Métral, B. Salvant, C. Zannini
CERN, Geneva, Switzerland
M. Migliorati, L. Palumbo
URLS, Rome, Italy
V.G. Vaccaro
Naples University Federico II and INFN, Napoli, Italy

The infinite length approximation is often used to simplify the calculation of the beam coupling impedance of accelerator elements. This is expected to be a reasonable assumption for devices whose length is greater than the transverse dimension but may be a less accurate approximation for segmented devices. In this contribution we present the extension of the study of the beam coupling impedance of a finite length device to the transverse plane. In order to take into account the finite length, we decompose the fields in the cavity and in the beam pipe into a set of orthonormal modes and apply the Mode Matching method to obtain the impedance. To validate our method, we will present comparisons between analytical formulas and 3D electromagnetic CST simulations.

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TUPRI063

Electromagnetic Simulations for Non-ultrarelativistic Beams and Application to the CERN Low Energy Machines

impedance, simulation, space-charge, vacuum

1718

C. Zannini, N. Biancacci, T.L. Rijoff, G. Rumolo
CERN, Geneva, Switzerland
T.L. Rijoff
TU Darmstadt, Darmstadt, Germany

In the framework of the PS-Booster upgrade project an accurate impedance model is needed in order to determine the effect on the beam stability and assess the impact of the new devices to be installed in the machine. CST 3-D EM simulations are widely used to estimate the impedance contribution of the different devices along the CERN accelerator complex. Unlike the highly relativistic case, in which the reliability of the EM solver has been proved in many specific cases by comparing simulations with analytical results, the nonrelativistic case has been so far not yet benchmarked. In order to use systematically CST 3-D EM simulations for the PS-Booster, or even lower energy machines like the antiproton decelerator ELENA, a validation campaign has been carried out. The main complication to single out the beam coupling impedance, as resulting from the interaction of the beam with the surroundings, consisted of removing reliably the strong contribution of the direct space charge of the source bunch, which is included in the EM calculation. The simulation results were then benchmarked with the analytical results for the case of a PEC cylindrical tube and of a ferrite loaded kicker.

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TUPRI087

A Wideband Slotted Kicker Design for SPS Transverse Intra-bunch Feedback

kicker, impedance, feedback, interface

1772

J.M. Cesaratto, J.D. Fox, C.H. Rivetta
SLAC, Menlo Park, California, USA
D. Alesini, A. Gallo, M. Zobov
INFN/LNF, Frascati (Roma), Italy
S. De Santis
LBNL, Berkeley, California, USA
W. Höfle
CERN, Geneva, Switzerland

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP) and by the EU FP7 HiLumi LHC - Grant Agreement 284404.
In order for the SPS to meet the beam intensity demands for the HL-LHC upgrade, control and mitigation of transverse beam instabilities caused by electron cloud and TMCI will be essential. For this purpose a wideband intra-bunch feedback method has been proposed, based on a 4 GS/s front end data acquisition and processing, and on a back end frequency response extending to at least 1 GHz. A slotted type kicker, similar to those used for stochastic cooling, as well as an array of stripline kickers have been considered as the terminal elements of the feedback system. A slotted TEM type kicker has been designed fulfilling the bandwidth and kick strength requirements for the SPS application. In this paper we present an updated version of the design and electromagnetic characteristics, leading into the mechanical design and construction of the kicker occurring later this year.

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TUPRI104

A Beam Arrival Time Cavity for REGAE at DESY

cavity, electron, gun, operation

1820

M. Hansli, A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
K. Flöttmann, D. Lipka, H. Schlarb, S. Vilcins
DESY, Hamburg, Germany
F.J. Grüner, B. Zeitler
CFEL, Hamburg, Germany

Funding: Kindly funded by BMBF within FSP302.
REGAE (Relativistic Electron Gun for Atomic Exploration) at DESY in Hamburg is a linear accelerator for electron diffraction experiments. It is upgraded to allow for laser driven wake field accelerator experiments. The bunch length is around 10 fs and the wakefield structure is about 100 fs and the synchronization of the laser and the electron bunch needs to be in order of the bunch length. To achieve this, a RFbased scheme will be used, comparing the phase of a beam induced signal with the reference clock. To improve the performance for the operation with charges well below 1 pC a beam arrival time cavity (BAC) at 3.025 GHz is foreseen as a highly sensitive pickup. To provide the maximum energy to the measurement electronics, the cavity needs a high R=Qvalue and an optimized coupling. An over-coupled setting might be beneficial as it provides a higher signal-to-noise ratio for the first samples. In this paper the concept of the beam arrival time cavity, the influence of the dark current on the measurement and parameter studies and optimization of the cavity itself are presented.

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WEOCA03

DAΦNE Operation with the Upgraded KLOE-2 Detector

luminosity, detector, operation, collider

1883

C. Milardi, D. Alesini, M.E. Biagini, M. Boscolo, B. Buonomo, S. Cantarella, A. De Santis, G.O. Delle Monache, G. Di Pirro, A. Drago, L.G. Foggetta, O. Frasciello, A. Gallo, A. Ghigo, F. Guatieri, S. Guiducci, F. Iungo, C. Ligi, G. Mazzitelli, L. Pellegrino, R. Ricci, U. Rotundo, C. Sanelli, G. Sensolini, M. Serio, A. Stecchi, A. Stella, M. Zobov
INFN/LNF, Frascati (Roma), Italy
R. Gargana, A. Michelotti
Consorzio Laboratorio Nicola Cabibbo, Frascati, Italy
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia
M. Tobiyama
KEK, Ibaraki, Japan
A. Valishev
Fermilab, Batavia, Illinois, USA

The DAΦNE collider has been successfully commissioned after the experimental detector modification and a major upgrade and consolidation program involving a large part of the accelerator complex. This paper presents the Φ-Factory setup and the achieved performances in terms of beam currents, luminosity, detector background and related aspects.

Slides WEOCA03 [2.424 MB]

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WEPRO016

Injection/Extraction Kicker for the ALS-U Project

kicker, impedance, injection, extraction

1977

S. De Santis, W. Barry, S. Kwiatkowski, T.H. Luo, G.C. Pappas, L.R. Reginato, D. Robin, C. Steier, C. Sun, H. Tarawneh, W.L. Waldron
LBNL, Berkeley, California, USA

Funding: Work supported by the US Department of Energy under Contract no. DEAC02-05CH11231
The ALS-II proposal consists in the upgrade of the existing Advanced Light Source at LBNL to a new ultra-low emittance lattice for production of diffraction-limited soft x-rays. In order to compensate for the reduced beam lifetime we intend to operate the machine in continuous top-off mode, where one of several bunch trains is extracted every 30-60 seconds and swapped with a fresh train from the accumulator ring, which is injected on axis without perturbing the circulating beam. In this paper we present a possible design for the injection/extraction kicker based on matched stripline electrodes. The main parameters of such a kicker are discussed in reference to the minimum gap between trains, the storage ring lattice, and the characteristics of a suitable pulser. We also present results from 3D electromagnetic modeling of the proposed kicker performed to evaluate its rise and fall time and field uniformity characteristics.

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WEPRO066

Study for Space Charge effect in tune space at J-PARC MR

resonance, space-charge, quadrupole, simulation

2100

K. Ohmi, S. Igarashi
KEK, Ibaraki, Japan
H. Harada
JAEA, Ibaraki-ken, Japan
Y. Sato
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Choice of tune operating point is serious for operation of high intensity proton machine. Space charge force induces tune spread and nonlinear resonance. Nonlinear resonances are also contained in accelerator lattice. We discuss optimization of operating point based on space charge simulation in J-PARC Main Ring.

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WEPRO097

The Base Parameters of the Compact 27 GHz Electron Linac for Medical Application

electron, linac, simulation, injection

2189

S.M. Polozov, T.V. Bondarenko, Yu.D. Kliuchevskaia, V.I. Rashchikov
MEPhI, Moscow, Russia

A compact and light-weight electron linac is attractive for a number of medical applications including intra-operational and cyber-knife systems. The design of such an accelerator can nowadays be based on using of a powerful high-voltage high-frequency gyrotron which can provide now in pulsed regime a peak power up to 15 MW at the frequency about of 30 GHz. Taking into account this possibility, the paper presents the results of design and numerical simulations for the electron beam dynamics in a linac with the operating frequency of 27 GHz. Designed linac consists of two parts: gentle buncher and main accelerating section. The beam bunching is complicated at 1 cm wavelength because high energy about 2 MeV is necessary for beam injection into the main stage with v/c=1. Beam dynamics simulations are held using BEAMDULAC-BL code*. The electrodynamics of accelerating structure based on biperiodic structure is presented. The electron gun simulation is also discussed. The RF feeding is planned to be realized using a gyrotron to be designed in IAP RAS. The gyrotron is capable to produce 2 MW peak RF power in pulses with pulse duration 400 μs and repetition rate 10 Hz.
T.V. Bondarenko, E.S. Masunov, S.M. Polozov. BEAMDULAC-BL code for 3D simulation of electron beam dynamics taking into account beam loading and coulomb field. PAST, 2014 (in press).

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WEPRO110

Power Plant Based on Subcritical Reactor and Proton LINAC

neutron, target, proton, booster

2224

A.G. Golovkina, I.V. Kudinovich, D.A. Ovsyannikov
St. Petersburg State University, St. Petersburg, Russia
A.A. Bogdanov
KSRC, St. Petersburg, Russia

Nuclear power plant based on accelerator driven subcritical reactor (ADSR) is considered. Such systems demonstrate higher safety because the fission proceeds in subcritical core and necessary neutron flux is reached with external neutrons generated in target of heavy nuclides. In order to efficiently use ADSR for energy production, it’s needed the total power, generated in the reactor, to be greater than power inputs for charged particles acceleration. The plant driven by middle-energy accelerator, which is cheaper than high-energy accelerators, proposed for these purposes, is considered. So it’s necessary to find other ways to amplify reactor power outputs. Thus, the technical solution to increase power gain of small-sized power plant with a linear proton accelerator (energy 300-400 MeV, average current 5 mA) is proposed. Thermal power up to 300 MW was reached.

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WEPME007

Multi-Bunch Generator Cavity

cavity, impedance, electron, cathode

2267

E.A. Savin, S.V. Matsievskiy, Ya.V. Shashkov, N.P. Sobenin
MEPhI, Moscow, Russia
A.A. Zavadtsev
Nano, Moscow, Russia

The concept of the six bunch generator cell for the washers and diaphragm loaded structure (Moscow Meson Factory) power supply is proposed. The required power is 0.8 MW on the 991 MHz frequency. The high-voltage electron gun produces electron bunches and puts them into the cylindrical resonator tuned to TE02 mode and operating frequency. Bunches produces RF field that takes energy from the following bunches and then energy transfer to the accelerating structure throw the tuned coupling system.

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WEPME068

Mitigating Noise Sources in MTCA.4 Electronics for High Precision Measurements

instrumentation, distributed, FPGA, simulation

2436

U. Mavrič, M. Hoffmann, F. Ludwig, H. Schlarb
DESY, Hamburg, Germany

The RF field detection instrumentation plays a crucial role in modern accelerator performance. The most critical section is the transition from the analog signal processing to the digitalization. In this paper we present state of the art performance of COTS components and limitations imposed by crate-oriented solutions. We give recipes on how to optimize performance and present some of the recent results.

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WEPRI006

High Power RF Input Couplers and Test Stand for the BERLinPro Project

cavity, booster, SRF, linac

2487

V.F. Khan, W. Anders, A. Burrill, J. Knobloch, A. Neumann
HZB, Berlin, Germany

Funding: Work supported by German Federal Ministry of Education and Research, Land Berlin, and grants of the Helmholtz Association
The BERLinPro project, under construction at HZB, is a 100 mA, 50 MeV superconducting RF (SRF) energy recovery linac (ERL) being built to study the accelerator physics of operating a high current SRF ERL. For this high current operation, coaxial RF power couplers capable of handling 130 kW of power, c.w. at 1.3 GHz are required for both the SRF gun and booster cavities. In order to achieve this power level a coupler has been designed based on the high power coupler currently in use at the KEK-cERL. A key improvement that was made to the coupler was the modification of the coupler tip, termed a golf-tee. This modification is incorporated so as to achieve the desired coupling, Qext ~10⁵, with minimal coupler penetration into the beampipe. Herein, we discuss the RF design and properties of the high-power coaxial coupler for the gun as well as booster cavity of BERLinPro, along with the design of the test stand for conditioning a pair of couplers.

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WEPRI007

Booster Cavity and Fundamental Power Coupler Design Issues for BERLinPro

cavity, booster, SRF, emittance

2490

A. Neumann, M. Abo-Bakr, W. Anders, A. Burrill, V.F. Khan, J. Knobloch, S. Wesch
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
HZB has started building the 50MeV, 100mA demonstrator energy-recovery-linac (ERL) facility BERLinPro. The high power injector system needs to deliver this beam at 6.5MeV by combining the energy gain of a 1.4 cell SRF photo-injector and three Cornell style 2-cell booster cavities. One booster cavity will be operated at zero-crossing for bunch energy chirping. Thus two booster cavities have to deliver 2MV each requiring a strong coupling with a loaded Q of 10⁵. To house the two envisaged KEK fundamental power couplers (FPC) with the cavity, the geometry was slightly modified. Further, to increase coupling and reduce transverse kick effects to the beam, a ”golf-tee” antenna tip was designed. This paper summarizes the SRF challenges for the booster cavities, the operational conditions and the modification to the KEK couplers, including tracking calculations to estimate the coupler kick effect to higher order.

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WEPRI008

First Cavity Design Studies for the BESSY-VSR Upgrade Proposal

cavity, HOM, damping, impedance

2493

A. Neumann, A. Burrill, P. Goslawski, A. Jankowiak, J. Knobloch, M. Ries, M. Ruprecht, A.V. Vélez, G. Wüstefeld
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung and Land Berlin
Recently HZB proposed an upgrade of the 3rd generation synchrotron light source BESSY II allowing simultanous long and short pulse operation*. For this scheme to work superconducting higher harmonic cavities of the fundamental 500 MHz at two frequencies need to be installed in the BESSY II storage ring. Given an appropiate choice of the higher harmonics the resulting gradient leads to a beating effect of the effective longitudinal focussing voltage at the stable fix points resulting in different bunch lengths in subsequent buckets. This project places stringent requirements on the cavity performance, as high accelerating fields, excellent HOM damping capabilities and high reliability as they will operate in a 300 mA 24/7 user facility. In this paper we describe the requirements for the cavity design and first designs steps.
* G. Wüstefeldt et al., Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proc. of IPAC'11, San Sebástian, Spain

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WEPRI009

Parameter Studies and Geometry Optimization on Superconducting Multicell RF Cavity Resonators

factory, cavity, HOM, RF-structure

2496

B.D. Isbarn, B. Riemann, M. Sommer, T. Weis
DELTA, Dortmund, Germany

Funding: Work partly supported by the BMBF under contract No. 05K13PEB
Modern accelerator concepts for high intensity electron beams often require superconducting multicell RF-cavity-resonators in circular accelerators (e.g. storage rings). Caused by strong beam-cavity interaction and due to high quality factors of superconducting RF-structures special care of lower order (LOM) and higher order (HOM) modes must be taken. Various numerical studies were performed to numerically calculate the dependence of different figures of merit (e.g. external quality factors Qext) with respect to the geometry parameters and cell number of the RF-structure, focused on the propagation and damping of low and higher order modes. To ease the numerical effort an optimization routine has been developed which automatically optimizes the geometry based on goal functions. In this context it turned out that cell geometries defined by spline functions have advantages compared to the standard elliptical parametrization regularly used. The number of free parameters is substantially reduced which facilitates the search for optimum solutions.

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WEPRI016

Status of the Vertical Testing of the XFEL Third Harmonic Cavity Series

cavity, HOM, linac, operation

2508

J.F. Chen, M. Bertucci, A. Bosotti, M. Fusetti, C. Maiano, P. Michelato, L. Monaco, M. Moretti, C. Pagani, R. Paparella, P. Pierini, D. Sertore
INFN/LASA, Segrate (MI), Italy

The prototype cavities of the XFEL 3rd harmonic system at the XFEL injector have been tested vertically before their final integration into the He tank. The Vertical Test facility has been upgraded in preparation of the series and the results so far obtained are presented.

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WEPRI040

On the Optimal Design of Elliptical Superconducting Cavities

cavity, simulation, diagnostics, target

2565

G. Costanza
Lund University, Lund, Sweden

In this paper a linear regression analysis is used to analyze the behavior of the inner cell of an elliptical cavity. The aim is to understand how the RF parameters are correlated to each other and how they are affected by the change of the geometric parameters. This is done by fitting the RF data to a linear model. The data is obtained by simulating a set of different inner cells automatically by the use of a script. The results are useful in several ways: first of all the analysis sheds light on the behavior of elliptical cavities, in particular on its limitations. The analysis is carried out in the framework of optimal design so it is useful for the cavity designer since it allows to choose the geometry at an early stage of the design. It is also possible to make predictions on the performance of the cavity which are in very good agreement with the simulations. Such predictions facilitate the design of the accelerator when choosing the type and number of cavities and when writing the specifications for the cavities to be used in the accelerator.

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WEPRI049

Optimization of Window Position on Diamond SCRF Cavities

cavity, operation, simulation, impedance

2592

S.A. Pande, C. Christou
DLS, Oxfordshire, United Kingdom

The Diamond storage ring uses CESR type superconducting cavities. These cavities have a fixed coupling resulting in fixed Qext which is considerably higher than the optimum. We use 3 stub tuners to match the cavities under these non-optimum conditions. Diamond Cavity-1 will soon be refurbished. This opportunity could be used to lower the Qext on the cavity. One of the options is to modify the coupling tongue geometry along with a matching section. This may require cutting off the beam tube with the coupler for rework or it may need to be newly fabricated. We investigated another option to lower the Qext of the cavity by optimising the location of the window with respect to the cavity, maintaining the same coupling tongue geometry. The height of the waveguide on the vacuum side of the window differs from that of the coupling waveguide on the cavity resulting in a step. The location of window with respect to the cavity makes a significant difference to the ultimate Qext obtained after putting the window in place. In this paper we present the results of our numerical simulations comparing the present and the proposed window position under different operating conditions.

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WEPRI053

Phase Method of Measuring Cavity Quality Factor

cavity, simulation, resonance, data-analysis

2604

O.S. Melnychuk, R.V. Pilipenko, Y.M. Pischalnikov, W. Schappert, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA

Novel method for measuring intrinsic quality factor of superconducting RF (SRF) cavities using both amplitude and phase information of forward, reflected, and transmitted cavity signal is discussed. Advantages of the method in comparison with traditional types of cavity quality factor measurements are highlighted. Computer simulations and evaluation of uncertainties for the measurements are described. Analysis of data collected at vertical test facility for SRF cavities at Fermilab is presented.

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WEPRI057

RF Control and DAQ Systems for the Upgraded Vertical Test Facility at Fermilab

cavity, controls, interface, instrumentation

2612

Y.M. Pischalnikov, R.H. Carcagno, F.L. Lewis, R. Nehring, R.V. Pilipenko, W. Schappert
Fermilab, Batavia, Illinois, USA

Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
The Fermilab Vertical Cavity Test Facility (VCTF) [1] is a used to test production cavities prior to their installation in cryomodules and to characterize the performance of research cavities as part of the extensive SRF cavity R&D program at FNAL. The performance of a variety of SRF cavities (325MHz, 650MHz, 1300MHz; bare and dressed) can be measured at VCTF. Recently FNAL upgraded the facility by adding two additional test stands (VTS2&3) in preparation for production of cavities for two new linear accelerators (LCLS II and PIP II). This paper provides an overview of the design features, technical parameters and experience with first operation of the upgraded RF control and DAQ systems.

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WEPRI065

SRF Material Performance Studies using a Sample Host Cavity

cavity, niobium, SRF, controls

2638

D.L. Hall, D. Gonnella, M. Liepe, I.S. Madjarov
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

A sample-host TE-mode cavity developed at Cornell for the purposes of studying novel superconducting materials has undergone further testing using a niobium sample plate. In initial testing the peak field achieved on the sample plate was (45 ± 4.5) mT, although this was limited by the amount of input power available. New tests have been performed using both an improved RF power system and a temperature mapping system for precision measurements of surface resistance as a function of location on the sample plate. Results of the most recent test, in which the cavity achieved a peak sample plate field of (81 ± 4) mT using a high-RRR niobium sample plate, are presented and future work on the cavity is discussed.

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WEPRI068

Conceptual Design of an Ideal Variable Coupler for Superconducting Radiofrequency 1.3 GHz Cavities

cavity, vacuum, scattering, Windows

2648

C. Xu, S.G. Tantawi
SLAC, Menlo Park, California, USA

We present a new type of fundamental mode accelerator structure coupler. This coupler has a very simplified mechanical structure and is equipped with a novel vacuum window structure that allows the coupler to be divided into two parts. These two parts are fully thermally isolated, only coupled by thermal radiation. The rf power on the other hand get coupled perfectly from one part to the other. This is truly novel approach which is quite different than the conventional approach to this problem such as chock structure. The structure in general is slightly overmoded. We show that this structure can also be adopted to change the coupling coefficient and thus be tuned for an external Q. This could be of great utility for CW operation. We show the analytical and numerical calculation for a two window variable coupler.

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WEPRI078

Development of a Quarter-wave Coaxial Coupler for 1.3 GHz Superconducting Cavities

cavity, niobium, HOM, SRF

2675

Y. Xie, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Superconducting ILC-type cavities have an rf coupler that is welded on. A detachable coupler will reduce conditioning time (can be conditioned separately), reduce cost and improve reliability. The problem with placing an extra flange in the superconducting cavity is creating a possible quench spot. Euclid Techlabs LLC designed a coupler and optimized its geometry that yielding an area on the surface with zero magnetic field (hence zero surface current). By placing a flange in that area we are able to avoid disturbing surface currents that typically lead to a quench. The coupler is optimized to preserve the axial symmetry of the cavity and rf field. The rf test results of this type coupler with a 1.3 GHz ILC-type single-cell cavity at Fermilab will be reported and discussed.

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THOBA02

Status of the Emittance Transfer Experiment Emtex

emittance, solenoid, quadrupole, injection

2798

M.T. Maier, L. Groening, C. Mühle, I. Pschorn, P. Rottländer, C. Will, C. Xiao
GSI, Darmstadt, Germany
M. Chung
Fermilab, Batavia, Illinois, USA

In order to improve the injection efficiency of the round UNILAC heavy ion beam into the asymmetric acceptance of the SIS18 it would be of great advantage to decrease the horizontal emittance by a so called emittance transfer to the vertical plane. In this contribution the present status of the emittance transfer experiment EMTEX at GSI will be reported. A short introduction about the theoretical background of the technique will be given, while the main part is dedicated to the practical solutions setting up a test beam line at GSI. Finally, the results of a first commissioning beam time will be presented. The scheduled beam time to apply the emittance transfer technique foreseen in spring 2014 had to be shifted to calendar week 26 in 2014, just after this conference, as some components have not been delivered in time by the contractor. The results and comparison to the theoretical predictions you may find in later publications.

Slides THOBA02 [1.928 MB]

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THPRO079

Quantitative Analysis of Trapping Probability for Quasi-integrable Two-degree of Freedom Maps

resonance, simulation, extraction, synchrotron

3065

M. Giovannozzi, C. Hernalsteens, J. Williams
CERN, Geneva, Switzerland
A. Bazzani
Bologna University, Bologna, Italy
C. Hernalsteens
EPFL, Lausanne, Switzerland

A key ingredient for the Multi-Turn Extraction (MTE) at the CERN Proton Synchrotron is the beam trapping in stable islands of transverse phase space. In a previous paper a method allowing analytical estimation of the fraction of beam trapped into resonance islands as a function of the Hamiltonian parameters has been presented. Such a method applies to one-degree of freedom models of betatronic motion. In this paper, the analysis is extended to the more realistic and challenging case of two-degree of freedom systems, in which the interplay between the horizontal and vertical motion is fully included. Numerical simulations are presented and the results are discussed in detail.

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THPME011

First Coupled CH Power Cavity for the FAIR Proton Injector

cavity, linac, proton, alignment

3232

R. M. Brodhage, G. Clemente, W. Vinzenz
GSI, Darmstadt, Germany
R. M. Brodhage, U. Ratzinger
IAP, Frankfurt am Main, Germany

For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. The main acceleration of this room temperature linac will be provided by six CH cavities operated at 325 MHz. Each cavity will be powered by a 2.5 MW Klystron. For the second acceleration unit from 11.5 MeV to 24.2 MeV a 1:2 scaled model has been built. Low level RF measurements have been performed to determine the main parameters and to prove the concept of coupled CH cavities. In 2012, the assembly and tuning of the first power prototype was finished. Until then, the cavity was tested with a preliminary aluminum drift tube structure, which was used for precise frequency and field tuning. In 2013 the final drift tube structure has been welded inside the main tanks and the preparation for copper plating has taken place. This paper will report on the main tuning and commissioning steps towards that novel type of DTL and it will show the latest results measured on a fully operational CH proton cavity shortly before copper plating.

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THPME016

Experimental Results on SCDTL Structures for Protons

proton, beam-transport, DTL, rfq

3247

L. Picardi, A. Ampollini, G. Bazzano, P. Nenzi, C. Ronsivalle, V. Surrenti, M. Vadrucci
ENEA C.R. Frascati, Frascati (Roma), Italy
F. Ambrosini
URLS, Rome, Italy

The medium-energy section of the proton linear accelerator for radiotherapy under realization in the framework of the TOP-IMPLART Project consists in a high frequency 7-35 MeV SCDTL (Side Coupled Drift Tube Linac) structure. The structure, made of 4 modules supplied by one klystron, has been completely designed. The first module up to 11.6 MeV has been built and is under commissioning at ENEA-Frascati and the second and third modules are under realization. The paper describes the system and presents the main results of the experimental activity on this part of the accelerator.

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THPME017

Electromechanical Analysis of SCDTL Structures

cavity, proton, feedback, linac

3250

M. Ciambrella, F. Cardelli, M. Migliorati, A. Mostacci, L. Palumbo
URLS, Rome, Italy
L. Ficcadenti, V. Pettinacci
INFN-Roma, Roma, Italy
L. Picardi, C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

The Side Coupled Drift Tube Linac (SCDTL) is a 3 GHz accelerating structure for proton therapy linac designed for TOP-IMPLART, an Intensity Modulated Proton Linear Accelerator for Radio-Therapy. The structure is made up of short DTL accelerating tanks for low current proton beams, coupled by side coupling cavities. The purpose of this paper is to report on the analysis of electromagnetic and the thermo-mechanical behavior for the SCDTL structure. The 3D electromagnetic analysis is used to derive the power dissipation on the structure; then one can infer the temperature distribution and deformation field in order to eventually evaluate their feedback on the electromagnetic properties of the structure as, for instance, the cavity resonant frequency shift. Such a "multi-physics'' analysis has been performed for different supporting stem geometries in order to optimize the shunt impedance and the R/Q for SCDTL cavities.

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THPME018

Global Search Methods for Electromagnetic Optimization of Compact Linac Tanks

linac, proton, cavity, HOM

3253

O. Losito, V. Dimiccoli, G. Rutigliani
ITEL, Ruvo di Puglia, Italy
L. De Palma, F. Prudenzano
Politecnico di Bari (DEI), Bari, Italy

We shows the optimization of a five cell tank to be included as first multi-cavity within a LINAC section accelerating a proton beam from 7 MeV to higher energies, useful for proton therapy. The tank performance depends on a set of physical (beam characteristics) and geometrical parameters (radius and lengths of accelerating and coupling cavities, radius and thickness of the coupling holes among accelerating cells, the radius and the thickness of the coupling holes between off-axis coupling cells and accelerating ones). PSO (Particle Swarm Optimization) and ACO (Ant Colony Optimization) have been used as approaches for the electromagnetic optimization. The model used for the fitness calculation takes into account all the most important effects occurring in the tank coupled cavities loaded by the proton beam. The codes based on PSO and ACO have enabled the global and stochastic identification of about ten optimized parameters. The design goodness has been tested via Particle and Microwave CST Studio © simulation. The optimized tank accelerates the proton beam input energy from Ein=7 MeV to about Eout= 8.2 MeV. These values, well agree with other designs reported in literature.

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THPME055

RF Tuning of the IPHI RFQ

rfq, dipole, quadrupole, operation

3355

O. Piquet, M. Desmons, A. France
CEA/DSM/IRFU, France

The construction of IPHI (High Power Proton Accelerator) is in its final step of installation. The RFQ will accelerate beam up to 100 mA with energy up to 3 MeV. The RFQ, made of six modules, one meter each, is of the four-vane type. The RFQ is divided in 2-meter long segments with capacitive coupling. It is also equipped with 96 fixed tuners and four waveguide RF ports located in the fourth module. This paper describes the procedure used to tune the accelerating field and power couplers of the RFQ.

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THPME059

Preparation of the Coupled RFQ-IH-cavity for FRANZ

rfq, DTL, cavity, operation

3367

M. Heilmann, C. Claessens, O. Meusel, D. Mäder, U. Ratzinger, A. Schempp, M. Schwarz
IAP, Frankfurt am Main, Germany

The Frankfurt neutron source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra-short neutron pulses at high intensities and repetition rates. The neutrons will be produced using the 7Li(p, n)7Be reaction induced by a proton beam. The 175 MHz IH-type drift tube linac with 8 gaps succeeds a 4-rod-RFQ. Together they form a coupled linac combination with a length of 2.3 m and accelerate the protons from 120 keV to 2.03 MeV. As the RF losses add up to 200 kW, the cooling of both accelerators is a central challenge. The RFQ-IH combination is powered by a radio frequency amplifier, which couples the RF power into the RFQ. The two structures are connected via inductive coupling. The initial beam operation of the accelerators is configured for 50 mA in cw mode. The IH-components were fabricated, RF tuning measurements are underway. The RFQ and the IH-DTL will be conditioned separately and then be connected, aiming for a beam operation at the end of 2014. A main challenge in fabrication was the precise welding required for the water cooled drift tubes and stems.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME059

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THPME133

Bunch Length Measurement with 2-Cell RF-Deflector at Waseda University

electron, cavity, gun, cathode

3556

T. Takahashi, Y. Nishimura, M. Nishiyama, K. Sakaue, M. Washio
Waseda University, Tokyo, Japan
T. Takatomi, J. Urakawa
KEK, Ibaraki, Japan

We have been studying on a system to measure the length of electron bunch generated by a photocathode rf electron gun at Waseda University. We adopted the rf-deflector system which can convert the longitudinal distribution to transverse by sweeping the electron bunch. By using HFSS, we optimized the design of the 2 cell rf-deflector which is operating on π-mode, dipole (TM110-like) mode at 2856 MHz. The fabrication and the tuning of the rf deflector have successfully processed. We have installed the rf-deflector in the accelerator system of Waseda University, and performed the measurement of the bunch length. It is confirmed that this rf-deflector has the temporal resolution of 167fs with 700kW supply when the beam energy is 4.8MeV. This means that our rf-deflector system has possibility to measure the ultra-short bunch length. In this conference, the rf-deflector system in Waseda University, the result of the bunch length measurement, the performance of the rf-deflector and the future plan will be reported.
Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690 and the Quantum Beam Technology Program of MEXT.

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THPME163

Beam Size and Emittance Reconstruction in the RMTL of Future Linear Colliders

emittance, diagnostics, target, optics

3647

A. Faus-Golfe, J. Resta-López
IFIC, Valencia, Spain

Funding: Work supported by FPA2010-21456-C02-01
Precise and fast beam size measurement and emittance reconstruction in the different subsystems and transfer lines of the Future Linear Colliders (ILC and CLIC) will be essential for beam tuning in order to achieve the required luminosity. In this paper we investigate the feasibility of using a multi-Optical Transition Radiation (m-OTR) system for fast transverse beam size measurement, emittance reconstruction and coupling correction in the Ring to Main Linac (RTML) of the FLCs. Diagnostic sections of the RTML have been matched to the optimum optical conditions for emittance reconstruction. The necessary requirements for the OTR monitors to be placed in the RTML are discussed.

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THPRI030

Progress Towards Completion of the MICE Demonstration of Muon Ionization Cooling

emittance, cavity, solenoid, lattice

3831

D.M. Kaplan, P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA
A.J. Dobbs
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
P. Snopok
Fermilab, Batavia, Illinois, USA

Funding: DOE, NSF, STFC, INFN, CHIPP and several others
The Muon Ionization Cooling Experiment (MICE) at the Rutherford Appleton Laboratory aims to demonstrate ~10% ionization cooling of a muon beam, by its interaction with low-Z absorber materials followed by restoration of longitudinal momentum in RF linacs. MICE Step V will provide the flexibility for a thorough exploration and characterization of the performance of ionization cooling. Step V will include four RF cavities to provide 8 MV/m gradient in a strong magnetic field. This entails an RF drive system to deliver 2 MW, 1 ms pulses of 201 MHz frequency at 1 Hz repetition rate, the distribution network to deliver 1 MW to each cavity with correct RF phasing, diagnostics to determine the gradient and the muon transit phase, and development of the large diameter magnets required in order to keep the muons focused through the linacs. Progress towards the completion of Step V is described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI030

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THPRI035

Design and Simulation of Side Coupled Six MeV Linac for X-Ray Cargo Inspection

cavity, acceleration, simulation, electron

3844

S. Ahmadiannamin, F. AbbasiDavani, R. Ghaderi, F. Ghasemi
sbu, Tehran, Iran
M. Lamehi Rashti
IPM, Tehran, Iran
S. Zarei
Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran

Using in X-ray cargo inspection is one of most applications of linear accelerators. This paper represents design and simulation of Side Coupled Six MeV cavity. The electromagnetic simulation of structure was carried out in the SUPERFISH and CST Microwave studio. 2.3 MW input power is considered according to MG5193 magnetron. The coupling coefficient is calculated equal to 3% for stabilization of accelerator operation against environmental and mechanical errors effects.

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THPRI048

Design of an Accelerating Tube for a Standing-wave Accelerator based on Genetic Algorithm’s Optimal Calculation

impedance, electron, simulation, radiation

3875

Z.X. Tang
USTC, Hefei, Anhui, People's Republic of China
Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

A compact medical standing-wave (SW) electron accelerating tube has been designed that operating frequency is 2998MHz, operating mode is π/2, final energy is 6MeV and beam current is 100mA based on genetic algorithm (GA)’s optimal calculation. It employed a bi-periodic structure with nose cone shape. We performed the simulation experiment which proved that GA was feasible and gave a set of geometric parameter with higher shunt impedance. We performed tuning of the whole tube by CST MICROWAVE STUDIO and SUPERFISH and calculation of beam dynamics by ASTRA and Parmela in this paper. The total length of the tube is less than 300mm.

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THPRI051

Fabrication and Tests of the Re-buncher Cavities for the LIPAc Deuteron Accelerator

cavity, vacuum, pick-up, simulation

3884

D. Gavela, P. Abramian, J. Calero, A. Guirao, J.L. Gutiérrez, E. Molina Marinas, I. Podadera, L. Sánchez, F. Toral
CIEMAT, Madrid, Spain

Funding: This work has been partially funded by the Spanish Ministry of Economy and Competitiveness under project AIC-A-2011-0654
Two re-buncher cavities will be installed at the Medium Energy Beam Transport (MEBT) of the LIPAc accelerator, presently being built at Rokkasho (Japan). They are IH-type cavities with 5 gaps and will provide an effective voltage of 350 kV at 175 MHz. The cavity consists of a cylindrical main body and two endplates in stainless steel with an internal copper coating. The stems and drift tubes are machined from bulk OFE copper. The fabrication techniques for the cooling pipes, the input coupler and the pick-up are presented. Material choices and fabrication process are discussed. The first re-buncher is already fabricated. RF low power tests have been made to measure resonant frequency, S-parameters and Q-factor before and after the copper plating. The electric field map has also been measured with the bead-pull method.

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THPRI075

S-Band Structure Study for the MaRIE Project

wakefield, dipole, impedance, linac

3940

Z. Li, C. Adolphsen, M.V. Fazio, S.G. Tantawi, L. Xiao
SLAC, Menlo Park, California, USA

Funding: Work was supported by the US Department of Energy through the LANL/LDRD Program.
The Matter-Radiation Interactions in Extremes (MaRIE) facility proposed at LANL utilizes a 20-GeV electron linac to drive a 50-keV XFEL. Experimental requirements drive a need for multiple photon bunches over time durations of about 10 microsecond produced by a bunch train of interleaving 0.1 nC very low-emittance bunches with 2-nC electron bunches. The linac is required not only to provide high gradient and high efficient acceleration, but also a controlled wakefield profile to maintain the beam quality. In this paper, we explore the feasibility of using the S-Band technology to meet such acceleration requirements. We will present the design optimization and comparison of S-Band structures based on different design considerations.

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THPRI080

The New Design for Capture Cavity of CEBAF

cavity, electron, acceleration, simulation

3955

S. Wang, J. Guo, R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

In CEBAF, the electron beam from the injector must be sufficiently relativistic to match a 1 GeV recirculated beam in the first linac. The electron beam is produced with a ~130 keV electron gun, then accelerated by a room temperature, graded-beta standing wave linac, capture section, from 130 keV to 510 keV before enters two 5-cell superconducting RF cavities for further acceleration. Present capture cavity is a 5-cell side-coupled cavity. We designed a new slot-coupled cavity which has lower power consumption and simpler structure.

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THPRI103

Improvement of the Run-time of 35 mbar Helium Gas Pumping Units for the Superconducting Linear Accelerator S-DALINAC

operation, controls, experiment, vacuum

4019

J. Conrad, F. Hug, T. Kürzeder, N. Pietralla
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG through SFB 634
The superconducting Darmstadt linear accelerator S-DALINAC has been designed to provide electron beams of up to 130 MeV for nuclear and astrophysical experiments. The accelerating cavities are operated in a liquid helium bath at 2 K. To achieve this temperature the cryostat has to be pumped down to a pressure of 35 mbar which was done by a system of pumping units connected in series, when the accelerator started its operation in 1991. In 2005 this system was replaced by four parallel switched pumping stations. In the first three years of their operation, the reliability of the accelerator was very poor due to repeated breakdowns of the pumping stations caused by overheating. In addition the high temperatures lead to an early decay of the gaskets used. The problem was solved by installing oil cooling systems and more appropriate shaft sleeves at the pumping stations. We will report on the technical efforts we made and thereby further increased the availability of the accelerator significantly. Also we will give a review on our experiences in maintenance procedures.

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FRYCA01

Options and Prospects for the Future of Accelerator-based High-energy Physics

collider, detector, proton, luminosity

4079

F. Gianotti
CERN, Geneva, Switzerland

Recent results from the LHC and other facilities have significantly impacted the landscape of particle physics. This talk summarises the main outstanding questions in high-energy physics and the strategy to address them. Options for future accelerator facilities and their motivations are discussed.

Slides FRYCA01 [16.139 MB]

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