IPAC2014 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
MOYBA02	New Design Approaches for High Intensity Superconducting Linacs – The New ESS Linac Design	cryomodule, linac, klystron, emittance	23
	D.P. McGinnis ESS, Lund, Sweden
	The cost of the next generation of high intensity accelerators has become so large that no single institution can solely afford to fund the construction of the project. To fund these large projects, institutions have embarked on forming ambitious collaboration structures with other laboratories. To induce other laboratories to join the collaboration, compromises must be made in the accelerator technical design to offer interesting and challenging projects to partner institutions. The cost of high intensity hadron accelerators is largely driven by RF system. A new design philosophy different from the traditional approach is emerging for the high intensity frontier machines. Emittance preservation is often less of an issue as long as beam losses are kept low. At ESS modifications were introduced to the linac design. One of the major changes is the reduction of final energy and an increase of gradient and beam current. As a result the design now meets the cost objective but for the price of a higher risk. The accelerator system designer must then try to balance the cost and technical risks while also satisfying the interests and external goals of the partner laboratories.
	Slides MOYBA02 [2.277 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOYBA02
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MOOCA02	RF Design and Operation of a Modular Cavity for Muon Ionization Cooling R&D	instrumentation, solenoid, vacuum, operation	42
	Y. Torun IIT, Chicago, Illinois, USA D.L. Bowring, M.A. Palmer, K. Yonehara Fermilab, Batavia, Illinois, USA
	Funding: Supported by the US Department of Energy Office of Science through the Muon Accelerator Program. Ionization cooling channel designs call for the operation of high-gradient, normal-conducting RF cavities in multi-Tesla solenoidal magnetic fields. However, strong magnetic fields have been shown in some cases to limit the maximum achievable gradient in RF cavities. This gradient limit is characterized by RF breakdown and damage to the cavity surface. To study this issue, we have developed an experimental program at Fermilab's MuCool Test Area (MTA) based on a modular pillbox cavity operating at 805 MHz. The modular cavity design allows for the evaluation of different cavity geometries and materials – such as beryllium – which may ameliorate or circumvent RF breakdown triggers. We present a summary of recent results and plans for the future of the MTA normal conducting RF cavity program.
	Slides MOOCA02 [32.552 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOOCA02
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MOZB01	Superconducting RF Guns: Emerging Technology for Future Accelerators	gun, cathode, SRF, laser	4085
	J. Teichert HZDR, Dresden, Germany
	This talk should give an overview of Superconducting photo injectors (SRF guns) and focus on the present status of SRF gun development, the technical requirements and the critical issues like cavity design, photocathode integration, and emittance compensation methods.
	Slides MOZB01 [22.198 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOZB01
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MOPRO011	Employing Twin Crabbing Cavities to Address Variable Transverse Coupling of Beams in the MEIC*	electron, solenoid, proton, coupling	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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MOPRO013	Present Status of Coherent Electron Cooling Proof-of-Principle Experiment	electron, ion, gun, experiment	87
	V. Litvinenko, Z. Altinbas, D.R. Beavis, S.A. Belomestnykh, I. Ben-Zvi, K.A. Brown, J.C. Brutus, A.J. Curcio, L. DeSanto, C. Folz, D.M. Gassner, H. Hahn, Y. Hao, C. Ho, Y. Huang, R.L. Hulsart, M. Ilardo, J.P. Jamilkowski, Y.C. Jing, F.X. Karl, D. Kayran, R. Kellermann, N. Laloudakis, R.F. Lambiase, G.J. Mahler, M. Mapes, W. Meng, R.J. Michnoff, T.A. Miller, M.G. Minty, P. Orfin, A. Pendzick, I. Pinayev, F. Randazzo, T. Rao, J. Reich, T. Roser, J. Sandberg, T. Seda, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, L. Snydstrup, A.N. Steszyn, R. Than, C. Theisen, R.J. Todd, J.E. Tuozzolo, E. Wang, G. Wang, D. Weiss, M. Wilinski, T. Xin, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA G.I. Bell, J.R. Cary, K. Paul, I.V. Pogorelov, B.T. Schwartz, A.V. Sobol, S.D. Webb Tech-X, Boulder, Colorado, USA C.H. Boulware, T.L. Grimm, R. Jecks, N. Miller Niowave, Inc., Lansing, Michigan, USA A. Elizarov SUNY SB, Stony Brook, New York, USA M.A. Kholopov, P. Vobly BINP SB RAS, Novosibirsk, Russia P.A. McIntosh, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Work supported by Stony Brook University and by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The Coherent Electron Cooling Proof of Principle (CeC PoP) system is being installed in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. It will demonstrate the ability of relativistic electrons to cool a single bunch of heavy ions in RHIC. This technique may increase the beam luminosity by as much as tenfold. Within the scope of this experiment, a 112 MHz 2 MeV Superconducting Radio Frequency (SRF) electron gun coupled with a cathode stalk mechanism, two normal conducting 500 MHz single-cell bunching cavities, a 704 MHz 20 MeV 5-cell SRF cavity and a helical undulator will be used. In this paper, we provide an overview of the engineering design for this project, test results and discuss project status and plansd.
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MOPRO069	Progress Status of the Iranian Light Source Facility Laboratory	booster, storage-ring, synchrotron, dipole	240
	J. Rahighi, E. Ahmadi, H. Ajam, M. Akbari, S. Amiri, J. Dehghani, R. Eghbali, S. Fatehi, M. Fereidani, A. Gholampour, A. Iraji, M. Jafarzadeh, B. Kamkari, S. Kashani, P. Khodadoost, H. Khosroabadi, M. Lamehi, M. Moradi, H. Oveisi, S. Pirani, M. Rahimi, N. Ranjbar, R. Rasoli, M. Razazian, A. Sadeghipanah, F. Saeidi, R. Safian, E. Salimi, Kh.S. Sarhadi, O. Seify, M.Sh. Shafiee, A. Shahveh, Z. Shahveh, A. Shahverdi, D. Shirangi, E.H. Yousefi ILSF, Tehran, Iran D. Einfeld CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain H. Ghasem IPM, Tehran, Iran
	The Iranian Light Source Facility Project (ILSF) is a 3 GeV third generation light source with a current of 400 mA which will be built on a land of 50 hectares area in the city of Qazvin, located 150 km West of Tehran. ILSF conceptual design report, CDR, was published in October 2012. To have a competitive leading position in the future, 489.6 m storage ring of ILSF is designed to emphasize on small emittance electron beam( 0.93 nm-rad), high photon flux density, brightness, stability and reliability. Moreover, 40% of 489.6 m ring circumference is straight sections (14×8 m+ 14×6 m) which are long enough for the commonly used insertion devices. Some prototype accelerator components such as high power solid state radio frequency amplifiers, LLRF system, thermionic RF gun, Storage ring H-type dipole and quadruple magnets, Hall probe system for magnetic measurement and highly stable magnet power supplies have been constructed in ILSF R&D laboratory.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO069
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MOPRO091	Fundamental Limits of Velocity Bunching of High-brightness Electron Beams	bunching, electron, emittance, gun	304
	A. Opanasenko, V.V. Mytrochenko NSC/KIPT, Kharkov, Ukraine V.A. Goryashko, V. Zhaunerchyk Uppsala University, Uppsala, Sweden P.M. Salen FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
	The interest in superradiant THz sources based on the coherent transition, synchrotron or undulator radiation grows continuously and such sources require high-quality electron bunches with low emittance, high charge and sub-picosecond (sub-ps) duration. Since accelerator-based THz sources are usually driven by relatively low energy electron bunches of a few tens of MeV, space-charge makes bunch compression to sub-ps level very challenging. In the present work we investigate the feasibility of ballistic bunching down to sub-ps duration while preserving the transverse phase-space quality. We found that in order to compensate for the nonlinear dependency of the arrival time on the energy as well as bunch deformations induced by space-charge effects, one needs to apply a nonlinear energy chirp. This chirp permits to maximize the bunch compression and can be realized by exciting a cavity with higher harmonics of the fundamental frequency. Issues related to synchronizing the harmonics are discussed and the analytical analysis is complemented by simulations with PARMELA.
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MOPRO106	Status of the HZB ERL Prototype BERLinPro	gun, linac, SRF, booster	340
	M. Abo-Bakr, W. Anders, R. Barday, K.B. Bürkmann-Gehrlein, A. Burrill, V. Dürr, A. Jankowiak, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, O. Kugeler, B.C. Kuske, A.N. Matveenko, A. Meseck, A. Neumann, K. Ott, E. Panofski, D. Pflückhahn, J. Rahn, J. Rudolph, M. Schmeißer, S.G. Schubert, O. Schüler, J. Völker, S. Wesch HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association. The Berlin Energy Recovery Linac Prototype BERLinPro is to be constructed at the Helmholtz Zentrum site in Berlin. The aim of the project is to expand the required accelerator physics and technology knowledge mandatory for the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. Since the funding decision in October 2010 the project has entered a phase of detailed planning. Hardware specifications have been defined and various components have been ordered. Furthermore, extensive tests of principal superconducting accelerator components successfully demonstrated the envisaged hardware performance. A summary of the most recent activities together with the details of the project timeline for the coming years are given in this paper.
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MOPRO109	Beam Loss Studies for the KEK Compact-ERL	scattering, simulation, electron, beam-losses	349
	O. Tanaka, T. Furuya, K. Harada, N. Nakamura, H. Sakai, M. Shimada, K. Umemori KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan
	Beam losses due to eﬀects of Touschek, residual gas, intra-beam scattering, and field emission were studied for the KEK compact Energy Recovery Linac (cERL), which is now under commissioning. By studying the beam losses of cERL, we can better understand the loss mechanisms, estimate the beam loss rates, and localize potentially dangerous areas of the beamline for the future 3GeV ERL project. The goal is to achieve a safety low-emittance and high-current beams operation which can help contribute to the beam loss study under 3GeV ERL project. We used existing and modiﬁed ELEGANT routine to perform the simulations. We also developed a MATLAB data analysis algorithm to handle the large amount of information that is outputted from the program. The data obtained then compared with the theoretical estimation to judge the computation’s accuracy.
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MOPRO112	Energy Recovering for Linac RF Injectors	gun, SRF, HOM, linac	356
	V. Volkov, Ya.V. Getmanov, O.A. Shevchenko, N. Vinokurov BINP SB RAS, Novosibirsk, Russia A.N. Matveenko HZB, Berlin, Germany
	The article presents a new design of a CW RF high average current superconducting injector cavity. This design allows recovering energy in the injector, improving beam parameters and energy efficiency, reducing injector size, cost, and avoiding high average power coupler problem.
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MOPRO113	Beam-based HOM Measurements in Cornell's ERL Main Linac Cavity	HOM, dipole, quadrupole, linac	359
	D.L. Hall, A.C. Bartnik, M.G. Billing, D. Gonnella, G.H. Hoffstaetter, M. Liepe, C.E. Mayes Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	A search for HOMs in Cornell’s ERL main linac cavity installed in a Horizontal Test Cryomodule (HTC) has been carried out using a bunch charge modulation method, as part of the effort towards building an Energy Recovery Linac (ERL). The beam-based HOM measurements offer the significant advantage of being able to detect trapped modes invisible to both the RF pickup probes and HOM damping loads, and allow for measuring the R/Q of the modes. For each HOM detected during the search, measurements were taken to determine its nature (monopole, dipole, etc.), frequency, loaded quality factor and shunt impedance. A selection of the most notable modes found is presented, compared to 3D HOM simulations, and their potential impact on the BBU current of the future Cornell ERL is discussed.
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MOPME009	Numerical Calculation of Electromagnetic Fields in Acceleration Cavities under Precise Consideration of Coupler Structures	dipole, electromagnetic-fields, HOM, impedance	394
	C. Liu, W.A. Ackermann2, W.F.O. Müller, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by BMBF under contract 05H12RD5 During the design phase of superconducting radio frequency (RF) accelerating cavities a challenging and difficult task is to determine the electromagnetic field distribution inside the structure with the help of proper computer simulations. Although dissipation due to lossy materials is neglected in the current work, in reality, because energy transfer appears due to the design of the superconducting cavities, the numerical eigenmode analysis based on real-valued variables is no longer suitable to describe the dissipative acceleration structure. Dissipation can appear with the help of dedicated higher order mode (HOM) couplers, the power coupler as well as the beam tube once the resonance frequency is above the cutoff frequency of the corresponding waveguide. At the Computational Electromagnetics Laboratory (TEMF) a robust parallel eigenmode solver based on complex-valued finite element analysis is available. The eigenmode solver has been applied to the TESLA 1.3 GHz and the third harmonic 3.9 GHz nine-cell cavities to determine the resonance frequency, the quality factor and the corresponding field distribution of eigenmodes.
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MOPME014	Automated Mode Recognition Algorithm for Accelerating Cavities	coupling, 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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MOPME017	Study of Higher Order Modes in Multi-Cell Cavities for BESSY-VSR Upgrade	HOM, SRF, dipole, linac	412
	T. Galek, K. Brackebusch, Sh. Gorgi Zadeh, 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. BESSY-VSR is a planned scheme to upgrade the existing BESSY II storage ring to support variable electron pulse lengths. In addition to the present 0.5 GHz energy replenishment cavity, two additional SRF bunch compressing cavities operating at 1.5 GHz (3rd harmonic) and 1.75 GHz (sub-harmonic), will be installed. These cavities are essential to produce short 1.5 ps bunches with current of up to 0.8 mA per bunch. In order to achieve such high beam currents, higher order modes must be damped in the superconducting cavities. In this work we present analysis of higher order modes in cavities with different mid-cell shapes.
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MOPME018	Quantification of Geometric Uncertainties in Single Cell Cavities for BESSY VSR using Polynomial Chaos	simulation, HOM, linac, SRF	415
	J. Heller, T. Flisgen, C. Schmidt, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: Federal Ministry for Research and Education Germany under contract 05K13HR1 The electromagnetic properties of SRF cavities are mostly determined by their shape. Due to fabrication tolerances, tuning and limited resolution of measurement systems, the exact shape remains uncertain. In order to make assessments for the real life behaviour it is important to quantify how these geometrical uncertainties propagate through the mathematical system and influence certain electromagnetic properties, like the resonant frequencies of the structure's eigenmodes. This can be done by using non-intrusive straightforward methods like Monte-Carlo (MC) simulations. However, such simulations require a large number of deterministic problem solutions to obtain a sufficient accuracy. In order to avoid this scaling behaviour, the so-called polynomial chaos (PC) expansion is used. This technique allows for the relatively fast computation of uncertainty propagation for few uncertain parameters in the case of computationally expensive deterministic models. In this paper we use the PC expansion to quantify the propagation of uncertain geometry on the example of single cell cavities used for BESSY VSR as well as to compare the obtained results with the MC simulation.
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MOPME043	Modeling and Simulation of Beam-induced Plasma in Muon Cooling Devices	plasma, simulation, electron, ion	466
	K. Yu SBU, Stony Brook, USA M. Chung, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, Illinois, USA B.T. Freemire IIT, Chicago, Illinois, USA V. Samulyak BNL, Upton, Long Island, New York, USA V. Samulyak SUNY SB, Stony Brook, New York, USA
	Understanding of the interaction of muon beams with plasma in muon cooling devices is important for the optimization of the muon cooling process. We have developed numerical algorithms and parallel software for self-consistent simulation of the plasma production and its interaction with particle beams and external fields. Simulations support the experimental program on the hydrogen gas filled RF cavities in the Mucool Test Area (MTA) at Fermilab. Computational algorithms are based on the electromagnetic particle-in-cell (PIC) code SPACE combined with a probabilistic, macroparticle-based implementation of atomic physics processes such as the absorption of the incident particles, ionization of the absorber material, and the generation and evolution of secondary particles in dense, neutral gas. In particular, we have proposed a novel algorithm for dealing with repetitive incident beam, enabling simulations of long time scale processes. Benchmarks and simulations of the experiments on gas-filled RF cavities and prediction for future experiments are discussed. * kwangmin.yu@stonybrook.edu ** rosamu@bnl.gov
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MOPRI025	Recent Improvement of Cs2Te Photocathodes at HZDR	cathode, gun, vacuum, SRF	642
	R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate HZDR, Dresden, Germany
	Funding: Work supported by the European Community-Research Infrastructure Activity (EuCARD, contract number 227579), and the support of the German Federal Ministry of Education and Research grant 05 ES4BR1/8. The SRF gun has been successfully operated for the radiation source ELBE at HZDR. To achieve higher current and lower beam emittance, a new niobium cavity with superconducting solenoid and a new 13 MHz laser have been recently developed. For this reason, better photocathodes with high quantum efficiency are urgently in demand. In this work we improve the present Cs2Te preparation system for cleaner environment and more precise stoichiometric control than before. A new mask is designed to prevent cesium pollution of the cathode body. Instead of Kapton only alumina ceramics are used for isolation, and the cathode plugs are degassed at higher temperature. New evaporators are installed and tested to obtain an accurate deposition rate. Furthermore, the cathode transfer system is thoroughly cleaned for a better vacuum condition.
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MOPRI027	Dark Current Studies at Relativistic Electron Gun for Atomic Exploration – REGAE	electron, gun, vacuum, operation	649
	H. Delsim-Hashemi, K. Flöttmann DESY, Hamburg, Germany
	Electron diffraction is a tool for exploring structural dynamics of matter. The scattering cross section is orders of magnitude higher for electrons than for X-rays so that only a small number of electrons is required to achieve comparable results. However, the required electron beam quality is extraordinary. To study e. g. proteins a coherence length of 30 nm is required which translates into a transverse emittance of 5 nm at a spot size of 0.4mm. In addition short bunch lengths down to 10 fs and a temporal stability of the same order are required in order to study chemical reactions or phase transitions in pump probe type experiments. These are challenging parameters for an electron source, which demand improvements at many frontiers. Dark current degrades contrast of diffraction patterns in all experiments. Understanding dark-current generation and propagation can lead to better methods to decrease it. In this paper dark current studies that are performed at REGAE will be presented.
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MOPRI030	Basic Design of a 20K C-band 2.6-cell Photocathode RF Gun	gun, simulation, electron, vacuum	658
	T. Tanaka, M. Inagaki, K. Nakao, K. Nogami, T. Sakai LEBRA, Funabashi, Japan M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida KEK, Ibaraki, Japan T.S. Shintomi Nihon University, Tokyo, Japan
	Funding: This research was supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT). A cryocooled C-band photocathode RF gun operating at 20K is under design at Nihon University. The RF gun is of BNL-type 2.6-cell pillbox cavity with a resonant frequency of 5712 MHz. With high-purity Oxygen-free copper used as the cavity material, the quality factor of the cavity is expected to be approximately 60000 from theoretical prediction of the anomalous skin effect at low temperatures. Considering the cooling capacity, initial operation of the RF gun is assumed at a duty factor of 0.01%. The cavity elements designed for low-power test is in preparation for machining. The low-power test at room temperature is scheduled early spring in 2014 before assembled at KEK by means of diffusion bonding technique. Since it is intended for the basic understanding and measurements of low temperature RF properties, the cavity is not equipped with structures for the photocathode assembling or the RF input coupler. The cavity design and the results of RF properties measured at room temperature before diffusion bonding will be reported.
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MOPRI033	Quasi-traveling Wave Side Couple RF Gun Commissioning for SuperKEKB	gun, emittance, cathode, coupling	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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MOPRI034	Development of temporal response measurement system for transmission-type spin-polarized photocathodes	electron, laser, resonance, linear-collider	670
	T. Inagaki, M. Hosaka, Y. Takashima, N. Yamamoto Nagoya University, Nagoya, Japan M. Adachi KEK, Ibaraki, Japan X.G. Jin Institute for Advanced Research, Nagoya, Japan M. Katoh, T. Konomi UVSOR, Okazaki, Japan Y. Okano IMS, Okazaki, Japan
	Spin polarized electron beam is essential for "International Linear Collider". In Nagoya University, transmission-type spin-polarized photocathodes have been developed, and the quantum efficiency of 0.5 % and the polarization of 90 % were achieved,. Recently, we succeeded in making the active layer several times thicker with keeping the spin polarization on the GaAs/GaAsP strain-compensated superlattice photocathode*. Increasing the thickness of the active layer is very advantageous for high quantum efficiency, but might be disadvantageous for pulse response. In order to investigate the pulse response, we have developed a pulse length measurement system by using an RF deflecting cavity. In the measurement, magnetic field induced on the beam axis kicks electron pulse transversely and the pulse length is projected to the transverse plane, which is measured by knife-edge method. The pump laser pulses are provided by a Ti:sapphire laser oscillator. By using a pulse stretcher, the pulse width of the pump laser can be changed in the range between 130 fs and 20 ps. In the poster session, we will describe the details of the measurement system and the most recent experimental results. T. Nakanishi, The XXI International LINAC Conference(1998) Xiuguang Jin, Japanese Journal of Applied Physics 51 (2012) 108004 * Xiuguang Jin, Applied Physics Express 6 (2013) 015801
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MOPRI035	Development of the Photocathode LiTi2O4 and Evaluations of the Initial Emittance	cathode, laser, electron, emittance	673
	R. Inagaki, M. Hosaka, Y. Takashima, N. Yamamoto Nagoya University, Nagoya, Japan T. Hitosugi, S. Shiraki Tohoku Uneversity, WPI-AIMR, Sendai, Japan E. Kako, Y. Kobayashi, S. Yamaguchi KEK, Ibaraki, Japan M. Katoh, T. Konomi, T. Tokushi UVSOR, Okazaki, Japan Y. Okano IMS, Okazaki, Japan
	In UVSOR, the X-ray free electron laser (XFEL) based on linear accelerator with high pulse repetition about 1MHz has been designed as a candidate for the next radiation sources. We thought a combination of superconducting RF cavity and photocathode is an optimal electron gun for the new accelerator. For this electron gun, we propose a back-illuminated multi-alkali* photocathode with transparent superconductor LiTi2O4*. The reason for using LiTi2O4 is to reflect RF by using feature of penetration depth of superconductor, which is defined from London equation. This feature protects optical components from RF damage. However, LiTi2O4 is a new material and properties are not clear. We have measured the basic properties of this photocathode, such as magnetic susceptibility measurement and photoelectron spectrometry, etc. In this conference, we will explain the detail of the concept and advantage of this cathode, and show the result measured about the basic properties of this photocathode focusing on the initial emittance measurement. A. V. Lyashenko et al. JINST 4 P07005 (2009) ** Kumatani et al. APL 101 (2012) 123103″
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MOPRI039	Ultra-short Electron Bunch Generation using Energy-chirping Cell Attached RF Electron Gun	gun, electron, simulation, radiation	685
	K. Sakaue, Y. Koshiba, M. Mizugaki, M. Washio Waseda University, Tokyo, Japan R. Kuroda AIST, Tsukuba, Ibaraki, Japan T. Takatomi, J. Urakawa KEK, Ibaraki, Japan
	Funding: Work supported by JSPS Grant-in-Aid for Young Scientists (B) 23740203 and Scientific Research (A) 10001690 We have been developing an Energy-Chirping-Cell attached RF electron gun (ECC-RF-Gun) for generating ultra-short electron bunches. ECC-RF-Gun has extra cell at the end of gun cavity in order to chirp the bunch energy. Such a bunch can be compressed by the velocity difference though the drift space. We have already installed it to our accelerator system and successfully observed a coherent synchrotron/transition radiation at 0.3THz. It is clear that the bunch length was short enough to generate 0.3THz, which corresponds to less than 500fs bunch length was achieved if we assume the gaussian shape. In this conference, the principle of ECC-RF-Gun, the recent results of bunch length measurement and future prospective will be presented.
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MOPRI054	Status of the APEX Project at LBNL	gun, cathode, FEL, linac	727
	F. Sannibale, K.M. Baptiste, C.W. Cork, J.N. Corlett, S. De Santis, L.R. Doolittle, J.A. Doyle, D. Filippetto, G.L. Harris, G. Huang, H. Huang, R. Huang, T.D. Kramasz, S. Kwiatkowski, R.E. Lellinger, V. Moroz, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, H.J. Qian, J.W. Staples, M. Vinco, S.P. Virostek, R.P. Wells, M.S. Zolotorev LBNL, Berkeley, California, USA R. Huang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL), consists in the development of an injector designed to demonstrate the capability of the VHF gun, a normal conducting 186 MHz RF gun operating in CW mode, to deliver the brightness required by X-ray FEL applications at MHz repetition rate. APEX is organized in 3 main phases where different aspects of the required performance are gradually demonstrated. The status and future plans for the project are presented.
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MOPRI056	Design and Fabrication of a VHF - CW High Repetition Rate Electron Gun	cathode, gun, vacuum, operation	733
	R.P. Wells, B. Ghiorso, F. Sannibale, J.W. Staples LBNL, Berkeley, California, USA T.M. Huang IHEP, Beijing, People's Republic of China
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 A high repetition rate, MHz, electron source is a key element in future FEL based light sources. The Advance Photo-injector Experiment (APEX) at Lawrence Berkeley National Laboratory (LBNL) consists of a high repetition rate 186 MHz (VHF-band) CW electron gun, 1 MHz UV laser source and the diagnostic components necessary to quantify the gun’s performance. The gun design is based on well established, conventional RF cavity design, with a couple notable exceptions. The basis for the selection of this technology, novel design features, fabrication techniques and measured cavity performance are presented.
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MOPRI064	First Test Results from SRF Photoinjector for the R&D ERL at BNL	gun, SRF, cathode, electron	748
	D. Kayran, Z. Altinbas, D.R. Beavis, S.A. Belomestnykh, I. Ben-Zvi, J. Dai, S. Deonarine, D.M. Gassner, R.C. Gupta, H. Hahn, L.R. Hammons, C. Ho, J.P. Jamilkowski, P. Kankiya, N. Laloudakis, R.F. Lambiase, V. Litvinenko, G.J. Mahler, L. Masi, G.T. McIntyre, T.A. Miller, D. Phillips, V. Ptitsyn, T. Rao, T. Seda, B. Sheehy, K.S. Smith, A.N. Steszyn, T.N. Tallerico, R. Than, R.J. Todd, E. Wang, D. Weiss, M. Wilinski, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi, J. Dai, L.R. Hammons, V. Litvinenko, V. Ptitsyn Stony Brook University, Stony Brook, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE and DOE grant at Stony Brook, DE-SC0005713. An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is presently under commissioning at Brookhaven National Laboratory (BNL). This facility enables testing of concepts relevant for high-energy coherent electron cooling, electron-ion colliders, and high repetition rate Free-Electron Lasers. The ERL will be capable of providing electron beams with sufficient quality to produce high repetition rate THz and X-ray radiation. When completed the SRF photoinjector will provide 2 MeV energy and 300 mA average beam current. The injector for the R&D ERL was installed in 2012, this includes a 704MHz SRF gun* with multi-alkali photocathode, cryo-system upgrade and a novel emittance preservation zigzag-like low energy merger system. We describe the design and major components of the R&D ERL injector then report the first experimental results and experiences learned in the first stage of beam commissioning of the BNL R&D ERL. * Wencan Xu et al., “Commissioning SRF gun for the R&D ERL at BNL”, IPAC2013 proceedings, WEPWO085.
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MOPRI072	Simulation Study of Heavy Ion Beam Injection and Acceleration in the HESR for Internal Target Experiments with Cooling	target, ion, experiment, acceleration	768
	H. Stockhorst, B. Lorentz, R. Maier, D. Prasuhn, R. Stassen FZJ, Jülich, Germany T. Katayama Nihon University, Narashino, Chiba, Japan
	Recently, the feature of ion beam injection, storage and acceleration assisted by a barrier bucket and cooling has been investigated in the High Energy Storage Ring HESR at the new facility FAIR which will be built at the GSI Darmstadt. A bare uranium beam is injected from the collector ring CR into the HESR at 740 MeV/u. The simulation studies are now improved to include different injection schemes applying either the barrier cavity or the h = 1 cavity in the HESR. It is outlined how the new 2.5 MeV electron cooler at COSY Jülich or stochastic cooling can support the injection mechanism. The beam preparation for an internal target experiment with cooling is outlined. The acceleration of the ion beam is extended to 5 GeV/u under the mandatory condition of the available cavity voltages and the maximum magnetic field ramp rate in the HESR. The flexibility of the HESR ring lattice is utilized to avoid transition energy crossing during ramping up to 5 GeV/u and to adjust the rings’ frequency slip factor for optimal stochastic cooling. The cooling simulations include the beam-target interaction due to a hydrogen target. H. Stockhorst et al., MOPEA018, IPAC13
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MOPRI093	Technical Design of Normal Conducting Re-buncher in the MEBT for Rare Isotope Science Project	rfq, acceleration, ion, operation	830
	H.J. Kim, W.K. Han, I.S. Hong, D. Jeon IBS, Daejeon, Republic of Korea
	Funding: This work was supported by the RISP of Institute for Basic Science funded by Ministry of Science, ICT and Future Planning and National Research Foundation of Korea.(2011-0032011) The front-end system of RISP heavy-ion accelerator(RAON) consists of an electron cyclotron resonance ion source, a low energy beam transport line, a radio frequency quadrupole accelerator and a medium energy beam transport(MEBT) line. The MEBT system, which consists of quadrupole magnets, three normal-conducting re-bunchers and diagnostic devices, is installed between the RFQ accelerator and the superconducting linac(SCL). The three normal-conducting re-bunchers are used to minimize the growths of the longitudinal emittance and to manipulate the particle distribution on longitudinal phase space for beam transportation in SCL. Several combination of the number of cavities was examined, and the quarter wave resonator(QWR) type re-buncher was chosen for MEBT line in RAON. The QWR cavity has a frequency of 81.25 MHz, a maximum electric field of 2.53 MV/m on the cavity surface with an electric field of 1 MV/m on the beam axis, a geometrical beta factor of 0.032 and an effective length of 24 cm. In this presentation, I will present the results of baseline design for electro-magnetic field analysis and mechanical design for stress analysis, thermal stress analysis and cooling channel.
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MOPRI103	Longitudinal Bunch Shortening for the Laser Stripping Project	laser, focusing, linac, acceleration	861
	T.V. Gorlov, A.V. Aleksandrov, S.M. Cousineau, V.V. Danilov, Y. Liu, M.A. Plum ORNL, Oak Ridge, Tennessee, USA
	Funding: This work is funded by the U.S. DOE under grant number DE-FG02-13ER41967, and by the U.S. DOE under contract number DE-AC05-00OR22725 with UT-Battelle Corporation. Realization of high efficiency laser stripping at the SNS accelerator needs good longitudinal overlap between H⁻ bunch and laser pulse. The default H⁻ bunch length at the interaction point is 5 times bigger than needed in order to achieve 90% stripping efficiency. Theoretical and experimental studies of longitudinal H⁻ bunch shortening are presented in this paper.
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TUOBA02	Design Study of an ERL Test Facility at CERN	electron, cryomodule, linac, optics	921
	E. Jensen, C. Bracco, O.S. Brüning, R. Calaga, N. Catalán Lasheras, B. Goddard, R. Torres-Sanchez, A. Valloni CERN, Geneva, Switzerland M. Klein The University of Liverpool, Liverpool, United Kingdom
	The modern concept of an Energy Recovery Linac allows providing large electron currents at large beam energy with low power consumption. This concept is used in FEL’s, electron-ion colliders and electron coolers. CERN has started a Design Study of an ERL Test Facility with the purpose of 1) studying the ERL principle, its specific beam dynamics and operational issues, as relevant for LHeC, 2) providing a test bed for superconducting cavity modules, cryogenics and integration, 3) studying beam induced quenches in superconducting magnets and protection methods, 4) providing test beams for detector R&D and other applications. It will be complementary to existing or planned facilities and is fostering international collaboration. The operating frequency of 802 MHz was chosen for performance and for optimum synergy with SPS and LHC; the design of the cryomodule has started. The ERL Test Facility can be constructed in stages from initially 150 MeV to ultimately 1 GeV in 3 passes, with beam currents of up to 80 mA. Parameters to serve the above-mentioned purposes are well defined and possible lattice designs have well advanced.
	Slides TUOBA02 [14.419 MB]
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TUZA01	Advanced Concepts and Challenges in Compton Radiation Sources	laser, electron, plasma, photon	928
	I. Pogorelsky BNL, Upton, Long Island, New York, USA
	Ongoing developments in Compton radiation sources are aimed toward a diversity of potential applications, ranging from university-scale compact x-ray light sources and metrology tools for EUV lithography, to positron sources for e⁻e⁺ colliders. Novel conceptual approaches are pursued on different routes: One research direction lies in multiplying the source’s repetition rate and increasing its average brightness by placing the point of Compton interaction inside an optical cavity. High-gradient plasma-wakefield accelerators are fast becoming a practical reality, offering a new paradigm to compact all-optical Compton sources operating in x-ray- and gamma-regions. Continuing improvement in the quality of the beam of plasma accelerators promises the achievement of fully coherent Compton x-rays, thereby prompting the evolution of the Compton source to an all-optical free-electron laser.
	Slides TUZA01 [22.419 MB]
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TUXB01	Recent Progress in 3D Numerical Wakefield Calculations	impedance, electron, insertion, damping	944
	W. Bruns WBFB, Berlin, Germany
	The 3D electromagnetic Field Simulator GdfidL computes Wakepotentials on standard CPUs with a Speed comparable to GPU-Based Implementations. This is achieved via Computing only in interesting Cells, having the FD-Coefficients in compressed Form, traversing the Grid in a Cache-friendly Order and applying a blocked Update Scheme which is NuMA-aware. A Dispersion optimised Scheme is described. Fields in dispersive Materials are computed via solving the Equations of the Electron Hulls of the Material. Moving Mesh Computations have the Grid-generation on the Fly.
	Slides TUXB01 [16.169 MB]
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TUOAB01	Computation of Eigenmodes in Long and Complex Accelerating Structures by Means of Concatenation Strategies	factory, HOM, coupling, 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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TUPRO001	Alternative High Luminosity LHC Matching Section Layout	optics, injection, quadrupole, luminosity	990
	B. Dalena, A. Chancé CEA/IRFU, Gif-sur-Yvette, France R. De Maria CERN, Geneva, Switzerland J. Payet CEA/DSM/IRFU, France
	Funding: The research leading to these results has received funding from the European Commission under the FP7 project HiLumi LHC, GA no. 284404, co-funded by the DoE, USA and KEK, Japan. In the framework of the HL-LHC Upgrade project possible variants for the layout of the LHC matching section located in the high luminosity insertions are investigated. This layout is optimized to reduce the demand on the voltage of the crab cavities, it also improves the optics squeeze-ability, both in ATS[1] and non-ATS mode. Moreover the injection and transitions to collision optics are also discussed. [1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.
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TUPRO006	Strong-strong Beam-beam Simulation for the LHC Upgrade	emittance, simulation, resonance, luminosity	1006
	J. Qiang, S. Paret LBNL, Berkeley, California, USA G. Arduini, T. Pieloni CERN, Geneva, Switzerland J. Barranco García EPFL, Lausanne, Switzerland
	Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 using computing resources at the NERSC. The LHC upgrade will significantly improve the performance of the current LHC operation with higher collision energy and luminosity. In the paper, we report on the progress in the strong-strong beam-beam simulation of the HL-LHC upgrade with crab cavity compensation. We will present the study of the effects of accelerator tune working points, dipole noise, and crab cavity noise on colliding beam emittance growth.
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TUPRO013	Studies on Stochastic Cooling of Heavy Ions in the LHC	kicker, luminosity, ion, pick-up	1030
	M. Schaumann, J.M. Jowett, B. Salvant, M. Wendt CERN, Geneva, Switzerland M. Blaskiewicz, S. Verdú-Andrés BNL, Upton, Long Island, New York, USA
	Future high luminosity heavy-ion operation of the LHC will be dominated by very rapid luminosity decay due to the large collision cross-section and, to a lesser extent, emittance growth from intra-beam scattering (IBS) due to the high bunch intensities. A stochastic cooling system could reduce the emittance far below its initial value and reduce the losses from debunching during collisions, allowing more of the initial beam intensity to be converted into integrated luminosity before the beams are dumped. We review the status of this proposal, system and hardware properties and potential locations for the equipment in the tunnel.
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TUPRO016	Machine Protection Challenges for HL-LHC	extraction, beam-losses, operation, luminosity	1039
	R. Schmidt, T. Bär, J. Wenninger, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland
	LHC operation requires the flawless functioning of the machine protection systems. The energy stored in the beam was progressively increased beyond the 140 MJ range at the end of 2012 at 4 TeV/c. The further increase to 364 MJ expected for 2015 at 6.5 TeV/c should be possible with the existing protection systems. For HL-LHC, additional failure modes are considered. The stored beam energy will increase by another factor of two with respect to nominal and a factor of five more than experienced so far. The maximum beta function will increase. It is planned to install crab cavities in the LHC. With crab cavities, sudden voltage decays within 100 us after e.g. cavity quenches lead to large beam oscillations. Tracking simulations predict trajectory distortions of up to 1.5 σ in the first turn after a sudden drop of the deflecting voltage in a single cavity within 3 turns. The energy of several MJ stored in halo protons that could hit the collimator in case of such events is far above damage level, even if the collimator jaws are made of robust material. In this paper we discuss the challenges for machine protection in the HL-LHC era and possible mitigation strategies.
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TUPRO017	HL-LHC Performance with a 200 MHz RF System	luminosity, impedance, electron, simulation	1043
	R. Tomás, C.O. Domínguez CERN, Geneva, Switzerland S.M. White BNL, Upton, Long Island, New York, USA
	The HL-LHC performance could considerably benefit from having a 200 MHz RF system. This would allow to inject longer bunches with larger bunch intensity from the SPS and to perform bunch length leveling if required. We also consider the possibility of decreasing the crab cavity frequency to increase both virtual peak luminosity and luminous region. Performance estimates of various configurations are presented in this paper.
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TUPRO021	Preliminary Study of Risks and Failure Scenarios for the High Luminosity Experiments in HL-LHC	luminosity, simulation, detector, experiment	1055
	F. Bouly LPSC, Grenoble Cedex, France R. Alemany-Fernández, H. Burkhardt, D. Wollmann CERN, Geneva, Switzerland B. Yee-Rendón CINVESTAV, Mexico City, Mexico
	For the HL-LHC it is planned to basically double the diameter of the triplet quadruple magnets around the high luminosity insertions of the LHC. The high luminosity experiments ATLAS and CMS would like to keep a small central chamber radius close the interaction point. In the context of collider-experiment studies for the high-luminosity upgrade of the LHC, we present a first study of the possible consequences of these changes for the experimental running conditions based on detailed simulations with tracking. We have started to implement crab cavity failures and discuss first results from these simulations.
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TUPRO032	RHIC Performance for FY2014 Heavy Ion Run	luminosity, electron, kicker, ion	1090
	G. Robert-Demolaize, J.G. Alessi, M. Bai, E.N. Beebe, J. Beebe-Wang, S.A. Belomestnykh, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, R. Connolly, T. D'Ottavio, K.A. Drees, A.V. Fedotov, W. Fischer, C.J. Gardner, D.M. Gassner, X. Gu, M. Harvey, T. Hayes, H. Huang, P.F. Ingrassia, J.P. Jamilkowski, N.A. Kling, J.S. Laster, C. Liu, Y. Luo, D. Maffei, Y. Makdisi, M. Mapes, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, A.I. Pikin, P.H. Pile, V. Ptitsyn, D. Raparia, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, C. Schultheiss, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, J.E. Tuozzolo, B. Van Kuik, M. Wilinski, Q. Wu, A. Zaltsman, K. Zeno, W. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. After running uranium-uranium and copper-gold collisions in 2012, the high energy heavy ion run of the Relativistic Heavy Ion Collider (RHIC) for Fiscal Year 14 (Run14) is back to gold-gold (Au-Au) collisions at 100 GeV/nucleon. Following the level of performance achieved in Run12, RHIC is still looking to push both instantaneous and integrated luminosity goals. To that end, a new 56 MHz superconducting RF cavity was installed and commissioned, designed to keep ions in one RF bucket and improve luminosity by allowing a smaller beta function at the interaction point (IP) due to a reduced hourglass effect. The following presents an overview of these changes and reviews the performance of the collider.
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TUPRO046	Beamlines with Two Deflecting Cavities for Transverse-to-Longitudinal Phase Space Exchange	quadrupole, beam-transport, emittance, controls	1129
	V. Balandin, W. Decking, N. Golubeva DESY, Hamburg, Germany
	Optical systems for transverse-to-longitudinal emittance exchange involving single dipole-mode cavity were in great details studied during the last decade theoretically and experimentally. In this paper we discuss the question, if there are any advantages in usage of beamlines utilizing two deflecting cavities instead of one. The general analysis is presented and specific beamline designs are given as examples.
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TUPRO116	Conceptual Design of the Muon Cooling Channel to Incorporate RF Cavities	solenoid, dipole, quadrupole, controls	1325
	S.A. Kahn, G. Flanagan, F. Marhauser Muons, Inc, Illinois, USA M.L. Lopes, K. Yonehara Fermilab, Batavia, Illinois, USA
	Funding: Work supported by U.S. DOE STTR/SBIR grant DE-SC00006266 A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoid, helical dipole and helical quadrupole fields has been shown to provide six-dimensional phase space reduction for muon beams. Such a channel can be implemented by a helical solenoid (HS) composed of short solenoid coils arranged in a helical pattern. The magnetic channel will provide the desired Bphi, Bz, and dBphi/dr along the reference path. The channel must allow enough space for RF cavities which replace energy lost in the absorber material present for the cooling process. The study will describe how to achieve the desired field while allowing sufficient space for the cavities. The limits to this design imposed by the achievable current density in the coils will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO116
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TUPME008	Status of the CLIC-UK R&D Programme on Design of Key Systems for the Compact Linear Collider	feedback, collider, quadrupole, linear-collider	1354
	P. Burrows, R. Ainsworth, T. Aumeyr, D.R. Bett, N. Blaskovic Kraljevic, L.M. Bobb, S.T. Boogert, A. Bosco, G.B. Christian, L. Corner, F.J. Cullinan, M.R. Davis, D. Gamba, P. Karataev, K.O. Kruchinin, A. Lyapin, L.J. Nevay, C. Perry, J. Roberts, J. Snuverink, J.R. Towler JAI, Oxford, United Kingdom R. Ainsworth, T. Aumeyr, S.T. Boogert, A. Bosco, P. Karataev, K.O. Kruchinin, L.J. Nevay, J.R. Towler Royal Holloway, University of London, Surrey, United Kingdom P.K. Ambattu, G. Burt, A.C. Dexter, M. Jenkins, S. Karimian, C. Lingwood, B.J. Woolley Cockcroft Institute, Lancaster University, Lancaster, United Kingdom L.M. Bobb, R. Corsini, D. Gamba, A. Grudiev, A. Latina, T. Lefèvre, C. Marrelli, M. Modena, J. Roberts, H. Schmickler, D. Schulte, P.K. Skowroński, J. Snuverink, S. Stapnes, F. Tecker, R. Tomás, R. Wegner, M. Wendt, W. Wuensch CERN, Geneva, Switzerland J.A. Clarke, S.P. Jamison, P.A. McIntosh, B.J.A. Shepherd STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom N.A. Collomb, D.G. Stokes STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom L. Corner Oxford University, Physics Department, Oxford, Oxon, United Kingdom W.A. Gillespie, R. Pan, M.A. Tyrk, D.A. Walsh University of Dundee, Nethergate, Dundee, Scotland, United Kingdom R.M. Jones UMAN, Manchester, United Kingdom
	Six UK institutes are engaged in a collaborative R&D programme with CERN aimed at demonstrating key aspects of technology feasibility for the Compact Linear Collider (CLIC). We give an overview and status of the R&D being done on: 1) Drive-beam components: quadrupole magnets and the beam phase feed-forward prototype. 2) Beam instrumentation: stripline and cavity beam position monitors, an electro-optical longitudinal bunch profile monitor, and laserwire and diffraction and transition radiation monitors for transverse beam-size determination. 3) Beam delivery system and machine-detector interface design, including beam feedback/control systems and crab cavity design and control. 4) RF structure design. In each case, where applicable, we report on the status of prototype systems and performance tests with beam at the CTF3, ATF2 and CesrTA test facilities, including plans for future experiments.
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TUPME009	A Sub-micron Resolution, Wide-band, Stripline BPM System for Driving Bunch-by-bunch Feed-back and Feed-forward Systems at ATF	feedback, kicker, operation, extraction	1358
	G.B. Christian, D.R. Bett, N. Blaskovic Kraljevic, P. Burrows, M.R. Davis, Y.I. Kim, C. Perry JAI, Oxford, United Kingdom
	A low-latency, sub-micron resolution stripline beam position monitoring (BPM) system has been developed and tested with beam at the KEK Accelerator Test Facility (ATF2), where it has been used as part of a beam stabilisation system. The fast analogue front-end signal processor is based on a single-stage RF down-mixer and a position resolution below 400 nm has been demonstrated for beam intensities of ~1 nC, with single-pass beam. The BPM position data are digitised by fast ADCs on an FPGA-based digital feedback controller, which is used to drive either a pair of kickers local to the BPMs and nominally orthogonal in phase, in closed-loop feedback mode, or a downstream kicker in the ATF2 final focus region, in feedforward mode. The beam jitter is measured downstream of the final focus system with high resolution, low-Q, cavity BPMs, and the relative performance of both systems in stabilising the beam is compared.
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TUPME011	The Status of the Construction of MICE Step IV	solenoid, experiment, emittance, coupling	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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TUPME014	Development of Six-dimensional Helical Muon Beam Cooling Channel for Muon Colliders	emittance, solenoid, collider, magnet-design	1373
	K. Yonehara Fermilab, Batavia, Illinois, USA
	A six-dimensional (6D) helical muon beam cooling channel (HCC) has been developed for a last decade. The practical HCC lattice parameters were optimized for the cooling performance in theoretical and numerical simulations. The HCC design group has been formed and has begun the machine development to realize the channel. Recent accomplishments and present critical issues are discussed in the presentation.
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TUPME023	Overview of a muon capture section for muon accelerators	proton, target, solenoid, bunching	1398
	D. Stratakis, J.S. Berg, H. K. Sayed BNL, Upton, Long Island, New York, USA D.V. Neuffer, P. Snopok Fermilab, Batavia, Illinois, USA P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Work supported by Brookhaven Science Associates, LC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We describe a muon capture section to manipulate the longitudinal and transverse phase-space so that to collect efficiently a muon beam produced from an intense proton source target. We show that this can be achieved by using a set of properly tuned rf cavities that captures the beam into string of bunches and aligns them into nearly equal central energies, and a solenoidal chicane that filters high momentum particles, followed by a proton absorber that reduces the energy of all particles. This work elucidates the key parameters that are needed for successful muon capture, such as the required rf frequencies, rf gradients and focusing field. We discuss the sensitivity in performance against the number of different rf frequencies and accelerating rf gradient.
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TUPME024	A hybrid six-dimensional muon cooling channel with gas filled cavities	emittance, vacuum, lattice, simulation	1401
	D. Stratakis BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Obtaining the desired micron-scale emittances for a Muon Collider requires transporting the muon beam through long sections of a beam channel containing rf cavities, absorbers, and focusing solenoids. Here we discuss possible implementation of high-pressure gas-filled RF cavities in a 6D ionization cooling channel and some technical issues associated with it. The key idea of our scheme is a hybrid approach that uses high-pressure gas to avoid cavity breakdown, along with discrete LiH absorbers to provide the majority of the energy loss. We show that the channel performs as well as the original vacuum rf channel while potentially avoiding degradation in rf gradient associated with the strong magnetic field in the cooling channel.
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TUPME030	The LIGHT Beamline at GSI: Shaping Intense MeV Proton Bunches from a Compact Laser-driven Source	proton, laser, focusing, ion	1419
	S. Busold, O. Deppert, M. Roth TU Darmstadt, Darmstadt, Germany V. Bagnoud, A. Blazevic, S. Busold HIJ, Jena, Germany V. Bagnoud, A. Blazevic, S. Busold, D. Schumacher GSI, Darmstadt, Germany C. Brabetz IAP, Frankfurt am Main, Germany F. Kroll TU Dresden, Dresden, Germany F. Kroll Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
	Laser-based proton acceleration as a source of high intensity multi-MeV-range proton bunches became subject of extensive research during the last 15 years and is discussed as potential candidate for various applications. However, their usage often requires special ways of beam shaping first, as the particles are emitted in a wide energy spectrum and with a large divergence angle from the laser matter interaction point. To handle these characteristics, a test stand has been build at GSI Darmstadt, using a pulsed high field solenoid and a radiofrequency cavity to produce intense collimated proton bunches with low energy spread from a TNSA source. In recent experiments, energy compression of an intense proton bunch around 10 MeV central energy to an energy spread of less than 3% could be demonstrated. The particle numbers were in access of 10⁹ protons and the bunch duration was only a few nanoseconds. Even shorter bunches and thus higher particle intensities are possible. This compact laser-driven proton beamline, available now at GSI, will be introduced and latest experimental results presented.
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TUPME053	Study of the Energy Modulated Electron Cyclotron Resonance Ion Source for the Coupled RFQ-SFRFQ Cavity	coupling, ion, ion-source, 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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TUPME054	Influence of a Vacuum Gap on a Bunch Wakefield in a Circular Waveguide Filled up with Dielectric	vacuum, wakefield, radiation, electromagnetic-fields	1489
	T.Yu. Alekhina, A.V. Tyukhtin, V.V. Vorobev Saint-Petersburg State University, Saint-Petersburg, Russia
	Analysis of electromagnetic field of a particle bunch intersecting several boundaries in a dielectric waveguide is important for the wakefield acceleration technique and other problems of accelerator physics. In previous works we investigated the case of a single boundary in a waveguide. Now we study the electromagnetic field of the bunch moving in a dielectric circular waveguide and crossing a vacuum cavity. The main attention is given to the case when wakefield (Cherenkov radiation) is generated in dielectric. The behavior of the total field depending on distance and time is explored numerically. Analytical estimations are made as well. Influence of the vacuum gap on the wakefield is considered for different lengths of the gap. It is clarified conditions when the vacuum gap does not practically influence on the wakefield. It is noted that the quasi monochromatic wave (the Cherenkov transition radiation) generated in the vacuum region can be used for restoration of the field in the area after the gap. This effect can be achieved for some optimal parameters of the problem. T.Yu. Alekhina, A.V. Tyukhtin, Phys. Rev. ST-AB, v.15, 091302 (2012); T.Yu. Alekhina, A.V. Tyukhtin, Phys. Rev. ST-AB, v.16, 081301 (2013).
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TUPME057	Optimization of Accelerators and Light Sources within oPAC	network, simulation, controls, booster	1499
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485. The optimization of particle accelerators and light sources by combining studies into beam physics, instrumentation, numerical simulations and accelerator control systems is the aim of the EU-funded oPAC project. With a budget of more than 6 M€, oPAC is one of the largest training networks ever funded by the EU and currently trains more than 20 Marie Curie Fellows. This paper presents selected research highlights, including optimization studies into the CERN Proton Synchrotron (PS), measurement and correction of linear and nonlinear optics distortions in the ALBA synchrotron (Spain), perturbation measurements of a cavity Schottky noise detector at GSI (Germany) and R&D into device control data base tool at COSYLAB (Slovenia). Moreover, a summary of past and future oPAC events is also given.
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TUPME059	Longitudinal Bunch Shaping with a Double Dogleg based Emittance Exchange Beam Line	emittance, space-charge, controls, experiment	1506
	G. Ha, M.E. Conde, W. Gai, C.-J. Jing, K.-J. Kim, J.G. Power, A. Zholents ANL, Argonne, Illinois, USA M.-H. Cho, G. Ha, W. Namkung POSTECH, Pohang, Kyungbuk, Republic of Korea C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: Work supported by High Energy Physics, Office of Science, US DOE. A new program is under development at Argonne National Laboratory (ANL) to use an emittance exchange (EEX) beamline to produce longitudinally shaped electron bunches. While the ultimate goal is to generate triangular shapes for high transformer ratio wakefield acceleration we are also exploring, in general, the capability of the double dogleg EEX beamline to control the bunch shape. We are studying effects that degrade the quality of the longitudinal current profile including: non-uniform particle distribution, emittance, the deflecting cavity thick-lens effect, 2nd order effects, space charge effects and coherent synchrotron radiation effects. We will present the double dogleg EEX beamline layout and the diagnostic design as well as give a progress report on the experimental status of the program.
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TUPME084	On the Frequency Choice for the eRHIC SRF Linac	linac, SRF, HOM, electron	1547
	S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, V. Ptitsyn, W. Xu BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, V. Ptitsyn Stony Brook University, Stony Brook, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. eRHIC is a future electron-hadron collider proposed at BNL. It will collide high-intensity hadron beams from one of the existing rings of RHIC with a 50-mA electron beam from a multi-pass 10-GeV superconducting RF (SRF) Energy Recovery Linac (ERL). A novel approach to the multi-pass ERL utilizing a non-scaling FFAG was recently proposed. It has many advantages over the previous designs including significant cost savings. The current design has 11 passes in two FFAG rings. To mitigate various beam dynamics effects, it was proposed to lower RF frequency of the SRF linac from 704 MHz used in the previous design. In this paper we consider different effects driving the frequency choice of the SRF ERL and present our arguments for choosing lower RF frequency.
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TUPRI003	Simulating the Production and Eﬀects of Dark Currents in MICE Steps V and VI	electron, solenoid, experiment, simulation	1556
	C. Hunt, J. Pasternak, M.A. Uchida Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	Funding: STFC The completion of the international Muon Ionisation Cooling Experiment (MICE) Step V will involve the construction, commissioning and use of RF cavity and Coupling Coil (RFCC) Modules. The RFCCs consist of 4 RF cavities and a solenoid magnet, and are expected to act as a source of potentially damaging electrons (dark currents) and X-rays. Ongoing work to create a high-statistics simulation of the dark current production, within RF cavities, is described. Current results predict the energy and angular spectra of emitted electrons for an RFCC, and include particle tracking, realistic field maps and ionisation energy losses in cavity windows. Individual electron emitters, parametrised by the Fowler-Nordheim equation, are used and are user-definable, allowing potential worst-case scenarios to be simulated and upper/lower limits for the total dark current to be estimated. These data are being used within the MICE Analysis and User Software (MAUS) to estimate the potential detector backgrounds and the damage that may be inflicted upon the scintillating fibre trackers.
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TUPRI014	Modelling and Long Term Dynamics of Crab Cavities in the LHC	multipole, luminosity, hadron, experiment	1578
	R. Appleby, D.R. Brett UMAN, Manchester, United Kingdom J. Barranco García, R. De Maria, A. Grudiev, R. Tomás CERN, Geneva, Switzerland
	Funding: The research leading to these results has received funding from the European Commission under the FP7 project HiLumi LHC, GA no. 284404, co-funded by the DoE, USA and KEK, Japan. The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) aims to achieve an integrated luminosity of 250-300 fb-1 per year. This upgrade includes the use crab cavities to mitigate the geometric loss of luminosity arising from the beam crossing angle. The tight space constraints at the location of the cavities leads to cavity designs which are axially non-symmetric and have a potentially significant effect on the long term dynamics and dynamic aperture of the LHC. In this paper we present the current status of advanced modelling of crab cavities.
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TUPRI015	Transverse Emittance Compensation for the Rossendorf SRF Gun II	gun, solenoid, SRF, electron	1582
	H. Vennekate, A. Arnold, P.N. Lu, P. Murcek, J. Teichert, R. Xiang HZDR, Dresden, Germany T. Kamps HZB, Berlin, Germany P. Kneisel JLab, Newport News, Virginia, USA
	Funding: We acknowledge the support of the EU Community-Research Infrastructure Activity under the FP7 program (EuCARD-2, 312453) and of the German Federal Ministry of Education and Research grant 05K12CR1. Superconducting RF particle sources combine the advantages of normal conducting RF sources and high duty cycle non-RF sources. The Rossendorf SRF gun was the first to demonstrate this injecting electrons into the ELBE accelerator at 13 MHz. Recently, a new 3-1/2-gun cavity has been prepared at Jefferson Lab for its use in an updated injector which is expected to increase the electron energy from 2.4 to 7.5 MeV. Along with this new cavity, a new gun cryostat has been introduced. It combines several minor updates to the setup with the installation of a superconducting solenoid right at the exit of the gun, compensating the emittance growth of the electron bunch at an early stage. The poster is going to conclude the results of the commissioning of the new cryostat including the solenoid and compare it to the prior concept using a normal conducting solenoid outside the cryostat. As it is of great importance to this subject, studies of the magnetic shielding are going to be presented as well.
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TUPRI021	Impedance Calculation and Simulation of Microwave Instability for the Main Rings of SuperKEKB	impedance, simulation, vacuum, kicker	1600
	D. Zhou, T. Abe, T. Ishibashi, Y. Morita, K. Ohmi, K. Shibata, Y. Suetsugu, M. Tobiyama KEK, Ibaraki, Japan
	The SuperKEKB B-factory is now under construction. The designs of the components for the SuperKEKB have mostly been finished. This paper summarises the updated results of longitudinal impedance calculations for various components of the main rings. By summing up all available impedances, a pseudo-Green wake function with bunch length of σ_z=0.5 mm is constructed as an impedance model for consequent studies of collective effects. The results of these studies are also reported in this paper.
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TUPRI023	Simulation of Debunching for Slow Extraction in J-PARC MR	beam-loading, resonance, simulation, impedance	1606
	M. Yamamoto, M. Nomura, T. Shimada, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii KEK, Ibaraki, Japan A. Schnase GSI, Darmstadt, Germany
	The J-PARC MR delivers a proton beam for nuclear physics experiments with slow extraction. The beam is debunched at flat top to obtain a coasting beam by turning off the rf voltage. The controlled emittance blow-up before the flat top has been investigated to mitigate the microwave instability. Beam loading effect can disturb the uniformity of the debunching at the flat top. We describe the results of the particle tracking simulation whole acceleration cycle including the controlled emittance blow-up and the beam loading effect.
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TUPRI043	Analysis of Coupled Bunch Instabilities in BESSY-VSR	HOM, feedback, damping, impedance	1659
	M. Ruprecht, P. Goslawski, A. Jankowiak, M. Ries, A. Schälicke, G. Wüstefeld HZB, Berlin, Germany T. Weis DELTA, Dortmund, Germany
	BESSY-VSR, a scheme where 1.5 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed. The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. This paper presents investigations of coupled bunch instabilities driven by HOMs of superconducting multi cell cavities in BESSY-VSR. Analytical calculations and tracking simulations in time domain are performed in the longitudinal and the transverse planes and factors that influence the threshold currents are being discussed. Suitable candidates of cavities which are presently available or in the phase of design are compared with respect to their instability thresholds. G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries, Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proceedings of IPAC2011, San Sebastián, Spain
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TUPRI060	Impedance Studies for the PS Finemet® Loaded Longitudinal Damper	impedance, simulation, kicker, synchrotron	1708
	S. Persichelli, M. Migliorati, M.M. Paoluzzi, B. Salvant CERN, Geneva, Switzerland
	The impedance of the Finemet® loaded longitudinal damper cavity, installed in the CERN Proton Synchrotron straight section 02 during the Long Shutdown 2013-2014, has been evaluated. Time domain simulations with CST Particle Studio have been performed in order to get the longitudinal and transverse impedance of the device and make a comparison with the longitudinal impedance that was measured for a single cell prototype.
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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, coupling, 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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TUPRI069	NSLS-II Commissioning with 500 MHZ 7-CELL PETRA-III Cavity	storage-ring, feedback, accumulation, synchrotron	1724
	A. Blednykh, G. Bassi, W.X. Cheng, J. Choi, Y. Hidaka, S.L. Kramer, Y. Li, B. Podobedov, J. Rose, T.V. Shaftan, G.M. Wang, F.J. Willeke, L.-H. Yu BNL, Upton, Long Island, New York, USA
	The NSLS-II storage ring has been commissioned during Phase 1 with 500 MHz 7-cell PETRA-III RF cavity. In this paper we present our first beam-measured data on instabilities and collective effects with a normal conducting RF system.
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TUPRI070	Analysis of Coupled-bunch Instabilities in the NSLS-II Storage Ring	HOM, impedance, storage-ring, damping	1727
	G. Bassi, A. Blednykh, F. Gao, J. Rose BNL, Upton, Long Island, New York, USA
	We discuss coupled-bunch instabilities thresholds for the NSLS-II Storage Ring. In particular, we analyze thresholds from the High Order Modes (HOMs) of the PETRA-III 7-cell cavity. Beam dynamics simulations with the code OASIS, using the measured HOMs, will be compared with machine studies.
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TUPRI073	Impact of Simplified Stationary Cavity Beam Loading on the Longitudinal Feedback System for SIS100	feedback, synchrotron, beam-loading, controls	1736
	K. Groß, H. Klingbeil, D.E.M. Lens TEMF, TU Darmstadt, Darmstadt, Germany H. Klingbeil GSI, Darmstadt, Germany D.E.M. Lens TU Darmstadt, RTR, Darmstadt, Germany
	Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P12RDRBF. The main synchrotron SIS100 of the Facility for Antiproton and Ion Research (FAIR) will be equipped with a bunch-by-bunch feedback system to damp longitudinal beam oscillations. In the basic layout, one three-tap finite impulse response (FIR) filter will be used for each single bunch and oscillation mode. The detected oscillations are used to generate a correction voltage in dedicated broadband radio frequency (RF) cavities. The digital filter is completely described by two parameters, the feedback gain and the passband center frequency, which have to be defined depending on the longitudinal beam dynamics. In earlier works, the performance of the closed loop control with such an FIR-filter was analyzed and compared to simulations and measurements with respect to the damping of coherent dipole and quadrupole modes, the first modes of oscillation. This contribution analyzes the influence of cavity beam loading on the closed loop performance and the choice of the feedback gain and passband center frequency to verify future high current operation at FAIR. H. Klingbeil et al., IEEE Trans. Nuc. Sci., Vol. 54, No. 6, 2007 and D. Lens et al., Phys. Rev. STAB 16, 032801, 2013.
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TUPRI092	Improvement of the Position Monitor using White Light Interferometer for Measuring Precise Movement of Compact ERL Superconducting Cavities in Cryomodule	target, cryomodule, linac, operation	1787
	H. Sakai, K. Enami, T. Furuya, M. Satoh, K. Shinoe, K. Umemori KEK, Ibaraki, Japan T. Aoto, K. Hayashi, K. Kanzaki Tokyo Seimitsu Co. Ltd, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan M. Sawamura JAEA, Ibaraki-ken, Japan
	Alignment of superconducting cavities is one of the important issues for linear collider and/or future light source like ERL and X-FEL. To measure the cavity displacement under cooling to liquid He temperature more precisely, we newly developed the position monitor by using white light interferometer. This monitor is based on the measurement of the interference of light between the measurement target and the reference point. It can measure the position from the outside of the cryomodule. We applied this monitor to the main linac cryomodule of Compact ERL (cERL) and successfully measured the displacement during 2K cooling with the resolution of 10um. However, some drift come from outer temperature and humidity were observed. In this paper, we describe the upgraded version of this monitor to suppress these drift for cERL beam operation.
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TUPRI104	A Beam Arrival Time Cavity for REGAE at DESY	electron, coupling, 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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WEOBA02	Superconducting Linac for Rare Isotope Science Project	linac, cryomodule, ion, proton	1861
	H.J. Kim, H.J. Cha, M.O. Hyun, H. Jang, H.C. Jung, Y. Kim, M. Lee, G.-T. Park IBS, Daejeon, Republic of Korea
	Rare Isotope Science Project (RISP) has been proposed as a multi-purpose accelerator facility for providing beams of exotic rare isotopes of various energies. The RISP driver linac which is used to accelerate the beam, for an example, Uranium ions from 0.5 MeV/u to 200 MeV/u consists of superconducting RF cavities and warm quadrupole magnets for focusing heavy ion beams. Requirement of the linac design is especially high for acceleration of multiple charge beams. In this paper, we present the status of RISP linac design and the development of superconducting cavity and cryomodule.
	Slides WEOBA02 [9.226 MB]
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WEOCA01	Construction Status of SuperKEKB	dynamic-aperture, controls, detector, damping	1877
	N. Ohuchi, K. Akai, H. Koiso KEK, Ibaraki, Japan
	SuperKEKB consists of 7 GeV electron and 4 GeV positron rings (HER and LER), a newly built positron damping ring and an injector linac. The target luminosity is 8x10³⁵ cm^-2s^-1, which is 40 times higher than that achieved at KEKB. Construction of SuperKEKB is progressing on schedule, and beam commissioning is scheduled in 2015. Fabrication, treatment and installation of vacuum components, magnets and power supplies, and beam diagnostic and feedback systems are ongoing. Improvement of RF system and strengthening of cooling system for magnets and beam pipes are also underway. Detailed design of the interaction region has been finalized, and final focus superconducting magnets are under production. The damping ring tunnel and buildings has been completed, and installation of the accelerator components started. The upgrade of the injector linac is also progressing. This paper describes construction status of SuperKEKB main rings and the damping ring as well as recent design progress.
	Slides WEOCA01 [6.360 MB]
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WEIB03	How To Produce 100 Superconducting Modules for the European XFEL in Collaboration and with Industry	vacuum, quadrupole, SRF, controls	1923
	H. Weise DESY, Hamburg, Germany
	European XFEL accelerator module production is in almost full swing by the time of IPAC 2014. This is the first project of this size that includes many partner laboratories and transfer of technology for mass superconducting RF cavity and accelerator module production to industry. This talk will illustrate the organization of the production and the lessons learned, illuminating what one should or would do differently for future projects.
	Slides WEIB03 [11.584 MB]
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WEIB04	Challenges of the XFEL Cryomodule Integration and Industry Transfer	operation, cryomodule, alignment, target	1929
	F. Chastel, P. Pluvy, H. Rocipon ALSYOM, Argebteuil, France
	The construction of the European XFEL Accelerator is based on in-kind contributions shared by several institutes throughout Europe and Russia. Within the French contribution, CEA is responsible for the assembly, in a dedicated facility located in Saclay, of the up to 100 cryomodules constituting the Linac. Since 2012, ALSYOM has been selected as the industrial partner for such assembly works. This presentation will detail the organization set up for this partnership and the related challenges of this transfer to Industry.
	Slides WEIB04 [1.962 MB]
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WEPRO003	Construction of a Laser Compton Scattered Photon Source at cERL	photon, laser, electron, gun	1940
	R. Nagai, R. Hajima, M. Mori, T. Shizuma JAEA, Ibaraki-ken, Japan T. Akagi, Y. Honda, A. Kosuge, J. Urakawa KEK, Ibaraki, Japan
	A nondestructive assay system of isotopes by quasi-monochromatic gamma-rays and nuclear resonance fluorescence is under development in JAEA. The quasi-monochromatic gamma-rays are generated by laser Compton scattering (LCS) based on energy-recovery linac accelerator and laser technologies. In order to demonstrate the accelerator and laser performance required for the gamma-ray source, an LCS experiment is planned at Compact ERL (cERL) at KEK. A mode-locked fiber laser, laser enhancement cavity, beamline, and experimental hatch are under construction for the LCS experiment. Up-to-date construction status is presented in detail.
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WEPRO005	Development of Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources	HOM, linac, brightness, photon	1946
	M. Sawamura, R. Hajima, R. Nagai JAEA, Ibaraki-ken, Japan H. Fujisawa, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan T. Kubo KEK, Ibaraki, Japan
	Funding: This work is supported by Photon and Quantum Basic Research Coordinated Development Program. We have launched a 5-year research program to develop superconducting spoke cavity for laser Compton scattered (LCS) photon sources. For realizing a wide use of LCS X-ray and gamma-ray sources in academic and industrial applications, we adopt 325-MHz superconducting spoke cavity to electron beam drivers for the LCS sources. The spoke cavity, originally invented for ion and proton acceleration, can be used for electron accelerators, in which we can make best use of features of spoke cavity: relative compactness in comparison with a TM cavity of the same frequency, robustness with respect to manufacturing inaccuracy due to its strong cell-to-cell coupling, couplers on outer conductor for the better packing in a linac, and so on. In this paper, we present our research plan and results of cavity shape optimization.
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WEPRO007	Nanometer Scale Coherent Current Modulation via a Nanotip Cathode Array and Emittance Exchange	electron, emittance, gun, linac	1952
	E.A. Nanni, W.S. Graves MIT, Cambridge, Massachusetts, USA P. Piot Fermilab, Batavia, Illinois, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: NSF DMR-1042342, DARPA N66001-11-1-4192 We present PIC simulations of electron bunches with nm scale longitudinal modulation produced using a compact 2-20 MeV LINAC. The modulation is initially imparted in the transverse dimension of the electron bunch with a nano-patterned photo-emitter in a X-band RF gun with 2 MeV exit energy. The electron bunch passes through a 1 m standing wave X-band LINAC which can raise the beam energy up to 20 MeV. The transverse modulation is exchanged into the longitudinal dimension using a double dog-leg emittance exchange setup with a 5 cell RF deflector cavity. The modulation pitch can be tuned by adjusting the spacing of the nano-patterned photo-emitter or magnification of the transverse pitch with electron optics. The electron beam parameters are optimized to produce coherent XFEL radiation upon interacting with a “laser undulator”.
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WEPRO018	Theoretical Maximum Current of the NSLS-II Linac	linac, simulation, beam-loading, gun	1980
	R.P. Fliller, F. Gao, G.M. Wang BNL, Upton, Long Island, New York, USA
	Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. An analysis of the maximum available NSLS-II linac current was performed as part of the preparation for NSLS-II Booster commissioning. The analysis was necessary in order to establish the maximum beam current available from the linac and the maximum current that would be available to the booster accelerator. In this paper we discuss the assumptions that were used in determining the maximum linac current, the model of the linac and comparison to operational conditions.
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WEPRO052	The ThomX Project Status	laser, framework, synchrotron, gun	2062
	A. Variola, D. Auguste, A. Blin, J. Bonis, S. Bouaziz, C. Bruni, K. Cassou, I. Chaikovska, S. Chancé, V. Chaumat, R. Chiche, P. Cornebise, O. Dalifard, N. Delerue, T. Demma, I.V. Drebot, K. Dupraz, N. El Kamchi, M. El Khaldi, P. Gauron, A. Gonnin, E. Guerard, J. Haissinski, M. Jacquet, D. Jehanno, M. Jouvin, E. Jules, F. Labaye, M. Lacroix, M. Langlet, D. Le Guidec, P. Lepercq, R. Marie, J.C. Marrucho, A. Martens, B. Mercier, E. Mistretta, H. Monard, Y. Peinaud, A. Pérus, B. Pieyre, E. Plaige, C. Prevost, T. Roulet, R. Roux, V. Soskov, A. Stocchi, C. Vallerand, A. Vermes, F. Wicek, Y. Yan, J.F. Zhang, Z.F. Zomer LAL, Orsay, France P. Alexandre, C. Benabderrahmane, F. Bouvet, L. Cassinari, M.-E. Couprie, P. Deblay, Y. Dietrich, M. Diop, M.E. El Ajjouri, M.P. Gacoin, C. Herbeaux, N. Hubert, M. Labat, P. Lebasque, A. Lestrade, R. Lopes, A. Loulergue, P. Marchand, F. Marteau, D. Muller, A. Nadji, R. Nagaoka, J.-P. Pollina, F. Ribeiro, M. Ros, R. Sreedharan SOLEIL, Gif-sur-Yvette, France A. Bravin, G. Le Duc, J. Susini ESRF, Grenoble, France C. Bruyère, A. Cobessi, W. Del Net, J.L. Hazemann, J.L. Hodeau, P. Jeantet, J. Lacipière, O. Proux Institut NEEL, Grenoble, France E. Cormier, J. Lhermite CELIA, Talence, France L. De Viguerie, H. Rousselière, P. Walter LAMS, Universite Pierre et Marie Curie, Ivry Sur Seine, France H. Elleaume, F. Esteve INSERM, Grenoble Institut des Neurosciences, La Tronche, France J.M. Horodinsky, N. Pauwels, P. Robert CNRS (IRSD), Orsay, France S. Sierra TED, Velizy, France
	Funding: Work supported by the French Agence Nationale de la Recherche as part of the program EQUIPEX under reference ANR-10-EQPX-51, the Ile de France region, CNRS-IN2P3 and Université Paris Sud XI A collaboration of seven research institutes and an industry has been set up for the ThomX project, a compact Compton Backscattering Source (CBS) based in Orsay – France. After a period of study and definition of the machine performances a complete description of all the systems has been provided. The infrastructures work is started and the main systems are in the call for tender phase. In this paper we will illustrate the definitive machine parameters and components characteristics. We will also update the results of the different ongoing R&D on optical resonators, fast power supplies for the injection kickers and on the electron gun.
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WEPRO056	Development of an Optical Resonant Cavity for the LCS Experiment at cERL	laser, photon, experiment, resonance	2072
	T. Akagi, Y. Honda, A. Kosuge, J. Urakawa KEK, Ibaraki, Japan R. Hajima, M. Mori, R. Nagai, T. Shizuma JAEA, Ibaraki-ken, Japan
	A nondestructive assay system of isotopes by quasi-monochromatic gamma-rays by laser Compton scattering (LCS) is under development. In order to demonstrate the accelerator and laser performance required for the gamma-ray source, an LCS experiment is planned at Compact ERL (cERL) at KEK. An optical resonant cavity is under construction for the LCS experiment. The new optical cavity is designed by combination of two bow-tie cavities to achieve fast optical polarization switching. The performance of the optical cavity is presented in detail.
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WEPRO064	Recent Results of the HESR RF System	operation, impedance, electron, accumulation	2094
	R. Stassen, F.J. Etzkorn, R. Greven, T. Katayama, R. Maier, G. Schug, H. Stockhorst FZJ, Jülich, Germany
	The FAIR complex (Facility for Antiprotons and Ion Research) will be built in different stages. Due to the postponed RESR in the first stage, both RF-cavities of the HESR have to operate in different modes to achieve the required beam quantity and quality. The RF-system of the HESR will now consists of two identical cavities with a common low-level RF control (LLRF). Both cavities will be driven by low noise solid state amplifiers. Each cavity contains of one gap and two tanks operating in push-pull mode and each tank will house 6 ring cores wound of modern magnetic nano-alloy ribbon. Meanwhile all ring cores were delivered and first results at low power and at high power will be presented. The construction of the new air cooling concept is now in the final stage.
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WEPRO090	Status of KAERI 6 MeV 9.3 GHz X-Band Electron Linac for Cancer Treatment System	linac, electron, gun, radiation	2168
	B.N. Lee, B.C. Lee, S.H. Lee, S. Lee, H.D. Park, K.B. Song KAERI, Dae-jeon, Republic of Korea P. Buaphad, Y. Kim ISU, Pocatello, Idaho, USA S.S. Cha UST, Daejeon City, Republic of Korea
	Funding: This work was supported by a grant from the (NRF funded by the MSIFP, Korea (No.2013M2A2A4023350) and the Industrial Strategic technology development program, 10043897, funded By the MOTIE, Korea. The X-band RF linear accelerators (LINAC’s) are popular for medical application due to its compactness. To increase the precision of treatment accuracy under circumstance in which the LINAC is mounted on an apparatus such as gantry frame or robot-arm; this is an advantage as the weight and size are more reduced. It is a 9.3 GHz magnetron with the most readily available RF generator in the X-band frequencies from 8 GHz to 12 GHz and the magnetron is mainly used for the source of the RF power in a compact LINAC. The average power of the magnetron at 9.3~GHz is generally a few MW and this amount could provide a sufficient radiation dose-rate for tumour therapy. KAERI has been developing a new compact 9.3 GHz X-band electron LINAC for a cancer treatment system. The maximum energy of the electron beam is 6 MeV and the average beam power at the tungsten target is about 1 kW. In this paper, we describe the status of development of the 6 MeV X-band LINAC at KAERI.
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WEPRO096	X-ray Radiation Source for Low Dose Angiography based on Channeling Radiation	radiation, electron, optics, photon	2186
	S.M. Polozov, T.V. Bondarenko MEPhI, Moscow, Russia
	Angiography is one of the most reliable and contemporary procedure of the vascular system imaging. X-ray spectrums provided by all modern medical angiographs are too broad to acquire high contrast images and provide low radiation dose at the same time. The new method of narrow X-ray spectrum achieving is based on the idea of channelling radiation application. The X-ray filters used in this method allows eliminating the high energy part of the spectrum and providing dramatic dose reduction. The scheme of the facility including the X-ray filter is discussed. The results of the spectrum analysis for the channelling radiation source and typical angiography X-ray tube are discussed. Doses obtained by the water phantom and contrast of the iodine agent image are also provided for both cases.
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WEPME002	Laser System for SNS Laser Stripping Experiment	laser, controls, experiment, neutron	2254
	Y. Liu, C. Huang, A. Rakhman ORNL, Oak Ridge, Tennessee, USA
	Funding: This work is funded by the U.S. DOE under grant number DE-FG02-13ER41967, and by the U.S. DOE under contract number DE-AC05-00OR22725 with UT-Battelle Corporation. The Spallation Neutron Source (SNS) accelerator complex utilizes charge-exchange injection to stack a high-intensity proton beam in the accumulator ring for short-pulse neutron production. A foil-less charge exchange injection method was researched at SNS by using a laser assisted H⁻ beam stripping scheme. Following a proof-of-principle experiment using a Q-switched laser, a new experiment is being prepared to demonstrate laser stripping over a 10-us macropulse. In this talk, we will report the design and measurement results of the laser system for the next stage laser stripping experiment. The laser system adopts a master oscillator power amplifier (MOPA) configuration and contains an actively mode-locked fiber seeder, macropulse generator, multiple-stage Nd:YAG amplifiers, harmonic converters, and control electronics. The laser system generates 50 ps/402.5 MHz pulses (at a macropulse mode) with multiple megawatt peak power at a wavelength of 355 nm. The measurement results of laser pulse width, spectrum, spatial/temporal beam quality and their parameter dependence will be described.
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WEPME003	Two Years Experience with the Upgraded ELBE RF System Driven by 20kW Solid State Amplifier Blocks (SSPA)	operation, klystron, linac, SRF	2257
	H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert HZDR, Dresden, Germany
	Since January 2012 the Superconducting CW Linac ELBE is equipped and in permanent operation with four 20 kW Solid State Amplifier Blocks. The poster gives an overview on the design of the new RF system and the experience gained within the first two years of operation.

Paper

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MOYBA02

New Design Approaches for High Intensity Superconducting Linacs – The New ESS Linac Design

cryomodule, linac, klystron, emittance

23

D.P. McGinnis
ESS, Lund, Sweden

The cost of the next generation of high intensity accelerators has become so large that no single institution can solely afford to fund the construction of the project. To fund these large projects, institutions have embarked on forming ambitious collaboration structures with other laboratories. To induce other laboratories to join the collaboration, compromises must be made in the accelerator technical design to offer interesting and challenging projects to partner institutions. The cost of high intensity hadron accelerators is largely driven by RF system. A new design philosophy different from the traditional approach is emerging for the high intensity frontier machines. Emittance preservation is often less of an issue as long as beam losses are kept low. At ESS modifications were introduced to the linac design. One of the major changes is the reduction of final energy and an increase of gradient and beam current. As a result the design now meets the cost objective but for the price of a higher risk. The accelerator system designer must then try to balance the cost and technical risks while also satisfying the interests and external goals of the partner laboratories.

Slides MOYBA02 [2.277 MB]

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MOOCA02

RF Design and Operation of a Modular Cavity for Muon Ionization Cooling R&D

instrumentation, solenoid, vacuum, operation

42

Y. Torun
IIT, Chicago, Illinois, USA
D.L. Bowring, M.A. Palmer, K. Yonehara
Fermilab, Batavia, Illinois, USA

Funding: Supported by the US Department of Energy Office of Science through the Muon Accelerator Program.
Ionization cooling channel designs call for the operation of high-gradient, normal-conducting RF cavities in multi-Tesla solenoidal magnetic fields. However, strong magnetic fields have been shown in some cases to limit the maximum achievable gradient in RF cavities. This gradient limit is characterized by RF breakdown and damage to the cavity surface. To study this issue, we have developed an experimental program at Fermilab's MuCool Test Area (MTA) based on a modular pillbox cavity operating at 805 MHz. The modular cavity design allows for the evaluation of different cavity geometries and materials – such as beryllium – which may ameliorate or circumvent RF breakdown triggers. We present a summary of recent results and plans for the future of the MTA normal conducting RF cavity program.

Slides MOOCA02 [32.552 MB]

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MOZB01

Superconducting RF Guns: Emerging Technology for Future Accelerators

gun, cathode, SRF, laser

4085

J. Teichert
HZDR, Dresden, Germany

This talk should give an overview of Superconducting photo injectors (SRF guns) and focus on the present status of SRF gun development, the technical requirements and the critical issues like cavity design, photocathode integration, and emittance compensation methods.

Slides MOZB01 [22.198 MB]

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MOPRO011

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

electron, solenoid, proton, coupling

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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MOPRO013

Present Status of Coherent Electron Cooling Proof-of-Principle Experiment

electron, ion, gun, experiment

87

V. Litvinenko, Z. Altinbas, D.R. Beavis, S.A. Belomestnykh, I. Ben-Zvi, K.A. Brown, J.C. Brutus, A.J. Curcio, L. DeSanto, C. Folz, D.M. Gassner, H. Hahn, Y. Hao, C. Ho, Y. Huang, R.L. Hulsart, M. Ilardo, J.P. Jamilkowski, Y.C. Jing, F.X. Karl, D. Kayran, R. Kellermann, N. Laloudakis, R.F. Lambiase, G.J. Mahler, M. Mapes, W. Meng, R.J. Michnoff, T.A. Miller, M.G. Minty, P. Orfin, A. Pendzick, I. Pinayev, F. Randazzo, T. Rao, J. Reich, T. Roser, J. Sandberg, T. Seda, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, L. Snydstrup, A.N. Steszyn, R. Than, C. Theisen, R.J. Todd, J.E. Tuozzolo, E. Wang, G. Wang, D. Weiss, M. Wilinski, T. Xin, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
G.I. Bell, J.R. Cary, K. Paul, I.V. Pogorelov, B.T. Schwartz, A.V. Sobol, S.D. Webb
Tech-X, Boulder, Colorado, USA
C.H. Boulware, T.L. Grimm, R. Jecks, N. Miller
Niowave, Inc., Lansing, Michigan, USA
A. Elizarov
SUNY SB, Stony Brook, New York, USA
M.A. Kholopov, P. Vobly
BINP SB RAS, Novosibirsk, Russia
P.A. McIntosh, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Work supported by Stony Brook University and by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Coherent Electron Cooling Proof of Principle (CeC PoP) system is being installed in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. It will demonstrate the ability of relativistic electrons to cool a single bunch of heavy ions in RHIC. This technique may increase the beam luminosity by as much as tenfold. Within the scope of this experiment, a 112 MHz 2 MeV Superconducting Radio Frequency (SRF) electron gun coupled with a cathode stalk mechanism, two normal conducting 500 MHz single-cell bunching cavities, a 704 MHz 20 MeV 5-cell SRF cavity and a helical undulator will be used. In this paper, we provide an overview of the engineering design for this project, test results and discuss project status and plansd.

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MOPRO069

Progress Status of the Iranian Light Source Facility Laboratory

booster, storage-ring, synchrotron, dipole

240

J. Rahighi, E. Ahmadi, H. Ajam, M. Akbari, S. Amiri, J. Dehghani, R. Eghbali, S. Fatehi, M. Fereidani, A. Gholampour, A. Iraji, M. Jafarzadeh, B. Kamkari, S. Kashani, P. Khodadoost, H. Khosroabadi, M. Lamehi, M. Moradi, H. Oveisi, S. Pirani, M. Rahimi, N. Ranjbar, R. Rasoli, M. Razazian, A. Sadeghipanah, F. Saeidi, R. Safian, E. Salimi, Kh.S. Sarhadi, O. Seify, M.Sh. Shafiee, A. Shahveh, Z. Shahveh, A. Shahverdi, D. Shirangi, E.H. Yousefi
ILSF, Tehran, Iran
D. Einfeld
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
H. Ghasem
IPM, Tehran, Iran

The Iranian Light Source Facility Project (ILSF) is a 3 GeV third generation light source with a current of 400 mA which will be built on a land of 50 hectares area in the city of Qazvin, located 150 km West of Tehran. ILSF conceptual design report, CDR, was published in October 2012. To have a competitive leading position in the future, 489.6 m storage ring of ILSF is designed to emphasize on small emittance electron beam( 0.93 nm-rad), high photon flux density, brightness, stability and reliability. Moreover, 40% of 489.6 m ring circumference is straight sections (14×8 m+ 14×6 m) which are long enough for the commonly used insertion devices. Some prototype accelerator components such as high power solid state radio frequency amplifiers, LLRF system, thermionic RF gun, Storage ring H-type dipole and quadruple magnets, Hall probe system for magnetic measurement and highly stable magnet power supplies have been constructed in ILSF R&D laboratory.

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MOPRO091

Fundamental Limits of Velocity Bunching of High-brightness Electron Beams

bunching, electron, emittance, gun

304

A. Opanasenko, V.V. Mytrochenko
NSC/KIPT, Kharkov, Ukraine
V.A. Goryashko, V. Zhaunerchyk
Uppsala University, Uppsala, Sweden
P.M. Salen
FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden

The interest in superradiant THz sources based on the coherent transition, synchrotron or undulator radiation grows continuously and such sources require high-quality electron bunches with low emittance, high charge and sub-picosecond (sub-ps) duration. Since accelerator-based THz sources are usually driven by relatively low energy electron bunches of a few tens of MeV, space-charge makes bunch compression to sub-ps level very challenging. In the present work we investigate the feasibility of ballistic bunching down to sub-ps duration while preserving the transverse phase-space quality. We found that in order to compensate for the nonlinear dependency of the arrival time on the energy as well as bunch deformations induced by space-charge effects, one needs to apply a nonlinear energy chirp. This chirp permits to maximize the bunch compression and can be realized by exciting a cavity with higher harmonics of the fundamental frequency. Issues related to synchronizing the harmonics are discussed and the analytical analysis is complemented by simulations with PARMELA.

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MOPRO106

Status of the HZB ERL Prototype BERLinPro

gun, linac, SRF, booster

340

M. Abo-Bakr, W. Anders, R. Barday, K.B. Bürkmann-Gehrlein, A. Burrill, V. Dürr, A. Jankowiak, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, O. Kugeler, B.C. Kuske, A.N. Matveenko, A. Meseck, A. Neumann, K. Ott, E. Panofski, D. Pflückhahn, J. Rahn, J. Rudolph, M. Schmeißer, S.G. Schubert, O. Schüler, J. Völker, S. Wesch
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association.
The Berlin Energy Recovery Linac Prototype BERLinPro is to be constructed at the Helmholtz Zentrum site in Berlin. The aim of the project is to expand the required accelerator physics and technology knowledge mandatory for the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. Since the funding decision in October 2010 the project has entered a phase of detailed planning. Hardware specifications have been defined and various components have been ordered. Furthermore, extensive tests of principal superconducting accelerator components successfully demonstrated the envisaged hardware performance. A summary of the most recent activities together with the details of the project timeline for the coming years are given in this paper.

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MOPRO109

Beam Loss Studies for the KEK Compact-ERL

scattering, simulation, electron, beam-losses

349

O. Tanaka, T. Furuya, K. Harada, N. Nakamura, H. Sakai, M. Shimada, K. Umemori
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan

Beam losses due to eﬀects of Touschek, residual gas, intra-beam scattering, and field emission were studied for the KEK compact Energy Recovery Linac (cERL), which is now under commissioning. By studying the beam losses of cERL, we can better understand the loss mechanisms, estimate the beam loss rates, and localize potentially dangerous areas of the beamline for the future 3GeV ERL project. The goal is to achieve a safety low-emittance and high-current beams operation which can help contribute to the beam loss study under 3GeV ERL project. We used existing and modiﬁed ELEGANT routine to perform the simulations. We also developed a MATLAB data analysis algorithm to handle the large amount of information that is outputted from the program. The data obtained then compared with the theoretical estimation to judge the computation’s accuracy.

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MOPRO112

Energy Recovering for Linac RF Injectors

gun, SRF, HOM, linac

356

V. Volkov, Ya.V. Getmanov, O.A. Shevchenko, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia
A.N. Matveenko
HZB, Berlin, Germany

The article presents a new design of a CW RF high average current superconducting injector cavity. This design allows recovering energy in the injector, improving beam parameters and energy efficiency, reducing injector size, cost, and avoiding high average power coupler problem.

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MOPRO113

Beam-based HOM Measurements in Cornell's ERL Main Linac Cavity

HOM, dipole, quadrupole, linac

359

D.L. Hall, A.C. Bartnik, M.G. Billing, D. Gonnella, G.H. Hoffstaetter, M. Liepe, C.E. Mayes
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

A search for HOMs in Cornell’s ERL main linac cavity installed in a Horizontal Test Cryomodule (HTC) has been carried out using a bunch charge modulation method, as part of the effort towards building an Energy Recovery Linac (ERL). The beam-based HOM measurements offer the significant advantage of being able to detect trapped modes invisible to both the RF pickup probes and HOM damping loads, and allow for measuring the R/Q of the modes. For each HOM detected during the search, measurements were taken to determine its nature (monopole, dipole, etc.), frequency, loaded quality factor and shunt impedance. A selection of the most notable modes found is presented, compared to 3D HOM simulations, and their potential impact on the BBU current of the future Cornell ERL is discussed.

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MOPME009

Numerical Calculation of Electromagnetic Fields in Acceleration Cavities under Precise Consideration of Coupler Structures

dipole, electromagnetic-fields, HOM, impedance

394

C. Liu, W.A. Ackermann2, W.F.O. Müller, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Work supported by BMBF under contract 05H12RD5
During the design phase of superconducting radio frequency (RF) accelerating cavities a challenging and difficult task is to determine the electromagnetic field distribution inside the structure with the help of proper computer simulations. Although dissipation due to lossy materials is neglected in the current work, in reality, because energy transfer appears due to the design of the superconducting cavities, the numerical eigenmode analysis based on real-valued variables is no longer suitable to describe the dissipative acceleration structure. Dissipation can appear with the help of dedicated higher order mode (HOM) couplers, the power coupler as well as the beam tube once the resonance frequency is above the cutoff frequency of the corresponding waveguide. At the Computational Electromagnetics Laboratory (TEMF) a robust parallel eigenmode solver based on complex-valued finite element analysis is available. The eigenmode solver has been applied to the TESLA 1.3 GHz and the third harmonic 3.9 GHz nine-cell cavities to determine the resonance frequency, the quality factor and the corresponding field distribution of eigenmodes.

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MOPME014

Automated Mode Recognition Algorithm for Accelerating Cavities

coupling, 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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MOPME017

Study of Higher Order Modes in Multi-Cell Cavities for BESSY-VSR Upgrade

HOM, SRF, dipole, linac

412

T. Galek, K. Brackebusch, Sh. Gorgi Zadeh, 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.
BESSY-VSR is a planned scheme to upgrade the existing BESSY II storage ring to support variable electron pulse lengths. In addition to the present 0.5 GHz energy replenishment cavity, two additional SRF bunch compressing cavities operating at 1.5 GHz (3rd harmonic) and 1.75 GHz (sub-harmonic), will be installed. These cavities are essential to produce short 1.5 ps bunches with current of up to 0.8 mA per bunch. In order to achieve such high beam currents, higher order modes must be damped in the superconducting cavities. In this work we present analysis of higher order modes in cavities with different mid-cell shapes.

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MOPME018

Quantification of Geometric Uncertainties in Single Cell Cavities for BESSY VSR using Polynomial Chaos

simulation, HOM, linac, SRF

415

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

Funding: Federal Ministry for Research and Education Germany under contract 05K13HR1
The electromagnetic properties of SRF cavities are mostly determined by their shape. Due to fabrication tolerances, tuning and limited resolution of measurement systems, the exact shape remains uncertain. In order to make assessments for the real life behaviour it is important to quantify how these geometrical uncertainties propagate through the mathematical system and influence certain electromagnetic properties, like the resonant frequencies of the structure's eigenmodes. This can be done by using non-intrusive straightforward methods like Monte-Carlo (MC) simulations. However, such simulations require a large number of deterministic problem solutions to obtain a sufficient accuracy. In order to avoid this scaling behaviour, the so-called polynomial chaos (PC) expansion is used. This technique allows for the relatively fast computation of uncertainty propagation for few uncertain parameters in the case of computationally expensive deterministic models. In this paper we use the PC expansion to quantify the propagation of uncertain geometry on the example of single cell cavities used for BESSY VSR as well as to compare the obtained results with the MC simulation.

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MOPME043

Modeling and Simulation of Beam-induced Plasma in Muon Cooling Devices

plasma, simulation, electron, ion

466

K. Yu
SBU, Stony Brook, USA
M. Chung, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
V. Samulyak
BNL, Upton, Long Island, New York, USA
V. Samulyak
SUNY SB, Stony Brook, New York, USA

Understanding of the interaction of muon beams with plasma in muon cooling devices is important for the optimization of the muon cooling process. We have developed numerical algorithms and parallel software for self-consistent simulation of the plasma production and its interaction with particle beams and external fields. Simulations support the experimental program on the hydrogen gas filled RF cavities in the Mucool Test Area (MTA) at Fermilab. Computational algorithms are based on the electromagnetic particle-in-cell (PIC) code SPACE combined with a probabilistic, macroparticle-based implementation of atomic physics processes such as the absorption of the incident particles, ionization of the absorber material, and the generation and evolution of secondary particles in dense, neutral gas. In particular, we have proposed a novel algorithm for dealing with repetitive incident beam, enabling simulations of long time scale processes. Benchmarks and simulations of the experiments on gas-filled RF cavities and prediction for future experiments are discussed.
* kwangmin.yu@stonybrook.edu
** rosamu@bnl.gov

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MOPRI025

Recent Improvement of Cs2Te Photocathodes at HZDR

cathode, gun, vacuum, SRF

642

R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate
HZDR, Dresden, Germany

Funding: Work supported by the European Community-Research Infrastructure Activity (EuCARD, contract number 227579), and the support of the German Federal Ministry of Education and Research grant 05 ES4BR1/8.
The SRF gun has been successfully operated for the radiation source ELBE at HZDR. To achieve higher current and lower beam emittance, a new niobium cavity with superconducting solenoid and a new 13 MHz laser have been recently developed. For this reason, better photocathodes with high quantum efficiency are urgently in demand. In this work we improve the present Cs2Te preparation system for cleaner environment and more precise stoichiometric control than before. A new mask is designed to prevent cesium pollution of the cathode body. Instead of Kapton only alumina ceramics are used for isolation, and the cathode plugs are degassed at higher temperature. New evaporators are installed and tested to obtain an accurate deposition rate. Furthermore, the cathode transfer system is thoroughly cleaned for a better vacuum condition.

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MOPRI027

Dark Current Studies at Relativistic Electron Gun for Atomic Exploration – REGAE

electron, gun, vacuum, operation

649

H. Delsim-Hashemi, K. Flöttmann
DESY, Hamburg, Germany

Electron diffraction is a tool for exploring structural dynamics of matter. The scattering cross section is orders of magnitude higher for electrons than for X-rays so that only a small number of electrons is required to achieve comparable results. However, the required electron beam quality is extraordinary. To study e. g. proteins a coherence length of 30 nm is required which translates into a transverse emittance of 5 nm at a spot size of 0.4mm. In addition short bunch lengths down to 10 fs and a temporal stability of the same order are required in order to study chemical reactions or phase transitions in pump probe type experiments. These are challenging parameters for an electron source, which demand improvements at many frontiers. Dark current degrades contrast of diffraction patterns in all experiments. Understanding dark-current generation and propagation can lead to better methods to decrease it. In this paper dark current studies that are performed at REGAE will be presented.

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MOPRI030

Basic Design of a 20K C-band 2.6-cell Photocathode RF Gun

gun, simulation, electron, vacuum

658

T. Tanaka, M. Inagaki, K. Nakao, K. Nogami, T. Sakai
LEBRA, Funabashi, Japan
M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida
KEK, Ibaraki, Japan
T.S. Shintomi
Nihon University, Tokyo, Japan

Funding: This research was supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
A cryocooled C-band photocathode RF gun operating at 20K is under design at Nihon University. The RF gun is of BNL-type 2.6-cell pillbox cavity with a resonant frequency of 5712 MHz. With high-purity Oxygen-free copper used as the cavity material, the quality factor of the cavity is expected to be approximately 60000 from theoretical prediction of the anomalous skin effect at low temperatures. Considering the cooling capacity, initial operation of the RF gun is assumed at a duty factor of 0.01%. The cavity elements designed for low-power test is in preparation for machining. The low-power test at room temperature is scheduled early spring in 2014 before assembled at KEK by means of diffusion bonding technique. Since it is intended for the basic understanding and measurements of low temperature RF properties, the cavity is not equipped with structures for the photocathode assembling or the RF input coupler. The cavity design and the results of RF properties measured at room temperature before diffusion bonding will be reported.

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MOPRI033

Quasi-traveling Wave Side Couple RF Gun Commissioning for SuperKEKB

gun, emittance, cathode, coupling

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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MOPRI034

Development of temporal response measurement system for transmission-type spin-polarized photocathodes

electron, laser, resonance, linear-collider

670

T. Inagaki, M. Hosaka, Y. Takashima, N. Yamamoto
Nagoya University, Nagoya, Japan
M. Adachi
KEK, Ibaraki, Japan
X.G. Jin
Institute for Advanced Research, Nagoya, Japan
M. Katoh, T. Konomi
UVSOR, Okazaki, Japan
Y. Okano
IMS, Okazaki, Japan

Spin polarized electron beam is essential for "International Linear Collider". In Nagoya University, transmission-type spin-polarized photocathodes have been developed, and the quantum efficiency of 0.5 % and the polarization of 90 % were achieved*,**. Recently, we succeeded in making the active layer several times thicker with keeping the spin polarization on the GaAs/GaAsP strain-compensated superlattice photocathode***. Increasing the thickness of the active layer is very advantageous for high quantum efficiency, but might be disadvantageous for pulse response. In order to investigate the pulse response, we have developed a pulse length measurement system by using an RF deflecting cavity. In the measurement, magnetic field induced on the beam axis kicks electron pulse transversely and the pulse length is projected to the transverse plane, which is measured by knife-edge method. The pump laser pulses are provided by a Ti:sapphire laser oscillator. By using a pulse stretcher, the pulse width of the pump laser can be changed in the range between 130 fs and 20 ps. In the poster session, we will describe the details of the measurement system and the most recent experimental results.
* T. Nakanishi, The XXI International LINAC Conference(1998)
** Xiuguang Jin, Japanese Journal of Applied Physics 51 (2012) 108004
*** Xiuguang Jin, Applied Physics Express 6 (2013) 015801

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MOPRI035

Development of the Photocathode LiTi2O4 and Evaluations of the Initial Emittance

cathode, laser, electron, emittance

673

R. Inagaki, M. Hosaka, Y. Takashima, N. Yamamoto
Nagoya University, Nagoya, Japan
T. Hitosugi, S. Shiraki
Tohoku Uneversity, WPI-AIMR, Sendai, Japan
E. Kako, Y. Kobayashi, S. Yamaguchi
KEK, Ibaraki, Japan
M. Katoh, T. Konomi, T. Tokushi
UVSOR, Okazaki, Japan
Y. Okano
IMS, Okazaki, Japan

In UVSOR, the X-ray free electron laser (XFEL) based on linear accelerator with high pulse repetition about 1MHz has been designed as a candidate for the next radiation sources. We thought a combination of superconducting RF cavity and photocathode is an optimal electron gun for the new accelerator. For this electron gun, we propose a back-illuminated multi-alkali* photocathode with transparent superconductor LiTi2O4**. The reason for using LiTi2O4 is to reflect RF by using feature of penetration depth of superconductor, which is defined from London equation. This feature protects optical components from RF damage. However, LiTi2O4 is a new material and properties are not clear. We have measured the basic properties of this photocathode, such as magnetic susceptibility measurement and photoelectron spectrometry, etc. In this conference, we will explain the detail of the concept and advantage of this cathode, and show the result measured about the basic properties of this photocathode focusing on the initial emittance measurement.
* A. V. Lyashenko et al. JINST 4 P07005 (2009)
** Kumatani et al. APL 101 (2012) 123103″

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MOPRI039

Ultra-short Electron Bunch Generation using Energy-chirping Cell Attached RF Electron Gun

gun, electron, simulation, radiation

685

K. Sakaue, Y. Koshiba, M. Mizugaki, M. Washio
Waseda University, Tokyo, Japan
R. Kuroda
AIST, Tsukuba, Ibaraki, Japan
T. Takatomi, J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported by JSPS Grant-in-Aid for Young Scientists (B) 23740203 and Scientific Research (A) 10001690
We have been developing an Energy-Chirping-Cell attached RF electron gun (ECC-RF-Gun) for generating ultra-short electron bunches. ECC-RF-Gun has extra cell at the end of gun cavity in order to chirp the bunch energy. Such a bunch can be compressed by the velocity difference though the drift space. We have already installed it to our accelerator system and successfully observed a coherent synchrotron/transition radiation at 0.3THz. It is clear that the bunch length was short enough to generate 0.3THz, which corresponds to less than 500fs bunch length was achieved if we assume the gaussian shape. In this conference, the principle of ECC-RF-Gun, the recent results of bunch length measurement and future prospective will be presented.

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MOPRI054

Status of the APEX Project at LBNL

gun, cathode, FEL, linac

727

F. Sannibale, K.M. Baptiste, C.W. Cork, J.N. Corlett, S. De Santis, L.R. Doolittle, J.A. Doyle, D. Filippetto, G.L. Harris, G. Huang, H. Huang, R. Huang, T.D. Kramasz, S. Kwiatkowski, R.E. Lellinger, V. Moroz, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, H.J. Qian, J.W. Staples, M. Vinco, S.P. Virostek, R.P. Wells, M.S. Zolotorev
LBNL, Berkeley, California, USA
R. Huang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL), consists in the development of an injector designed to demonstrate the capability of the VHF gun, a normal conducting 186 MHz RF gun operating in CW mode, to deliver the brightness required by X-ray FEL applications at MHz repetition rate. APEX is organized in 3 main phases where different aspects of the required performance are gradually demonstrated. The status and future plans for the project are presented.

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MOPRI056

Design and Fabrication of a VHF - CW High Repetition Rate Electron Gun

cathode, gun, vacuum, operation

733

R.P. Wells, B. Ghiorso, F. Sannibale, J.W. Staples
LBNL, Berkeley, California, USA
T.M. Huang
IHEP, Beijing, People's Republic of China

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
A high repetition rate, MHz, electron source is a key element in future FEL based light sources. The Advance Photo-injector Experiment (APEX) at Lawrence Berkeley National Laboratory (LBNL) consists of a high repetition rate 186 MHz (VHF-band) CW electron gun, 1 MHz UV laser source and the diagnostic components necessary to quantify the gun’s performance. The gun design is based on well established, conventional RF cavity design, with a couple notable exceptions. The basis for the selection of this technology, novel design features, fabrication techniques and measured cavity performance are presented.

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MOPRI064

First Test Results from SRF Photoinjector for the R&D ERL at BNL

gun, SRF, cathode, electron

748

D. Kayran, Z. Altinbas, D.R. Beavis, S.A. Belomestnykh, I. Ben-Zvi, J. Dai, S. Deonarine, D.M. Gassner, R.C. Gupta, H. Hahn, L.R. Hammons, C. Ho, J.P. Jamilkowski, P. Kankiya, N. Laloudakis, R.F. Lambiase, V. Litvinenko, G.J. Mahler, L. Masi, G.T. McIntyre, T.A. Miller, D. Phillips, V. Ptitsyn, T. Rao, T. Seda, B. Sheehy, K.S. Smith, A.N. Steszyn, T.N. Tallerico, R. Than, R.J. Todd, E. Wang, D. Weiss, M. Wilinski, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi, J. Dai, L.R. Hammons, V. Litvinenko, V. Ptitsyn
Stony Brook University, Stony Brook, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE and DOE grant at Stony Brook, DE-SC0005713.
An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is presently under commissioning at Brookhaven National Laboratory (BNL). This facility enables testing of concepts relevant for high-energy coherent electron cooling, electron-ion colliders, and high repetition rate Free-Electron Lasers. The ERL will be capable of providing electron beams with sufficient quality to produce high repetition rate THz and X-ray radiation. When completed the SRF photoinjector will provide 2 MeV energy and 300 mA average beam current. The injector for the R&D ERL was installed in 2012, this includes a 704MHz SRF gun* with multi-alkali photocathode, cryo-system upgrade and a novel emittance preservation zigzag-like low energy merger system. We describe the design and major components of the R&D ERL injector then report the first experimental results and experiences learned in the first stage of beam commissioning of the BNL R&D ERL.
* Wencan Xu et al., “Commissioning SRF gun for the R&D ERL at BNL”, IPAC2013 proceedings, WEPWO085.

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MOPRI072

Simulation Study of Heavy Ion Beam Injection and Acceleration in the HESR for Internal Target Experiments with Cooling

target, ion, experiment, acceleration

768

H. Stockhorst, B. Lorentz, R. Maier, D. Prasuhn, R. Stassen
FZJ, Jülich, Germany
T. Katayama
Nihon University, Narashino, Chiba, Japan

Recently, the feature of ion beam injection, storage and acceleration assisted by a barrier bucket and cooling has been investigated in the High Energy Storage Ring HESR at the new facility FAIR which will be built at the GSI Darmstadt. A bare uranium beam is injected from the collector ring CR into the HESR at 740 MeV/u*. The simulation studies are now improved to include different injection schemes applying either the barrier cavity or the h = 1 cavity in the HESR. It is outlined how the new 2.5 MeV electron cooler at COSY Jülich or stochastic cooling can support the injection mechanism. The beam preparation for an internal target experiment with cooling is outlined. The acceleration of the ion beam is extended to 5 GeV/u under the mandatory condition of the available cavity voltages and the maximum magnetic field ramp rate in the HESR. The flexibility of the HESR ring lattice is utilized to avoid transition energy crossing during ramping up to 5 GeV/u and to adjust the rings’ frequency slip factor for optimal stochastic cooling. The cooling simulations include the beam-target interaction due to a hydrogen target.
* H. Stockhorst et al., MOPEA018, IPAC13

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MOPRI093

Technical Design of Normal Conducting Re-buncher in the MEBT for Rare Isotope Science Project

rfq, acceleration, ion, operation

830

H.J. Kim, W.K. Han, I.S. Hong, D. Jeon
IBS, Daejeon, Republic of Korea

Funding: This work was supported by the RISP of Institute for Basic Science funded by Ministry of Science, ICT and Future Planning and National Research Foundation of Korea.(2011-0032011)
The front-end system of RISP heavy-ion accelerator(RAON) consists of an electron cyclotron resonance ion source, a low energy beam transport line, a radio frequency quadrupole accelerator and a medium energy beam transport(MEBT) line. The MEBT system, which consists of quadrupole magnets, three normal-conducting re-bunchers and diagnostic devices, is installed between the RFQ accelerator and the superconducting linac(SCL). The three normal-conducting re-bunchers are used to minimize the growths of the longitudinal emittance and to manipulate the particle distribution on longitudinal phase space for beam transportation in SCL. Several combination of the number of cavities was examined, and the quarter wave resonator(QWR) type re-buncher was chosen for MEBT line in RAON. The QWR cavity has a frequency of 81.25 MHz, a maximum electric field of 2.53 MV/m on the cavity surface with an electric field of 1 MV/m on the beam axis, a geometrical beta factor of 0.032 and an effective length of 24 cm. In this presentation, I will present the results of baseline design for electro-magnetic field analysis and mechanical design for stress analysis, thermal stress analysis and cooling channel.

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MOPRI103

Longitudinal Bunch Shortening for the Laser Stripping Project

laser, focusing, linac, acceleration

861

T.V. Gorlov, A.V. Aleksandrov, S.M. Cousineau, V.V. Danilov, Y. Liu, M.A. Plum
ORNL, Oak Ridge, Tennessee, USA

Funding: This work is funded by the U.S. DOE under grant number DE-FG02-13ER41967, and by the U.S. DOE under contract number DE-AC05-00OR22725 with UT-Battelle Corporation.
Realization of high efficiency laser stripping at the SNS accelerator needs good longitudinal overlap between H⁻ bunch and laser pulse. The default H⁻ bunch length at the interaction point is 5 times bigger than needed in order to achieve 90% stripping efficiency. Theoretical and experimental studies of longitudinal H⁻ bunch shortening are presented in this paper.

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TUOBA02

Design Study of an ERL Test Facility at CERN

electron, cryomodule, linac, optics

921

E. Jensen, C. Bracco, O.S. Brüning, R. Calaga, N. Catalán Lasheras, B. Goddard, R. Torres-Sanchez, A. Valloni
CERN, Geneva, Switzerland
M. Klein
The University of Liverpool, Liverpool, United Kingdom

The modern concept of an Energy Recovery Linac allows providing large electron currents at large beam energy with low power consumption. This concept is used in FEL’s, electron-ion colliders and electron coolers. CERN has started a Design Study of an ERL Test Facility with the purpose of 1) studying the ERL principle, its specific beam dynamics and operational issues, as relevant for LHeC, 2) providing a test bed for superconducting cavity modules, cryogenics and integration, 3) studying beam induced quenches in superconducting magnets and protection methods, 4) providing test beams for detector R&D and other applications. It will be complementary to existing or planned facilities and is fostering international collaboration. The operating frequency of 802 MHz was chosen for performance and for optimum synergy with SPS and LHC; the design of the cryomodule has started. The ERL Test Facility can be constructed in stages from initially 150 MeV to ultimately 1 GeV in 3 passes, with beam currents of up to 80 mA. Parameters to serve the above-mentioned purposes are well defined and possible lattice designs have well advanced.

Slides TUOBA02 [14.419 MB]

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TUZA01

Advanced Concepts and Challenges in Compton Radiation Sources

laser, electron, plasma, photon

928

I. Pogorelsky
BNL, Upton, Long Island, New York, USA

Ongoing developments in Compton radiation sources are aimed toward a diversity of potential applications, ranging from university-scale compact x-ray light sources and metrology tools for EUV lithography, to positron sources for e⁻e⁺ colliders. Novel conceptual approaches are pursued on different routes: One research direction lies in multiplying the source’s repetition rate and increasing its average brightness by placing the point of Compton interaction inside an optical cavity. High-gradient plasma-wakefield accelerators are fast becoming a practical reality, offering a new paradigm to compact all-optical Compton sources operating in x-ray- and gamma-regions. Continuing improvement in the quality of the beam of plasma accelerators promises the achievement of fully coherent Compton x-rays, thereby prompting the evolution of the Compton source to an all-optical free-electron laser.

Slides TUZA01 [22.419 MB]

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TUXB01

Recent Progress in 3D Numerical Wakefield Calculations

impedance, electron, insertion, damping

944

W. Bruns
WBFB, Berlin, Germany

The 3D electromagnetic Field Simulator GdfidL computes Wakepotentials on standard CPUs with a Speed comparable to GPU-Based Implementations. This is achieved via Computing only in interesting Cells, having the FD-Coefficients in compressed Form, traversing the Grid in a Cache-friendly Order and applying a blocked Update Scheme which is NuMA-aware. A Dispersion optimised Scheme is described. Fields in dispersive Materials are computed via solving the Equations of the Electron Hulls of the Material. Moving Mesh Computations have the Grid-generation on the Fly.

Slides TUXB01 [16.169 MB]

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TUOAB01

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

factory, HOM, coupling, 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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TUPRO001

Alternative High Luminosity LHC Matching Section Layout

optics, injection, quadrupole, luminosity

990

B. Dalena, A. Chancé
CEA/IRFU, Gif-sur-Yvette, France
R. De Maria
CERN, Geneva, Switzerland
J. Payet
CEA/DSM/IRFU, France

Funding: The research leading to these results has received funding from the European Commission under the FP7 project HiLumi LHC, GA no. 284404, co-funded by the DoE, USA and KEK, Japan.
In the framework of the HL-LHC Upgrade project possible variants for the layout of the LHC matching section located in the high luminosity insertions are investigated. This layout is optimized to reduce the demand on the voltage of the crab cavities, it also improves the optics squeeze-ability, both in ATS[1] and non-ATS mode. Moreover the injection and transitions to collision optics are also discussed. [1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

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TUPRO006

Strong-strong Beam-beam Simulation for the LHC Upgrade

emittance, simulation, resonance, luminosity

1006

J. Qiang, S. Paret
LBNL, Berkeley, California, USA
G. Arduini, T. Pieloni
CERN, Geneva, Switzerland
J. Barranco García
EPFL, Lausanne, Switzerland

Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 using computing resources at the NERSC.
The LHC upgrade will significantly improve the performance of the current LHC operation with higher collision energy and luminosity. In the paper, we report on the progress in the strong-strong beam-beam simulation of the HL-LHC upgrade with crab cavity compensation. We will present the study of the effects of accelerator tune working points, dipole noise, and crab cavity noise on colliding beam emittance growth.

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TUPRO013

Studies on Stochastic Cooling of Heavy Ions in the LHC

kicker, luminosity, ion, pick-up

1030

M. Schaumann, J.M. Jowett, B. Salvant, M. Wendt
CERN, Geneva, Switzerland
M. Blaskiewicz, S. Verdú-Andrés
BNL, Upton, Long Island, New York, USA

Future high luminosity heavy-ion operation of the LHC will be dominated by very rapid luminosity decay due to the large collision cross-section and, to a lesser extent, emittance growth from intra-beam scattering (IBS) due to the high bunch intensities. A stochastic cooling system could reduce the emittance far below its initial value and reduce the losses from debunching during collisions, allowing more of the initial beam intensity to be converted into integrated luminosity before the beams are dumped. We review the status of this proposal, system and hardware properties and potential locations for the equipment in the tunnel.

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TUPRO016

Machine Protection Challenges for HL-LHC

extraction, beam-losses, operation, luminosity

1039

R. Schmidt, T. Bär, J. Wenninger, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland

LHC operation requires the flawless functioning of the machine protection systems. The energy stored in the beam was progressively increased beyond the 140 MJ range at the end of 2012 at 4 TeV/c. The further increase to 364 MJ expected for 2015 at 6.5 TeV/c should be possible with the existing protection systems. For HL-LHC, additional failure modes are considered. The stored beam energy will increase by another factor of two with respect to nominal and a factor of five more than experienced so far. The maximum beta function will increase. It is planned to install crab cavities in the LHC. With crab cavities, sudden voltage decays within 100 us after e.g. cavity quenches lead to large beam oscillations. Tracking simulations predict trajectory distortions of up to 1.5 σ in the first turn after a sudden drop of the deflecting voltage in a single cavity within 3 turns. The energy of several MJ stored in halo protons that could hit the collimator in case of such events is far above damage level, even if the collimator jaws are made of robust material. In this paper we discuss the challenges for machine protection in the HL-LHC era and possible mitigation strategies.

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TUPRO017

HL-LHC Performance with a 200 MHz RF System

luminosity, impedance, electron, simulation

1043

R. Tomás, C.O. Domínguez
CERN, Geneva, Switzerland
S.M. White
BNL, Upton, Long Island, New York, USA

The HL-LHC performance could considerably benefit from having a 200 MHz RF system. This would allow to inject longer bunches with larger bunch intensity from the SPS and to perform bunch length leveling if required. We also consider the possibility of decreasing the crab cavity frequency to increase both virtual peak luminosity and luminous region. Performance estimates of various configurations are presented in this paper.

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TUPRO021

Preliminary Study of Risks and Failure Scenarios for the High Luminosity Experiments in HL-LHC

luminosity, simulation, detector, experiment

1055

F. Bouly
LPSC, Grenoble Cedex, France
R. Alemany-Fernández, H. Burkhardt, D. Wollmann
CERN, Geneva, Switzerland
B. Yee-Rendón
CINVESTAV, Mexico City, Mexico

For the HL-LHC it is planned to basically double the diameter of the triplet quadruple magnets around the high luminosity insertions of the LHC. The high luminosity experiments ATLAS and CMS would like to keep a small central chamber radius close the interaction point. In the context of collider-experiment studies for the high-luminosity upgrade of the LHC, we present a first study of the possible consequences of these changes for the experimental running conditions based on detailed simulations with tracking. We have started to implement crab cavity failures and discuss first results from these simulations.

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TUPRO032

RHIC Performance for FY2014 Heavy Ion Run

luminosity, electron, kicker, ion

1090

G. Robert-Demolaize, J.G. Alessi, M. Bai, E.N. Beebe, J. Beebe-Wang, S.A. Belomestnykh, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, R. Connolly, T. D'Ottavio, K.A. Drees, A.V. Fedotov, W. Fischer, C.J. Gardner, D.M. Gassner, X. Gu, M. Harvey, T. Hayes, H. Huang, P.F. Ingrassia, J.P. Jamilkowski, N.A. Kling, J.S. Laster, C. Liu, Y. Luo, D. Maffei, Y. Makdisi, M. Mapes, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, A.I. Pikin, P.H. Pile, V. Ptitsyn, D. Raparia, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, C. Schultheiss, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, J.E. Tuozzolo, B. Van Kuik, M. Wilinski, Q. Wu, A. Zaltsman, K. Zeno, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
After running uranium-uranium and copper-gold collisions in 2012, the high energy heavy ion run of the Relativistic Heavy Ion Collider (RHIC) for Fiscal Year 14 (Run14) is back to gold-gold (Au-Au) collisions at 100 GeV/nucleon. Following the level of performance achieved in Run12, RHIC is still looking to push both instantaneous and integrated luminosity goals. To that end, a new 56 MHz superconducting RF cavity was installed and commissioned, designed to keep ions in one RF bucket and improve luminosity by allowing a smaller beta function at the interaction point (IP) due to a reduced hourglass effect. The following presents an overview of these changes and reviews the performance of the collider.

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TUPRO046

Beamlines with Two Deflecting Cavities for Transverse-to-Longitudinal Phase Space Exchange

quadrupole, beam-transport, emittance, controls

1129

V. Balandin, W. Decking, N. Golubeva
DESY, Hamburg, Germany

Optical systems for transverse-to-longitudinal emittance exchange involving single dipole-mode cavity were in great details studied during the last decade theoretically and experimentally. In this paper we discuss the question, if there are any advantages in usage of beamlines utilizing two deflecting cavities instead of one. The general analysis is presented and specific beamline designs are given as examples.

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TUPRO116

Conceptual Design of the Muon Cooling Channel to Incorporate RF Cavities

solenoid, dipole, quadrupole, controls

1325

S.A. Kahn, G. Flanagan, F. Marhauser
Muons, Inc, Illinois, USA
M.L. Lopes, K. Yonehara
Fermilab, Batavia, Illinois, USA

Funding: Work supported by U.S. DOE STTR/SBIR grant DE-SC00006266
A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoid, helical dipole and helical quadrupole fields has been shown to provide six-dimensional phase space reduction for muon beams. Such a channel can be implemented by a helical solenoid (HS) composed of short solenoid coils arranged in a helical pattern. The magnetic channel will provide the desired Bphi, Bz, and dBphi/dr along the reference path. The channel must allow enough space for RF cavities which replace energy lost in the absorber material present for the cooling process. The study will describe how to achieve the desired field while allowing sufficient space for the cavities. The limits to this design imposed by the achievable current density in the coils will be discussed.

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TUPME008

Status of the CLIC-UK R&D Programme on Design of Key Systems for the Compact Linear Collider

feedback, collider, quadrupole, linear-collider

1354

P. Burrows, R. Ainsworth, T. Aumeyr, D.R. Bett, N. Blaskovic Kraljevic, L.M. Bobb, S.T. Boogert, A. Bosco, G.B. Christian, L. Corner, F.J. Cullinan, M.R. Davis, D. Gamba, P. Karataev, K.O. Kruchinin, A. Lyapin, L.J. Nevay, C. Perry, J. Roberts, J. Snuverink, J.R. Towler
JAI, Oxford, United Kingdom
R. Ainsworth, T. Aumeyr, S.T. Boogert, A. Bosco, P. Karataev, K.O. Kruchinin, L.J. Nevay, J.R. Towler
Royal Holloway, University of London, Surrey, United Kingdom
P.K. Ambattu, G. Burt, A.C. Dexter, M. Jenkins, S. Karimian, C. Lingwood, B.J. Woolley
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
L.M. Bobb, R. Corsini, D. Gamba, A. Grudiev, A. Latina, T. Lefèvre, C. Marrelli, M. Modena, J. Roberts, H. Schmickler, D. Schulte, P.K. Skowroński, J. Snuverink, S. Stapnes, F. Tecker, R. Tomás, R. Wegner, M. Wendt, W. Wuensch
CERN, Geneva, Switzerland
J.A. Clarke, S.P. Jamison, P.A. McIntosh, B.J.A. Shepherd
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
N.A. Collomb, D.G. Stokes
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
L. Corner
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
W.A. Gillespie, R. Pan, M.A. Tyrk, D.A. Walsh
University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
R.M. Jones
UMAN, Manchester, United Kingdom

Six UK institutes are engaged in a collaborative R&D programme with CERN aimed at demonstrating key aspects of technology feasibility for the Compact Linear Collider (CLIC). We give an overview and status of the R&D being done on: 1) Drive-beam components: quadrupole magnets and the beam phase feed-forward prototype. 2) Beam instrumentation: stripline and cavity beam position monitors, an electro-optical longitudinal bunch profile monitor, and laserwire and diffraction and transition radiation monitors for transverse beam-size determination. 3) Beam delivery system and machine-detector interface design, including beam feedback/control systems and crab cavity design and control. 4) RF structure design. In each case, where applicable, we report on the status of prototype systems and performance tests with beam at the CTF3, ATF2 and CesrTA test facilities, including plans for future experiments.

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TUPME009

A Sub-micron Resolution, Wide-band, Stripline BPM System for Driving Bunch-by-bunch Feed-back and Feed-forward Systems at ATF

feedback, kicker, operation, extraction

1358

G.B. Christian, D.R. Bett, N. Blaskovic Kraljevic, P. Burrows, M.R. Davis, Y.I. Kim, C. Perry
JAI, Oxford, United Kingdom

A low-latency, sub-micron resolution stripline beam position monitoring (BPM) system has been developed and tested with beam at the KEK Accelerator Test Facility (ATF2), where it has been used as part of a beam stabilisation system. The fast analogue front-end signal processor is based on a single-stage RF down-mixer and a position resolution below 400 nm has been demonstrated for beam intensities of ~1 nC, with single-pass beam. The BPM position data are digitised by fast ADCs on an FPGA-based digital feedback controller, which is used to drive either a pair of kickers local to the BPMs and nominally orthogonal in phase, in closed-loop feedback mode, or a downstream kicker in the ATF2 final focus region, in feedforward mode. The beam jitter is measured downstream of the final focus system with high resolution, low-Q, cavity BPMs, and the relative performance of both systems in stabilising the beam is compared.

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TUPME011

The Status of the Construction of MICE Step IV

solenoid, experiment, emittance, coupling

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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TUPME014

Development of Six-dimensional Helical Muon Beam Cooling Channel for Muon Colliders

emittance, solenoid, collider, magnet-design

1373

K. Yonehara
Fermilab, Batavia, Illinois, USA

A six-dimensional (6D) helical muon beam cooling channel (HCC) has been developed for a last decade. The practical HCC lattice parameters were optimized for the cooling performance in theoretical and numerical simulations. The HCC design group has been formed and has begun the machine development to realize the channel. Recent accomplishments and present critical issues are discussed in the presentation.

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TUPME023

Overview of a muon capture section for muon accelerators

proton, target, solenoid, bunching

1398

D. Stratakis, J.S. Berg, H. K. Sayed
BNL, Upton, Long Island, New York, USA
D.V. Neuffer, P. Snopok
Fermilab, Batavia, Illinois, USA
P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Work supported by Brookhaven Science Associates, LC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We describe a muon capture section to manipulate the longitudinal and transverse phase-space so that to collect efficiently a muon beam produced from an intense proton source target. We show that this can be achieved by using a set of properly tuned rf cavities that captures the beam into string of bunches and aligns them into nearly equal central energies, and a solenoidal chicane that filters high momentum particles, followed by a proton absorber that reduces the energy of all particles. This work elucidates the key parameters that are needed for successful muon capture, such as the required rf frequencies, rf gradients and focusing field. We discuss the sensitivity in performance against the number of different rf frequencies and accelerating rf gradient.

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TUPME024

A hybrid six-dimensional muon cooling channel with gas filled cavities

emittance, vacuum, lattice, simulation

1401

D. Stratakis
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Obtaining the desired micron-scale emittances for a Muon Collider requires transporting the muon beam through long sections of a beam channel containing rf cavities, absorbers, and focusing solenoids. Here we discuss possible implementation of high-pressure gas-filled RF cavities in a 6D ionization cooling channel and some technical issues associated with it. The key idea of our scheme is a hybrid approach that uses high-pressure gas to avoid cavity breakdown, along with discrete LiH absorbers to provide the majority of the energy loss. We show that the channel performs as well as the original vacuum rf channel while potentially avoiding degradation in rf gradient associated with the strong magnetic field in the cooling channel.

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TUPME030

The LIGHT Beamline at GSI: Shaping Intense MeV Proton Bunches from a Compact Laser-driven Source

proton, laser, focusing, ion

1419

S. Busold, O. Deppert, M. Roth
TU Darmstadt, Darmstadt, Germany
V. Bagnoud, A. Blazevic, S. Busold
HIJ, Jena, Germany
V. Bagnoud, A. Blazevic, S. Busold, D. Schumacher
GSI, Darmstadt, Germany
C. Brabetz
IAP, Frankfurt am Main, Germany
F. Kroll
TU Dresden, Dresden, Germany
F. Kroll
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany

Laser-based proton acceleration as a source of high intensity multi-MeV-range proton bunches became subject of extensive research during the last 15 years and is discussed as potential candidate for various applications. However, their usage often requires special ways of beam shaping first, as the particles are emitted in a wide energy spectrum and with a large divergence angle from the laser matter interaction point. To handle these characteristics, a test stand has been build at GSI Darmstadt, using a pulsed high field solenoid and a radiofrequency cavity to produce intense collimated proton bunches with low energy spread from a TNSA source. In recent experiments, energy compression of an intense proton bunch around 10 MeV central energy to an energy spread of less than 3% could be demonstrated. The particle numbers were in access of 10⁹ protons and the bunch duration was only a few nanoseconds. Even shorter bunches and thus higher particle intensities are possible. This compact laser-driven proton beamline, available now at GSI, will be introduced and latest experimental results presented.

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TUPME053

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

coupling, ion, ion-source, 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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TUPME054

Influence of a Vacuum Gap on a Bunch Wakefield in a Circular Waveguide Filled up with Dielectric

vacuum, wakefield, radiation, electromagnetic-fields

1489

T.Yu. Alekhina, A.V. Tyukhtin, V.V. Vorobev
Saint-Petersburg State University, Saint-Petersburg, Russia

Analysis of electromagnetic field of a particle bunch intersecting several boundaries in a dielectric waveguide is important for the wakefield acceleration technique and other problems of accelerator physics. In previous works we investigated the case of a single boundary in a waveguide*. Now we study the electromagnetic field of the bunch moving in a dielectric circular waveguide and crossing a vacuum cavity. The main attention is given to the case when wakefield (Cherenkov radiation) is generated in dielectric. The behavior of the total field depending on distance and time is explored numerically. Analytical estimations are made as well. Influence of the vacuum gap on the wakefield is considered for different lengths of the gap. It is clarified conditions when the vacuum gap does not practically influence on the wakefield. It is noted that the quasi monochromatic wave (the Cherenkov transition radiation) generated in the vacuum region can be used for restoration of the field in the area after the gap. This effect can be achieved for some optimal parameters of the problem.
* T.Yu. Alekhina, A.V. Tyukhtin, Phys. Rev. ST-AB, v.15, 091302 (2012);
T.Yu. Alekhina, A.V. Tyukhtin, Phys. Rev. ST-AB, v.16, 081301 (2013).

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TUPME057

Optimization of Accelerators and Light Sources within oPAC

network, simulation, controls, booster

1499

C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485.
The optimization of particle accelerators and light sources by combining studies into beam physics, instrumentation, numerical simulations and accelerator control systems is the aim of the EU-funded oPAC project. With a budget of more than 6 M€, oPAC is one of the largest training networks ever funded by the EU and currently trains more than 20 Marie Curie Fellows. This paper presents selected research highlights, including optimization studies into the CERN Proton Synchrotron (PS), measurement and correction of linear and nonlinear optics distortions in the ALBA synchrotron (Spain), perturbation measurements of a cavity Schottky noise detector at GSI (Germany) and R&D into device control data base tool at COSYLAB (Slovenia). Moreover, a summary of past and future oPAC events is also given.

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TUPME059

Longitudinal Bunch Shaping with a Double Dogleg based Emittance Exchange Beam Line

emittance, space-charge, controls, experiment

1506

G. Ha, M.E. Conde, W. Gai, C.-J. Jing, K.-J. Kim, J.G. Power, A. Zholents
ANL, Argonne, Illinois, USA
M.-H. Cho, G. Ha, W. Namkung
POSTECH, Pohang, Kyungbuk, Republic of Korea
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Work supported by High Energy Physics, Office of Science, US DOE.
A new program is under development at Argonne National Laboratory (ANL) to use an emittance exchange (EEX) beamline to produce longitudinally shaped electron bunches. While the ultimate goal is to generate triangular shapes for high transformer ratio wakefield acceleration we are also exploring, in general, the capability of the double dogleg EEX beamline to control the bunch shape. We are studying effects that degrade the quality of the longitudinal current profile including: non-uniform particle distribution, emittance, the deflecting cavity thick-lens effect, 2nd order effects, space charge effects and coherent synchrotron radiation effects. We will present the double dogleg EEX beamline layout and the diagnostic design as well as give a progress report on the experimental status of the program.

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TUPME084

On the Frequency Choice for the eRHIC SRF Linac

linac, SRF, HOM, electron

1547

S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, V. Ptitsyn, W. Xu
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, V. Ptitsyn
Stony Brook University, Stony Brook, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
eRHIC is a future electron-hadron collider proposed at BNL. It will collide high-intensity hadron beams from one of the existing rings of RHIC with a 50-mA electron beam from a multi-pass 10-GeV superconducting RF (SRF) Energy Recovery Linac (ERL). A novel approach to the multi-pass ERL utilizing a non-scaling FFAG was recently proposed. It has many advantages over the previous designs including significant cost savings. The current design has 11 passes in two FFAG rings. To mitigate various beam dynamics effects, it was proposed to lower RF frequency of the SRF linac from 704 MHz used in the previous design. In this paper we consider different effects driving the frequency choice of the SRF ERL and present our arguments for choosing lower RF frequency.

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TUPRI003

Simulating the Production and Eﬀects of Dark Currents in MICE Steps V and VI

electron, solenoid, experiment, simulation

1556

C. Hunt, J. Pasternak, M.A. Uchida
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

Funding: STFC
The completion of the international Muon Ionisation Cooling Experiment (MICE) Step V will involve the construction, commissioning and use of RF cavity and Coupling Coil (RFCC) Modules. The RFCCs consist of 4 RF cavities and a solenoid magnet, and are expected to act as a source of potentially damaging electrons (dark currents) and X-rays. Ongoing work to create a high-statistics simulation of the dark current production, within RF cavities, is described. Current results predict the energy and angular spectra of emitted electrons for an RFCC, and include particle tracking, realistic field maps and ionisation energy losses in cavity windows. Individual electron emitters, parametrised by the Fowler-Nordheim equation, are used and are user-definable, allowing potential worst-case scenarios to be simulated and upper/lower limits for the total dark current to be estimated. These data are being used within the MICE Analysis and User Software (MAUS) to estimate the potential detector backgrounds and the damage that may be inflicted upon the scintillating fibre trackers.

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TUPRI014

Modelling and Long Term Dynamics of Crab Cavities in the LHC

multipole, luminosity, hadron, experiment

1578

R. Appleby, D.R. Brett
UMAN, Manchester, United Kingdom
J. Barranco García, R. De Maria, A. Grudiev, R. Tomás
CERN, Geneva, Switzerland

Funding: The research leading to these results has received funding from the European Commission under the FP7 project HiLumi LHC, GA no. 284404, co-funded by the DoE, USA and KEK, Japan.
The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) aims to achieve an integrated luminosity of 250-300 fb-1 per year. This upgrade includes the use crab cavities to mitigate the geometric loss of luminosity arising from the beam crossing angle. The tight space constraints at the location of the cavities leads to cavity designs which are axially non-symmetric and have a potentially significant effect on the long term dynamics and dynamic aperture of the LHC. In this paper we present the current status of advanced modelling of crab cavities.

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TUPRI015

Transverse Emittance Compensation for the Rossendorf SRF Gun II

gun, solenoid, SRF, electron

1582

H. Vennekate, A. Arnold, P.N. Lu, P. Murcek, J. Teichert, R. Xiang
HZDR, Dresden, Germany
T. Kamps
HZB, Berlin, Germany
P. Kneisel
JLab, Newport News, Virginia, USA

Funding: We acknowledge the support of the EU Community-Research Infrastructure Activity under the FP7 program (EuCARD-2, 312453) and of the German Federal Ministry of Education and Research grant 05K12CR1.
Superconducting RF particle sources combine the advantages of normal conducting RF sources and high duty cycle non-RF sources. The Rossendorf SRF gun was the first to demonstrate this injecting electrons into the ELBE accelerator at 13 MHz. Recently, a new 3-1/2-gun cavity has been prepared at Jefferson Lab for its use in an updated injector which is expected to increase the electron energy from 2.4 to 7.5 MeV. Along with this new cavity, a new gun cryostat has been introduced. It combines several minor updates to the setup with the installation of a superconducting solenoid right at the exit of the gun, compensating the emittance growth of the electron bunch at an early stage. The poster is going to conclude the results of the commissioning of the new cryostat including the solenoid and compare it to the prior concept using a normal conducting solenoid outside the cryostat. As it is of great importance to this subject, studies of the magnetic shielding are going to be presented as well.

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TUPRI021

Impedance Calculation and Simulation of Microwave Instability for the Main Rings of SuperKEKB

impedance, simulation, vacuum, kicker

1600

D. Zhou, T. Abe, T. Ishibashi, Y. Morita, K. Ohmi, K. Shibata, Y. Suetsugu, M. Tobiyama
KEK, Ibaraki, Japan

The SuperKEKB B-factory is now under construction. The designs of the components for the SuperKEKB have mostly been finished. This paper summarises the updated results of longitudinal impedance calculations for various components of the main rings. By summing up all available impedances, a pseudo-Green wake function with bunch length of σ_z=0.5 mm is constructed as an impedance model for consequent studies of collective effects. The results of these studies are also reported in this paper.

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TUPRI023

Simulation of Debunching for Slow Extraction in J-PARC MR

beam-loading, resonance, simulation, impedance

1606

M. Yamamoto, M. Nomura, T. Shimada, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
KEK, Ibaraki, Japan
A. Schnase
GSI, Darmstadt, Germany

The J-PARC MR delivers a proton beam for nuclear physics experiments with slow extraction. The beam is debunched at flat top to obtain a coasting beam by turning off the rf voltage. The controlled emittance blow-up before the flat top has been investigated to mitigate the microwave instability. Beam loading effect can disturb the uniformity of the debunching at the flat top. We describe the results of the particle tracking simulation whole acceleration cycle including the controlled emittance blow-up and the beam loading effect.

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TUPRI043

Analysis of Coupled Bunch Instabilities in BESSY-VSR

HOM, feedback, damping, impedance

1659

M. Ruprecht, P. Goslawski, A. Jankowiak, M. Ries, A. Schälicke, G. Wüstefeld
HZB, Berlin, Germany
T. Weis
DELTA, Dortmund, Germany

BESSY-VSR, a scheme where 1.5 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed*. The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. This paper presents investigations of coupled bunch instabilities driven by HOMs of superconducting multi cell cavities in BESSY-VSR. Analytical calculations and tracking simulations in time domain are performed in the longitudinal and the transverse planes and factors that influence the threshold currents are being discussed. Suitable candidates of cavities which are presently available or in the phase of design are compared with respect to their instability thresholds.
* G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries, Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proceedings of IPAC2011, San Sebastián, Spain

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TUPRI060

Impedance Studies for the PS Finemet® Loaded Longitudinal Damper

impedance, simulation, kicker, synchrotron

1708

S. Persichelli, M. Migliorati, M.M. Paoluzzi, B. Salvant
CERN, Geneva, Switzerland

The impedance of the Finemet® loaded longitudinal damper cavity, installed in the CERN Proton Synchrotron straight section 02 during the Long Shutdown 2013-2014, has been evaluated. Time domain simulations with CST Particle Studio have been performed in order to get the longitudinal and transverse impedance of the device and make a comparison with the longitudinal impedance that was measured for a single cell prototype.

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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, coupling, 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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TUPRI069

NSLS-II Commissioning with 500 MHZ 7-CELL PETRA-III Cavity

storage-ring, feedback, accumulation, synchrotron

1724

A. Blednykh, G. Bassi, W.X. Cheng, J. Choi, Y. Hidaka, S.L. Kramer, Y. Li, B. Podobedov, J. Rose, T.V. Shaftan, G.M. Wang, F.J. Willeke, L.-H. Yu
BNL, Upton, Long Island, New York, USA

The NSLS-II storage ring has been commissioned during Phase 1 with 500 MHz 7-cell PETRA-III RF cavity. In this paper we present our first beam-measured data on instabilities and collective effects with a normal conducting RF system.

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TUPRI070

Analysis of Coupled-bunch Instabilities in the NSLS-II Storage Ring

HOM, impedance, storage-ring, damping

1727

G. Bassi, A. Blednykh, F. Gao, J. Rose
BNL, Upton, Long Island, New York, USA

We discuss coupled-bunch instabilities thresholds for the NSLS-II Storage Ring. In particular, we analyze thresholds from the High Order Modes (HOMs) of the PETRA-III 7-cell cavity. Beam dynamics simulations with the code OASIS, using the measured HOMs, will be compared with machine studies.

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TUPRI073

Impact of Simplified Stationary Cavity Beam Loading on the Longitudinal Feedback System for SIS100

feedback, synchrotron, beam-loading, controls

1736

K. Groß, H. Klingbeil, D.E.M. Lens
TEMF, TU Darmstadt, Darmstadt, Germany
H. Klingbeil
GSI, Darmstadt, Germany
D.E.M. Lens
TU Darmstadt, RTR, Darmstadt, Germany

Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P12RDRBF.
The main synchrotron SIS100 of the Facility for Antiproton and Ion Research (FAIR) will be equipped with a bunch-by-bunch feedback system to damp longitudinal beam oscillations. In the basic layout, one three-tap finite impulse response (FIR) filter will be used for each single bunch and oscillation mode. The detected oscillations are used to generate a correction voltage in dedicated broadband radio frequency (RF) cavities. The digital filter is completely described by two parameters, the feedback gain and the passband center frequency, which have to be defined depending on the longitudinal beam dynamics. In earlier works*, the performance of the closed loop control with such an FIR-filter was analyzed and compared to simulations and measurements with respect to the damping of coherent dipole and quadrupole modes, the first modes of oscillation. This contribution analyzes the influence of cavity beam loading on the closed loop performance and the choice of the feedback gain and passband center frequency to verify future high current operation at FAIR.
* H. Klingbeil et al., IEEE Trans. Nuc. Sci., Vol. 54, No. 6, 2007 and D. Lens et al., Phys. Rev. STAB 16, 032801, 2013.

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TUPRI092

Improvement of the Position Monitor using White Light Interferometer for Measuring Precise Movement of Compact ERL Superconducting Cavities in Cryomodule

target, cryomodule, linac, operation

1787

H. Sakai, K. Enami, T. Furuya, M. Satoh, K. Shinoe, K. Umemori
KEK, Ibaraki, Japan
T. Aoto, K. Hayashi, K. Kanzaki
Tokyo Seimitsu Co. Ltd, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

Alignment of superconducting cavities is one of the important issues for linear collider and/or future light source like ERL and X-FEL. To measure the cavity displacement under cooling to liquid He temperature more precisely, we newly developed the position monitor by using white light interferometer. This monitor is based on the measurement of the interference of light between the measurement target and the reference point. It can measure the position from the outside of the cryomodule. We applied this monitor to the main linac cryomodule of Compact ERL (cERL) and successfully measured the displacement during 2K cooling with the resolution of 10um. However, some drift come from outer temperature and humidity were observed. In this paper, we describe the upgraded version of this monitor to suppress these drift for cERL beam operation.

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TUPRI104

A Beam Arrival Time Cavity for REGAE at DESY

electron, coupling, 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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WEOBA02

Superconducting Linac for Rare Isotope Science Project

linac, cryomodule, ion, proton

1861

H.J. Kim, H.J. Cha, M.O. Hyun, H. Jang, H.C. Jung, Y. Kim, M. Lee, G.-T. Park
IBS, Daejeon, Republic of Korea

Rare Isotope Science Project (RISP) has been proposed as a multi-purpose accelerator facility for providing beams of exotic rare isotopes of various energies. The RISP driver linac which is used to accelerate the beam, for an example, Uranium ions from 0.5 MeV/u to 200 MeV/u consists of superconducting RF cavities and warm quadrupole magnets for focusing heavy ion beams. Requirement of the linac design is especially high for acceleration of multiple charge beams. In this paper, we present the status of RISP linac design and the development of superconducting cavity and cryomodule.

Slides WEOBA02 [9.226 MB]

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WEOCA01

Construction Status of SuperKEKB

dynamic-aperture, controls, detector, damping

1877

N. Ohuchi, K. Akai, H. Koiso
KEK, Ibaraki, Japan

SuperKEKB consists of 7 GeV electron and 4 GeV positron rings (HER and LER), a newly built positron damping ring and an injector linac. The target luminosity is 8x10³⁵ cm^-2s^-1, which is 40 times higher than that achieved at KEKB. Construction of SuperKEKB is progressing on schedule, and beam commissioning is scheduled in 2015. Fabrication, treatment and installation of vacuum components, magnets and power supplies, and beam diagnostic and feedback systems are ongoing. Improvement of RF system and strengthening of cooling system for magnets and beam pipes are also underway. Detailed design of the interaction region has been finalized, and final focus superconducting magnets are under production. The damping ring tunnel and buildings has been completed, and installation of the accelerator components started. The upgrade of the injector linac is also progressing. This paper describes construction status of SuperKEKB main rings and the damping ring as well as recent design progress.

Slides WEOCA01 [6.360 MB]

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WEIB03

How To Produce 100 Superconducting Modules for the European XFEL in Collaboration and with Industry

vacuum, quadrupole, SRF, controls

1923

H. Weise
DESY, Hamburg, Germany

European XFEL accelerator module production is in almost full swing by the time of IPAC 2014. This is the first project of this size that includes many partner laboratories and transfer of technology for mass superconducting RF cavity and accelerator module production to industry. This talk will illustrate the organization of the production and the lessons learned, illuminating what one should or would do differently for future projects.

Slides WEIB03 [11.584 MB]

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WEIB04

Challenges of the XFEL Cryomodule Integration and Industry Transfer

operation, cryomodule, alignment, target

1929

F. Chastel, P. Pluvy, H. Rocipon
ALSYOM, Argebteuil, France

The construction of the European XFEL Accelerator is based on in-kind contributions shared by several institutes throughout Europe and Russia. Within the French contribution, CEA is responsible for the assembly, in a dedicated facility located in Saclay, of the up to 100 cryomodules constituting the Linac. Since 2012, ALSYOM has been selected as the industrial partner for such assembly works. This presentation will detail the organization set up for this partnership and the related challenges of this transfer to Industry.

Slides WEIB04 [1.962 MB]

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WEPRO003

Construction of a Laser Compton Scattered Photon Source at cERL

photon, laser, electron, gun

1940

R. Nagai, R. Hajima, M. Mori, T. Shizuma
JAEA, Ibaraki-ken, Japan
T. Akagi, Y. Honda, A. Kosuge, J. Urakawa
KEK, Ibaraki, Japan

A nondestructive assay system of isotopes by quasi-monochromatic gamma-rays and nuclear resonance fluorescence is under development in JAEA. The quasi-monochromatic gamma-rays are generated by laser Compton scattering (LCS) based on energy-recovery linac accelerator and laser technologies. In order to demonstrate the accelerator and laser performance required for the gamma-ray source, an LCS experiment is planned at Compact ERL (cERL) at KEK. A mode-locked fiber laser, laser enhancement cavity, beamline, and experimental hatch are under construction for the LCS experiment. Up-to-date construction status is presented in detail.

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WEPRO005

Development of Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources

HOM, linac, brightness, photon

1946

M. Sawamura, R. Hajima, R. Nagai
JAEA, Ibaraki-ken, Japan
H. Fujisawa, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
T. Kubo
KEK, Ibaraki, Japan

Funding: This work is supported by Photon and Quantum Basic Research Coordinated Development Program.
We have launched a 5-year research program to develop superconducting spoke cavity for laser Compton scattered (LCS) photon sources. For realizing a wide use of LCS X-ray and gamma-ray sources in academic and industrial applications, we adopt 325-MHz superconducting spoke cavity to electron beam drivers for the LCS sources. The spoke cavity, originally invented for ion and proton acceleration, can be used for electron accelerators, in which we can make best use of features of spoke cavity: relative compactness in comparison with a TM cavity of the same frequency, robustness with respect to manufacturing inaccuracy due to its strong cell-to-cell coupling, couplers on outer conductor for the better packing in a linac, and so on. In this paper, we present our research plan and results of cavity shape optimization.

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WEPRO007

Nanometer Scale Coherent Current Modulation via a Nanotip Cathode Array and Emittance Exchange

electron, emittance, gun, linac

1952

E.A. Nanni, W.S. Graves
MIT, Cambridge, Massachusetts, USA
P. Piot
Fermilab, Batavia, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: NSF DMR-1042342, DARPA N66001-11-1-4192
We present PIC simulations of electron bunches with nm scale longitudinal modulation produced using a compact 2-20 MeV LINAC. The modulation is initially imparted in the transverse dimension of the electron bunch with a nano-patterned photo-emitter in a X-band RF gun with 2 MeV exit energy. The electron bunch passes through a 1 m standing wave X-band LINAC which can raise the beam energy up to 20 MeV. The transverse modulation is exchanged into the longitudinal dimension using a double dog-leg emittance exchange setup with a 5 cell RF deflector cavity. The modulation pitch can be tuned by adjusting the spacing of the nano-patterned photo-emitter or magnification of the transverse pitch with electron optics. The electron beam parameters are optimized to produce coherent XFEL radiation upon interacting with a “laser undulator”.

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WEPRO018

Theoretical Maximum Current of the NSLS-II Linac

linac, simulation, beam-loading, gun

1980

R.P. Fliller, F. Gao, G.M. Wang
BNL, Upton, Long Island, New York, USA

Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
An analysis of the maximum available NSLS-II linac current was performed as part of the preparation for NSLS-II Booster commissioning. The analysis was necessary in order to establish the maximum beam current available from the linac and the maximum current that would be available to the booster accelerator. In this paper we discuss the assumptions that were used in determining the maximum linac current, the model of the linac and comparison to operational conditions.

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WEPRO052

The ThomX Project Status

laser, framework, synchrotron, gun

2062

A. Variola, D. Auguste, A. Blin, J. Bonis, S. Bouaziz, C. Bruni, K. Cassou, I. Chaikovska, S. Chancé, V. Chaumat, R. Chiche, P. Cornebise, O. Dalifard, N. Delerue, T. Demma, I.V. Drebot, K. Dupraz, N. El Kamchi, M. El Khaldi, P. Gauron, A. Gonnin, E. Guerard, J. Haissinski, M. Jacquet, D. Jehanno, M. Jouvin, E. Jules, F. Labaye, M. Lacroix, M. Langlet, D. Le Guidec, P. Lepercq, R. Marie, J.C. Marrucho, A. Martens, B. Mercier, E. Mistretta, H. Monard, Y. Peinaud, A. Pérus, B. Pieyre, E. Plaige, C. Prevost, T. Roulet, R. Roux, V. Soskov, A. Stocchi, C. Vallerand, A. Vermes, F. Wicek, Y. Yan, J.F. Zhang, Z.F. Zomer
LAL, Orsay, France
P. Alexandre, C. Benabderrahmane, F. Bouvet, L. Cassinari, M.-E. Couprie, P. Deblay, Y. Dietrich, M. Diop, M.E. El Ajjouri, M.P. Gacoin, C. Herbeaux, N. Hubert, M. Labat, P. Lebasque, A. Lestrade, R. Lopes, A. Loulergue, P. Marchand, F. Marteau, D. Muller, A. Nadji, R. Nagaoka, J.-P. Pollina, F. Ribeiro, M. Ros, R. Sreedharan
SOLEIL, Gif-sur-Yvette, France
A. Bravin, G. Le Duc, J. Susini
ESRF, Grenoble, France
C. Bruyère, A. Cobessi, W. Del Net, J.L. Hazemann, J.L. Hodeau, P. Jeantet, J. Lacipière, O. Proux
Institut NEEL, Grenoble, France
E. Cormier, J. Lhermite
CELIA, Talence, France
L. De Viguerie, H. Rousselière, P. Walter
LAMS, Universite Pierre et Marie Curie, Ivry Sur Seine, France
H. Elleaume, F. Esteve
INSERM, Grenoble Institut des Neurosciences, La Tronche, France
J.M. Horodinsky, N. Pauwels, P. Robert
CNRS (IRSD), Orsay, France
S. Sierra
TED, Velizy, France

Funding: Work supported by the French Agence Nationale de la Recherche as part of the program EQUIPEX under reference ANR-10-EQPX-51, the Ile de France region, CNRS-IN2P3 and Université Paris Sud XI
A collaboration of seven research institutes and an industry has been set up for the ThomX project, a compact Compton Backscattering Source (CBS) based in Orsay – France. After a period of study and definition of the machine performances a complete description of all the systems has been provided. The infrastructures work is started and the main systems are in the call for tender phase. In this paper we will illustrate the definitive machine parameters and components characteristics. We will also update the results of the different ongoing R&D on optical resonators, fast power supplies for the injection kickers and on the electron gun.

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WEPRO056

Development of an Optical Resonant Cavity for the LCS Experiment at cERL

laser, photon, experiment, resonance

2072

T. Akagi, Y. Honda, A. Kosuge, J. Urakawa
KEK, Ibaraki, Japan
R. Hajima, M. Mori, R. Nagai, T. Shizuma
JAEA, Ibaraki-ken, Japan

A nondestructive assay system of isotopes by quasi-monochromatic gamma-rays by laser Compton scattering (LCS) is under development. In order to demonstrate the accelerator and laser performance required for the gamma-ray source, an LCS experiment is planned at Compact ERL (cERL) at KEK. An optical resonant cavity is under construction for the LCS experiment. The new optical cavity is designed by combination of two bow-tie cavities to achieve fast optical polarization switching. The performance of the optical cavity is presented in detail.

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WEPRO064

Recent Results of the HESR RF System

operation, impedance, electron, accumulation

2094

R. Stassen, F.J. Etzkorn, R. Greven, T. Katayama, R. Maier, G. Schug, H. Stockhorst
FZJ, Jülich, Germany

The FAIR complex (Facility for Antiprotons and Ion Research) will be built in different stages. Due to the postponed RESR in the first stage, both RF-cavities of the HESR have to operate in different modes to achieve the required beam quantity and quality. The RF-system of the HESR will now consists of two identical cavities with a common low-level RF control (LLRF). Both cavities will be driven by low noise solid state amplifiers. Each cavity contains of one gap and two tanks operating in push-pull mode and each tank will house 6 ring cores wound of modern magnetic nano-alloy ribbon. Meanwhile all ring cores were delivered and first results at low power and at high power will be presented. The construction of the new air cooling concept is now in the final stage.

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WEPRO090

Status of KAERI 6 MeV 9.3 GHz X-Band Electron Linac for Cancer Treatment System

linac, electron, gun, radiation

2168

B.N. Lee, B.C. Lee, S.H. Lee, S. Lee, H.D. Park, K.B. Song
KAERI, Dae-jeon, Republic of Korea
P. Buaphad, Y. Kim
ISU, Pocatello, Idaho, USA
S.S. Cha
UST, Daejeon City, Republic of Korea

Funding: This work was supported by a grant from the (NRF funded by the MSIFP, Korea (No.2013M2A2A4023350) and the Industrial Strategic technology development program, 10043897, funded By the MOTIE, Korea.
The X-band RF linear accelerators (LINAC’s) are popular for medical application due to its compactness. To increase the precision of treatment accuracy under circumstance in which the LINAC is mounted on an apparatus such as gantry frame or robot-arm; this is an advantage as the weight and size are more reduced. It is a 9.3 GHz magnetron with the most readily available RF generator in the X-band frequencies from 8 GHz to 12 GHz and the magnetron is mainly used for the source of the RF power in a compact LINAC. The average power of the magnetron at 9.3~GHz is generally a few MW and this amount could provide a sufficient radiation dose-rate for tumour therapy. KAERI has been developing a new compact 9.3 GHz X-band electron LINAC for a cancer treatment system. The maximum energy of the electron beam is 6 MeV and the average beam power at the tungsten target is about 1 kW. In this paper, we describe the status of development of the 6 MeV X-band LINAC at KAERI.

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WEPRO096

X-ray Radiation Source for Low Dose Angiography based on Channeling Radiation

radiation, electron, optics, photon

2186

S.M. Polozov, T.V. Bondarenko
MEPhI, Moscow, Russia

Angiography is one of the most reliable and contemporary procedure of the vascular system imaging. X-ray spectrums provided by all modern medical angiographs are too broad to acquire high contrast images and provide low radiation dose at the same time. The new method of narrow X-ray spectrum achieving is based on the idea of channelling radiation application. The X-ray filters used in this method allows eliminating the high energy part of the spectrum and providing dramatic dose reduction. The scheme of the facility including the X-ray filter is discussed. The results of the spectrum analysis for the channelling radiation source and typical angiography X-ray tube are discussed. Doses obtained by the water phantom and contrast of the iodine agent image are also provided for both cases.

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WEPME002

Laser System for SNS Laser Stripping Experiment

laser, controls, experiment, neutron

2254

Y. Liu, C. Huang, A. Rakhman
ORNL, Oak Ridge, Tennessee, USA

Funding: This work is funded by the U.S. DOE under grant number DE-FG02-13ER41967, and by the U.S. DOE under contract number DE-AC05-00OR22725 with UT-Battelle Corporation.
The Spallation Neutron Source (SNS) accelerator complex utilizes charge-exchange injection to stack a high-intensity proton beam in the accumulator ring for short-pulse neutron production. A foil-less charge exchange injection method was researched at SNS by using a laser assisted H⁻ beam stripping scheme. Following a proof-of-principle experiment using a Q-switched laser, a new experiment is being prepared to demonstrate laser stripping over a 10-us macropulse. In this talk, we will report the design and measurement results of the laser system for the next stage laser stripping experiment. The laser system adopts a master oscillator power amplifier (MOPA) configuration and contains an actively mode-locked fiber seeder, macropulse generator, multiple-stage Nd:YAG amplifiers, harmonic converters, and control electronics. The laser system generates 50 ps/402.5 MHz pulses (at a macropulse mode) with multiple megawatt peak power at a wavelength of 355 nm. The measurement results of laser pulse width, spectrum, spatial/temporal beam quality and their parameter dependence will be described.

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WEPME003

Two Years Experience with the Upgraded ELBE RF System Driven by 20kW Solid State Amplifier Blocks (SSPA)

operation, klystron, linac, SRF

2257

H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert
HZDR, Dresden, Germany

Since January 2012 the Superconducting CW Linac ELBE is equipped and in permanent operation with four 20 kW Solid State Amplifier Blocks. The poster gives an overview on the design of the new RF system and the experience gained within the first two years of operation.

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WEPME004

Prediction of Severe Electron Loading of High-gradient Accelerating Structures based on Field Emission Measurements of Nb and Cu Samples

electron, vacuum, high-voltage, factory

2258

S. Lagotzky, G. Müller
Bergische Universität Wuppertal, Wuppertal, Germany

Funding: The work is funded by BMBF project 05H12PX6.
Enhanced field emission (EFE) limits the performance of both superconducting and normal conducting high-gradient accelerating structures. Systematic field emission scanning microscopy and correlated SEM/EDX measurements of relevant Nb and Cu samples have revealed particulates and surface irregularities with field enhancement factors b = 10 - 90 as origin of EFE. Based on sufficient emitter statistics, an exponential increase of the emitter number density N with increasing surface field (E) was found. This allows a prediction of the EFE loading of future ILC and CLIC accelerating structures by scaling of N to relevant E and using a weighted integration over the high-field cavity surface. Accordingly, an electropolished (Ra < 300 nm) and dry-ice cleaned (DIC) TESLA-shape 9-cell 1.3 GHz Nb cavity * will still suffer from EFE at Eacc = 35 MV/m (N = 0.3 /cm² at Epeak = 70 MV/m). Moreover, a diamond-turned, chemically etched and DIC 11.2 GHz Cu structure ** will breakdown at Eacc = 100 MV/m (N = 20 /cm² at Epeak = 243 MV/m). Possible improvements, i.e. by emitter processing will be discussed.
* ILC Technical Design Report (2013)
** A. Grudiev and W. Wuensch, Proceedings of LINAC2010, Tsukuba, Japan, pp. 211 - 213

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WEPME007

Multi-Bunch Generator Cavity

impedance, electron, cathode, coupling

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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WEPME008

72 MHz Solid-state Amplifier Power Test

operation, cyclotron, controls, impedance

2270

A.Yu. Smirnov, E.V. Ivanov, A.A. Krasnov, S.A. Polikhov, I. Řežanov
Siemens Research Center, Moscow,, Russia
G.B. Sharkov
Siemens LLC, Moscow, Russia

In this paper, we present the performance of 72 MHz 18 kW RF power source developed for cyclotrons. The machine is equipped with 9 class-AB power amplifier modules (each with up to 2 kW output) based on highly reliable LDMOS transistors. The whole system is arranged inside a single 19" cabinet and has coaxial 50 Ω output. The test environment and high power measurement results are described.

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WEPME020

Commissioning of the MICE RF System

operation, power-supply, experiment, high-voltage

2297

A.J. Moss, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.M.H. Alsari
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
A.J. Dick, K. Ronald, D.C. Speirs, C.G. Whyte
USTRAT/SUPA, Glasgow, United Kingdom
T. Stanley
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
C.J. White
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The Muon Ionisation Cooling Experiment (MICE) is being constructed at Rutherford Appleton Laboratory in the UK. The muon beam will be cooled using multiple hydrogen absorbers then reaccelerated using an RF cavity system operating at 201MHz. This paper describes recent progress in commissioning the amplifier systems at their design operation conditions, installation and operation within the Ionisation Cooling Test Facility (ICTF) as part of the MICE project.

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WEPME024

Power Coupler Manufacturing and Quality Control at CPI

linac, controls, SRF, target

2308

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

CPI has been designing and manufacturing fundamental power couplers for superconducting accelerators for over a dozen years. We have manufactured approximately 200 power couplers of 16 different designs. Power coupler frequencies have ranged from 175 MHz to 3.9 GHz and power levels have ranged from 5 kW to 500 kW average power. We have developed and qualified several key manufacturing processes including a high-RRR copper plating process and a titanium nitride coating process. In addition, we have established uniform quality control and inspection processes which ensure that the power couplers will meet the requirements for the intended use in superconducting accelerators. These processes have been developed, improved and/or qualified in collaboration with colleagues at superconducting accelerator facilities throughout the world. This paper will provide an overview of these critical manufacturing and quality control processes.

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WEPME061

Ytterbium Fiber and Disk Laser of RF Gun for SuperKEKB

laser, gun, background, emittance

2415

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

For SuperKEKB project, the electron beams with a charge of 5 nC and a normalized emittance of 10 μm are expected to be generated in the photocathode RF gun at the injector linac. An ytterbium (Yb)-doped laser system with a center wavelength of 259 nm and a pulse width of 30 ps is employed to obtain high peak energy pulses. Although, the pulse repetition of 25 Hz with double-bunch is required, more than 5 nC electron with single-bunch has so far been generated in the 2 Hz.

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WEPME062

A New Digital LLRF System for a Fast Ramping Storage Ring

LLRF, feedback, operation, injection

2418

M. Schedler, F. Frommberger, W. Hillert, D. Proft, D. Sauerland
ELSA, Bonn, Germany
D. Teytelman
Dimtel, San Jose, USA

At the Electron Stretcher Facility ELSA of Bonn University, an upgrade of the maximum stored beam current from 20 mA to 200 mA is planned. The storage ring operates applying a fast energy ramp of 6 GeV/s from 1.2 GeV to 3.5 GeV and a slow extraction afterwards over a few seconds to the hadron physics experiments. The intended upgrade is mainly limited by the coupled-bunch instabilities and the ability of bunch-by-bunch feedback systems to suppress such instabilities. In order to achieve optimum bunch-by-bunch feedback performance, the beam phase with respect to the master oscillator and the synchrotron frequency have to stay constant. This paper reports on a new high performance low level RF (LLRF) system. The system stabilizes the cavity field and is capable of executing fast voltage and phase ramps. The LLRF uses FPGA-based digital signal processing and includes cavity tuner control as well as fast interlocks and extensive diagnostics.

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WEPME066

High Speed Digitial LLRF Feedbacks for Normal Conducting Cavity Operation

LLRF, gun, operation, klystron

2430

M. Hoffmann, L. Butkowski, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Köhler
DESY Zeuthen, Zeuthen, Germany
A. Piotrowski
TUL-DMCS, Łódź, Poland
I. Rutkowski, R. Rybaniec
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

In the first half of the year 2014, the MTCA.4 based LLRF control system will be installed at several facilities (FLASH RF Gun, REGAE, PITZ, FLUTE/KIT). First tests during the last year show promising results in optimizing the system for high speed digital llrf feedbacks (reducing system latency, increase internal controller processing speed). In this contribution we will present further improvements in latency and performance optimization of the system, results and gained experience from the commisioning of the system at the metioned facilities.

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WEPME071

Development and Construction Status of New LLRF Control System for SuperKEKB

controls, LLRF, FPGA, klystron

2444

T. Kobayashi, K. Akai, K. Ebihara, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri
KEK, Ibaraki, Japan
H. Deguchi, K. Hayashi, T. Iwaki, M. Ryoshi
Mitsubishi Electric TOKKI Systems, Amagasaki, Hyogo, Japan

Beam commissioning of the SuperKEKB will be started in 2015. A new LLRF control system, which is an FPGA-based digital RF feedback control system on the MicroTCA platform, has been developed to satisfy the requirement for high current beam operation of the SuperKEKB. Then final refinements were applied, and now the quantity production is in progress. As a new function, klystron phase lock loop was additionally implemented within the cavity feedback control loop in the FPGA, and it was successfully worked in the low-level operation test. For the SuperKEKB, damping ring (DR) is required for the positron injection. Therefore another new LLRF control system is under development for the DR-RF system. It is operated at the same RF-frequency as the main ring, and vector sum control of three cavities is needed in the DR-LLRF control. In this report, the development status and progress from the previous report will be presented including the RF reference distribution system.

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WEPME072

Performance of the Digital LLRF System at the cERL

LLRF, controls, linac, feedback

2447

F. Qiu, D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura
KEK, Ibaraki, Japan

A digital low-level radio frequency (LLRF) system has been developed and evaluated at compact Energy Recovery Linac (cERL) in High Energy Accelerator Research Organization (KEK), Japan. A total of three two-cell cavities were installed for the injector, and two nine-cell cavities were installed for the main linac. The required RF stabilities for these cavities are 0.1% rms in amplitude and 0.1° rms in phase. To satisfy these requirements, we survey feedback parameters such as the proportional and integral (PI) gains. Furthermore, we evaluated the beam energy fluctuation due to the vector-sum controlling error between the cavities injectors 2 and 3. Finally, we present the performance of the LLRF system that was realized in the beam commissioning. This paper describes the current status of the LLRF system.

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WEPME073

Performance of RF System for Compact-ERL Main Linac at KEK

feedback, controls, linac, LLRF

2450

T. Miura, M. Akemoto, A. Akiyama, D.A. Arakawa, S. Fukuda, H. Honma, H. Katagiri, T. Matsumoto, H. Matsushita, S. Michizono, H. Nakajima, K. Nakao, F. Qiu, H. Sakai, T. Shidara, T. Takenaka, K. Umemori, Y. Yano
KEK, Ibaraki, Japan

The construction of compact ERL in the first stage has been completed in the end of 2013. The rf commissioning in main-linac has been started. The main-linac consists of two nine-cell cavities. The loaded Q is high, ~10⁷. As the rf power sources, a solid state power amplifier and an inductive output tube (IOT) has been used for two cavities, respectively. The RF field and tuner have been successfully controlled by using micro-TCA digital feedback board. This paper reports about the RF commissioning and the performance.

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WEPME075

Real-time Estimation of Superconducting Cavities Parameters

controls, operation, FPGA, LLRF

2456

R. Rybaniec
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
V. Ayvazyan, J. Branlard, L. Butkowski, S. Pfeiffer, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Cichalewski, K.P. Przygoda
TUL-DMCS, Łódź, Poland

Performance of accelerators based on the superconductive cavities including FLASH and XFEL facilities at DESY is affected by cavity parameters variation over time. High gradient electromagnetic field inside cavities causes detuning due to the Lorentz force. In addition the quality factor of cavities can change during the RF field pulse. Currently used method for estimation of those parameters is based on the post-processing of the data recorded during operation of the RF. External servers calculate cavity parameters using cavity equation, forward power and probe signals collected during previous pulse. A novel approach* based on the component implemented in FPGA is presented. In the new method loaded quality factor and detuning are estimated in real-time during the RF pulse for increased reliability and better exception handling. Modified firmware of the LLRF control system based on the Micro Telecommunications Computing Architecture (MTCA) platform has been used for the method verification.
*”Development of Control System for Fast Frequency Tuners of Superconducting Resonant Cavities for FLASH and XFEL Experiments”, K. Przygoda, PhD thesis, Technical University of Łódź, Poland, 2010.

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WEPME077

Advanced Automatic Frequency Control System for a Dual Energy S-band RF Electron Linear Accelerator

resonance, controls, electron, simulation

2459

S.S. Cha
UST, Daejeon City, Republic of Korea
Y. Kim
ISU, Pocatello, Idaho, USA
B.C. Lee, B.N. Lee, H.D. Park, K.B. Song
KAERI, Daejon, Republic of Korea

Funding: This work was supported by a National Research Foundation of Korea (NRF) grant funded by the ministry of science ICT & future Planning (No. 2010-0026088), and MOTIE Korea (13-DU-EE-12).
The Radiation Instrumentation Research Division of Korea Atomic Energy Research Institute is developing a 2856 MHz dual energy [9, 6 MeV] s-band RF electron linear accelerator for security inspection. The s-band dual energy electron accelerator generates dual x-ray energy by irradiating a bunched electron beam from the cavity to a tungsten target. By detecting an x-ray, the cargo security inspection system can distinguish between organic and inorganic materials. Synchronization of the resonant frequency between the cavity and RF driver is an important factor for the stable operation of an accelerator. With a low RF driver power using the AFC, stable accelerator operations and a uniform output beam power can be obtained. This indicates that an accurate cargo inspection is possible. We used phase a frequency detector that can detect a wide frequency band and synchronize the resonance frequency between the RF driver and cavity. In this paper, we introduce a more advanced AFC system than a conventional AFC system.

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WEPME079

LLRF System for the ESS Proton Accelerator

LLRF, timing, controls, monitoring

2465

A.J. Johansson, F. Kristensen, A.M. Svensson
Lund University, Lund, Sweden
R. Zeng
ESS, Lund, Sweden

The European Spallation Source is driven by a proton linear accelerator that will have an average beam power of 5 MW. The accelerator is pulsed at 14 Hz with a pulse length of 2.86 ms, and consists of both normal conduction and superconducting accelerating structures. The long pulse and the high goals of energy efficiency and availability create special challenges for the LLRF system.

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WEPME083

VELA: A New Accelerator Technology Development Platform for Industry

electron, FEL, target, experiment

2471

P.A. McIntosh, D. Angal-Kalinin, R.K. Buckley, S.R. Buckley, J.A. Clarke, P.A. Corlett, B.D. Fell, A.R. Goulden, C. Hill, F. Jackson, S.P. Jamison, J.K. Jones, L.B. Jones, A. Kalinin, L. Ma, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, T.C.Q. Noakes, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, S.L. Smith, T.T. Thakker, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
N. Bliss, G. Cox, G.P. Diakun, A. Gleeson, T.J. Jones, K. Robertson, M.D. Roper, E. Snedden
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom
N.J. Boulding
FMB Oxford, Oxford, United Kingdom
A. Lyapin
JAI, Egham, Surrey, United Kingdom
E.J. Morton
CXR Ltd, Guildford, United Kingdom

The Versatile Electron Linear Accelerator (VELA) facility will provide enabling infrastructures targeted at the development and testing of novel and compact accelerator technologies, specifically through partnership with industry and aimed at addressing applications in medicine, health, security, energy and industrial processing. The facility has now been commissioned at Daresbury Laboratory and the facility is now being actively utilised by industrial groups who are able to take advantage of the variable electron beam parameters available on VELA to either demonstrate new techniques and/or processes or otherwise develop new technologies for future commercial realisation. Examples of which to be presented include; demonstration of a new cargo scanning process, characterisation of novel, high performance beam position monitors, as well as other technology development applications.

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WEPRI001

Clean Room Integration of the European XFEL Cavity Strings

vacuum, cryomodule, quadrupole, alignment

2474

S. Berry, O. Napoly, B. Visentin
CEA/DSM/IRFU, France
F. Chastel, A. Clippet, M. Mbeleg, P. Pluvy
ALSYOM, Argebteuil, France
C. Cloué, C. Madec, T. Trublet
CEA/IRFU, Gif-sur-Yvette, France

The 101 cryomodules of the XFEL cold linac will be integrated at Saclay under the CEA responsability by the industrial operator ALSYOM, at the production rate of cryomodule per week. Each cryomodule includes a string of 8 Niobium superconducting cavities and a BPM-quadripole unit (downstream end). To avoid particle contamination of the RF cavities, the strings are assembled in an ISO4 cleanroom by following strict cleaning and high-vacuum procedures. The major technical challenge of the string integration thus lies in the capacity to realize 25 connections in two weeks while protecting the cavity and coupler RF surfaces and to check their leak-tightness up to 10-10 hPA.l/s. The partial demonstration was made by the CEA team with the first pre-series module XM-3 which achieves a total accelerating voltage of 232 MV preserving the individual performances of cavities. In this paper the status and challenges of the production line is presented, including the quality management, equipment and operator training aspects. The optimisation process toward a faster assembly while preserving or actually decreasing the cavity exposure to contamination sources is also described.

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WEPRI002

Status and First Results of Two High Beta Prototype Elliptical Cavities for ESS

cryomodule, accelerating-gradient, operation, niobium

2477

F. Peauger, P. Bosland, P. Carbonnier, G. Devanz, F. Éozénou, X. Hanus, P. Hardy, V.M. Hennion, J. Plouin, D. Roudier, C. Servouin
CEA/DSM/IRFU, France
C. Darve, S. Molloy
ESS, Lund, Sweden
L. Maurice
CEA/IRFU, Gif-sur-Yvette, France
G. Olivier
IPN, Orsay, France

Two prototypes of elliptical superconducting cavities have been designed and manufactured in the frame of the French-Swedish agreement for ESS. These 5-cell cavities have a beta value of 0.86 and their frequency is 704.42 MHz. The nominal accelerating gradient on the ESS accelerator is 19.9 MV/m at 2K. We present the manufacturing status of the cavities by two different vendors as well as the specific means which have been developed for the cavity treatments performed at CEA after delivery. We emphasis the activities performed on the first bare cavities recently received at CEA such as the RF measurement and tuning operations, the cleaning and chemical treatments and the clean room assembly including high pressure rinsing. Finally, first test results at 2K in vertical cryostat are reported.

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WEPRI004

Operational Experience and Upgrades of the SOLEIL Storage Ring RF System

operation, vacuum, cryogenics, SRF

2480

P. Marchand, J.P. Baete, R.C. Cuoq, H.D. Dias, M. Diop, J.L. Labelle, R. Lopes, M. Louvet, C.M. Monnot, L.S. Nadolski, S. Petit, F. Ribeiro, T. Ruan, R. Sreedharan, K. Tavakoli
SOLEIL, Gif-sur-Yvette, France

In the SOLEIL storage ring, two cryomodules provide to the electron beam an accelerating voltage of 3-4 MV and a power of 575 kW at 352 MHz. Each cryomodule contains a pair of superconducting cavities, cooled with liquid Helium at 4.5 K, which is supplied by a single 350 W cryogenic plant. The RF power is provided by four solid state amplifiers, each delivering up to 180 kW. The parasitic impedances of the high order modes (HOM) are strongly mitigated by means of four coaxial couplers, located on the central pipe connecting the two cavities. Eight years of operational experience with this system, as well as its upgrades, are reported.

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WEPRI005

Processing and Testing of the SRF Photoinjector Cavity for BERLinPro

SRF, operation, electron, niobium

2484

A. Burrill, W. Anders, A. Frahm, J. Knobloch, A. Neumann
HZB, Berlin, Germany
G. Ciovati, W.A. Clemens, P. Kneisel, L. Turlington
JLab, Newport News, Virginia, USA
E.N. Zaplatin
FZJ, Jülich, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
The BERLinPro project is a compact, c.w. SRF energy recovery linac (ERL) that is being built to develop the accelerator physics and technology required to operate the next generation of high current ERLs. The machine is designed to produce a 50 MeV 100 mA beam, with better than 1 mm-mrad emittance. The electron source for the ERL will be a SRF photoinjector equipped with a multi-alkali photocathode. In order to produce a SRF photoinjector to operate reliably at this beam current HZB has undertaken a 3 stage photoinjector development program to study the operation of SRF photoinjectors in detail. The 1.4 cell cavity being reported on here is the second stage of this development, and represents the first cavity designed by HZB for use with a high quantum efficiency multi-alkali photocathode. This paper will describe the work done to prepare the cavity for RF testing in the vertical testing dewar at Jefferson Laboratory as well as the results of these RF tests.

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WEPRI006

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

booster, SRF, linac, coupling

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

booster, SRF, emittance, coupling

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

HOM, damping, coupling, 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, HOM, coupling, 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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WEPRI011

Progress of R&D on SRF Cavities at DESY towards the ILC Performance Goal

SRF, factory, accelerating-gradient, electron

2499

A. Navitski
DESY, Hamburg, Germany
A. Prudnikava, Y. Tamashevich
Uni HH, Hamburg, Germany

Funding: BMBF project 05H12GU9, Alexander von Humboldt Foundation, CRISP (No. 283745) and ”Construction of New Infrastructures-Preparatory Phase” ILC-HiGrade (No. 206711) of the EU 7th FP7/2007-2013 Programme.
The R&D program of the ILC-HiGrade group at DESY aims at a solid understanding and control of the industrial mass-production process of the superconducting radio-frequency accelerating cavities that are being manufactured for the European X-ray Free Electron Laser (EXFEL). This accelerator is currently under construction at DESY. As well as the main production cavities for XFEL, 24 additional cavities are being constructed as part of the ILC-HiGrade program. The goal is to identify the gradient-limiting factors and further refine the cavity-treatment technique to understand how to achieve gradients above 35 MV/m at >90% production yield in an industrial context. Techniques such as 2nd sound and temperature mapping for the quench detection, OBACHT optical inspections, as well as Centrifugal Barrel Polishing (CBP) and Local Grinding repair are foreseen as tools. Actual status, details, and achievements will be reported.

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WEPRI012

Euclid Modified SRF Conical Half-wave Resonator Design

vacuum, simulation, controls, operation

2502

E.N. Zaplatin
FZJ, Jülich, Germany
T.L. Grimm, A. Rogacki
Niowave, Inc., Lansing, Michigan, USA
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302.
The new low-beta conical Half-Wave Resonator (cHWR) is suggested for CW proton accelerators of new generation with relatively low beam loading, where frequency detune caused by microphonics and helium pressure fluctuations is essential. This particular design, considered in the paper, has operation frequency of 162.5 MHz, b=v/c=0.11, and is suitable for the first section of the PIP-II superconducting accelerator which is under development at Fermilab. The main idea of the cHWR design is to provide a self-compensation cavity design together with its helium vessel to minimize the resonant frequency dependence on external loads. A unique cavity side-tuning option is also under development. Niowave, Inc. proposed a series of cavity and helium vessel modifications to simplify their manufacturing. The whole set of numerical simulations has been generated to verify that the main parameters of the initial structure design were not affected by the proposed modifications. Here we present the main results of the cavity and helium vessel modified design.

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WEPRI016

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

HOM, coupling, 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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WEPRI018

Status of the Fabrication of the XFEL 3.9 GHz Cavity Series

status, linac, vacuum, gun

2512

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

The third harmonic system at 3.9 GHz of the European XFEL (E-XFEL) injector section will linearize the bunch RF curvature, induced by first accelerating module, before the first compression stage and it is a joint INFN and DESY contribution to the project. This paper presents the status of the fabrication of the 3.9 GHz cavity series in view of the XFEL injector commissioning in 2015.

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WEPRI020

Mechanical Analysis of the XFEL 3.9 GHz Cavities in support of PED Qualification

simulation, superconducting-cavity, controls, linac

2515

M. Moretti, P. Pierini
INFN/LASA, Segrate (MI), Italy
A. Schmidt
DESY, Hamburg, Germany

We present the FEA stress analysis under different mechanical conditions of the XFEL 3.9 GHz superconducting cavities. The analysis is being performed in support of the necessary qualification according to the Pressure Equipment Directive European Norms, for the operating conditions set in the European XFEL project.

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WEPRI022

In-house Production of a Large-Grain Single-Cell Cavity at Cavity Fabrication Facility and Results of Performance Tests

accelerating-gradient, SRF, radio-frequency, vacuum

2519

T. Kubo, Y. Ajima, H. Inoue, K. Umemori, Y. Watanabe, M. Yamanaka
KEK, Ibaraki, Japan

We studied electron beam welding (EBW) conditions for large grain Nb, and fabricated a single cell cavity in Cavity Fabrication Facility (CFF), KEK. Vertical-test results of the cavity made from large grain Nb are also presented.

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WEPRI024

Two-Dimensional Models of the Magnetic-Field Enhancement at Pit and Bumps

SRF, photon

2525

T. Kubo
KEK, Ibaraki, Japan

Analytical models of the magnetic field enhancement at pits were presented at SRF2013 last year*. Other simple models will be addressed in this paper.
* Proceedings of SRF2013, Paris, France (2013), p. 430

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WEPRI025

Studies of Fabrication Procedure of 9-cell SRF Cavity for ILC Mass-production at KEK.

HOM, electron, gun, linear-collider

2528

T. Saeki, Y. Ajima, K. Enami, H. Hayano, H. Inoue, E. Kako, S. Kato, S. Koike, T. Kubo, S. Noguchi, M. Satoh, M. Sawabe, T. Shishido, A. Terashima, N. Toge, K. Ueno, K. Umemori, K. Watanabe, Y. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, M. Yamanaka, K. Yokoya
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
N. Kawabata, H. Nakamura, K. Nohara, M. Shinohara
SPS, Funabashi-shi, Japan
F. Yasuda
The University of Tokyo, Institute of Physics, Tokyo, Japan

We had been constructing a new facility for the fabrication of superconducting RF cavity at KEK from 2009 to 2011. In the facility, we have installed a deep-drawing machine, a half-cup trimming machine, an electron-beam welding machine, and a chemical etching room in one place. We started the studies on the fabrication of 9-cell cavity for International Linear Collier (ILC) using this facility. The studies are focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC. We already finished the fabrication of two 9-cell cavities in this facility. This article reports the current status of the studies.

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WEPRI026

Mechanical Vibration Search of Compact ERL Main Linac Superconducting Cavities in Cryomodule

LLRF, operation, cryomodule, linac

2531

M. Satoh, K. Enami, T. Furuya, S. Michizono, T. Miura, F. Qiu, H. Sakai, K. Shinoe, K. Umemori
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

In 2014, we will start the beam operation in Compact ERL(cERL) by using main linac cryomodule, which contained the two 9-cell cavities. In principle, thanks to the mechanism of energy recovery, the input power of main linac of cERL is very small even if the beam current will be higher than 100mA. Therefore, the coupling is very weak. However, this coupling is perfectly not matched to the unloaded Q-value of the superconducting cavity like 1x10¹⁰. The minimum input power will be restricted by the cavity detuning due to the microphonics from the cryomodule itself. We designed the lower loaded Q-valued of (1-4)x10⁷ to reduce the effect of the michrophonics from the expected outer disturbance At present, we successfully suppressed the michrophonics to meet our requirement. However we found the enhancement of the detuning angle when we did not optimize the feedback loop of LLRF. This enhancement will be expected coming from the mechanical resonance frequencies of cavity and/or cryomodule. In this paper, we reported the correlation between the measured microphincs spectrum with LLRF in a beam operation and the results of the measured resonance frequencies spectrum at the test bench.

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WEPRI027

Performance Evaluation of ERL Main Linac Tuner

linac, operation, controls, feedback

2534

K. Enami, D.A. Arakawa, T. Furuya, S. Michizono, T. Miura, F. Qiu, H. Sakai, M. Satoh, K. Shinoe, K. Umemori
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

cERL project is now progressing. We are carrying on R&D for cERLmain linac consisted of 1.3GHz superconductive cavity. We evaluate slide jack tuner, which is component part of cryomodule. A slide jack tuner has 2 mechanism to tune frequency. One is slide jack mechanism that tunes roughly and the other is piezo mechanism that tunes finely. We carried out basic experiment and cold experiment. We finally confirmed that slide jack tuning system can tuning to target frequency 1.3GHz.

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WEPRI028

Operation Status of Compact ERL Main Linac Cryomodule

operation, linac, radiation, cryomodule

2537

K. Umemori, K. Enami, T. Furuya, S. Michizono, T. Miura, F. Qiu, H. Sakai, M. Satoh, K. Shinoe
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

We have developed a main linac cryomodule, in which two nine-cell HOM damped SRF cavities were mounted, for the Compact ERL (cERL) project in Japan. The main linac cryomodule is operated by a 2K refrigerator system, whose cooling ability is 80W. RF power is fed to each cavity from an IOT or a solid state amplifier. Amplitude and phase of RF stabilization is done by using a digital LLRF system. Cavity resonant frequency is controlled by using mechanical and piezo tuners. Before beam operation, performance test of the cryomodule has been carried out. Generally the cryomodule works well, but heavy field emission is rather problem. After construction of cERL circulation ring, we have a plan to do first beam operation with energy recovery mode, in this winter. Electron beam are accelerated up to 20 MeV. Heavy heat load to 2K Helium, caused by field emission, restrict cavity operation voltage. We report about a series of performance tests and a first experiment from beam operation.

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WEPRI029

Simulations and Measurements of Beam Pipe Modes excited in 9-cell Superconducting Cavities

HOM, dipole, simulation, experiment

2540

A. Kuramoto
Sokendai, Ibaraki, Japan
N. Baboi
DESY, Hamburg, Germany
H. Hayano
KEK, Ibaraki, Japan

Higher order modes (HOM) excited in 9-cell superconducting cavities have been studied to detect cavity alignment. Dipole modes have been monitored, since their magnitude is proportional to beam offsets from their electrical centers. Detection of cavity alignment is important for the ILC to confirm alignment accuracy and furthermore possible source of emittance growth. We are particularly interested in beam pipe modes because they are localized in both ends of the cavity. We measured beam-induced HOM in the STF accelerator at KEK in 2012 – 2013. From the results of the measurement, we found some modes whose behaviors are like dipole mode at around 2.1 GHz instead of 2.28 GHz as calculated by R. Wanzenberg for an ideal cavity [TESLA 2001-33, September 2001]. We also measured beam induced HOM in the TESLA superconducting cavities in FLASH at DESY. In order to identify beam pipe modes and to compare the measurement with the calculation, we calculate beam pipe modes of 9-cell superconducting cavity by CST MICROWAVE STUDIO 2012 and HFSS 12. We will discuss about these calculations and the measurement.

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WEPRI030

Multipactor Simulation on Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources

multipactoring, simulation, electron, acceleration

2543

Y. Iwashita, H. Fujisawa, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
R. Hajima, R. Nagai, M. Sawamura
JAEA, Ibaraki-ken, Japan
T. Kubo
KEK, Ibaraki, Japan

Funding: This work is supported by Photon and Quantum Basic Research Coordinated Development Program.
Superconducting spoke cavity for laser Compton scattered (LCS) photon sources is under development. The operating frequency is 325-MHz to accelerate electron beam for the LCS sources, where the size of the spoke cavity is less than a elliptical cavities with the same frequency. Because of the complicated shape of the cavity, it may be suffered from a strong multipactor effect. The recent results on the multipactor analysis will be presented.

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WEPRI032

First Cryomodule Test at AMTF Hall for The European X-ray Free Electron Laser (XFEL)

cryomodule, vacuum, free-electron-laser, laser

2546

K. Kasprzak, B. Dzieza, W. Gaj, D. Karolczyk, L.M. Kolwicz-Chodak, A. Kotarba, A. Krawczyk, K. Krzysik, W. Maciocha, A. Marendziak, K. Myalski, S. Myalski, T. Ostrowicz, B. Prochal, M. Sienkiewicz, M. Skiba, J. Świerbleski, M. Wiencek, J. Zbroja, P. Ziolkowski, A. Zwozniak
IFJ-PAN, Kraków, Poland

The Accelerator Module Test Facility (AMTF) at DESY in Hamburg is dedicated to the tests of RF cavities and accelerating cryomodules for the European X-ray Free Electron Laser (XFEL). The AMTF hall is equipped with two vertical cryostats, which are used for RF cavities testing and three test benches that will be used for tests of the accelerating cryomodules. Recently, the first cryomodule teststand (XATB3) was commissioned and the first XFEL cryomodule (XM-2) was tested by team of physicists, engineers and technicians from The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences in Kraków, Poland, as a part of Polish in-kind contribution to XFEL. This paper describes the preparation for the cryomodule test, differences with the old teststands CryoModule Test Bench (CMTB), the cryomodule test and the test procedure updates done at the AMTF test bench. The first test of the accelerating cryomodule on the AMTF was successfully performed and the preliminary test results are presented.

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WEPRI034

Analysis of BCP Characteristics for SRF Cavities

niobium, experiment, SRF, ion

2549

Y. Jung, H.J. Kim
IBS, Daejeon, Republic of Korea
H.H. Lee, H.C. Yang
KRICT, Daejoen, Republic of Korea

A chemical polishing process is well-known critical process for improving superconducting cavities such as a quality factor and an acceleration electric filed with additional temperature treatment. Especially, Buffered Chemical Polishing (BCP) has been widely used in SRF (Superconducting Radio Frequency) cavity processing. We performed BCP experiments with 1:1:1 and 1:1:2 of an etchant ratio (HF:HNO3:H3PO4). In fact, BCP experiments were carried out by using both undeformed (as-receoved) and deformed niobium samples. We will report baseline BCP results by analyzing surface states of niobium samples such as optical photographs, etch rates and AFM (Atomic Force Microscopy) depending on temperature and time.

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WEPRI035

Stiffening Structure of the HWR at RISP

simulation, target, controls, operation

2552

G.-T. Park, H.J. Cha, H. Kim, H.J. Kim, W.K. Kim
IBS, Daejeon, Republic of Korea

The HWR being developed in RISP, Korea is in its final stage of the design. We consider the effects of the stiffeners in the presence of the helium vessel on the various detunings such as cool down, helium pressure fluctuation, Lorentz pressure. The interaction of the stiffened cavity with the helium jacket is studied via the coupled simulation by ANSYS and the optimal specification of the stiffeners are determined. In addition, the expected frequency shift is predicted to establish the target frequency bfor the manufacturing. The effect of the vibrational motion is also studied.

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WEPRI036

Fabrication Design of QWR and HWR Cryomodules

cryomodule, vacuum, linac, cryogenics

2555

W.K. Kim, H. Kim, H.J. Kim, Y. Kim, M. Lee, G.-T. Park
IBS, Daejeon, Republic of Korea

The superconducting linac of RAON consists of five types of cryomodules. The cryomodules host QWR, HWR1, HWR2, SSR1, and SSR2 superconducting cavities. The cryomodules will be operated at 2K in order to test the performance of the superconducting cavities. The design of the cryomodule components is based on thermal shield to prevent incoming heat, two-phase pipe to supply superfluid helium, vacuum vessel for the formation of the internal vacuum, supporter parts for alignment and keeping structure, and magnetic shield to prevent external magnetic field. The detailed fabrication design of the cryomodules will be presented in this paper.

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WEPRI037

Comparison of High Order Modes Damping Techniques for 800 MHz Single Cell Superconducting Cavities

HOM, damping, luminosity, dipole

2558

Ya.V. Shashkov, N.P. Sobenin
MEPhI, Moscow, Russia
M. Zobov
INFN/LNF, Frascati (Roma), Italy

Currently, applications of 800 MHz harmonic cavities in both bunch lengthening and shortening regimes are under consideration and discussion in the framework of the High Luminosity LHC project. In this paper we study electromagnetic characteristics of high order modes (HOM) for a single cell 800 MHz superconducting cavity and arrays of such cavities connected by drifts tubes. Different techniques for the HOM damping such as beam pipe grooves, coaxial-notch loads, fluted beam pipes etc. are investigated and compared. The influence of the sizes and geometry of the drift tubes on the HOM damping is analyzed.

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WEPRI040

On the Optimal Design of Elliptical Superconducting Cavities

coupling, 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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WEPRI041

Progress of HOM Couplers for CERN SPL Cavities

HOM, simulation, niobium, factory

2568

K. Papke, F. Gerigk
CERN, Geneva, Switzerland
U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Work supported by the Wolfgang-Gentner-Programme of the Bundesministerium für Bildung und Forschung (BMBF)
In this paper we present the progress of the Higher-Order-Mode (HOM) coupler design for the high beta CERN SPL (Superconducting Proton Linac) cavities. This includes the RF transmission behavior as well as mechanical and thermal requirements and their optimizations. Warm RF measurements are presented for the first four high beta SPL Cavities made of bulk niobium. Moreover the first prototype of a HOMcoupler will be introduced and we discuss its characteristics and its tuning possibilities.

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WEPRI042

Nb Coated HIE-ISOLDE QWR Superconducting Accelerating Cavities: From Process Development to Series Production

niobium, cryomodule, cathode, SRF

2571

A. Sublet, I. Aviles Santillana, B. Bártová, S. Calatroni, N.M. Jecklin, I. Mondino, M. Therasse, W. Venturini Delsolaro, P. Zhang
CERN, Geneva, Switzerland
M. Cantoni
EPFL, Lausanne, Switzerland

The new HIE-ISOLDE accelerator at CERN requires the production of 32 superconducting cavities (20 high-beta and 12 low-beta) in order to increase the energy of the rare isotope beam delivered to the experiments. The Quarter Wave Resonators (QWRs) cavities (0.3m diameter and 0.8m height) are made of OFE 3D-forged copper and are coated by DC-bias diode sputtering with a thin superconducting layer of niobium. Following a preliminary process development phase, the series production of the high-beta cavities has started. An overview of the development phase is presented, describing the key parameters varied to match the HIE-ISOLDE specifications (operation at 4.5 K with an accelerating field of 6 MV/m at 10W RF losses and Q0=4.5x108) and the resulting niobium film characteristics. The first series of cavities, produced using the baseline coating recipe, and their RF performance is reviewed.

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WEPRI045

Key Design Features of Crab-Cavity Cryomodule for HiLumi LHC

cryomodule, cryogenics, radiation, HOM

2580

S.M. Pattalwar, A.J. May, P.A. McIntosh, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, B.D.S. Hall
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
O. Capatina
CERN, Geneva, Switzerland
T.J. Jones, N. Templeton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
T.H. Nicol
Fermilab, Batavia, Illinois, USA

A prototype Superconducting RF (SRF) cryomodule, comprising multiple compact crab cavities is foreseen to realise a local crab crossing scheme for the “Hi-Lumi LHC”, a project launched by CERN to increase the luminosity performance of LHC. A cryomodule with two cavities will be initially installed and tested on the SPS drive accelerator at CERN to evaluate performance with high-intensity proton beams. STFC in collaboration with, University of Lancaster, CERN and FNAL has developed a concept cryomodule that has overcome most of the critical challenges imposed by a series of boundary conditions arising from; the complexity of the cavity design, the requirement for multiple RF couplers, the close proximity to the second LHC beam pipe and the tight space constraints in the SPS tunnel. This paper highlights some of the key design features of the cryomodule with the results of the associated mechanical and thermal analysis.

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WEPRI046

Commissioning of the ERL Cryomodule on ALICE at Daresbury Laboratory

cryomodule, linac, cryogenics, LLRF

2583

A.E. Wheelhouse, R.K. Buckley, S.R. Buckley, P.A. Corlett, L.S. Cowie, P. Goudket, A.R. Goulden, L. Ma, P.A. McIntosh, A.J. Moss, S.M. Pattalwar
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The ERL cryomodule with two identical 7-cell, 1.3 GHz cavities developed as part of a international collaborative program has been installed in the linac stage on the ALICE (Accelerators and Lasers in Combined Experiments) facility at Daresbury Laboratory replacing the existing 9-cell cryomodule. The cavities have been cooled to 2 K and commissioning of the cryomodule is underway. This paper describes the conditioning and the characterisation tests performed on the two superconducting RF cavities.

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WEPRI047

UK Industrial Development of Manufacturing Techniques for Superconducting RF Cavities

niobium, electron, superconducting-RF, PLC

2586

A.E. Wheelhouse, R.K. Buckley, L.S. Cowie, P. Goudket, A.R. Goulden, P.A. McIntosh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.R. Everard, N. Shakespeare
Shakespeare Engineering, South Woodham Ferrers, Essex, United Kingdom

An STFC Innovation Partnership Scheme (IPS) grant, funding Daresbury Laboratory and Shakespeare Engineering Ltd to develop the capability to fabricate, process and test a 9-cell 1.3 GHz superconducting RF cavity in support of enabling UK industry to address the large potential market for superconducting RF structures. At the heart of the development are the repeatability and the reproducibility of the manufacturing process in an effort to reduce the costs. Effort has been spent on developing the techniques to fabricate the niobium half cells and the beam pipes and this paper discusses the manufacturing processes and the results obtained.

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WEPRI048

Testing and Dressed Cavity Design for the HL-LHC 4R Crab Cavity

HOM, luminosity, cryomodule, dipole

2589

B.D.S. Hall, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
R. Calaga, S. Calatroni, E. Jensen, A. Macpherson, M. Navarro-Tapia
CERN, Geneva, Switzerland
T.J. Jones, N. Templeton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
A.J. May, P.A. McIntosh, S.M. Pattalwar, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The High luminosity upgrade to the LHC (HL-LHC) calls for crab cavities to reduce the luminosity loss due to the crossing angle and help provide luminosity levelling. The 4 Rod Crab Cavity (4RCC) is one of three proposed options under consideration. A bare cavity has been prototyped and has undergone recent vertical tests and the results are presented. The dressed cavity includes a power coupler, a lower order mode coupler and two HOM couplers will be presented and discussed.

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WEPRI049

Optimization of Window Position on Diamond SCRF Cavities

operation, coupling, 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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WEPRI050

Development and Test Results of a Quasi-waveguide Multi-cell Resonator

niobium, cathode, impedance, HOM

2595

Z.A. Conway, A. Barcikowski, S.M. Gerbick, M. Kedzie, M.P. Kelly, J.S. Kerby, S.H. Kim, S.V. Kutsaev, R.C. Murphy, A. Nassiri, P.N. Ostroumov, T. Reid, T.L. Smith, A. Zholents
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Offices of Nuclear Physics and Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
This paper reports the successful fabrication and test results of a novel 2815 MHz superconducting deflecting cavity operating in a TE-mode trapped in a quasi-waveguide structure with extremely high shunt impedance. The waveguide structure of this cavity allows for the free propagation of all higher order modes (HOMs) out of the cavity via the beam ports, eliminating the need for HOM dampers inside the cavity when operated with high beam current. The absence of HOM dampers greatly simplifies the cavity fabrication and operation at cryogenic temperatures. This cavity with its high shunt impedance is ideal for the spatial rotation of short bunches in a small physical space, a requirement for the generation of sub-picosecond short pulse x-rays in electron storage rings or luminosity upgrades of colliders. Results characterizing the fabrication accuracy and precision, the RF performance at 2 K, and frequency tuning considerations will be discussed here.

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WEPRI051

Results from RF Tests of the First US-built High-gradient Superconducting Cryomodule

cryomodule, SRF, cryogenics, linear-collider

2598

A. Hocker, C.M. Baffes, K. Carlson, B. Chase, D.J. Crawford, E. Cullerton, D.R. Edstrom, E.R. Harms, T. Kubicki, M.J. Kucera, J.R. Leibfritz, J.N. Makara, D. McDowell, O.A. Nezhevenko, D.J. Nicklaus, H. Pfeffer, Y.M. Pischalnikov, P.S. Prieto, J. Reid, W. Schappert, P. Stabile, P. Varghese
Fermilab, Batavia, Illinois, USA

Funding: United States Department of Energy, Contract No. DE-AC02-07CH11359
Fermilab has built a cryomodule comprised of eight 1.3 GHz superconducting RF cavities for use in its Advanced Superconducting Test Accelerator (ASTA) facility. This cryomodule (RFCA002) was intended to achieve the International Linear Collider (ILC) “S1” goal of demonstrating an average accelerating gradient of 31.5 MV/m, and is the first of its kind built in the United States. The module has been cooled down and operated without beam at ASTA in order to assess its performance. The results from these tests are presented here.

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WEPRI052

SRF Systems for ASTA at Fermilab

cryomodule, operation, SRF, electron

2601

E.R. Harms, C.M. Baffes, K. Carlson, B. Chase, D.J. Crawford, E. Cullerton, D.R. Edstrom, M. Geynisman, A. Hocker, A.L. Klebaner, M.J. Kucera, J.R. Leibfritz, J.N. Makara, D. McDowell, S. Nagaitsev, O.A. Nezhevenko, D.J. Nicklaus, H. Pfeffer, Y.M. Pischalnikov, P.S. Prieto, J. Reid, W. Schappert, P. Stabile, P. Varghese
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The Advanced Superconducting Test Accelerator (ASTA) at Fermilab now being commissioned is comprised of a number of superconducting RF systems including single-cavity cryomodules and a TESLA/ILC style 8-cavity cryomodule. Two of them, 'Capture Cavity 2' and 'Cryomodule 2', have been cooled to 2 Kelvin and brought into operation. We provide an overview of the unique characteristics of each of the systems, commissioning experience, and latest results including their respective operating characteristics.

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WEPRI053

Phase Method of Measuring Cavity Quality Factor

simulation, coupling, 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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WEPRI054

Medium Field Q-Slope Studies in Low Beta Resonators

radiation, niobium, controls, operation

2608

O.S. Melnychuk, A. Grassellino, A.I. Sukhanov
Fermilab, Batavia, Illinois, USA

Studies of the phenomenon of Medium field Q-slope (MFQS, 30-80 mT) have been focused predominantly on high beta superconducting cavities. Complementing research on cavity losses with the analysis of low beta cavity data can provide additional insights into the nature of MFQS. We present MFQS measurements of 325MHz β=0.2 single spoke resonators and 650MHz β=0.9 elliptical single cell resonators at vertical test facility at FNAL. We compare our findings with those obtained for high frequency 1.3GHz cavities tested both at the same facility and other laboratories.

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WEPRI057

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

controls, interface, coupling, 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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WEPRI058

Commissioning Status of the Advanced Superconducting Test Accelerator at Fermilab

gun, laser, cryomodule, cathode

2615

J. Ruan, R. Andrews, C.M. Baffes, D.R. Broemmelsiek, K. Carlson, B. Chase, M.D. Church, D.J. Crawford, E. Cullerton, J.S. Diamond, N. Eddy, D.R. Edstrom, E.R. Harms, A. Hocker, A.S. Johnson, A.L. Klebaner, M.J. Kucera, J.R. Leibfritz, A.H. Lumpkin, J.N. Makara, S. Nagaitsev, O.A. Nezhevenko, D.J. Nicklaus, L.E. Nobrega, P.S. Prieto, J. Reid, J.K. Santucci, G. Stancari, D. Sun, M. Wendt, S.J. Wesseln
Fermilab, Batavia, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The Advanced Superconducting Test Accelerator (ASTA) is under construction at Fermilab. This accelerator will consist of a photo-electron gun, injector, ILC-type cryomodules, and multiple downstream beam-lines. Its purpose is to be a user-based facility for Advanced Accelerator R&D. . Following the successful commissioning of the photoinjector gun, a Tesla style 8-cavity cryomodule and a high gradient capture cavity have been cooled down to 2 K and powered commissioning and performance characterization has begun. We will report on the commissioning status and near-term future plans for the facility.

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WEPRI060

Investigation of Thermocurrents Limiting the Performance of Superconducting Cavities

shielding, niobium, linac, framework

2621

R.G. Eichhorn, C.G. Daly, F. Furuta, A. Ganshin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

As the surface resistance of superconducting cavities approach the theoretical limits parasitic effects limiting the performance came into focus of current research. One of these effects is that the quality factor of a cavity is impacted by the cooldown rate. We will present results from recent investigations on thermocurrents, driven by the temperature difference between the two material interfaces between the superconducting Niobium cavity and its Titanium helium-vessel, leading to the presence of a magnetic field while the cavity transits to the superconducting state.

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WEPRI061

Cornell's Main Linac Cryomodule for the Energy Recovery Linac Project

linac, cryomodule, vacuum, alignment

2624

R.G. Eichhorn, B. Bullock, J.V. Conway, B. Elmore, F. Furuta, Y. He, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, T.I. O'Connel, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Cornell University has been designing and building superconducting accelerators for various applications for more than 50 years. Currently, an energy-recovery linac (ERL) based synchrotron-light facility is proposed making use of the existing CESR facility. As part of the phase 1 R&D program funded by the NSF, critical challenges in the design were addressed, one of them being a full linac cryo-module. It houses 6 superconducting cavities- operated at 1.8 K in continuous wave (CW) mode - with individual HOM absorbers and one magnet/ BPM section. Pushing the limits, a high quality factor of the cavities (2•1010) and high beam currents (100 mA accelerated plus 100 mA decelerated) are targeted. We will present the status of the main linac cryomodule (MLC) fabrication and the findings on the cavity performance and component testing.

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WEPRI062

The Joint High Q0 R&D Program for LCLS-II

cryomodule, linac, SRF, factory

2627

M. Liepe, R.G. Eichhorn, F. Furuta, G.M. Ge, D. Gonnella, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A.C. Crawford, A. Grassellino, A. Hocker, O.S. Melnychuk, A. Romanenko, A.M. Rowe, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA
R.L. Geng, A.D. Palczewski, C.E. Reece
JLab, Newport News, Virginia, USA
M.C. Ross
SLAC, Menlo Park, California, USA

The superconducting RF linac for LCLS-II calls for 1.3 GHz 9-cell cavities with an average intrinsic quality factor Q0 of 2.7·10¹⁰ at 2K and 16 MV/m accelerating gradient. A collaborative effort between Cornell University, FNAL, and JLab has been set up with the goal of developing and demonstrating a cavity treatment protocol for the LCLS-II cavities meeting these specifications. The high Q0 treatment protocol is based on nitrogen doping of the RF surface layer during a high temperature heat treatment. This novel SRF cavity preparation was recently developed at FNAL and shown to result in SRF cavities of very high Q0 at 2K with an increase in Q0 from low to medium fields. N-doped single cell cavities at Cornell, FNAL, and JLab routinely exceed LCLS-II specification. 9-cell N-doped cavities at FNAL achieve an average Q0(T=2K, 16 MV/m) of ≈ 3.4·10¹⁰ with an average quench field of ≈ 19 MV/m, meeting therefore overall with good margin the LCLS-II specification.

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WEPRI063

Flux Trapping in Nitrogen-Doped and 120 C Baked Cavities

SRF, linac, vacuum, niobium

2631

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

Funding: United States Department of Energy
It is well known that external magnetic fields can cause higher residual resistance in superconducting RF cavities if the field is present during cooldown. However, the effect of cavity preparation and surface mean free path on the resulting residual resistance from magnetic field is less well studied. In this paper, we report on recent studies at Cornell in which two SRF cavities (one nitrogen-doped and one 120oC baked) were cooled through Tc in an applied uniform external magnetic field. Trapped flux and residual resistance were measured for a variety of cooldowns and applied magnetic fields. It was found that the residual resistance due to trapped flux in the nitrogen-doped cavity was three times larger than in the 120oC baked cavity.

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WEPRI064

New Insights into Heat Treatment of SRF Cavities in a Low-pressure Nitrogen Atmosphere

niobium, SRF, vacuum, resonance

2634

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

Funding: United States Department of Energy
Recent results from Cornell and FNAL have shown that superconducting RF cavities given a heat treatment in a nitrogen atmosphere of a few mTorr display an increase in Q0 with increasing accelerating field, opposite to the medium field Q slope usually observed. Three cavities was prepared at Cornell using this method and subsequently tested after different amounts of material removal. Cavity performance and material properties were extracted for each cavity and correlated with material removal. This has given new insights into how material properties and the anti-Q slope depend on cavity preparation.

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WEPRI065

SRF Material Performance Studies using a Sample Host Cavity

niobium, coupling, 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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WEPRI066

Recent Progress in Nb3Sn SRF Cavity Development at Cornell

niobium, SRF, accelerating-gradient, cryogenics

2641

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

Nb₃Sn coatings on niobium SRF cavities have the potential to significantly reduce cryogenic costs due to their extremely small surface resistance (R_s). In this paper, we present new results showing the repeatability of Cornell's fabrication process, which produces high Q₀ cavities that reach medium fields with minimal Q-slope. We also show the results of attempts to smooth RF surfaces and reduce defects via material removal. However, both HF rinsing and centrifugal barrel polishing resulted in strong performance degradation.

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WEPRI067

Multi-Physics Analysis of CW Superconducting Cavity for the LCLS-II using ACE3P

simulation, feedback, operation, vacuum

2645

Z. Li, C. Adolphsen, O. Kononenko, T.O. Raubenheimer, C.H. Rivetta, M.C. Ross, L. Xiao
SLAC, Menlo Park, California, USA

Funding: Work was supported by the U.S. DOE contract DE-AC02-76SF00515 and used the resources of NERSC at LBNL under US DOE Contract No. DE-AC03-76SF00098.
The LCLS-II linac utilizes superconducting technology operating at continuous wave to accelerate the 1-MHz electron beams to 4 GeV to produce tunable FELs. The TESLA 9-cell superconducting cavity is adopted as the baseline design for the linac. The design gradient is approximately 16 MV/m. The highest operating current is 300 μA. Assuming that the RF power is matched at the highest current, the optimal loaded QL of the cavity is found to be around 4·10⁷. Because of the high QL, the cavity bandwidth approaches the background microphonic detuning, and the performance of the cavity is tightly coupled to the mechanical perturbations of the cavity/cryomodule system. The resulting large phase and amplitude variations in the cavity require active feedback to achieve the 0.01% amplitude and phase stability requirements. To understand the cavity RF response and feedback requirements to the microphonics and Lorentz Force detuning, we have developed a simulation model of the RF-mechanical coupled system using parameters obtained with the multi-physics solver ACE3P. We will present the simulation results of the LCLS-II linac under different power feed scenarios and feedback schemes.

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WEPRI068

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

vacuum, scattering, Windows, coupling

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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WEPRI069

Reproducibility of High-Q SRF Cavities by High Temperature Heat Treatment

vacuum, SRF, induction, niobium

2651

P. Dhakal, G. Ciovati, P. Kneisel, G.R. Myneni
JLab, Newport News, Virginia, USA

Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Recent work on high-temperature (> 600 °C) heat treatment of ingot Nb cavities in a customized vacuum furnace for several hours showed the possibility of achieving Q0-values of up to ~5×10¹⁰ at 2.0 K, 1.5 GHz and accelerating gradients of ~20 MV/m. This contribution presents results on further studies of the heat treatment process to produce cavities with high Q0 values for continuous-wave accelerator application. Single-cell cavities of different Nb purity have been processed through few cycles of heat-treatments and chemical etching. Measurements of Q0 as a function of temperature at low RF field and of Q0 as a function of the RF field at or below 2.0 K have been made after each treatment. Measurements by TOF-SIMS of the impurities’ depth profiles were made on samples heat treated with the cavities.

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WEPRI070

Mechanical Properties of Ingot Nb Cavities

SRF, niobium, radio-frequency, network

2654

G. Ciovati, P. Dhakal, P. Kneisel, J.D. Mammosser, J. Matalevich, G.R. Myneni
JLab, Newport News, Virginia, USA

Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
This contribution presents the results of measurements of the resonant frequency and of strain along the contour of a single-cell cavity made of ingot Nb subjected to increasing uniform differential pressure, up to 6 atm. The data were used to infer mechanical properties of this material after cavity fabrication, by comparison with the results from simulation calculations done with ANSYS. The objective is to provide useful information about the mechanical properties of ingot Nb cavities which can be used in the design phase of SRF cavities intended to be built with this material.

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WEPRI073

High Order Modes Survey and Mitigation of the CEBAF C100 Cryomodules

HOM, impedance, cryomodule, survey

2660

J. Guo, M. Stirbet, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: Funding Agency: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Ten new C100 cryomodules have been installed for the CEBAF 12GeV upgrade in the last few years. The high order modes (HOM) of these cryomodules need to be controlled to avoid beam breakup (BBU) instability. We surveyed the HOM for all the 80 cavities of the C100 modules in both the JLab cryomodule test facility (CMTF) and the CEBAF tunnel. Additional measures such as waveguide filters were applied to bring down out of spec modes. In this paper, we will present the HOM survey setup and results. The mitigation measures and their effects will also be discussed.

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WEPRI074

Status of SRF Facilities at SNS

SRF, cryomodule, operation, controls

2663

J. Saunders, R. Afanador, B. DeGraff, C.J. McMahan
ORNL RAD, Oak Ridge, Tennessee, USA
M.T. Crofford, M. Doleans, M.P. Howell, S.-H. Kim, S.W. Lee, T.S. Neustadt, S.E. Stewart, W.H. Strong
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
As a part or an ongoing process to maintain and improve the performance of its Superconducting Linac (SCL) the Spallation Neutron Source (SNS) is building facilities for processing and testing Superconducting Radio Frequency (SRF) cavities. Recently both a High Pressure Rinse (HPR) tool and a Vertical Test Apparatus (VTA) have been built and commissioned. The HPR is a commercially fabricated piece of equipment which is customized for the SNS application. The VTA was specified, designed and developed by the SNS. This paper will outline the design features as well as the commissioning results for both systems.

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WEPRI075

A Compact Beam Spreader using RF Deflecting Cavities for the LCLS-II

dipole, septum, electron, HOM

2666

S.U. De Silva, J.R. Delayen, R.G. Olave
ODU, Norfolk, Virginia, USA
L.R. Doolittle, M. Placidi, A. Ratti
LBNL, Berkeley, California, USA
P. Emma
SLAC, Menlo Park, California, USA

The LCLS-II project currently under development is designed to accelerate electron bunches up to 4 GeV and transport them to one of two FEL undulators located more than 2 km downstream of the end of the LCLS-II linac. The upgrade requires a spreader system to separate the baseline electron bunches and transport them to two undulator lines or a local dump. Fast bipolar kickers (FK) or transverse electric rf deflectors (RFD) are considered as fast-switching devices (FSD). In the RFD approach described here three design options operating at 325 MHz are studied including a superconducting rf-dipole cavity, a normal conducting rf-dipole cavity, and a normal conducting 4-rod cavity. Optional compact splitting schemes involving a combination of vertical and horizontal initial deflections are addressed.

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WEPRI076

Higher Order Mode Damping in Superconducting Spoke Cavities

HOM, damping, higher-order-mode, superconductivity

2669

C.S. Hopper, J.R. Delayen
ODU, Norfolk, Virginia, USA

Parasitic higher order modes (HOMs) can be severely detrimental to the performance of superconducting cavities. For this reason, the mode spectrum and beam coupling strength must be examined in detail to determine which modes must be damped. One advantage of the spoke cavity geometry is that couplers can be placed on the outer body of the cavity rather than in the beam line space. We present an overview of the HOM properties of spoke cavities and methods for suppressing the most harmful ones.

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WEPRI077

Cryogenic Test of a 750 MHz Superconducting RF Dipole Crabbing Cavity*

radiation, simulation, cryogenics, electron

2672

A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA
A. Castilla, J.R. Delayen, H. Park
JLab, Newport News, Virginia, USA
A. Castilla
DCI-UG, León, Mexico

Funding: *Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. With resources of NERSC, under U.S. DOE contract No. DE-AC02-05CH11231.
A superconducting rf dipole cavity has been designed to address the challenges of a high repetition rate (750 MHz), high current for both electron/ion species (0.5/3 A per bunch), and large crossing angle (50 mrad) at the interaction points (IPs) crabbing system for the Medium Energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The cavity prototype built at Niowave, Inc. has been tested at the Jefferson Lab facilities. In this work we present a detailed analysis of the prototype cavity performance at 4 K and 2 K, corroborating the absence of hard multipacting barriers that could limit the desired transverse fields, along with the surface resistance (R_s) temperature dependency.

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WEPRI078

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

coupling, 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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WEPRI081

Mechanical Design of the 704 MHz 5-cell SRF Cavity Cold Mass for CeC PoP Experiment

SRF, cryomodule, experiment, electron

2678

J.C. Brutus, S.A. Belomestnykh, I. Ben-Zvi, Y. Huang, V. Litvinenko, I. Pinayev, J. Skaritka, L. Snydstrup, R. Than, J.E. Tuozzolo, W. Xu
BNL, Upton, Long Island, New York, USA
T.L. Grimm, R. Jecks, J.A. Yancey
Niowave, Inc., Lansing, Michigan, USA

Funding: * Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
A 5-cell SRF cavity operating at 704 MHz will be used for the Coherent Electron Cooling Proof of Principle (CeC PoP) system under development for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The CeC PoP experiment will demonstrate the new technique of cooling proton and ion beams that may increase the beam luminosity in certain cases, by as much as tenfold. The 704 MHz cavity will accelerate 2 MeV electrons from a 112 MHz SRF gun up 22 MeV. Novel mechanical designs, including a super fluid heat exchanger, helium vessel, vacuum vessel and tuner mechanism are presented. Structural and thermal analysis, using ANSYS were performed to confirm the mechanical tuning system structural stability. This paper provides an overview of the design, the project status and schedule of the 704 MHz 5-cell SRF for CeC PoP experiment.

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WEPRI106

Design of Cryomoudles for RAON

cryomodule, vacuum, linac, ion

2746

Y. Kim, C. Choi, H.M. Jang, Y.W. Jo, H.J. Kim, W.K. Kim, M. Lee
IBS, Daejeon, Republic of Korea

The accelerator will be built in Korea called RAON has four kinds of superconducting cavities such as QWR, HWR1, SSR1 and SSR2, and those cavities are operating in 2 K. The fabrication design for the SSR1 and SSR2 cryomodules are reported in this paper. The issues included in the paper are thermal and structural analysis results for the components such thermal shield, support post, two phase pipe, and so on.

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WEPRI107

Fundamental Thermal Analysis for Cryogenic System Design

radiation, cryogenics, cryomodule, electron

2749

H. Kim, D. Jeon, W.K. Kim, G.-T. Park, I. Shin, J.H. Shin, S.W. Yoon
IBS, Daejeon, Republic of Korea

Non-uniform temperature distribution, surface roughness, and superfluid helium level change between 2K dewar and cryomodule are most important thermal analyses in designing cryogenic system. Effective temperature for non-uniform temperature distribution is defined. Thermal radiation property from surface roughness which is related to fractional dimension is investigated. Superfluid helium level change between 2K dewar and cryomodule is shown as a function of temperature difference. Our research can be useful thermal analyses for cryogenic system design.

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WEPRI110

The HNOSS Horizontal Cryostat and the Helium Liquefaction Plant at FREIA

cryogenics, operation, vacuum, linac

2759

R. Santiago Kern, T.J.C. Ekelöf, K.J. Gajewski, L. Hermansson, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden
P. Bujard, N.R. Chevalier, T. Junquera, J.P. Thermeau
Accelerators and Cryogenic Systems, Orsay, France

A horizontal cryostat to test superconducting cavities and magnets at liquid helium temperatures is installed at FREIA (Facility for REsearch Instrumentation and Accelerator development) at Uppsala University, Sweden. The cryostat allows full testing of superconducting spoke and elliptical accelerating cavities without the need of a specialized cryomodule per cavity. Because horizontal cryostats are custom-built, their number in the accelerator world is very limited. The FREIA horizontal cryostat is one of a kind as it has been designed to be versatile: it is able to house either two ESS double-spoke, or two ESS/TESLA type elliptical cavities, or superconducting magnets or a combination of these with all the ancillary equipment (power couplers, tuners, etc) and test them at the same time, reducing installation time but requiring extra design effort and cryogens supply. In order to achieve this, a helium liquefier with a capacity of 140 l/h delivers liquid helium to the horizontal cryostat while the return gases are directed towards a recovery system, connected in closed loop with the liquefier.

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WEPRI111

Investigation of Moisture Contamination in the Cryogenic System at NSRRC

cryogenics, operation, controls, storage-ring

2762

F. Z. Hsiao, S.-H. Chang, W.-S. Chiou, H.C. Li, T.F. Lin, C.P. Liu, H.H. Tsai
NSRRC, Hsinchu, Taiwan

In NSRRC the helium cryogenic plant began its normal operation in year 2002. Several events of moisture contamination forced the cryogenic plant to cease operation because the cooling performance degraded evidently. After long-term observation we found, through internal inspection of the helium gas buffer tank, maintenance of the compressor station, and warming the superconductive magnet, that moisture contamination occurred. This paper presents the effect of those conditions on the moisture contamination. The solution to decrease the moisture contamination is demonstrated here.

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THXA01

BPMs From Design to Real Measurement

electronics, simulation, operation, vacuum

2774

D. Lipka, S. Vilcins
DESY, Hamburg, Germany

Beam Position Monitors (BPM) are an essential tool for the operation of an accelerator. Therefore BPM systems have to be already included from the beginning in the design of a new machine. This contribution describes the development of a new BPM system up to the operation with a focus on the mechanical design. It includes the collection of the requirements and boundary conditions which defines the kind of BPM system. Following the mechanical designing process is described where simulations are used to predict the signals. These results are input parameters for the design and optimization of the electronics. Several contributions are considered which can modify the BPM signal like feedhroughs, heating due to wake losses, holders, cables and so on. The steps from the design, the prototypes and series production including laboratory and test accelerator measurements up to the commissioning are described as well.

Slides THXA01 [4.844 MB]

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THOAA02

Development of a Low-latency, High-precision, Intra-train Beam Feedback System Based on Cavity Beam Position Monitors

feedback, kicker, FPGA, controls

2783

N. Blaskovic Kraljevic, D.R. Bett, P. Burrows, G.B. Christian, M.R. Davis, Y.I. Kim, C. Perry
JAI, Oxford, United Kingdom

A low-latency, intra-train, beam feedback system utilising a cavity beam position monitor (BPM) has been developed and tested at the final focus of the Accelerator Test Facility (ATF2) at KEK. A low-Q cavity BPM was utilised with custom signal processing electronics, designed for low latency and optimal position resolution, to provide an input beam position signal to the feedback system. A custom stripline kicker and power amplifier, and an FPGA-based digital feedback board, were used to provide beam correction and feedback control, respectively. The system was deployed in single-pass, multi-bunch mode with the aim of demonstrating intra-train beam stabilisation on electron bunches of charge ~ 1nC separated in time by c. 280ns. The system has been used to demonstrate beam stabilisation to below the 100nm level. Results of the latest beam tests, aimed at even higher performance, will be presented.

Slides THOAA02 [2.050 MB]

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THOBB01

Pursuing the Origin and Remediation of Low Q0 observed in the Original CEBAF Cryomodules

cryomodule, shielding, SRF, linac

2828

R.L. Geng, J.F. Fischer, C.E. Reece, A.V. Reilly
JLab, Newport News, Virginia, USA
F.S. He, Y.M. Li
PKU, Beijing, People's Republic of China

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We report on results of a new investigation into the Q0 degradation phenomenon observed in original CEBAF cavities when assembled into cryomodules. As a result, the RF dissipation losses increased by roughly a factor of two. The origin of the degradation, first observed in 1994, has remained unresolved up to current period, despite much effort. Recently, a new investigation has been launched, taking advantage of the latest cryomodule to undergo refurbishment. Systematic measurements are conducted with respect to the magnetic shielding effects of the double-layer shields and the magnetic properties of various components within the inner shield. This resulted in the new discovery of strongly magnetized strut springs as a major source of remnant magnetic flux near a cavity inside of all magnetic shielding. New springs with superior magnetic properties have been found, evaluated and implemented into the current cryomodule. In this contribution, we will review the data accumulated so far. Options for complete Q0 preservation of assembled cavities and possible Q0 remediation for those 330 cavities already installed in CEBAF will be presented.

Slides THOBB01 [16.521 MB]

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THOBB02

Superconducting Cavity Cryomodule Designs for the Next Generation of CW Linacs: Challenges and Options

cryomodule, vacuum, cryogenics, operation

2831

T.H. Nicol, Y.O. Orlov, T.J. Peterson, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Supported by FRA under DOE Contract DE-AC02-07CH11359
The designs of nearly all superconducting RF (SRF) linacs over the last several years, with one notable exception being CEBAF at Jefferson Lab, have assumed pulsed beam operation with relatively low duty factors. These include the XFEL at DESY, the ILC, the original configuration for Project X at Fermilab, as well as several others. Recently proposed projects, on the other hand, including the LCLS-II at SLAC, the newly configured low and medium energy sections for Project X, and FRIB at Michigan State, to name a few, assume continuous wave or CW operation on quite a large scale with ambitious gradients and cavity performance requirements. This has implications in the cavity design as well as in many parts of the overall cryomodule due to higher dynamic heat loads in the cavities themselves and higher heat loads in the input and high-order-mode (HOM) couplers. Piping internal to the cryomodule, the effectiveness of thermal intercepts, the size of integrated heat exchangers, and many other aspects of the overall design are also affected. This paper will describe some of these design considerations as we move toward the next generation of accelerator projects.

Slides THOBB02 [8.388 MB]

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THPRO004

Study of the CLIO FEL in the Far-infrared in a Partially Guided Mode

vacuum, FEL, undulator, simulation

2859

J.-M. Ortega, J.P. Berthet, F. Glotin, R. Prazeres
LCP/CLIO, Orsay, Cedex, France

The infrared free-electron laser offers a large tunability since the FEL gain remains high throughout the infrared spectral range, and the reflectivity of metal mirrors remains also close to unity. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. A solution is to use this chamber as a waveguide by adaptating the radius of curvature of the cavity mirrors to this regime. Then, as has been shown before* a minimum appears in the spectrum that can be produced by the FEL. We discuss the physical mechanism of this particular regime and compare it to experiments using vacuum chambers of different tranverse sizes. A good agreement is found with results of simulations and with a simple analytical formula.
* Analysis of the periodic power gaps observed in the tuning range of FELs with a partial waveguide, R. Prazeres, F. Glotin, J.-M. Ortega, Phys. Rev. STAB12, 010701 (2009)

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THPRO006

Configuration Management in the Series Production of the XFEL Accelerator Modules

cryomodule, controls, status, target

2863

L. Hagge, S. Barbanotti, S. Eucker, A. Frank, K. Jensch, J. Kreutzkamp, D. Käfer, A. Matheisen
DESY, Hamburg, Germany
S. Berry, O. Napoly
CEA/DSM/IRFU, France
C. Cloué, C. Madec, T. Trublet
CEA/IRFU, Gif-sur-Yvette, France

The series production of the superconducting accelerator modules for the European XFEL requires a production rate of one module per week. For this, assembly procedures have to be well-defined and repeatable, and the punctual supply of parts from the contributing institutes has to be assured. Configuration management (CM) has been introduced for clarification of responsibilities and establishing procedures. CM provides unique identification of parts, part status and location tracking, versioning of documentation, and procedures for change control, auditing and handling non-conformities. The configuration database, which is based on DESY’s Engineering Data Management System, contains the entire information which is necessary for assembling the accelerator modules. The content ranges from work instructions how to build a cryomodule up to individual records of all produced parts. Workflow and reports help tracking production progress and establishing production quality. The presentation gives an overview of the CM solution which is in place for the assembly of the XFEL accelerator modules, and reports experience and lessons learned from series production of the first modules.

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THPRO019

Current Status of PAL-XFEL Project

undulator, klystron, linac, quadrupole

2897

H.-S. Kang, K.W. Kim, I.S. Ko
PAL, Pohang, Kyungbuk, Republic of Korea

The PAL-XFEL, a 0.1-nm hard X-ray FEL facility consisting of a 10-GeV S-band linac, is being constructed in Pohang, South Korea. The installation of linac, undulator, and beam line will be completed by 2015. Its building construction is at its peak moment to be completed by December 2014. The major procurement contract was made in 2013 for the critical components of S-band linac modules and hard X-ray undulators. The commissioning will start in January 2016. We hope the first lasing will be achieved in early 2016.

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THPRO031

Short Pulses THz FEL for the Oxford Accelerator Science Laboratory

FEL, radiation, gun, undulator

2934

T. Chanwattana, R. Bartolini, A. Seryi
JAI, Oxford, United Kingdom
R. Bartolini
DLS, Oxfordshire, United Kingdom
E. Tsesmelis
CERN, Geneva, Switzerland

The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a short pulse THz FEL based on a conventional RF accelerator driven by a RF photocathode gun is being investigated. This report presents the concept of the facility, the accelerator physics and FEL studies and engineering integration in the University physics department.

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THPRO042

Field Emission Studies of Heat Treated Mo Substrates

SRF, cathode, gun, electron

2955

R. Barday, A. Jankowiak, T. Kamps, C. Klimm, J. Knobloch, F. Siewert, A. Varykhalov
HZB, Berlin, Germany
S. Lagotzky, G. Müller
Bergische Universität Wuppertal, Wuppertal, Germany
B. Senkovskiy
Technische Universität Dresden, Dresden, Germany

Funding: This work was supported by German Bundesministerium für Bildung und Forschung project 05K13PX2, Land Berlin and grants of Helmholtz Association.
Molybdenum can be used as a substrate for the bi-alkali antimonide photocathodes utilized for the generation of high brightness electron beams in a superconducting radio frequency (SRF) photoinjector cavities. Operation at high field strength is required to obtain a low emittance beam, thus increasing the probability of field emission (FE) from the cathode surface. Usually, substrates are heated in situ before alkali de- position to remove oxide layers from the surface. FE on Mo substrates was measured by means of a field emission scanning microscope (FESM). It turned out that in situ heat treatment (HT) of the Mo surface significantly changes the FE behaviour by activation of new emitters. For a better understanding of the mechanism for enhanced emission after in situ heating a witness Mo sample was investigated using x-ray photoelectron spectroscopy.

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THPRO044

Report on Gun Conditioning Activities at PITZ in 2013

gun, cathode, vacuum, FEL

2962

M. Otevřel, P. Boonpornprasert, J.D. Good, M. Groß, I.I. Isaev, D.K. Kalantaryan, M. Khojoyan, G. Kourkafas, M. Krasilnikov, D. Malyutin, D. Melkumyan, T. Rublack, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
P. Boonpornprasert, S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand
F. Brinker, K. Flöttmann, S. Lederer, B. Marchetti, S. Schreiber
DESY, Hamburg, Germany
Ye. Ivanisenko
PSI, Villigen PSI, Switzerland
M.A. Nozdrin
JINR, Dubna, Moscow Region, Russia
G. Pathak
Uni HH, Hamburg, Germany
D. Richter
BESSY GmbH, Berlin, Germany

Recently three RF guns were prepared at the Photo Injector Test Facility at DESY, location Zeuthen (PITZ) for their subsequent operation at FLASH and the European XFEL. The gun 3.1 is a previous cavity design and is currently installed and operated at FLASH, the other two guns 4.3 and 4.4 were of the current cavity design and are dedicated to serve for the start-up of the European XFEL photo-injector. All three cavities had been dry-ice-cleaned prior their conditioning and hence showed low dark current levels. The lowest dark current level – as low as 60μA at 65MV/m field amplitude – has been observed for the gun 3.1. This paper reports in details about the conditioning process of the most recent gun 4.4. It informs about experience gained at PITZ during establishing of the RF conditioning procedure and provides a comparison with the other gun cavities in terms of the dark currents. It also summarizes the major setup upgrades, which have affected the conditioning processes of the cavities.

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THPRO046

100 MHz RF System as an Alternative for the Iranian Light Source Facility

HOM, storage-ring, operation, emittance

2968

S. Pirani, H. Ghasem, M. Moradi, Kh.S. Sarhadi
ILSF, Tehran, Iran

The Iranian Light Source Facility (ILSF) RF system was conceptually designed based on ILSF requirements for a 3GeV storage ring and 400 mA beam current at 500 MHz RF frequency. The development of HOM damped cavity with simpler structure at 100MHz and advantages of reducing frequency as investigated at MAX Lab, provided an alternative of 100MHz RF system to be explored for ILSF. RF frequency change and its effects on the beam and machine parameters as well as the availability and cost of RF system components have been studied for ILSF. The conceptual design of a 100MHz RF system and the comparison between 500 MHz and 100 MHz RF frequencies are presented in this report. This paper, furthermore, provides details about the 100MHz RF cavity designed by ILSF RF group based on MAX Lab cavity.

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THPRO048

Emittance and Bunch Length Measurement of the Electron Beams from the NSRRC Photocathode Gun

emittance, electron, gun, space-charge

2974

A.P. Lee, M.C. Chou, N.Y. Huang, J.-Y. Hwang, W.K. Lau, C.C. Liang
NSRRC, Hsinchu, Taiwan
P. Chiu, P. Wang
NTHU, Hsinchu, Taiwan
Y. Hao
BNL, Upton, Long Island, New York, USA

A high brightness photo-injector is under development for single pass FEL research at NSRRC. The gun test facility (GTF) equipped with a photocathode rf gun a compensation solenoid, a S-band high power pulse klystron as well as a UV driver laser has been constructed for testing the photocathode rf gun. The gun is fabricated in house and being tested at the GTF. Since the transverse emittance is a key property of the electron beam from the rf gun, multi-slit method is used to characterize the transverse emittance of the electron beam. Another key property of the electron beam is bunch length. An S-band three-cell deflecting cavity is designed to measure the bunch length. The setup and results of emittance measurement as well as the structure design of the deflecting cavity is reported in this contribution.

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THPRO051

Cavity Design for a S-Band Photoinjector RF Gun with 400 Hz Repetition Rate

gun, FEL, cathode, emittance

2983

J.W. McKenzie, L.S. Cowie, P. Goudket, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
T.J. Jones
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
V.V. Paramonov
RAS/INR, Moscow, Russia

As part of the design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory, a high repetition rate S-band photoinjector RF gun is being developed. This gun will be able to operate at up to 400 Hz repetition rate in single bunch mode. We present the initial cavity design including its optimisation for the beam dynamics of CLARA. We also present the initial cooling design for the cavity which will enable the high repetition rates to be achieved.

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THPRO072

Field Parametrisation for the ESS Superconducting Cavities

linac, simulation, space-charge, HOM

3044

T. Lindqvist
Lund University, Lund, Sweden
E. Laface
ESS, Lund, Sweden

Here we present a method for constructing a parametrization of the electric field in the superconducting elliptic cavities of the ESS linac. The parametrization is done by replicating the electric field from measured data using trigonometric and exponential functions. The field generated by the parameters exhibits a mean error of 0.28% ( maximum error of 3.8% and s.t.d. error 1.1%), with the advantage of only taking up a fraction of the required data. The field in the entire cavity is extrapolated by combining the Maxwell equations with the parametrized form of the field. We also present particle simulations based on the parametrization model to showcase some typical accelerator behaviour. Additionally we present a small extension of the parametrization method to also model spoke cavities.

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THPRO073

Longitudinal Acceptance Evaluation from Hamiltonian

linac, simulation, acceleration, lattice

3047

E. Laface
ESS, Lund, Sweden

An RF cavity is designed around a reference particle; if the energy or the phase of a real particle are too far from the reference, the particle is lost. The widest area of energy-phase that allows a particle to be transported by the cavity is called acceptance of the cavity. In simulations the acceptance is evaluated tracking several particles with different energies and phases and marking when a particle is transmitted or lost. This process can be time consuming because of the large amount of tracked particles requested to characterise the cavity acceptance. In this paper we propose an alternative method to evaluate the acceptance studying directly the Hamiltonian associated to the cavity.

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THPRO095

The Design, Construction and Experiments of a RFQ Cold Model at Tsinghua University

rfq, dipole, insertion, experiment

3110

L. Du, Q.Z. Xing, Y. Yang
TUB, Beijing, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China (Major Research Plan Grant No. 91126003 and Project 11175096).
The design, construction and experiments of a cold model of one high-current CW RFQ with ramped inter-vane voltage at Tsinghua University are presented in this paper. The 1-meter-long aluminium cold model is chosen to be the same as the low-energy part of the 3-meter-long RFQ. This cold model will be used mainly for the RFQ field study and education.

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THPRO098

Realistic Modeling of 4-Rod RFQs with CST Studio

rfq, simulation, quadrupole, emittance

3119

S.S. Kurennoy, Y.K. Batygin, E.R. Olivas, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

RFQ accelerators are usually designed and modeled with standard codes based on electrostatic field approximations. There are recent examples when this approach fails to predict the RFQ performance accurately: for 4-rod RFQs 3D effects near the vane ends can noticeably influence the beam dynamics. The same applies to any RFQ where the quadrupole symmetry is broken, e.g., 4-vane RFQ with windows. We analyzed two 201.25-MHz 4-rod RFQs – one recently commissioned at FNAL and a new design for LANL – using 3D modeling with CST Studio. In both cases the manufacturer CAD RFQ model was imported into CST. The EM analysis with MicroWave Studio (MWS) was followed by beam dynamics modeling with Particle Studio (PS). For the LANL RFQ with duty factor up to 15%, a thermal-stress analysis with ANSYS was also performed. The simulation results for FNAL RFQ helped our Fermilab colleagues fix the low output beam energy. The LANL RFQ design was modified after CST simulations indicated insufficient tuning range and incorrect output energy; the modified version satisfies the design requirements. Our PS results were confirmed by multi-particle beam-dynamics codes that used the MWS-calculated RF fields.

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THPRO102

Generation of RF Frequency and Phase References on the FAIR Site

controls, electronics, hardware, acceleration

3131

B. Zipfel, H. Klingbeil, U. Laier, K.-P. Ningel, S. Schäfer, C. Thielmann
GSI, Darmstadt, Germany
U. Hartel, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
D.E.M. Lens
TU Darmstadt, RTR, Darmstadt, Germany

Based on the Bunch Phase Timing System (BuTiS)* local analog radio frequency reference signals (RF references) like the particle revolution frequency and their multiple harmonics will be generated. These references are used to control the phase of the accelerator cavities to altering harmonics of the bunch revolution frequency. Delay or phase shifts from the FAIR-Center to references at the BuTiS endpoints are already compensated by the BuTiS receivers. Phase shifts from the RF reference generators to LLRF electronics can be compensated by controlling the output phases of the DDS modules of the RF references. However phase shift delays of multiple harmonics at the same interconnecting electrical path are not identical at the same time. Configurable electronics** manage phase calibration of the RF references to their endpoints. Calibration may depend on frequency and harmonic of the RF reference, aging as well as on thermal effects. The electrical length and impedance of interconnecting cables for phase control loops can be compensated. This is an important feature, in particular if control loops are switched between different harmonic frequencies.
*B. Zipfel, P. Moritz: Proc. IPAC 2011, San Sebastian
**S. Schäfer, et al.: Proc. IPAC 2013, Shanghai

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THPRO105

MTCA.4 Module for Cavity and Laser Piezo Operation

laser, high-voltage, controls, feedback

3140

K.P. Przygoda, J. Branlard, M. Felber, C. Gerth, M. Heuer, U. Mavrič, P. Peier, H. Schlarb, B. Steffen
DESY, Hamburg, Germany
T. Kozak, P. Prędki
TUL-DMCS, Łódź, Poland

A MicroTCA.4 (MTCA.4) compliant Piezo Driver (DRTM-PZT4)* has been developed to drive piezoelectric-based actuators used in accelerator instrumentation applications. More specifically, it is used for superconducting cavities fine tuning, synchronization of pulsed lasers and stabilization of fiber links. This paper briefly presents the designed system requirements and discusses the main hardware issues. The Piezo Driver performance measurements are also discussed. The first results of the prototype hardware usage for laser locking** to an external RF source and fiber link stabilization are summarized.
*K. Przygoda et all.,“MTCA.4 Compilant Piezo Driver RTM for Laser Synchronization”,MIXDES'13**U. Mavric et. all, "Precision Synchronization of Optical Lasers based on MTCA.4 Electronics", IBIC'13

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THPME002

Delta-Phi Method for the IFMIF-LIPAc SRF-Linac Cavity Tuning

linac, simulation, SRF, focusing

3205

M. Valette, N. Chauvin
CEA/IRFU, Gif-sur-Yvette, France
P.A.P. Nghiem, D. Uriot
CEA/DSM/IRFU, France

In order to achieve the upcoming commissioning of the IFMIF-LIPAc prototype accelerator in Rokkasho, the precision and resolution required for all diagnostics must be determined. These specifications will depend on the precision at which the tuning parameters must be set and finally by the tuning errors that can be tolerated on the beam itself. We will here discuss the use of the ∆φ method to tune the SRF-Linac and the resolution requirements it implies for the BPMs. This method, using a relative time of flight measurement to assess the energy of the beam, has the advantages of allowing setting the beam energy and beam longitudinal focusing at once.

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THPME004

Further R&D for a New Superconducting CW Heavy Ion Linac@GSI

linac, ion, solenoid, heavy-ion

3211

W.A. Barth, S. Mickat
GSI, Darmstadt, Germany
M. Amberg, K. Aulenbacher, V. Gettmann
HIM, Mainz, Germany
F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany

A low energy beam line (1.4 MeV/u) behind the GSI High Charge State Injecor will provide cw-heavy ion beams with high beam intensity. It is foreseen to build a new cw-heavy ion-linac for post acceleration up to 7.3 MeV/u. In preparation an advanced R&D program is defined: The first linac section (financed by HIM and partly by HGF-ARD-initiative) comprising a sc CH-cavity embedded by two sc solenoids will be tested in 2014/15 as a demonstrator. After successful testing the construction of an advanced cryomodule comprising four rf cavities is foreseen. As an intermediate step towards an entire cw-linac the use of a double of two CH-cavities is planned: Ashort 5 cell cavity should be mounted directly behind the demonstrator cavity inside a short cryostat. The design of the cw linac based on shorter sc CH-cavities would minimize the overall technical risk and costs. Besides with this cavity an optimized operation of the whole linac especially with respect to beam quality could be achieved. Last but not least the concept of continuous energy variation applying phase variation between the two cavities with constant beta profile could be tested.

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THPME005

Optimization of an IH-cavity based High Energy Heavy-ion Linac at GSI

linac, emittance, ion, brilliance

3214

A. Orzhekhovskaya, G. Clemente, L. Groening, S. Mickat, B. Schlitt
GSI, Darmstadt, Germany

A new high energy heavy-ion injector (HE-Linac) for the FAIR project was proposed as replacement for the existing post-stripper linac at the GSI UNILAC. Six 10⁸ MHz IH-type drift-tube linac cavities within a total length of about 24 m accelerate the ions (up to U²⁸⁺) from 1.4 MeV/u up to 11.4 MeV/u. Fast pulsed quadrupole triplet lenses are used for transverse focusing in between the IH cavities. The optimization of the HE linac with respect to the emittance growth reduction is investigated.

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THPME010

A 325 MHz High Gradient CH – Test Cavity for β=0.16

linac, operation, focusing, DTL

3229

A. Almomani, U. Ratzinger
IAP, Frankfurt am Main, Germany

Funding: BMBF, contract no. 05P12RFRB9
This pulsed linac activity aims on compact designs, which means a considerable increase in voltage gain per meter. At IAP – Frankfurt, a CH – cavity was developed for these studies, where mean effective accelerating fields well above 10 MV/m are expected at 325 MHz, β=0.164. This cavity is developed within a funded project. Currently, the cavity is under construction and expected to be ready for copper plating in autumn 2014. The results might influence the rebuilt of the UNILAC – Alvarez section, which aims on achieving the beam intensities specified for the GSI – FAIR project. The new GSI 3 MW Thales klystron test stand will be very important for these investigations. Detailed investigations for two different types of copper plating can be performed on this cavity. In this work, the status of the cavity fabrication will be presented. Moreover, low temperature operation of copper cavities is discussed for the case of very short RF pulses.

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THPME011

First Coupled CH Power Cavity for the FAIR Proton Injector

linac, proton, coupling, 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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THPME017

Electromechanical Analysis of SCDTL Structures

coupling, 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

coupling, linac, proton, 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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THPME020

Local Compensation-rematch for the C-ADS Accelerator Element Failures with Space Charge

solenoid, emittance, focusing, linac

3259

B. Sun, C. Meng, J.Y. Tang, F. Yan
IHEP, Beijing, People's Republic of China

In order to achieve the required reliability and availability for the C-ADS accelerator, a fault tolerance design is pursued. The effects of cavity and solenoid failure in different locations have been studied and the schemes of compensation by means of local compensation have been investigated. After one cavity failure, by adjusting the settings of the neighbouring cavities and the focusing elements we can make sure that the Twiss parameters and energy are approximately recovered to that of the nominal ones at the matching point. However, the compensation work above is based on the TraceWin code, which has not considered the phase compensation, a code based on MATLAB is under developing to compensate the arrival time at the matching point that the linear space charge effect has also considered.

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THPME021

Designs of High-intensity Proton Linacs with Non-equipartitioning

linac, emittance, proton, accelerating-gradient

3262

C. Meng, Z. Li, S. Pei, B. Sun, J.Y. Tang, F. Yan
IHEP, Beijing, People's Republic of China
R. Garoby, F. Gerigk, A.M. Lombardi
CERN, Geneva, Switzerland

Superconducting technology is playing more and more important roles in high-power proton linacs. Periodic phase advance less than 90 degrees and equipartitioning design are considered very important principles in linac design. Due to the very high construction and operation costs, it is very important in optimizing the design to lower the costs. In usual, the longitudinal emittance is larger from the front-end, thus the transverse phase advance is designed to have a larger value. However, with the technical advancement, higher accelerating field can be obtained. In order to take this advantage, it is of much interest in increasing the longitudinal phase advance to shorten the linac or reduce the cost. In this paper, we present the design method that keeping the longitudinal phase advance as large as possible but smaller than 90 degree to maximize the use of the available accelerating gradient. Even though this method does not observe the equipartitioning condition, we can also obtain very good beam dynamics results by placing the tunes in resonant-free regions. In this paper, the design and simulation results by applying this method to the SPL and China-ADS linac will be present.

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THPME022

Recent Progress of the SSC-LINAC RFQ

rfq, linac, operation, pick-up

3265

G. Liu, J.E. Chen, S.L. Gao, Y.R. Lu, Z. Wang, X.Q. Yan, K. Zhu
PKU, Beijing, People's Republic of China
H. Du, Y. He, P. Jiang, X.N. Li, Z.S. Li, J.X. Wu, J.W. Xia, Y.Q. Yang, X. Yin, Y.J. Yuan, X.H. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: NFSC(11079001)
The project of SSC-LINAC RFQ has important progresses in the past year. The machine has been moved to the Institute of Modern Physics in the first season of 2013. The cavity measurement including tests of RF performance and field distribution is carried out again in the laboratory. The Q0 is 6440, and the unflatness of the electric field in longitudinal is ±2.5%. The results demonstrated a good agreement with simulation. The RF and beam commissioning of the RFQ has been carried out in the first half of 2014. The duty factor rose from 5% to CW gradually. By now, the cavity has been operated with 35 kW on CW mode. The measurement of the bremsstrahlung spectrum reveals that the 35 kW power is needed to generate the 70 kV inter-vane voltage. The beam transmission efficiency and energy spread has been obtained in beam commissioning by accelerating 16O⁵⁺ and 40Ar⁸⁺ beams. The efficiency of 40Ar⁸⁺ is as high as 94%, and the output energy is 142.78 keV/u. All the processes and results of the experiments will be discussed in details.

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THPME024

Cooling Design for the FRIB RFQ Cavity at Michigan State University

rfq, simulation, operation, linac

3271

J. Zeng, L. Du, X. Guan, Q.Z. Xing, S.X. Zheng
TUB, Beijing, People's Republic of China
W.Q. Guan, J. Li
NUCTECH, Beijing, People's Republic of China

Funding: Work supported by the Major Research plan of the National Natural Science Foundation of China (Grant No. 91126003)
We present, in this paper, the cooling design for the Radio Frequency Quadrupole (RFQ) cavity of the Facility for Rare Isotope Beams (FRIB) at Michigan State University. The locations and radius of the cooling passages are optimized, which exist in the five-meter-long copper cavity, tuners, dipole-mode stabilizing rods and end-plates. A three-dimensional RF, thermal, and structural analysis by ANSYS has been performed to carry out the design and verify that the present design can meet the requirement for water velocity, stress, deformation and frequency shift.

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THPME025

Low Power Test of a Hybrid Single Cavity Linac

rfq, linac, ion, injection

3274

L. Lu, Y. He, Q. Jin, C.X. Li, G. Pan, A. Shi, L.B. Shi, L.T. Sun, L.P. Sun, Z.L. Zhang, H.W. Zhao, H. Zhao
IMP, Lanzhou, People's Republic of China
T. Hattori
NIRS, Chiba-shi, Japan
N. Hayashizaki
RLNR, Tokyo, Japan

We fabricated and assembled a hybrid single cavity (HSC) linac which is formed by combining a radio frequency quadrupole (RFQ) structure and a drift tube (DT) structure into one interdigital-H (IH) cavity. ]. The HSC linac was designed as an injector for a cancer facility and was able to be used as a neutron source for boron neutron capture therapy. The injection method of the HSC linac used a direct plasma injection scheme (DPIS), which is considered to be the only method for accelerating a high current heavy ion beam produced by a laser ion source. The input beam current was designed to be 20 mA, which could be produced by a laser ion source. According to the simulations and calculations, the HSC linac could accelerate a 6-mA C⁶⁺, beam which satisfies the particle number criteria for cancer therapy use (10⁸~9 ions/pulse). Details of the measurements and evaluations of the assembled HSC linac, and details of a DPIS test using a laser ion source are reported in this paper.

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THPME027

Development of the injector II RFQ for China ADS project

rfq, acceleration, linac, proton

3280

Z.L. Zhang, Y.H. Guo, Y. He, H. Jia, C.X. Li, Y. Liu, L. Lu, G. Pan, A. Shi, L.B. Shi, L.P. Sun, W.B. Wang, X.W. Wang, J.X. Wu, Q. Wu, X.B. Xu, B. Zhang, J.H. Zhang, H.W. Zhao, T.M. Zhu
IMP, Lanzhou, People's Republic of China
M.D. Hoff, A.R. Lambert, D. Li, J.W. Staples, S.P. Virostek
LBNL, Berkeley, California, USA
C. Zhang
GSI, Darmstadt, Germany

As one of the main components of the injector II of China ADS LINAC project, an RFQ working at 162.5MHz is used to accelerate proton beams of 15mA from 30 keV to 2.1 MeV. The four vane RFQ has been designed in collaboration with Lawrence Berkeley National Laboratory and built at the workshop of the Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS). Low power test of the cavity have been completed, and it shows the field flatness is within ±1% and the unloaded Q is 12600. RF conditioning has been completed, results of preliminary beam test show the output beam energy is 2.16 MeV with energy spread of 3.5% and the transmission efficiency is 97.9%. Continuous wave (CW) beam of 2.3 mA has been accelerated for more than one hour.

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THPME030

Beam Dynamics and Accelerating Cavity Electrodynamics' Simulation of CW 2 MeV Proton RFQ

rfq, linac, simulation, Windows

3286

S.M. Polozov, A.E. Aksentyev, T. Kulevoy
MEPhI, Moscow, Russia

The CW proton linac has a number of important applications; serving as the initial part of a high-energy, high-power linac for an accelerator-driven system is the main of them. Its CW operation mode and a 5-10 mA beam current, however, are limiting factors for the accelerating field. The surface field should not exceed the Kilpatrick field by more than 1.2-1.5 times. This limitation leads to the increase in linac length and beam bunching complexity. The first results of a 2 MeV, 5 mA, CW RFQ, designed for the operating frequency of 162 MHz, are discussed. Beam dynamics simulation results, obtained by using the BEAMDULAC-RFQ code*, are presented. The electrodynamics of the accelerating structure based on the four-vane cavity is discussed. The accelerating cavity design uses coupling windows as was proposed earlier **, but with windows of an elliptical form. Such form allows for better separation of quarupole and dipole modes.
* S.M. Polozov. Problems of Atomic Science and Technology. Series: Nuclear Physics Investigations, 3 (79), 2012, p. 131-136.
** V.A. Andreev. Patent US5483130, 1996.

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THPME031

Beam Dynamics Simulation in SC Linac for the Proton Radiotherapy

linac, simulation, proton, focusing

3289

S.M. Polozov, I.A. Ashanin, A.V. Samoshin
MEPhI, Moscow, Russia

Superconducting linear accelerators based on short independently phased SC cavities are widely used today in ADS and FRIB. Such accelerator can be useful as proton therapy beam source*. The accelerator general layout to accelerate proton beam at the energy range 2-240 MeV will detail in this report. Obviously, in this linac will always violate the principle of synchronicity when the synchronous particle velocity is equal to the phase velocity of the accelerating wave and a slipping of particles relative to the accelerating wave. The beam dynamics simulation shows that linac should consist of four groups of identical cavities. Cavities should have phase velocities as βg=0.1, 0.18, 0.3 and 0.49 respectively. The choice of optimum parameters of accelerating cavities and focusing magnets will discussed and the beam dynamics simulation results will presented.
*S.M. Polozov, A.V. Samoshin. Proc. of LINAC’12, pp. 633-635

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THPME038

Low Power RF Characterization of ESS Bilbao RFQ Cold Model

rfq, dipole, pick-up, quadrupole

3308

N. Garmendia, I. Bustinduy, O. González, P.J. González, I. Madariaga, L. Muguira, J.L. Muñoz
ESS Bilbao, Zamudio, Spain
A.V. Vélez
HZB, Berlin, Germany

In order to test both the design and manufacturing procedures of the final ESS-Bilbao RFQ, a 1 meter long RFQ Cold Model, including a longitudinal vane modulation, has been manufactured in aluminium. Low power RF measurements have been performed to obtain the main figures of merit of the cavity, including: frequency spectrum, coupling and quality factors, tuning range, RF sealing effect and the accelerating field profile. The experimental and simulated results are explained and analyzed.

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THPME039

Requirements for ESS Superconducting Radio Frequency Linac

linac, cryomodule, SRF, cryogenics

3311

C. Darve, M. Eshraqi, D.P. McGinnis, S. Molloy, E. Tanke
ESS, Lund, Sweden

The European Spallation Source (ESS) is a pan-European project. It will be built by at least 17 European countries, with Sweden and Denmark as host nations. The Superconducting Radio-Frequency (SRF) linac is composed of one section of spoke cavity cryomodules (352.21 MHz) and two sections of elliptical cavity cryomodules (704.42 MHz). These cryomodules contain niobium SRF cavities operating at 2 K. Following a redesign of its accelerator, SRF linac design shall comply with a new set of requirement, like an increase of the beam current from 50 mA to 62.5 mA and an increase of the peak electrical surface field from 40 MV/m to 45 MV/m. Requirements and the main disciplines needed to construct this portion of the linac are presented.

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THPME047

Sorting in the ESS

linac, beam-losses, emittance, simulation

3329

S. Peggs, E. Laface, E. Sargsyan, R. Zeng
ESS, Lund, Sweden

Sorting optical elements has significant potential during the construction of superconducting linacs like the ESS, in the same way that it has proved to be very effective in circular accelerators like RHIC and the LHC. In the linac domain, the elements of primary interest are cavities and cryomodules, instead of the magnets (of all sorts) that are routinely sorted in circular accelerators. Multiple cavities can be sorted to optimise individual cryomodules, and cryomodules can be sorted into optimised locations within the tunnel. Different sorting strategies are discussed and preliminarily evaluated in this paper. Central to the evaluation is the identification of goal (or penalty) functions that are maximised (or minimised), and which can be rapidly quantified by simulation. Also crucial is the availability of a modeling system that is realistic in its complex representation of the linac, and which can easily be modified and developed.

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THPME053

Cost Rationales for an SRF Proton Linac

linac, proton, hardware, SRF

3349

F. Marhauser
Muons, Inc, Illinois, USA

Rationales to assess and minimize costs for a Superconducting Radio Frequency (SRF) proton linac are outlined. Operating frequency, velocity profile and temperature are regarded as variables when applicable. Hardware plus labor costs for cavities and cryomodules as well as expenditures for facility infrastructures including cryogenic systems, conventional facilities, and relevant subsystems are estimated. The focus is on the assessment of a 10 MW, 1 GeV Continuous Wave (CW) linac for an Accelerator Driven Subcritical Reactor (ADSR)

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THPME054

RF Cavity Design Aspects for a Helical Muon Beam Cooling Channel

Windows, embedded, factory, collider

3352

F. Marhauser, G. Flanagan, R.P. Johnson, S.A. Kahn
Muons, Inc, Illinois, USA
K. Yonehara
Fermilab, Batavia, Illinois, USA

Funding: Work supported under U.S. DOE Grant Application Number DE-SC0006266
A Helical Cooling Channel (HCC) promises efficient six-dimensional ionization cooling of muon beams by utilizing high-pressurized gas as a continuous absorber within a magnetic channel embedding RF cavities. The progress on cavity design, tailored for such a cooling channel, is discussed.

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THPME059

Preparation of the Coupled RFQ-IH-cavity for FRANZ

rfq, DTL, coupling, 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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THPME062

Status of the J-PARC Ring RF Systems

operation, proton, extraction, impedance

3376

M. Yoshii, M. Nomura, T. Shimada, F. Tamura, M. Yamamoto
KEK/JAEA, Ibaraki-Ken, Japan
E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, K. Takata, M. Toda
KEK, Ibaraki, Japan
A. Schnase
GSI, Darmstadt, Germany

The high intensity proton accelerator complex (J-PARC) consists of the Linac, the 25Hz rapid cycling synchrotron (RCS) and the 50GeV main synchrotron (MR). During the long shutdown of 2013, the Linac energy was upgraded from 181MeV to the design value of 400MeV. In the RCS, we have installed the last 12th RF system. In operation from January 2014, beam commissioning aimed at 1 MW operation will be started. In the MR, the upgrade plan of the beam power, realizing by raising the repetition, has been started. For this reason the accelerating voltage must be increased, and all MR RF systems will be replaced with more efficient systems. A new magnetic alloy material (FT3L) has been developed. Manufacturing of the FT3L accelerating cavities has proceeded. It becomes possible to increase the accelerating voltage from 280 kV to 540 kV, using the new cavities in combination with the existing RF power supplies. We have started the developments of a 2nd harmonic system loaded with air-cooled FT3L cores and a high-Q VHF cavity system, too. Both systems are used for longitudinal dilution increase the bunching factor of the circulating high intensity proton beam.

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THPME065

Beam Test of the CERN PSB Wide-band RF System Prototype in the J-PARC MR

feedback, impedance, beam-loading, extraction

3385

F. Tamura
JAEA/J-PARC, Tokai-mura, Japan
K. Hasegawa, C. Ohmori, M. Yoshii
KEK, Tokai, Ibaraki, Japan
M.M. Paoluzzi
CERN, Geneva, Switzerland

In the framework of the LHC Injectors Upgrade project (LIU), a complete replacement of the existing narrow-band rf systems of CERN PSB with wide-band magnetic alloy (MA) loaded rf systems is in progress. A single gap MA loaded rf system prototype, which uses solid-state power amplifier and includes fast rf feedback for beam loading compensation, has been installed in the J-PARC MR to investigate the system behavior with high intensity proton beams. We report the wake voltage measurement results with and without fast rf feedback. In addition to the fast feedback, the rf feedforward method is under consideration to compensate the heavy beam loading more effectively. Preliminary beam test results with feedforward are also presented.

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THPME080

Reflective Streak Camera Bunch Length Measurements at the Australian Synchrotron

optics, storage-ring, impedance, synchrotron

3421

M.J. Boland, Y.E. Tan
SLSA, Clayton, Australia
T.M. Mitsuhashi
KEK, Ibaraki, Japan

The bunch length of the 3 GeV electron storage ring at the Australian Synchrotron has been measured using reflective input optics feeding a streak camera. An Offner optical design was employed to reduce the chromatic broadening of the input optics of the streak camera. Using the reflective input optics the bunch length is measured to be 15% shorter than with the refractive input optics. The measured bunch length is now in good agreement with the model of the storage ring and the values are being used for calibration, monitoring and optimisation of the machine. The results of studies to characterise the streak camera shall also be presented.

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THPME100

The Mechanical Design of the BPM Inter-tank Section for P-linac at FAIR

linac, proton, impedance, pick-up

3474

M.H. Almalki, R. M. Brodhage, P. Forck, W. Kaufmann, O.K. Kester, P. Kowina, T. Sieber
GSI, Darmstadt, Germany
M.H. Almalki, R. M. Brodhage, O.K. Kester
IAP, Frankfurt am Main, Germany
M.H. Almalki
KACST, Riyadh, Kingdom of Saudi Arabia
J. Balaguer
CEA/IRFU, Gif-sur-Yvette, France
P. Girardot, C.S. Simon
CEA/DSM/IRFU, France

At the planned Proton LINAC at the FAIR facility, four-fold button Beam Position Monitor (BPM) will be installed at 14 locations along the 30 m long FAIR p-LINAC. The LINAC comprises of crossbar H-mode (CH) cavity to accelerate a 70 mA proton beam up to 70 MeV at frequency of 325 MHz. At four locations, the BPMs will be an integral part of the inter-tank section between the CCH and CH cavities within an evacuated housing. As the BPM centre is only 48 mm apart from the upstream cavity boundary, the rf-background at the BPM position, generated by the cavity must be evaluated. In this paper the mechanical design of the BPM for the inter-tank section is presented and the rf-noise at the BPM location is discussed.

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THPME101

Considerations for a Cavity-Based Position-Sensitive Heavy Ion Detector for the CR at FAIR

impedance, ion, heavy-ion, simulation

3477

X. Chen, P. Hülsmann, Yu.A. Litvinov, F. Nolden, M.S. Sanjari, M. Steck, T. Stöhlker
GSI, Darmstadt, Germany
X. Chen
Heidelberg University, Heidelberg, Germany
Yu.A. Litvinov
MPI-K, Heidelberg, Germany
J. Piotrowski
AGH University of Science and Technology, Kraków, Poland
T. Stöhlker
HIJ, Jena, Germany

Funding: Work funded by the European Commission (PITN-GA-2011-289485), the Alliance Program of the Helmholtz Association (HA216/EMMI), the Helmholtz-CAS Joint Research Group (HCJRG-108), the BMBF (05E12CD2).
The Facility for Antiproton and Ion Research (FAIR) is a complex yet ongoing project which will allow for a broad range of experimental physics programs as well as a variety of material and medical applications. Being a heavy ion storage ring at FAIR, the Collector Ring (CR) is perfectly suitable for scientific investigations on fundamental properties – such as masses and lifetimes – of short-lived radioactive nuclei when it operates in isochronous mode. To fulfill stringent experimental requirements, a compatible heavy ion detector sensitive to beam intensities and positions is highly demanded. In this paper we present a conceptual design of cavity-based Schottky noise pickup to achieve non-destructive detections of stored particles. Computer-aided simulations follow immediately to justify the feasibility of such a design.

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THPME133

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

electron, gun, cathode, coupling

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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THPME138

Dynamic Comparison With XAL and Tracewin Based on the Injector-I of China ADS Test Stand

lattice, linac, cryomodule, solenoid

3572

Y.L. Zhao, P. Cheng, H. Geng, C. Meng, S. Pei, B. Sun, H.J. Wang, B. Xu, F. Yan
IHEP, Beijing, People's Republic of China

The injector scheme I (injector-I) of China ADS test stand is a superconducting Linac which accelerates 10mA beam to 3.2MeV, 5MeV, 10MeV, and then transports it to the dump. The dump line is designed to meet the requirement of beam expansion at the three different energies. The XAL from SNS was selected for the commissioning of China ADS. Because the beam current is so high, the nonlinear space charge force cannot be omitted. As we know, XAL calculates the space charge force with linear resolver. So, whether it could display the beam exactly enough is an important issue to consider. As a preparation for beam commissioning, the virtual accelerator in XAL frame was built and tested. Here in this paper, the envelopes of the 5MeV and 10MeV lattices from general XAL mpx application are shown and compared with the multiparticle tracking code TraceWin.

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THPME140

New Beam Diagnostics and Related Study on HLS Photo-Injector and HLS II

quadrupole, diagnostics, electron, emittance

3578

Q. Luo, H.T. Li, P. Lu, B.G. Sun, K. Tang, J.J. Zheng, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by Natural Science Foundation of China 11005105, 11005106, 11205156 and 11375178.
A team in NSRL is now doing research about small model accelerators and carrying out series of related experiments on HLS photo-injector and HLS II storage ring. Cavity beam multi-parameter monitor system designed for the HLS photocathode RF electron gun consists of a beam position monitor, a beam quadrupole moment monitor and a beam density and bunch length monitor. TM0n0 modes of cavity can be used to work out beam density and bunch length simultaneously. Miniaturization of FEL facilities is now being studied based on results of experiments and theoretical work before. The team also participate in commissioning of HLS II, i.e. measured work points of the new storage ring and did some research on longitudinal bunch-by-bunch feedback system.

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THPME146

Bunch Length Measurement by Using a 2-Cell Superconducting RF Cavity in cERL Injector at KEK

electron, experiment, gun, cathode

3596

J.G. Hwang, E.-S. Kim
Kyungpook National University, Daegu, Republic of Korea
T. Miyajima
KEK, Ibaraki, Japan

The development of future light source and linear colliders require high quality electron beams with short bunch length. The measurement of the bunch length is important technique for future electron machine. In general, the bunch length was measured by using deflecting cavity which has the time dependent transverse electromagnetic field. However, the transverse electric field of 2-cell superconducting RF (SRF) cavity can also provide the correlation between the bunch length and beam size as like the role of the deflecting cavity in bunch length measurement. The deflection strength was calibrated by changing the RF phase and the beam offset because the strength of transverse electric field of RF cavity depends on the phase of RF field and the beam offset in the cavity. We will present new way to measure the bunch length by using 2-cell SRF cavity, which has the acceleration field of 15 MV/m, and the measured result with the bunch length of 3 ps in cERL injector.

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THPME147

The High Position Resolution Cavity BPM Developments and Measurement for ILC Final Focus System

electronics, resonance, alignment, operation

3599

S.W. Jang, J.G. Hwang, E.-S. Kim, L. Lee
KNU, Deagu, Republic of Korea
P. Bambade, O.R. Blanco-García, F. Bogard, S. Wallon
LAL, Orsay, France
Y. Honda, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan

An ultra high position resolution cavity BPM was developed for the final focus system of ATF2, which is a accelerator test facility for ILC final focus system. The main purpose of ATF2 are achievement of 37 nm beam size and nano-meter beam orbit stability at IP(Interaction Point). For these purposes, a few nano meter beam position resolution was required for this cavity BPM, which is called the IP-BPM. The IP-BPM was fabricated 2 blocks of IP-BPM, the first block consists of two cavities in one block and second block consists of single cavity. IP-BPM can measure beam position in vertical and horizontal independently by using rectangular shape single cavity. Three IP-BPMs were installed at ATF IP region inside IP-chamber, and its position resolution was measured. We will present the detailed results on the beam tests.

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THPME148

Beam Dynamics Issues for a Superconducting Linear Accelerator-based High Power Heavy Ion Machine

linac, emittance, ion, proton

3602

J.G. Hwang, E.-S. Kim
Kyungpook National University, Daegu, Republic of Korea
H. Jang, D. Jeon, H.J. Kim, H.J. Kim
IBS, Daejeon, Republic of Korea

The driver linac of RAON heavy ion accelerator based on the superconducting technology, which consists of a 28 GHz ECR ion source, a low energy beam transport line, a RFQ accelerator, a medium energy beam transport line, a low energy linac(SCL1), a charge stripping section and a high energy linac(SCL2), will produce the stable ion beam from proton with 600 MeV to uranium with 200 MeV/u. Many beam dynamics issues such as beam steering effect due to QWR cavities with the peak electric field of 35 MV/m, emittance growth in charge stripper due to the straggling effect, parametric resonance and envelope instability were verified to design the high power heavy ion machine which can produce the high quality beam. In this presentation, we explain our study results for achieving longitudinal acceptance larger than 27 keV/u-ns for the stable operation and minimizing the emittance growth less than 30 % in the superconducting linac for high quality beam at the in-flight target.

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THPME150

Spectrometer for SRF Gun

electron, dipole, simulation, SRF

3608

I.Yu. Vladimirov, V.I. Shvedunov
MSU, Moscow, Russia
T. Kamps, J. Völker
HZB, Berlin, Germany

We report about the design of a spectrometer for energy spectrum measurements of an electron beam generated by a superconducting radio-frequency photoelectron gun (SRF gun), which is under construction at HZB for BERLinPro. The spectrometer shall provide absolute accuracy of energy measurements of about 0.1% and energy resolution about 0.1%. The spectrometer will be also used for single shot phase space measurements in combination with a transverse deflecting cavity.

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THPRI028

Acoustic Spark Localization for the 201 MHz RF Cavity

experiment, Windows, vacuum, software

3828

P.G. Lane, Y. Torun
Illinois Institute of Technology, Chicago, Illinois, USA
E. Behnke, I.Y. Levine
Indiana University South Bend, South Bend, USA
D.W. Peterson
Fermilab, Batavia, Illinois, USA
P. Snopok
IIT, Chicago, Illinois, USA

Funding: Work supported by U.S. Department of Energy
Current designs for muon cooling channels require high-gradient RF cavities to be placed in solenoidal magnetic fields in order to contain muons with large transverse emittances. It has been found that doing so reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields it would be helpful to have a diagnostic tool which can detect breakdown and localize the source of the breakdown inside the cavity. We report here on the experiment setup for localizing sparks in an RF cavity by using piezoelectric transducers and on preparation for data collection on a 201.25 MHz vacuum cavity.

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THPRI030

Progress Towards Completion of the MICE Demonstration of Muon Ionization Cooling

emittance, solenoid, coupling, 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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THPRI032

Study of a RF Gun with a Thermoionic Cathode

gun, injection, simulation, space-charge

3837

A.S. Setty, A.S. Chauchat, D. Fasse, D. Jousse, P. Sirot
Thales Communications & Security (TCS), Gennevilliers Cedex, France

The low energy part of our pre injectors* is made up of a 90 kV DC thermoionic triode gun, followed by a 500 MHz sub harmonic prebuncher and a 3 GHz prebuncher. These two cavities are respectively fed with 500 W, a modulation of ± 25 kV, and 90 W corresponding to a ± 10 kV. The gun grid is modulated within a 500 MHz signal. The initial 1 ns phase extension at the gun level is reduced, at the buncher entry, to 40 ps for 75% of the gun current. This study proposes to replace the gun and the two cavities by a RF gun integrated in a modulated cavity at 200 MHz followed by a drift in order to bunch the beam. This study will compare the beam dynamics simulations for these two cases.
*A. Setty et al, "Design and Construction of Turnkey Linacs as Injectors for Light Sources", Proceedings IPAC 2012, USA, Louisiana, May 2012.

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THPRI033

Design of New Buncher Cavity for Relativistic Electron Gun for Atomic Exploration – REGAE

simulation, emittance, electron, operation

3840

M. Fakhari, H. Delsim-Hashemi, K. Flöttmann, M. Hüning, S. Pfeiffer, H. Schlarb
DESY, Hamburg, Germany
J. Roßbach
Uni HH, Hamburg, Germany

The Relativistic Electron Gun for Atomic Exploration, REGAE, is a small electron accelerator build and operated at DESY. Its main application is to provide high quality electron bunches for time resolved diffraction experiments. The RF system of REGAE contains different parts such as low level RF, preamplifier, modulator, phase shifter, and cavities. A photocathode gun cavity to produce the electrons and a buncher cavity to compress the electron bunches in the following drift tube. Since the difference between the operating mode of the existing buncher and its adjacent mode is too small, the input power excites the other modes in addition to the operating mode which affects the beam parameters. A new buncher cavity is designed in order to improve the mode separation. Furthermore the whole cavity is modeled by a circuit which can be useful especially during the tuning process. Beam dynamics simulations have been performed in order to compare the new designed cavity with the old one which declare that the effects of the adjacent modes on the beam parameters are decreased.

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THPRI035

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

coupling, 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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THPRI040

Study of Geometrical Parameters and their Tolerances in Optimization of Accelerating Cells of Side Coupled Linac

linac, simulation, impedance, electron

3850

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

After choosing the suitable geometry for accelerating cavity, evaluation of geometrical parameters effects on radio frequency characteristics is essential. In this paper after study of priority of geometrical parameters in optimization of accelerating cells of Side Coupled Linac, according to obtained results, new design of s-band accelerating cavity is suggested. By frequency sensitivity study of new dimensions, we can choose best technique to tune the accelerating cavity during magnetic coupling-hole adjustment.

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THPRI041

Twenty Years of Operation of the Elettra RF System

operation, klystron, storage-ring, booster

3853

C. P. Pasotti, M. Bocciai, P. Pittana, M. Rinaldi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Six thousand hours per year is the typical running scheduled time of the user-dedicated Elettra facility and twenty years is a significant amount of operating hours for the RF system. Failure and weak points of the installed equipment is discussed as well as the up-time statistic. The effectiveness of the predictive versus the extraordinary maintenance is presented. The gained operational experience has allowed the planning of the priorities to refit the installed components within a reasonable budget, in compliance with the user-operation time schedule and following the technical need of upgrading to improve the RF system performance.

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THPRI045

Development of a 1.3-GHz Buncher Cavity for the Compact ERL

operation, vacuum, simulation, gun

3866

T. Takahashi, Y. Honda, T. Miura, T. Miyajima, H. Sakai, S. Sakanaka, K. Shinoe, T. Uchiyama, K. Umemori, M. Yamamoto
KEK, Ibaraki, Japan

In a high-brightness injector of the Compact ERL (cERL), a 1.3-GHz buncher cavity is used to compress the electron bunches which are produced at a 500-kV photocathode DC electron gun. An rf voltage required is about 130 kV. To elongate the lifetime of the photocathode of the DC gun which is located beside the buncher cavity, an extremely-low pressure of about 10^-9 Pa is required in the buncher cavity under operating conditions. In order to achieve such low pressures, we have developed a normal-conducting cavity which included several measures to reduce the outgas from the cavity components, together with careful rf designs to avoid any problems due to multipactor discharges or to other problems. With the developed cavity, we achieved a vacuum pressure of about 2·10^-9 Pa under rf operations at an rf voltage of about 100 kV. The buncher cavity was installed in the cERL, and it worked very well; we could demonstrate to compress the bunch length from 10 ps (FWHM) to 0.5 ps (rms) using the buncher cavity.

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THPRI046

Air-cooled Magnetic Alloy Cavity for J-PARC Doubled Rep.-rate Scenario

impedance, injection, acceleration, ion

3869

C. Ohmori, K. Hara, K. Hasegawa, K. Takata, M. Toda, M. Yoshii
KEK, Ibaraki, Japan
M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

The upgrade project of the J-PARC MR (Main Ring) is in progress to deliver the beam power of 750 kW based on doubled repetition-rate scenario. The present RF section will be occupied by 9 sets of new magnetic alloy, FT3L, cavity using the direct water cooling scheme. The direct water cooling requires dedicated high-quality cooling water. These cavities will be used for the fundamental RF for acceleration. The second harmonic RF is necessary to increase the bunch length. This allows to enlarge the beam current, and to relax the space charge effects during the injection. Thanks to the high impedance FT3L, the power loss in the second harmonic RF system becomes moderate. The air cooled cavity is designed to fit in any space in the MR where the dedicated water is not available. This paper reports the design of the second RF system, technical issues to produce the magnetic alloy cores to fit the air cooling, and construction of the system.

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THPRI049

Engineering Design of the RF Input Couplers for C-ADS RFQ

rfq, linac, impedance, operation

3878

L.P. Sun, Y. He, A. Shi, C. Zhang, Z.L. Zhang
IMP, Lanzhou, People's Republic of China

A new coupler with the special ceramic window has been developed at IMP, CAS (Institute of Modern Physics, Chinese Academy of Sciences), operating at 30 kW/162.5 MHz in CW mode for an one-meter prototype cavity, which can provide all kinds of experiences to the real four-meter cavity including EM simulation, power conditioning, cooling consideration and so on. Now, the beam experiments on prototype cavity have been completed and the results show the simulation and the measurements of coupler were in the good agreement. The special bowl-type ceramic window can promote S parameter and reduce sparking risk for beam commissioning stably. A detailed electromagnetic design and measured results of the coupler will be presented in the paper.

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THPRI050

Calculation and Design of the Re-buncher Cavities for the LIPAc Deuteron Accelerator

pick-up, vacuum, operation, beam-transport

3881

D. Gavela, I. Podadera, 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 are necessary for the LIPAc (Linear IFMIF Prototype Accelerator), presently being built at Rokkasho (Japan). They are placed at the Medium Energy Beam Transport (MEBT) line to longitudinally focus a 5 MeV CW deuteron beam. Due to the strong space charge and the compactness of the beamline, the cavity has several space restrictions. In order to minimize the power loss, an IH-type cavity with 5 gaps was selected. It provides an effective voltage of 350 kV at 175 MHz with a power loss of 6.6 kW. First, electromagnetic calculations have been done with HFSS to compute the resonant frequency, the S-parameters, the electric and magnetic field maps, the power losses and the proper geometry for a magnetic input coupler and a pickup probe. Then, a mechanical Ansys model has been used to analyze the stresses and deformations due to vacuum, the cooling circuit and the temperature distribution, taking into account the power losses imported from the electromagnetic model. Finally, the fluid dynamics in the cooling circuits of the stems has been carefully studied.

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THPRI051

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

vacuum, pick-up, coupling, 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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THPRI053

Ferrite Material Characterization in a Static Bias Field for the Design of a Tunable Cavity

simulation, impedance, electromagnetic-fields, solenoid

3890

J. Eberhardt, F. Caspers, C. Vollinger
CERN, Geneva, Switzerland

During the development of ferrite-loaded accelerating cavities, the electromagnetic properties of the dispersive ferrite material need to be known. We describe a coaxial short-circuit measurement technique to measure the complex permeability of toroidal-shaped samples (127mm outer and 70mm inner diameter) that are exposed to an external magnetic bias field. The external magnetic bias field is applied perpendicular to the RF magnetic field. With this method it is possible to characterize the frequency dependence of the permeability for a frequency range of 1-100MHz. The dependence of the permeability on the external magnetic bias is presented for the ferrite G-510 from Trans-Tech Inc. and the material characterization is shown in the same frequency range. The measurement results are verified by simulations of the measurement set-up.

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THPRI054

Permittivity and Permeability Measurement Methods for Particle Accelerator Related Materials

impedance, simulation, resonance, HOM

3893

C. Vollinger, F. Caspers, E. Jensen
CERN, Geneva, Switzerland

For the special requirements related to particle accelerators, knowledge of the different material parameters of dielectrics and other materials are needed in order to carry out simulations during the design process of accelerator components. This includes also properties of magnetically biased ferrites of which usually little information is available about material characteristics, especially in magnetic bias fields. Several methods of measurement are discussed and compared of which some require delicate sample preparation whereas others can work with unmodified material shapes that makes those methods also suited for acceptance checks on incoming materials delivered by industry. Applications include characterization of different materials, as absorbers in which dielectric losses play an increasing role, as well as low frequency measurements on ferrites that are used for tunable cavities. We present results obtained from both broadband and resonant measurements on different materials determined in the same sample holder. Where possible, the results were confirmed with alternative methods.

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THPRI055

The New 118 MHz Normal Conducting RF Cavity for SIAM Photon Source at SLRI

storage-ring, electron, impedance, HOM

3896

N. Juntong, S. Krainara
SLRI, Nakhon Ratchasima, Thailand

The Siam Photon Source (SPS) is the 1.2 GeV second generation light source in Thailand. It is managed by the Synchrotron Light Research Institute (SLRI). The institute is located inside the campus of Suranaree University of Technology (SUT), which is approximately 20 km from the city of Nakhon Ratchasima (or normally called Korat). Korat is 250 km north-east of Bangkok. Two insertion devices (IDs) have been installed in the SPS storage ring during June to August 2013. These IDs require additional electrical field energy from RF cavity to compensate electron energy loss in the storage ring. The existing RF cavity has been pushed to its maximum capability and the new RF cavity is in the procurement process. The design and study of the new RF cavity will be presented. Electromagnetic fields of the cavity are studied together with the effects to electron beam instabilities.

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THPRI056

A New Debunching Cavity for the ISIS H⁻ Injector

vacuum, simulation, DTL, radio-frequency

3899

B.S. Drumm, A.P. Letchford, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
M. Keelan
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

The energy range of the ISIS 70MeV H⁻ injected beam is reduced using an RF debunching cavity. The existing cavity consists of a mild steel vacuum vessel containing a water-cooled copper shell into which RF power is fed. The unit is made up of components designed for the 50 MeV Proton Linear Accelerator (PLA) which used to occupy the Rutherford Appleton Laboratory (RAL) site between 1957 and 1969. The component drawings date back to the late 1960s. Due to its age, complexity and a lack of spares, there is a need for a modern solution. This paper documents the development of a new debunching cavity for the ISIS neutron source.

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THPRI059

Field Emission Study of RF cavity in Static Magnetic Field

cathode, gun, solenoid, electron

3905

T.H. Luo, D. Li
LBNL, Berkeley, California, USA
W. Gai
ANL, Argonne, Illinois, USA
J.H. Shao
TUB, Beijing, People's Republic of China

The RF cavity performance in solenoid magnetic field is crucial for the muon ionization cooling. Previous experiments have shown that the strong external magnetic field can significantly lower the maximum achievable RF voltage in the cavity. The mechanism of this performance degradation has been studied both analytically and experimentally, but so far no conclusive cause has been determined yet. In this paper, we propose an experiment to study the effect of a static B field on the field emission in the RF cavity, which hasn't been investigated before, and which can contribute to the cavity performance degradation in the solenoid field.

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THPRI061

Perpendicular Biased Ferrite Tuned Cavities for the Fermilab Booster

booster, TRIUMF, proton, injection

3911

G.V. Romanov, M.H. Awida, T.N. Khabiboulline, W. Pellico, C.-Y. Tan, I. Terechkine, V.P. Yakovlev, R.M. Zwaska
Fermilab, Batavia, Illinois, USA

The aging Fermilab Booster RF system needs an upgrade to support future experimental program. The important feature of the upgrade is substantial enhancement of the requirements for the accelerating cavities. The new requirements include enlargement of the cavity beam pipe aperture, increase of the cavity voltage and increase in the repetition rate. The modification of the present traditional parallel biased ferrite cavities is rather challenging. An alternative to rebuilding the present Fermilab Booster RF cavities is to design and construct new perpendicular biased RF cavities, which potentially offer a number of advantages. An evaluation and a preliminary design of the perpendicular biased ferrite tuned cavities for the Fermilab Booster upgrade is described in the paper. Also it is desirable for better Booster performance to improve the capture of beam in the Booster during injection and at the start of the ramp. One possible way to do that is to flatten the bucket by introducing second harmonic cavities into the Booster. This paper also looks into the option of using perpendicularly biased ferrite tuners for the second harmonic cavities.

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THPRI062

CW Room Temperature Re-buncher for the PIP-II Linac Front End

linac, proton, beam-transport, experiment

3914

I. Terechkine, M. Chen, I.V. Gonin, S. Kazakov, T.N. Khabiboulline, L. Ristori, G.V. Romanov
Fermilab, Batavia, Illinois, USA

At Fermilab there is a plan for improvements to the Fermilab accelerator complex aimed at providing a beam power capability of at least 1 MW on target. The essential element of the plan (the Proton Improvement Plan II – PIP-II) is a new 800 MeV superconducting linac. The PIP-II linac includes a room temperature front-end and high energy part based on five types of superconducting cavities used to cover the entire velocity range required for beam acceleration. The room temperature front end is composed of an ion source, low energy beam transport line (LEBT), radio frequency quadrupole (RFQ), and a medium energy beam transport line (MEBT). The paper reports RF design of the re-buncher for MEBT along with thermal analysis of the cavity.

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THPRI064

Plasma Chemistry in a High Pressure Gas Filled RF Test Cell for use in a Muon Cooling Channel

ion, electron, plasma, experiment

3917

B.T. Freemire, Y. Torun
IIT, Chicago, Illinois, USA
M. Chung, M.R. Jana, M.A. Leonova, A. Moretti, T.A. Schwarz, A.V. Tollestrup, Y. Torun, K. Yonehara
Fermilab, Batavia, Illinois, USA
R.P. Johnson
Muons, Inc, Illinois, USA

Filling an RF cavity with a high pressure gas prevents breakdown when the cavity is placed in a multi-Tesla external magnetic field. A beam of particles traversing the cavity, be it muons or protons, ionizes the gas, creating an electron-ion plasma which absorbs energy from the cavity. In order to understand the nature of this plasma loading, a variety of gas species, gas pressures, dopants, and cavity electric fields were investigated. Plasma induced energy loss, electron-ion recombination rates, ion-ion recombination rates, and electron attachment times were measured. The results for hydrogen, deuterium, helium, and nitrogen, doped with dry air will be presented.

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THPRI065

Effects of Beam Loading and Higher-order Modes in RF Cavities for Muon Ionization Cooling

beam-loading, plasma, space-charge, higher-order-mode

3921

M. Chung, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
F. Marhauser
Muons, Inc, Illinois, USA

Envisioned muon ionization cooling channel is based on vaccum and/or gas-filled RF cavities of frequencies of 325 and 650 MHz. In particular, to meet the luminosity requirement for a muon collider, the muon beam intensity should be on the order of 10¹² muons per bunch. In this high beam intensity, transient beam loading can significantly reduce the accelerating gradients and deteriorate the beam quality. We estimate this beam loading effect using an equivalent circuit model. For gas-filled cavity case, the beam loading is compared with plasma loading. We also investigate the excitation of higher-order modes and their effects on the performance of the cavity.

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THPRI066

Design of a 1.3 GHz Two-cell Buncher for APEX

HOM, impedance, dipole, vacuum

3924

H.J. Qian, K.M. Baptiste, J.A. Doyle, D. Filippetto, S. Kwiatkowski, C. F. Papadopoulos, D. Patino, F. Sannibale, J.W. Staples, S.P. Virostek, R.P. Wells
LBNL, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
The design of a 1.3 GHz buncher cavity for the APEX project, a MHz repetition rate high-brightness photoinjector, is presented. The buncher cavity operates at 240 kV in CW mode, and it compresses the 750 keV beam from APEX gun through ballistic compression. Compared with a single cell design, a two-cell cavity doubles the shunt impedance to 7.8 MΩ, which greatly relaxes the requirements for both RF amplifier and cavity cooling. Coupler design, multipacting analysis, HOM analysis and thermal analysis will be presented in this paper.

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THPRI070

Tuner System Simulation and Tests for the 201-MHz MICE Cavity

simulation, controls, vacuum, feedback

3927

L. Somaschini
INFN-Pisa, Pisa, Italy
A.J. DeMello, A.R. Lambert, S.P. Virostek
LBNL, Berkeley, California, USA
J.H. Gaynier, R.J. Pasquinelli, D.W. Peterson, R.P. Schultz
Fermilab, Batavia, Illinois, USA
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

Funding: Supported by the US Department of Energy Office of Science through the Muon Accelerator Program.
The frequency of MICE cavities is controlled by pneumatic tuners as their operation is impervious to large magnetic fields. The mechanical and RF transfer functions of the tuner were simulated in ANSYS. The first of these tuning systems was assembled and tested at Fermilab. The mechanical response and the RF tuning transfer function have been measured and compared with simulation results. Finally the failure of different actuators has been simulated and tested to predict the operational limits of the tuner.

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THPRI071

Instrumentation for Characterizing 201-MHz MICE Cavity at Fermilab

vacuum, pick-up, instrumentation, electron

3930

M. Chung, D.L. Bowring, A. Moretti, R.J. Pasquinelli, D.W. Peterson, R.P. Schultz
Fermilab, Batavia, Illinois, USA
P.G. Lane, Y. Torun
Illinois Institute of Technology, Chicago, Illinois, USA
L. Somaschini
INFN-Pisa, Pisa, Italy

A 201-MHz single cavity module is installed in the Mucool Test Area (MTA) of Fermilab to test the performance of the cavity at the design parameters for the International Muon Ionization Cooling Experiment (MICE) particularly in multi-Tesla external magnetic fields. To monitor various aspects of the cavity and to understand detailed physics involved in RF breakdown and multipacting, numerous instrumentation is installed on the cavity module and also in the experimental hall, which includes thermocouples, infrared sensors, electron pickups, fiber light guides, and radiation detectors. In this paper, we will present details of each diagnostic and initial test results.

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THPRI073

Achieving Higher Energies via Passively Driven X-band Structures

impedance, electron, linac, FEL

3933

T. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA

Due to their higher intrinsic shunt impedance X-band accelerating structures significant gradients with relatively modest input powers, and this can lead to more compact particle accelerators. At the Colorado State University Accelerator Laboratory (CSUAL) we would like to adapt this technology to our 1.3 GHz L-band accelerator system using a passively driven 11.7 GHz traveling wave X-band configuration that capitalizes on the high shunt impedances achievable in X-band accelerating structures in order to increase our overall beam energy in a manner that does not require investment in an expensive, custom, high-power X-band klystron system. Here we provide the design details of the X-band structures that will allow us to achieve our goal of reaching the maximum practical net potential across the X-band accelerating structure while driven solely by the beam from the L-band system.

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THPRI078

Experimental Study of Surface RF Magnetic Field Enhancement Caused by Closely Spaced Protrusions

klystron, vacuum, superconductivity, experiment

3949

F.Y. Wang, C. Adolphsen, J.P. Eichner, C.D. Nantista, L. Xiao
SLAC, Menlo Park, California, USA

The RF magnetic field enhancement between two closely spaced protrusions on a metallic surface has been studied theoretically. It is found that a large enhancement occurs when the field is perpendicular to the gap between the protrusions. This mechanism could help explain the melting that has been observed on cavity surfaces subjected to pulsed heating that would nominally be well below the melting temperature of the surface material. To test this possibility, an experiment was carried out in which a pair of copper “pins” was attached to the base plate of an X-band cavity normally used to study pulsed heating. Melting was observed between the pins when the predicted peak temperature was near or exceeded the copper melting temperature.

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THPRI079

RF BREAKDOWN IN A GAS-FILLED TE01 CAVITY

plasma, klystron, electron, simulation

3952

F.Y. Wang, C. Adolphsen, C.D. Nantista
SLAC, Menlo Park, California, USA

An L-band (1.3 GHz) TE01 mode pillbox cavity has been designed to study rf breakdown in gas. Since there are no surface electric fields, effects from the electron interaction with the surface should not be present as in the DC breakdown case. A CCD camera was used to measure the integrated light pattern through holes in the cavity, and an ultrafast diode was used to observed the evolution of the plasma during breakdown. Some preliminary results of the tests are presented in this paper.

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THPRI080

The New Design for Capture Cavity of CEBAF

coupling, 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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THPRI101

Coupler Kick and Cavity Tilt Effects on Emittance Preservation in Linear Accelerators

emittance, wakefield, linac, factory

4013

A.V. Tsakanian, G.A. Amatuni, B. Grigoryan, I.N. Margaryan, V.M. Tsakanov
CANDLE SRI, Yerevan, Armenia

The effects of the coupler kick and the cavity tilts on the beam dynamics in long linear accelerator are studied. The dispersive and wakefield caused beam emittance dilution are evaluated analytically using two particle model of the beam. The numerical simulations for the European XFEL project are presented.

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THPRI111

Higher Order Mode Absorbers for High Current ERL Applications

HOM, linac, cryomodule, damping

4037

R.G. Eichhorn, J.V. Conway, Y. He, Y. Li, T.I. O'Connel, P. Quigley, J. Sears, V.D. Shemelin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Efficient damping of the higher-order modes (HOMs) of the superconducting cavities is essential for any high current linac, especially for the proposed energy recovery linac at Cornell that aims for high beam currents and short bunches. This contribution will present the design and first result on the HOM absorbers built for the Main Linac Cryomodule (MLC).

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THPRI113

Spallation Neutron Source Cryogenic Test Facility Horizontal Test Apparatus Operation

cryogenics, plasma, operation, SRF

4043

B. DeGraff, B.S. Hannah, T.S. Neustadt, J. Saunders
ORNL RAD, Oak Ridge, Tennessee, USA
R. Afanador, M. Doleans, M.P. Howell, S.-H. Kim, C.J. McMahan
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
The Spallation Neutron Source (SNS) has built Superconducting Radio Frequency (SRF) processing and testing facilities to support improvement programs and future upgrades. The Cryogenic Test Facility (CTF) system is capable of delivering liquid helium at 4.5K to different test apparatus in support of SRF testing. This paper describes the final stages of fabrication, commissioning and the initial operation of the Horizontal Test Apparatus (HTA). The HTA allows for cold testing of single jacketed medium-beta or high-beta SRF cavities. Heat loads, capacities, and other performance data collected during operation will be presented. Cavity testing lifecycle for plasma processing research and development will be discussed. System changes to allow for 2K helium operation in the HTA will also be addressed.

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THPRI114

Apparatus and Technique for Measuring Low RF Resistivity of Tube Coatings at Cryogenic Temperatures

vacuum, cryogenics, electron, network

4046

A. Hershcovitch, M. Blaskiewicz, J.M. Brennan, J. Brodowski, W. Fischer, R. Than, J.E. Tuozzolo
BNL, Upton, Long Island, New York, USA
A.X. Custer, A.A. Dingus, M.Y. Erickson, N.Z. Jamshidi, H.J. Poole
PVI, Oxnard, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
An in-situ technique for coating stainless steel vacuum tubes with Cu was developed to mitigate the problems of wall resistivity that leads to unacceptable ohmic heating of superconducting magnets cold bore and electron cloud generation in RHIC that can limit future machine luminosity enhancement. Room temperature RF resistivity of 10 μm Cu coated stainless steel RHIC beam tube has conductivity close to copper tubing. Before coating the RHIC beam pipe with copper, it is imperative to test the Cu coating’s conductivity at cryogenic. A folded quarter wave resonator structure has been designed and built for insertion in a cryogenic system to measure RF resistivity of copper coated RHIC tubing at liquid helium temperatures. The design is based on making the resonator structure out of a superconducting material such that the copper coating is the most lossy material. RHIC tubing samples prepared with different magnetron sputtering deposition modes are to be optimized by iterative processes. Additionally, this device can also be used for the development of better, cheaper SRF cavities and electron guns. The apparatus and its design details will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI114

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FRXCB01

Overview of Worldwide Accelerators and Technologies for ADS

proton, rfq, ECR, target

4069

W.M. Pan
IHEP, Beijing, People's Republic of China

There are many interesting proposals and programs for accelerator driven subcritical facilities for waste transmutation(ADS) in the world, which is to speed up from the basic study to the real facility, and the significant progress in the development of accelerator technologies, in particular, superconducting RF linacs for ADS, but the key technologies in high power proton accelerator are still severe challenges which call for the closer international cooperation. This talk provides a broad overview of worldwide ADS accelerators.

Slides FRXCB01 [10.151 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-FRXCB01

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