IPAC2013 - List of Keywords (coupling)

Paper	Title	Other Keywords	Page
MOPEA071	Operating the Diamond Storage Ring with Reduced Vertical Emittance	feedback, emittance, target, storage-ring	249
	I.P.S. Martin, M.G. Abbott, M. Apollonio, R. Bartolini, D. Hickin Diamond, Oxfordshire, United Kingdom R. Bartolini JAI, Oxford, United Kingdom
	In a synchrotron radiation light source, a reduction in vertical emittance can potentially increase the source brightness, reduce the spot size for microfocus beam lines or increase the vertical transverse coherence of the photon beam. With this aim, the target vertical emittance for the Diamond storage ring has been recently reduced from 27pm.rad to 8pm.rad (0.3% coupling). In this paper we discuss the main impacts of this reduction, along with the steps that have been taken to stabilise the coupling at the new value.

MOPFI053	Upgrades of the SPS, Transfer Line and LHC Injection Protection Devices for the HL-LHC Era	injection, vacuum, kicker, extraction	401
	Ö. Mete, O. Aberle, F. Cerutti, K. Cornelis, B. Goddard, V. Kain, R. Losito, F.L. Maciariello, M. Meddahi, A. Mereghetti, J.A. Uythoven, F.M. Velotti CERN, Geneva, Switzerland E. Gianfelice-Wendt Fermilab, Batavia, USA
	The challenging High Luminosity LHC (HL-LHC) beam requirements will lead in the future to unprecedented beam parameters along the LHC injector chain. In the SPS accelerator these requests translate into about a factor two higher intensity and brightness than the present design performance. In addition to the challenge of producing and accelerating such beams, these parameters affect the resistance of the existing equipment against beam impact. Most of the protection devices in the SPS ring, its transfer lines and the LHC injection areas will be put under operational constraints which are beyond their design specification. The equipment concerned has been reviewed and their resistance to the HL-LHC beams checked. Theoretical and simulation studies have been performed for the SPS beam scraping system, the protection devices and the dump absorbers of the SPS-to-LHC transfer lines, as well as for the LHC injection protection devices. The first results of these studies are reported, together with the future prospects.

MOPME041	Design and Calculation of the Stripline Beam Position Monitor for HLS II Storage Ring	quadrupole, simulation, storage-ring, impedance	562
	F.F. Wu, C. Cheng, W.B. Li, P. Lu, T.J. Ma, B.G. Sun, H. Xu, Y.L. Yang, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by the National Science Foundation of China (10875117, 11005105, 11175173) According to the requirements of HLS II upgraded, in order to acquire the non-intercepting measurement of beam position and quadrupole component, a new stripline beam position monitor (BPM) was designed for storage ring. The BPM parameters were optimized to acquire impedence matching with characteristic impedance of the external transmission lines and the coupling coefficients between the electrodes were calculated. According to the difference/sum and log-ratio methods, the horizontal and vertical sensitivities, mapping figures and fitting polynomials wered acquired. The results showed that sensitivities using log-ratio method were bigger than those using difference/sum method. The sum signal was also simulated when beam displacement varied from (0 mm, 0 mm) to (5 mm, 5 mm), the result showed that the variation of normalized sum signal was no more than ±6%. The gaussian weighted method of a two-dimensional grid structure was used to simulate the gaussian bunch and simulate the beam transverse quadrupole component changing with position (x, y), the result showed that the beam transverse quadrupole component changed linearly with position combination (x2-y2).

MOPME043	Calibration of Beam Position Monitors in the Injector of HLS II	quadrupole, brilliance, linac, emittance	568
	J.Y. Zou, J. Fang, W.B. Li, P. Lu, T.J. Ma, B.G. Sun, Y.L. Yang, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by the National Science Foundation of China (11175173, 11105141) A beam position monitor(BPM) system is being installed to improve the beam position measurement of the injector at the upgrade project of Hefei Light Source (HLS II). The new BPM system is consists of 19 stripline BPMs and 19 Libera Brilliance Single Pass modules. Before installation, the response of the BPMs must be mapped to improve the accuracy of measurement. The theoretical equations of both position and quadrupole component of the BPM are calculated first, using both formula and matlab simulation. A laboratory calibration system is built. The inconsistency of Libera Brilliance Single Pass channels is measured to improve the accuracy of calibration. The calibrating results show the position sensitivity is less than 5% difference compare to the theoretical value, while the quadrupole component sensitivity is less than 10% difference.

MOPME046	Preliminary Experimental Results of Axial B-dot Measuring Beam Tilt	high-voltage, simulation, dipole, impedance	577
	X. He, Q. Li, C. Ma, J. Pang, L. Zhao CAEP/IFP, Mainyang, Sichuan, People's Republic of China
	Funding: This work is under the support of NSFC project No. 11175166 Beam monitors sensitive to the beam's azimuthal B-dot field (sometimes referred as B-dots) are widly used to measure the displacement of beam centroid, as the beam generates a dipole term of the azimuthal magnetic field. The authors have pointd out that the similar B-dots sensitive to axial magnetic field can be used to measure the beam tilt directly in earlier work. A monitor which consists of four azimuthal B-dots and four axial B-dos is designed and fabricated. The monitor was tested on a coaxial calibration stand, which has a character resistance of 50 Ohm. Two position tuners are installed on the calibration stand, to adjust the position and the tilt of the inner conductor. Experiments show that the axial B-dot monitor can be successfully used to measure the tilt of the inner conductor directly.

MOPME047	Simulation of a Beam Angel Monitor using the Axial B-dot Field	simulation, monitoring, induction, dipole	580
	J. Pang, X. He, Q. Li, C. Ma CAEP/IFP, Mainyang, Sichuan, People's Republic of China
	Funding: The National Natural Science Foundation of China A beam angel monitor using the axial B-dot field was presented recently while the one using azimuthal B-dot field had been widely employed to measure the beam positions for more than ten years. Basing on the principle of the proportionality between the deflection angel and the difference of axial B field with corresponding positions, the axial B-dot monitor has a potential use for beam deflection angle measurement directly. A test stand was built to test and improve the axial B-dot monitor, which is fabricated as a PCB structure. Meanwhile, simulations using the CST MWS code have been performed, demonstrating a good agreement to the test results and giving some advice to suppress the disturbance of position deviation of the beam.

MOPME051	Development of Cavity Beam Position Monitor System	cavity, FEL, simulation, electron	586
	B.P. Wang, Y.B. Leng, Y.B. Yan, L.Y. Yu, R.X. Yuan, W.M. Zhou SINAP, Shanghai, People's Republic of China
	Shanghai soft X-ray free electron laser (SXFEL) facility requires beam position resolution better than 1 μm in the undulator sections. Cavity BPM system, feasible in obtaining sub micron position resolution, has been developed to achieve the goal. Two cavity prototypes with high Q and low Q were designed and fabricated. The relevant dedicated electronic, which could cover the two types of cavity BPMs, also have been developed. Fast fourier transform (FFT) and digital down converted based algorithms were implemented. The beam test of the whole system has been scheduled on the Shanghai deep ultraviolet (SDUV) FEL facility. The cavity design, electronic architecture, achieved performance during beam test will be presented.

MOPME076	Determination of Octupole and Sextupole Polarities in the LHC	octupole, sextupole, injection, lattice	655
	M.J. McAteer, Y.I. Levinsen, E.H. Maclean, T. Persson, P.K. Skowroński, R.J. Steinhagen, R. Tomás CERN, Geneva, Switzerland
	We report the results of measurements to verify the polarity of the LHC’s lattice focusing and defocusing octupoles (MOF and MOD), spool piece octupole correctors (MCO), arc skew sextupole correctors (MSS), and interaction region sextupoles (MCSX and MCSSX). Octupole polarities were determined by measuring the change to second order chromaticity when a magnet family was trimmed. The MSS skew sextupole corrector polarities were checked by measuring the change to chromatic coupling when a magnet family was trimmed. The polarities of the MCSSX skew sextupoles in IR 1 and the MCSX normal sextupoles in IR 5 were checked by measuring the tune shift due to a magnet trim. Comparison of measurements with model predictions indicates that the polarities of the octupoles and the IR sextupoles are correct, and the polarities of the MSS skew sextupole correctors are reversed.

MOPWA023	A Low Jitter Pulse Generator Based on Two-stage Storage Module	pulsed-power, simulation, controls, high-voltage	711
	J.N. Li, W.Q. Chen, F. Guo, W. Jia NINT, Xi'an, People's Republic of China
	A scheme for a low jitter pulse generator based on two-stage storage module is described. The thyristor is used for the first stage of the generator, the UV-illumination gas switch is used for the second stage of the generator. Between them, the pulsed transformer is used for connecting. A capacitance-resistance coupling structure was designed to produce UV light which triggered the switch to decrease the breakdown jitter. The test result shows, the risetime of the current is 0.73μs, the peak value of the current is 1.8kA on 1.1Ω load. The delay of the generator is 35.1μs, and the jitter of the generator attaches to 0.22μs.

MOPWA033	Modelling of Parasitic Inductances of a High Precision Inductive Adder for CLIC	impedance, kicker, damping, emittance	738
	J. Holma, M.J. Barnes CERN, Geneva, Switzerland S.J. Ovaska Aalto University, School of Science and Technology, Aalto, Finland
	The CLIC study is exploring the scheme for an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The CLIC pre-damping rings and damping rings will produce, through synchrotron radiation, ultra-low emittance beam with high bunch charge. To avoid beam emittance increase, the damping ring kicker systems must provide extremely flat, high-voltage, pulses. The specifications for the extraction kickers of the DRs are particularly demanding: the flat-top of the pulses must be ±12.5 kV with a combined ripple and droop of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising approach to meeting the specifications. However, the output impedance of the inductive adder needs to be well matched to the system impedance. The primary leakage inductance, which cannot be computed accurately analytically, has a significant effect upon the output impedance of the inductive adder. This paper presents predictions, obtained by modelling the 3D geometry of the adder structure and printed circuit boards using the FastHenry code, for primary leakage inductance.

MOPWA070	Beam Position Monitor within the Cornell Energy Recovery Linac Cavity Assembly	HOM, pick-up, RF-structure, cavity	840
	M.G. Billing, M. Liepe, V.D. Shemelin, N.R.A. Valles CLASSE, Ithaca, New York, USA
	In an energy recovery Linac (ERL) the low energy beam is very sensitive to deflections due to the RF fields as it passes through the accelerator cavities. Therefore, to avoid the possible effects of beam breakup, it will be important to determine the optimum transverse position for the beam within the first several sets of cavity cells in the cryostat assembly and to maintain this position over long periods. As a result a beam position monitor (BPM) has been designed to be located between the higher-order modes (HOM) loads and the seven-cell RF structures. This BPM’s design reduces the coupling of RF power from the fundamental mode and HOMs into the BPM, while maintaining acceptable position sensitivity and resolution. We analyzed the coupling of the probe to the HOMs of realistically shaped cavities by generating geometries for hundreds of cavities having small shape variations from the nominal dimensions consistent with present machining tolerances, and solved for their monopole and dipole spectra. Our results show that the peak, dissipated power within BPM cables, which pass through the cryostat, is well within the permissible levels.

MOPWO023	Upgrade and Systematic Measurement Campaign of the ATF2 Multi-OTR System	target, emittance, wakefield, extraction	933
	A. Faus-Golfe, J. Alabau-Gonzalvo, C. Blanch Gutierrez, J. Resta-López IFIC, Valencia, Spain J. Cruz, E. Marín, D.J. McCormick, G.R. White, M. Woodley SLAC, Menlo Park, California, USA
	A multi-Optical Transition Radiation (mOTR) system made of four stations is being used routinely since September 2011 for transverse beam size measurement and emittance reconstruction in the extraction line of ATF2, providing diagnostic support during the ATF2 tuning operation. Furthermore it is also an excellent tool for fast transverse coupling correction. Due to the compactness of the current design the system has an influence in the increase of the transverse emittance due to wakefield effects when a simultaneous measurement is made. To avoid this effect a new target holder and a new optics has been designed and implemented. In this paper we describe the present status of the ATF2 mOTR system, showing recent performance results, and hardware design improvements.

MOPWO061	Numerical Approaches for Simulation of Stochastic Cooling in 2D Phase Space	emittance, simulation, electromagnetic-fields, storage-ring	1028
	M. Dolinska NASU/INR, Kiev, Ukraine C. Dimopoulou, A. Dolinskyy, F. Nolden GSI, Darmstadt, Germany
	A consolidated fluid-dynamics algorithm for the analysis of beam dynamics under the influence of the electromagnetic field is presented. Aiming at simulating stochastic cooling of particle beams in 2D space, two numerical algorithms solving the 2D Fokker-Planck Equation are described. As an alternative approach, a numerical method based on the macro-particle tracking turn in turn in the ring (i.e. in the time domain) is introduced. Some results of the simulation of the stochastic cooling in the Collector Ring by both methods are discussed.

TUODB103	Recent Results from CesrTA Intrabeam Scattering Investigations	emittance, simulation, damping, scattering	1126
	M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, D. Sagan, J.P. Shanks, S. Wang CLASSE, Ithaca, New York, USA
	Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505. Manifestation of intrabeam scattering (IBS) in an electron/positron storage ring depends on the radiation damping time in two ways. First, the beam size is the equilibrium of the IBS growth rate in each of the three degrees of freedom and corresponding damping rates. Second, scattering events that occur less frequently than order once per damping time contribute to non-Gaussian tails that are invisible to our beam size monitors. The tail cut procedure excludes these relatively rare events in the calculation of equilibrium beam size. In machines with short damping times, the tail cut significantly reduces the effective IBS growth rate. At CesrTA, we measure the dependence of beam size on bunch charge in IBS-dominated beams. We vary the vertical emittance using a closed optics bump that increases the vertical dispersion and transverse coupling in the wiggler regions. Measurements are taken at both 2.1 and 2.3 GeV. Here we report the results of these experiments and compare those results to theory.
	Slides TUODB103 [1.221 MB]

TUPEA012	Rebunching Ultracold Neutrons by Magnetic Deceleration for the neutron EDM experiment at J-PARC	neutron, resonance, power-supply, focusing	1187
	S. Imajo Kyoto University, Kyoto, Japan Y. Arimoto KEK, Ibaraki, Japan P.W. Geltenbort ILL, Grenoble, France Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan M. Kitaguchi Kyoto University, Research Reactor Institute, Osaka, Japan Y. Seki RIKEN Nishina Center, Wako, Japan H.M. Shimizu Nagoya University, Nagoya, Japan T. Yoshioka Kyushu University, Fukuoka, Japan
	Ultra cold neutrons (UCN) - neutrons with energies less than 300 neV - can be accelerated or decelerated by means of static magnetic and RF fields. Neutron have a magnetic dipole moment, and hence their kinetic energies vary depending on their spin in magnetic fields. Their kinetic energies are restored when they get out from the magnetic field area if their spin did not flip. A spin flip can be triggered by applying an RF field whose frequency coincides with the spin precession frequency of a neutron in this magnetic field. This allows to tune the kinetic energy of neutrons. This method can be used to rebunch a pulsed beam of neutrons to a storage bottle that can store UCN. By open and close the storage bottle synchronously with the rebuncher, high UCN densities can be achieved for precision measurements of neutron properties such as the Electric Dipole Moment. The method and experimental setup are described in detail and the results of a recent first test experiments are presented.

TUPEA079	Experimental Search For Acceleration in the Micro-accelerator Platform	laser, electron, acceleration, vacuum	1307
	J.C. McNeur, K.S. Hazra, B. Matthews, E.B. Sozer, G. Travish UCLA, Los Angeles, USA R.J. England, B. Montazeri, K. Soong, Z. Wu SLAC, Menlo Park, California, USA E.A. Peralta Stanford University, Stanford, California, USA R.B. Yoder Goucher College, Baltimore, USA
	The results of recent experimental efforts to observe acceleration in the Micro-Accelerator Platform (MAP) are detailed. The MAP is a slab-symmetric dielectric laser accelerator that when side illuminated by an optical laser, accelerates electrons via a standing wave resonance. This structure has been placed in the beamline at the NLCTA experimental hall at SLAC. A 60 MeV electron beam traverses the MAP when it is illuminated by a laser and, using a camera placed around a spectrometer bend magnet, signs of acceleration in the energy spectrum of the beam are searched for. The details of this search, as well as simulations that motivate the search, are elaborated on below.

TUPFI039	Optics Performance of the LHC During the 2012 Run	optics, sextupole, quadrupole, octupole	1433
	P. Skowroński, T. Bach, M. Giovannozzi, A. Langner, Y.I. Levinsen, E.H. Maclean, T. Persson, S. Redaelli, T. Risselada, M. Solfaroli Camillocci, R. Tomás, G. Vanbavinckhove CERN, Geneva, Switzerland M.J. McAteer The University of Texas at Austin, Austin, USA R. Miyamoto ESS, Lund, Sweden T. Persson Chalmers University of Technology, Chalmers Tekniska Högskola, Gothenburg, Sweden
	During 2012 the LHC was operating at 4TeV with beta star at ATLAS and CMS interaction points of 0.6m. During dedicated machine studies the nominal LHC optics was also setup with beta star of 0.4m. A huge effort was put into the optics commissioning leading to a record low peak beta-beating of around 7%. We describe the correction procedures and discuss the measurement results.

TUPFI065	Muon Ionization Cooling Experiment Step VI	cavity, emittance, vacuum, status	1499
	D. Rajaram Illinois Institute of Technology, Chicago, Illinois, USA P. Snopok IIT, Chicago, Illinois, USA
	The Muon Ionization Cooling Experiment (MICE) is a demonstration experiment to prove the viability of cooling a beam of muons for use in a Neutrino Factory and Muon Collider. The ultimate Step VI configuration of the MICE cooling channel, a section of the one proposed in the Neutrino Factory Study II, will demonstrate a 10% reduction in transverse beam emittance measured at the level of 1%. This requires measuring emittance to 0.1%. This measurement will be made using all beam line elements present in the MICE Step IV configuration with the addition of two low-Z absorber modules and two RF-Coupling Coil (RFCC) modules. The RFCC modules each contain four normal-conducting low frequency (201 MHz) RF cavities with a guiding magnetic field provided by a large diameter coupling coil. Each of these cavities will require approximately 1 MW of RF power in a 1 ms pulse at a rate of 1 Hz. The experiment can explore a variety of combinations of momentum, beta function, magnetic field flip or non-flip configurations that will prove precious in the design of future cooling channels. The current status and progress toward Step VI are discussed.

TUPME012	Space Charge Simulation based on a Measured Optics in J-PARC MR	optics, space-charge, resonance, sextupole	1589
	K. Ohmi, S. Igarashi, Y. Sato, J. Takano KEK, Ibaraki, Japan S. Hatakeyama JAEA/J-PARC, Tokai-mura, Japan
	Linear optics parameters, beta, alpha, phase, x-y coupling and dispersion are measured by phase space monitor and/or other tools. Nonlinear effects due to the space charge and magnets are dominantly determined by linear optics. For example, the beam distribution is mainly determined by linear optics, and error of beta function at a sextuple magnet is larger than error of magnet strength generally. This means space charge simulation based on the measured optics takes into account of the major part of errors. We discuss how beam loss degrade and which resonances are induced by the errors in the simulations.

TUPME030	Emittance Reconstruction from Measured Beam Sizes	emittance, simulation, optics, FEL	1640
	J. Giner Navarro, A. Faus-Golfe, J. Fuentes, J. Navarro, J. Resta IFIC, Valencia, Spain
	In this paper we analyze the projected emittance (2D) and the intrinsic emittance (4D) reconstruction method by using the beam size measurements at different locations. We have studied analytically the conditions of solvability of the systems of equations involved in this process and we have obtained some rules about the locations of the measurement stations to avoid unphysical results. Presently, simulations are being made to test the robustness of the algorithm in realistic scenarios with high coupling and measurement errors. The special case of a multi-OTR system in ATF2 is being studied in much detail. The results of these studies will be very useful to better determine the location of the emittance measurement stations in the diagnostic sections of Future Linear Colliders.

TUPME033	Evaluation of the Beam Coupling Impedance of New beam Screen Designs for the LHC Injection Kicker Magnets	impedance, kicker, injection, resonance	1649
	H.A. Day UMAN, Manchester, United Kingdom M.J. Barnes, F. Caspers, E. Métral, B. Salvant CERN, Geneva, Switzerland R.M. Jones Cockcroft Institute, Warrington, Cheshire, United Kingdom
	The LHC injection kicker magnets (MKIs) have experienced a significant degree of beam induced heating since the beginning of the 2011 due to the increasing intensity stored in the LHC, for long periods of time, and the relatively large broadband impedance of the installed kicker magnets. In this paper we show the sources of impedance in the MKIs, especially the effect that the beam screen dimensions have on the impedance. We show how these alter the power loss, and present an improved beam screen design that improves shielding on the magnet, whilst further improving electrical breakdown.

TUPME052	Sub-harmonic Buncher Design for the CLIC Drive Beam Injector	beam-loading, electron, linear-collider, collider	1685
	H. Shaker, S. Döbert, R. Leuxe, S. Sanaye Hajari CERN, Geneva, Switzerland L. Dassa Università di Brescia, Brescia, Italy S. Sanaye Hajari, H. Shaker IPM, Tehran, Iran
	The CLIC (Compact LInear Collider) is based on two beam concept where a high current drive beam provides the energy needed for acceleration of the main beam. The CLIC drive beam accelerator starts with a high current injector using a sophisticated sub-harmonic bunching system. This paper will focus on the design of the Sub Harmonic Bunchers (SHBs) the first RF components of the injector. A backward traveling wave structure has been optimized for this task. It will be shown also how to avoid asymmetrical fields inside the coupler cells and how to compensate beam loading by changing the phase velocity in comparison to the beam velocity.

TUPME065	Experimental Study of Horizontal-Longitudinal Coupling at CesrTA	lattice, cavity, simulation, scattering	1715
	M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, S. Wang CLASSE, Ithaca, New York, USA
	Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505. In storage rings, the presence of horizontal dispersion in the RF cavities introduces x-z coupling. The result is that the beam is skewed in the horizontal-longitudinal plane. The skew angle is proportional to the V15 term of the 6X6 coupling matrix which is proportional to the RF cavity voltage and the horizontal dispersion in the cavity. Here we report experiments at CesrTA where x-z coupling was explored using three distinct lattice configurations with different V15 coupling terms. We explore x-z coupling for each of these lattices by measuring the horizontal projection of the beam with a beam size monitor, as the RF voltage is varied. The first lattice has about 1 m dispersion in the RF cavities, resulting in a V15 term at the beam size monitor source point corresponding to 16 mrad x-z tilt. In the second, the V15 generated in one pair of cavities is compensated at the second pair by adjusting the horizontal betatron phase advance between the cavity pairs. In the third, the optics are adjusted so that the RF cavity region is dispersion-free, eliminating the coupling entirely. Additionally, intra-beam scattering is evident in our measurements of beam size vs. RF voltage.

TUPWA003	Beam Based Magnet Alignment for Emittance Coupling Minimization	sextupole, quadrupole, emittance, storage-ring	1724
	R.T. Dowd, G. LeBlanc, Y.E. Tan ASCo, Clayton, Victoria, Australia K.P. Wootton The University of Melbourne, Melbourne, Australia
	Magnet misalignments give rise to field terms which can cause coupling between the horizontal and vertical beam motion and therefore emittance coupling. A series of beam based measurements have been developed at the Australian Synchrotron to accurately quantify quadrupole and sextupole alignments errors which cause coupling and where possible, correct them. Results showing an reduction in emittance coupling due to realignments of magnets based on these measurements will be presented. Limitations and general applicability of this method will also be discussed.

TUPWA014	The Status of Coupling Impedance Measurement for the CSNS/RCS Extraction Kicker Prototype*	impedance, kicker, simulation, extraction	1754
	L. Huang, Y. Li, R.H. Liu, Y.D. Liu, S. Wang, O. Xiao IHEP, Beijing, People's Republic of China
	Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) is a high intensity proton accelerator, with average beam power of 100kW. In order to high intensity beam operation, the beam coupling impedance of the extracted kickers must be controlled. Longitudinal and transverse impedance of extracted kicker prototype with power supply had been roughly measured by coaxial-wire and dual-wire methods respectively. At the same time, impedance of window has been analyzed theoretically and simulated based on CST PARTICLE STUDIO.

TUPWA030	Impedances Calculations of Bellows in HLS II Storage Ring	impedance, wakefield, storage-ring, shielding	1784
	Q. Zhang, W. Li, L. Wang USTC/NSRL, Hefei, Anhui, People's Republic of China
	The upgrade project of Hefei Lighe Source storage ring is carrying on.In this project,a new Bellows, in which shielding is provided by sprung fingers which can slide along the beam screen,is installed at the accelerator interaction area In order to reduce this impedance to an acceptable value. The contributions of Bellows to short range wakefields and broadband impedance were calculated numerically by Mafia code .

TUPWA050	Effect of Transverse Coupling on Asymmetric Cooling in Compton Rings	emittance, laser, electron, betatron	1823
	E.V. Bulyak NSC/KIPT, Kharkov, Ukraine J. Urakawa KEK, Ibaraki, Japan F. Zimmermann CERN, Geneva, Switzerland
	Fast cooling of bunches circulating in a Compton ring is achieved by placing the collision point between electron bunches and laser pulses in a dispersive section and by, in addition, introducing a transverse offset between the laser pulse and the electron-beam closed orbit. Growth of the emittance in the dispersive transversal direction due to the additional excitation of betatron oscillations limits this type of cooling. Here we present the results of further studies on the fast cooling process, looking at the effect of the coupling of the transverse (betatron) oscillations. We first show theoretically that the transverse betatron coupling shortens the cooling time and hence reduces the steady-state energy spread of the electron beam, as well as the quantum losses. The theoretical estimates are then validated by simulations. Finally, a proof-of-principle experiment at the KEK ATF Damping Ring is proposed.

TUPWO001	A New 5BA Low Emittance Lattice for Sirius	emittance, lattice, dipole, sextupole	1874
	L. Liu, N. Milas, A.H.C. Mukai, X.R. Resende, A.R.D. Rodrigues, F. H. de Sá LNLS, Campinas, Brazil
	Sirius is a third-generation low emittance synchrotron light source under construction at LNLS, the Brazilian Synchrotron Light Laboratory. A new 5BA lattice was designed in replacement for the previous TBA lattice with the aim to reduce the emittance to sub-nm.rad values. The new design has a circumference of 518 m with 20 achromatic straight sections and a natural emittance of 0.28 nm.rad at 3 GeV for the bare lattice (without IDs). The dipoles combine low 0.58 T field magnets for the main beam deflection with a 2 T short superbend magnet sandwiched in the center dipole. This creates a longitudinal dipole gradient that is used both to lower the emittance and to provide hard X-ray dipole sources.

TUPWO009	Decoupling Capabilities Study of the Emittance Transfer Section	emittance, solenoid, quadrupole, stripper	1895
	C. Xiao, O.K. Kester IAP, Frankfurt am Main, Germany L. Groening, O.K. Kester, M.T. Maier GSI, Darmstadt, Germany
	Flat beams are those which feature unequal emittances in the horizontal and vertical phase space. The present paper is on the planning of the experimental proof of principle. Detailed simulations of the experiment, initially based on linear matrix transformations, are performed. The remarkable flexibility of the set-up w.r.t. to decoupling is addressed, as it can provide an one-knob tool to set the horizontal and vertical emittance partitioning. It was found that the decoupling capability of the set-up is remarkably flexible and the impact and discussion of this finding is treated in a dedicated section

TUPWO011	Invariant Criterion for the Design of Multiple Beam Profile Emittance and Twiss Parameters Measurement Sections	emittance, betatron, simulation, optics	1901
	V. Balandin, W. Decking, N. Golubeva DESY, Hamburg, Germany
	By studying errors in the reconstructed beam parameters as functions of the errors in the beam size measurements, we introduce an optimality criteria which can be used for the design and comparison of multiple beam profile emittance and Twiss parameters measurement sections and which is independent from the position of the reconstruction point.

TUPWO012	Relations Between Projected Emittances and Eigenemittances	emittance, beam-transport, electron, quadrupole	1904
	V. Balandin, W. Decking, N. Golubeva DESY, Hamburg, Germany
	We give necessary and sufficient conditions which two sets of positive real numbers must satisfy in order to be realizable as eigenemittances and projected emittances of a beam matrix. The information provided by these conditions sets limits on what one can to achieve when designing a beam line to perform advanced emittance manipulations (for example, round-to-flat beam transformations).

TUPWO017	Simulation on the Breaking of αx Multiknob Orthogonality in the Presence of Gradient and Coupling Errors and Experimental Investigation	simulation, quadrupole, sextupole, linear-collider	1919
	S. Bai, J. Gao IHEP, Beijing, People's Republic of China P. Bambade LAL, Orsay, France G.R. White SLAC, Menlo Park, California, USA
	The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. In beam tuning towards the goal beam size, the presence of a tilt of the IP Shintake monitor fringe pattern with respect to the x-y coordinate system of the beam can break the orthogonality in the main σ34 and σ32 waist corrections required to reduce the vertical beam size at IP. Concerning the method of doing αx scan and measuring the vertical beam size to diagnose the IPBSM fringe tilt or residual σ13, one thing should be studied is to check what could break the orthogonality of the αx knob other than σ13 and the IPBSM fringe tilt. In this paper, we report on the simulation study that check for the breaking of orthogonality of the αx knob in the presence of gradient and coupling errors; to what extent this breaking of orthogonality can go; and also calculate the IPBSM fringe tilt angle from experiment results.

TUPWO047	Preliminary Results of Linear Optics From Orbit Response in the CERN PSB	quadrupole, dipole, optics, booster	1973
	M.J. McAteer, C. Carli, B. Mikulec, R. Tomás CERN, Geneva, Switzerland M. Aiba PSI, Villigen PSI, Switzerland
	Funding: This research project is supported by a Marie Curie Early Initial Training Network Fellowship of the European Community's Seventh Framework Programme under contract number (PITN-GA-2011-289485-OPAC) Future operations for the CERN accelerator complex will require the PS Booster to deliver higher intensity beam without increasing emittances, and having an accurate knowledge of the machine’s lattice imperfections will be necessary. We present preliminary results of the analysis of orbit response measurements in the PS Booster to determine the linear optics and to identify field errors in each of the machine’s four rings.

TUPWO048	Understanding the Tune, Coupling, and Chromaticity Dependence of the LHC on Landau Octupole Powering	closed-orbit, octupole, alignment, simulation	1976
	E.H. Maclean, M. Giovannozzi, W. Herr, Y.I. Levinsen, G. Papotti, T. Persson, P.K. Skowroński, R. Tomás, J. Wenninger CERN, Geneva, Switzerland
	During the 2012 LHC run there were several observations of unexpectedly large shifts to the tune, chromaticity, and coupling which were correlated with changes in the powering of Landau octupoles (MO). Understanding the chromaticity dependence is of particular importance given it's influence on instabilities. This paper summarizes the observations and our attempts to-date to understand the relationship between Q, Q', c- and the MO powering.

TUPWO049	Automatic Correction of Betatron Coupling in the LHC using Injection Oscillations	injection, controls, quadrupole, betatron	1979
	T. Persson, T. Bach, D. Jacquet, V. Kain, Y.I. Levinsen, E.H. Maclean, M.J. McAteer, P.K. Skowroński, R. Tomás, G. Vanbavinckhove CERN, Geneva, Switzerland R. Miyamoto ESS, Lund, Sweden
	The control of the betatron coupling at injection and during the energy ramp is critical for the safe operation of the tune feedback and for the dynamic aperture. In the LHC every fill is preceded by the injection of a pilot bunch with low intensity. Using the injection oscillations from the pilot bunch we are able to measure the coupling at each individual BPM. The measurement is used to calculate a global coupling correction. The correction is based on the use of two orthogonal knobs which correct the real and imaginary part of the difference resonance term f1001, respectively. This method to correct the betatron coupling has been proven successful during the normal operation of the LHC. This paper presents the method used to calculate the corrections and its performance.

TUPWO064	Online Optimization Algorithms for Accelerators and Experimental Results	injection, optics, quadrupole, simulation	2012
	X. Huang, W.J. Corbett, J.A. Safranek, J. Wu SLAC, Menlo Park, California, USA
	Online optimization of accelerators is becoming increasingly more important as accelerator systems become more and more complex. Online accelerator optimization is generally a multi-variant nonlinear problem with considerable noise. Efficiency and robustness are critical for online applications. Therefore optimization algorithms require special considerations. In this study we evaluate the viability of several online optimization algorithms for both ring and linac machines. Numerical simulations and experimental tests are presented to investigate performance of the algorithms.

WEPWO014	Rf Field-Attenuation Formulae for the Multilayer Coating Model	cavity, vacuum, electromagnetic-fields	2343
	T. Kubo, T. Saeki KEK, Ibaraki, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan
	Formulae that describe the RF electromagnetic field attenuation in the multilayer coating model with a single superconductor layer and a single insulator layer deposited on a bulk superconductor are derived with a rigorous calculation based on the Maxwell equations and the London equation.

WEPWO042	Dubna-Minsk SRF Technology Development Status Report	cavity, cryogenics, niobium, electron	2393
	N.S. Azaryan, Ju. Boudagov, D.L. Demin, V.V. Glagolev, G. Shirkov, G.V. Trubnikov JINR, Dubna, Moscow Region, Russia M.A. Baturitsky, N.M. Shumeiko NC PHEP BSU, Minsk, Belarus S.E. Demyanov, E.Yu. Kaniukov Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus, Minsk, Belarus A. Ermakov, W. Singer, X. Singer DESY, Hamburg, Germany V.A. Karpovich, N.V. Liubetsky BSU, Minsk, Belarus S.V. Kolosov, A.A. Kurayev, A.O. Rak, A.K. Sinitsyn Belarus State University of Informatics and Radioelectronics (BSUIR), Minsk, Belarus S.I. Maximov, V.N. Rodionova Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk, Belarus A. Parshuto, V.S. Petrakovsky, I.L. Pobol, A.I. Pokrovsky, S.V. Yurevich, A.Yu. Zhuravsky Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus
	In 2011 Dubna-Minsk collaboration started an activity on the development and manufacture the series of 1.3 GHz superconducting Nb cavities in the enterprises in Belarus. The current status of this work is presented in this report. Main EM characteristics of the cavity were calculated and the shop drawings for cavity fabrication were developed. Two test-benches were assembled for RF-tests of the cavities at room temperature and at liquid helium temperature. The measured SWR was about 1.01 due to special matching device developed for that. This measurement technique was applied to the single-cell cavity from FNAL at power level nearby 10 mW. Measured resonant frequency was about 1.27 GHz, while the measured Q-factor was 2.8·10⁴ at room temperature and more than 10⁸ at liquid helium temperature. To evaluate mechanical properties of sheet Nb and of model materials (Cu and Al), a number of tests were made. Series of half-cells were fabricated of Al to test the technique of hydraulic deep-drawing that will be used in production of Nb cavities. The modes for electron-beam welding of sheet Nb were explored and the first welding seams were tested. The method of chemical treatment of cavities was also elaborated.
	Poster WEPWO042 [0.897 MB]

WEPWO046	First Test Results of the 4-rod Crab Cavity	cavity, vacuum, niobium, pick-up	2405
	R. Calaga, L.S. Alberty Vieira, S. Calatroni, O. Capatina, E. Ciapala, L.M.A. Ferreira, E. Jensen, P. Maesen, A. Mongelluzzo, T. Renaglia, M. Therasse CERN, Geneva, Switzerland P.K. Ambattu, D. Doherty, B.D.S. Hall, C. Lingwood Cockcroft Institute, Lancaster University, Lancaster, United Kingdom G. Burt Lancaster University, Lancaster, United Kingdom
	Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The first prototype crab cavity with the 4-rod geometry has undergone surface treatment and cold testing. Due to the complex geometry and unique fabrication procedure, RF validation of the field at beyond the nominal operating voltage at a sufficiently high Q0 is an important pre-requiste. Preliminary results of the first cold tests are presented along with cavity performance at different stages of the cavity processing is described.

WEPWO072	HOM Damping Coupler Design for the 400-MHz RF Dipole Compact Crab Cavity for the LHC HiLumi Upgrade	HOM, cavity, dipole, damping	2468
	Z. Li, L. Ge SLAC, Menlo Park, California, USA S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA
	Funding: Work partially supported by the US DOE through the US LHC Accelerator Research Program (LARP), and by US DOE under contract number DE-AC02-76SF00515. Crab cavities are adapted as the baseline design for the LHC HiLumi upgrade to achieve head-on beam-beam collisions for further improvement in luminosity. A 400-MHz compact RF dipole crab cavity design was developed by a joint effort between Old Dominion University and SLAC under the support of US LARP program. This design has shown very favorable RF parameters and can fit into the available beamline spacing for either vertical and horizontal crabbing schemes. A niobium prototype cavity based on such a design has been manufactured for vertical test. In addition, there are stringent wakefield requirements that needed to be met for such a cavity in order to preserve the quality of the circulating beams. In this paper, we will discuss different damping schemes for such a compact design and present the HOM coupler designs to meet the damping requirements.

WEPWO073	RF Design Optimization for New Injector Cryounit at CEBAF	cavity, cryomodule, SRF, injection	2471
	H. Wang, G. Cheng, F.E. Hannon, A.S. Hofler, R. Kazimi, J.P. Preble, R.A. Rimmer JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A new injector superconducting RF (SRF) cryounit with one new 2-cell, β=0.6 cavity plus one refurbished 7-cell, β=0.97, C100 style cavity has been re-designed and optimized for the engineering compatibility of existing module for CEBAF operation. The optimization of 2-cell cavity shape for longitudinal beam dynamic of acceleration from 200keV to 533keV and the minimization of transverse kick due to the waveguide couplers to less than 1 mrad have been considered. Operating at 1497MHz, two cavities has been designed into a same footprint of CEBAF original quarter cryomodule to deliver an injection beam energy of 5MeV in less than 0.27o rms bench length and a maximum energy spread of 5keV.

WEPWO084	Improvement of the Q-factor Measurement in RF Cavities	cavity, dipole, pick-up, HOM	2489
	W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi 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. The Q values of Higher-order-modes (HOMs) in RF cavities are measured at room temperature with the 3 dB bandwidth reading by a network analyzer. The resonant curve distortion is created by the resonance splitting due to the ellipticity caused by manufacture tolerance and RF ports. Therefore, the measured Q values are usually lower than the simulated or theoretical Q values. In some cases, even only one mode’s Q can be measured with the 3 dB method. There may be two reasons for this happening. One is that only one mode was excited and the neighbor splitmode was close to 90° polarized; the other reason is that the resonant curve of one mode was distorted by the other mode too much to measure the 3dB range. In this paper, we resolve this issue by looking into the RF measurement setup, including cavity, input coupler and pick-up coupler, from the equivalent circuit and wave point of view. Based on the BNL3 copper prototype cavity, we compared these results from measurement and simulation.

WEPEA064	SixTrack-Fluka Active Coupling for the Upgrade of the SPS Scrapers	simulation, injection, luminosity, synchrotron	2657
	A. Mereghetti, F. Cerutti, R. De Maria, B. Goddard, V. Kain, M. Meddahi, O. Mete, Y. Papaphilippou, D. Pastor Sinuela, V. Vlachoudis CERN, Geneva, Switzerland R. Appleby UMAN, Manchester, United Kingdom
	The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Essential for the clean injection into the LHC, the SPS scrapers are one of the important systems under revision. In order to take into account of the effect of betatron and longitudinal beam dynamics on energy deposition patterns, and nuclear and Coulomb scattering in the absorbing medium onto loss patterns, the SixTrack and Fluka codes have been coupled, profiting from the best of the refined physical models they respectively embed. The coupling envisages an active exchange of tracked particles between the two codes at each turn, and an on-line aperture check in SixTrack, in order to estimate the local cleaning inefficiency of the system. Knob-like, time-dependent strengths have been implemented in SixTrack, since the designed scraper system foresees the use of a magnetic bump. The study is intended to assess the robustness of the proposed scraper as well as its effectiveness with respect to the desired performance.

WEPFI014	Present Status and Progresses of RFQ of IFMIF/EVEDA	rfq, vacuum, linac, quadrupole	2729
	R. Dima, A. Pepato, F. Scantamburlo, E. Udup INFN- Sez. di Padova, Padova, Italy F. Grespan, A. Palmieri, C. Roncolato INFN/LNL, Legnaro (PD), Italy
	The RFQ of IFMIF/EVEDA is designed to accelerate a 125 mA D⁺ beam from 0.1 MeV to 5 MeV at a frequency of 175 MHz. The production of the modules 16, 17 and 18 necessary has been completed. In this paper the progress and improvements on the production of the modules, as well the development of the brazing procedure design will be described.

WEPFI018	Comparison of High Gradient Performance in Varying Cavity Geometries	damping, vacuum, acceleration, HOM	2741
	T. Higo, T. Abe, Y. Arakida, Y. Higashi, S. Matsumoto, T. Shidara, T. Takatomi, M. Yamanaka KEK, Ibaraki, Japan A. Grudiev, G. Riddone, W. Wuensch CERN, Geneva, Switzerland
	Four types of CLIC prototype TW accelerator structures were high-gradient tested at Nextef, KEK, up to 100 MV/m level and the fifth is under test now. The ramping speed of each processing and the resultant breakdown rate were compared among them. From this comparison, it was found that the ramping speed of the structures with opening ports for HOM damping with magnetic coupling became slow and the resultant breakdown rate became high. It was also found that that with lower surface magnetic field showed faster ramping in processing and lower breakdown rate. This indicates the role of the magnetic field on vacuum breakdowns in copper structure at the region of several tens to 100 MV/m. In this paper, we review the processing stage and the high gradient performance of these structures trying to discuss the relevant parameters, surface electric field, surface magnetic field and other parameters such as Sc, “complex pointing vector”, to the performance difference.

WEPFI040	R&D of C-band Pulse Compression for Soft X-ray FEL at SINAP	cavity, simulation, FEL, klystron	2791
	C.P. Wang, W. Fang, Q. Gu, W.C. Wang, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	A compact Soft X-ray Free Electron Lasers facility is presently being constructed at SINAP, and 8 C-band accelerating structure unit are required for third-stage including 4 pulse compressors. The field mode of C-band SLED is TE0.1.15 with high quality factor Q, and the coupling coefficient is 8.5. Based on the design, the power pulse of klystron is compressed from 2.5μs to 0.5μs, and finally the power gain is about 3.1. In this paper, the details and simulation of 3-dB coupler, mode convertors and the resonant cavities are presented, meanwhile some cold test results of cavity are also analyzed at the end of this paper.

WEPFI044	High Power Test of New SLED System with Biplanar 3-dB Power Divider and Dual Side-wall Coupling Irises for PAL XFEL	klystron, simulation, cavity, free-electron-laser	2803
	Y.D. Joo, H. Heo, W.H. Hwang, H.-S. Lee, K.M. Oh, Y.J. Park PAL, Pohang, Kyungbuk, Republic of Korea
	The new type of the Stanford Linear Accelerator Energy Doubler (SLED) system for the PAL (Pohang Accelerator Laboratory) XFEL (X-ray Free Electron Laser) is developed to be operated with an RF input power of 80 MW and a pulse width of 4 μs. To prevent the RF breakdown such a high power operation, a biplanar 3-dB power divider and dual side-wall coupling irises structure are used in the new SELD system. It is shown that the field gradient and surface current is reduced from that of the original SLED system using the the finite-difference time-domain (FDTD) simulation. The high power test result of the new SLED system in the PAL XFEL test facility will be presented.

WEPFI058	Breakdown Localization Studies on the SwissFEL C-band Test Structures	background, linac, factory, impedance	2824
	J. Klavins, S. Dementjevs, F. Le Pimpec, L. Stingelin, M. Wohlmuther, R. Zennaro PSI, Villigen PSI, Switzerland N.C. Shipman CERN, Geneva, Switzerland
	The SwissFEL main linac will consist of 10⁴ C-band structures with a nominal accelerating gradient of 28MV/m. First power tests were performed on short constant impedance test-structures composed of eleven double-rounded cups. In order to localize breakdowns, two or three acoustic emission sensors were installed on the test-structures. In order to localize breakdowns we have analyzed, in addition to acoustic measurements, the delay and phase of the rf power signals. Parasitic, acoustic noise emitted from the loads of the structure complicated the data interpretation and necessitated appropriate processing of the acoustic signals. The Goals of the experiments were to identify design and manufacturing errors of the structures. The results indicate that breakdowns occur mostly at the input power coupler, as also confirmed by vacuum-events at the same location. The experiments show that the linac test-structures fulfill the requirements in breakdown probability. Moreover developing a detection system based on acoustic emission sensors for breakdown localization for our C-band structure seems reasonable given the results obtained.

WEPFI059	C-band RF Pulse Compressor for SwissFEL	resonance, HOM, cavity, klystron	2827
	R. Zennaro, M. Bopp, A. Citterio, R. Reiser, T. Stapf PSI, Villigen PSI, Switzerland
	The SwissFEL C-band (5.712 GHz) linac consists of 28 RF modules. Each module is composed of a single 50 MW klystron feeding a pulse compressor and four two meter long accelerating structures. The pulse compressor is based on a single Barrel Open Cavity (BOC). The BOC makes use of a “whispering gallery” mode which has an intrinsically high quality factor and operates in resonant rotating wave regime; moreover, and contrary to the conventional SLED scheme, a single cavity is sufficient to define the pulse compressor, without the need for two cavities and a 3-dB hybrid. A prototype has been manufactured and successfully tested. A short description of the BOC is presented, together with the prototype design, production, low level RF measurements, and high power test.

WEPFI060	Planar Balun Design with Advanced Heat Dissipation Structure for kW Level Solid-state Amplifier Module Development	controls, impedance, storage-ring, klystron	2830
	T.-C. Yu, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, Z.L. Liu, C.H. Lo, M.H. Tsai, Ch. Wang, T.-T. Yang, M.-S. Yeh NSRRC, Hsinchu, Taiwan
	The power level of solid-state amplifier is continuously growing for advanced accelerator application as the RF power source. Huge amount of solid-state power amplifier (SSPA) modules can contribute several hundreds of kW RF power with high redundancy and reliability. However, with the increasing desire of RF power of single RF station, too much power modules would adversely cause larger area occupation and higher maintenance cost and complexity. Therefore, with the advancement of the RF power on single SSPA, the overall system design and configuration would become much simple and compact. However, the increasing RF of single SSPA would also bring the thermal problem at its chip as well as the output power combining balun. In this paper, kW range SSPA is developed with the novel planar balun structure with good thermal expansion property. With such new planar balun design, the SSPA can operate stably with above 1kW output RF power.

WEPFI061	Petra Cavity Vacuum RF Condition with Field Balance Mechanism for TPS Storage Ring in NSRRC	cavity, vacuum, controls, storage-ring	2833
	T.-C. Yu, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, Z.L. Liu, C.H. Lo, M.H. Tsai, Ch. Wang, T.-T. Yang, M.-S. Yeh NSRRC, Hsinchu, Taiwan
	In the first stage commissioning of TPS (Taiwan Photon source) storage ring in NSRRC, two room temperature Petra cavities will be used. At this commission stage, 100mA with 950keV beam loss is estimated to have 47.5kW beam loss for each cavity. In the meanwhile, the cavity loss at the specified 1.2MV of each cavity will be about 50kW. Therefore, coupling coefficient of 2 is required. However, the initial design specification of Petra cavity has only beta of about 1.7. Hence, the modification of the input coupler is done with the enhancement of its beta as well as advanced water cooling for some heat point. Besides, due to the two-tuner system of Petra cavity, special field-balance tuner control system is also developed. In RF condition for better vacuum up to 1.4MV, some modification of the tuner mechanical structure is also done to reach high vacuum condition (lower than 5*10^-9 Torr) for storage ring requirement.

WEPFI070	Design of RFQ Coupler for PXIE Project	rfq, simulation, cavity, ion	2854
	S. Kazakov, T.N. Khabiboulline, V. Poloubotko, O. Pronitchev, V.P. Yakovlev Fermilab, Batavia, USA
	Design of new coupler for PXIE RFQ is reported. Two couplers are supposed to deliver ~ 100 kW total CW RF power to RFQ at 162.5 MHz. Coupler has a magnetic loop coupling with the RFQ. Nevertheless it allows to apply a HV bias to suppress a multipactor due to original design of the coupling loop. Results of RF, multipactor and thermal simulations are presented.

WEPFI073	A Modular Cavity for Muon Ionization Cooling R&D	cavity, simulation, vacuum, solenoid	2860
	D.L. Bowring, A.J. DeMello, A.R. Lambert, D. Li, S.P. Virostek, M.S. Zisman LBNL, Berkeley, California, USA C. Adolphsen, L. Ge, A.A. Haase, K.H. Lee, Z. Li, D.W. Martin SLAC, Menlo Park, California, USA D.M. Kaplan Illinois Institute of Technology, Chicago, Illinois, USA T.H. Luo, D.J. Summers UMiss, University, Mississippi, USA A. Moretti, M.A. Palmer, R.J. Pasquinelli, Y. Torun Fermilab, Batavia, USA R.B. Palmer BNL, Upton, Long Island, New York, USA
	The Muon Accelerator Program (MAP) collaboration is developing an ionization cooling channel for muon beams. 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 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 based on a modular pillbox cavity operating at 805 MHz. The modular cavity design allows for the evaluation of different cavity materials - such as beryllium - which may ameliorate or circumvent RF breakdown triggers. Modular cavity components may furthermore be prepared with different surface treatments, such as high-temperature baking or chemical polishing. This poster presents the design and experimental status of the modular cavity, as well as future plans for the experimental program.

WEPFI079	Electromagnetic Modeling of RF Drive in the LANSCE DTL	cavity, DTL, simulation, HOM	2878
	S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	A 3D electromagnetic model of the RF drive module in the LANSCE DTL tank 4 has been developed with the CST MicroWave Studio. The model is explored both with eigensolver and in time domain to evaluate maximal fields in the drive module and RF coupling. Here we describe the model and present simulation results.

WEPFI080	Waveguide Component R&D for the ILC	klystron, linac, cavity, linear-collider	2881
	C.D. Nantista, C. Adolphsen, G.B. Bowden, A.A. Haase, B.D. McKee, F.Y. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515. Several years of effort have gone into refining the design of the International Linear Collider. The direction the design has evolved in response to driving considerations has resulted in a more sophisticated waveguide system for delivering RF power to the cavities. In particular, the desire to eliminate parallel service tunnels along the main linacs led to the proposal of the Klystron Cluster Scheme (KCS), involving plumbing the combined power from groups of klystrons down from the surface at several locations in overmoded waveguide. Additionally, to increase superconducting cavity yield, the acceptance criteria were relaxed to encompass a ±20% range in sustainable operating gradient, which must be accommodated by tailoring of the RF power distribution. Designs and prototype testing of some of the novel waveguide components developed to allow these changes are described here. Christopher Nantista and Chris Adolphsen, “Klystron Cluster Scheme for ILC High Power RF Distribution,” presented at the 2009 Particle Accel. Conf., Vancouver, B.C., Canada, May 2009.

WEPFI081	High Power Tests of Overmoded Waveguide for the ILC Klystron Cluster Scheme	resonance, klystron, linac, simulation	2884
	F.Y. Wang, C. Adolphsen, C.D. Nantista SLAC, Menlo Park, California, USA
	A Klystron Cluster Scheme has been proposed for the ILC Main Linacs in which the output power of up to thirty, 10 MW, 1.3 GHz klystrons are combined in a single, 0.5 m diameter circular waveguide in a surface building and transported down to and along the accelerator tunnel where it is periodically tapped-off to power strings of cavities. This schemes eliminates the need for a separate linac service tunnel and simplifies the linac electric and cooling distribution systems. Recently, a 40 meter long circular waveguide with a coaxial input coupler and a 90 degree rf bend were assembled and run in a resonant configuration to test the concept. With the pipe pressurized with up to 30 psig of N2 to raise the rf breakdown threshold, it was demonstrated that field levels equal to those for the 300 MW transmission required for ILC could be sustained reliably. We report on these and other test results from this program.

WEPFI088	High-power Tests of an Ultra-high Gradient Compact S-band (HGS) Accelerating Structure	vacuum, klystron, monitoring, linac	2902
	L. Faillace, R.B. Agustsson, P. Frigola, A.Y. Murokh, S. Seung RadiaBeam, Santa Monica, USA S.G. Anderson LLNL, Livermore, California, USA V.A. Dolgashev SLAC, Menlo Park, California, USA J.B. Rosenzweig UCLA, Los Angeles, California, USA V. Yakimenko BNL, Upton, Long Island, New York, USA
	RadiaBeam Technologies reports on the RF design, fabrication and high-power tests of a ultra-high gradient S-Band accelerating structure (HGS) operating in the pi-mode at 2.856 GHz. The compact HGS structure offers a drop-in replacement for conventional S-Band linacs in research and industrial applications such as drivers for compact light sources, medical and security systems. The electromagnetic design (optimization of the cell shape in order to maximize RF efficiency and minimize surface fields at very high accelerating gradients) has been carried out with the codes HFSS and SuperFish while the thermal analysis has been performed by using the code ANSYS. The high-power conditioning was carried out at Lawrence Livermore National Laboratory (LLNL).

WEPFI089	High Gradient Normal Conducting Radio-frequency Photoinjector System for Sincrotrone Trieste	gun, cathode, quadrupole, dipole	2905
	L. Faillace, R.B. Agustsson, H. Badakov, P. Frigola RadiaBeam, Santa Monica, USA F. Cianciosi, P. Craievich, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy A. Fukasawa, J.B. Rosenzweig, A. Yakub UCLA, Los Angeles, California, USA
	Radiabeam Technologies, in collaboration with UCLA, presents the development of a high gradient normal conducting radio frequency (NCRF) 1.6 cell photoinjector system for the Sincrotrone Trieste facility. Designed to operate with a 120MV/m accelerating gradient, this single feed, fat lipped racetrack coupler design is modeled after the LCLS photoinjector with a novel demountable cathode which permits cost effective cathode exchange. Full overview of the project to date and installation at Sincrotrone Trieste will be discussed along with basic, design, engineering and manufacturing.

WEPFI092	Multipacting Simulation of the MICE 201 MHz RF Cavity	cavity, solenoid, electron, simulation	2914
	T.H. Luo, D.J. Summers UMiss, University, Mississippi, USA D.L. Bowring, A.J. DeMello, D. Li, P. Pan, S.P. Virostek LBNL, Berkeley, California, USA L. Ge SLAC, Menlo Park, California, USA
	The international Muon Ionization Cooling Experiment (MICE) aims to demonstrate transverse cooling of muon beams by ionization. The MICE ionization cooling channel requires eight 201-MHz normal conducting RF cavities to compensate for the longitudinal beam energy loss in the cooling channel. Multipacting is a resonant electron discharge produced by the synchronization of emitted electrons with the RF fields, which can cause breakdown at high power RF operation. In this paper, we present the study of the multipacting effect in the MICE 201 MHz cavities with the SLAC ACE3P code. The simulation is carried out in the cavity body, the RF coupler region, and the coaxial waveguide, with the external magnetic field from the Coupling Coil. We will identify potential RF breakdowns due to multipacting and propose a solution to suppress them.

WEPME001	SOLEIL Beam Stability Status	feedback, emittance, undulator, electron	2917
	N. Hubert, L. Cassinari, J.-C. Denard, M. Labat, J.-F. Lamarre, A. Nadji, L.S. Nadolski, D. Pédeau, M.-A. Tordeux SOLEIL, Gif-sur-Yvette, France
	This paper reports recent work for improving SOLEIL electron beam stability. X-BPMs from four bending magnet beamline frontends have been inserted in the global orbit feedback loops during user operation. The corresponding source point stabilities have improved and results are reported. Some of the new beamlines request more stringent stability than the existing ones. Their requirements are not only tighter for beam orbit but also for beam size and divergence stability. For these reasons, SOLEIL has decided to define beam quality criteria for each sensitive beamline. Then it can predict ahead of commissioning how well the beamline will likely perform. A feedback on the vertical emittance, measured by a pinhole camera, has been introduced in order to reduce beam size and divergence variations due to magnetic configuration changes of a few insertion devices.

WEPME015	Evaluation of the Superconducting LLRF system at cERL in KEK	LLRF, cavity, controls, linac	2956
	F. Qiu, D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura, T. Miyajima, K. Tsuchiya KEK, Ibaraki, Japan
	A low level RF (LLRF) design is being currently developed within the compact Energy Recover Linac (cERL) at KEK. One challenging task is to achieve the high amplitude and high phase stability required by the accelerating fields of up to 0.1% and 0.1°, respectively. To improve the performance of the LLRF system, a gain scanning experiment for determining the optimal controller gain was carried out on the cERL. Furthermore, as a substitute for the traditional PI controller, a more robust H∞-based multiple input multiple output (MIMO) controller was realized. This controller requires more detailed system information (transfer function or state equation), which can be acquired by using modern system identification methods. In this paper, we describe the current status of these experiments on the cERL.

WEPME058	Integrated System Modeling Analysis of a Multi-cell Deflecting-mode Cavity in Cryogenic Operation	cavity, simulation, cryomodule, vacuum	3064
	Y.-M. Shin, M.D. Church, J. Ruan Fermilab, Batavia, USA
	Over the past decade, multi-cell deflecting (TM110) mode cavities have been employed for experiments on six-dimensional phase-space beam manipulation ,,,,**** at the A0 Photo-Injector Lab (16 MeV) in Fermilab and their extended applications with vacuum cryomodules are currently scheduled at the Advanced Superconducting Test Accelerator (ASTA) user facility (> 50 MeV). Despite the successful test results, the cavity, however, demonstrated limited RF performance during liquid nitrogen (LN2) ambient operation that was inferior to theoretic prediction. We thus fully inspected the cavity design with theoretical calculation (based on Panofsky-Wenzel theorem) combined with RF simulations. Also, we are extensively developing an integrated computational tool with comprehensive system analysis capacity to solve complex thermodynamics and mechanical stresses of a high-Q deflecting-mode cryomodule. We will benchmark simulation analysis result with experimental data from high power RF tests in Fermilab. Successfully developed modeling tool will be potentially used for prompt assessment on RF performance of vacuum-cryomodules. * D. A. Edwards, LINAC 2002 Y.-E Sun, PRTAB 2004 * P. Piot, PRSTAB2006 ** J. Ruand et al., PRL 2011 *** Y.-E. Sun, et al., PRL 2010

WEPME061	A Wideband Slotted Kicker Design for SPS Transverse Intra-bunch Feedback	kicker, impedance, feedback, simulation	3073
	J.M. Cesaratto, J.D. Fox, C.H. Rivetta SLAC, Menlo Park, California, USA D. Alesini, A. Drago, A. Gallo, F. Marcellini, M. Zobov INFN/LNF, Frascati (Roma), Italy S. De Santis LBNL, Berkeley, California, USA W. Höfle CERN, Geneva, Switzerland
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP) and by the EU FP7 HiLumi LHC - Grant Agreement 284404. Control and mitigation of transverse beam instabilities caused by electron cloud and TMCI will be essential for the SPS to meet the beam intensity demands for the HL-LHC upgrade. A wideband intra-bunch feedback method is in development, based on a 4 GS/s data acquisition and processing, and with a back end frequency structure extending to 1 GHz. A slotted type kicker, similar to those used for stochastic cooling, has been considered as the terminal element of the feedback chain. It offers the most promising deflecting structure characteristics to meet the system requirements in terms of bandwidth, shunt impedance, and beam coupling impedance. Different types of slotted structures have been explored and simulated, including a ridged waveguide and coaxial type waveguide. In this paper we present our findings and the conceptual design of a vertical SPS wideband kicker consistent with the stay clear, vacuum, frequency band coverage, and peak shunt impedance requirements.

THPEA043	An Equipment Hub for Managing a Small Town and a Complex Machine	radiation, controls, status, collider	3237
	P. Martel, A. Alexandre Metola, Ch. Delamare, M.P. Kepinski, S. Mallon Amerigo, L. Pater, S. Petit, D. Widegren CERN, Geneva, Switzerland
	Effective maintenance of the accelerators’ complex is vital for CERN’s mission. While this work is highly dependent on operational planning and constraints, it also needs to be coordinated with the maintenance of the infrastructure where the complex is embedded. The nature and degree of the logistics problems that arise from this interdependence cannot be handled by partial, decoupled solutions from each of the stakeholders. CERN’s Enterprise Asset Management system is the central hub where all relevant data about equipment and its maintenance is kept. It is also where data and documents about the manufacturing, installation, safety inspection, radiation measurements, disposal, etc. of the scientific equipment reside. This hub allows the effective sharing of consistent equipment data, accessed by a large number of people and systems, and supplies a wide range of interfaces – ranging from the user in the field with no access to a desktop computer, to scheduling systems that need to interact with it through Web services; this is achieved by means of a series of systems, tools and mechanisms, all dedicated to different needs but working on the same data and sharing common policies.

THPFI014	Bellows with a New RF Shield Made of Metal Braid for High Intensity Proton Accelerators	impedance, vacuum, background, synchrotron	3321
	N. Ogiwara, J. Kamiya, M. Kinsho, Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan O. Koizumi Sun-Tech limited, Kobe, Japan
	In the 3 GeV-RCS (Rapid cycling Synchrotron) in J-PARC (Japan Accelerator Research Complex) project, large-scale hydro-formed bellows were developed to adjust the gap between the ceramic ducts and/or between the ceramic ducts and the transport ducts. They have been equipped with a newly developed RF shield, because the usual beryllium-copper spring finger contacts were found to be very hard (roughly 1000 N/mm) owing to the large size. This contact is made of Ti braid, which consists of wires with a diameter of 0.3 mm. This RF contact is a kind of basket (with two ports) made with the braids. Because of the spring effect, the contact can change shape easily. In addition, the contact can easily connect the different cross sections in a smooth fashion. Furthermore, this structure is almost free from the dust generation, which is one of the most troublesome problems for the usual spring finger contacts. This time, we have constructed reserve bellows with the RF shield made of SUS 316L wires to improve the reliability of user operation. The outline of the bellows will be presented, especially laying emphasis on the mechanical function of the RF shield.

THPFI023	A Newly Developed High Directivity X-band Waveguide Directional Coupler	simulation, insertion, pick-up, vacuum	3345
	X. He, X. Wang, F. Zhao IHEP, Beijing, People's Republic of China
	A new X-band waveguide directional coupler working at 11.9924 GHZ is designed. Four holes symmetrical to the structure is drilled along the central line of the narrow-wall, which is used to couple the electromagnetic power from the main-waveguide to the sub-waveguide. The final prototype has got a measurement result of 32.2 dB Directivity (-47.0 dB Coupling Degree) together with a very low VSWR (1.067) and Insertion Loss (-0.11 dB) at 11.9924 GHz. The vacuum performance is also qualified.

THPFI051	Radio-Frequency Multipacting as Quality Control of Coatings for e-Cloud Suppression	dipole, electron, resonance, vacuum	3403
	P. Costa Pinto, J. Bauche, S. Calatroni, F. Caspers, P. Edwards, M. Holz, M. Taborelli CERN, Geneva, Switzerland
	To mitigate electron clouds in particle accelerators, a carbon coating with low SEY has been developed. In the case of the SPS (Super Proton Synchrotron), which belongs to the LHC injector chain, testing the performance of coated beam pipes directly in the accelerator must cope with the schedule of the regular machine operation. For this reason an alternative instrument based on RF induced multipacting in a coaxial configuration has been designed for ex-situ characterization of the main bending dipoles of the SPS. In this contribution we report the results obtained before and after coating for two 6.4 meter dipoles with different cross sections of the vacuum chambers. The multipacting is monitored by measuring the pressure rise and the RF reflected power. After coating, the power threshold to induce multipacting is strongly reduced indicating a lower propensity for electron cloud. The impact of the RF coupling on the sensitivity of the technique is discussed.

THPFI057	Development of Vacuum Chamber in Low Z Material	vacuum, radiation, impedance, background	3421
	C. Garion, P. Costa Pinto, M.A. Gallilee, J. Perez Espinos CERN, Geneva, Switzerland
	Highly transparent vacuum chambers are more and more required in high energy particle physics. In particular, vacuum chambers in the experiments should be as transparent as possible to minimize the background to the detectors while reducing also the material activation. Beryllium is, so far, the most performing material for this application, but it presents some drawbacks such as brittleness, manufacturing issues, toxic hazard, high cost and low availability. A development work to obtain alternative material to the beryllium with similar performance is being carried out at CERN. Three categories have been defined and considered: raw bulk material, material and structural composites. Main requirements are the vacuum compatibility: leak tightness, low outgassing rate, temperature resistance (in the range 200-230 °C), transparency, and mechanical stiffness and strength. Carbon is the element with the lowest atomic number after beryllium and that is appropriate for this application. Therefore carbon based materials have been considered in a variety of options. In this paper, several technologies are presented and discussed. Results of preliminary tests on samples are also shown.

THPME048	Assembly and Test of a Modified Spectrometer Solenoid for MICE	solenoid, radiation, target, controls	3621
	S.P. Virostek, D. Li, P. Pan, S. Prestemon LBNL, Berkeley, California, USA R. Preece STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	Funding: This work is supported by the Office of Science, US-DOE under DOE contract DE-AC02-05CH11231. The MICE superconducting spectrometer solenoids have been modified and rebuilt as a result of the testing done in 2008, 2009 and 2010. The number of two-stage cryocoolers was increased from three in 2009 to five in the modified magnet. The new shield for the spectrometer solenoid is fabricated primarily from 1100-O aluminum instead of 6061-T6 aluminum used in the former versions of the magnet. The thermal connection between the shield and the first-stage of the cold heads has been improved to reduce the temperature drop between the shield and the coolers. As a result of these changes, the first-stage temperatures for the coolers are below 45K, which resulted in an increase in the refrigeration generated by the cooler second stages. The quench protection system has been altered in order to provide additional protection to the magnet in the event of a lead failure between the magnet power supply and the magnet coils. The quality of the shield and cold mass MLI wrap has also been improved. Details of the modifications and test results demonstrating improved magnet performance are presented in this paper.

THPWA018	High Power Test of a C-band 6 MeV Standing-wave Linear Accelerator	target, radiation, brightness, gun	3666
	J.H. Shao, H.B. Chen, Y.-C. Du, Q.X. Jin, J. Shi, H. Zha TUB, Beijing, People's Republic of China
	A C-band 6MeV standing-wave bi-periodic on-axis coupled linear accelerator has been developed at the accelerator laboratory of Tsinghua University [1,2]. In the recent high power RF test, the capture ratio, the energy spectrum, the spot size and the dose rate of this accelerator have been measured. With a 2.07-MW input power, the peak current is 130mA and the output spot root-mean-square diameter is about 0.8mm. The output kinetic energy is 6.0MeV with a spectrum FWHM of 7.5%. In this paper, the setup and detailed results of the high power RF test are presented.

THPWA030	Design and Prototype Test of C-band Standing-wave Accelerating Structure to Enhance RF Phase Focusing	electron, focusing, bunching, simulation	3690
	H. Yang, M.-H. Cho, W. Namkung, S.-G. Shin POSTECH, Pohang, Kyungbuk, Republic of Korea S.H. Kim ANL, Argonne, USA J.-S. Oh NFRI, Daejon, Republic of Korea
	Funding: This research was financially supported by the MOTIV, KIAT and Dongnam Institute for Regional Program Evaluation through the Leading Industry Development for Economic Region A C-band standing-wave accelerator for X-ray and electron beam sources of medical radiotherapy is designed and being fabricated. The accelerator system is to be operated in two modes, using the X-ray and electron beams. Because of the energy loss in electron mode, the accelerator is capable of producing 6-MeV, 100-mA electron beams with peak 2-MW RF power, and 7.5-MeV, 20 mA electron beams with peak 2.5-MW RF power. The beam radius at the end of column was < 0.5 mm without focusing magnets in PARMELA simulations, because the bunching cells are designed to enhance the RF phase focusing. Each cavity in the bunching and normal cells was designed by the MWS code to maximize the effective shunt impedance with 3.8% inter-cell coupling in normal cells. The dimensions of normal cells were determined by the low power RF test of prototype cells with 5711.06-MHz resonant frequency and 3.5% inter-cell coupling. In this paper, we present details of the accelerator design and prototype test.

THPWO004	RF Tuning of the LINAC4 RFQ	rfq, linac, quadrupole, dipole	3761
	O. Piquet, Y. Le Noa, J. Novo CEA/DSM/IRFU, France M. Desmons, A. France CEA/IRFU, Gif-sur-Yvette, France C. Rossi CERN, Geneva, Switzerland
	The construction of Linac4, the new 160 MeV CERN H⁻ injector, has started with the goal of improving the LHC injection chain with a new higher energy linac. The low energy front end of Linac4 is based on a 352 MHz, 3-m long Radiofrequency Quadrupole (RFQ) which accelerates the 70 mA, 45 keV H⁻ beam from the ion source to the energy of 3 MeV. The RFQ, made of three modules, one meter each, is of the four-vane type and it has been designed in collaboration between CERN and CEA. Construction has started in 2009 and all the steps of machining and assembly have been done at CERN. The RFQ is equipped with 35 fixed tuners and one waveguide RF port located in the second module. This paper describes the procedure used to tune the accelerating field and the power coupler of the LINAC4 RFQ in order to achieve the nominal voltage profile within ±1% accuracy.

THPWO015	First Coupled CH Power Cavity for the FAIR Proton Injector	cavity, linac, proton, alignment	3791
	R. M. Brodhage, U. Ratzinger IAP, Frankfurt am Main, Germany G. Clemente, W. Vinzenz GSI, Darmstadt, 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 Summer 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. Before Spring 2013 the final drift tube structure will be welded inside the main tanks and the preparation for copper plating will take 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.

THPWO041	The development of a high power input coupler for China ADS injector I RFQ	rfq, cavity, vacuum, injection	3857
	T.M. Huang, X. Chen, R. Guo, H.Y. Lin, Q. Ma, F. Meng, H.F. Ouyang, W.M. Pan, X.H. Peng, Z. Zhang, G.Y. Zhao IHEP, Beijing, People's Republic of China
	A 325 MHz RFQ is designed to accelerate a beam current of 15 mA in CW mode with injection energy of 35 keV and output energy of 3.2 MeV for China Accelerator Driven sub-critical System (ADS) injector I. Total RF power of 320 kW has to be delivered into the RFQ cavity. For reliable operation, four input couplers are adopted to share the driven power. A coaxial loop type input coupler is developed. The coupler features a Tristan type RF window, a doorknob to realize the transition from a half-height WR2300 waveguide to a coaxial line and a coaxial line with a coupling antenna loop. Two prototypes of the window and inner conductor assemblies have been fabricated and received high power test. The prototypes were tested up to 100 kW CW RF power in traveling wave mode. This paper will describe the design, fabrication and high power test of the coupler in details.

FRXAA01	Beam Dynamics and Collective Effects in "Ultimate" Storage Rings	emittance, ion, electron, scattering	3981
	M. Takao JASRI/SPring-8, Hyogo-ken, Japan
	This presentation will review the beam dynamics issues such as impedance driven instabilities, intrabeam scattering, and the Touschek lifetime in ultimate storage rings with very low emittance.
	Slides FRXAA01 [11.245 MB]

Paper

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Other Keywords

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MOPEA071

Operating the Diamond Storage Ring with Reduced Vertical Emittance

feedback, emittance, target, storage-ring

249

I.P.S. Martin, M.G. Abbott, M. Apollonio, R. Bartolini, D. Hickin
Diamond, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom

In a synchrotron radiation light source, a reduction in vertical emittance can potentially increase the source brightness, reduce the spot size for microfocus beam lines or increase the vertical transverse coherence of the photon beam. With this aim, the target vertical emittance for the Diamond storage ring has been recently reduced from 27pm.rad to 8pm.rad (0.3% coupling). In this paper we discuss the main impacts of this reduction, along with the steps that have been taken to stabilise the coupling at the new value.

MOPFI053

Upgrades of the SPS, Transfer Line and LHC Injection Protection Devices for the HL-LHC Era

injection, vacuum, kicker, extraction

401

Ö. Mete, O. Aberle, F. Cerutti, K. Cornelis, B. Goddard, V. Kain, R. Losito, F.L. Maciariello, M. Meddahi, A. Mereghetti, J.A. Uythoven, F.M. Velotti
CERN, Geneva, Switzerland
E. Gianfelice-Wendt
Fermilab, Batavia, USA

The challenging High Luminosity LHC (HL-LHC) beam requirements will lead in the future to unprecedented beam parameters along the LHC injector chain. In the SPS accelerator these requests translate into about a factor two higher intensity and brightness than the present design performance. In addition to the challenge of producing and accelerating such beams, these parameters affect the resistance of the existing equipment against beam impact. Most of the protection devices in the SPS ring, its transfer lines and the LHC injection areas will be put under operational constraints which are beyond their design specification. The equipment concerned has been reviewed and their resistance to the HL-LHC beams checked. Theoretical and simulation studies have been performed for the SPS beam scraping system, the protection devices and the dump absorbers of the SPS-to-LHC transfer lines, as well as for the LHC injection protection devices. The first results of these studies are reported, together with the future prospects.

MOPME041

Design and Calculation of the Stripline Beam Position Monitor for HLS II Storage Ring

quadrupole, simulation, storage-ring, impedance

562

F.F. Wu, C. Cheng, W.B. Li, P. Lu, T.J. Ma, B.G. Sun, H. Xu, Y.L. Yang, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by the National Science Foundation of China (10875117, 11005105, 11175173)
According to the requirements of HLS II upgraded, in order to acquire the non-intercepting measurement of beam position and quadrupole component, a new stripline beam position monitor (BPM) was designed for storage ring. The BPM parameters were optimized to acquire impedence matching with characteristic impedance of the external transmission lines and the coupling coefficients between the electrodes were calculated. According to the difference/sum and log-ratio methods, the horizontal and vertical sensitivities, mapping figures and fitting polynomials wered acquired. The results showed that sensitivities using log-ratio method were bigger than those using difference/sum method. The sum signal was also simulated when beam displacement varied from (0 mm, 0 mm) to (5 mm, 5 mm), the result showed that the variation of normalized sum signal was no more than ±6%. The gaussian weighted method of a two-dimensional grid structure was used to simulate the gaussian bunch and simulate the beam transverse quadrupole component changing with position (x, y), the result showed that the beam transverse quadrupole component changed linearly with position combination (x2-y2).

MOPME043

Calibration of Beam Position Monitors in the Injector of HLS II

quadrupole, brilliance, linac, emittance

568

J.Y. Zou, J. Fang, W.B. Li, P. Lu, T.J. Ma, B.G. Sun, Y.L. Yang, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by the National Science Foundation of China (11175173, 11105141)
A beam position monitor(BPM) system is being installed to improve the beam position measurement of the injector at the upgrade project of Hefei Light Source (HLS II). The new BPM system is consists of 19 stripline BPMs and 19 Libera Brilliance Single Pass modules. Before installation, the response of the BPMs must be mapped to improve the accuracy of measurement. The theoretical equations of both position and quadrupole component of the BPM are calculated first, using both formula and matlab simulation. A laboratory calibration system is built. The inconsistency of Libera Brilliance Single Pass channels is measured to improve the accuracy of calibration. The calibrating results show the position sensitivity is less than 5% difference compare to the theoretical value, while the quadrupole component sensitivity is less than 10% difference.

MOPME046

Preliminary Experimental Results of Axial B-dot Measuring Beam Tilt

high-voltage, simulation, dipole, impedance

577

X. He, Q. Li, C. Ma, J. Pang, L. Zhao
CAEP/IFP, Mainyang, Sichuan, People's Republic of China

Funding: This work is under the support of NSFC project No. 11175166
Beam monitors sensitive to the beam's azimuthal B-dot field (sometimes referred as B-dots) are widly used to measure the displacement of beam centroid, as the beam generates a dipole term of the azimuthal magnetic field. The authors have pointd out that the similar B-dots sensitive to axial magnetic field can be used to measure the beam tilt directly in earlier work. A monitor which consists of four azimuthal B-dots and four axial B-dos is designed and fabricated. The monitor was tested on a coaxial calibration stand, which has a character resistance of 50 Ohm. Two position tuners are installed on the calibration stand, to adjust the position and the tilt of the inner conductor. Experiments show that the axial B-dot monitor can be successfully used to measure the tilt of the inner conductor directly.

MOPME047

Simulation of a Beam Angel Monitor using the Axial B-dot Field

simulation, monitoring, induction, dipole

580

J. Pang, X. He, Q. Li, C. Ma
CAEP/IFP, Mainyang, Sichuan, People's Republic of China

Funding: The National Natural Science Foundation of China
A beam angel monitor using the axial B-dot field was presented recently while the one using azimuthal B-dot field had been widely employed to measure the beam positions for more than ten years. Basing on the principle of the proportionality between the deflection angel and the difference of axial B field with corresponding positions, the axial B-dot monitor has a potential use for beam deflection angle measurement directly. A test stand was built to test and improve the axial B-dot monitor, which is fabricated as a PCB structure. Meanwhile, simulations using the CST MWS code have been performed, demonstrating a good agreement to the test results and giving some advice to suppress the disturbance of position deviation of the beam.

MOPME051

Development of Cavity Beam Position Monitor System

cavity, FEL, simulation, electron

586

B.P. Wang, Y.B. Leng, Y.B. Yan, L.Y. Yu, R.X. Yuan, W.M. Zhou
SINAP, Shanghai, People's Republic of China

Shanghai soft X-ray free electron laser (SXFEL) facility requires beam position resolution better than 1 μm in the undulator sections. Cavity BPM system, feasible in obtaining sub micron position resolution, has been developed to achieve the goal. Two cavity prototypes with high Q and low Q were designed and fabricated. The relevant dedicated electronic, which could cover the two types of cavity BPMs, also have been developed. Fast fourier transform (FFT) and digital down converted based algorithms were implemented. The beam test of the whole system has been scheduled on the Shanghai deep ultraviolet (SDUV) FEL facility. The cavity design, electronic architecture, achieved performance during beam test will be presented.

MOPME076

Determination of Octupole and Sextupole Polarities in the LHC

octupole, sextupole, injection, lattice

655

M.J. McAteer, Y.I. Levinsen, E.H. Maclean, T. Persson, P.K. Skowroński, R.J. Steinhagen, R. Tomás
CERN, Geneva, Switzerland

We report the results of measurements to verify the polarity of the LHC’s lattice focusing and defocusing octupoles (MOF and MOD), spool piece octupole correctors (MCO), arc skew sextupole correctors (MSS), and interaction region sextupoles (MCSX and MCSSX). Octupole polarities were determined by measuring the change to second order chromaticity when a magnet family was trimmed. The MSS skew sextupole corrector polarities were checked by measuring the change to chromatic coupling when a magnet family was trimmed. The polarities of the MCSSX skew sextupoles in IR 1 and the MCSX normal sextupoles in IR 5 were checked by measuring the tune shift due to a magnet trim. Comparison of measurements with model predictions indicates that the polarities of the octupoles and the IR sextupoles are correct, and the polarities of the MSS skew sextupole correctors are reversed.

MOPWA023

A Low Jitter Pulse Generator Based on Two-stage Storage Module

pulsed-power, simulation, controls, high-voltage

711

J.N. Li, W.Q. Chen, F. Guo, W. Jia
NINT, Xi'an, People's Republic of China

A scheme for a low jitter pulse generator based on two-stage storage module is described. The thyristor is used for the first stage of the generator, the UV-illumination gas switch is used for the second stage of the generator. Between them, the pulsed transformer is used for connecting. A capacitance-resistance coupling structure was designed to produce UV light which triggered the switch to decrease the breakdown jitter. The test result shows, the risetime of the current is 0.73μs, the peak value of the current is 1.8kA on 1.1Ω load. The delay of the generator is 35.1μs, and the jitter of the generator attaches to 0.22μs.

MOPWA033

Modelling of Parasitic Inductances of a High Precision Inductive Adder for CLIC

impedance, kicker, damping, emittance

738

J. Holma, M.J. Barnes
CERN, Geneva, Switzerland
S.J. Ovaska
Aalto University, School of Science and Technology, Aalto, Finland

The CLIC study is exploring the scheme for an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The CLIC pre-damping rings and damping rings will produce, through synchrotron radiation, ultra-low emittance beam with high bunch charge. To avoid beam emittance increase, the damping ring kicker systems must provide extremely flat, high-voltage, pulses. The specifications for the extraction kickers of the DRs are particularly demanding: the flat-top of the pulses must be ±12.5 kV with a combined ripple and droop of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising approach to meeting the specifications. However, the output impedance of the inductive adder needs to be well matched to the system impedance. The primary leakage inductance, which cannot be computed accurately analytically, has a significant effect upon the output impedance of the inductive adder. This paper presents predictions, obtained by modelling the 3D geometry of the adder structure and printed circuit boards using the FastHenry code, for primary leakage inductance.

MOPWA070

Beam Position Monitor within the Cornell Energy Recovery Linac Cavity Assembly

HOM, pick-up, RF-structure, cavity

840

M.G. Billing, M. Liepe, V.D. Shemelin, N.R.A. Valles
CLASSE, Ithaca, New York, USA

In an energy recovery Linac (ERL) the low energy beam is very sensitive to deflections due to the RF fields as it passes through the accelerator cavities. Therefore, to avoid the possible effects of beam breakup, it will be important to determine the optimum transverse position for the beam within the first several sets of cavity cells in the cryostat assembly and to maintain this position over long periods. As a result a beam position monitor (BPM) has been designed to be located between the higher-order modes (HOM) loads and the seven-cell RF structures. This BPM’s design reduces the coupling of RF power from the fundamental mode and HOMs into the BPM, while maintaining acceptable position sensitivity and resolution. We analyzed the coupling of the probe to the HOMs of realistically shaped cavities by generating geometries for hundreds of cavities having small shape variations from the nominal dimensions consistent with present machining tolerances, and solved for their monopole and dipole spectra. Our results show that the peak, dissipated power within BPM cables, which pass through the cryostat, is well within the permissible levels.

MOPWO023

Upgrade and Systematic Measurement Campaign of the ATF2 Multi-OTR System

target, emittance, wakefield, extraction

933

A. Faus-Golfe, J. Alabau-Gonzalvo, C. Blanch Gutierrez, J. Resta-López
IFIC, Valencia, Spain
J. Cruz, E. Marín, D.J. McCormick, G.R. White, M. Woodley
SLAC, Menlo Park, California, USA

A multi-Optical Transition Radiation (mOTR) system made of four stations is being used routinely since September 2011 for transverse beam size measurement and emittance reconstruction in the extraction line of ATF2, providing diagnostic support during the ATF2 tuning operation. Furthermore it is also an excellent tool for fast transverse coupling correction. Due to the compactness of the current design the system has an influence in the increase of the transverse emittance due to wakefield effects when a simultaneous measurement is made. To avoid this effect a new target holder and a new optics has been designed and implemented. In this paper we describe the present status of the ATF2 mOTR system, showing recent performance results, and hardware design improvements.

MOPWO061

Numerical Approaches for Simulation of Stochastic Cooling in 2D Phase Space

emittance, simulation, electromagnetic-fields, storage-ring

1028

M. Dolinska
NASU/INR, Kiev, Ukraine
C. Dimopoulou, A. Dolinskyy, F. Nolden
GSI, Darmstadt, Germany

A consolidated fluid-dynamics algorithm for the analysis of beam dynamics under the influence of the electromagnetic field is presented. Aiming at simulating stochastic cooling of particle beams in 2D space, two numerical algorithms solving the 2D Fokker-Planck Equation are described. As an alternative approach, a numerical method based on the macro-particle tracking turn in turn in the ring (i.e. in the time domain) is introduced. Some results of the simulation of the stochastic cooling in the Collector Ring by both methods are discussed.

TUODB103

Recent Results from CesrTA Intrabeam Scattering Investigations

emittance, simulation, damping, scattering

1126

M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, D. Sagan, J.P. Shanks, S. Wang
CLASSE, Ithaca, New York, USA

Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505.
Manifestation of intrabeam scattering (IBS) in an electron/positron storage ring depends on the radiation damping time in two ways. First, the beam size is the equilibrium of the IBS growth rate in each of the three degrees of freedom and corresponding damping rates. Second, scattering events that occur less frequently than order once per damping time contribute to non-Gaussian tails that are invisible to our beam size monitors. The tail cut procedure excludes these relatively rare events in the calculation of equilibrium beam size. In machines with short damping times, the tail cut significantly reduces the effective IBS growth rate. At CesrTA, we measure the dependence of beam size on bunch charge in IBS-dominated beams. We vary the vertical emittance using a closed optics bump that increases the vertical dispersion and transverse coupling in the wiggler regions. Measurements are taken at both 2.1 and 2.3 GeV. Here we report the results of these experiments and compare those results to theory.

Slides TUODB103 [1.221 MB]

TUPEA012

Rebunching Ultracold Neutrons by Magnetic Deceleration for the neutron EDM experiment at J-PARC

neutron, resonance, power-supply, focusing

1187

S. Imajo
Kyoto University, Kyoto, Japan
Y. Arimoto
KEK, Ibaraki, Japan
P.W. Geltenbort
ILL, Grenoble, France
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
M. Kitaguchi
Kyoto University, Research Reactor Institute, Osaka, Japan
Y. Seki
RIKEN Nishina Center, Wako, Japan
H.M. Shimizu
Nagoya University, Nagoya, Japan
T. Yoshioka
Kyushu University, Fukuoka, Japan

Ultra cold neutrons (UCN) - neutrons with energies less than 300 neV - can be accelerated or decelerated by means of static magnetic and RF fields. Neutron have a magnetic dipole moment, and hence their kinetic energies vary depending on their spin in magnetic fields. Their kinetic energies are restored when they get out from the magnetic field area if their spin did not flip. A spin flip can be triggered by applying an RF field whose frequency coincides with the spin precession frequency of a neutron in this magnetic field. This allows to tune the kinetic energy of neutrons. This method can be used to rebunch a pulsed beam of neutrons to a storage bottle that can store UCN. By open and close the storage bottle synchronously with the rebuncher, high UCN densities can be achieved for precision measurements of neutron properties such as the Electric Dipole Moment. The method and experimental setup are described in detail and the results of a recent first test experiments are presented.

TUPEA079

Experimental Search For Acceleration in the Micro-accelerator Platform

laser, electron, acceleration, vacuum

1307

J.C. McNeur, K.S. Hazra, B. Matthews, E.B. Sozer, G. Travish
UCLA, Los Angeles, USA
R.J. England, B. Montazeri, K. Soong, Z. Wu
SLAC, Menlo Park, California, USA
E.A. Peralta
Stanford University, Stanford, California, USA
R.B. Yoder
Goucher College, Baltimore, USA

The results of recent experimental efforts to observe acceleration in the Micro-Accelerator Platform (MAP) are detailed. The MAP is a slab-symmetric dielectric laser accelerator that when side illuminated by an optical laser, accelerates electrons via a standing wave resonance. This structure has been placed in the beamline at the NLCTA experimental hall at SLAC. A 60 MeV electron beam traverses the MAP when it is illuminated by a laser and, using a camera placed around a spectrometer bend magnet, signs of acceleration in the energy spectrum of the beam are searched for. The details of this search, as well as simulations that motivate the search, are elaborated on below.

TUPFI039

Optics Performance of the LHC During the 2012 Run

optics, sextupole, quadrupole, octupole

1433

P. Skowroński, T. Bach, M. Giovannozzi, A. Langner, Y.I. Levinsen, E.H. Maclean, T. Persson, S. Redaelli, T. Risselada, M. Solfaroli Camillocci, R. Tomás, G. Vanbavinckhove
CERN, Geneva, Switzerland
M.J. McAteer
The University of Texas at Austin, Austin, USA
R. Miyamoto
ESS, Lund, Sweden
T. Persson
Chalmers University of Technology, Chalmers Tekniska Högskola, Gothenburg, Sweden

During 2012 the LHC was operating at 4TeV with beta star at ATLAS and CMS interaction points of 0.6m. During dedicated machine studies the nominal LHC optics was also setup with beta star of 0.4m. A huge effort was put into the optics commissioning leading to a record low peak beta-beating of around 7%. We describe the correction procedures and discuss the measurement results.

TUPFI065

Muon Ionization Cooling Experiment Step VI

cavity, emittance, vacuum, status

1499

D. Rajaram
Illinois Institute of Technology, Chicago, Illinois, USA
P. Snopok
IIT, Chicago, Illinois, USA

The Muon Ionization Cooling Experiment (MICE) is a demonstration experiment to prove the viability of cooling a beam of muons for use in a Neutrino Factory and Muon Collider. The ultimate Step VI configuration of the MICE cooling channel, a section of the one proposed in the Neutrino Factory Study II, will demonstrate a 10% reduction in transverse beam emittance measured at the level of 1%. This requires measuring emittance to 0.1%. This measurement will be made using all beam line elements present in the MICE Step IV configuration with the addition of two low-Z absorber modules and two RF-Coupling Coil (RFCC) modules. The RFCC modules each contain four normal-conducting low frequency (201 MHz) RF cavities with a guiding magnetic field provided by a large diameter coupling coil. Each of these cavities will require approximately 1 MW of RF power in a 1 ms pulse at a rate of 1 Hz. The experiment can explore a variety of combinations of momentum, beta function, magnetic field flip or non-flip configurations that will prove precious in the design of future cooling channels. The current status and progress toward Step VI are discussed.

TUPME012

Space Charge Simulation based on a Measured Optics in J-PARC MR

optics, space-charge, resonance, sextupole

1589

K. Ohmi, S. Igarashi, Y. Sato, J. Takano
KEK, Ibaraki, Japan
S. Hatakeyama
JAEA/J-PARC, Tokai-mura, Japan

Linear optics parameters, beta, alpha, phase, x-y coupling and dispersion are measured by phase space monitor and/or other tools. Nonlinear effects due to the space charge and magnets are dominantly determined by linear optics. For example, the beam distribution is mainly determined by linear optics, and error of beta function at a sextuple magnet is larger than error of magnet strength generally. This means space charge simulation based on the measured optics takes into account of the major part of errors. We discuss how beam loss degrade and which resonances are induced by the errors in the simulations.

TUPME030

Emittance Reconstruction from Measured Beam Sizes

emittance, simulation, optics, FEL

1640

J. Giner Navarro, A. Faus-Golfe, J. Fuentes, J. Navarro, J. Resta
IFIC, Valencia, Spain

In this paper we analyze the projected emittance (2D) and the intrinsic emittance (4D) reconstruction method by using the beam size measurements at different locations. We have studied analytically the conditions of solvability of the systems of equations involved in this process and we have obtained some rules about the locations of the measurement stations to avoid unphysical results. Presently, simulations are being made to test the robustness of the algorithm in realistic scenarios with high coupling and measurement errors. The special case of a multi-OTR system in ATF2 is being studied in much detail. The results of these studies will be very useful to better determine the location of the emittance measurement stations in the diagnostic sections of Future Linear Colliders.

TUPME033

Evaluation of the Beam Coupling Impedance of New beam Screen Designs for the LHC Injection Kicker Magnets

impedance, kicker, injection, resonance

1649

H.A. Day
UMAN, Manchester, United Kingdom
M.J. Barnes, F. Caspers, E. Métral, B. Salvant
CERN, Geneva, Switzerland
R.M. Jones
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The LHC injection kicker magnets (MKIs) have experienced a significant degree of beam induced heating since the beginning of the 2011 due to the increasing intensity stored in the LHC, for long periods of time, and the relatively large broadband impedance of the installed kicker magnets. In this paper we show the sources of impedance in the MKIs, especially the effect that the beam screen dimensions have on the impedance. We show how these alter the power loss, and present an improved beam screen design that improves shielding on the magnet, whilst further improving electrical breakdown.

TUPME052

Sub-harmonic Buncher Design for the CLIC Drive Beam Injector

beam-loading, electron, linear-collider, collider

1685

H. Shaker, S. Döbert, R. Leuxe, S. Sanaye Hajari
CERN, Geneva, Switzerland
L. Dassa
Università di Brescia, Brescia, Italy
S. Sanaye Hajari, H. Shaker
IPM, Tehran, Iran

The CLIC (Compact LInear Collider) is based on two beam concept where a high current drive beam provides the energy needed for acceleration of the main beam. The CLIC drive beam accelerator starts with a high current injector using a sophisticated sub-harmonic bunching system. This paper will focus on the design of the Sub Harmonic Bunchers (SHBs) the first RF components of the injector. A backward traveling wave structure has been optimized for this task. It will be shown also how to avoid asymmetrical fields inside the coupler cells and how to compensate beam loading by changing the phase velocity in comparison to the beam velocity.

TUPME065

Experimental Study of Horizontal-Longitudinal Coupling at CesrTA

lattice, cavity, simulation, scattering

1715

M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, S. Wang
CLASSE, Ithaca, New York, USA

Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505.
In storage rings, the presence of horizontal dispersion in the RF cavities introduces x-z coupling. The result is that the beam is skewed in the horizontal-longitudinal plane. The skew angle is proportional to the V15 term of the 6X6 coupling matrix which is proportional to the RF cavity voltage and the horizontal dispersion in the cavity. Here we report experiments at CesrTA where x-z coupling was explored using three distinct lattice configurations with different V15 coupling terms. We explore x-z coupling for each of these lattices by measuring the horizontal projection of the beam with a beam size monitor, as the RF voltage is varied. The first lattice has about 1 m dispersion in the RF cavities, resulting in a V15 term at the beam size monitor source point corresponding to 16 mrad x-z tilt. In the second, the V15 generated in one pair of cavities is compensated at the second pair by adjusting the horizontal betatron phase advance between the cavity pairs. In the third, the optics are adjusted so that the RF cavity region is dispersion-free, eliminating the coupling entirely. Additionally, intra-beam scattering is evident in our measurements of beam size vs. RF voltage.

TUPWA003

Beam Based Magnet Alignment for Emittance Coupling Minimization

sextupole, quadrupole, emittance, storage-ring

1724

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

Magnet misalignments give rise to field terms which can cause coupling between the horizontal and vertical beam motion and therefore emittance coupling. A series of beam based measurements have been developed at the Australian Synchrotron to accurately quantify quadrupole and sextupole alignments errors which cause coupling and where possible, correct them. Results showing an reduction in emittance coupling due to realignments of magnets based on these measurements will be presented. Limitations and general applicability of this method will also be discussed.

TUPWA014

The Status of Coupling Impedance Measurement for the CSNS/RCS Extraction Kicker Prototype*

impedance, kicker, simulation, extraction

1754

L. Huang, Y. Li, R.H. Liu, Y.D. Liu, S. Wang, O. Xiao
IHEP, Beijing, People's Republic of China

Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) is a high intensity proton accelerator, with average beam power of 100kW. In order to high intensity beam operation, the beam coupling impedance of the extracted kickers must be controlled. Longitudinal and transverse impedance of extracted kicker prototype with power supply had been roughly measured by coaxial-wire and dual-wire methods respectively. At the same time, impedance of window has been analyzed theoretically and simulated based on CST PARTICLE STUDIO.

TUPWA030

Impedances Calculations of Bellows in HLS II Storage Ring

impedance, wakefield, storage-ring, shielding

1784

Q. Zhang, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

The upgrade project of Hefei Lighe Source storage ring is carrying on.In this project,a new Bellows, in which shielding is provided by sprung fingers which can slide along the beam screen,is installed at the accelerator interaction area In order to reduce this impedance to an acceptable value. The contributions of Bellows to short range wakefields and broadband impedance were calculated numerically by Mafia code .

TUPWA050

Effect of Transverse Coupling on Asymmetric Cooling in Compton Rings

emittance, laser, electron, betatron

1823

E.V. Bulyak
NSC/KIPT, Kharkov, Ukraine
J. Urakawa
KEK, Ibaraki, Japan
F. Zimmermann
CERN, Geneva, Switzerland

Fast cooling of bunches circulating in a Compton ring is achieved by placing the collision point between electron bunches and laser pulses in a dispersive section and by, in addition, introducing a transverse offset between the laser pulse and the electron-beam closed orbit. Growth of the emittance in the dispersive transversal direction due to the additional excitation of betatron oscillations limits this type of cooling. Here we present the results of further studies on the fast cooling process, looking at the effect of the coupling of the transverse (betatron) oscillations. We first show theoretically that the transverse betatron coupling shortens the cooling time and hence reduces the steady-state energy spread of the electron beam, as well as the quantum losses. The theoretical estimates are then validated by simulations. Finally, a proof-of-principle experiment at the KEK ATF Damping Ring is proposed.

TUPWO001

A New 5BA Low Emittance Lattice for Sirius

emittance, lattice, dipole, sextupole

1874

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

Sirius is a third-generation low emittance synchrotron light source under construction at LNLS, the Brazilian Synchrotron Light Laboratory. A new 5BA lattice was designed in replacement for the previous TBA lattice with the aim to reduce the emittance to sub-nm.rad values. The new design has a circumference of 518 m with 20 achromatic straight sections and a natural emittance of 0.28 nm.rad at 3 GeV for the bare lattice (without IDs). The dipoles combine low 0.58 T field magnets for the main beam deflection with a 2 T short superbend magnet sandwiched in the center dipole. This creates a longitudinal dipole gradient that is used both to lower the emittance and to provide hard X-ray dipole sources.

TUPWO009

Decoupling Capabilities Study of the Emittance Transfer Section

emittance, solenoid, quadrupole, stripper

1895

C. Xiao, O.K. Kester
IAP, Frankfurt am Main, Germany
L. Groening, O.K. Kester, M.T. Maier
GSI, Darmstadt, Germany

Flat beams are those which feature unequal emittances in the horizontal and vertical phase space. The present paper is on the planning of the experimental proof of principle. Detailed simulations of the experiment, initially based on linear matrix transformations, are performed. The remarkable flexibility of the set-up w.r.t. to decoupling is addressed, as it can provide an one-knob tool to set the horizontal and vertical emittance partitioning. It was found that the decoupling capability of the set-up is remarkably flexible and the impact and discussion of this finding is treated in a dedicated section

TUPWO011

Invariant Criterion for the Design of Multiple Beam Profile Emittance and Twiss Parameters Measurement Sections

emittance, betatron, simulation, optics

1901

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

By studying errors in the reconstructed beam parameters as functions of the errors in the beam size measurements, we introduce an optimality criteria which can be used for the design and comparison of multiple beam profile emittance and Twiss parameters measurement sections and which is independent from the position of the reconstruction point.

TUPWO012

Relations Between Projected Emittances and Eigenemittances

emittance, beam-transport, electron, quadrupole

1904

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

We give necessary and sufficient conditions which two sets of positive real numbers must satisfy in order to be realizable as eigenemittances and projected emittances of a beam matrix. The information provided by these conditions sets limits on what one can to achieve when designing a beam line to perform advanced emittance manipulations (for example, round-to-flat beam transformations).

TUPWO017

Simulation on the Breaking of αx Multiknob Orthogonality in the Presence of Gradient and Coupling Errors and Experimental Investigation

simulation, quadrupole, sextupole, linear-collider

1919

S. Bai, J. Gao
IHEP, Beijing, People's Republic of China
P. Bambade
LAL, Orsay, France
G.R. White
SLAC, Menlo Park, California, USA

The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. In beam tuning towards the goal beam size, the presence of a tilt of the IP Shintake monitor fringe pattern with respect to the x-y coordinate system of the beam can break the orthogonality in the main σ34 and σ32 waist corrections required to reduce the vertical beam size at IP. Concerning the method of doing αx scan and measuring the vertical beam size to diagnose the IPBSM fringe tilt or residual σ13, one thing should be studied is to check what could break the orthogonality of the αx knob other than σ13 and the IPBSM fringe tilt. In this paper, we report on the simulation study that check for the breaking of orthogonality of the αx knob in the presence of gradient and coupling errors; to what extent this breaking of orthogonality can go; and also calculate the IPBSM fringe tilt angle from experiment results.

TUPWO047

Preliminary Results of Linear Optics From Orbit Response in the CERN PSB

quadrupole, dipole, optics, booster

1973

M.J. McAteer, C. Carli, B. Mikulec, R. Tomás
CERN, Geneva, Switzerland
M. Aiba
PSI, Villigen PSI, Switzerland

Funding: This research project is supported by a Marie Curie Early Initial Training Network Fellowship of the European Community's Seventh Framework Programme under contract number (PITN-GA-2011-289485-OPAC)
Future operations for the CERN accelerator complex will require the PS Booster to deliver higher intensity beam without increasing emittances, and having an accurate knowledge of the machine’s lattice imperfections will be necessary. We present preliminary results of the analysis of orbit response measurements in the PS Booster to determine the linear optics and to identify field errors in each of the machine’s four rings.

TUPWO048

Understanding the Tune, Coupling, and Chromaticity Dependence of the LHC on Landau Octupole Powering

closed-orbit, octupole, alignment, simulation

1976

E.H. Maclean, M. Giovannozzi, W. Herr, Y.I. Levinsen, G. Papotti, T. Persson, P.K. Skowroński, R. Tomás, J. Wenninger
CERN, Geneva, Switzerland

During the 2012 LHC run there were several observations of unexpectedly large shifts to the tune, chromaticity, and coupling which were correlated with changes in the powering of Landau octupoles (MO). Understanding the chromaticity dependence is of particular importance given it's influence on instabilities. This paper summarizes the observations and our attempts to-date to understand the relationship between Q, Q', c- and the MO powering.

TUPWO049

Automatic Correction of Betatron Coupling in the LHC using Injection Oscillations

injection, controls, quadrupole, betatron

1979

T. Persson, T. Bach, D. Jacquet, V. Kain, Y.I. Levinsen, E.H. Maclean, M.J. McAteer, P.K. Skowroński, R. Tomás, G. Vanbavinckhove
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

The control of the betatron coupling at injection and during the energy ramp is critical for the safe operation of the tune feedback and for the dynamic aperture. In the LHC every fill is preceded by the injection of a pilot bunch with low intensity. Using the injection oscillations from the pilot bunch we are able to measure the coupling at each individual BPM. The measurement is used to calculate a global coupling correction. The correction is based on the use of two orthogonal knobs which correct the real and imaginary part of the difference resonance term f1001, respectively. This method to correct the betatron coupling has been proven successful during the normal operation of the LHC. This paper presents the method used to calculate the corrections and its performance.

TUPWO064

Online Optimization Algorithms for Accelerators and Experimental Results

injection, optics, quadrupole, simulation

2012

X. Huang, W.J. Corbett, J.A. Safranek, J. Wu
SLAC, Menlo Park, California, USA

Online optimization of accelerators is becoming increasingly more important as accelerator systems become more and more complex. Online accelerator optimization is generally a multi-variant nonlinear problem with considerable noise. Efficiency and robustness are critical for online applications. Therefore optimization algorithms require special considerations. In this study we evaluate the viability of several online optimization algorithms for both ring and linac machines. Numerical simulations and experimental tests are presented to investigate performance of the algorithms.

WEPWO014

Rf Field-Attenuation Formulae for the Multilayer Coating Model

cavity, vacuum, electromagnetic-fields

2343

T. Kubo, T. Saeki
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan

Formulae that describe the RF electromagnetic field attenuation in the multilayer coating model with a single superconductor layer and a single insulator layer deposited on a bulk superconductor are derived with a rigorous calculation based on the Maxwell equations and the London equation.

WEPWO042

Dubna-Minsk SRF Technology Development Status Report

cavity, cryogenics, niobium, electron

2393

N.S. Azaryan, Ju. Boudagov, D.L. Demin, V.V. Glagolev, G. Shirkov, G.V. Trubnikov
JINR, Dubna, Moscow Region, Russia
M.A. Baturitsky, N.M. Shumeiko
NC PHEP BSU, Minsk, Belarus
S.E. Demyanov, E.Yu. Kaniukov
Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus, Minsk, Belarus
A. Ermakov, W. Singer, X. Singer
DESY, Hamburg, Germany
V.A. Karpovich, N.V. Liubetsky
BSU, Minsk, Belarus
S.V. Kolosov, A.A. Kurayev, A.O. Rak, A.K. Sinitsyn
Belarus State University of Informatics and Radioelectronics (BSUIR), Minsk, Belarus
S.I. Maximov, V.N. Rodionova
Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk, Belarus
A. Parshuto, V.S. Petrakovsky, I.L. Pobol, A.I. Pokrovsky, S.V. Yurevich, A.Yu. Zhuravsky
Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus

In 2011 Dubna-Minsk collaboration started an activity on the development and manufacture the series of 1.3 GHz superconducting Nb cavities in the enterprises in Belarus. The current status of this work is presented in this report. Main EM characteristics of the cavity were calculated and the shop drawings for cavity fabrication were developed. Two test-benches were assembled for RF-tests of the cavities at room temperature and at liquid helium temperature. The measured SWR was about 1.01 due to special matching device developed for that. This measurement technique was applied to the single-cell cavity from FNAL at power level nearby 10 mW. Measured resonant frequency was about 1.27 GHz, while the measured Q-factor was 2.8·10⁴ at room temperature and more than 10⁸ at liquid helium temperature. To evaluate mechanical properties of sheet Nb and of model materials (Cu and Al), a number of tests were made. Series of half-cells were fabricated of Al to test the technique of hydraulic deep-drawing that will be used in production of Nb cavities. The modes for electron-beam welding of sheet Nb were explored and the first welding seams were tested. The method of chemical treatment of cavities was also elaborated.

Poster WEPWO042 [0.897 MB]

WEPWO046

First Test Results of the 4-rod Crab Cavity

cavity, vacuum, niobium, pick-up

2405

R. Calaga, L.S. Alberty Vieira, S. Calatroni, O. Capatina, E. Ciapala, L.M.A. Ferreira, E. Jensen, P. Maesen, A. Mongelluzzo, T. Renaglia, M. Therasse
CERN, Geneva, Switzerland
P.K. Ambattu, D. Doherty, B.D.S. Hall, C. Lingwood
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
G. Burt
Lancaster University, Lancaster, United Kingdom

Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The first prototype crab cavity with the 4-rod geometry has undergone surface treatment and cold testing. Due to the complex geometry and unique fabrication procedure, RF validation of the field at beyond the nominal operating voltage at a sufficiently high Q0 is an important pre-requiste. Preliminary results of the first cold tests are presented along with cavity performance at different stages of the cavity processing is described.

WEPWO072

HOM Damping Coupler Design for the 400-MHz RF Dipole Compact Crab Cavity for the LHC HiLumi Upgrade

HOM, cavity, dipole, damping

2468

Z. Li, L. Ge
SLAC, Menlo Park, California, USA
S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA

Funding: Work partially supported by the US DOE through the US LHC Accelerator Research Program (LARP), and by US DOE under contract number DE-AC02-76SF00515.
Crab cavities are adapted as the baseline design for the LHC HiLumi upgrade to achieve head-on beam-beam collisions for further improvement in luminosity. A 400-MHz compact RF dipole crab cavity design was developed by a joint effort between Old Dominion University and SLAC under the support of US LARP program. This design has shown very favorable RF parameters and can fit into the available beamline spacing for either vertical and horizontal crabbing schemes. A niobium prototype cavity based on such a design has been manufactured for vertical test. In addition, there are stringent wakefield requirements that needed to be met for such a cavity in order to preserve the quality of the circulating beams. In this paper, we will discuss different damping schemes for such a compact design and present the HOM coupler designs to meet the damping requirements.

WEPWO073

RF Design Optimization for New Injector Cryounit at CEBAF

cavity, cryomodule, SRF, injection

2471

H. Wang, G. Cheng, F.E. Hannon, A.S. Hofler, R. Kazimi, J.P. Preble, R.A. Rimmer
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A new injector superconducting RF (SRF) cryounit with one new 2-cell, β=0.6 cavity plus one refurbished 7-cell, β=0.97, C100 style cavity has been re-designed and optimized for the engineering compatibility of existing module for CEBAF operation. The optimization of 2-cell cavity shape for longitudinal beam dynamic of acceleration from 200keV to 533keV and the minimization of transverse kick due to the waveguide couplers to less than 1 mrad have been considered. Operating at 1497MHz, two cavities has been designed into a same footprint of CEBAF original quarter cryomodule to deliver an injection beam energy of 5MeV in less than 0.27o rms bench length and a maximum energy spread of 5keV.

WEPWO084

Improvement of the Q-factor Measurement in RF Cavities

cavity, dipole, pick-up, HOM

2489

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi
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.
The Q values of Higher-order-modes (HOMs) in RF cavities are measured at room temperature with the 3 dB bandwidth reading by a network analyzer. The resonant curve distortion is created by the resonance splitting due to the ellipticity caused by manufacture tolerance and RF ports. Therefore, the measured Q values are usually lower than the simulated or theoretical Q values. In some cases, even only one mode’s Q can be measured with the 3 dB method. There may be two reasons for this happening. One is that only one mode was excited and the neighbor splitmode was close to 90° polarized; the other reason is that the resonant curve of one mode was distorted by the other mode too much to measure the 3dB range. In this paper, we resolve this issue by looking into the RF measurement setup, including cavity, input coupler and pick-up coupler, from the equivalent circuit and wave point of view. Based on the BNL3 copper prototype cavity, we compared these results from measurement and simulation.

WEPEA064

SixTrack-Fluka Active Coupling for the Upgrade of the SPS Scrapers

simulation, injection, luminosity, synchrotron

2657

A. Mereghetti, F. Cerutti, R. De Maria, B. Goddard, V. Kain, M. Meddahi, O. Mete, Y. Papaphilippou, D. Pastor Sinuela, V. Vlachoudis
CERN, Geneva, Switzerland
R. Appleby
UMAN, Manchester, United Kingdom

The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Essential for the clean injection into the LHC, the SPS scrapers are one of the important systems under revision. In order to take into account of the effect of betatron and longitudinal beam dynamics on energy deposition patterns, and nuclear and Coulomb scattering in the absorbing medium onto loss patterns, the SixTrack and Fluka codes have been coupled, profiting from the best of the refined physical models they respectively embed. The coupling envisages an active exchange of tracked particles between the two codes at each turn, and an on-line aperture check in SixTrack, in order to estimate the local cleaning inefficiency of the system. Knob-like, time-dependent strengths have been implemented in SixTrack, since the designed scraper system foresees the use of a magnetic bump. The study is intended to assess the robustness of the proposed scraper as well as its effectiveness with respect to the desired performance.

WEPFI014

Present Status and Progresses of RFQ of IFMIF/EVEDA

rfq, vacuum, linac, quadrupole

2729

R. Dima, A. Pepato, F. Scantamburlo, E. Udup
INFN- Sez. di Padova, Padova, Italy
F. Grespan, A. Palmieri, C. Roncolato
INFN/LNL, Legnaro (PD), Italy

The RFQ of IFMIF/EVEDA is designed to accelerate a 125 mA D⁺ beam from 0.1 MeV to 5 MeV at a frequency of 175 MHz. The production of the modules 16, 17 and 18 necessary has been completed. In this paper the progress and improvements on the production of the modules, as well the development of the brazing procedure design will be described.

WEPFI018

Comparison of High Gradient Performance in Varying Cavity Geometries

damping, vacuum, acceleration, HOM

2741

T. Higo, T. Abe, Y. Arakida, Y. Higashi, S. Matsumoto, T. Shidara, T. Takatomi, M. Yamanaka
KEK, Ibaraki, Japan
A. Grudiev, G. Riddone, W. Wuensch
CERN, Geneva, Switzerland

Four types of CLIC prototype TW accelerator structures were high-gradient tested at Nextef, KEK, up to 100 MV/m level and the fifth is under test now. The ramping speed of each processing and the resultant breakdown rate were compared among them. From this comparison, it was found that the ramping speed of the structures with opening ports for HOM damping with magnetic coupling became slow and the resultant breakdown rate became high. It was also found that that with lower surface magnetic field showed faster ramping in processing and lower breakdown rate. This indicates the role of the magnetic field on vacuum breakdowns in copper structure at the region of several tens to 100 MV/m. In this paper, we review the processing stage and the high gradient performance of these structures trying to discuss the relevant parameters, surface electric field, surface magnetic field and other parameters such as Sc, “complex pointing vector”, to the performance difference.

WEPFI040

R&D of C-band Pulse Compression for Soft X-ray FEL at SINAP

cavity, simulation, FEL, klystron

2791

C.P. Wang, W. Fang, Q. Gu, W.C. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A compact Soft X-ray Free Electron Lasers facility is presently being constructed at SINAP, and 8 C-band accelerating structure unit are required for third-stage including 4 pulse compressors. The field mode of C-band SLED is TE0.1.15 with high quality factor Q, and the coupling coefficient is 8.5. Based on the design, the power pulse of klystron is compressed from 2.5μs to 0.5μs, and finally the power gain is about 3.1. In this paper, the details and simulation of 3-dB coupler, mode convertors and the resonant cavities are presented, meanwhile some cold test results of cavity are also analyzed at the end of this paper.

WEPFI044

High Power Test of New SLED System with Biplanar 3-dB Power Divider and Dual Side-wall Coupling Irises for PAL XFEL

klystron, simulation, cavity, free-electron-laser

2803

Y.D. Joo, H. Heo, W.H. Hwang, H.-S. Lee, K.M. Oh, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

The new type of the Stanford Linear Accelerator Energy Doubler (SLED) system for the PAL (Pohang Accelerator Laboratory) XFEL (X-ray Free Electron Laser) is developed to be operated with an RF input power of 80 MW and a pulse width of 4 μs. To prevent the RF breakdown such a high power operation, a biplanar 3-dB power divider and dual side-wall coupling irises structure are used in the new SELD system. It is shown that the field gradient and surface current is reduced from that of the original SLED system using the the finite-difference time-domain (FDTD) simulation. The high power test result of the new SLED system in the PAL XFEL test facility will be presented.

WEPFI058

Breakdown Localization Studies on the SwissFEL C-band Test Structures

background, linac, factory, impedance

2824

J. Klavins, S. Dementjevs, F. Le Pimpec, L. Stingelin, M. Wohlmuther, R. Zennaro
PSI, Villigen PSI, Switzerland
N.C. Shipman
CERN, Geneva, Switzerland

The SwissFEL main linac will consist of 10⁴ C-band structures with a nominal accelerating gradient of 28MV/m. First power tests were performed on short constant impedance test-structures composed of eleven double-rounded cups. In order to localize breakdowns, two or three acoustic emission sensors were installed on the test-structures. In order to localize breakdowns we have analyzed, in addition to acoustic measurements, the delay and phase of the rf power signals. Parasitic, acoustic noise emitted from the loads of the structure complicated the data interpretation and necessitated appropriate processing of the acoustic signals. The Goals of the experiments were to identify design and manufacturing errors of the structures. The results indicate that breakdowns occur mostly at the input power coupler, as also confirmed by vacuum-events at the same location. The experiments show that the linac test-structures fulfill the requirements in breakdown probability. Moreover developing a detection system based on acoustic emission sensors for breakdown localization for our C-band structure seems reasonable given the results obtained.

WEPFI059

C-band RF Pulse Compressor for SwissFEL

resonance, HOM, cavity, klystron

2827

R. Zennaro, M. Bopp, A. Citterio, R. Reiser, T. Stapf
PSI, Villigen PSI, Switzerland

The SwissFEL C-band (5.712 GHz) linac consists of 28 RF modules. Each module is composed of a single 50 MW klystron feeding a pulse compressor and four two meter long accelerating structures. The pulse compressor is based on a single Barrel Open Cavity (BOC). The BOC makes use of a “whispering gallery” mode which has an intrinsically high quality factor and operates in resonant rotating wave regime; moreover, and contrary to the conventional SLED scheme, a single cavity is sufficient to define the pulse compressor, without the need for two cavities and a 3-dB hybrid. A prototype has been manufactured and successfully tested. A short description of the BOC is presented, together with the prototype design, production, low level RF measurements, and high power test.

WEPFI060

Planar Balun Design with Advanced Heat Dissipation Structure for kW Level Solid-state Amplifier Module Development

controls, impedance, storage-ring, klystron

2830

T.-C. Yu, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, Z.L. Liu, C.H. Lo, M.H. Tsai, Ch. Wang, T.-T. Yang, M.-S. Yeh
NSRRC, Hsinchu, Taiwan

The power level of solid-state amplifier is continuously growing for advanced accelerator application as the RF power source. Huge amount of solid-state power amplifier (SSPA) modules can contribute several hundreds of kW RF power with high redundancy and reliability. However, with the increasing desire of RF power of single RF station, too much power modules would adversely cause larger area occupation and higher maintenance cost and complexity. Therefore, with the advancement of the RF power on single SSPA, the overall system design and configuration would become much simple and compact. However, the increasing RF of single SSPA would also bring the thermal problem at its chip as well as the output power combining balun. In this paper, kW range SSPA is developed with the novel planar balun structure with good thermal expansion property. With such new planar balun design, the SSPA can operate stably with above 1kW output RF power.

WEPFI061

Petra Cavity Vacuum RF Condition with Field Balance Mechanism for TPS Storage Ring in NSRRC

cavity, vacuum, controls, storage-ring

2833

T.-C. Yu, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, Z.L. Liu, C.H. Lo, M.H. Tsai, Ch. Wang, T.-T. Yang, M.-S. Yeh
NSRRC, Hsinchu, Taiwan

In the first stage commissioning of TPS (Taiwan Photon source) storage ring in NSRRC, two room temperature Petra cavities will be used. At this commission stage, 100mA with 950keV beam loss is estimated to have 47.5kW beam loss for each cavity. In the meanwhile, the cavity loss at the specified 1.2MV of each cavity will be about 50kW. Therefore, coupling coefficient of 2 is required. However, the initial design specification of Petra cavity has only beta of about 1.7. Hence, the modification of the input coupler is done with the enhancement of its beta as well as advanced water cooling for some heat point. Besides, due to the two-tuner system of Petra cavity, special field-balance tuner control system is also developed. In RF condition for better vacuum up to 1.4MV, some modification of the tuner mechanical structure is also done to reach high vacuum condition (lower than 5*10^-9 Torr) for storage ring requirement.

WEPFI070

Design of RFQ Coupler for PXIE Project

rfq, simulation, cavity, ion

2854

S. Kazakov, T.N. Khabiboulline, V. Poloubotko, O. Pronitchev, V.P. Yakovlev
Fermilab, Batavia, USA

Design of new coupler for PXIE RFQ is reported. Two couplers are supposed to deliver ~ 100 kW total CW RF power to RFQ at 162.5 MHz. Coupler has a magnetic loop coupling with the RFQ. Nevertheless it allows to apply a HV bias to suppress a multipactor due to original design of the coupling loop. Results of RF, multipactor and thermal simulations are presented.

WEPFI073

A Modular Cavity for Muon Ionization Cooling R&D

cavity, simulation, vacuum, solenoid

2860

D.L. Bowring, A.J. DeMello, A.R. Lambert, D. Li, S.P. Virostek, M.S. Zisman
LBNL, Berkeley, California, USA
C. Adolphsen, L. Ge, A.A. Haase, K.H. Lee, Z. Li, D.W. Martin
SLAC, Menlo Park, California, USA
D.M. Kaplan
Illinois Institute of Technology, Chicago, Illinois, USA
T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
A. Moretti, M.A. Palmer, R.J. Pasquinelli, Y. Torun
Fermilab, Batavia, USA
R.B. Palmer
BNL, Upton, Long Island, New York, USA

The Muon Accelerator Program (MAP) collaboration is developing an ionization cooling channel for muon beams. 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 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 based on a modular pillbox cavity operating at 805 MHz. The modular cavity design allows for the evaluation of different cavity materials - such as beryllium - which may ameliorate or circumvent RF breakdown triggers. Modular cavity components may furthermore be prepared with different surface treatments, such as high-temperature baking or chemical polishing. This poster presents the design and experimental status of the modular cavity, as well as future plans for the experimental program.

WEPFI079

Electromagnetic Modeling of RF Drive in the LANSCE DTL

cavity, DTL, simulation, HOM

2878

S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

A 3D electromagnetic model of the RF drive module in the LANSCE DTL tank 4 has been developed with the CST MicroWave Studio. The model is explored both with eigensolver and in time domain to evaluate maximal fields in the drive module and RF coupling. Here we describe the model and present simulation results.

WEPFI080

Waveguide Component R&D for the ILC

klystron, linac, cavity, linear-collider

2881

C.D. Nantista, C. Adolphsen, G.B. Bowden, A.A. Haase, B.D. McKee, F.Y. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
Several years of effort have gone into refining the design of the International Linear Collider. The direction the design has evolved in response to driving considerations has resulted in a more sophisticated waveguide system for delivering RF power to the cavities. In particular, the desire to eliminate parallel service tunnels along the main linacs led to the proposal of the Klystron Cluster Scheme (KCS)*, involving plumbing the combined power from groups of klystrons down from the surface at several locations in overmoded waveguide. Additionally, to increase superconducting cavity yield, the acceptance criteria were relaxed to encompass a ±20% range in sustainable operating gradient, which must be accommodated by tailoring of the RF power distribution. Designs and prototype testing of some of the novel waveguide components developed to allow these changes are described here.
* Christopher Nantista and Chris Adolphsen, “Klystron Cluster Scheme for ILC High Power RF Distribution,” presented at the 2009 Particle Accel. Conf., Vancouver, B.C., Canada, May 2009.

WEPFI081

High Power Tests of Overmoded Waveguide for the ILC Klystron Cluster Scheme

resonance, klystron, linac, simulation

2884

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

A Klystron Cluster Scheme has been proposed for the ILC Main Linacs in which the output power of up to thirty, 10 MW, 1.3 GHz klystrons are combined in a single, 0.5 m diameter circular waveguide in a surface building and transported down to and along the accelerator tunnel where it is periodically tapped-off to power strings of cavities. This schemes eliminates the need for a separate linac service tunnel and simplifies the linac electric and cooling distribution systems. Recently, a 40 meter long circular waveguide with a coaxial input coupler and a 90 degree rf bend were assembled and run in a resonant configuration to test the concept. With the pipe pressurized with up to 30 psig of N2 to raise the rf breakdown threshold, it was demonstrated that field levels equal to those for the 300 MW transmission required for ILC could be sustained reliably. We report on these and other test results from this program.

WEPFI088

High-power Tests of an Ultra-high Gradient Compact S-band (HGS) Accelerating Structure

vacuum, klystron, monitoring, linac

2902

L. Faillace, R.B. Agustsson, P. Frigola, A.Y. Murokh, S. Seung
RadiaBeam, Santa Monica, USA
S.G. Anderson
LLNL, Livermore, California, USA
V.A. Dolgashev
SLAC, Menlo Park, California, USA
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
V. Yakimenko
BNL, Upton, Long Island, New York, USA

RadiaBeam Technologies reports on the RF design, fabrication and high-power tests of a ultra-high gradient S-Band accelerating structure (HGS) operating in the pi-mode at 2.856 GHz. The compact HGS structure offers a drop-in replacement for conventional S-Band linacs in research and industrial applications such as drivers for compact light sources, medical and security systems. The electromagnetic design (optimization of the cell shape in order to maximize RF efficiency and minimize surface fields at very high accelerating gradients) has been carried out with the codes HFSS and SuperFish while the thermal analysis has been performed by using the code ANSYS. The high-power conditioning was carried out at Lawrence Livermore National Laboratory (LLNL).

WEPFI089

High Gradient Normal Conducting Radio-frequency Photoinjector System for Sincrotrone Trieste

gun, cathode, quadrupole, dipole

2905

L. Faillace, R.B. Agustsson, H. Badakov, P. Frigola
RadiaBeam, Santa Monica, USA
F. Cianciosi, P. Craievich, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Fukasawa, J.B. Rosenzweig, A. Yakub
UCLA, Los Angeles, California, USA

Radiabeam Technologies, in collaboration with UCLA, presents the development of a high gradient normal conducting radio frequency (NCRF) 1.6 cell photoinjector system for the Sincrotrone Trieste facility. Designed to operate with a 120MV/m accelerating gradient, this single feed, fat lipped racetrack coupler design is modeled after the LCLS photoinjector with a novel demountable cathode which permits cost effective cathode exchange. Full overview of the project to date and installation at Sincrotrone Trieste will be discussed along with basic, design, engineering and manufacturing.

WEPFI092

Multipacting Simulation of the MICE 201 MHz RF Cavity

cavity, solenoid, electron, simulation

2914

T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
D.L. Bowring, A.J. DeMello, D. Li, P. Pan, S.P. Virostek
LBNL, Berkeley, California, USA
L. Ge
SLAC, Menlo Park, California, USA

The international Muon Ionization Cooling Experiment (MICE) aims to demonstrate transverse cooling of muon beams by ionization. The MICE ionization cooling channel requires eight 201-MHz normal conducting RF cavities to compensate for the longitudinal beam energy loss in the cooling channel. Multipacting is a resonant electron discharge produced by the synchronization of emitted electrons with the RF fields, which can cause breakdown at high power RF operation. In this paper, we present the study of the multipacting effect in the MICE 201 MHz cavities with the SLAC ACE3P code. The simulation is carried out in the cavity body, the RF coupler region, and the coaxial waveguide, with the external magnetic field from the Coupling Coil. We will identify potential RF breakdowns due to multipacting and propose a solution to suppress them.

WEPME001

SOLEIL Beam Stability Status

feedback, emittance, undulator, electron

2917

N. Hubert, L. Cassinari, J.-C. Denard, M. Labat, J.-F. Lamarre, A. Nadji, L.S. Nadolski, D. Pédeau, M.-A. Tordeux
SOLEIL, Gif-sur-Yvette, France

This paper reports recent work for improving SOLEIL electron beam stability. X-BPMs from four bending magnet beamline frontends have been inserted in the global orbit feedback loops during user operation. The corresponding source point stabilities have improved and results are reported. Some of the new beamlines request more stringent stability than the existing ones. Their requirements are not only tighter for beam orbit but also for beam size and divergence stability. For these reasons, SOLEIL has decided to define beam quality criteria for each sensitive beamline. Then it can predict ahead of commissioning how well the beamline will likely perform. A feedback on the vertical emittance, measured by a pinhole camera, has been introduced in order to reduce beam size and divergence variations due to magnetic configuration changes of a few insertion devices.

WEPME015

Evaluation of the Superconducting LLRF system at cERL in KEK

LLRF, cavity, controls, linac

2956

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

A low level RF (LLRF) design is being currently developed within the compact Energy Recover Linac (cERL) at KEK. One challenging task is to achieve the high amplitude and high phase stability required by the accelerating fields of up to 0.1% and 0.1°, respectively. To improve the performance of the LLRF system, a gain scanning experiment for determining the optimal controller gain was carried out on the cERL. Furthermore, as a substitute for the traditional PI controller, a more robust H∞-based multiple input multiple output (MIMO) controller was realized. This controller requires more detailed system information (transfer function or state equation), which can be acquired by using modern system identification methods. In this paper, we describe the current status of these experiments on the cERL.

WEPME058

Integrated System Modeling Analysis of a Multi-cell Deflecting-mode Cavity in Cryogenic Operation

cavity, simulation, cryomodule, vacuum

3064

Y.-M. Shin, M.D. Church, J. Ruan
Fermilab, Batavia, USA

Over the past decade, multi-cell deflecting (TM110) mode cavities have been employed for experiments on six-dimensional phase-space beam manipulation *,**,***,****,****** at the A0 Photo-Injector Lab (16 MeV) in Fermilab and their extended applications with vacuum cryomodules are currently scheduled at the Advanced Superconducting Test Accelerator (ASTA) user facility (> 50 MeV). Despite the successful test results, the cavity, however, demonstrated limited RF performance during liquid nitrogen (LN2) ambient operation that was inferior to theoretic prediction. We thus fully inspected the cavity design with theoretical calculation (based on Panofsky-Wenzel theorem) combined with RF simulations. Also, we are extensively developing an integrated computational tool with comprehensive system analysis capacity to solve complex thermodynamics and mechanical stresses of a high-Q deflecting-mode cryomodule. We will benchmark simulation analysis result with experimental data from high power RF tests in Fermilab. Successfully developed modeling tool will be potentially used for prompt assessment on RF performance of vacuum-cryomodules.
* D. A. Edwards, LINAC 2002
** Y.-E Sun, PRTAB 2004
*** P. Piot, PRSTAB2006
**** J. Ruand et al., PRL 2011
***** Y.-E. Sun, et al., PRL 2010

WEPME061

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

kicker, impedance, feedback, simulation

3073

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

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP) and by the EU FP7 HiLumi LHC - Grant Agreement 284404.
Control and mitigation of transverse beam instabilities caused by electron cloud and TMCI will be essential for the SPS to meet the beam intensity demands for the HL-LHC upgrade. A wideband intra-bunch feedback method is in development, based on a 4 GS/s data acquisition and processing, and with a back end frequency structure extending to 1 GHz. A slotted type kicker, similar to those used for stochastic cooling, has been considered as the terminal element of the feedback chain. It offers the most promising deflecting structure characteristics to meet the system requirements in terms of bandwidth, shunt impedance, and beam coupling impedance. Different types of slotted structures have been explored and simulated, including a ridged waveguide and coaxial type waveguide. In this paper we present our findings and the conceptual design of a vertical SPS wideband kicker consistent with the stay clear, vacuum, frequency band coverage, and peak shunt impedance requirements.

THPEA043

An Equipment Hub for Managing a Small Town and a Complex Machine

radiation, controls, status, collider

3237

P. Martel, A. Alexandre Metola, Ch. Delamare, M.P. Kepinski, S. Mallon Amerigo, L. Pater, S. Petit, D. Widegren
CERN, Geneva, Switzerland

Effective maintenance of the accelerators’ complex is vital for CERN’s mission. While this work is highly dependent on operational planning and constraints, it also needs to be coordinated with the maintenance of the infrastructure where the complex is embedded. The nature and degree of the logistics problems that arise from this interdependence cannot be handled by partial, decoupled solutions from each of the stakeholders. CERN’s Enterprise Asset Management system is the central hub where all relevant data about equipment and its maintenance is kept. It is also where data and documents about the manufacturing, installation, safety inspection, radiation measurements, disposal, etc. of the scientific equipment reside. This hub allows the effective sharing of consistent equipment data, accessed by a large number of people and systems, and supplies a wide range of interfaces – ranging from the user in the field with no access to a desktop computer, to scheduling systems that need to interact with it through Web services; this is achieved by means of a series of systems, tools and mechanisms, all dedicated to different needs but working on the same data and sharing common policies.

THPFI014

Bellows with a New RF Shield Made of Metal Braid for High Intensity Proton Accelerators

impedance, vacuum, background, synchrotron

3321

N. Ogiwara, J. Kamiya, M. Kinsho, Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
O. Koizumi
Sun-Tech limited, Kobe, Japan

In the 3 GeV-RCS (Rapid cycling Synchrotron) in J-PARC (Japan Accelerator Research Complex) project, large-scale hydro-formed bellows were developed to adjust the gap between the ceramic ducts and/or between the ceramic ducts and the transport ducts. They have been equipped with a newly developed RF shield, because the usual beryllium-copper spring finger contacts were found to be very hard (roughly 1000 N/mm) owing to the large size. This contact is made of Ti braid, which consists of wires with a diameter of 0.3 mm. This RF contact is a kind of basket (with two ports) made with the braids. Because of the spring effect, the contact can change shape easily. In addition, the contact can easily connect the different cross sections in a smooth fashion. Furthermore, this structure is almost free from the dust generation, which is one of the most troublesome problems for the usual spring finger contacts. This time, we have constructed reserve bellows with the RF shield made of SUS 316L wires to improve the reliability of user operation. The outline of the bellows will be presented, especially laying emphasis on the mechanical function of the RF shield.

THPFI023

A Newly Developed High Directivity X-band Waveguide Directional Coupler

simulation, insertion, pick-up, vacuum

3345

X. He, X. Wang, F. Zhao
IHEP, Beijing, People's Republic of China

A new X-band waveguide directional coupler working at 11.9924 GHZ is designed. Four holes symmetrical to the structure is drilled along the central line of the narrow-wall, which is used to couple the electromagnetic power from the main-waveguide to the sub-waveguide. The final prototype has got a measurement result of 32.2 dB Directivity (-47.0 dB Coupling Degree) together with a very low VSWR (1.067) and Insertion Loss (-0.11 dB) at 11.9924 GHz. The vacuum performance is also qualified.

THPFI051

Radio-Frequency Multipacting as Quality Control of Coatings for e-Cloud Suppression

dipole, electron, resonance, vacuum

3403

P. Costa Pinto, J. Bauche, S. Calatroni, F. Caspers, P. Edwards, M. Holz, M. Taborelli
CERN, Geneva, Switzerland

To mitigate electron clouds in particle accelerators, a carbon coating with low SEY has been developed. In the case of the SPS (Super Proton Synchrotron), which belongs to the LHC injector chain, testing the performance of coated beam pipes directly in the accelerator must cope with the schedule of the regular machine operation. For this reason an alternative instrument based on RF induced multipacting in a coaxial configuration has been designed for ex-situ characterization of the main bending dipoles of the SPS. In this contribution we report the results obtained before and after coating for two 6.4 meter dipoles with different cross sections of the vacuum chambers. The multipacting is monitored by measuring the pressure rise and the RF reflected power. After coating, the power threshold to induce multipacting is strongly reduced indicating a lower propensity for electron cloud. The impact of the RF coupling on the sensitivity of the technique is discussed.

THPFI057

Development of Vacuum Chamber in Low Z Material

vacuum, radiation, impedance, background

3421

C. Garion, P. Costa Pinto, M.A. Gallilee, J. Perez Espinos
CERN, Geneva, Switzerland

Highly transparent vacuum chambers are more and more required in high energy particle physics. In particular, vacuum chambers in the experiments should be as transparent as possible to minimize the background to the detectors while reducing also the material activation. Beryllium is, so far, the most performing material for this application, but it presents some drawbacks such as brittleness, manufacturing issues, toxic hazard, high cost and low availability. A development work to obtain alternative material to the beryllium with similar performance is being carried out at CERN. Three categories have been defined and considered: raw bulk material, material and structural composites. Main requirements are the vacuum compatibility: leak tightness, low outgassing rate, temperature resistance (in the range 200-230 °C), transparency, and mechanical stiffness and strength. Carbon is the element with the lowest atomic number after beryllium and that is appropriate for this application. Therefore carbon based materials have been considered in a variety of options. In this paper, several technologies are presented and discussed. Results of preliminary tests on samples are also shown.

THPME048

Assembly and Test of a Modified Spectrometer Solenoid for MICE

solenoid, radiation, target, controls

3621

S.P. Virostek, D. Li, P. Pan, S. Prestemon
LBNL, Berkeley, California, USA
R. Preece
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

Funding: This work is supported by the Office of Science, US-DOE under DOE contract DE-AC02-05CH11231.
The MICE superconducting spectrometer solenoids have been modified and rebuilt as a result of the testing done in 2008, 2009 and 2010. The number of two-stage cryocoolers was increased from three in 2009 to five in the modified magnet. The new shield for the spectrometer solenoid is fabricated primarily from 1100-O aluminum instead of 6061-T6 aluminum used in the former versions of the magnet. The thermal connection between the shield and the first-stage of the cold heads has been improved to reduce the temperature drop between the shield and the coolers. As a result of these changes, the first-stage temperatures for the coolers are below 45K, which resulted in an increase in the refrigeration generated by the cooler second stages. The quench protection system has been altered in order to provide additional protection to the magnet in the event of a lead failure between the magnet power supply and the magnet coils. The quality of the shield and cold mass MLI wrap has also been improved. Details of the modifications and test results demonstrating improved magnet performance are presented in this paper.

THPWA018

High Power Test of a C-band 6 MeV Standing-wave Linear Accelerator

target, radiation, brightness, gun

3666

J.H. Shao, H.B. Chen, Y.-C. Du, Q.X. Jin, J. Shi, H. Zha
TUB, Beijing, People's Republic of China

A C-band 6MeV standing-wave bi-periodic on-axis coupled linear accelerator has been developed at the accelerator laboratory of Tsinghua University [1,2]. In the recent high power RF test, the capture ratio, the energy spectrum, the spot size and the dose rate of this accelerator have been measured. With a 2.07-MW input power, the peak current is 130mA and the output spot root-mean-square diameter is about 0.8mm. The output kinetic energy is 6.0MeV with a spectrum FWHM of 7.5%. In this paper, the setup and detailed results of the high power RF test are presented.

THPWA030

Design and Prototype Test of C-band Standing-wave Accelerating Structure to Enhance RF Phase Focusing

electron, focusing, bunching, simulation

3690

H. Yang, M.-H. Cho, W. Namkung, S.-G. Shin
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.H. Kim
ANL, Argonne, USA
J.-S. Oh
NFRI, Daejon, Republic of Korea

Funding: This research was financially supported by the MOTIV, KIAT and Dongnam Institute for Regional Program Evaluation through the Leading Industry Development for Economic Region
A C-band standing-wave accelerator for X-ray and electron beam sources of medical radiotherapy is designed and being fabricated. The accelerator system is to be operated in two modes, using the X-ray and electron beams. Because of the energy loss in electron mode, the accelerator is capable of producing 6-MeV, 100-mA electron beams with peak 2-MW RF power, and 7.5-MeV, 20 mA electron beams with peak 2.5-MW RF power. The beam radius at the end of column was < 0.5 mm without focusing magnets in PARMELA simulations, because the bunching cells are designed to enhance the RF phase focusing. Each cavity in the bunching and normal cells was designed by the MWS code to maximize the effective shunt impedance with 3.8% inter-cell coupling in normal cells. The dimensions of normal cells were determined by the low power RF test of prototype cells with 5711.06-MHz resonant frequency and 3.5% inter-cell coupling. In this paper, we present details of the accelerator design and prototype test.

THPWO004

RF Tuning of the LINAC4 RFQ

rfq, linac, quadrupole, dipole

3761

O. Piquet, Y. Le Noa, J. Novo
CEA/DSM/IRFU, France
M. Desmons, A. France
CEA/IRFU, Gif-sur-Yvette, France
C. Rossi
CERN, Geneva, Switzerland

The construction of Linac4, the new 160 MeV CERN H⁻ injector, has started with the goal of improving the LHC injection chain with a new higher energy linac. The low energy front end of Linac4 is based on a 352 MHz, 3-m long Radiofrequency Quadrupole (RFQ) which accelerates the 70 mA, 45 keV H⁻ beam from the ion source to the energy of 3 MeV. The RFQ, made of three modules, one meter each, is of the four-vane type and it has been designed in collaboration between CERN and CEA. Construction has started in 2009 and all the steps of machining and assembly have been done at CERN. The RFQ is equipped with 35 fixed tuners and one waveguide RF port located in the second module. This paper describes the procedure used to tune the accelerating field and the power coupler of the LINAC4 RFQ in order to achieve the nominal voltage profile within ±1% accuracy.

THPWO015

First Coupled CH Power Cavity for the FAIR Proton Injector

cavity, linac, proton, alignment

3791

R. M. Brodhage, U. Ratzinger
IAP, Frankfurt am Main, Germany
G. Clemente, W. Vinzenz
GSI, Darmstadt, 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 Summer 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. Before Spring 2013 the final drift tube structure will be welded inside the main tanks and the preparation for copper plating will take 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.

THPWO041

The development of a high power input coupler for China ADS injector I RFQ

rfq, cavity, vacuum, injection

3857

T.M. Huang, X. Chen, R. Guo, H.Y. Lin, Q. Ma, F. Meng, H.F. Ouyang, W.M. Pan, X.H. Peng, Z. Zhang, G.Y. Zhao
IHEP, Beijing, People's Republic of China

A 325 MHz RFQ is designed to accelerate a beam current of 15 mA in CW mode with injection energy of 35 keV and output energy of 3.2 MeV for China Accelerator Driven sub-critical System (ADS) injector I. Total RF power of 320 kW has to be delivered into the RFQ cavity. For reliable operation, four input couplers are adopted to share the driven power. A coaxial loop type input coupler is developed. The coupler features a Tristan type RF window, a doorknob to realize the transition from a half-height WR2300 waveguide to a coaxial line and a coaxial line with a coupling antenna loop. Two prototypes of the window and inner conductor assemblies have been fabricated and received high power test. The prototypes were tested up to 100 kW CW RF power in traveling wave mode. This paper will describe the design, fabrication and high power test of the coupler in details.

FRXAA01

Beam Dynamics and Collective Effects in "Ultimate" Storage Rings

emittance, ion, electron, scattering

3981

M. Takao
JASRI/SPring-8, Hyogo-ken, Japan

This presentation will review the beam dynamics issues such as impedance driven instabilities, intrabeam scattering, and the Touschek lifetime in ultimate storage rings with very low emittance.

Slides FRXAA01 [11.245 MB]