IPAC2013 - List of Keywords (resonance)

Paper	Title	Other Keywords	Page
MOPEA067	Ultra-low Emittance Upgrade Options for Third Generation Light Sources	emittance, lattice, dipole, dynamic-aperture	237
	R. Bartolini Diamond, Oxfordshire, United Kingdom T. Pulampong JAI, Oxford, United Kingdom
	The increasing efforts in the synchrotron light sources community toward the design of a diffraction limited source at multi-keV photon energy have eventually stimulated the existing facilities to investigate possible upgrade paths to higher photon brightness and lower emittances to maintain their competitiveness within the users’ community. We present a possible option for upgrading 3rd generation light sources based on a rebiuld of the arcs with MBA cells, using diamond as an example. Emphasis is given to the AP desing issues with a view to minimal changes to the machine layout, contained cost and minimal downtime

MOPFI007	SIS-18 RF Knock-Out Optimization Studies	extraction, dipole, septum, synchrotron	297
	M.M. Kirk, D. Ondreka, P.J. Spiller GSI, Darmstadt, Germany
	The extraction efficiency and spill temporal-structure of the SIS-18 heavy ion synchrotron are part of the upgrades to the GSI accelerator complex. Losses to the extraction septum can be minimised through implementation of the Hardt condition resulting however in a poorer quality of the spill microstructure at resolutions of a few microseconds due to lowering of the horizontal chromaticity from its 'natural' value. Ways to improve the extraction efficiency and spill microstructure are investigated with a tracking code. One possibility for improvement may be to use an alternative RF modulation applied to the knock-out exciter.

MOPFI020	Cold Test of the Coaxial Cavity for Thermionic Triode Type RF Gun	cavity, gun, electron, FEL	324
	T. Konstantin, Y.W. Choi, T. Kii, R. Kinjo, K. Masuda, M. Mishima, K. Nagasaki, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, K. Yoshida, H. Zen Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	A thermionic rf gun has several advantages as compared to photocathode gun. Such as low cost, high averaged current and simple operation. However a thermionic rf gun has a significant disadvantage in form of back bombardment effect. The KU-FEL facility is an oscillator type FEL, which uses a thermionic 4.5 cell S-band RF gun for electron beam generation. The back bombardment effect causes increasing current in macropulse, which limits the gain of the FEL. In order to mitigate the current increase we plan to modify thermionic rf gun to triode type rf gun. Therefore an additional rf cavity has been designed. This cavity has separate rf power supply with amplitude and phase control. By this means we can properly adjust the injection of electrons into the main gun body. According to simulations the triode type gun can reduce 80% of back streaming electron energy. The cold tests of the first prototype have revealed deviation from designed values. Based on the tests of the first prototype new prototype with integrated mechanism for resonance tuning has been designed and fabricated. In this work we report the cold test of the redesigned prototype of the coaxial rf cavity. K. Masuda et al. Proceedings of FEL 2006, BESSY Berlin. ** M. Takasaki et al. Proceedings of FEL 2010, Malbö

MOPFI045	Studying of Multipacting in Micro-pulse Electron Gun	electron, gun, simulation, cavity	383
	L. Liao, W. Fang, Q. Gu, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	Depending on the complexity of multipacting phenomenon, more works are focused on the occurrence of multipacting in the micro-pulse electron gun. In this paper, the multipacting resonance condition is determined in a reentrant cavity model of the gun. The resonance parameters work as the input for VORPAL simulations in order to achieve a steady state saturation in the cavity. The simulation results showed that the gun can give rise to electrons beam with high currents and short pulses.

MOPFI046	Transverse RF Kicker Excitation and Longitudinal RF Noise Diffusion for Slow Extraction from SAPT	extraction, kicker, simulation, synchrotron	386
	L. Ouyang, M. Gu, D.M. Li, Q. Yuan, M.Z. Zhang SINAP, Shanghai, People's Republic of China
	Two key techniques used in the slow extraction from synchrotron accelerator: longitudinal RF stochastic noise acceleration, and transverse RF knock out excitation have been studied in this paper. Detailed comparison have revealed the potentials and limits of both methods. For the longitudinal RF stochastic acceleration excitation, the focus has been the phase space compression of particles, which makes the them to hasten around the RF bucket of the cavity, thus to lower the senstivity to ripple. For the transverse RF knock out excitation, the emphasis have been optimal schemes of amplitude modulation and frequency modulation of the RF singals. The optimizations are also used to lower the senstivity of the beam to the ripple and to enhance the uniformity of the extracted beam.

MOPME005	Goubau Line and Beam Characterization of TURBO-ICT for SwissFEL	instrumentation, FEL, electron, laser	476
	S. Artinian, J.F. Bergoz, F. Stulle BERGOZ Instrumentation, Saint Genis Pouilly, France P. Pollet, V. Schlott PSI, Villigen PSI, Switzerland
	SwissFEL will be able to operate with electron bunch doublets 28ns apart. Each of the bunches carries 10pC to 200pC of charge with bunch lengths of a few femto-seconds. For charge calibration of the FEL photon pulses, a measurement accuracy of 1% is desired. The Turbo-ICT accomplishes these requirements with negligible beam position and bunch length dependence. It is insensitive to dark current and features high immunity to background noise. We characterize the Turbo-ICT performance on a Goubau line, also known as single-wire transmission line. The Goubau line utilizes electromagnetic fields with frequencies up to many GHz. It allows accurate bench testing including beam position and bunch length dependence. The results are compared to beam measurements performed at the SwissFEL Injector Test Facility (SITF).

MOPWA071	A Comparison of Electron Cloud Density Measurements at CesrTA	electron, simulation, positron, pick-up	843
	J.P. Sikora, J.A. Crittenden, D.O. Duggins, Y. Li, X. Liu CLASSE, Ithaca, New York, USA S. De Santis LBNL, Berkeley, California, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. Several techniques have been employed to measure the electron cloud (EC) density in accelerators. These include Time Resolved Retarding Field Analyzers (TR-RFA) and Shielded Pickups (SPU) that measure the flux of cloud electrons onto the beam-pipe wall, as well as TE wave resonance techniques that measure the EC density in a region within the volume of the beam-pipe. We have made measurements to test the EC mitigation properties of different surface coatings and geometries, often with more than one technique used in the same test chamber. We present a comparison of bare aluminum chambers with those having a TiN coating, as well as the effect of beam conditioning. In addition, we will compare the results of the different measurement techniques used in the same chamber. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CesrTA) having positron or electron beam energies ranging from 2 GeV to 5 GeV.

MOPWA085	Spin Dynamics Simulations and Horizontal Intrinsic Resonance Studies in the AGS using the Zgoubi Code	polarization, simulation, acceleration, extraction	870
	Y. Dutheil, L. A. Ahrens, H. Huang, F. Méot, V.H. Ranjbar, T. Roser, V. Schoefer, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A critical point for the polarized proton program of the RHIC is the polarization transmission through the AGS acceleration cycle. Recent developments in the Zgoubi model of the AGS allow multi-particle tracking with realistic beam and machine conditions on a large scale computing system. This gives the opportunity to simulate the influence of many beam and machine conditions on the polarization transmission and leads to a better understanding of the depolarization processes, for instance the horizontal intrinsic resonances, that cannot be accurately explored by the conventional simulation approaches or by the experiments with beam. This paper introduces the developments realized on the Zgoubi code to run these simulations and shows some of the latest results.

MOPWO005	Simulating Spin Dynamics and Depolarization using POLE	synchrotron, simulation, polarization, synchrotron-radiation	891
	J.F. Schmidt, O. Boldt, F. Frommberger, W. Hillert ELSA, Bonn, Germany
	Funding: BMBF The spin dynamics in circular accelerators with fast energy ramps, or short storage times of up to some seconds, can be investigated with spin tracking appropriately. Additionally, the spin motion of lepton beams is affected significantly by synchrotron radiation. Hence, spin dynamics simulations require spin tracking with a large number of particles to compute the beam polarization and thus take considerably long computing times. Therefore, high efficiency is crucial to perform systematic polarization studies. The new simulation tool POLE provides the ability to balance accuracy against computing time. To that end, adjustable approximations of magnetic fields and synchrotron radiation are implemented. POLE is accessible for a wide range of lepton storage rings because it uses the common MAD-X lattice files and the corresponding particle tracking results.

MOPWO006	Eigenmode Computation for the GSI SIS18 Ferrite Cavity	cavity, heavy-ion, ion, synchrotron	894
	K. Klopfer, W. Ackermann, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Supported by GSI At the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt the heavy-ion synchrotron SIS18 is operated to further accelerate stable nuclei of elements with different atomic numbers. Two ferrite-loaded cavity resonators are installed within this ring. During the acceleration phase their resonance frequency has to be adjusted to the revolution frequency of the heavy-ions to reflect their increasing speed. To this end, dedicated biased ferrite-ring cores are installed inside the cavities for a broad frequency tuning. By properly choosing a suited bias current, the differential permeability of the ferrite material is modified, which finally enables to adjust the eigenfrequency of the resonator system. Consequently, the actual resonance frequency strongly depends on the magnetic properties of the ferrites. The goal of the current study is to numerically determine the lowest eigensolutions of the GSI SIS18 ferrite-loaded cavity. For this purpose, a new solver based on the Finite Integration Technique has been developed.

MOPWO007	Numerical Calculation of Electromagnetic Fields in Acceleration Cavities Under Precise Consideration of Coupler Structures	dipole, cavity, electromagnetic-fields, impedance	897
	C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by BMBF under contract 05H12RD5 The acceleration with superconducting radio frequency cavities requires dedicated couplers to transfer energy from the radio frequency source to the beam. Simultaneously, higher order mode couplers are installed to effectively suppress parasitic modes. Therefore, the numerical eigenmode analysis based on real-valued variables is no longer suitable to describe the dissipative acceleration structure. At the Computational Electromagnetics Laboratory (TEMF) a robust parallel eigenmode solver to calculate the eigenmodes in the lossy acceleration structure is available. This eigenmode solver is based on complex-valued finite element analysis and utilizes basis functions up to the second order on curved tetrahedral elements to enable the high precision elliptical cavity simulations. The eigenmode solver has been applied to the TESLA 1.3 GHz accelerating cavity to determine the resonance frequency, the quality factor and the corresponding field distribution for all 192 eigenmodes up to the 5th dipole passband (3.12 GHz).

MOPWO026	Investigation of Numerical Precision Issues of Long Term Single Particle Tracking	simulation, dynamic-aperture, beam-beam-effects, HOM	942
	E. McIntosh, R. De Maria, M. Giovannozzi CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. Long term single particle simplectic tracking is one of the most reliable tool to study the dynamic aperture of the circular accelerators. The present computational performance allows to explore the long term behaviour for an extended number of turns. It is well known that for instance single precision floating point arithmetic introduces too much numerical noise even after a moderate number of turns. In this paper we explore the artefacts of the double precision arithmetic that may be visible when the number of turns is in the order of 10⁶, 10⁷.

MOPWO044	Numerical Simulations of a Hollow Electron Lens as a Scraping Device for the LHC	electron, simulation, collimation, proton	993
	V. Previtali, G. Stancari, A. Valishev Fermilab, Batavia, USA S. Redaelli CERN, Geneva, Switzerland
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, Contract No.DE-AC02-07CH11359 with the United States Dep. of Energy. This work was partially supported by US LHC Accelerator Research Program(LARP) The use of hollow electron beam lens for scraping high energy proton beams has been extensively tested at Fermilab's Tevatron collider. In order to evaluate a possible application of a similar a device in the LHC, a dedicated new routine has been implemented in the standard 6D tracking code used at CERN for the design of the LHC collimation system. The effects of a finite length cylinder of electrons encompassing the main proton beam and traveling in the opposite direction is described in the routine. Realistic electron distributions, including measured radial imperfections, have been included in the model. Various operating modes have been simulated for the 7 TeV machine operation with sextupoles and octupoles included. The loss rate caused by the electron lens has been studied through an extended simulation campaign; the obtained halo removal rates for the different electron lens operating modes are presented.

MOPWO050	Comparison of LHC Beam Loss Maps using the Transverse Damper Blow up and Tune Resonance Crossing Methods	collimation, injection, betatron, background	1008
	V. Moens, R. Bruce, S. Redaelli, B. Salvachua, G. Valentino CERN, Geneva, Switzerland V. Moens EPFL, Lausanne, Switzerland G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The LHC collimator settings are qualified regularly via beam loss maps. In this procedure, the beam is artificially excited to create abnormal loss rates. The transverse damper blow up and tune resonance crossing methods are used to increase the betatron amplitude of particles and verify the efficiency of the collimation cleaning and the collimator hierarchy. This paper presents a quantitative comparison of the methods, based on measurements done at different phases of the LHC machine cycle. The analysis is done using Beam Loss Monitor (BLM) with integration times of 1.3 s and 80 ms. The use of the faster BLM data to study the time evolution of the losses in IR3 and IR7 during off-momentum loss maps is also presented.

TUYB103	Status and Plans for the Polarized Hadron Collider at RHIC	polarization, proton, acceleration, luminosity	1106
	M. Bai, L. A. Ahrens, E.C. Aschenauer, G. Atoian, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, O. Eyser, W. Fischer, C.J. Gardner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, A.I. Kirleis, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, V. Schoefer, F. Severino, T.C. Shrey, D. Smirnov, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. As the world’s only high energy polarized proton collider, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) has been providing collisions of polarized proton beams at beam energy from 100~GeV to 255~GeV for the past decade to explore the proton spin structure as well as other spin dependent measurements. With the help of two Siberian Snakes per accelerator plus outstanding beam control, beam polarization is preserved up to 100~GeV. About 10% polarization loss has been observed during the acceleration between 100~GeV and 255~GeV due to several strong depolarizing resonances. Moderate polarization loss was also observed during a typical 8 hour physics store. This presentation will overview the achieved performance of RHIC, both polarization as well as luminosity. The plan for providing high energy polarized He-3 collisions at RHIC will also be covered. This work is on behalf of RHIC team.
	Slides TUYB103 [12.854 MB]

TUPEA012	Rebunching Ultracold Neutrons by Magnetic Deceleration for the neutron EDM experiment at J-PARC	neutron, coupling, 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.

TUPEA029	Theory Calculation of PASER in Gas Mixture Active Medium	electron, laser, wakefield, plasma	1211
	X.F. Tian, C.-F. Wu USTC/NSRL, Hefei, Anhui, People's Republic of China
	In the PASER (particle acceleration by stimulated emission of radiation), the energy stored in an active medium transferred directly to the electron beam passing through in discrete amounts by emitting a photon when the bounded electron returns from upper to lower energy state. In this paper, the wake-field generated by a bunch of electrons traversing in an active medium has been discussed. The calculations of the development of amplitude for gas mixture active medium about CO2 and ArF were made respectively. The results show that the gradient can reach around 1GeV/m. In addition, the electron energy gain occurring as a train of electron micro-bunches traversing in gas mixture was analyzed by a two dimension model. The train of micro-bunches can obviously gain energy from the active medium and the energy exchange is linearly proportional to the interaction length d. The influence of the bunch figure and other quantities on the energy exchange occurring as a train of electron micro-bunches traversing CO2 gas mixture were investigated when the interaction length is 0.5m. The results illustrate that maximum electron energy gain can be obtained by the train of micro-bunches with optimized parameters.

TUPEA056	Concept of Dielectric Wakefield Accelerator Driven by a Long Sequence of Electron Bunches	wakefield, electron, acceleration, injection	1259
	I.N. Onishchenko, V. Kiselev, A. Linnik, G.V. Sotnikov NSC/KIPT, Kharkov, Ukraine
	Funding: This study is supported by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522) The scheme of a two-beam accelerator type is considered that is based on wakefield excitation in rectangular dielectric resonator by a sequence of electron bunches with the aim to enhance wakefield intensity due to multi-bunch coherent excitation, multi-mode summation, and wakefield accumulation in resonator. The sequence of bunches can be divided into exciting and accelerated parts in any proportion by means at the proper detuning of bunch repetition frequency relative to the frequency of principle eigen mode of the resonator. A train of 6000 electron bunches, each of energy 4.5МeV, charge 0.16nC, duration 60psec, diameter 1.0cm, and angular spread 0.05 mrad is produced with the linear resonant accelerator. Bunch repetition frequency is 2805 MHz and can be varied within 2MHz by changing master oscillator frequency. Bunches are injected into copper rectangular waveguide of cross-section 8.5x18.0cm² and length 75cm along wide sides of which Teflon plates are placed. The plate thickness is chosen 1.67cm so that the frequency of excited eigen mode coincides with bunch repetition frequency.

TUPEA066	Metamaterial-based Accelerating, Bending and Focusing Structures	focusing, electron, quadrupole, vacuum	1286
	I. McGregor The University of Liverpool, Liverpool, United Kingdom K.M. Hock Cockcroft Institute, Warrington, Cheshire, United Kingdom
	We report on the progress of our research into metamaterial-based accelerating, bending and focusing structures at the Cockcroft Institute. The effort during the last year has been directed towards designing and investigating practical RF structures that are suitable for industrial and medical applications. We have shown that, by introducing structures based on metamaterial resonators, RF accelerating structures can be made more compact and higher gradient. This year, we will concentrate on focusing and bending structures.

TUPFI063	Electromagnetic Coupling between High Intensity LHC Beams and the Synchrotron Radiation Monitor Light Extraction System	simulation, impedance, extraction, synchrotron	1493
	F. Roncarolo, W. Andreazza, A. Bertarelli, E. Bravin, F. Caspers, M. Garlaschè, A. Goldblatt, J-J. Gras, O.R. Jones, T. Lefèvre, E. Métral, A.A. Nosych, B. Salvant, G. Trad, R. Veness, C. Vollinger, M. Wendt CERN, Geneva, Switzerland
	The CERN LHC is equipped with two Synchrotron Radiation Monitor systems used to characterise transverse and longitudinal beam distributions. Since the end of the 2011 LHC run the light extraction system, based on a retractable mirror, has suffered deformation and mechanical failure that is correlated to the increase in beam intensity. Temperature probes have associated these observations to a strong heating of the mirror support with a dependence on the longitudinal bunch length and shape, indicating the origin as electromagnetic coupling between the beam and the structure. This paper combines all this information with the aim of characterising and improving the system in view of its upgrade during the current LHC shutdown. Beam-based observations are presented along with electromagnetic and thermomechanical simulations and complemented by laboratory measurements, including the study of the RF properties of different mirror bulk and coating materials.

TUPFI068	High Power Tests of Alumina in High Pressure RF Cavities for Muon Ionization Cooling Channel	cavity, pick-up, collider, klystron	1508
	L.M. Nash University of Chicago, Chicago, Illinois, USA G. Flanagan, R.P. Johnson, F. Marhauser, J.H. Nipper Muons. Inc., USA M.A. Leonova, A. Moretti, M. Popovic, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, USA Y. Torun IIT, Chicago, Illinois, USA
	It is important to make a compact muon ionization cooling channel to increase the cooling efficiency (muon survival rate, cooling decrement, etc). A proposed scheme to reduce the radial size of RF cavities at a given resonance frequency is to insert a dielectric material into the RF cavity. In vacuum cavities, however, dielectric materials are extremely susceptible to breakdown in high power conditions. High-pressure hydrogen gas has been shown to inhibit breakdown events in RF cavities in strong magnetic fields. An experiment has been designed to test surface breakdown of alumina in RF cavities. A structure has been designed to maximize the parallel field parallel to the surface while bringing the cavity into a desired frequency range (800-810MHz). Alumina is tested in this configuration under high power conditions. The experimental result will be shown in this presentation.

TUPFI083	Simulation Study of Head-on Beam-beam Compensation with Realistic RHIC Lattices	lattice, dynamic-aperture, proton, simulation	1541
	Y. Luo, M. Bai, W. Fischer, C. Montag, V.H. Ranjbar, S. Tepikian BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We performed numerical simulations to study the effects of head-on beam-beam compensation with the realistic RHIC lattices. To better cancel the beam-beam resonance driving terms during half beam-beam compensation operation, the betatron phase advances between the interaction point IP8 and the center of the electron lens should be multiples of pi. for this purpose two shunt power supplies were added to the main quadrupole circuit buses in the arc between them. For the realistic beam-beam compensation lattices, the integer tunes are (27, 29) for the Blue ring and (29, 30) for the Yellow ring. The betatron phase advances between IP8 and the e-lens are (8pi,11pi) in the Blue ring and (11pi, 9pi) in the Yellow ring. Recent simulation results will be presented.

TUPFI084	RHIC Polarized Proton Operation for 2013	emittance, lattice, polarization, injection	1544
	V.H. Ranjbar, L. A. Ahrens, E.C. Aschenauer, M. Bai, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, W. Fischer, C.J. Gardner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, A.I. Kirleis, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V. Ptitsyn, G. Robert-Demolaize, T. Roser, W.B. Schmidke, V. Schoefer, F. Severino, T.C. Shrey, D. Smirnov, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang BNL, Upton, Long Island, New York, USA O. Eyser UCR, Riverside, California, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The 2013 operation of the Relativistic Heavy Ion Collider (RHIC) marks the second year of running under the RHIC II era. Additionally this year saw the implementation of several important upgrades designed to push the intensity frontier. Two new E-lenses have been installed, along with a new lattice designed for the E-lens operation. A new polarized proton source which generates about factor of 2 more intensity was commissioned as well as a host of RF upgrades from a new longitudinal damper, Landau cavity in RHIC to a new low level RF and new harmonic structure for the AGS. We present an overview of the challenges and results from this years run.

TUPME001	Effect of Self-consistency on Space Charge Induced Beam Loss	simulation, space-charge, emittance, controls	1556
	G. Franchetti GSI, Darmstadt, Germany
	In long term storage space charge driven incoherent effect may lead to a slow beam diffusion that causes emittance growth and beam loss. However, when beam loss are relevant the full mechanism cannot be understood only driven by an incoherent effect. In this proceeding the issue of the self-consistency is discussed, and its impact presented for simplified examples and for the SIS100.

TUPME004	Spin Tracking at the International Linear Collider	dipole, polarization, positron, damping	1565
	V.S. Kovalenko, G.A. Moortgat-Pick, A. Ushakov University of Hamburg, Hamburg, Germany S. Riemann DESY Zeuthen, Zeuthen, Germany M. Vogt DESY, Hamburg, Germany A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Optimization", contract number 19XL7Ic4 In the baseline design for the International Linear collider an helical undulator-based positron source has been chosen that can provide positrons with a polarization of 60% as an upgrade option motivated by physics reasons. But even the baseline configuration would already provide about 30%. In order to match the high precision requirements from physics and to optimize the physics outcome one has to control systematic uncertainties to a very high level. Therefore it is needed to run both beams polarized but provide also an unpolarized set-up for control reasons. In our study we present results on precise spin tracking and propose also an minimal machine set-up to run in an unpolarized mode within the baseline design.

TUPME009	Measurement and Vibration Studies on the Final Focus Doublet at DAΦNE and new collider Implications	damping, collider, luminosity, factory	1580
	S. Tomassini INFN/LNF, Frascati (Roma), Italy
	Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu-CARD, grant agreement no. 227579. A Super Flavour Factory, to be built in the Tor Vergata University campus near Frascati, Italy, will have nano-beams in order to reach the design luminosity. The knowledge and compensation of the vibrations induced on the beams by the anthropic noise is then fundamental. The DAΦNE Phi-factory at LNF, Frascati, was upgraded in the second half of 2007 in order to implement the large Piwinski angle and crab waist collision scheme and in 2010 the KLOE experiment was rolled in for a new data taking and physic program. A measurement campaign has been performed on DAΦNE to find out the actual vibration sensitivity of the final focus doublets. Vibration measurements were performed on the Final Focus doublet because of luminosity losses and photon beam lines instability evidences. Results and stabilization technique to mitigate the effects of the ground motion induced by the “cultural noise” are presented. Implications on the design and stabilization of a Flavour Factory Final Focus doublets will be discussed.

TUPME012	Space Charge Simulation based on a Measured Optics in J-PARC MR	optics, space-charge, sextupole, coupling	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.

TUPME016	Crosstalk Between Beam-beam Interaction and Lattice Nonlinearities in the SuperKEKB	simulation, luminosity, lattice, betatron	1601
	D. Zhou, K. Ohmi, Y. Ohnishi, K. Oide, H. Sugimoto KEK, Ibaraki, Japan
	Momentum-dependent lattice nonlinearities have been proven to be important for the luminosity performance in the KEKB B-factory. As an upgrade of KEKB, the SuperKEKB adopts nano-beam scheme, in which the colliding beams are squeezed to extremely small sizes at the interaction point. Consequently, the lattice nonlinearities in SuperKEKB become more stronger than in KEKB. Using two codes, SAD and BBWS, we did various simulations to study the crosstalk between beam-beam interaction and lattice nonlinearities. It is found that lattice nonlinearities can cause remarkable luminosity loss in the SuperKEKB.

TUPME033	Evaluation of the Beam Coupling Impedance of New beam Screen Designs for the LHC Injection Kicker Magnets	impedance, kicker, coupling, injection	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.

TUPME060	Tune Studies with Beam-Beam Effects in LHC	emittance, simulation, luminosity, collider	1703
	S. Paret, J. Qiang LBNL, Berkeley, California, USA R. Alemany-Fernandez, X. Buffat, R. Calaga, K. Cornelis, M. Fitterer, R. Giachino, W. Herr, A. Macpherson, G. Papotti, T. Pieloni, S. Redaelli, F. Roncarolo, M. Schaumann, R. Suykerbuyk, G. Trad CERN, Geneva, Switzerland R. Miyamoto ESS, Lund, Sweden
	Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231. In high brightness colliders, the tune spread due to the collisions has a significant impact on the quality of the beams. The impact of the working point on emittance growth and beam lifetime has been observed in beam experiments in LHC. Strong-strong beam-beam simulations that were accomplished to better understand such observations are shown. Compared to experiments, wide ranged parameter scans can be done easily. Tune footprints and scans of the emittance growth obtained from simulations are discussed. Three cases are considered: Very high intensity, moderate intensity and collisions with separated beams.

TUPME061	Emittance Growth with Crab Cavity and Damper Noise in LHC	emittance, simulation, pick-up, damping	1706
	S. Paret, J. Qiang LBNL, Berkeley, California, USA
	Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231. Strong-strong beam-beam simulations are employed to investigate the noise sensitivity of the emittance in the future High Luminosity (HL)-LHC. Noise in the accelerator causes fluctuations of the bunch centroids at the interaction points (IPs) which cause emittance growth for large beam-beam parameters. Two noise sources are examined: Crab cavities and the transverse damper. The damper noise is adjusted to bring simulations in agreement with an emittance measurement in a past LHC run. Results from simulations with HL-LHC beam parameters using different noise levels, damper gains and working points are discussed.

TUPME064	Envelope Perturbations in a Space-Charge-Dominated Electron Beam	simulation, space-charge, quadrupole, lattice	1712
	W.D. Stem, B.L. Beaudoin, I. Haber, R.A. Kishek, T.W. Koeth UMD, College Park, Maryland, USA
	Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office. Linear perturbation analysis of the RMS envelope equations predicts a frequency splitting of the transverse envelope resonances with the onset of space charge. These resonances are a potential source of beam degradation for space-charge-dominated particle accelerators and storage rings. We use WARP for both envelope code integration and particle-in-cell (PIC) simulations to predict the behavior of these resonances for an existing alternating gradient lattice storage ring. The focus of these simulations is tailored toward examining physics that is scalable to future high-intensity accelerators. This paper provides detailed simulation results and a design for an experimental demonstration at the University of Maryland Electron Ring (UMER), a high intensity 10 keV electron storage ring.

TUPWA007	Method and Results of Systematic Beam Matching to a Periodic DTL	emittance, DTL, focusing, quadrupole	1733
	L. Groening, W.A. Barth, P. Forck, I. Hofmann, S.G. Yaramyshev GSI, Darmstadt, Germany D. Jeon IBS, Daejeon, Republic of Korea
	Systematic investigations on high current 3d-beam matching to a periodic Alvarez-type DTL are reported. Twiss parameters at the entrance of a matching section to the periodic structure were concluded from transverse and longitudinal measurements. Periodic solutions in 3d were calculated including space charge using the measured rms emittances. The matching was performed by rms beam size tracking and employing a numerical routine to set the matching section, which comprises five quadrupoles and two bunchers. Matching allowed for significant emittance growth reduction and for verification of non-linear beam dynamics effects along the DTL.

TUPWA010	A Trial to Reduce the Kicker Impedance of 3-GeV RCS in J-PARC	kicker, impedance, acceleration, status	1742
	Y. Shobuda, N. Hayashi, T. Takayanagi JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Irie KEK, Ibaraki, Japan T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	At 3GeV RCS in J-PARC, the kicker impedance has been considered to be the dominant source to cause the beam instability. Recently, experimental studies demonstrate that the beam instability is suppressed by reducing the kicker impedance. In this report, a trial to reduce the kicker impedance is reported.

TUPWA011	Investigation of Emittance Growth in a Small PET Cyclotron CYCIAE-14	cyclotron, emittance, extraction, simulation	1745
	M. Li, Shizhong. An, T.J. Zhang CIAE, Beijing, People's Republic of China
	In order to satisfy the rapidly increased domestic needs for PET in China, a small medical cyclotron named CYCIAE-14 is designed and constructed in CIAE ( China Institute of Atomic Energy ) . As the beam intensity in CYCIAE-14 is high, the beam emittance should be controlled strictly in order to reduce the beam loss in the cyclotron. Precessional mixing and resonance crossing are the two main factors leading to emittance growth in the cyclotron with stripping extraction. In this paper, the physical mechanism of precessional mixing in a stripping extraction cyclotron is investigated. After that, the maximum allowable field errors in CYCIAE-14 are derived using the Hamiltonian formalism and numerical simulation, which provides a reference for the cyclotron design and field shimming.

TUPWA012	The Influence of the Magnetic Field Errors in CYCIAE-100 Cyclotron	emittance, cyclotron, simulation, TRIUMF	1748
	H.J. Yao, M. Li, T.J. Zhang, J.Q. Zhong CIAE, Beijing, People's Republic of China
	The main magnet size of CYCIAE-100 is 2.31 m in height and 6.16 m in diameter and the outer radius of the sector is 2.0 m, and the total iron weight is about 415t. The magnetic filed can not be absolutely ideal because of imperfections during manufacturing and installation of this big magnet. Therefore the influence of the magnetic field errors on the beam behavior should be studied to provide the reference for magnet mapping and shimming. Magnetic field errors in a cyclotron will excite coherent oscillations through displacing the center of orbit or distorting the transverse phase space. This effect is especially important in the CYCIAE-100 cyclotron because there are a number of different turns in the extracted beam. The tolerances for the magnetic field errors are given in this paper based on analytic calculations and numerical simulations. The resonances vr=1, 2vr=2 driven by the 1st, 2nd harmonic magnetic field are considered, which will result in the radial emittance growth .Besides that, the resonances cause the vertical emittance growth are considered. The maximum allowable field errors for CYCIAE-100 are presented in this paper.

TUPWA034	On the Choice of Linac Parameters for Minimal Beam Losses	space-charge, linac, emittance, beam-losses	1787
	M. Eshraqi ESS, Lund, Sweden J.-M. Lagniel GANIL, Caen, France
	In high intensity linear accelerators, the tune spreads induced by the space-charge forces in the radial and longitudinal planes are key parameters for halo formation and beam losses. For matched beams they are the parameters governing the number of resonances (including coupling resonances) which affect the beam and determine the respective sizes of the stable and halo areas in phase space. The number and strength of the resonances excited in mismatched beams leading to even higher amplitude halos are also directly linked to the tune spreads. In this paper, the equations making the link between the basic linac parameters (rf frequency, zero-current phase advances, beam intensity and emittances) and the tune spreads are given. A first analysis of the way these linac parameters can be chosen to minimize the tune spreads is presented. The parameters of ESS linac are used for this study.

TUPWA039	Identification of the SPS Impedance at 1.4 GHz	impedance, optics, simulation, bunching	1793
	T. Argyropoulos, T. Bohl, H. Damerau, J. Esteban Müller, E.N. Shaposhnikova, H. Timko CERN, Geneva, Switzerland
	In the SPS spectrum measurements of very long single bunches were used in the past to identify sources of longitudinal microwave instability. Shielding of the identified objects significantly improved the beam stability. However, longitudinal instabilities are still one of the limitations for high intensity LHC beams in the SPS. Recently the same measurement technique was used again, revealing a strong high frequency resonance. During the slow de-bunching with the RF switched off, the presence of different resonant impedances leads to a line density modulation at the resonant frequencies. Longitudinal profiles of bunches of various intensities were acquired. For sufficiently high intensities their spectra show a fast growing and strong modulation at 1.4 GHz. Measurements using two transverse optics with different transition energy are compared. Reproducing the measurements with numerical simulations, including the known SPS longitudinal impedances, allowed the parameter range of this unknown source to be determined. Possible candidates as impedance sources in the SPS ring are investigated.

TUPWA042	Lessons Learned and Mitigation Measures for the CERN LHC Equipment with RF Fingers	impedance, vacuum, damping, simulation	1802
	E. Métral, O. Aberle, R.W. Aßmann, V. Baglin, M.J. Barnes, O.E. Berrig, A. Bertarelli, G. Bregliozzi, S. Calatroni, F. Carra, F. Caspers, H.A. Day, M. Ferro-Luzzi, M.A. Gallilee, C. Garion, M. Garlaschè, A. Grudiev, J.M. Jimenez, O.R. Jones, O. Kononenko, R. Losito, J.L. Nougaret, V. Parma, S. Redaelli, B. Salvant, P.M. Strubin, R. Veness, C. Vollinger, W.J.M. Weterings CERN, Geneva, Switzerland
	Beam-induced RF heating has been observed in several LHC components when the bunch/beam intensity was increased and/or the bunch length reduced. In particular eight bellows, out of the ten double-bellows modules present in the machine in 2011, were found with the spring, which should keep the RF fingers in good electrical contact with the central insert, broken. Following these observations, the designs of all the components of the LHC equipped with RF fingers have been reviewed. The lessons learnt and mitigation measures are presented in this paper.

TUPWA043	Impedance Studies for VMTSA Module of LHC Equipped with RF Fingers	impedance, simulation, factory	1805
	O. Kononenko, F. Caspers, A. Grudiev, E. Métral, B. Salvant CERN, Geneva, Switzerland
	During 2011 run of LHC it was found that beam-induced heating causes many issues for accelerator components. Particularly some of the double-bellow modules, called VMTSA modules, were found to have deformed RF fingers and a broken spring which ensured good contact between them and a central insert. Impedance studies have been performed for different types of nonconformities and benchmarked against measurements. It was found that even a small gap between the fingers and a central insert could be fatal for the VMTSA operation. Results of this study were an input for the further thermal analysis.

TUPWA062	Dependence of Beam Instabilities Caused by Electron Clouds at CesrTA on Variations in Bunch Spacing and Chromaticity	electron, damping, dipole, positron	1844
	M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, R.E. Meller, M.A. Palmer, G. Ramirez, N.T. Rider, K.G. Sonnad, H.A. Williams CLASSE, Ithaca, New York, USA R.F. Campbell, R. Holtzapple, M. Randazzo CalPoly, San Luis Obispo, California, USA J.W. Flanagan KEK, Ibaraki, Japan
	Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867 and the Lepton Collider R&D Coop Agreement: NSF Award PHY-1002467 Experiments have been performed at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) to probe the interaction of the electron cloud with a 2.1 Gev stored positron beam. The purpose of these experiments was to characterize the dependence of beam–electron cloud interactions on the bunch spacing and the vertical chromaticity. These experiments were performed on a 30-bunch positron train, at a fixed current of 0.75mA/bunch. The bunch spacing was varied between 4 and 28 ns at three different vertical chromaticity settings. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated Beam Position Monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches within these different trains.

TUPWA067	Beam Emittance Growth Effects in High-intensity RFQ	rfq, emittance, linac, space-charge	1859
	Y.K. Batygin, R.W. Garnett, L. Rybarcyk LANL, Los Alamos, New Mexico, USA
	Beam dynamics in an RFQ are strongly affected by coupling between transverse and longitudinal particle oscillations. The adiabatic process of high-intensity bunched beam formation results in equipartitioning in the RFQ, which determines the longitudinal beam emittance. Avoiding parametric resonances is an important design criterion to prevent significant emittance growth of the beam. Manufacturing errors can result in beam emittance growth and reduction of beam transmission. This paper will present the results of a study where analytical and numerical evaluations were performed to determine the effect of the aforementioned factors on beam quality in a high-current RFQ.

TUPWA071	Studies of Resistive Wall Heating at JLAB FEL	impedance, FEL, wiggler, electron	1868
	R. Li, S.V. Benson JLAB, Newport News, Virginia, USA
	Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. When the JLAB FEL is under CW operation, it had been observed that temperature rises over the wiggler vacuum chamber, presumably as the result of the power deposition on the resistive wall of the wiggler chamber. Previous analyses have been done on the resistive wall impedance for various cases, such as DC, AC, and anomalous skin effects. Here we report an investigation on the beam kinetic energy losses for each of these cases. This study includes the non-ultrarelativistic effect on resistive wall loss, for both round pipe and parallel plates. We will present the comparison of our results with the measured data obtained during CW operation of the JLAB FEL. Other possible factors contributing to the measured heating will also be discussed. K. Bane and G. Stupakov, SLAC-PUB-10707, 2004.

WEOAB102	CSR-driven Longitudinal Single Bunch Instability Thresholds	impedance, synchrotron, damping, electron	2041
	P. Kuske BESSY GmbH, Berlin, Germany
	According to Bane, et al.* threshold currents should follow a quite simple scaling law. More detailed theoretical results for the underlying shielded CSR-interaction have been performed for BESSY-II and the MLS and will be presented in comparison with observations at these storage rings. It is found that there are parameter regions where the instability is weak and thus thresholds depend on damping time and synchrotron tune. Theoretical findings are in surprisingly good agreement with most of the observed instability features. * K.L. Bane, et al., Phys. Rev. ST-AB 13, 104402 (2010)
	Slides WEOAB102 [0.779 MB]

WEPWA047	Longitudinal Stability of Multiturn ERL with Split Accelerating Structure	linac, electron, simulation, cavity	2226
	Ya.V. Getmanov, O.A. Shevchenko, N. Vinokurov BINP SB RAS, Novosibirsk, Russia T. Atkinson HZB, Berlin, Germany N. Vinokurov KAERI, Daejon, Republic of Korea
	Some modern projects of the new generation light sources use the conception of multipass energy recovery linac with split (CEBAF-like) accelerating structures. One of the advantages of these light sources is the possibility to obtain a small longitudinal beam size. To help reduce it, the longitudinal dispersion should be non-zero in some arcs of the accelerator. However small deviations in voltages of the accelerating structures can be enhanced by induced fields from circulating bunches due to the dependence of the flight time on the energy spread and the high quality factor of the superconducting radio-frequency cavities. Therefore, instabilities related with interactions of the electron bunches and longitudinal modes of the cavities can develop in the installation. Stability conditions for the interactions with fundamental accelerating mode of the split accelerating system are discussed. Numerical simulations are made for two projects - MARS and FSF.

WEPWO005	Microphonics Analysis of the SC 325 MHz CH-Cavity	cavity, simulation, vacuum, status	2319
	M. Amberg, M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg, K. Aulenbacher HIM, Mainz, Germany K. Aulenbacher IKP, Mainz, Germany
	Since the walls of superconducting (sc) cavities are kept very thin to support the cooling process, even small mechanical disturbances can detune the cavity. One of the main sources of detuning a cavity is microphonics. These low-frequent vibrations caused by vacuum pumps or underground noise are transferred to the cryostat and excite mechanical resonances of the cavity which may lead to frequency shifts larger than the bandwidth. To determine the mechanical resonance frequencies of the sc 325 MHz CH-cavity (Crossbar-H-Mode) simulations with ANSYS Workbench have been performed in a first step. Additionally, microphonics measurements were taken at room temperature as well as in a vertical cryostat at 4K in the cryo-lab of the IAP, Frankfurt University. Furthermore, the contraction of the cavity walls and the resulting frequency shift due to the cavity cool-down has been measured. A comparison between simulation results and the measured values is presented in this paper.

WEPWO008	SRF Conical Half-wave Resonator Tuning Developments	cavity, simulation, target, cryomodule	2325
	E.N. Zaplatin FZJ, Jülich, Germany A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302. A conical Half-Wave Resonator is considered as an option for a first accelerating cavity for β=v/c=0.11 with the resonance frequency 162.5 MHz for a high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory (Project X). We present results of different options of the cavity mechanical tuning. The "standard" tuning method of beam port deformations is an effective tuning method still requiring a relatively high tuning pressure. The side tuning is considered as a novel option for the resonance frequency adjustment featuring lower tuning force and an option of the structure design for the resonator frequency shift self compensation.

WEPWO056	Update of the Mechanical Design of the 650 MHZ β=0.9 Cavities for Project X	cavity, simulation, niobium, linac	2432
	I.V. Gonin, M.H. Awida, M.H. Foley, C.J. Grimm, T.N. Khabiboulline, Y.M. Pischalnikov, V.P. Yakovlev Fermilab, Batavia, USA
	Five-cell elliptical 650 MHz β=0.9 cavities to accelerate 1 mA of average H⁻ beam current in the range 520-3000 MeV of the Project X Linac are currently planned. We will present the results of optimization of mechanical design of cavities with their Helium Vessel. We discuss the efforts to optimize the mechanical stability of the cavity versus the Helium bath pressure fluctuations, cavity tunability. We present also modal and thermal analysis; discuss tuner options and other issues.

WEPWO058	Recent Progress at Fermilab Controlling Lorentz Force Detuning and Microphonics in Superconducting Cavities	cavity, controls, cryomodule, SRF	2438
	W. Schappert, Y.M. Pischalnikov Fermilab, Batavia, USA
	Funding: Work is supported by U.S. Department of Energy SRF cavities are susceptible to detuning by mechanical deformations induced by the Lorentz force and microphonics. Providing the RF overhead required to maintain the accelerating gradient in detuned cavities can increase both the capital and operating costs of superconducting accelerators. Recent work at Fermilab has shown that active vibration control using a piezo actuator can reduce both Lorentz Force detuning and microphonics to the point where negligible RF overhead is required to maintain the accelerating gradient.

WEPWO086	Split Higher Order Modes in Superconducting Cavities	cavity, dipole, HOM, higher-order-mode	2495
	H. Hahn, S.A. Belomestnykh, W. Xu BNL, Upton, Long Island, New York, USA
	Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE and award no. DE-SC0002496 to Stony Brook University with the US DOE. Split resonances are a common appearance in superconducting cavities and were studied here on the specific example of the TE11 dipole resonance in five-cell copper models of the ERL and BNL3. The BNL3 cavity was designed to be suitable for the envisioned electron-hadron collider eRHIC. Achieving the required high-current performance depends on avoiding beam break-up instabilities by minimizing the Higher Order Modes (HOM) Q-values. This was attempted in the design phase and will be done with appropriate mode dampers in operation. The availability of a copper model provided a convenient opportunity to confirm the design and to study potentially nefarious high-Q resonances. The appearance of split resonances impeded the HOM identification and the theoretical interpretation as elipticity deformation is presented in this report.

WEPEA001	Simulation Studies of Longitudinal RF-noise and Phase Displacement Acceleration as Driving Mechanism for the MedAustron Synchrotron Slow Extraction	extraction, acceleration, simulation, synchrotron	2501
	U. Dorda EBG MedAustron, Wr. Neustadt, Austria M. Benedikt, H.O. Schönauer, A. Wastl CERN, Geneva, Switzerland
	MedAustron is a synchrotron based hadron therapy and research facility located in Austria currently entering the installation stage. It is an implementation of the CERN-PIMMS design which proposed induction acceleration by a betatron core as the driving mechanism for the third-order slow resonant extraction. Primarily in order to increase the accelerators flexibility towards future irradiation schemes but also as back-up options, two alternative extraction driving mechanism have been studied: Longitudinal RF-noise and phase displacement acceleration. The advantages as well as the corresponding limitations are explained, analytical estimates and particle tracking results performed with the 2D tracking codes LONG1D and a specifically developed Python based simulation code are presented.

WEPEA018	Further Improvement of the PTC-ORBIT Code to Model Realistic Operation of High-beam Power Synchrotrons	injection, synchrotron, quadrupole, extraction	2534
	A.Y. Molodozhentsev, E. Forest KEK, Ibaraki, Japan
	The combined PTC-ORBIT code has been developed a few years ago to study the dynamics of the high intensity proton beams in synchrotrons, including the nonlinear machine resonances and the space charge effects in the self-consistent manner. In order to extend the code abilities the time variation of the main elements of the synchrotron has been introduced into the PTC module of the code. This feature opens the direct way to model the multi-turn injection process and the slow extraction process by using realistic machine description, in particular the dynamic variation of the betatron tunes, strength of the bump magnets, dynamic resonance correction or resonance excitation. To demonstrate the code abilities the corresponding simulations for CERN PS Booster and for J-PARC Main Ring are discussed.

WEPEA021	Influence of the Vacuum Chamber Limitation on Dynamic Aperture Calculations	dynamic-aperture, vacuum, multipole, optics	2543
	M. Attal SESAME, Allan, Jordan
	In a storage ring the evaluation of the dynamic aperture taking into account the vacuum chamber limitation is more accurate and may display nonlinearities that could not be seen in the conventional absolute dynamic aperture calculations. This has been investigated in this paper and demonstrated in SESAME dynamic aperture case where taking into account the vacuum chamber uncovered the seriousness of a 5th order resonance mainly when errors like high order multipoles were introduced to the lattice. The destructive effect of the 5th order resonance has been avoided by changing the fractional part of the tunes. The problem has also been more investigated using the Frequency Map Analysis technique.

WEPEA023	Space Charge Effects for Different CSNS/RCS Working Points	lattice, simulation, space-charge, emittance	2549
	S.Y. Xu, N. Wang, S. Wang IHEP, Beijing, People's Republic of China
	The China Spallation Neutron Source (CSNS) operates at 25 Hz repetition rate with the design beam power of 100 KW. CSNS consists of an 80-MeV linac and a 1.6-GeV Rapid Cycling Synchrotron (RCS). Due to the high beam density and high repetition rate for CSNS/RCS, the rate of beam loss must be controlled to a very low level. The major source of beam loss is associated with resonances. Thus, choosing he best suitable working points on the tune diagram is important to reach low beam loss. Different tune areas are explored and compared by considering resonances and the effects of space charge, which can drive particles into the excited resonances. Different working points are simulated and compared by using the codes ORBIT and SIMPSONS.

WEPEA031	Slow extraction design in HIMM	extraction, synchrotron, septum, emittance	2567
	J. Shi, W.P. Chai, J.W. Xia, J.C. Yang, Y.J. Yuan IMP, Lanzhou, People's Republic of China
	A heavy ion medical machine(HIMM) is proposed for cancer therapy in Lanzhou, China. The slow extraction design of the synchrotron is introduced in this paper. Eight sextupoles are used, four of them are for correcting the chromaticity and the rest for driving the 3rd-order resonance. In order to save the aperture of vacuum chamber, a 3-magnet bump is adopted during the extraction process. The phase space map in the entrance of the electrostatic septum and the last 3 turns' particle trajectory before particle extraction are given.

WEPEA034	Study on the Beam Dynamics in the RISP Driver Linac	linac, quadrupole, stripper, ion	2576
	H.J. Kim, H.J. Jang, D. Jeon IBS, Daejeon, Republic of Korea J.G. Hwang Kyungpook National University, Daegu, Republic of Korea E.-S. Kim KNU, Deagu, Republic of Korea
	Abstract Rare Isotope Science Project (RISP) has been proposed as a multi-purpose accelerator facility for providing beams of exotic rare isotopes of various energies. The RISP driver linac which is used to accelerate the beam, for an example, Uranium ions from 0.3 MeV/u to 200 MeV/u consists of superconducting RF cavities and warm quadrupole magnets for focusing heavy ion beams. Requirement of the linac design is especially high for acceleration of multiple charge beams. In this paper, we present the requirements of dynamic errors and correction schemes to minimize the beam centroid oscillation and preserve beam losses under control.

WEPEA042	The PS Upgrade Programme: Recent Advances	injection, electron, emittance, extraction	2594
	S.S. Gilardoni, S. Bart Pedersen, C. Bertone, N. Biancacci, A. Blas, D. Bodart, J. Borburgh, P. Chiggiato, H. Damerau, S. Damjanovic, J.D. Devine, T. Dobers, M. Gourber-Pace, S. Hancock, A. Huschauer, G. Iadarola, L.A. Lopez Hernandez, A. Masi, S. Mataguez, E. Métral, M.M. Paoluzzi, S. Persichelli, S. Pittet, S. Roesler, C. Rossi, G. Rumolo, B. Salvant, R. Steerenberg, G. Sterbini, L. Ventura, J. Vollaire, R. Wasef, C. Yin Vallgren CERN, Geneva, Switzerland M. Migliorati University of Rome "La Sapienza", Rome, Italy
	The LHC Injectors Upgrade project (LIU) has been initiated to improve the performances of the existing injector complex at CERN to match the future requirements of the HL-LHC. In this framework, the Proton Synchrotron (PS) will undergo fundamental changes for many of its main systems: the injection energy will be increased to reduce space-charge effects, the transverse damper will be improved to cope with transverse instabilities the RF systems will be upgraded to accelerate higher beam intensity and brightness. These hardware improvements are triggered by a series of studies meant to identify the most critical performance bottlenecks, like space charge, impedances, longitudinal and transverse instabilities, as well as electron-cloud. Additionally, alternative production schemes for the LHC-type beams have been proposed and implemented to circumvent some of the present limitations. A summary of the most recent advances of the studies, as well as the proposed hardware improvements is given.

WEPEA043	Working Point and Resonance Studies at the CERN PS	injection, controls, octupole, focusing	2597
	A. Huschauer, M. Benedikt, H. Damerau, P. Freyermuth, S.S. Gilardoni, R. Steerenberg, B. Vandorpe CERN, Geneva, Switzerland
	The increase of luminosity demanded by the High Luminosity LHC (HL-LHC) requires an increase of beam intensity, which might result in instabilities appearing at injection energy in the CERN PS. Transverse head-tail instabilities have already been observed on operational LHC beams and a stabilizing mechanism as an alternative to linear coupling is currently being studied. It consists of reducing the mode number of the transverse oscillation by changing linear chromaticity and in succession completely suppressing the instability by a transverse damper system with appropriate bandwidth. Therefore, a chromaticity correction scheme at low energy exploiting the intrinsic possibilities offered by special circuits mounted on top of the main magnet poles, the Pole Face Windings (PFW), has been examined. The presence of destructive betatron resonances, which restrict the choice of the injection working point and the maximum acceptable tune spread, forms an additional limitation for high-brightness and high-intensity beams in the CERN PS. To improve the current working point control scheme, the influence of the P F W on the machine resonances is presented in this paper.

WEPEA052	Investigations on CERN PSB Beam Dynamics with Strong Direct Space Charge Effects Using the PTC-ORBIT Code	simulation, emittance, space-charge, injection	2621
	V. Forte, E. Benedetto, C. Carli, M. Martini, B. Mikulec, E. Métral, F. Schmidt CERN, Geneva, Switzerland A.Y. Molodozhentsev KEK, Ibaraki, Japan
	The CERN PS Booster (PSB) is the first synchrotron of the LHC injector chain consisting out of four superposed rings and providing beam for many users. As part of the LIU project, the machine will be upgraded. Space charge and resonances are serious issues for the good quality of the beam at injection energy. Consequently simulations are needed to track the beam in the machine taking into account space charge effects: PTC-ORBIT has been used as tracking code. This paper presents simulations results compared with the measurements for machine performances evaluation and code-benchmarking purposes.

WEPEA054	CERN PS Optical Properties Measured with Turn-by-turn Orbit Data	simulation, optics, extraction, kicker	2627
	C. Hernalsteens, T. Bach, S.S. Gilardoni, M. Giovannozzi, A. Lachaize, G. Sterbini, R. Tomás, R. Wasef CERN, Geneva, Switzerland
	The performance of the PS has been constantly increasing over the years both in terms of beam parameters (intensity and brightness) and beam manipulations (transverse and longitudinal splitting). This implies a very good knowledge of the linear and non-linear model of the ring. In this paper we report on a detailed campaign of beam measurements based on turn-by-turn orbit data aimed at measuring the optics in several conditions as well as the resonance driving terms. The goal of this study is to assess whether any specific correction system should be envisaged to achieve the required future performance.

WEPEA055	Quantitative Evaluation of Trapping and Overall Efficiency for Simple Models in One-degree of Freedom	simulation, controls, synchrotron, extraction	2630
	C. Hernalsteens, C. Frye, M. Giovannozzi CERN, Geneva, Switzerland A. Bazzani Bologna University, Bologna, Italy
	A key ingredient for the Multi-Turn Extraction at the CERN Proton Synchrotron is the beam trapping in stable islands of transverse phase space. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, a method allowing an analytical estimation of the fraction of beam trapped into stable islands as a function of the Hamiltonian parameters is presented for a very simple model of the dynamics (pendulum) and is extended to the case of the interpolating Hamiltonian of the Hénon model, the latter being a good 2D model of the MTE dynamics. The analytical results are compared with numerical simulations. Additional numerical simulations are presented for the minimum trapping amplitude and a fitted model is proposed. Results are discussed in detail.

WEPEA070	Space Charge Effects and Limitations in the Cern Proton Synchrotron	emittance, space-charge, proton, injection	2669
	R. Wasef, G. Arduini, H. Damerau, S.S. Gilardoni, S. Hancock, C. Hernalsteens, A. Huschauer, F. Schmidt CERN, Geneva, Switzerland G. Franchetti GSI, Darmstadt, Germany
	Space charge produces a large incoherent tune-spread which, in presence of betatronic resonances, could lead to beam losses and emittance growth. In the CERN Proton Synchrotron, at the current injection kinetic energy (1.4 GeV) and even at the future kinetic energy (2 GeV), space charge is one of the main limitations for high brightness beams and especially for the future High-Luminosity LHC beams. Several detailed studies and measurements have been carried out to improve the understanding of space charge limitations to determine the maximum acceptable tune spread and identify the most important resonances causing losses and emittance growth.

WEPEA072	Experimental Studies of Resonance Crossing in Linear Non-scaling FFAGs With the S-POD Plasma Trap	dipole, ion, focusing, betatron	2675
	S.L. Sheehy, D.J. Kelliher, S. Machida, C.R. Prior STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom K. Fukushima, K. Ito, K. Moriya, H. Okamoto HU/AdSM, Higashi-Hiroshima, Japan
	In a linear non-scaling FFAG the betatron tunes vary over a wide range during acceleration. This naturally leads to resonance crossing including first order integer resonances. The S-POD (Simulator for Particle Orbit Dynamics) plasma trap apparatus at Hiroshima University represents a physically equivalent system to a charged particle beam travelling in a strong focusing accelerator lattice. The S-POD system can be used as an ‘experimental simulation’ to investigate the effects of resonance crossing and its dependence on dipole errors, tune crossing speed and other factors. Recent developments and experiments are discussed.

WEPEA081	Local 3Qy Betatron Resonance Correction in the 2012 RHIC 250 GeV Run	sextupole, dynamic-aperture, proton, betatron	2696
	Y. Luo, W. Fischer, T. Roser, V. Schoefer, C.M. Zimmer BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In this article we performed numerical simulations to correct the local vertical third order betatron resonance 3Q_y in the interaction regions in the Yellow ring for the 2012 RHIC 250~GeV polarized proton run. Considering the main sources of skew sextupoles are located in the interaction regions, we used local bump methods to minimize their contributions to the global 3Q_y resonance driving term. Two kinds of correction orbit bumps are tested and the dynamic apertures with these correction strengths are calculated and compared.

WEPFI026	Design and Commissioning of the RF System of CYCIAE 14 Cyclotron	cyclotron, cavity, controls, low-level-rf	2759
	Z.G. Yin, B. Ji, Y. Lei, P.Z. Li, G.F. Song, C. Wang, T.J. Zhang, Z.L. Zhao CIAE, Beijing, People's Republic of China
	The RF system of CYCIAE-14 consists of a set of 20kW amplifier, two 1/4λ RF cavities connected in central region, the transmission line and a set of LLRF system. The LLRF system, based on DDS and DSP, has achieved the close-loop adjustment of accelerating voltage and the resonant frequency. The RF system design for CYCIAE-14 was started in 2010, and the fabrication of the major equipments was finished in 2011. The installation and commissioning was completed in early 2012, satisfying the design requirements. This article describes the design of the RF system, and summarizes the difficulties encountered in the process of manufacture, installation and commissioning. Some of the problems caused by the transmission line and the RF leakage are analyzed, followed by the measures taken to solve these problems.

WEPFI027	The Measurement of the Ferrite Rings for the Mass Production RF Cavity of CSNS RCS	cavity, impedance, LLRF, booster	2762
	H. Shi, W.L. Huang, B. Jiang, X. Li, W. Long, W.Y. Song, H. Sun, J.Y. Tang, C.L. Xie, C.L. Zhang, W. Zhang IHEP, Beijing, People's Republic of China
	The Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) will install 8 ferrite-loaded coaxial resonant cavities. The construction and measurement of prototype cavity have been finished. Based on the existing experiences, the small inner diameter (ID) rings T500/250/25-4M2 (mm) have been adopted for the mass production RF cavity, and the test results have shown that such rings can bear more RF magnetic flux density and have lower power loss. The characteristics of 60 small ID rings have been measured with two-ring test system, and we figured out that the rings have good consistence and the shunt impedance of all rings is above 100 Ω.

WEPFI054	Enlargement of Tuning Range in a Ferrite-tuned Cavity through Superposed Orthogonal and Parallel Magnetic Bias	cavity, factory, radiation	2812
	C. Vollinger, F. Caspers CERN, Geneva, Switzerland
	Conventional ferrite-tuned cavities operate either with bias fields that are orthogonal or parallel to the magnetic RF-field. For a cavity that tunes rapidly over an overall frequency range around 100-400 MHz with high Q, we use ferrite garnets exposed to an innovative new biasing method consisting of a superposition of perpendicular and parallel magnetic fields. This method leads to a significant enlargement of the high-Q cavity tuning range by defining an operation point close to the magnetic saturation and thus improving ferrite material behaviour. A further advantage of this technique is the fast tuning speed resulting from the fact that tuning is carried out either with pure parallel biasing, or together with a very small change of operating point from perpendicular bias. In this paper, several scaled test models of ferrite-filled resonators are shown; measurements on the set-ups are compared and discussed.

WEPFI059	C-band RF Pulse Compressor for SwissFEL	coupling, 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.

WEPFI062	Precise Cavity Tuning System of a Low Output-impedance Second-harmonic Cavity at ISIS	cavity, impedance, cathode, beam-loading	2836
	Y. Irie, S. Fukumoto, K. Muto, H. Nakanishi KEK, Ibaraki, Japan D.B. Allen, D. Bayley, N.E. Farthing, I.S.K. Gardner, R.J. Mathieson, A. Seville, J.W.G. Thomason STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom J.C. Dooling, D. Horan, R. Kustom, M.E. Middendorf ANL, Argonne, USA
	A very low output-impedance (~35ohms) second-harmonic cavity system is being developed for high intensity proton accelerators. The final amplifier is comprised of a grounded cathode scheme with a feedback loop from anode to grid. Due to the Miller effect, the grid voltage waveform is seriously distorted even if only a few percent of sub-harmonic or higher harmonic are mixed in the generator current. Such distortion is much enhanced by the beam loading. In order to eliminate the effect of this distortion upon the phase detector used to achieve precise cavity tuning, a swept bandpass filter was applied to the grid voltage at the phase detector input. Filter design details and the result of high power tests are reported.

WEPFI081	High Power Tests of Overmoded Waveguide for the ILC Klystron Cluster Scheme	klystron, linac, simulation, coupling	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.

WEPME023	Study of the Vibration of the AC Dipole and Magnetic Measurement Girder for CSNS/RCS	dipole, acceleration, damping, synchrotron	2980
	R.H. Liu, L. Kang, H. Qu, G.Y. Wang, H.J. Wang, J. S. Zhang IHEP, Beijing, People's Republic of China
	The dipole magnet of the China Spallation Neutron Source Rapid-cycling Synchrotron (RCS) will be operated at a 25Hz sinusoidal alternating current which causes severe vibration. The vibration will influence the long-term safety and reliable operation of the magnet. By taking the magnet and magnetic measurement girder as a specific model system, a method for analyzing and studying the dynamic characteristic of the system is put forward by combining theoretical calculation with experimental testing. And the ctive vibration of magnet is different with passive vibration which was causes by ground vibration, so a new isolator was designed to decrease the vibratory force and avoid the resonance phenomenon.

WEPME052	LLRF Characterisation of the Daresbury International Cryomodule	LLRF, cavity, cryomodule, SRF	3046
	L. Ma STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom P.A. Corlett, A.J. Moss STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The 2-cavity Superconducting RF (SRF) Linac cryomodule of the Accelerators and Lasers in Combined Experiments (ALICE) located at Daresbury Laboratory will be replaced by a new International ERL Cryomodule in early 2013. The improved 7-cell, 1.3 GHz SRF cavities will be characterised and compared with the original 9-cell cavities. Tests will be performed by driving the cavities by a VCO-PLL loop so that Q measurements, microphonics sensitivity and Lorentz force detuning can be analysed. A digital LLRF system using the LLRF4 board developed by Larry Doolittle has been developed at Daresbury Laboratory and will be installed on the upgraded cryomodule. This system is capable of controlled cavity filling to reduce waveguide reflection voltage, feedback/feed forward control and adaptive beam loading compensation. The new cryomodule will be evaluated with both the analog LLRF system and the digital LLRF system to allow for performance comparison. Cavity operation with high QL will also be tested to discover the feedback control limit as a function of inherent microphonics. This paper sets out to discuss the qualification process, testing and results of the upgraded cryomodule installation.

THYB101	Suppressing Transverse Beam Halo with Nonlinear Magnetic Fields	lattice, space-charge, damping, octupole	3099
	S.D. Webb, D.T. Abell, D.L. Bruhwiler, J.R. Cary Tech-X, Boulder, Colorado, USA V.V. Danilov ORNL, Oak Ridge, Tennessee, USA S. Nagaitsev, A. Valishev Fermilab, Batavia, USA
	Funding: This work was supported in part by the US Department of Energy's Office of Science, Office of High Energy Physics, under grant No. DE-SC0006247. Traditional space charge driven resonances, such as beam halo, arise due to the underlying linear nature of accelerator lattices. In this talk, we present initial results on a new class of intrinsically nonlinear lattices, which introduce a large tune spread naturally. The resulting nonlinear decoherence suppresses the onset of beam halo.
	Slides THYB101 [63.510 MB]

THPEA048	The FPGA-based Power Monitoring System for TPS Facility	monitoring, controls, factory, LabView	3252
	C.S. Chen, Z.-D. Tsai NSRRC, Hsinchu, Taiwan
	There are more and more non-linear electronic equipments such as inverters using in facility nowadays. These non-linear electronic equipments let us achieve energy saving, but induce other electrical pollution to the whole power grid in contrast. How to monitor the electrical noises from these non-linear equipments becomes an important issue. In this article, a set of power quality monitoring system based on FPGA and PAC has been built because of the programmability and fast processing speed. By using this monitoring system, any abnormality in power system and its spectrum will be recorded thoroughly. On the other hand, the maintainer could follow the trace of noise and then propose a suitable solution to eliminate the electrical interference too.

THPFI051	Radio-Frequency Multipacting as Quality Control of Coatings for e-Cloud Suppression	dipole, coupling, electron, 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.

THPFI052	Application of Atmospheric Plasma-sprayed Ferrite Layers for Particle Accelerators	plasma, vacuum, gun, electron	3406
	F. Caspers, M. Betz, S. Federmann, M. Taborelli CERN, Geneva, Switzerland K. K., C.A.M. Schulz Surface Engineering Institute, RWTH Aachen University, Aachen, Germany J.X. Wu IMP, Lanzhou, People's Republic of China
	A common problem in all kind of cavity like structures in particle accelerators is the occurrence of RF-resonances. Typically, ferrite plates attached to the walls of such structures like diagnostic devices, kickers or collimators, are used to dampen those undesired modes. However the heat transfer rate from these plates to the walls is rather limited. Brazing ferrite plates to the walls is not possible in most cases due to the different thermal expansion coefficients. To overcome those limitations, atmospheric plasma spraying techniques have been investigated. Ferrite layers with a thickness from 50 micron to about 300 micron can be deposited on metallic surfaces like stainless steel exhibiting good thermal contact and still reasonable absorption properties. In this paper the technological aspects of plasma deposition are discussed and results of specifically developed RF loss measurement procedures for such thin magnetically lossy layers on metal are presented. This kind of layers can also be applied for the production of high temperature RF power loads and related examples will be shown.

THPME008	Experimental Study of Magnetic Properties for Magnet Material in CYCIAE-100	focusing, cyclotron, factory, vacuum	3525
	J.Q. Zhong, T. Cui, M. Li, C. Wang, Z.H. Wang, J.J. Yang, T.J. Zhang CIAE, Beijing, People's Republic of China
	The magnetic property of magnet material is one of the key factors that influence the distribution of magnetic field in large scale cyclotrons, especially embody on the vertical focusing of field and the first harmonic field error in cyclotron. According to the requirements of the physical design of CYCIAE-100, we have studied the pivotal factors, which impact on the maximum permeability, coercivity and B-H curve of material of CYCIAE-100 magnet, including the cooling rate during magnetic annealing and residual stress. The study results will be shown in this paper.

THPWA019	THEORY RESEARCH ON APPLICATION OF CT TECHNOLOGY TO SHIELDED NUCLEAR MATERIAL DISCRIMINATION	electron, neutron, radiation, factory	3669
	Y. Zhang, H.B. Chen, Q. Gao, J. Shi TUB, Beijing, People's Republic of China
	Smuggling of nuclear material is a serious threat to security of international society. Formal research on nuclear material discrimination can fulfil customs inspection requirement. This paper designs a situation that nuclear material which is packaged and shielded by heavy metal need to be discriminated accurately on the condition that the object being detected cannot be dismantled. Calculation results prove nuclear material could be discriminated accurately while the ideal condition is fulfilled. If multi-energy X-ray source is used the discrimination accuracy is declined. However the accuracy could be improved while energy spectrum shaping technique is used.

THPWO030	Recent Progress in Beam Commissioning of J-PARC Linac	linac, DTL, simulation, radiation	3827
	M. Ikegami, Z. Fang, K. Futatsukawa, T. Miyao KEK, Ibaraki, Japan Y. Liu KEK/JAEA, Ibaraki-Ken, Japan T. Maruta J-PARC, KEK & JAEA, Ibaraki-ken, Japan A. Miura, J. Tamura JAEA/J-PARC, Tokai-mura, Japan
	The beam operation of J-PARC linac has been restored from the earthquake, and started to pursue higher beam power operation. We have also started to prepare for coming energy and intensity upgrade. In this paper, we review recent progress in beam commissioning of J-PARC linac with emphasis on the beam loss mitigation and preparation for the upgrade.

THPWO033	High Intensity Beam Trial of up to 540 kW in J-PARC RCS	injection, simulation, proton, linac	3836
	H. Hotchi, H. Harada, N. Hayashi, M. Kinsho, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Irie KEK, Ibaraki, Japan S. Kato Tohoku University, Graduate School of Science, Sendai, Japan
	Recently we have performed a high intensity beam trial of up to 540 kW. In this paper, beam intensity dependece and injection painting parameter dependence of beam loss, observed in this beam experiment, will be discussed with the corresponding numerical simulation results.

THPWO068	Resonance Frequency Control Characteristics of the 100-MeV Drift Tube Linac	controls, DTL, proton, linac	3912
	H.-J. Kwon, Y.-S. Cho, J.-H. Jang, H.S. Kim, K.T. Seol, Y.-G. Song KAERI, Daejon, Republic of Korea
	Funding: This work was supported by the Ministry of Science and Technology of the Korean Government. A 100-MeV, 20mA proton accelerator has been developed by KAERI (Korea Atomic Energy Institute). Total 11 DTL (Drift Tube Linac) tanks are used to accelerator the proton beam from 3-MeV to 100-MeV. A RCCS (Resonance frequency Control Cooling System) has been developed to control the resonance frequency of each DTL tank. The coolant for the drift tube and quadrupole magnets are supplied by the RCCS, whereas the wall coolant temperature maintains constant at 27 degree C by using the DI water supplied from the utility. In this paper, the resonance frequency control schemes are summarized and the control characteristics of the DTL tank by using the RCCS are discussed.

THPWO087	Measurement of Resonant Space Charge Effects in the J-PARC Linac	emittance, linac, simulation, space-charge	3966
	D.C. Plostinar STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom M. Ikegami J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Liu, T. Maruta KEK/JAEA, Ibaraki-Ken, Japan
	Traditionally, high intensity linac designs follow the “equipartitioning condition”, a strict control of the transverse and longitudinal tune ratios throughout the linac that ensures space-charge driven emittance exchange between the longitudinal and transverse planes is minimised. However, equipartitioning imposes strict rules on the linac design, thus limiting the design options and increasing the overall construction cost. More recently, practical tools have been developed that offer guidelines in designing non-equipartitioned linacs, by charting the stable regions in a tune ratio diagram (Hofmann’s Charts). While these stability diagrams have been backed by extensive multiparticle simulations and some experimental evidence, questions still remain regarding the practical consequences of crossing the resonances. In this paper preliminary results are presented from an experimental study conducted in the J-PARC linac, where for the first time we measured both the transverse and longitudinal emittance for different linac working points. A detailed analysis will be presented as well as a discussion on the wider implications of this experiment.

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MOPEA067

Ultra-low Emittance Upgrade Options for Third Generation Light Sources

emittance, lattice, dipole, dynamic-aperture

237

R. Bartolini
Diamond, Oxfordshire, United Kingdom
T. Pulampong
JAI, Oxford, United Kingdom

The increasing efforts in the synchrotron light sources community toward the design of a diffraction limited source at multi-keV photon energy have eventually stimulated the existing facilities to investigate possible upgrade paths to higher photon brightness and lower emittances to maintain their competitiveness within the users’ community. We present a possible option for upgrading 3rd generation light sources based on a rebiuld of the arcs with MBA cells, using diamond as an example. Emphasis is given to the AP desing issues with a view to minimal changes to the machine layout, contained cost and minimal downtime

MOPFI007

SIS-18 RF Knock-Out Optimization Studies

extraction, dipole, septum, synchrotron

297

M.M. Kirk, D. Ondreka, P.J. Spiller
GSI, Darmstadt, Germany

The extraction efficiency and spill temporal-structure of the SIS-18 heavy ion synchrotron are part of the upgrades to the GSI accelerator complex. Losses to the extraction septum can be minimised through implementation of the Hardt condition resulting however in a poorer quality of the spill microstructure at resolutions of a few microseconds due to lowering of the horizontal chromaticity from its 'natural' value. Ways to improve the extraction efficiency and spill microstructure are investigated with a tracking code. One possibility for improvement may be to use an alternative RF modulation applied to the knock-out exciter.

MOPFI020

Cold Test of the Coaxial Cavity for Thermionic Triode Type RF Gun

cavity, gun, electron, FEL

324

T. Konstantin, Y.W. Choi, T. Kii, R. Kinjo, K. Masuda, M. Mishima, K. Nagasaki, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, K. Yoshida, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A thermionic rf gun has several advantages as compared to photocathode gun. Such as low cost, high averaged current and simple operation. However a thermionic rf gun has a significant disadvantage in form of back bombardment effect. The KU-FEL facility is an oscillator type FEL, which uses a thermionic 4.5 cell S-band RF gun for electron beam generation. The back bombardment effect causes increasing current in macropulse, which limits the gain of the FEL. In order to mitigate the current increase we plan to modify thermionic rf gun to triode type rf gun. Therefore an additional rf cavity has been designed. This cavity has separate rf power supply with amplitude and phase control. By this means we can properly adjust the injection of electrons into the main gun body. According to simulations the triode type gun can reduce 80% of back streaming electron energy*. The cold tests of the first prototype have revealed deviation from designed values**. Based on the tests of the first prototype new prototype with integrated mechanism for resonance tuning has been designed and fabricated. In this work we report the cold test of the redesigned prototype of the coaxial rf cavity.
* K. Masuda et al. Proceedings of FEL 2006, BESSY Berlin.
** M. Takasaki et al. Proceedings of FEL 2010, Malbö

MOPFI045

Studying of Multipacting in Micro-pulse Electron Gun

electron, gun, simulation, cavity

383

L. Liao, W. Fang, Q. Gu, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

Depending on the complexity of multipacting phenomenon, more works are focused on the occurrence of multipacting in the micro-pulse electron gun. In this paper, the multipacting resonance condition is determined in a reentrant cavity model of the gun. The resonance parameters work as the input for VORPAL simulations in order to achieve a steady state saturation in the cavity. The simulation results showed that the gun can give rise to electrons beam with high currents and short pulses.

MOPFI046

Transverse RF Kicker Excitation and Longitudinal RF Noise Diffusion for Slow Extraction from SAPT

extraction, kicker, simulation, synchrotron

386

L. Ouyang, M. Gu, D.M. Li, Q. Yuan, M.Z. Zhang
SINAP, Shanghai, People's Republic of China

Two key techniques used in the slow extraction from synchrotron accelerator: longitudinal RF stochastic noise acceleration, and transverse RF knock out excitation have been studied in this paper. Detailed comparison have revealed the potentials and limits of both methods. For the longitudinal RF stochastic acceleration excitation, the focus has been the phase space compression of particles, which makes the them to hasten around the RF bucket of the cavity, thus to lower the senstivity to ripple. For the transverse RF knock out excitation, the emphasis have been optimal schemes of amplitude modulation and frequency modulation of the RF singals. The optimizations are also used to lower the senstivity of the beam to the ripple and to enhance the uniformity of the extracted beam.

MOPME005

Goubau Line and Beam Characterization of TURBO-ICT for SwissFEL

instrumentation, FEL, electron, laser

476

S. Artinian, J.F. Bergoz, F. Stulle
BERGOZ Instrumentation, Saint Genis Pouilly, France
P. Pollet, V. Schlott
PSI, Villigen PSI, Switzerland

SwissFEL will be able to operate with electron bunch doublets 28ns apart. Each of the bunches carries 10pC to 200pC of charge with bunch lengths of a few femto-seconds. For charge calibration of the FEL photon pulses, a measurement accuracy of 1% is desired. The Turbo-ICT accomplishes these requirements with negligible beam position and bunch length dependence. It is insensitive to dark current and features high immunity to background noise. We characterize the Turbo-ICT performance on a Goubau line, also known as single-wire transmission line. The Goubau line utilizes electromagnetic fields with frequencies up to many GHz. It allows accurate bench testing including beam position and bunch length dependence. The results are compared to beam measurements performed at the SwissFEL Injector Test Facility (SITF).

MOPWA071

A Comparison of Electron Cloud Density Measurements at CesrTA

electron, simulation, positron, pick-up

843

J.P. Sikora, J.A. Crittenden, D.O. Duggins, Y. Li, X. Liu
CLASSE, Ithaca, New York, USA
S. De Santis
LBNL, Berkeley, California, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
Several techniques have been employed to measure the electron cloud (EC) density in accelerators. These include Time Resolved Retarding Field Analyzers (TR-RFA) and Shielded Pickups (SPU) that measure the flux of cloud electrons onto the beam-pipe wall, as well as TE wave resonance techniques that measure the EC density in a region within the volume of the beam-pipe. We have made measurements to test the EC mitigation properties of different surface coatings and geometries, often with more than one technique used in the same test chamber. We present a comparison of bare aluminum chambers with those having a TiN coating, as well as the effect of beam conditioning. In addition, we will compare the results of the different measurement techniques used in the same chamber. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CesrTA) having positron or electron beam energies ranging from 2 GeV to 5 GeV.

MOPWA085

Spin Dynamics Simulations and Horizontal Intrinsic Resonance Studies in the AGS using the Zgoubi Code

polarization, simulation, acceleration, extraction

870

Y. Dutheil, L. A. Ahrens, H. Huang, F. Méot, V.H. Ranjbar, T. Roser, V. Schoefer, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A critical point for the polarized proton program of the RHIC is the polarization transmission through the AGS acceleration cycle. Recent developments in the Zgoubi model of the AGS allow multi-particle tracking with realistic beam and machine conditions on a large scale computing system. This gives the opportunity to simulate the influence of many beam and machine conditions on the polarization transmission and leads to a better understanding of the depolarization processes, for instance the horizontal intrinsic resonances, that cannot be accurately explored by the conventional simulation approaches or by the experiments with beam. This paper introduces the developments realized on the Zgoubi code to run these simulations and shows some of the latest results.

MOPWO005

Simulating Spin Dynamics and Depolarization using POLE

synchrotron, simulation, polarization, synchrotron-radiation

891

J.F. Schmidt, O. Boldt, F. Frommberger, W. Hillert
ELSA, Bonn, Germany

Funding: BMBF
The spin dynamics in circular accelerators with fast energy ramps, or short storage times of up to some seconds, can be investigated with spin tracking appropriately. Additionally, the spin motion of lepton beams is affected significantly by synchrotron radiation. Hence, spin dynamics simulations require spin tracking with a large number of particles to compute the beam polarization and thus take considerably long computing times. Therefore, high efficiency is crucial to perform systematic polarization studies. The new simulation tool POLE provides the ability to balance accuracy against computing time. To that end, adjustable approximations of magnetic fields and synchrotron radiation are implemented. POLE is accessible for a wide range of lepton storage rings because it uses the common MAD-X lattice files and the corresponding particle tracking results.

MOPWO006

Eigenmode Computation for the GSI SIS18 Ferrite Cavity

cavity, heavy-ion, ion, synchrotron

894

K. Klopfer, W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Supported by GSI
At the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt the heavy-ion synchrotron SIS18 is operated to further accelerate stable nuclei of elements with different atomic numbers. Two ferrite-loaded cavity resonators are installed within this ring. During the acceleration phase their resonance frequency has to be adjusted to the revolution frequency of the heavy-ions to reflect their increasing speed. To this end, dedicated biased ferrite-ring cores are installed inside the cavities for a broad frequency tuning. By properly choosing a suited bias current, the differential permeability of the ferrite material is modified, which finally enables to adjust the eigenfrequency of the resonator system. Consequently, the actual resonance frequency strongly depends on the magnetic properties of the ferrites. The goal of the current study is to numerically determine the lowest eigensolutions of the GSI SIS18 ferrite-loaded cavity. For this purpose, a new solver based on the Finite Integration Technique has been developed.

MOPWO007

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

dipole, cavity, electromagnetic-fields, impedance

897

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

Funding: Work supported by BMBF under contract 05H12RD5
The acceleration with superconducting radio frequency cavities requires dedicated couplers to transfer energy from the radio frequency source to the beam. Simultaneously, higher order mode couplers are installed to effectively suppress parasitic modes. Therefore, the numerical eigenmode analysis based on real-valued variables is no longer suitable to describe the dissipative acceleration structure. At the Computational Electromagnetics Laboratory (TEMF) a robust parallel eigenmode solver to calculate the eigenmodes in the lossy acceleration structure is available. This eigenmode solver is based on complex-valued finite element analysis and utilizes basis functions up to the second order on curved tetrahedral elements to enable the high precision elliptical cavity simulations. The eigenmode solver has been applied to the TESLA 1.3 GHz accelerating cavity to determine the resonance frequency, the quality factor and the corresponding field distribution for all 192 eigenmodes up to the 5th dipole passband (3.12 GHz).

MOPWO026

Investigation of Numerical Precision Issues of Long Term Single Particle Tracking

simulation, dynamic-aperture, beam-beam-effects, HOM

942

E. McIntosh, R. De Maria, M. Giovannozzi
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Long term single particle simplectic tracking is one of the most reliable tool to study the dynamic aperture of the circular accelerators. The present computational performance allows to explore the long term behaviour for an extended number of turns. It is well known that for instance single precision floating point arithmetic introduces too much numerical noise even after a moderate number of turns. In this paper we explore the artefacts of the double precision arithmetic that may be visible when the number of turns is in the order of 10⁶, 10⁷.

MOPWO044

Numerical Simulations of a Hollow Electron Lens as a Scraping Device for the LHC

electron, simulation, collimation, proton

993

V. Previtali, G. Stancari, A. Valishev
Fermilab, Batavia, USA
S. Redaelli
CERN, Geneva, Switzerland

Funding: Fermilab is operated by Fermi Research Alliance, LLC, Contract No.DE-AC02-07CH11359 with the United States Dep. of Energy. This work was partially supported by US LHC Accelerator Research Program(LARP)
The use of hollow electron beam lens for scraping high energy proton beams has been extensively tested at Fermilab's Tevatron collider. In order to evaluate a possible application of a similar a device in the LHC, a dedicated new routine has been implemented in the standard 6D tracking code used at CERN for the design of the LHC collimation system. The effects of a finite length cylinder of electrons encompassing the main proton beam and traveling in the opposite direction is described in the routine. Realistic electron distributions, including measured radial imperfections, have been included in the model. Various operating modes have been simulated for the 7 TeV machine operation with sextupoles and octupoles included. The loss rate caused by the electron lens has been studied through an extended simulation campaign; the obtained halo removal rates for the different electron lens operating modes are presented.

MOPWO050

Comparison of LHC Beam Loss Maps using the Transverse Damper Blow up and Tune Resonance Crossing Methods

collimation, injection, betatron, background

1008

V. Moens, R. Bruce, S. Redaelli, B. Salvachua, G. Valentino
CERN, Geneva, Switzerland
V. Moens
EPFL, Lausanne, Switzerland
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The LHC collimator settings are qualified regularly via beam loss maps. In this procedure, the beam is artificially excited to create abnormal loss rates. The transverse damper blow up and tune resonance crossing methods are used to increase the betatron amplitude of particles and verify the efficiency of the collimation cleaning and the collimator hierarchy. This paper presents a quantitative comparison of the methods, based on measurements done at different phases of the LHC machine cycle. The analysis is done using Beam Loss Monitor (BLM) with integration times of 1.3 s and 80 ms. The use of the faster BLM data to study the time evolution of the losses in IR3 and IR7 during off-momentum loss maps is also presented.

TUYB103

Status and Plans for the Polarized Hadron Collider at RHIC

polarization, proton, acceleration, luminosity

1106

M. Bai, L. A. Ahrens, E.C. Aschenauer, G. Atoian, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, O. Eyser, W. Fischer, C.J. Gardner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, A.I. Kirleis, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, V. Schoefer, F. Severino, T.C. Shrey, D. Smirnov, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
As the world’s only high energy polarized proton collider, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) has been providing collisions of polarized proton beams at beam energy from 100~GeV to 255~GeV for the past decade to explore the proton spin structure as well as other spin dependent measurements. With the help of two Siberian Snakes per accelerator plus outstanding beam control, beam polarization is preserved up to 100~GeV. About 10% polarization loss has been observed during the acceleration between 100~GeV and 255~GeV due to several strong depolarizing resonances. Moderate polarization loss was also observed during a typical 8 hour physics store. This presentation will overview the achieved performance of RHIC, both polarization as well as luminosity. The plan for providing high energy polarized He-3 collisions at RHIC will also be covered.
This work is on behalf of RHIC team.

Slides TUYB103 [12.854 MB]

TUPEA012

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

neutron, coupling, 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.

TUPEA029

Theory Calculation of PASER in Gas Mixture Active Medium

electron, laser, wakefield, plasma

1211

X.F. Tian, C.-F. Wu
USTC/NSRL, Hefei, Anhui, People's Republic of China

In the PASER (particle acceleration by stimulated emission of radiation), the energy stored in an active medium transferred directly to the electron beam passing through in discrete amounts by emitting a photon when the bounded electron returns from upper to lower energy state. In this paper, the wake-field generated by a bunch of electrons traversing in an active medium has been discussed. The calculations of the development of amplitude for gas mixture active medium about CO2 and ArF were made respectively. The results show that the gradient can reach around 1GeV/m. In addition, the electron energy gain occurring as a train of electron micro-bunches traversing in gas mixture was analyzed by a two dimension model. The train of micro-bunches can obviously gain energy from the active medium and the energy exchange is linearly proportional to the interaction length d. The influence of the bunch figure and other quantities on the energy exchange occurring as a train of electron micro-bunches traversing CO2 gas mixture were investigated when the interaction length is 0.5m. The results illustrate that maximum electron energy gain can be obtained by the train of micro-bunches with optimized parameters.

TUPEA056

Concept of Dielectric Wakefield Accelerator Driven by a Long Sequence of Electron Bunches

wakefield, electron, acceleration, injection

1259

I.N. Onishchenko, V. Kiselev, A. Linnik, G.V. Sotnikov
NSC/KIPT, Kharkov, Ukraine

Funding: This study is supported by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522)
The scheme of a two-beam accelerator type is considered that is based on wakefield excitation in rectangular dielectric resonator by a sequence of electron bunches with the aim to enhance wakefield intensity due to multi-bunch coherent excitation, multi-mode summation, and wakefield accumulation in resonator. The sequence of bunches can be divided into exciting and accelerated parts in any proportion by means at the proper detuning of bunch repetition frequency relative to the frequency of principle eigen mode of the resonator. A train of 6000 electron bunches, each of energy 4.5МeV, charge 0.16nC, duration 60psec, diameter 1.0cm, and angular spread 0.05 mrad is produced with the linear resonant accelerator. Bunch repetition frequency is 2805 MHz and can be varied within 2MHz by changing master oscillator frequency. Bunches are injected into copper rectangular waveguide of cross-section 8.5x18.0cm² and length 75cm along wide sides of which Teflon plates are placed. The plate thickness is chosen 1.67cm so that the frequency of excited eigen mode coincides with bunch repetition frequency.

TUPEA066

Metamaterial-based Accelerating, Bending and Focusing Structures

focusing, electron, quadrupole, vacuum

1286

I. McGregor
The University of Liverpool, Liverpool, United Kingdom
K.M. Hock
Cockcroft Institute, Warrington, Cheshire, United Kingdom

We report on the progress of our research into metamaterial-based accelerating, bending and focusing structures at the Cockcroft Institute. The effort during the last year has been directed towards designing and investigating practical RF structures that are suitable for industrial and medical applications. We have shown that, by introducing structures based on metamaterial resonators, RF accelerating structures can be made more compact and higher gradient. This year, we will concentrate on focusing and bending structures.

TUPFI063

Electromagnetic Coupling between High Intensity LHC Beams and the Synchrotron Radiation Monitor Light Extraction System

simulation, impedance, extraction, synchrotron

1493

F. Roncarolo, W. Andreazza, A. Bertarelli, E. Bravin, F. Caspers, M. Garlaschè, A. Goldblatt, J-J. Gras, O.R. Jones, T. Lefèvre, E. Métral, A.A. Nosych, B. Salvant, G. Trad, R. Veness, C. Vollinger, M. Wendt
CERN, Geneva, Switzerland

The CERN LHC is equipped with two Synchrotron Radiation Monitor systems used to characterise transverse and longitudinal beam distributions. Since the end of the 2011 LHC run the light extraction system, based on a retractable mirror, has suffered deformation and mechanical failure that is correlated to the increase in beam intensity. Temperature probes have associated these observations to a strong heating of the mirror support with a dependence on the longitudinal bunch length and shape, indicating the origin as electromagnetic coupling between the beam and the structure. This paper combines all this information with the aim of characterising and improving the system in view of its upgrade during the current LHC shutdown. Beam-based observations are presented along with electromagnetic and thermomechanical simulations and complemented by laboratory measurements, including the study of the RF properties of different mirror bulk and coating materials.

TUPFI068

High Power Tests of Alumina in High Pressure RF Cavities for Muon Ionization Cooling Channel

cavity, pick-up, collider, klystron

1508

L.M. Nash
University of Chicago, Chicago, Illinois, USA
G. Flanagan, R.P. Johnson, F. Marhauser, J.H. Nipper
Muons. Inc., USA
M.A. Leonova, A. Moretti, M. Popovic, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA
Y. Torun
IIT, Chicago, Illinois, USA

It is important to make a compact muon ionization cooling channel to increase the cooling efficiency (muon survival rate, cooling decrement, etc). A proposed scheme to reduce the radial size of RF cavities at a given resonance frequency is to insert a dielectric material into the RF cavity. In vacuum cavities, however, dielectric materials are extremely susceptible to breakdown in high power conditions. High-pressure hydrogen gas has been shown to inhibit breakdown events in RF cavities in strong magnetic fields. An experiment has been designed to test surface breakdown of alumina in RF cavities. A structure has been designed to maximize the parallel field parallel to the surface while bringing the cavity into a desired frequency range (800-810MHz). Alumina is tested in this configuration under high power conditions. The experimental result will be shown in this presentation.

TUPFI083

Simulation Study of Head-on Beam-beam Compensation with Realistic RHIC Lattices

lattice, dynamic-aperture, proton, simulation

1541

Y. Luo, M. Bai, W. Fischer, C. Montag, V.H. Ranjbar, S. Tepikian
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We performed numerical simulations to study the effects of head-on beam-beam compensation with the realistic RHIC lattices. To better cancel the beam-beam resonance driving terms during half beam-beam compensation operation, the betatron phase advances between the interaction point IP8 and the center of the electron lens should be multiples of pi. for this purpose two shunt power supplies were added to the main quadrupole circuit buses in the arc between them. For the realistic beam-beam compensation lattices, the integer tunes are (27, 29) for the Blue ring and (29, 30) for the Yellow ring. The betatron phase advances between IP8 and the e-lens are (8pi,11pi) in the Blue ring and (11pi, 9pi) in the Yellow ring. Recent simulation results will be presented.

TUPFI084

RHIC Polarized Proton Operation for 2013

emittance, lattice, polarization, injection

1544

V.H. Ranjbar, L. A. Ahrens, E.C. Aschenauer, M. Bai, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, W. Fischer, C.J. Gardner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, A.I. Kirleis, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V. Ptitsyn, G. Robert-Demolaize, T. Roser, W.B. Schmidke, V. Schoefer, F. Severino, T.C. Shrey, D. Smirnov, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
BNL, Upton, Long Island, New York, USA
O. Eyser
UCR, Riverside, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The 2013 operation of the Relativistic Heavy Ion Collider (RHIC) marks the second year of running under the RHIC II era. Additionally this year saw the implementation of several important upgrades designed to push the intensity frontier. Two new E-lenses have been installed, along with a new lattice designed for the E-lens operation. A new polarized proton source which generates about factor of 2 more intensity was commissioned as well as a host of RF upgrades from a new longitudinal damper, Landau cavity in RHIC to a new low level RF and new harmonic structure for the AGS. We present an overview of the challenges and results from this years run.

TUPME001

Effect of Self-consistency on Space Charge Induced Beam Loss

simulation, space-charge, emittance, controls

1556

G. Franchetti
GSI, Darmstadt, Germany

In long term storage space charge driven incoherent effect may lead to a slow beam diffusion that causes emittance growth and beam loss. However, when beam loss are relevant the full mechanism cannot be understood only driven by an incoherent effect. In this proceeding the issue of the self-consistency is discussed, and its impact presented for simplified examples and for the SIS100.

TUPME004

Spin Tracking at the International Linear Collider

dipole, polarization, positron, damping

1565

V.S. Kovalenko, G.A. Moortgat-Pick, A. Ushakov
University of Hamburg, Hamburg, Germany
S. Riemann
DESY Zeuthen, Zeuthen, Germany
M. Vogt
DESY, Hamburg, Germany
A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Optimization", contract number 19XL7Ic4
In the baseline design for the International Linear collider an helical undulator-based positron source has been chosen that can provide positrons with a polarization of 60% as an upgrade option motivated by physics reasons. But even the baseline configuration would already provide about 30%. In order to match the high precision requirements from physics and to optimize the physics outcome one has to control systematic uncertainties to a very high level. Therefore it is needed to run both beams polarized but provide also an unpolarized set-up for control reasons. In our study we present results on precise spin tracking and propose also an minimal machine set-up to run in an unpolarized mode within the baseline design.

TUPME009

Measurement and Vibration Studies on the Final Focus Doublet at DAΦNE and new collider Implications

damping, collider, luminosity, factory

1580

S. Tomassini
INFN/LNF, Frascati (Roma), Italy

Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu-CARD, grant agreement no. 227579.
A Super Flavour Factory, to be built in the Tor Vergata University campus near Frascati, Italy, will have nano-beams in order to reach the design luminosity. The knowledge and compensation of the vibrations induced on the beams by the anthropic noise is then fundamental. The DAΦNE Phi-factory at LNF, Frascati, was upgraded in the second half of 2007 in order to implement the large Piwinski angle and crab waist collision scheme and in 2010 the KLOE experiment was rolled in for a new data taking and physic program. A measurement campaign has been performed on DAΦNE to find out the actual vibration sensitivity of the final focus doublets. Vibration measurements were performed on the Final Focus doublet because of luminosity losses and photon beam lines instability evidences. Results and stabilization technique to mitigate the effects of the ground motion induced by the “cultural noise” are presented. Implications on the design and stabilization of a Flavour Factory Final Focus doublets will be discussed.

TUPME012

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

optics, space-charge, sextupole, coupling

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.

TUPME016

Crosstalk Between Beam-beam Interaction and Lattice Nonlinearities in the SuperKEKB

simulation, luminosity, lattice, betatron

1601

D. Zhou, K. Ohmi, Y. Ohnishi, K. Oide, H. Sugimoto
KEK, Ibaraki, Japan

Momentum-dependent lattice nonlinearities have been proven to be important for the luminosity performance in the KEKB B-factory. As an upgrade of KEKB, the SuperKEKB adopts nano-beam scheme, in which the colliding beams are squeezed to extremely small sizes at the interaction point. Consequently, the lattice nonlinearities in SuperKEKB become more stronger than in KEKB. Using two codes, SAD and BBWS, we did various simulations to study the crosstalk between beam-beam interaction and lattice nonlinearities. It is found that lattice nonlinearities can cause remarkable luminosity loss in the SuperKEKB.

TUPME033

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

impedance, kicker, coupling, injection

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.

TUPME060

Tune Studies with Beam-Beam Effects in LHC

emittance, simulation, luminosity, collider

1703

S. Paret, J. Qiang
LBNL, Berkeley, California, USA
R. Alemany-Fernandez, X. Buffat, R. Calaga, K. Cornelis, M. Fitterer, R. Giachino, W. Herr, A. Macpherson, G. Papotti, T. Pieloni, S. Redaelli, F. Roncarolo, M. Schaumann, R. Suykerbuyk, G. Trad
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231.
In high brightness colliders, the tune spread due to the collisions has a significant impact on the quality of the beams. The impact of the working point on emittance growth and beam lifetime has been observed in beam experiments in LHC. Strong-strong beam-beam simulations that were accomplished to better understand such observations are shown. Compared to experiments, wide ranged parameter scans can be done easily. Tune footprints and scans of the emittance growth obtained from simulations are discussed. Three cases are considered: Very high intensity, moderate intensity and collisions with separated beams.

TUPME061

Emittance Growth with Crab Cavity and Damper Noise in LHC

emittance, simulation, pick-up, damping

1706

S. Paret, J. Qiang
LBNL, Berkeley, California, USA

Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231.
Strong-strong beam-beam simulations are employed to investigate the noise sensitivity of the emittance in the future High Luminosity (HL)-LHC. Noise in the accelerator causes fluctuations of the bunch centroids at the interaction points (IPs) which cause emittance growth for large beam-beam parameters. Two noise sources are examined: Crab cavities and the transverse damper. The damper noise is adjusted to bring simulations in agreement with an emittance measurement in a past LHC run. Results from simulations with HL-LHC beam parameters using different noise levels, damper gains and working points are discussed.

TUPME064

Envelope Perturbations in a Space-Charge-Dominated Electron Beam

simulation, space-charge, quadrupole, lattice

1712

W.D. Stem, B.L. Beaudoin, I. Haber, R.A. Kishek, T.W. Koeth
UMD, College Park, Maryland, USA

Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
Linear perturbation analysis of the RMS envelope equations predicts a frequency splitting of the transverse envelope resonances with the onset of space charge. These resonances are a potential source of beam degradation for space-charge-dominated particle accelerators and storage rings. We use WARP for both envelope code integration and particle-in-cell (PIC) simulations to predict the behavior of these resonances for an existing alternating gradient lattice storage ring. The focus of these simulations is tailored toward examining physics that is scalable to future high-intensity accelerators. This paper provides detailed simulation results and a design for an experimental demonstration at the University of Maryland Electron Ring (UMER), a high intensity 10 keV electron storage ring.

TUPWA007

Method and Results of Systematic Beam Matching to a Periodic DTL

emittance, DTL, focusing, quadrupole

1733

L. Groening, W.A. Barth, P. Forck, I. Hofmann, S.G. Yaramyshev
GSI, Darmstadt, Germany
D. Jeon
IBS, Daejeon, Republic of Korea

Systematic investigations on high current 3d-beam matching to a periodic Alvarez-type DTL are reported. Twiss parameters at the entrance of a matching section to the periodic structure were concluded from transverse and longitudinal measurements. Periodic solutions in 3d were calculated including space charge using the measured rms emittances. The matching was performed by rms beam size tracking and employing a numerical routine to set the matching section, which comprises five quadrupoles and two bunchers. Matching allowed for significant emittance growth reduction and for verification of non-linear beam dynamics effects along the DTL.

TUPWA010

A Trial to Reduce the Kicker Impedance of 3-GeV RCS in J-PARC

kicker, impedance, acceleration, status

1742

Y. Shobuda, N. Hayashi, T. Takayanagi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Irie
KEK, Ibaraki, Japan
T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

At 3GeV RCS in J-PARC, the kicker impedance has been considered to be the dominant source to cause the beam instability. Recently, experimental studies demonstrate that the beam instability is suppressed by reducing the kicker impedance. In this report, a trial to reduce the kicker impedance is reported.

TUPWA011

Investigation of Emittance Growth in a Small PET Cyclotron CYCIAE-14

cyclotron, emittance, extraction, simulation

1745

M. Li, Shizhong. An, T.J. Zhang
CIAE, Beijing, People's Republic of China

In order to satisfy the rapidly increased domestic needs for PET in China, a small medical cyclotron named CYCIAE-14 is designed and constructed in CIAE ( China Institute of Atomic Energy ) . As the beam intensity in CYCIAE-14 is high, the beam emittance should be controlled strictly in order to reduce the beam loss in the cyclotron. Precessional mixing and resonance crossing are the two main factors leading to emittance growth in the cyclotron with stripping extraction. In this paper, the physical mechanism of precessional mixing in a stripping extraction cyclotron is investigated. After that, the maximum allowable field errors in CYCIAE-14 are derived using the Hamiltonian formalism and numerical simulation, which provides a reference for the cyclotron design and field shimming.

TUPWA012

The Influence of the Magnetic Field Errors in CYCIAE-100 Cyclotron

emittance, cyclotron, simulation, TRIUMF

1748

H.J. Yao, M. Li, T.J. Zhang, J.Q. Zhong
CIAE, Beijing, People's Republic of China

The main magnet size of CYCIAE-100 is 2.31 m in height and 6.16 m in diameter and the outer radius of the sector is 2.0 m, and the total iron weight is about 415t. The magnetic filed can not be absolutely ideal because of imperfections during manufacturing and installation of this big magnet. Therefore the influence of the magnetic field errors on the beam behavior should be studied to provide the reference for magnet mapping and shimming. Magnetic field errors in a cyclotron will excite coherent oscillations through displacing the center of orbit or distorting the transverse phase space. This effect is especially important in the CYCIAE-100 cyclotron because there are a number of different turns in the extracted beam. The tolerances for the magnetic field errors are given in this paper based on analytic calculations and numerical simulations. The resonances vr=1, 2vr=2 driven by the 1st, 2nd harmonic magnetic field are considered, which will result in the radial emittance growth .Besides that, the resonances cause the vertical emittance growth are considered. The maximum allowable field errors for CYCIAE-100 are presented in this paper.

TUPWA034

On the Choice of Linac Parameters for Minimal Beam Losses

space-charge, linac, emittance, beam-losses

1787

M. Eshraqi
ESS, Lund, Sweden
J.-M. Lagniel
GANIL, Caen, France

In high intensity linear accelerators, the tune spreads induced by the space-charge forces in the radial and longitudinal planes are key parameters for halo formation and beam losses. For matched beams they are the parameters governing the number of resonances (including coupling resonances) which affect the beam and determine the respective sizes of the stable and halo areas in phase space. The number and strength of the resonances excited in mismatched beams leading to even higher amplitude halos are also directly linked to the tune spreads. In this paper, the equations making the link between the basic linac parameters (rf frequency, zero-current phase advances, beam intensity and emittances) and the tune spreads are given. A first analysis of the way these linac parameters can be chosen to minimize the tune spreads is presented. The parameters of ESS linac are used for this study.

TUPWA039

Identification of the SPS Impedance at 1.4 GHz

impedance, optics, simulation, bunching

1793

T. Argyropoulos, T. Bohl, H. Damerau, J. Esteban Müller, E.N. Shaposhnikova, H. Timko
CERN, Geneva, Switzerland

In the SPS spectrum measurements of very long single bunches were used in the past to identify sources of longitudinal microwave instability. Shielding of the identified objects significantly improved the beam stability. However, longitudinal instabilities are still one of the limitations for high intensity LHC beams in the SPS. Recently the same measurement technique was used again, revealing a strong high frequency resonance. During the slow de-bunching with the RF switched off, the presence of different resonant impedances leads to a line density modulation at the resonant frequencies. Longitudinal profiles of bunches of various intensities were acquired. For sufficiently high intensities their spectra show a fast growing and strong modulation at 1.4 GHz. Measurements using two transverse optics with different transition energy are compared. Reproducing the measurements with numerical simulations, including the known SPS longitudinal impedances, allowed the parameter range of this unknown source to be determined. Possible candidates as impedance sources in the SPS ring are investigated.

TUPWA042

Lessons Learned and Mitigation Measures for the CERN LHC Equipment with RF Fingers

impedance, vacuum, damping, simulation

1802

E. Métral, O. Aberle, R.W. Aßmann, V. Baglin, M.J. Barnes, O.E. Berrig, A. Bertarelli, G. Bregliozzi, S. Calatroni, F. Carra, F. Caspers, H.A. Day, M. Ferro-Luzzi, M.A. Gallilee, C. Garion, M. Garlaschè, A. Grudiev, J.M. Jimenez, O.R. Jones, O. Kononenko, R. Losito, J.L. Nougaret, V. Parma, S. Redaelli, B. Salvant, P.M. Strubin, R. Veness, C. Vollinger, W.J.M. Weterings
CERN, Geneva, Switzerland

Beam-induced RF heating has been observed in several LHC components when the bunch/beam intensity was increased and/or the bunch length reduced. In particular eight bellows, out of the ten double-bellows modules present in the machine in 2011, were found with the spring, which should keep the RF fingers in good electrical contact with the central insert, broken. Following these observations, the designs of all the components of the LHC equipped with RF fingers have been reviewed. The lessons learnt and mitigation measures are presented in this paper.

TUPWA043

Impedance Studies for VMTSA Module of LHC Equipped with RF Fingers

impedance, simulation, factory

1805

O. Kononenko, F. Caspers, A. Grudiev, E. Métral, B. Salvant
CERN, Geneva, Switzerland

During 2011 run of LHC it was found that beam-induced heating causes many issues for accelerator components. Particularly some of the double-bellow modules, called VMTSA modules, were found to have deformed RF fingers and a broken spring which ensured good contact between them and a central insert. Impedance studies have been performed for different types of nonconformities and benchmarked against measurements. It was found that even a small gap between the fingers and a central insert could be fatal for the VMTSA operation. Results of this study were an input for the further thermal analysis.

TUPWA062

Dependence of Beam Instabilities Caused by Electron Clouds at CesrTA on Variations in Bunch Spacing and Chromaticity

electron, damping, dipole, positron

1844

M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, R.E. Meller, M.A. Palmer, G. Ramirez, N.T. Rider, K.G. Sonnad, H.A. Williams
CLASSE, Ithaca, New York, USA
R.F. Campbell, R. Holtzapple, M. Randazzo
CalPoly, San Luis Obispo, California, USA
J.W. Flanagan
KEK, Ibaraki, Japan

Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867 and the Lepton Collider R&D Coop Agreement: NSF Award PHY-1002467
Experiments have been performed at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) to probe the interaction of the electron cloud with a 2.1 Gev stored positron beam. The purpose of these experiments was to characterize the dependence of beam–electron cloud interactions on the bunch spacing and the vertical chromaticity. These experiments were performed on a 30-bunch positron train, at a fixed current of 0.75mA/bunch. The bunch spacing was varied between 4 and 28 ns at three different vertical chromaticity settings. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated Beam Position Monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches within these different trains.

TUPWA067

Beam Emittance Growth Effects in High-intensity RFQ

rfq, emittance, linac, space-charge

1859

Y.K. Batygin, R.W. Garnett, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

Beam dynamics in an RFQ are strongly affected by coupling between transverse and longitudinal particle oscillations. The adiabatic process of high-intensity bunched beam formation results in equipartitioning in the RFQ, which determines the longitudinal beam emittance. Avoiding parametric resonances is an important design criterion to prevent significant emittance growth of the beam. Manufacturing errors can result in beam emittance growth and reduction of beam transmission. This paper will present the results of a study where analytical and numerical evaluations were performed to determine the effect of the aforementioned factors on beam quality in a high-current RFQ.

TUPWA071

Studies of Resistive Wall Heating at JLAB FEL

impedance, FEL, wiggler, electron

1868

R. Li, S.V. Benson
JLAB, Newport News, Virginia, USA

Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
When the JLAB FEL is under CW operation, it had been observed that temperature rises over the wiggler vacuum chamber, presumably as the result of the power deposition on the resistive wall of the wiggler chamber. Previous analyses have been done on the resistive wall impedance for various cases, such as DC, AC, and anomalous skin effects*. Here we report an investigation on the beam kinetic energy losses for each of these cases. This study includes the non-ultrarelativistic effect on resistive wall loss, for both round pipe and parallel plates. We will present the comparison of our results with the measured data obtained during CW operation of the JLAB FEL. Other possible factors contributing to the measured heating will also be discussed.
* K. Bane and G. Stupakov, SLAC-PUB-10707, 2004.

WEOAB102

CSR-driven Longitudinal Single Bunch Instability Thresholds

impedance, synchrotron, damping, electron

2041

P. Kuske
BESSY GmbH, Berlin, Germany

According to Bane, et al.* threshold currents should follow a quite simple scaling law. More detailed theoretical results for the underlying shielded CSR-interaction have been performed for BESSY-II and the MLS and will be presented in comparison with observations at these storage rings. It is found that there are parameter regions where the instability is weak and thus thresholds depend on damping time and synchrotron tune. Theoretical findings are in surprisingly good agreement with most of the observed instability features.
* K.L. Bane, et al., Phys. Rev. ST-AB 13, 104402 (2010)

Slides WEOAB102 [0.779 MB]

WEPWA047

Longitudinal Stability of Multiturn ERL with Split Accelerating Structure

linac, electron, simulation, cavity

2226

Ya.V. Getmanov, O.A. Shevchenko, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia
T. Atkinson
HZB, Berlin, Germany
N. Vinokurov
KAERI, Daejon, Republic of Korea

Some modern projects of the new generation light sources use the conception of multipass energy recovery linac with split (CEBAF-like) accelerating structures. One of the advantages of these light sources is the possibility to obtain a small longitudinal beam size. To help reduce it, the longitudinal dispersion should be non-zero in some arcs of the accelerator. However small deviations in voltages of the accelerating structures can be enhanced by induced fields from circulating bunches due to the dependence of the flight time on the energy spread and the high quality factor of the superconducting radio-frequency cavities. Therefore, instabilities related with interactions of the electron bunches and longitudinal modes of the cavities can develop in the installation. Stability conditions for the interactions with fundamental accelerating mode of the split accelerating system are discussed. Numerical simulations are made for two projects - MARS and FSF.

WEPWO005

Microphonics Analysis of the SC 325 MHz CH-Cavity

cavity, simulation, vacuum, status

2319

M. Amberg, M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg, K. Aulenbacher
HIM, Mainz, Germany
K. Aulenbacher
IKP, Mainz, Germany

Since the walls of superconducting (sc) cavities are kept very thin to support the cooling process, even small mechanical disturbances can detune the cavity. One of the main sources of detuning a cavity is microphonics. These low-frequent vibrations caused by vacuum pumps or underground noise are transferred to the cryostat and excite mechanical resonances of the cavity which may lead to frequency shifts larger than the bandwidth. To determine the mechanical resonance frequencies of the sc 325 MHz CH-cavity (Crossbar-H-Mode) simulations with ANSYS Workbench have been performed in a first step. Additionally, microphonics measurements were taken at room temperature as well as in a vertical cryostat at 4K in the cryo-lab of the IAP, Frankfurt University. Furthermore, the contraction of the cavity walls and the resulting frequency shift due to the cavity cool-down has been measured. A comparison between simulation results and the measured values is presented in this paper.

WEPWO008

SRF Conical Half-wave Resonator Tuning Developments

cavity, simulation, target, cryomodule

2325

E.N. Zaplatin
FZJ, Jülich, Germany
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302.
A conical Half-Wave Resonator is considered as an option for a first accelerating cavity for β=v/c=0.11 with the resonance frequency 162.5 MHz for a high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory (Project X). We present results of different options of the cavity mechanical tuning. The "standard" tuning method of beam port deformations is an effective tuning method still requiring a relatively high tuning pressure. The side tuning is considered as a novel option for the resonance frequency adjustment featuring lower tuning force and an option of the structure design for the resonator frequency shift self compensation.

WEPWO056

Update of the Mechanical Design of the 650 MHZ β=0.9 Cavities for Project X

cavity, simulation, niobium, linac

2432

I.V. Gonin, M.H. Awida, M.H. Foley, C.J. Grimm, T.N. Khabiboulline, Y.M. Pischalnikov, V.P. Yakovlev
Fermilab, Batavia, USA

Five-cell elliptical 650 MHz β=0.9 cavities to accelerate 1 mA of average H⁻ beam current in the range 520-3000 MeV of the Project X Linac are currently planned. We will present the results of optimization of mechanical design of cavities with their Helium Vessel. We discuss the efforts to optimize the mechanical stability of the cavity versus the Helium bath pressure fluctuations, cavity tunability. We present also modal and thermal analysis; discuss tuner options and other issues.

WEPWO058

Recent Progress at Fermilab Controlling Lorentz Force Detuning and Microphonics in Superconducting Cavities

cavity, controls, cryomodule, SRF

2438

W. Schappert, Y.M. Pischalnikov
Fermilab, Batavia, USA

Funding: Work is supported by U.S. Department of Energy
SRF cavities are susceptible to detuning by mechanical deformations induced by the Lorentz force and microphonics. Providing the RF overhead required to maintain the accelerating gradient in detuned cavities can increase both the capital and operating costs of superconducting accelerators. Recent work at Fermilab has shown that active vibration control using a piezo actuator can reduce both Lorentz Force detuning and microphonics to the point where negligible RF overhead is required to maintain the accelerating gradient.

WEPWO086

Split Higher Order Modes in Superconducting Cavities

cavity, dipole, HOM, higher-order-mode

2495

H. Hahn, S.A. Belomestnykh, W. Xu
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE and award no. DE-SC0002496 to Stony Brook University with the US DOE.
Split resonances are a common appearance in superconducting cavities and were studied here on the specific example of the TE11 dipole resonance in five-cell copper models of the ERL and BNL3. The BNL3 cavity was designed to be suitable for the envisioned electron-hadron collider eRHIC. Achieving the required high-current performance depends on avoiding beam break-up instabilities by minimizing the Higher Order Modes (HOM) Q-values. This was attempted in the design phase and will be done with appropriate mode dampers in operation. The availability of a copper model provided a convenient opportunity to confirm the design and to study potentially nefarious high-Q resonances. The appearance of split resonances impeded the HOM identification and the theoretical interpretation as elipticity deformation is presented in this report.

WEPEA001

Simulation Studies of Longitudinal RF-noise and Phase Displacement Acceleration as Driving Mechanism for the MedAustron Synchrotron Slow Extraction

extraction, acceleration, simulation, synchrotron

2501

U. Dorda
EBG MedAustron, Wr. Neustadt, Austria
M. Benedikt, H.O. Schönauer, A. Wastl
CERN, Geneva, Switzerland

MedAustron is a synchrotron based hadron therapy and research facility located in Austria currently entering the installation stage. It is an implementation of the CERN-PIMMS design which proposed induction acceleration by a betatron core as the driving mechanism for the third-order slow resonant extraction. Primarily in order to increase the accelerators flexibility towards future irradiation schemes but also as back-up options, two alternative extraction driving mechanism have been studied: Longitudinal RF-noise and phase displacement acceleration. The advantages as well as the corresponding limitations are explained, analytical estimates and particle tracking results performed with the 2D tracking codes LONG1D and a specifically developed Python based simulation code are presented.

WEPEA018

Further Improvement of the PTC-ORBIT Code to Model Realistic Operation of High-beam Power Synchrotrons

injection, synchrotron, quadrupole, extraction

2534

A.Y. Molodozhentsev, E. Forest
KEK, Ibaraki, Japan

The combined PTC-ORBIT code has been developed a few years ago to study the dynamics of the high intensity proton beams in synchrotrons, including the nonlinear machine resonances and the space charge effects in the self-consistent manner. In order to extend the code abilities the time variation of the main elements of the synchrotron has been introduced into the PTC module of the code. This feature opens the direct way to model the multi-turn injection process and the slow extraction process by using realistic machine description, in particular the dynamic variation of the betatron tunes, strength of the bump magnets, dynamic resonance correction or resonance excitation. To demonstrate the code abilities the corresponding simulations for CERN PS Booster and for J-PARC Main Ring are discussed.

WEPEA021

Influence of the Vacuum Chamber Limitation on Dynamic Aperture Calculations

dynamic-aperture, vacuum, multipole, optics

2543

M. Attal
SESAME, Allan, Jordan

In a storage ring the evaluation of the dynamic aperture taking into account the vacuum chamber limitation is more accurate and may display nonlinearities that could not be seen in the conventional absolute dynamic aperture calculations. This has been investigated in this paper and demonstrated in SESAME dynamic aperture case where taking into account the vacuum chamber uncovered the seriousness of a 5th order resonance mainly when errors like high order multipoles were introduced to the lattice. The destructive effect of the 5th order resonance has been avoided by changing the fractional part of the tunes. The problem has also been more investigated using the Frequency Map Analysis technique.

WEPEA023

Space Charge Effects for Different CSNS/RCS Working Points

lattice, simulation, space-charge, emittance

2549

S.Y. Xu, N. Wang, S. Wang
IHEP, Beijing, People's Republic of China

The China Spallation Neutron Source (CSNS) operates at 25 Hz repetition rate with the design beam power of 100 KW. CSNS consists of an 80-MeV linac and a 1.6-GeV Rapid Cycling Synchrotron (RCS). Due to the high beam density and high repetition rate for CSNS/RCS, the rate of beam loss must be controlled to a very low level. The major source of beam loss is associated with resonances. Thus, choosing he best suitable working points on the tune diagram is important to reach low beam loss. Different tune areas are explored and compared by considering resonances and the effects of space charge, which can drive particles into the excited resonances. Different working points are simulated and compared by using the codes ORBIT and SIMPSONS.

WEPEA031

Slow extraction design in HIMM

extraction, synchrotron, septum, emittance

2567

J. Shi, W.P. Chai, J.W. Xia, J.C. Yang, Y.J. Yuan
IMP, Lanzhou, People's Republic of China

A heavy ion medical machine(HIMM) is proposed for cancer therapy in Lanzhou, China. The slow extraction design of the synchrotron is introduced in this paper. Eight sextupoles are used, four of them are for correcting the chromaticity and the rest for driving the 3rd-order resonance. In order to save the aperture of vacuum chamber, a 3-magnet bump is adopted during the extraction process. The phase space map in the entrance of the electrostatic septum and the last 3 turns' particle trajectory before particle extraction are given.

WEPEA034

Study on the Beam Dynamics in the RISP Driver Linac

linac, quadrupole, stripper, ion

2576

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

Abstract Rare Isotope Science Project (RISP) has been proposed as a multi-purpose accelerator facility for providing beams of exotic rare isotopes of various energies. The RISP driver linac which is used to accelerate the beam, for an example, Uranium ions from 0.3 MeV/u to 200 MeV/u consists of superconducting RF cavities and warm quadrupole magnets for focusing heavy ion beams. Requirement of the linac design is especially high for acceleration of multiple charge beams. In this paper, we present the requirements of dynamic errors and correction schemes to minimize the beam centroid oscillation and preserve beam losses under control.

WEPEA042

The PS Upgrade Programme: Recent Advances

injection, electron, emittance, extraction

2594

S.S. Gilardoni, S. Bart Pedersen, C. Bertone, N. Biancacci, A. Blas, D. Bodart, J. Borburgh, P. Chiggiato, H. Damerau, S. Damjanovic, J.D. Devine, T. Dobers, M. Gourber-Pace, S. Hancock, A. Huschauer, G. Iadarola, L.A. Lopez Hernandez, A. Masi, S. Mataguez, E. Métral, M.M. Paoluzzi, S. Persichelli, S. Pittet, S. Roesler, C. Rossi, G. Rumolo, B. Salvant, R. Steerenberg, G. Sterbini, L. Ventura, J. Vollaire, R. Wasef, C. Yin Vallgren
CERN, Geneva, Switzerland
M. Migliorati
University of Rome "La Sapienza", Rome, Italy

The LHC Injectors Upgrade project (LIU) has been initiated to improve the performances of the existing injector complex at CERN to match the future requirements of the HL-LHC. In this framework, the Proton Synchrotron (PS) will undergo fundamental changes for many of its main systems: the injection energy will be increased to reduce space-charge effects, the transverse damper will be improved to cope with transverse instabilities the RF systems will be upgraded to accelerate higher beam intensity and brightness. These hardware improvements are triggered by a series of studies meant to identify the most critical performance bottlenecks, like space charge, impedances, longitudinal and transverse instabilities, as well as electron-cloud. Additionally, alternative production schemes for the LHC-type beams have been proposed and implemented to circumvent some of the present limitations. A summary of the most recent advances of the studies, as well as the proposed hardware improvements is given.

WEPEA043

Working Point and Resonance Studies at the CERN PS

injection, controls, octupole, focusing

2597

A. Huschauer, M. Benedikt, H. Damerau, P. Freyermuth, S.S. Gilardoni, R. Steerenberg, B. Vandorpe
CERN, Geneva, Switzerland

The increase of luminosity demanded by the High Luminosity LHC (HL-LHC) requires an increase of beam intensity, which might result in instabilities appearing at injection energy in the CERN PS. Transverse head-tail instabilities have already been observed on operational LHC beams and a stabilizing mechanism as an alternative to linear coupling is currently being studied. It consists of reducing the mode number of the transverse oscillation by changing linear chromaticity and in succession completely suppressing the instability by a transverse damper system with appropriate bandwidth. Therefore, a chromaticity correction scheme at low energy exploiting the intrinsic possibilities offered by special circuits mounted on top of the main magnet poles, the Pole Face Windings (PFW), has been examined. The presence of destructive betatron resonances, which restrict the choice of the injection working point and the maximum acceptable tune spread, forms an additional limitation for high-brightness and high-intensity beams in the CERN PS. To improve the current working point control scheme, the influence of the P F W on the machine resonances is presented in this paper.

WEPEA052

Investigations on CERN PSB Beam Dynamics with Strong Direct Space Charge Effects Using the PTC-ORBIT Code

simulation, emittance, space-charge, injection

2621

V. Forte, E. Benedetto, C. Carli, M. Martini, B. Mikulec, E. Métral, F. Schmidt
CERN, Geneva, Switzerland
A.Y. Molodozhentsev
KEK, Ibaraki, Japan

The CERN PS Booster (PSB) is the first synchrotron of the LHC injector chain consisting out of four superposed rings and providing beam for many users. As part of the LIU project, the machine will be upgraded. Space charge and resonances are serious issues for the good quality of the beam at injection energy. Consequently simulations are needed to track the beam in the machine taking into account space charge effects: PTC-ORBIT has been used as tracking code. This paper presents simulations results compared with the measurements for machine performances evaluation and code-benchmarking purposes.

WEPEA054

CERN PS Optical Properties Measured with Turn-by-turn Orbit Data

simulation, optics, extraction, kicker

2627

C. Hernalsteens, T. Bach, S.S. Gilardoni, M. Giovannozzi, A. Lachaize, G. Sterbini, R. Tomás, R. Wasef
CERN, Geneva, Switzerland

The performance of the PS has been constantly increasing over the years both in terms of beam parameters (intensity and brightness) and beam manipulations (transverse and longitudinal splitting). This implies a very good knowledge of the linear and non-linear model of the ring. In this paper we report on a detailed campaign of beam measurements based on turn-by-turn orbit data aimed at measuring the optics in several conditions as well as the resonance driving terms. The goal of this study is to assess whether any specific correction system should be envisaged to achieve the required future performance.

WEPEA055

Quantitative Evaluation of Trapping and Overall Efficiency for Simple Models in One-degree of Freedom

simulation, controls, synchrotron, extraction

2630

C. Hernalsteens, C. Frye, M. Giovannozzi
CERN, Geneva, Switzerland
A. Bazzani
Bologna University, Bologna, Italy

A key ingredient for the Multi-Turn Extraction at the CERN Proton Synchrotron is the beam trapping in stable islands of transverse phase space. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, a method allowing an analytical estimation of the fraction of beam trapped into stable islands as a function of the Hamiltonian parameters is presented for a very simple model of the dynamics (pendulum) and is extended to the case of the interpolating Hamiltonian of the Hénon model, the latter being a good 2D model of the MTE dynamics. The analytical results are compared with numerical simulations. Additional numerical simulations are presented for the minimum trapping amplitude and a fitted model is proposed. Results are discussed in detail.

WEPEA070

Space Charge Effects and Limitations in the Cern Proton Synchrotron

emittance, space-charge, proton, injection

2669

R. Wasef, G. Arduini, H. Damerau, S.S. Gilardoni, S. Hancock, C. Hernalsteens, A. Huschauer, F. Schmidt
CERN, Geneva, Switzerland
G. Franchetti
GSI, Darmstadt, Germany

Space charge produces a large incoherent tune-spread which, in presence of betatronic resonances, could lead to beam losses and emittance growth. In the CERN Proton Synchrotron, at the current injection kinetic energy (1.4 GeV) and even at the future kinetic energy (2 GeV), space charge is one of the main limitations for high brightness beams and especially for the future High-Luminosity LHC beams. Several detailed studies and measurements have been carried out to improve the understanding of space charge limitations to determine the maximum acceptable tune spread and identify the most important resonances causing losses and emittance growth.

WEPEA072

Experimental Studies of Resonance Crossing in Linear Non-scaling FFAGs With the S-POD Plasma Trap

dipole, ion, focusing, betatron

2675

S.L. Sheehy, D.J. Kelliher, S. Machida, C.R. Prior
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
K. Fukushima, K. Ito, K. Moriya, H. Okamoto
HU/AdSM, Higashi-Hiroshima, Japan

In a linear non-scaling FFAG the betatron tunes vary over a wide range during acceleration. This naturally leads to resonance crossing including first order integer resonances. The S-POD (Simulator for Particle Orbit Dynamics) plasma trap apparatus at Hiroshima University represents a physically equivalent system to a charged particle beam travelling in a strong focusing accelerator lattice. The S-POD system can be used as an ‘experimental simulation’ to investigate the effects of resonance crossing and its dependence on dipole errors, tune crossing speed and other factors. Recent developments and experiments are discussed.

WEPEA081

Local 3Qy Betatron Resonance Correction in the 2012 RHIC 250 GeV Run

sextupole, dynamic-aperture, proton, betatron

2696

Y. Luo, W. Fischer, T. Roser, V. Schoefer, C.M. Zimmer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In this article we performed numerical simulations to correct the local vertical third order betatron resonance 3Q_y in the interaction regions in the Yellow ring for the 2012 RHIC 250~GeV polarized proton run. Considering the main sources of skew sextupoles are located in the interaction regions, we used local bump methods to minimize their contributions to the global 3Q_y resonance driving term. Two kinds of correction orbit bumps are tested and the dynamic apertures with these correction strengths are calculated and compared.

WEPFI026

Design and Commissioning of the RF System of CYCIAE 14 Cyclotron

cyclotron, cavity, controls, low-level-rf

2759

Z.G. Yin, B. Ji, Y. Lei, P.Z. Li, G.F. Song, C. Wang, T.J. Zhang, Z.L. Zhao
CIAE, Beijing, People's Republic of China

The RF system of CYCIAE-14 consists of a set of 20kW amplifier, two 1/4λ RF cavities connected in central region, the transmission line and a set of LLRF system. The LLRF system, based on DDS and DSP, has achieved the close-loop adjustment of accelerating voltage and the resonant frequency. The RF system design for CYCIAE-14 was started in 2010, and the fabrication of the major equipments was finished in 2011. The installation and commissioning was completed in early 2012, satisfying the design requirements. This article describes the design of the RF system, and summarizes the difficulties encountered in the process of manufacture, installation and commissioning. Some of the problems caused by the transmission line and the RF leakage are analyzed, followed by the measures taken to solve these problems.

WEPFI027

The Measurement of the Ferrite Rings for the Mass Production RF Cavity of CSNS RCS

cavity, impedance, LLRF, booster

2762

H. Shi, W.L. Huang, B. Jiang, X. Li, W. Long, W.Y. Song, H. Sun, J.Y. Tang, C.L. Xie, C.L. Zhang, W. Zhang
IHEP, Beijing, People's Republic of China

The Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) will install 8 ferrite-loaded coaxial resonant cavities. The construction and measurement of prototype cavity have been finished. Based on the existing experiences, the small inner diameter (ID) rings T500/250/25-4M2 (mm) have been adopted for the mass production RF cavity, and the test results have shown that such rings can bear more RF magnetic flux density and have lower power loss. The characteristics of 60 small ID rings have been measured with two-ring test system, and we figured out that the rings have good consistence and the shunt impedance of all rings is above 100 Ω.

WEPFI054

Enlargement of Tuning Range in a Ferrite-tuned Cavity through Superposed Orthogonal and Parallel Magnetic Bias

cavity, factory, radiation

2812

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

Conventional ferrite-tuned cavities operate either with bias fields that are orthogonal or parallel to the magnetic RF-field. For a cavity that tunes rapidly over an overall frequency range around 100-400 MHz with high Q, we use ferrite garnets exposed to an innovative new biasing method consisting of a superposition of perpendicular and parallel magnetic fields. This method leads to a significant enlargement of the high-Q cavity tuning range by defining an operation point close to the magnetic saturation and thus improving ferrite material behaviour. A further advantage of this technique is the fast tuning speed resulting from the fact that tuning is carried out either with pure parallel biasing, or together with a very small change of operating point from perpendicular bias. In this paper, several scaled test models of ferrite-filled resonators are shown; measurements on the set-ups are compared and discussed.

WEPFI059

C-band RF Pulse Compressor for SwissFEL

coupling, 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.

WEPFI062

Precise Cavity Tuning System of a Low Output-impedance Second-harmonic Cavity at ISIS

cavity, impedance, cathode, beam-loading

2836

Y. Irie, S. Fukumoto, K. Muto, H. Nakanishi
KEK, Ibaraki, Japan
D.B. Allen, D. Bayley, N.E. Farthing, I.S.K. Gardner, R.J. Mathieson, A. Seville, J.W.G. Thomason
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J.C. Dooling, D. Horan, R. Kustom, M.E. Middendorf
ANL, Argonne, USA

A very low output-impedance (~35ohms) second-harmonic cavity system is being developed for high intensity proton accelerators. The final amplifier is comprised of a grounded cathode scheme with a feedback loop from anode to grid. Due to the Miller effect, the grid voltage waveform is seriously distorted even if only a few percent of sub-harmonic or higher harmonic are mixed in the generator current. Such distortion is much enhanced by the beam loading. In order to eliminate the effect of this distortion upon the phase detector used to achieve precise cavity tuning, a swept bandpass filter was applied to the grid voltage at the phase detector input. Filter design details and the result of high power tests are reported.

WEPFI081

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

klystron, linac, simulation, coupling

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.

WEPME023

Study of the Vibration of the AC Dipole and Magnetic Measurement Girder for CSNS/RCS

dipole, acceleration, damping, synchrotron

2980

R.H. Liu, L. Kang, H. Qu, G.Y. Wang, H.J. Wang, J. S. Zhang
IHEP, Beijing, People's Republic of China

The dipole magnet of the China Spallation Neutron Source Rapid-cycling Synchrotron (RCS) will be operated at a 25Hz sinusoidal alternating current which causes severe vibration. The vibration will influence the long-term safety and reliable operation of the magnet. By taking the magnet and magnetic measurement girder as a specific model system, a method for analyzing and studying the dynamic characteristic of the system is put forward by combining theoretical calculation with experimental testing. And the ctive vibration of magnet is different with passive vibration which was causes by ground vibration, so a new isolator was designed to decrease the vibratory force and avoid the resonance phenomenon.

WEPME052

LLRF Characterisation of the Daresbury International Cryomodule

LLRF, cavity, cryomodule, SRF

3046

L. Ma
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
P.A. Corlett, A.J. Moss
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The 2-cavity Superconducting RF (SRF) Linac cryomodule of the Accelerators and Lasers in Combined Experiments (ALICE) located at Daresbury Laboratory will be replaced by a new International ERL Cryomodule in early 2013. The improved 7-cell, 1.3 GHz SRF cavities will be characterised and compared with the original 9-cell cavities. Tests will be performed by driving the cavities by a VCO-PLL loop so that Q measurements, microphonics sensitivity and Lorentz force detuning can be analysed. A digital LLRF system using the LLRF4 board developed by Larry Doolittle has been developed at Daresbury Laboratory and will be installed on the upgraded cryomodule. This system is capable of controlled cavity filling to reduce waveguide reflection voltage, feedback/feed forward control and adaptive beam loading compensation. The new cryomodule will be evaluated with both the analog LLRF system and the digital LLRF system to allow for performance comparison. Cavity operation with high QL will also be tested to discover the feedback control limit as a function of inherent microphonics. This paper sets out to discuss the qualification process, testing and results of the upgraded cryomodule installation.

THYB101

Suppressing Transverse Beam Halo with Nonlinear Magnetic Fields

lattice, space-charge, damping, octupole

3099

S.D. Webb, D.T. Abell, D.L. Bruhwiler, J.R. Cary
Tech-X, Boulder, Colorado, USA
V.V. Danilov
ORNL, Oak Ridge, Tennessee, USA
S. Nagaitsev, A. Valishev
Fermilab, Batavia, USA

Funding: This work was supported in part by the US Department of Energy's Office of Science, Office of High Energy Physics, under grant No. DE-SC0006247.
Traditional space charge driven resonances, such as beam halo, arise due to the underlying linear nature of accelerator lattices. In this talk, we present initial results on a new class of intrinsically nonlinear lattices, which introduce a large tune spread naturally. The resulting nonlinear decoherence suppresses the onset of beam halo.

Slides THYB101 [63.510 MB]

THPEA048

The FPGA-based Power Monitoring System for TPS Facility

monitoring, controls, factory, LabView

3252

C.S. Chen, Z.-D. Tsai
NSRRC, Hsinchu, Taiwan

There are more and more non-linear electronic equipments such as inverters using in facility nowadays. These non-linear electronic equipments let us achieve energy saving, but induce other electrical pollution to the whole power grid in contrast. How to monitor the electrical noises from these non-linear equipments becomes an important issue. In this article, a set of power quality monitoring system based on FPGA and PAC has been built because of the programmability and fast processing speed. By using this monitoring system, any abnormality in power system and its spectrum will be recorded thoroughly. On the other hand, the maintainer could follow the trace of noise and then propose a suitable solution to eliminate the electrical interference too.

THPFI051

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

dipole, coupling, electron, 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.

THPFI052

Application of Atmospheric Plasma-sprayed Ferrite Layers for Particle Accelerators

plasma, vacuum, gun, electron

3406

F. Caspers, M. Betz, S. Federmann, M. Taborelli
CERN, Geneva, Switzerland
K. K., C.A.M. Schulz
Surface Engineering Institute, RWTH Aachen University, Aachen, Germany
J.X. Wu
IMP, Lanzhou, People's Republic of China

A common problem in all kind of cavity like structures in particle accelerators is the occurrence of RF-resonances. Typically, ferrite plates attached to the walls of such structures like diagnostic devices, kickers or collimators, are used to dampen those undesired modes. However the heat transfer rate from these plates to the walls is rather limited. Brazing ferrite plates to the walls is not possible in most cases due to the different thermal expansion coefficients. To overcome those limitations, atmospheric plasma spraying techniques have been investigated. Ferrite layers with a thickness from 50 micron to about 300 micron can be deposited on metallic surfaces like stainless steel exhibiting good thermal contact and still reasonable absorption properties. In this paper the technological aspects of plasma deposition are discussed and results of specifically developed RF loss measurement procedures for such thin magnetically lossy layers on metal are presented. This kind of layers can also be applied for the production of high temperature RF power loads and related examples will be shown.

THPME008

Experimental Study of Magnetic Properties for Magnet Material in CYCIAE-100

focusing, cyclotron, factory, vacuum

3525

J.Q. Zhong, T. Cui, M. Li, C. Wang, Z.H. Wang, J.J. Yang, T.J. Zhang
CIAE, Beijing, People's Republic of China

The magnetic property of magnet material is one of the key factors that influence the distribution of magnetic field in large scale cyclotrons, especially embody on the vertical focusing of field and the first harmonic field error in cyclotron. According to the requirements of the physical design of CYCIAE-100, we have studied the pivotal factors, which impact on the maximum permeability, coercivity and B-H curve of material of CYCIAE-100 magnet, including the cooling rate during magnetic annealing and residual stress. The study results will be shown in this paper.

THPWA019

THEORY RESEARCH ON APPLICATION OF CT TECHNOLOGY TO SHIELDED NUCLEAR MATERIAL DISCRIMINATION

electron, neutron, radiation, factory

3669

Y. Zhang, H.B. Chen, Q. Gao, J. Shi
TUB, Beijing, People's Republic of China

Smuggling of nuclear material is a serious threat to security of international society. Formal research on nuclear material discrimination can fulfil customs inspection requirement. This paper designs a situation that nuclear material which is packaged and shielded by heavy metal need to be discriminated accurately on the condition that the object being detected cannot be dismantled. Calculation results prove nuclear material could be discriminated accurately while the ideal condition is fulfilled. If multi-energy X-ray source is used the discrimination accuracy is declined. However the accuracy could be improved while energy spectrum shaping technique is used.

THPWO030

Recent Progress in Beam Commissioning of J-PARC Linac

linac, DTL, simulation, radiation

3827

M. Ikegami, Z. Fang, K. Futatsukawa, T. Miyao
KEK, Ibaraki, Japan
Y. Liu
KEK/JAEA, Ibaraki-Ken, Japan
T. Maruta
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
A. Miura, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan

The beam operation of J-PARC linac has been restored from the earthquake, and started to pursue higher beam power operation. We have also started to prepare for coming energy and intensity upgrade. In this paper, we review recent progress in beam commissioning of J-PARC linac with emphasis on the beam loss mitigation and preparation for the upgrade.

THPWO033

High Intensity Beam Trial of up to 540 kW in J-PARC RCS

injection, simulation, proton, linac

3836

H. Hotchi, H. Harada, N. Hayashi, M. Kinsho, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Irie
KEK, Ibaraki, Japan
S. Kato
Tohoku University, Graduate School of Science, Sendai, Japan

Recently we have performed a high intensity beam trial of up to 540 kW. In this paper, beam intensity dependece and injection painting parameter dependence of beam loss, observed in this beam experiment, will be discussed with the corresponding numerical simulation results.

THPWO068

Resonance Frequency Control Characteristics of the 100-MeV Drift Tube Linac

controls, DTL, proton, linac

3912

H.-J. Kwon, Y.-S. Cho, J.-H. Jang, H.S. Kim, K.T. Seol, Y.-G. Song
KAERI, Daejon, Republic of Korea

Funding: This work was supported by the Ministry of Science and Technology of the Korean Government.
A 100-MeV, 20mA proton accelerator has been developed by KAERI (Korea Atomic Energy Institute). Total 11 DTL (Drift Tube Linac) tanks are used to accelerator the proton beam from 3-MeV to 100-MeV. A RCCS (Resonance frequency Control Cooling System) has been developed to control the resonance frequency of each DTL tank. The coolant for the drift tube and quadrupole magnets are supplied by the RCCS, whereas the wall coolant temperature maintains constant at 27 degree C by using the DI water supplied from the utility. In this paper, the resonance frequency control schemes are summarized and the control characteristics of the DTL tank by using the RCCS are discussed.

THPWO087

Measurement of Resonant Space Charge Effects in the J-PARC Linac

emittance, linac, simulation, space-charge

3966

D.C. Plostinar
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Liu, T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan

Traditionally, high intensity linac designs follow the “equipartitioning condition”, a strict control of the transverse and longitudinal tune ratios throughout the linac that ensures space-charge driven emittance exchange between the longitudinal and transverse planes is minimised. However, equipartitioning imposes strict rules on the linac design, thus limiting the design options and increasing the overall construction cost. More recently, practical tools have been developed that offer guidelines in designing non-equipartitioned linacs, by charting the stable regions in a tune ratio diagram (Hofmann’s Charts). While these stability diagrams have been backed by extensive multiparticle simulations and some experimental evidence, questions still remain regarding the practical consequences of crossing the resonances. In this paper preliminary results are presented from an experimental study conducted in the J-PARC linac, where for the first time we measured both the transverse and longitudinal emittance for different linac working points. A detailed analysis will be presented as well as a discussion on the wider implications of this experiment.