IPAC2017 - List of Keywords (coupling)

Paper	Title	Other Keywords	Page
MOPIK013	Design and Simulation of a C-Band Photocathode RF Gun With a Coaxial Coupler for UEM	gun, electron, cavity, impedance	525
	T. Chen, Y.J. Pei, Y. Song USTC/NSRL, Hefei, Anhui, People's Republic of China
	A ultrafast electron microscope (UEM) has been become much more important research instrument and has been widely used in many fields. As a part of the UEM, a photocathode RF gun working at C-band frequency of 5712MHz is being developed, which provides electron beam with high qualities for UEM. This paper presents the physics and structure design, including optimization of cavity shape parameter for improving shunt impedance and Q factor. We adopt a novel coaxial coupler, which could decrease the multipole field and decrease the focusing coil size, build better accelerating field in the RF gun. In this paper, we discussed the simulation process and results of the RF gun, especially the design of the coaxial input coupler was described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK013
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MOPIK076	Optimization of Dynamic Aperture with Constraints on Linear Chromaticity	luminosity, sextupole, simulation, lattice	705
	H. Sugimoto, H. Koiso, A. Morita, Y. Ohnishi, K. Oide, D. Zhou KEK, Ibaraki, Japan
	This paper presents numerical technique to optimize dynamic aperture with constraints on linear chromaticity of optical functions. By solving a set of linear equations at each iteration step of dynamic aperture optimization, the linear chromaticity is kept unchanged. The variable range of tuning knobs is taken into account in order to make the technique applicable to practical use. Numerical simulations assuming the SuperKEKB design lattice are performed, and it is demonstrated that the dynamic aperture obtained with the presented scheme is almost comparable to that without constraints. Luminosity simulations assuming weak-strong model show that the constraints lead to improvements of luminosity performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK076
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MOPIK088	Vertical Emittance Reduction in the SSRF Phase II Project	emittance, quadrupole, alignment, sextupole	733
	C.L. Li, B.C. Jiang, Z.B. Li, M.Z. Zhang, Q.L. Zhang, W.Z. Zhang SINAP, Shanghai, People's Republic of China
	The Shanghai Synchrotron Radiation Facility (SSRF) Phase II beamline project (SSRF Phase II) will implement the new lattice with dual-canted insertion devices, superbends and superconducting wiggler. The emittance coupling is one of the most important parameters for the high brightness storage ring light sources. It is often less than 1% in the third-generation storage ring light sources. In this paper, the sensitivity of emittance coupling to magnetic alignment errors in the SSRF Phase II is presented. Sixty skew quadrupole magnets are utilized to correct the emittance coupling with gradient descent algorithm. The emittance coupling obtained in the SSRF Phase II lattice is below 0.3%.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK088
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MOPIK097	Vertical Dispersion and Betatron Coupling Correction for FCC-ee	emittance, quadrupole, sextupole, collider	752
	S. Aumon, B.J. Holzer CERN, Geneva, Switzerland K. Oide KEK, Ibaraki, Japan
	The FCC-ee project foresees to build a 100 km e⁺/e⁻ circular collider for precision studies and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 10³⁵ cm^-2s^-1. To reach such performances, an extreme focusing of the beam is required in the interaction regions with a low vertical beta function of 2~mm at the IPs. Moreover, the FCC-ee physics program requires very low emittances never achieved in a collider with 1~nm for ε_x and 2~pm for ε_y, bringing down the coupling ratio to 2/1000. Thus, coupling and vertical dispersion sources have to be controlled carefully. This paper describes the tolerance of the machine to magnet alignment errors as well as the optics correction methods that were implemented, such as the Orbit Dispersion Free Steering, in order to bring the vertical dispersion to reasonable values. The correction of the betatron coupling, being also a very important source of emittance growth, has been integrated to a challenging correction scheme to keep the vertical emittance as low as possible.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK097
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MOPVA037	Development and Commissioning of the Doppler-Shift Unit for the Measurement of the Ion Species Fractions and Beam Energy of the ESS Proton Source	proton, linac, software, optics	936
	C.A. Thomas, T.J. Shea ESS, Lund, Sweden J. Fils GSI, Darmstadt, Germany Y. Lussignol, P. Mattei CEA/DSM/IRFU, France Ø. Midttun University of Bergen, Bergen, Norway L. Neri INFN/LNS, Catania, Italy F. Senée, O. Tuske CEA/IRFU, Gif-sur-Yvette, France
	ESS proton source is in going to be soon delivered to the ESS project. In order to qualify the source, a series of beam instrumentation diagnostics have been designed and produced. In particular, a specific spectrograph dedicated to the fraction species measurement is currently commissioned. This instrument not only is capable of measuring the fraction species produced by the source, but also it can measure their energy and energy spread, the mass of the different species, and additional spectral rays coming from the gas species in presence in the vacuum chamber. We present in this paper the commissioning of this instrument, the Doppler Shift unit, dedicated to the measurement of the fraction species.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA037
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MOPVA044	Conditioning of the Power Couplers for the ESS Elliptical Cavity Prototypes	vacuum, cavity, controls, pick-up	957
	C. Arcambal, P. Carbonnier, M. Desmons, G. Devanz, T. Hamelin, C. Marchand, C. Servouin CEA/DRF/IRFU, Gif-sur-Yvette, France C. Darve ESS, Lund, Sweden
	In the framework of the European Spallation Source (ESS), some power couplers have been designed and manufactured to supply, with RF power, the medium-beta (β=0.67) elliptical cavities of the cryomodule demonstrator. The power couplers work at 704.4 MHz and are tested up to 1.2 MW (repetition rate=14 Hz, RF pulse width close to 3.6 milliseconds). The CEA Saclay is in charge of the design, the manufacturing, the preparation and the conditioning of these power couplers. In this paper, after a general presentation of the power couplers used in the ESS LINAC and their characteristics, we give some détails about the manufacturing and then we describe the different steps of the preparation (cleaning), the assembly of the couplers on the coupling box in cleanroom, the baking of the couplers and the conditioning procedure. Finally, the experimental results obtained in travelling and standing waves on the first pairs of couplers will be shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA044
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MOPVA046	120kW RF Power Input Couplers for BERLinPro	booster, cavity, SRF, linac	960
	B.D.S. Hall, V. Dürr, F. Göbel, J. Knobloch, A. Neumann HZB, Berlin, Germany
	The 50-MeV, 100-mA energy-recovery-linac (ERL) demonstration facility BERLinPro is currently undergoing construction at HZB. The high power injection system, that will deliver a beam at 6.5MeV, is split into a 1.4 cell SRF Photo injector and three Cornell-style 2-cell boosters. The injector and two of the booster cavities will provide about 2MeV each and must handle up to 220 kW of beam loading. New, cERL-based 115-kW high power couplers needed for the cavities' twin coupler system have begun manufacture. The design, optimization and manufacturing considerations of these couplers are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA046
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MOPVA051	Design of the High Power 1.5 GHz Input Couplers for BESSY VSR	cavity, operation, simulation, HOM	978
	E. Sharples, M. Dirsat, J. Knobloch, A.V. Vélez HZB, Berlin, Germany
	The Variable pulse length Storage Ring (BESSY VSR) upgrade to BESSY II at Helmholtz-Zentrum Berlin (HZB) requires an upgrade on the RF systems in the form of high-voltage longitudinally focusing super conducting RF cavities of 1.5 GHz ad 1.75 GHz. For operation, coaxial RF power couplers capable of handling 13 kW peak power at standing wave operation are required for both the 1.5 GHz and 1.75 GHz cavities. The coupler is based on a design by Cornell University with modifications to suit frequency and coupling requirements. The coupler is intended to provide variable coupling with a range of Qext from 6x10⁶ to 6x10⁷ to allow flexibility to adjust to operating conditions of BESSY VSR. Here we present the RF design of the high-power coaxial coupler for BESSY VSR along with the design of the test stand for conditioning a pair of couplers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA051
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TUPAB012	Comparison of Prismatic and Circular Biperiodical Accelerating Structures of 27 GHz Operating Frequency	linac, simulation, impedance, alignment	1330
	Yu.D. Kliuchevskaia, S.M. Polozov MEPhI, Moscow, Russia
	As known a biperiodical accelerating structure (BAS) represents as a system based on disk loaded waveguide (DLW) operating on Pi/2 mode and is widely used for the compact electron linacs. Earlier such structure with operating frequency of 27 GHz was proposed for medical application and beam dynamics simulations and electrodynamics modeling were done [1-2]. It was shown that such structure manufacturing should have very high accuracy and can be manufactured using electro erosive technology only. It is very complex for axi-symmetrical geometry to use such technology. Interesting option will to use a prismatic geometry BAS. In this report the design of a prismatic and disk-loaded BAS will discus, simulation results and analysis will presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB012
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TUPAB043	Design and Simulation of Voltage Multiplier Column of a 300keV, 10mAParallel Fed Cockcroft Walton Electron Accelerator for Industrial Applications	simulation, electron, software, gun	1421
	M. Nazari, F. Abbasi Davani, F. Ghasemi Shahid Beheshti University, Tehran, Iran S. Ahmadiannamin ILSF, Tehran, Iran
	In this article a 300keV, 10mA multiplier column has been designed for a parallel fed Cockcroft Walton electron accelerator for industrial applications. The parallel fed Cockcroft Walton multiplier is a capacitive coupling multiplier with diode rectification which can convert an input RF voltage to a low ripple output DC voltage. In this research tried to get a low ripple (300keV output) dc voltage. At first, the voltage multiplier column has been simulated with pspice simulation software. After doing the pspice simulations, optimum value of different parameters has been get. At the end we try to get the optimum values of pspice simulations with a mechanical design with CST STODIO. The mechanical design of voltage multiplier and its equivalent circuit hah a good accordance with each other.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB043
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TUPAB045	Design and Construction of a Pre-Buncher for Iranian Low Energy Linear Accelerator	cavity, electron, linac, simulation	1428
	S. Ahmadiannamin ILSF, Tehran, Iran M. Bahrami, M.R. Khalvati, M. Lamehi, H. Shaker, M. Shirshekan IPM, Tehran, Iran
	Iranian IPM low energy linear accelerator project (e-Linac) is in its final steps for commissioning. Beam dynamic simulations with and without Pre-buncher prior to buncher was done. The results represent improvement in capturing efficiency better than 25% by application of Pre-buncher cavity. In this paper, we present the simulation, construction, RF measurements and vacuum test results. After construction, we measured RF reflection coefficient better than -33 dB in the nominal frequency of 2997.9 MHz with quality factor of 4500.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB045
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TUPAB136	Coupling and Polarization Control in a mm-wave Undulator	undulator, polarization, controls, electron	1647
	F. Toufexis, J. Neilson, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437. To reduce the linac energy required for an FEL radiating at a given wavelength, and hence its size, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling the electromagnetic fields while maintaining overmoded features for power handling capability and electron beam wakefield mitigation. We have designed a mm-wave undulator cavity at 91.392 GHz. This undulator requires approximately 1.4 MW for sub-microsecond pulses to generate an equivalent K value of 0.1. Transferring such amounts of power in mm-wave frequencies requires overmoded corrugated waveguides, and coupling through irises creates excessive pulsed heating. We have designed a novel mode launcher that allows coupling power from a highly overmoded corrugated waveguide to the undulator through the beam pipe. Additionally, this mode launcher can be used along with grating polarizers to control the polarization of the produced light. F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB136
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TUPIK021	Microwave Injection and Coupling Optimization in ECR and MDIS Ion Sources	plasma, ion, ion-source, ECRIS	1724
	G. Torrisi, A.C. Caruso, G. Castro, L. Celona, S. Gammino, O. Leonardi, A. Longhitano, D. Mascali, E. Naselli, L. Neri, G. Sorbello INFN/LNS, Catania, Italy E. Naselli Catania University, Catania, Italy G. Sorbello University of Catania, Catania, Italy
	The fundamental aspect of coupling between microwave and plasma of the Electron Cyclotron Resonance Ion Source (ECRIS) and Microwave Discharge Ion Source (MDIS) is hereinafter treated together with ad hoc microwave-based plasma diagnostics, as a key element for the next progress and variations with respect to the classical ECR heating mechanism. The future challenges for the production of higher-charge states, higher beam intensity, and high absolute ionization efficiency also demand for the exploration of new heating schemes and synergy between experiments and modeling. An overview concerning microwave transport and coupling issues in plasma-based ion sources for particle accelerator will be given in the paper, along with perspectives for the design of next generation sources.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK021
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TUPIK053	A Broadband Transverse Kicker Prototype for Intra-Bunch Feedback in the CERN SPS	kicker, impedance, simulation, feedback	1812
	M. Wendt, I.A. Alonso Romero, S.J. Calvo, W. Höfle, O.R. Jones, E. Montesinos CERN, Geneva, Switzerland
	A transverse intra-bunch feedback system is currently under study at CERN for the SPS, to mitigate beam instabilities caused by electron clouds and coupled transverse modes (TMCI). This feedback system is designed for a bandwidth of 1 GHz, and based on a digital feedback controller and broadband power amplifiers. For the kicker, a periodic, quasi-TEM slotted transmission-line structure is foreseen which promises to meet the bandwidth requirements. This paper discusses the electromagnetic design and the mechanical implementation of a prototype kicker, demonstrating its performance and limitations based on numerical simulations.
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TUPIK099	Beam-Based Alignment for the Rebaselining of CLIC RTML	emittance, sextupole, quadrupole, alignment	1939
	Y. Han, L. Ma SDU, Shandong, People's Republic of China A. Latina, D. Schulte CERN, Geneva, Switzerland
	The first stage of the CLIC is proposed to be at 380 GeV. So the Ring To Main Linac (RTML), which transport the beams from the damping ring to main linac with minimal emittance growth, should be restudied due to the new beam properties. In this paper the two bunch compressors in the RTML are redesigned. Then a complete study of the static beam-based alignment techniques along RTML is presented. The beam-based correction includes one-to-one and dispersion-free steering, then a global correction using tuning bumps is applied to reduce the final emittance and mitigate the effects of coupling. The results showed that the emittance growth budgets can be met both in the horizontal and vertical planes.
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TUPVA001	Progress on the Optics Corrections of FCC-hh	quadrupole, dipole, injection, lattice	2019
	D. Boutin, A. Chancé, B. Dalena CEA/IRFU, Gif-sur-Yvette, France B.J. Holzer, D. Schulte CERN, Geneva, Switzerland
	The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the three options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group, and the natural evolution of existing LHC. Studies are ongoing about the evaluation of the various magnets mechanical errors and field errors tolerances in the arc sections of FCC-hh, as well as an estimation of the correctors strengths necessary to perform the corrections of the errors. In this study advanced correction schemes for the residual orbit, the linear coupling and the ring tune are described. The impact of magnet tolerances on the residual errors, on the correctors technological choice and on the beam screen design are discussed. In particular the effect of the dipole a2 error is emphasized.
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TUPVA013	Lifetime of Asymmetric Colliding Beams in the LHC	simulation, luminosity, proton, ion	2067
	J.M. Jowett, R. Alemany-Fernández, M.A. Jebramcik, T. Mertens, M. Schaumann CERN, Geneva, Switzerland
	In the 2013 proton-nucleus (p-Pb) run of the LHC, the lifetime of the lead beam was significantly shorter than could be accounted for by luminosity burn-off. These effects were observed at a lower level in 2016 and studied in more detail. The beams were not only asymmetric but the differences in the bunch filling schemes between protons and Pb nuclei led to a wide variety of beam-beam interaction sequences in the bunch trains. The colliding bunches were also of different sizes. We present an analysis of the data and an interpretation in terms of theoretical models.
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TUPVA031	Impact of Incoherent Effects on the Landau Stability Diagram at the LHC	octupole, betatron, damping, simulation	2125
	C. Tambasco, J. Barranco García, X. Buffat, T. Pieloni CERN, Geneva, Switzerland J. Barranco García, X. Buffat, T. Pieloni EPFL, Lausanne, Switzerland
	Instability thresholds are explored at the Large Hadron Collider (LHC) by means of the computation of the Landau Stability Diagrams (SD). In the presence of diffusive mechanisms, caused by resonance excitations or noise, the SD can be reduced due to the modification of the particle distribution inside the beam. This effect can lead to a possible lack of Landau damping of the coherent modes previously damped by lying within the unperturbed SD area. The limitations deriving from coherent instabilities in the LHC is crucial in view of future projects that aim to increase the performance of the LHC such as the High-Luminosity upgrade (HL-LHC). Simulation tools for the computation of the SD have been extended in order to take into account the incoherent effects from long tracking through the detailed model of the accelerator machine. The model includes among others beam-beam interactions and octupoles and the interplay between both is addressed. Finally the simulation results are compared to the Beam Transfer Function (BTF) measurements in the LHC.
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TUPVA063	RF Tuning Tests on the Coupled FRANZ RFQ-IH-DTL	rfq, DTL, resonance, cavity	2224
	A. Almomani, U. Ratzinger IAP, Frankfurt am Main, Germany M. Heilmann GSI, Darmstadt, Germany
	The neutron beam at the FRANZ facility will be produced by the 7Li(p, n)7Be reaction using an intense 2 MeV proton beam. These protons will be accelerated from 120 keV to 2 MeV by a coupled 4-Rod-type RFQ and a 8 gap interdigital H-type structure (IH-DTL). This coupled RFQ-IH-cavity will be operated at 175 MHz in cw mode and it has a total length of about 2.3 m. The two structures (RFQ, IH-DTL) are internally coupled inductively, and consequently only one RF-amplifier providing a total power up to 250 kW is needed for operation. The IH-DTL is RF tuned together with an Al-RFQ model, before final IH-DTL installation in the FRANZ cave, while the original RFQ was already installed in the beam line. After RF power and beam tests the coupled structure will be installed and continued with RF and beam. This paper will be focused on the RF tuning process and the main results will be presented.
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TUPVA064	Updated Cavities Design for the FAIR p-Linac	linac, cavity, proton, quadrupole	2227
	A. Almomani, M. Busch, F.D. Dziuba, U. Ratzinger, R. Tiede IAP, Frankfurt am Main, Germany F.D. Dziuba, C.M. Kleffner GSI, Darmstadt, Germany
	The research program of antiproton beams for the FAIR facility requires a dedicated 68 MeV, 70 mA proton injector. This injector will consist of an RFQ followed by six room temperature Crossbar H-type CH-cavities operated at 325 MHz. The beam dynamics had been revised by IAP Frankfurt in collaboration with GSI-FAIR in Darmstadt to further optimize the design. This step was followed by cavity RF design. The detailed mechanical cavity design will begin in 2017, while the quadrupole lenses are under production already. In this paper, besides an overview the RF design of the coupled cavities with integrated focusing triplets will be a main focus.
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TUPVA069	Test of a High Power Room Temperature CH DTL Cavity	cavity, operation, impedance, DTL	2237
	N.F. Petry, S. Huneck, K. Kümpel, H. Podlech, U. Ratzinger, M. Schwarz IAP, Frankfurt am Main, Germany
	The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) is planned to deliver ultra-short neutron pulses at high intensities and repetition rates. As part of FRANZ a 175 MHz room temperature 5-gap CH DTL cavity was designed and built. Its main task will be focusing the particle bunch longitudinally at 2 MeV particle energy. Furthermore the CH cavity can also be used to increase the energy as well as decrease it by 0.2 MeV. The rebuncher and its cooling system is optimized to work with a 5 kW amplifier. The amplification system is intended to provide continuous power (cw mode). Due to its operating parameters being nearly identical to the requirements of the MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) Project, experience for future cavity designs was gained. This includes considerations concerning cooling with use of a 12 kW amplifier. The recent results of conditioning and high power tests will be presented.
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TUPVA136	Using Sloppy Models for Constrained Emittance Minimization at the Cornell Electron Storage Ring (CESR)	emittance, lattice, storage-ring, simulation	2418
	W.F. Bergan, A.C. Bartnik, I.V. Bazarov, H. He, D. L. Rubin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.P. Sethna Cornell University, Ithaca, New York, USA
	Funding: DOE DE-SC0013571 NSF DGE-1144153 In order to minimize the emittance at the Cornell Electron Storage Ring (CESR), we measure and correct the orbit, dispersion, and transverse coupling of the beam.* However, this method is limited by finite measurement resolution of the dispersion, and so a new procedure must be used to further reduce the emittance due to dispersion. In order to achieve this, we use a method based upon the theory of sloppy models.** We use a model of the accelerator to create the Hessian matrix which encodes the effects of various corrector magnets on the vertical emittance. A singular value decomposition of this matrix yields the magnet combinations which have the greatest effect on the emittance. We can then adjust these magnet ‘‘knobs'' sequentially in order to decrease the dispersion and the emittance. We present here comparisons of the effectiveness of this procedure in both experiment and simulation using a variety of CESR lattices. We also discuss techniques to minimize changes to parameters we have already corrected. * J. Shanks, D.L. Rubin, and D. Sagan, Phys. Rev. ST Accel. Beams 17, 044003 (2014). ** K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003).
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WEZB1	Review and Prospects of RF Solid State Amplifiers for Particle Accelerators	cavity, power-supply, booster, vacuum	2537
	P. Marchand SOLEIL, Gif-sur-Yvette, France
	Thanks to the growth of high power semiconductor technology, solid state power amplifier (SSPA) systems with several hundred kW RF power are now available for various accelerator fields. Following the successful development at 352 MHz that took place at SOLEIL in the 2000s, the technology was transferred to industry and SSPAs at different frequencies, power levels, and pulse lengths have been widely adopted. In this paper we report about the SOLEIL experience with SSPAs and review the used or planned SSPAs in other accelerator facilities.
	Slides WEZB1 [13.860 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEZB1
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WEPAB098	Dielectrically-Loaded Waveguide as a Microwave Undulator for High Brillance X-Rays at 45 - 90 Kev	undulator, brightness, photon, operation	2812
	R. Kustom, A. Nassiri, G.J. Waldschmidt ANL, Argonne, Illinois, USA
	The HEM12 mode in a cylindrical, dielectrically-loaded waveguide provides E and H fields on the central axis that are significantly higher than the fields on the conducting walls. This structure, operating near the cutoff frequency of the HEM12 mode, spans a frequency range where the wavelength and phase velocity vary significantly. This property can be exploited to generate undulator action with short periods for the generation of high brightness x-rays. The frequency range of interest would be from 18 to 34.5-GHz. The goal would be to generate x-rays on the fundamental mode over a range of 45 to 90-kev. The tunability would be achieved by changing the source frequency while maintaining a constant on-axis equivalent undulator field strength of 0.5-T.
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WEPIK006	Cancellation of the Leak Field from Lambertson Septum for the Beam Abort System in the SuperKEKB	quadrupole, sextupole, emittance, septum	2918
	N. Iida, M. Kikuchi, K. Kodama, T. Mimashi, T. Mori, Y. Ohnishi, K. Oide, H. Sugimoto, M. Tawada KEK, Ibaraki, Japan
	The first commissioning of SuperKEKB, Phase 1, was performed from February 2016 for five months. A Lambertson septum magnet is utilized to vertically extract the aborted beam, kicked by the horizontal abort kickers upstream into a beam dump. This magnet creates unexpected leak field with a non-negligible skew quadrupole component to the stored beam. Two kinds of skew quadrupole magnets are installed on both sides of the Lambertson septum. One is additional skew windings on the sextupole magnet, and the other is a skew quadrupole magnet with permanent magnets. This paper will report that the cancellations of the leak fields was successful and useful for optics correction.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK006
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WEPIK067	Beam-Dynamics Simulation Studies for the HESR	dynamic-aperture, simulation, dipole, multipole	3084
	J.H. Hetzel, U. Bechstedt, J. Böker, A. Lehrach, B. Lorentz, S. Quilitzsch, H. Soltner, R. Tölle FZJ, Jülich, Germany A. Lehrach RWTH, Aachen, Germany
	The High Energy Storage Ring (HESR) is part of the future Facility for Antiproton and Ion Research (FAIR) placed in Darmstadt (Germany). The HESR is designed for antiprotons with a momentum range from 1.5 GeV/c to 15 GeV/c, but will as well be suitable to provide heavy ion beams with a momentum range from approximately 0.6 GeV/c to 5.8 GeV/c. To guarantee smooth operation it is crucial to verify and to optimize the design with beam-dynamics simulations. Within recent studies* calculations based on a variant of the Lyapunov exponent were carried out to estimate the dynamic aperture. The studies could reproduce expected influences as reduced aperture due to tune resonances and tune shifts due to coupling. Thus they can be extended to investigate the dynamic behaviour of the beam and identify the main restrictions to the dynamic aperture near the chosen betatron tune. Furthermore ongoing measurements of the magnetic fields of the already produced bending dipoles and quadrupoles deliver a more precise insight to the harmonic content of these elements. Thus the existing simulations could now be updated by including the new measurement results. *J. Hetzel, A. Lehrach, U. Bechstedt, J. Böker, B. Lorentz, R. Tölle: Towards Beam-Dynamics Simulations Including More Realistic Field Descriptions for the HESR, IPAC'16
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK067
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WEPIK089	Characterization of Resonant Impedances of CERN-SPS Gate Valves	impedance, simulation, resonance, vacuum	3139
	T. Kaltenbacher, J. Repond, C. Vollinger CERN, Geneva, Switzerland
	For the CERN High Luminosity LHC project, a doubling of bunch intensity is foreseen. However, this intensity increase is currently limited by the LHC injector chain, in part due to longitudinal multi-bunch instabilities in the SPS. Therefore, the implementation of an accurate SPS impedance model was started some time ago in order to obtain a better understanding of instability sources and develop mitigation measures. In this paper, we present the electromagnetic characterization of commonly used all-metal gate valves with respect to their contribution to the SPS longitudinal impedance. The valve impedance was evaluated with commercially available EM-field simulation programs and verified with RF-bench measurements. Using this input, it was possible to obtain in particle simulations the dependence of the multi-bunch stability threshold on the number of these valves. A practical means of mitigation is to use a commercially available impedance shielded version of these gate valves. We also present the associated reduction in beam coupling impedance and the expected gain in beam stability if all existing unshielded valves are replaced by shielded valves.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK089
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WEPIK090	Characterization of Shielding for the CERN-SPS Vacuum Flanges With Respect to Beam Coupling Impedance	impedance, shielding, vacuum, resonance	3143
	T. Kaltenbacher, C. Vollinger CERN, Geneva, Switzerland
	Longitudinal multi-bunch instabilities in the CERN-SPS pose a serious limitation for future beam intensities required for high luminosity LHC. Hence, an impedance model for the SPS accelerator was developed from which one group of vacuum flanges could be identified as being a major culprit for these instabilities. These flanges support high impedance modes and their impact on beam stability was traced to a longitudinal mode at about 1.4GHz. For improvement of multi-bunch stability threshold, this group of flanges will be shielded as part of an impedance reduction campaign. We describe the evaluation of different impedance shielding designs proposed to reduce the longitudinal beam coupling impedance of this group of vacuum flanges in the SPS. EM-field simulations were performed to identify remaining resonances in these vacuum flanges with impedance shield prototypes installed, and the simulation models were benchmarked with RF-measurements. Depending on the performance and other parameters, the most suitable shield design will be selected, built and installed. As a first step, the installation of one shielding design in some positions in the SPS is planned for the beginning of 2017.
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WEPIK091	Amplitude Dependent Closest Tune Approach Generated by Normal and Skew Octupoles	octupole, simulation, resonance, injection	3147
	E.H. Maclean, T. Persson, R. Tomás CERN, Geneva, Switzerland
	Amplitude dependent closest tune approach, an action dependent analogue of the DQmin generated by linear coupling, was observed in the LHC during Run1. It restricts the accessible resonance free area of the tune diagram and by altering tune spread has the potential to impact upon Landau damping. A theoretical description of such behaviour, generated by normal octupoles and linear coupling has recently been validated in the LHC, however simulation has established that amp-dependent closest approach may also be generated by a combination of normal and skew octupoles. This paper summarizes these simulation based observations.
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WEPIK092	Effect of Linear Coupling on Nonlinear Observables at the LHC	dynamic-aperture, injection, simulation, octupole	3151
	E.H. Maclean, F.S. Carlier, M. Giovannozzi, T. Persson, R. Tomás CERN, Geneva, Switzerland
	Simulation work during LHC Run 1 established that linear coupling had a large impact on nonlinear observables such amplitude detuning and dynamic aperture. It is generally taken to be the largest single source of uncertainty in the modelling of the LHC's nonlinear single particle dynamics. Measurements in 2016 sought to confirm this impact of linear coupling with beam. This paper summarizes the observed influence of linear coupling on various nonlinear observables in the LHC.
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WEPIK095	Evaluation of Longitudinal Beam Impedance in the Beam Gas Ionization Monitor of the CERN-PS Accelerator	impedance, simulation, wakefield, detector	3163
	N. Nasr Esfahani, T. Kaltenbacher, J.W. Storey, C. Vollinger CERN, Geneva, Switzerland
	The recently observed beam induced heating issues in the BGI monitors of the LHC which could have been occurred due to a strong coupling between the beam and the localized modes at the sensor location showed the general importance of a thorough evaluation of the beam coupling impedance and the corresponding heat deposit in beam monitoring equipments. This paper is devoted to the examination of the beam coupling impedance and beam induced heating for a currently under development beam gas ionization (BGI) monitor which is intended to be a part of the CERN Proton Synchrotron (PS) beam monitoring equipment. Details of the EM and wake field simulations for this BGI monitor together with the RF measurement results and power loss calculations will be presented.
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WEPIK096	Assessment of Beam Impedance for the CERN-PS Booster Wire Scanner	simulation, impedance, booster, proton	3167
	T. Kaltenbacher, N. Nasr Esfahani, C. Vollinger CERN, Geneva, Switzerland
	It is well known that performance of accelerators critically depends on the interaction of high intensity beams with the surrounding structures. As a result of these beam interactions, it is required at CERN to characterize the beam coupling impedance of each new machine element that is to be installed in the accelerator ring. In the framework of the LIU (LHC Injectors Upgrade) project, a new design of rotational wire scanner to be used in the PS Booster is currently under development. As an intermediate step, the prototype of this wire scanner was evaluated with respect to its longitudinal beam coupling impedance. Depending on the performance of this machine element, it is planned to replace existing wire scanners in other machines at CERN (e.g. PS-Booster, PS and SPS) with very similar designs. This paper presents the simulations and describes the measurement methods used for benchmarking electromagnetic simulations performed for the impedance evaluation of the LIU wire scanner for the PS-Booster. Additionally, the device was fitted with an RF feed-through in order to monitor and attenuate certain undesired modes supported by this structure.
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WEPIK102	Measurement of RF Resonances and Measured Impact on Transverse Multibunch Instabilities from In-vacuum Insertions Devices	vacuum, resonance, damping, dipole	3188
	G. Rehm DLS, Oxfordshire, United Kingdom
	Diamond Light Source has currently 15 in-vacuum insertion devices (ID) installed, mostly built in-house. Their measured impact on multi-bunch mode damping as a result of varying magnet gap was shown before, now we augment these with measurements of broadband frequency spectra with stored beam obtained using an antenna placed in the ID vacuum. Finally, we present off-line measurements of resonances in the ID vessel acquired using a vector network analyser and two antennae installed in-vacuum.
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WEPIK109	Experimental Study of Vertical-Longitudinal Coupling Induced by Wakefields at CesrTA	wakefield, lattice, simulation, electron	3200
	S. Wang, J.D. Perrin, S. Poprocki, D. L. Rubin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by NSF PHY-1416318, PHYS-1068662 Transverse vertical wakefields can cause vertical beam size growth in accelerators. Here we report recent measurements and simulations of wakefields from movable scrapers at the CesrTA. The charge dependent vertical beam size growth was observed while a single scraper was inserted through the top of the chamber. No change in the beam size was observed with top and bottom scrapers inserted symmetrically. The apparent growth in the vertical beam size was due in large part to the y-z coupling (vertical crabbing) induced by the monopole wake of the asymmetric scraper configuration. We explored this y-z coupling by varying vertical betatron phase advance between the vertical beam size monitor and the scrapers. In addition, we found that existing residual, current independent y-z coupling could be compensated by the scraper wake. Predictions of a tracking simulation are in good agreement with the measurements.
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WEPIK111	Derivation of a Finite Element Formulation From a Lagrangian for the Electromagnetic Potentials	electromagnetic-fields, operation, resonance, interface	3208
	A.R. Vrielink, M.H. Nasr, S.G. Tantawi SLAC, Menlo Park, California, USA
	Conventional electromagnetic finite element solvers typically solve a weak formulation of the Helmholtz wave equation. While mathematically this approach is correct, it does not fully reflect the fundamental physics involved. We offer an alternative variational formulation which is not derived from the Helmholtz wave equation but is more fundamentally tied to the physics of the system: a Lagrangian for the electromagnetic potentials. Solving for the potentials directly allows for a natural accounting of the beam wave interaction. It could also potentially avoid the issue of deleterious spurious modes inherent when selecting the Coulomb gauge and enforcing the subsequent divergence free condition, eliminating the need for vector basis functions. Herein we present the theory and the resulting formulation including a discussion on gauge fixing. We conclude with some numerical results demonstrating the potential of this formulation.
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WEPVA055	Pre Orbit Correction Based on Tunnel Level Measurement in SuperKEKB	alignment, optics, factory, emittance	3385
	A. Morita, H. Koiso, Y. Ohnishi, H. Sugimoto KEK, Ibaraki, Japan
	The SuperKEKB accelerator tunnel has about 30mm displacement in the vertical direction. From the result of optics correction simulation with the tunnel displacement, it was decided that the beamline components align against the smoothed line of the measured tunnel level in order to save the alignment cost and time. In order to compensate the large tunnel displacement, the pre orbit correction based on the tunnel level measurement is applied at the beginning of the phase-1 commissioning, and the beam circulation is achieved with the small number of magnet adjustments. We report the result of the pre orbit correction.
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WEPVA094	Study of an Improved Beam Screen Design for the LHC Injection Kicker Magnet for HL-LHC	impedance, kicker, injection, simulation	3471
	V. Vlachodimitropoulos, M.J. Barnes, L. Ducimetière, L. Vega Cid, W.J.M. Weterings CERN, Geneva, Switzerland
	During Run 1 of the LHC, one of the injection kicker magnets (MKIs) occasionally exhibited an excessively high ferrite temperature, caused by coupling of the high intensity beam to the real impedance of the magnet. Beam-screen upgrades have been very effective in reducing beam coupling impedance during Run 2. However, temperature measurements during LHC operation have shown that one end of the MKIs ferrite yoke is consistently hotter than the other: this effect is due to highly non-uniform beam induced power deposition along the kicker. Electromagnetic and thermal simulations show that part of the ferrite yoke will be above its Curie temperature when the LHC is operated with HL-LHC beam parameters, which could increase the turn-around time between fills of the LHC. An impedance mitigation study is presented in this paper with emphasis on the effect of the beam screen layout upon both total beam induced power deposition and its longitudinal distribution. Results of complex thermal simulations, to benchmark the effectiveness of the proposed schemes, are reported. To validate the proposed modification a test bench measurement was performed and preliminary results are discussed
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WEPVA095	Preliminary Estimate of Beam Induced Power Deposition in a FCC-hh Injection Kicker Magnet	kicker, impedance, injection, collider	3475
	A. Chmielinska, M.J. Barnes, W. Bartmann, F. Burkart, B. Goddard CERN, Geneva, Switzerland A. Chmielinska EPFL, Lausanne, Switzerland
	The Future Circular Collider for hadrons (FCC-hh) will require a fast injection kicker system that is highly reliable and that does not limit accelerator performance. Important considerations in the design of such a system are machine protection constraints, collider filling factor and hence rise and fall times of the kicker magnet field. Fast rise time kicker magnets are generally ferrite loaded transmission line type magnets with a rectangular shaped aperture. The beam coupling impedance of the kicker magnets is crucial, as this can be a dominant contribution to beam instabilities. In addition, beam-induced heating of the ferrite yoke due to the real component of the longitudinal beam coupling impedance needs to be controlled: if the ferrite temperature exceeds the Curie point this impacts the ability to inject beam and hence the availability of the machine. This paper presents estimates for the beam induced power deposition in the ferrite yoke, based on a calculated FCC beam spectrum and an analytical model of longitudinal impedance for unshielded kicker magnets.
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WEPVA101	Review of Stripline Beam Impedance: Application to the Extraction Kicker for the CLIC Damping Rings	impedance, simulation, kicker, extraction	3499
	C. Belver-Aguilar, M.J. Barnes CERN, Geneva, Switzerland
	The beam coupling impedance of the stripline kicker for beam extraction from the CLIC Damping Rings (DRs) has been studied analytically, numerically with CST Particle Studio (PS) and measured in the laboratory, although not all the results were understood. In order to have a better knowledge about the beam coupling impedance of a stripline kicker, a simple model has been first studied, with flat electrodes and a cylindrical beam pipe. From this preliminary study, a new approach for the dipolar component of the horizontal impedance has been derived, when considering both odd and even operating modes of the striplines. This new approach has been used to understand the differences found between the predicted transverse impedance and the two wire measurements carried out in the laboratory for the prototype CLIC DR striplines. Future tests of beam coupling impedance with beam in the ALBA Synchrotron Ligth Source will complete this study.
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WEPVA128	The Data Acquisition System and Inspection Equipment on Vibration Evaluation for Deionized and Cooling Water Pumps in TPS	status, operation, data-acquisition, alignment	3568
	Y.-H. Liu, Y.-C. Chung, C.K. Kuan, Z.-D. Tsai NSRRC, Hsinchu, Taiwan
	The purpose of this paper is to evaluate the vibration amplitude and spectrum for TPS water pump systems. The utility systems operate continuously since 2014, some of deionized and cooling water pumps produced higher vibration amplitude and noise during operation. The possibly reason could be poor system accuracy, inappropriate installation and commission adjustment. The data acquisition system on vibration evaluation for deionizes water pumps was established in 2016. Accord-ing to the long-tern vibration amplitude recording, the system operational status could be clarified. After vibra-tion test for several months, the bearing of booster deion-ized water pump was found abrasive since coupling be-tween motor and pump misaligned. Besides, the founda-tion of copper deionized water pump system was broken and observed by rapidly increase vibration amplitude in short term. The water pump systems were repaired and maintained base on vibration evaluation. There is still some remain problems for deionized and cooling water pump systems. The utility systems could prevent mal-function through regular vibration inspection and daily data acquisition.
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THPAB020	Coupling Impedances and Collective Effects for FCC-ee	impedance, vacuum, collective-effects, collider	3734
	E. Belli, M. Migliorati University of Rome La Sapienza, Rome, Italy G. Castorina, B. Spataro, M. Zobov INFN/LNF, Frascati (Roma), Italy A. Novokhatski SLAC, Menlo Park, California, USA S. Persichelli LBNL, Berkeley, California, USA
	A very important issue for the Future Circular Collider (FCC) is represented by collective effects due to the self-induced electromagnetic fields, which, acting back on the beam, could produce dangerous instabilities. In this paper we will focus our work on the FCC electron-positron machine: in particular we will study some important sources of wake fields, their coupling impedances and the impact on the beam dynamics. We will also discuss longitudinal and transverse instability thresholds, both for single bunch and multibunch, and indicate some ways to mitigate such instabilities.
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THPAB032	Estimates of Collective Effects in the HALS Storage Ring Having the First Version Lattice	emittance, impedance, storage-ring, lattice	3770
	N. Hu, Z.H. Bai, W. Li, Q. Luo, L. Wang USTC/NSRL, Hefei, Anhui, People's Republic of China
	The Hefei Advanced Light Source (HALS) is a diffraction-limited storage ring with a beam energy of 2.0 GeV. Recently the first version lattice has been designed for the HALS storage ring, and the natural emittance is about 18 pm·rad. In this paper, we study the collective effects in this storage ring, including calculations of intra-beam scattering effect and Touschek lifetime, and estimates of the thresholds of some single-bunch and multi-bunch instabilities.
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THPAB040	Destabilising Effect of Linear Coupling in the LHC	simulation, damping, octupole, operation	3791
	L.R. Carver, D. Amorim, N. Biancacci, X. Buffat, K.S.B. Li, E. Métral, B. Salvant, M. Schenk CERN, Geneva, Switzerland
	During operation in 2015 and 2016, some transverse instabilities were observed when either the coupling (or closest tune approach) C- was large, or when the tunes were moved closer together. This motivated a campaign of simulations on the effect of linear coupling on the transverse stability. Measurements made during operation and with dedicated beam time have been found to confirm the predictions. This paper will detail the results of the linear coupling studies and relate them to operation of the LHC in the future.
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THPAB046	SixTrack for Cleaning Studies: 2017 Updates	collimation, ion, scattering, collider	3811
	A. Mereghetti, R. Bruce, F. Cerutti, R. De Maria, A. Ferrari, M. Fiascaris, P.D. Hermes, D. Mirarchi, P.G. Ortega, D. Pastor Sinuela, E. Quaranta, S. Redaelli, K.N. Sjobak, V. Vlachoudis CERN, Geneva, Switzerland J. Molson LAL, Orsay, France Y. Zou IHEP, Beijing, People's Republic of China
	SixTrack is a single particle tracking code for simulating beam dynamics in ultra-relativistic accelerators. It is widely used at the European Organisation for Nuclear Research (CERN) for predicting dynamic aperture and cleaning inefficiency in large circular machines like the Super Proton Synchrotron (SPS), the Large Hadron Collider (LHC) and the Future Circular Collider (FCC). The code is under continuous development, to both extend its physics models, and enhance performance. The present work gives an overview of developments, specifically aimed at extending the code capabilities for cleaning studies. They mainly involve: the online aperture check; the possibility to perform simulations coupled to advanced Monte Carlo codes like Fluka or using the scattering event generator of the Merlin code; the generalisation of tracking maps to ion species; the implementation of composite materials of relevance for the future upgrades of the LHC collimators; the physics of interactions with bent crystals. Plans to merge these functionalities into a single version of the SixTrack code will be outlined.
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THPAB047	New Features of the 2017 SixTrack Release	simulation, electron, collimation, HOM	3815
	K.N. Sjobak, J. Barranco García, R. De Maria, E. McIntosh, A. Mereghetti CERN, Geneva, Switzerland M. Fitterer Fermilab, Batavia, Illinois, USA V. Gupta IIT, Guwahati, Assam, India J. Molson LAL, Orsay, France
	The SixTrack particle tracking code is routinely used to simulate particle trajectories in high energy circular machines like the LHC and FCC, and is deployed for massive simulation campaigns on CERN clusters and on the BOINC platform within the LHC@Home volunteering computing project. The 2017 release brings many upgrades that improve flexibility, performance, and accuracy. This paper describes the new modules for wire- and electron lenses (WIRE and ELEN), the expert interface for beam-beam element (BEAM/EXPERT), the extension of the number of simultaneously tracked particles, the new Frequency Map Analysis (FMA) postprocessing option, the generation of a single zip of selected output files (ZIPF) in order to extend the coverage of the studies in LHC@HOME (e.g. FMA and on-line aperture checks), coupling to external codes (DYNK-PIPE and BDEX), a new CMAKE based build- and test mechanism, and internal restructuring.
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THPAB056	Dynamic Aperture Studies of the Long-Range Beam-Beam Interaction at the LHC	simulation, emittance, luminosity, dynamic-aperture	3840
	M.P. Crouch, R.B. Appleby UMAN, Manchester, United Kingdom J. Barranco García, T. Pieloni, C. Tambasco EPFL, Lausanne, Switzerland X. Buffat, M. Giovannozzi, E.H. Maclean CERN, Geneva, Switzerland B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Long-range beam-beam interactions dictate the choice of operational parameters for the LHC, such as the crossing angle and β^* and therefore the luminosity reach for the collider. These effects can lead to particle losses, closed orbit effects and emittance growth. Defining how these effects depend on the beam-beam separation will determine the minimum crossing angle and the β^* the LHC can operate. In this article, analysis from a dedicated machine study is presented in which the crossing angle was reduced in steps and the impact on beam intensity and luminosity lifetimes were observed. Based on the observations during the machine study, the intensity decays are compared to expectations from models. Estimates of the luminosity reach in the LHC are also computed.
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THPAB079	Terahertz Chirper for the Bunch Compression of Ultra-Low Emittance Beams	emittance, electron, dipole, laser	3899
	A.R. Vrielink, A. Marinelli, E.A. Nanni SLAC, Menlo Park, California, USA
	Recent efforts have demonstrated the possibility of achieving ultralow transverse emittance beams for high brightness light sources and free electron lasers. While these lower emittances should translate to improved lasing efficiency and higher peak brightness in FELs, these beams are commensurately more vulnerable to coherent synchrotron radiation (CSR) for the selfsame reasons. Conserving these ultralow emittances through the bunch compressors in an FEL given their increased propensity to emit CSR is particularly challenging. We investigate the possibility of imposing a large energy chirp at terahertz wavelengths to reduce the required magnetic fields in the compressor, counteracting the ultralow emittance in the generation of CSR. A second, higher frequency THz chirper would then be used to dechirp the beam after the chicane. Operation at THz as opposed to conventional radiofrequencies offers significantly larger chirp at similar input powers, yet still with wavelengths greater than typical FEL bunch lengths (several femtoseconds). Potential experimental schemes will be suggested in the context of LCLS and their feasibility evaluated. S. Bettoni, M. Pedrozzi and S. Reiche, Phys. Rev. ST Accel. Beams. 18, 123403 (December, 2015).
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THPAB095	Detuning Compensation in SC Cavities Using Kalman Filters	cavity, controls, FPGA, operation	3938
	A. Ushakov, P. Echevarria, A. Neumann HZB, Berlin, Germany
	For CW driven superconducting cavities operating at small bandwidth, like in ERL or FEL light sources, it is mandatory to precisely control any source of detuning. Therefore, a Kalman [1] filter based approach was developed and implemented as FPGA firmware to act as the core part of a detuning compensation algorithm. It relies on a fit by a second order model to a measured transfer function of cavity's forced oscillations with damping, caused by piezo drives and data about observed current phase with some adjustable confidence rate. The initial data for this core is taken from field detection firmware on mTCA.4's SIS8300-L2 digitizer, transferred by low latency links to a carrier board equipped by piezo drive controller where the DSP processing by the Kalman algorithm performed. The processing is characterized by a 550 kHz rate in pipeline mode and occupies almost all DSP resources of the Spartan 6 FPGA chip. The experimental results of detuning compensating technique applied to a SC photoinjector cavity are presented in this contribution. Kalman, R. E. (1960): A New Approach to Linear Filtering and Prediction Problems, Transaction of the ASME, Journal of Basic Engineering, Pages 35-45.
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THPAB110	Custom Optomechanics for the Optical Synchronization System at the European XFEL	laser, timing, alignment, FEL	3976
	F. Zummack, M. Felber, C. Gerth, T. Lamb, J.M. Müller, M. Schäfer, H. Schlarb, C. Sydlo DESY, Hamburg, Germany
	Free-electron-lasers like the upcoming European XFEL demand highly reliable optical synchronization in range of few femtoseconds. The well known optical synchronization system at FLASH had to be re-engineered to meet XFEL requirements comprising demands like ten times larger lengths and raised numbers of optically synchronized instruments. These requirements directly convert to optomechanical precision and have yielded in a specialized design accounting for economical manufacturing technologies. These efforts resulted in reduced spatial dimensions, improved optical repeatability, maintainability and even reduced production costs. To account for thermal influences the heart of the optical synchronization system is based on an optical table made out of SuperInvar. To fully exploit its excellent thermal expansion coefficient, mechanical details need to be taken into account. This work presents the design and its realization of the re-engineered optomechanical parts of the optical synchronization system, comprising mounting techniques, link stabilization units and optical delay lines for high drift suppression.
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THPAB111	Sub-Femtosecond Jitter Ultra High Performance Oscillators for Accelerator Timing	controls, cavity, electron, impedance	3979
	A. Gronefeld Ingenieurbüro Gronefeld, Herten, Germany
	Extremely stable RF-Sources are at the heart of Electron Beam Accelerators and impact beam quality and beam energy. Jitter requirements on those sources are very tight and linked to the quest of ever decreasing (XFEL) laser pulse length, currently in the tens of femtoseconds. For the Pohang Accelerator Laboratory in Pohang/Korea, a 2.856GHz phase-lockable oscillator with a jitter performance of 0.8fS (10kHz..10MHz) was developed and deployed, together with a master oscillator that supplies rubidium-stabilized 476MHz for synchronization. In terms of phase noise, these 2.856GHz oscillators exhibit -125dBc/Hz@1kHz, -145dBc/Hz@10kHz and -165dBc/Hz@100kHz offset, while reaching a noise floor of -180dBc/Hz. Using the same technology of a dielectric resonator oscillator, a 3.9GHz source was developed for the European XFEL at DESY/Hamburg, achieving 0.3fS (10kHz/10MHz). Phase noise is down to -125dBc/Hz@1kHz, -155dBc/Hz@10kHz and -175dBc/Hz@100kHz offset, with a noise floor of -180dBc/Hz. The strategy of designing ultra low phase-noise sources with dielectric resonators is outlined, and challenges and limitations within the oscillator design, but also measurement technology are presented.
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THPAB127	Development of 1.3 GHz Cavity Combiner for 24 kW CW SSA	cavity, simulation, linac, electromagnetic-fields	4020
	W. Liu, B. Du, G. Huang, L. Lin, L. Shang, W.B. Song USTC/NSRL, Hefei, Anhui, People's Republic of China
	The 24KW CW SSA (Solid-State Amplifier) is being developed to drive the 1.3GHz SC Linac used in a THz light source. The SSA adopts the compact all-in-one combining method ' cavity combiner, which is proposed and developed in recent years. This paper reports the R&D of the cavity combiner. The cavity combiner resonates in TM010 mode, coupling with 24 coaxial-connected 1kW amplifier modules. The cavity's electromagnetic characteristic is calculated by CST, and the mechanical structure including the input and output coupler has been designed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB127
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THPAB151	Online Optimisation Applications at SPS	injection, storage-ring, sextupole, quadrupole	4086
	T. Pulampong, P. Klysubun, S. Kongtawong, S. Krainara, P. Sudmuang SLRI, Nakhon Ratchasima, Thailand
	Optimisation of a particle accelerator with very limited diagnostic system is proved to be very challenging and complicated. Theoretical calculation and perfect machine model never guarantee the best solution in the actual machine. In this work, optimisation of injection system from Low energy Beam Transport line (LBT) to Siam Photon Source (SPS) storage ring and reduction of beam coupling employing Robust Conjugate Direction Search (RCDS) algorithm are demonstrated. New record improvement on injection efficiency and better coupling control will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB151
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THPIK015	Prototype Results of the ESR Barrier-Bucket System	cavity, impedance, accumulation, injection	4133
	M. Frey, P. Hülsmann, H. Klingbeil GSI, Darmstadt, Germany D. Domont-Yankulova, K. Groß, J. Harzheim, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany
	The experimental storage ring (ESR), operated at the GSI facility in Darmstadt, Germany, allows experiments with a variety of ion species. In combination with the existing electron cooler, its RF cavities have been used to demonstrate longitudinal beam accumulation in order to increase the beam intensity. Limitations of the existing narrow-band cavities led to the development of a magnetic alloy (MA) based broad-band cavity for the generation of Barrier-Bucket signals. The application of a pre-distortion method demands high linearity of the driver amplifier and highlights the importance of its selection process. In this contribution, the cavity and amplifier system design is described and data measured at a prototype system are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK015
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THPIK017	Field Uniformity Preservation Strategies for the ESS DTL: Approach and Simulations	DTL, simulation, linac, drift-tube-linac	4139
	G.S. Mauro, F. Grespan, A. Palmieri, A. Pisent INFN/LNL, Legnaro (PD), Italy P. Mereu, M. Mezzano, C. Mingioni, M. Nenni INFN-Torino, Torino, Italy
	The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4 % (3 ms pulse length, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. This paper presents the approach taken in order to preserve field flatness of DTL Tanks. This strategy required a set of simulations and consequent choices about RF design of DTL cells, RF coupler tuning and compensation, cooling of the DTL cells. Outcomes of these simulations and the experimental verifications of this approach are then explained.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK017
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THPIK035	Rf Properties of a 175 MHz High-Q Load Circuit	rfq, operation, linac, vacuum	4169
	S. Maebara, M. Sugimoto QST, Aomori, Japan
	For an RF input coupler test, a 175MHz high-Q load circuit based on a 6 1/8 in. co-axial waveguide was developed. This circuit consists of the RF input coupler, a trombone-type phase shifter and a stub tuner. The coupler with a loop antenna and the stub tuner are located in edges of the circuit, the loop antenna and the tuner work for a short plate. When RF input power is injected into the circuit, a high-voltage standing wave is excited by adjusting the tuner. The power of standing wave required for the tests is also accumulated due to its low resistive loss. At the operation frequency of 175 MHz, the resistive loss of 0.046ohm is measured and an equivalent RF power of 200 kW is accumulated by the RF input power of 740 W. In this circuit, the bandwidth is narrow to be ±5 kHz in S11 parameter of less -20 dB, but the equivalent RF power of 200 kW-14 sec CW could be achieved after sufficient RF aging. Using this high-Q load circuit, all the fabricated 9 couplers were successfully tested for RF contact defects, unnecessary low-Q value and extraordinary outgassing. This article describes these RF properties in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK035
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THPIK043	Design and Optimization of a 2MeV X-Band Side Coupled Accelerating Structure	impedance, simulation, linac, beam-loading	4193
	H. Yuan IHEP, Beijing, People's Republic of China
	An X-band bi-period side-coupled accelerating structure has been designed in this paper. The structure's working frequency is 9.3GHz. '/2 mode is chosen for the structure's stability. There are 11 accelerating cells, the first 5 work as non-light velocity part while the other 6 work as light velocity part. After CST simulation, the coupling constant between accelerating cells and coupling cells is 5%, efficient shunt impedance is 142M'/m. For the beam dynamic analysis, the particle energy is selected to be 2 MeV and the peak current is 60 mA for the radiation dosage limits by national standard. After Pamela optimization, the particle's capture efficiency is more than 30%. To feed power into the structure, a coupler is designed in the middle of the structure and the coupling coefficient is 1.4. The structure is manufactured and the measurement result accords well with designing value.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK043
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THPIK046	Design, Fabrication and Cold Test of a C-Band Barrel Open Cavity Pulse Compressor	cavity, klystron, simulation, vacuum	4200
	S. Shu Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China M. Hou, S. Pei, N.B. Song, J.R. Zhang, F. Zhao IHEP, Beijing, People's Republic of China
	The first prototype of the C band barrel open cavity (BOC) pulse compressor has been manufactured by the Institute of High Energy Physics (IHEP), Beijing, which is used to test the brazing process and the RF properties of the structure at low power. The whispering gallery mode TM6, 1,1 with an unload Q of 100, 000 was adopt to oscillate in the cavity, and the coupling factor was optimized to achieve the highest power gain. This paper mainly deals with the RF design, mechanical design and cold test of the C band BOC pulse compressor.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK046
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THPIK050	Measurement and Tuning of the RF Field for the CSNS DTL	DTL, cavity, operation, experiment	4210
	A.H. Li, M.X. Fan, B. Li, J. Peng, P.H. Qu, Y. Wang, X.L. Wu CSNS, Guangdong Province, People's Republic of China Q. Chen, S. Fu, K.Y. Gong, H.C. Liu IHEP, Beijing, People's Republic of China
	The CSNS DTL accelerates negative hydrogen ions from 3MeV to 80MeV with resonant frequency of 324MHz and peak current of 15mA. The CSNS includes four DTL cavities with diameter of 56.6cm and each length of 9 meters. RF properties research and measurement have been done to make sure the design and manufacture validate for beam operation. A new automatic system has been developed for measuring field distribution. The secondary derivation method is used to calculate the amount of the tuners to tune axial field flatness. The tilt of TS curve is used to judge the gap between the post couplers and drift tubes to achieve stability. At last the tanks have good flatness and strong stabilization, the field deviation is 2% with the standard deviation of 0.96%, and the maximum TS parameter is 65%/MHz. After the low power RF tuning experiment, the four tans have been installed in the tunnel, and have gotten good results of high power test and beam acceleration experiment.
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THPIK054	The X-Band Pulse Compressor for Tsinghua Thomson Scattering X-Ray Source	cavity, simulation, klystron, scattering	4214
	Y.L. Jiang, H.B. Chen, C. Cheng, W. Gai, J. Shi, P. Wang, X.W. Wu, H. Zha TUB, Beijing, People's Republic of China
	An X-band (11.424 GHz) high-power RF station is being built for Tsinghua Thomson scattering X-ray Source (TTX). The station aims to feed several X-band accelerating structures working at a high gradient of 80 MV/m. An X-band pulse compressor is designed to compress the RF pulse from 1.5 us to 100 ns and to generate more than 250 MW peak power from a 50MW klystron. This pulse compressor implements a resonate cavity housing the HE11-mode as the energy storage cavity, with a high quality factor Q of more than 10⁵. The detailed design of the high-Q cavity as well as the dedicate couplers of this pulse compressor are present in this work.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK054
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THPIK055	Power-Conditioning Cavity Design and Measurement of the Coaxial Coupler for the Injector of XiPAF Project	cavity, rfq, vacuum, DTL	4218
	Y. Lei, X. Guan, W. Wang, X.W. Wang, Q.Z. Xing, H.Y. Zhang, S.X. Zheng TUB, Beijing, People's Republic of China
	For the RF high power conditioning on coaxial power couplers of the XiPAF (Xi'an Proton Application Facility), the RF high power-conditioning cavity was designed and manufactured. The cavity consists of a rectangular reso-nant cavity with two ports, which one is connected with input coupler from RF power source and the other one is connected with output coupler, and a tuner. The tuning frequency range could cover 325 (+0.5, -9.5) MHz. The measured Q factors are matched with the design results generally. But the S-parameter is not ideal compared to the simulation. This paper will present the design and low power measurement results of the cavity
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK055
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THPIK058	Development of a S-Band Pulse Compressor	cavity, klystron, linac, laser	4227
	P. Wang, H.B. Chen, C. Cheng, J. Shi, X.W. Wu, H. Zha TUB, Beijing, People's Republic of China
	We designed and fabricated a pulse compressor for S-band high power test stand at Tsinghua University. This pulse compressor is made up of a sphere resonant cavity with quality factor of 100000 and a rf polarizer. It has the ability of compressing a pulse from 3.6 us to 300 ns with the power gain of 7. A short description of the pulse compressor is presented, together with the RF design and low level RF measurement.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK058
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THPIK067	A C-Band Compact Spherical RF Pulse Compressor for the SXFEL Linac Energy Upgrade	cavity, electron, simulation, linac	4248
	Z.B. Li, W. Fang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	A new compact C-band (5712 MHz) spherical RF pulse compressor has been designed for Shanghai Soft X-ray Free Electron Laser (SXFEL) facility energy upgrading at Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences (CAS). This pulse compressor contains one high Q0 spherical RF resonant cavity which works on two TE113 modes and a novel coupler. As there is only one storage cavity, this pulse compressor can be much smaller than the traditional SLED. With the coupling coefficient 4.9, the average power gain can be as high as 3.8. In this paper, the scheme of the C-band spherical pulse compressor and RF design are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK067
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THPIK117	High Efficiency High Power Resonant Cavity Amplifier for Accelerator Applications	cavity, operation, impedance, network	4374
	M.P.J. Gaudreau, D.B. Cope, E.G. Johnson, M.K. Kempkes, J. Kinross-Wright, R.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Funding: Work supported by US Department of Energy under contract DE-SC0015780 Diversified Technologies, Inc. (DTI) has designed and built a unique integrated resonant-cavity combined solid-state amplifier. The design radically simplifies solid-state transmitters to create favorable and straightforward scaling to high power levels. A crucial innovation is demonstration of an inherently reliable soft-failure mode of operation; a failure in one or several of these myriad combined transistors has negligible performance impact. In addition, this design couples the transistor drains directly to the cavity without first transforming to 50 Ohms, avoiding the otherwise-necessary multitude of circulators, cables, and connectors. A conventional amplifier has a complete set of electrical and cooling connections for every stage, resulting in many hundreds of connections for a high power transmitter'in some DTI designs, there are as few as four. This construction both reduces the cost and increases the power level at which it is cost-effective to employ a solid-state transmitter. The prototype has demonstrated multiple-transistor combining from 300 MHz to 1300 MHz, at powers up to 5 kW. This prototype is scalable to several hundred kW at these frequencies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK117
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THPIK118	Final Assembly and Testing of MICE RF Modules at LBNL	vacuum, cavity, low-level-rf, HOM	4377
	T.H. Luo, A.R. Lambert, D. Li, S.P. Virostek, J.G. Wallig LBNL, Berkeley, California, USA T.G. Anderson, A.D. Bross, D.W. Peterson Fermilab, Batavia, Illinois, USA M.A. Palmer BNL, Upton, Long Island, New York, USA Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA
	Funding: Work supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231 The international Muon Ionization Cooling Experiment aims to demonstrate the transverse cooling of a muon beam by ionization interaction with absorbers and re-acceleration in RF cavities. The final MICE cooling channel configuration has two RF modules, each housing a 201 MHz RF cavity to compensate the longitudinal energy loss in the absorbers. Two RF modules have been assembled and tested at LBNL. This paper reports the final assembly work, as well as the vacuum test and low level RF measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK118
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THPVA021	Dynamics of Spectator Particles in Space-Charge Fields of Mismatched Beams With Cross-Plane Coupling	space-charge, lattice, simulation, proton	4462
	M. Holz, V.G. Ziemann Uppsala University, Uppsala, Sweden
	In accelerators with high beam power, even moderate beam losses must be avoided. These losses are due to particles reaching large transverse amplitudes that form a low density halo orbiting the beam core. To study the beam halo formation, we place a spectator particle outside the beam core and let it interact with the core's electric field. The core, we model by a self-consistent transverse Gaussian beam including non-linear space charge forces and cross-plane coupling.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA021
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THPVA029	Study of Single Bunch Instabilities with Transverse Feedback at Diamond	feedback, operation, storage-ring, controls	4489
	E. Koukovini-Platia, R. Bartolini, A.F.D. Morgan, G. Rehm DLS, Oxfordshire, United Kingdom R. Bartolini JAI, Oxford, United Kingdom
	Single bunch instability studies have been carried out at Diamond with and without the transverse multi-bunch feedback (TMBF) system. Single bunch instability thresholds were measured for zero, positive and negative chromaticity values by increasing the current till the instability onset. The bunch-by-bunch feedback system was then used to suppress the motion of the bunch centroid and the new thresholds were measured in all chromaticity regimes. The feedback loop phase of the TMBF was changed from resistive to reactive as well as intermediate to find the optimal feedback settings that maximize the single bunch instability thresholds.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA029
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THPVA034	Comparison of the Coupling of Dipole Motion From Bunch to Bunch in an Electron Beam Caused by Electron Clouds at CesrTA Due to Variations in Bunch Length and Chromaticity	electron, damping, positron, dipole	4509
	M.G. Billing, L.Y. Bartnik, J.A. Crittenden, M.J. Forster, N.T. Rider, J.P. Shanks, M.B. Spiegel, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA R. Holtzapple CalPoly, San Luis Obispo, California, USA E.C. Runburg University of Notre Dame, Indiana, USA
	Earlier experiments at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) have probed the interaction of the electron cloud (EC) with a 2.1 GeV stored positron beam. Since a very low EC density is expected with the electron bunches, these results characterize the dependence of beam-vacuum chamber impedance interactions, which are common to both positron and electron beams. The experiments were performed on a 30-bunch electron train with a 14 ns spacing, at a fixed current of 0.75mA/bunch, at two different vertical chromaticity settings and for four different bunch lengths (or synchrotron tunes.) The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 20 turn-by-turn beam position monitors in CESR to measure the correlated bunch-by-bunch dipole motion and 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 analysis of the observations from these experiments and compare them with effects of the EC on the positron beam's dipole motion and coupling of the motion from each bunch to its succeeding bunches.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA034
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THPVA088	DESIGN AND CONSTRUCTION OF BRAZED SIDE COUPLED CAVITY OF MEDICAL ACCELERATOR	simulation, cavity, vacuum, electron	4664
	S. Ahmadiannamin, Kh.S. Sarhadi ILSF, Tehran, Iran F. Abbasi, M. Mohseni Kejani Shahid Beheshti University, Tehran, Iran M. Bahrami, M. Lamehi IPM, Tehran, Iran F. Ghasemi NSTRI, Tehran, Iran S. Zarei Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
	Two types of standing wave RF cavities are used routinely in construction of medical linear accelerators. These two types are Side coupled and on-axis coupled standing wave cavities. This selection is based on higher shunt impedance and compactness in comparison to travelling wave RF cavities. In this paper, we present the simulation, construction and measurement results of brazed section of 3 GHz side coupled RF cavity. It is the first successful experience of its kind in Iran. The obtained experiences can be used effectively for construction of side coupled thermionic RF guns and RF cavities of medical or industrial linacs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA088
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THPVA105	A Novel Side Coupling Standing-Wave Accelerating Structure for a Medical Linac	cavity, electron, impedance, linac	4710
	Zh. X. Tang, Z.H. Bai, Y.J. Pei USTC/NSRL, Hefei, Anhui, People's Republic of China
	A novel side coupling standing-wave (SW) accelerat-ing tube for low energy medical linac has been designed that operating frequency is 2998 MHz, operating mode is ', final energy is 6 MeV and beam current is 130 mA. A novel bridge hole between an accelerating cavity and coupling cavity has been utilized to reduce the mutual effect between two cavities and improve the anti-jamming capability and the long term stability. The inner end plate of the inlet of the first accelerating cavity in-cludes the nose cone to realize self-focusing in transverse to improve the beam quality. The simulation of the elec-tromagnetic field of structure and beam dynamic has been carried out with the SUPERFISH, CST Microwave studio and Parmela, respectively.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA105
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THPVA109	Design and Fuild-Solid-Heat Coupling Analysis of an Electrostatic Deflector for Hust SCC250 Proton Therapy Facility	septum, proton, cyclotron, extraction	4713
	S. Hu, K. Fan, L.X.F. Li, Z.Y. Mei, Z.J. Zeng, L.G. Zhang HUST, Wuhan, People's Republic of China
	The study of proton therapy equipment has earned more and more attention in recent years in China. A superconducting cyclotron based proton therapy facility is being developed for/at Huazhong University of Science and Technology (HUST). The proton beam is extracted by means of electrostatic deflectors followed by a series of magnetic channels. This paper introduces the design of an electrostatic deflector, including the structure optimization and the material selections. In order to minimize the risk of destruction caused by the proton beam loss, fluid-solid-heat coupling analysis for the deflector has been conducted by applying computational fluid dynamics (CFD) on ANSYS 16.0 software. The maximum temperatures of the septum in various cases of cooling water speed, septum thickness and material have been investigated respectively. The result based on thermal analysis will give us a valuable reference to choose a suitable configuration for the deflector.
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THPVA125	Status of Commissioning of Gantry 3 at the PSI PROSCAN Facility	operation, interface, controls, proton	4744
	A. Koschik, J.P. Duppich, M. Eichin, P. Fernandez Carmona, A. Gerbershagen, A.L. Lomax, D. Meer, S. Safai, J.M. Schippers, D.C. Weber PSI, Villigen PSI, Switzerland
	Paul Scherrer Institute currently extends its PROSCAN facility with a third gantry treatment room - Gantry 3, which is realized in a research collaboration with Varian Medical Systems. The main research goals at the PROSCAN facility include further development of precise spot scanning and optimized beam delivery with low dead-time for treatment of moving targets. Consequently Gantry 3 is designed to feature advanced pencil beam scanning technology with a large scan field size of 30x40cm, integrated cone beam CT functionality and will in the future allow fast energy layer switching. The main challenge in realizing Gantry 3 is the integration of the Varian Gantry into the existing PROSCAN control system environment, allowing seamless beam operation. Installation of the additional treatment room has started in summer 2015 followed by the integration and technical commissioning phases of the Gantry in 2016, all during full operation of the existing treatment areas at our facility. We report about the special challenges and achieved performance results during commissioning of the Varian Gantry system in combination with the PSI PROSCAN facility.
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THPVA146	Robust Linac Platform for Wide Replacement of Radioactive Sources	vacuum, linac, impedance, simulation	4805
	A.V. Smirnov, M.A. Harrison, A.Y. Murokh, A.Yu. Smirnov RadiaBeam Systems, Santa Monica, California, USA R.B. Agustsson, S. Boucher, T.J. Campese, J.J. Hartzell, K.J. Hoyt RadiaBeam, Santa Monica, California, USA E.A. Savin MEPhI, Moscow, Russia
	Funding: This work was supported by the U.S. Department of Energy (awards No. DE-SC-FOA-0011370). To improve public security and prevent the diversion of radioactive material for Radiation Dispersion Devices, development of an inexpensive, portable, easy-to-manufacture linac system is very important. Tubular structure with parallel pairs of rods crossed at 90 degrees suggests as high as 36% inter-cell coupling due to inherent compensation along with still substantial shunt impedance. Simultaneously it offers simplified brazing process and may dramatically simplify tuning of the entire structure. A novel design of a multi-cell, single-section, X-band structure for replacement of Ir192 source is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA146
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FRYBA1	From Niels Bohr to Quantum Computing	operation, controls, electron, factory	4852
	K. Mølmer AU, Aarhus, Denmark
	The development and use of accelerators for research has been closely linked to an era of modern physics which of course includes quantum mechanics. Niels Bohr was one of the foreground figures in the development of quantum mechanics and the IPAC community would like to recognise his contributions to this field in 2017, when IPAC takes place in Copenhagen, where he was active. Quantum computing is a subject of enormous potential and interest, and we would like to hear about the historical links to Niels Bohr and the so called Copenhagen School of Quantum Mechanics, and what we realistically can expect from this development.
	Slides FRYBA1 [2.490 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-FRYBA1
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Paper

Title

Other Keywords

Page

MOPIK013

Design and Simulation of a C-Band Photocathode RF Gun With a Coaxial Coupler for UEM

gun, electron, cavity, impedance

525

T. Chen, Y.J. Pei, Y. Song
USTC/NSRL, Hefei, Anhui, People's Republic of China

A ultrafast electron microscope (UEM) has been become much more important research instrument and has been widely used in many fields. As a part of the UEM, a photocathode RF gun working at C-band frequency of 5712MHz is being developed, which provides electron beam with high qualities for UEM. This paper presents the physics and structure design, including optimization of cavity shape parameter for improving shunt impedance and Q factor. We adopt a novel coaxial coupler, which could decrease the multipole field and decrease the focusing coil size, build better accelerating field in the RF gun. In this paper, we discussed the simulation process and results of the RF gun, especially the design of the coaxial input coupler was described.

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MOPIK076

Optimization of Dynamic Aperture with Constraints on Linear Chromaticity

luminosity, sextupole, simulation, lattice

705

H. Sugimoto, H. Koiso, A. Morita, Y. Ohnishi, K. Oide, D. Zhou
KEK, Ibaraki, Japan

This paper presents numerical technique to optimize dynamic aperture with constraints on linear chromaticity of optical functions. By solving a set of linear equations at each iteration step of dynamic aperture optimization, the linear chromaticity is kept unchanged. The variable range of tuning knobs is taken into account in order to make the technique applicable to practical use. Numerical simulations assuming the SuperKEKB design lattice are performed, and it is demonstrated that the dynamic aperture obtained with the presented scheme is almost comparable to that without constraints. Luminosity simulations assuming weak-strong model show that the constraints lead to improvements of luminosity performance.

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MOPIK088

Vertical Emittance Reduction in the SSRF Phase II Project

emittance, quadrupole, alignment, sextupole

733

C.L. Li, B.C. Jiang, Z.B. Li, M.Z. Zhang, Q.L. Zhang, W.Z. Zhang
SINAP, Shanghai, People's Republic of China

The Shanghai Synchrotron Radiation Facility (SSRF) Phase II beamline project (SSRF Phase II) will implement the new lattice with dual-canted insertion devices, superbends and superconducting wiggler. The emittance coupling is one of the most important parameters for the high brightness storage ring light sources. It is often less than 1% in the third-generation storage ring light sources. In this paper, the sensitivity of emittance coupling to magnetic alignment errors in the SSRF Phase II is presented. Sixty skew quadrupole magnets are utilized to correct the emittance coupling with gradient descent algorithm. The emittance coupling obtained in the SSRF Phase II lattice is below 0.3%.

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MOPIK097

Vertical Dispersion and Betatron Coupling Correction for FCC-ee

emittance, quadrupole, sextupole, collider

752

S. Aumon, B.J. Holzer
CERN, Geneva, Switzerland
K. Oide
KEK, Ibaraki, Japan

The FCC-ee project foresees to build a 100 km e⁺/e⁻ circular collider for precision studies and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 10³⁵ cm^-2s^-1. To reach such performances, an extreme focusing of the beam is required in the interaction regions with a low vertical beta function of 2~mm at the IPs. Moreover, the FCC-ee physics program requires very low emittances never achieved in a collider with 1~nm for ε_x and 2~pm for ε_y, bringing down the coupling ratio to 2/1000. Thus, coupling and vertical dispersion sources have to be controlled carefully. This paper describes the tolerance of the machine to magnet alignment errors as well as the optics correction methods that were implemented, such as the Orbit Dispersion Free Steering, in order to bring the vertical dispersion to reasonable values. The correction of the betatron coupling, being also a very important source of emittance growth, has been integrated to a challenging correction scheme to keep the vertical emittance as low as possible.

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MOPVA037

Development and Commissioning of the Doppler-Shift Unit for the Measurement of the Ion Species Fractions and Beam Energy of the ESS Proton Source

proton, linac, software, optics

936

C.A. Thomas, T.J. Shea
ESS, Lund, Sweden
J. Fils
GSI, Darmstadt, Germany
Y. Lussignol, P. Mattei
CEA/DSM/IRFU, France
Ø. Midttun
University of Bergen, Bergen, Norway
L. Neri
INFN/LNS, Catania, Italy
F. Senée, O. Tuske
CEA/IRFU, Gif-sur-Yvette, France

ESS proton source is in going to be soon delivered to the ESS project. In order to qualify the source, a series of beam instrumentation diagnostics have been designed and produced. In particular, a specific spectrograph dedicated to the fraction species measurement is currently commissioned. This instrument not only is capable of measuring the fraction species produced by the source, but also it can measure their energy and energy spread, the mass of the different species, and additional spectral rays coming from the gas species in presence in the vacuum chamber. We present in this paper the commissioning of this instrument, the Doppler Shift unit, dedicated to the measurement of the fraction species.

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MOPVA044

Conditioning of the Power Couplers for the ESS Elliptical Cavity Prototypes

vacuum, cavity, controls, pick-up

957

C. Arcambal, P. Carbonnier, M. Desmons, G. Devanz, T. Hamelin, C. Marchand, C. Servouin
CEA/DRF/IRFU, Gif-sur-Yvette, France
C. Darve
ESS, Lund, Sweden

In the framework of the European Spallation Source (ESS), some power couplers have been designed and manufactured to supply, with RF power, the medium-beta (β=0.67) elliptical cavities of the cryomodule demonstrator. The power couplers work at 704.4 MHz and are tested up to 1.2 MW (repetition rate=14 Hz, RF pulse width close to 3.6 milliseconds). The CEA Saclay is in charge of the design, the manufacturing, the preparation and the conditioning of these power couplers. In this paper, after a general presentation of the power couplers used in the ESS LINAC and their characteristics, we give some détails about the manufacturing and then we describe the different steps of the preparation (cleaning), the assembly of the couplers on the coupling box in cleanroom, the baking of the couplers and the conditioning procedure. Finally, the experimental results obtained in travelling and standing waves on the first pairs of couplers will be shown.

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MOPVA046

120kW RF Power Input Couplers for BERLinPro

booster, cavity, SRF, linac

960

B.D.S. Hall, V. Dürr, F. Göbel, J. Knobloch, A. Neumann
HZB, Berlin, Germany

The 50-MeV, 100-mA energy-recovery-linac (ERL) demonstration facility BERLinPro is currently undergoing construction at HZB. The high power injection system, that will deliver a beam at 6.5MeV, is split into a 1.4 cell SRF Photo injector and three Cornell-style 2-cell boosters. The injector and two of the booster cavities will provide about 2MeV each and must handle up to 220 kW of beam loading. New, cERL-based 115-kW high power couplers needed for the cavities' twin coupler system have begun manufacture. The design, optimization and manufacturing considerations of these couplers are presented.

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MOPVA051

Design of the High Power 1.5 GHz Input Couplers for BESSY VSR

cavity, operation, simulation, HOM

978

E. Sharples, M. Dirsat, J. Knobloch, A.V. Vélez
HZB, Berlin, Germany

The Variable pulse length Storage Ring (BESSY VSR) upgrade to BESSY II at Helmholtz-Zentrum Berlin (HZB) requires an upgrade on the RF systems in the form of high-voltage longitudinally focusing super conducting RF cavities of 1.5 GHz ad 1.75 GHz. For operation, coaxial RF power couplers capable of handling 13 kW peak power at standing wave operation are required for both the 1.5 GHz and 1.75 GHz cavities. The coupler is based on a design by Cornell University with modifications to suit frequency and coupling requirements. The coupler is intended to provide variable coupling with a range of Qext from 6x10⁶ to 6x10⁷ to allow flexibility to adjust to operating conditions of BESSY VSR. Here we present the RF design of the high-power coaxial coupler for BESSY VSR along with the design of the test stand for conditioning a pair of couplers.

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TUPAB012

Comparison of Prismatic and Circular Biperiodical Accelerating Structures of 27 GHz Operating Frequency

linac, simulation, impedance, alignment

1330

Yu.D. Kliuchevskaia, S.M. Polozov
MEPhI, Moscow, Russia

As known a biperiodical accelerating structure (BAS) represents as a system based on disk loaded waveguide (DLW) operating on Pi/2 mode and is widely used for the compact electron linacs. Earlier such structure with operating frequency of 27 GHz was proposed for medical application and beam dynamics simulations and electrodynamics modeling were done [1-2]. It was shown that such structure manufacturing should have very high accuracy and can be manufactured using electro erosive technology only. It is very complex for axi-symmetrical geometry to use such technology. Interesting option will to use a prismatic geometry BAS. In this report the design of a prismatic and disk-loaded BAS will discus, simulation results and analysis will presented.

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TUPAB043

Design and Simulation of Voltage Multiplier Column of a 300keV, 10mAParallel Fed Cockcroft Walton Electron Accelerator for Industrial Applications

simulation, electron, software, gun

1421

M. Nazari, F. Abbasi Davani, F. Ghasemi
Shahid Beheshti University, Tehran, Iran
S. Ahmadiannamin
ILSF, Tehran, Iran

In this article a 300keV, 10mA multiplier column has been designed for a parallel fed Cockcroft Walton electron accelerator for industrial applications. The parallel fed Cockcroft Walton multiplier is a capacitive coupling multiplier with diode rectification which can convert an input RF voltage to a low ripple output DC voltage. In this research tried to get a low ripple (300keV output) dc voltage. At first, the voltage multiplier column has been simulated with pspice simulation software. After doing the pspice simulations, optimum value of different parameters has been get. At the end we try to get the optimum values of pspice simulations with a mechanical design with CST STODIO. The mechanical design of voltage multiplier and its equivalent circuit hah a good accordance with each other.

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TUPAB045

Design and Construction of a Pre-Buncher for Iranian Low Energy Linear Accelerator

cavity, electron, linac, simulation

1428

S. Ahmadiannamin
ILSF, Tehran, Iran
M. Bahrami, M.R. Khalvati, M. Lamehi, H. Shaker, M. Shirshekan
IPM, Tehran, Iran

Iranian IPM low energy linear accelerator project (e-Linac) is in its final steps for commissioning. Beam dynamic simulations with and without Pre-buncher prior to buncher was done. The results represent improvement in capturing efficiency better than 25% by application of Pre-buncher cavity. In this paper, we present the simulation, construction, RF measurements and vacuum test results. After construction, we measured RF reflection coefficient better than -33 dB in the nominal frequency of 2997.9 MHz with quality factor of 4500.

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TUPAB136

Coupling and Polarization Control in a mm-wave Undulator

undulator, polarization, controls, electron

1647

F. Toufexis, J. Neilson, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
To reduce the linac energy required for an FEL radiating at a given wavelength, and hence its size, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling the electromagnetic fields while maintaining overmoded features for power handling capability and electron beam wakefield mitigation. We have designed a mm-wave undulator cavity at 91.392 GHz*. This undulator requires approximately 1.4 MW for sub-microsecond pulses to generate an equivalent K value of 0.1. Transferring such amounts of power in mm-wave frequencies requires overmoded corrugated waveguides, and coupling through irises creates excessive pulsed heating. We have designed a novel mode launcher that allows coupling power from a highly overmoded corrugated waveguide to the undulator through the beam pipe. Additionally, this mode launcher can be used along with grating polarizers to control the polarization of the produced light.
* F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.

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TUPIK021

Microwave Injection and Coupling Optimization in ECR and MDIS Ion Sources

plasma, ion, ion-source, ECRIS

1724

G. Torrisi, A.C. Caruso, G. Castro, L. Celona, S. Gammino, O. Leonardi, A. Longhitano, D. Mascali, E. Naselli, L. Neri, G. Sorbello
INFN/LNS, Catania, Italy
E. Naselli
Catania University, Catania, Italy
G. Sorbello
University of Catania, Catania, Italy

The fundamental aspect of coupling between microwave and plasma of the Electron Cyclotron Resonance Ion Source (ECRIS) and Microwave Discharge Ion Source (MDIS) is hereinafter treated together with ad hoc microwave-based plasma diagnostics, as a key element for the next progress and variations with respect to the classical ECR heating mechanism. The future challenges for the production of higher-charge states, higher beam intensity, and high absolute ionization efficiency also demand for the exploration of new heating schemes and synergy between experiments and modeling. An overview concerning microwave transport and coupling issues in plasma-based ion sources for particle accelerator will be given in the paper, along with perspectives for the design of next generation sources.

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TUPIK053

A Broadband Transverse Kicker Prototype for Intra-Bunch Feedback in the CERN SPS

kicker, impedance, simulation, feedback

1812

M. Wendt, I.A. Alonso Romero, S.J. Calvo, W. Höfle, O.R. Jones, E. Montesinos
CERN, Geneva, Switzerland

A transverse intra-bunch feedback system is currently under study at CERN for the SPS, to mitigate beam instabilities caused by electron clouds and coupled transverse modes (TMCI). This feedback system is designed for a bandwidth of 1 GHz, and based on a digital feedback controller and broadband power amplifiers. For the kicker, a periodic, quasi-TEM slotted transmission-line structure is foreseen which promises to meet the bandwidth requirements. This paper discusses the electromagnetic design and the mechanical implementation of a prototype kicker, demonstrating its performance and limitations based on numerical simulations.

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TUPIK099

Beam-Based Alignment for the Rebaselining of CLIC RTML

emittance, sextupole, quadrupole, alignment

1939

Y. Han, L. Ma
SDU, Shandong, People's Republic of China
A. Latina, D. Schulte
CERN, Geneva, Switzerland

The first stage of the CLIC is proposed to be at 380 GeV. So the Ring To Main Linac (RTML), which transport the beams from the damping ring to main linac with minimal emittance growth, should be restudied due to the new beam properties. In this paper the two bunch compressors in the RTML are redesigned. Then a complete study of the static beam-based alignment techniques along RTML is presented. The beam-based correction includes one-to-one and dispersion-free steering, then a global correction using tuning bumps is applied to reduce the final emittance and mitigate the effects of coupling. The results showed that the emittance growth budgets can be met both in the horizontal and vertical planes.

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TUPVA001

Progress on the Optics Corrections of FCC-hh

quadrupole, dipole, injection, lattice

2019

D. Boutin, A. Chancé, B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
B.J. Holzer, D. Schulte
CERN, Geneva, Switzerland

The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the three options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group, and the natural evolution of existing LHC. Studies are ongoing about the evaluation of the various magnets mechanical errors and field errors tolerances in the arc sections of FCC-hh, as well as an estimation of the correctors strengths necessary to perform the corrections of the errors. In this study advanced correction schemes for the residual orbit, the linear coupling and the ring tune are described. The impact of magnet tolerances on the residual errors, on the correctors technological choice and on the beam screen design are discussed. In particular the effect of the dipole a2 error is emphasized.

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TUPVA013

Lifetime of Asymmetric Colliding Beams in the LHC

simulation, luminosity, proton, ion

2067

J.M. Jowett, R. Alemany-Fernández, M.A. Jebramcik, T. Mertens, M. Schaumann
CERN, Geneva, Switzerland

In the 2013 proton-nucleus (p-Pb) run of the LHC, the lifetime of the lead beam was significantly shorter than could be accounted for by luminosity burn-off. These effects were observed at a lower level in 2016 and studied in more detail. The beams were not only asymmetric but the differences in the bunch filling schemes between protons and Pb nuclei led to a wide variety of beam-beam interaction sequences in the bunch trains. The colliding bunches were also of different sizes. We present an analysis of the data and an interpretation in terms of theoretical models.

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TUPVA031

Impact of Incoherent Effects on the Landau Stability Diagram at the LHC

octupole, betatron, damping, simulation

2125

C. Tambasco, J. Barranco García, X. Buffat, T. Pieloni
CERN, Geneva, Switzerland
J. Barranco García, X. Buffat, T. Pieloni
EPFL, Lausanne, Switzerland

Instability thresholds are explored at the Large Hadron Collider (LHC) by means of the computation of the Landau Stability Diagrams (SD). In the presence of diffusive mechanisms, caused by resonance excitations or noise, the SD can be reduced due to the modification of the particle distribution inside the beam. This effect can lead to a possible lack of Landau damping of the coherent modes previously damped by lying within the unperturbed SD area. The limitations deriving from coherent instabilities in the LHC is crucial in view of future projects that aim to increase the performance of the LHC such as the High-Luminosity upgrade (HL-LHC). Simulation tools for the computation of the SD have been extended in order to take into account the incoherent effects from long tracking through the detailed model of the accelerator machine. The model includes among others beam-beam interactions and octupoles and the interplay between both is addressed. Finally the simulation results are compared to the Beam Transfer Function (BTF) measurements in the LHC.

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TUPVA063

RF Tuning Tests on the Coupled FRANZ RFQ-IH-DTL

rfq, DTL, resonance, cavity

2224

A. Almomani, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Heilmann
GSI, Darmstadt, Germany

The neutron beam at the FRANZ facility will be produced by the 7Li(p, n)7Be reaction using an intense 2 MeV proton beam. These protons will be accelerated from 120 keV to 2 MeV by a coupled 4-Rod-type RFQ and a 8 gap interdigital H-type structure (IH-DTL). This coupled RFQ-IH-cavity will be operated at 175 MHz in cw mode and it has a total length of about 2.3 m. The two structures (RFQ, IH-DTL) are internally coupled inductively, and consequently only one RF-amplifier providing a total power up to 250 kW is needed for operation. The IH-DTL is RF tuned together with an Al-RFQ model, before final IH-DTL installation in the FRANZ cave, while the original RFQ was already installed in the beam line. After RF power and beam tests the coupled structure will be installed and continued with RF and beam. This paper will be focused on the RF tuning process and the main results will be presented.

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TUPVA064

Updated Cavities Design for the FAIR p-Linac

linac, cavity, proton, quadrupole

2227

A. Almomani, M. Busch, F.D. Dziuba, U. Ratzinger, R. Tiede
IAP, Frankfurt am Main, Germany
F.D. Dziuba, C.M. Kleffner
GSI, Darmstadt, Germany

The research program of antiproton beams for the FAIR facility requires a dedicated 68 MeV, 70 mA proton injector. This injector will consist of an RFQ followed by six room temperature Crossbar H-type CH-cavities operated at 325 MHz. The beam dynamics had been revised by IAP Frankfurt in collaboration with GSI-FAIR in Darmstadt to further optimize the design. This step was followed by cavity RF design. The detailed mechanical cavity design will begin in 2017, while the quadrupole lenses are under production already. In this paper, besides an overview the RF design of the coupled cavities with integrated focusing triplets will be a main focus.

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TUPVA069

Test of a High Power Room Temperature CH DTL Cavity

cavity, operation, impedance, DTL

2237

N.F. Petry, S. Huneck, K. Kümpel, H. Podlech, U. Ratzinger, M. Schwarz
IAP, Frankfurt am Main, Germany

The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) is planned to deliver ultra-short neutron pulses at high intensities and repetition rates. As part of FRANZ a 175 MHz room temperature 5-gap CH DTL cavity was designed and built. Its main task will be focusing the particle bunch longitudinally at 2 MeV particle energy. Furthermore the CH cavity can also be used to increase the energy as well as decrease it by 0.2 MeV. The rebuncher and its cooling system is optimized to work with a 5 kW amplifier. The amplification system is intended to provide continuous power (cw mode). Due to its operating parameters being nearly identical to the requirements of the MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) Project, experience for future cavity designs was gained. This includes considerations concerning cooling with use of a 12 kW amplifier. The recent results of conditioning and high power tests will be presented.

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TUPVA136

Using Sloppy Models for Constrained Emittance Minimization at the Cornell Electron Storage Ring (CESR)

emittance, lattice, storage-ring, simulation

2418

W.F. Bergan, A.C. Bartnik, I.V. Bazarov, H. He, D. L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.P. Sethna
Cornell University, Ithaca, New York, USA

Funding: DOE DE-SC0013571 NSF DGE-1144153
In order to minimize the emittance at the Cornell Electron Storage Ring (CESR), we measure and correct the orbit, dispersion, and transverse coupling of the beam.* However, this method is limited by finite measurement resolution of the dispersion, and so a new procedure must be used to further reduce the emittance due to dispersion. In order to achieve this, we use a method based upon the theory of sloppy models.** We use a model of the accelerator to create the Hessian matrix which encodes the effects of various corrector magnets on the vertical emittance. A singular value decomposition of this matrix yields the magnet combinations which have the greatest effect on the emittance. We can then adjust these magnet ‘‘knobs'' sequentially in order to decrease the dispersion and the emittance. We present here comparisons of the effectiveness of this procedure in both experiment and simulation using a variety of CESR lattices. We also discuss techniques to minimize changes to parameters we have already corrected.
* J. Shanks, D.L. Rubin, and D. Sagan, Phys. Rev. ST Accel. Beams 17, 044003 (2014).
** K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003).

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WEZB1

Review and Prospects of RF Solid State Amplifiers for Particle Accelerators

cavity, power-supply, booster, vacuum

2537

P. Marchand
SOLEIL, Gif-sur-Yvette, France

Thanks to the growth of high power semiconductor technology, solid state power amplifier (SSPA) systems with several hundred kW RF power are now available for various accelerator fields. Following the successful development at 352 MHz that took place at SOLEIL in the 2000s, the technology was transferred to industry and SSPAs at different frequencies, power levels, and pulse lengths have been widely adopted. In this paper we report about the SOLEIL experience with SSPAs and review the used or planned SSPAs in other accelerator facilities.

Slides WEZB1 [13.860 MB]

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WEPAB098

Dielectrically-Loaded Waveguide as a Microwave Undulator for High Brillance X-Rays at 45 - 90 Kev

undulator, brightness, photon, operation

2812

R. Kustom, A. Nassiri, G.J. Waldschmidt
ANL, Argonne, Illinois, USA

The HEM12 mode in a cylindrical, dielectrically-loaded waveguide provides E and H fields on the central axis that are significantly higher than the fields on the conducting walls. This structure, operating near the cutoff frequency of the HEM12 mode, spans a frequency range where the wavelength and phase velocity vary significantly. This property can be exploited to generate undulator action with short periods for the generation of high brightness x-rays. The frequency range of interest would be from 18 to 34.5-GHz. The goal would be to generate x-rays on the fundamental mode over a range of 45 to 90-kev. The tunability would be achieved by changing the source frequency while maintaining a constant on-axis equivalent undulator field strength of 0.5-T.

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WEPIK006

Cancellation of the Leak Field from Lambertson Septum for the Beam Abort System in the SuperKEKB

quadrupole, sextupole, emittance, septum

2918

N. Iida, M. Kikuchi, K. Kodama, T. Mimashi, T. Mori, Y. Ohnishi, K. Oide, H. Sugimoto, M. Tawada
KEK, Ibaraki, Japan

The first commissioning of SuperKEKB, Phase 1, was performed from February 2016 for five months. A Lambertson septum magnet is utilized to vertically extract the aborted beam, kicked by the horizontal abort kickers upstream into a beam dump. This magnet creates unexpected leak field with a non-negligible skew quadrupole component to the stored beam. Two kinds of skew quadrupole magnets are installed on both sides of the Lambertson septum. One is additional skew windings on the sextupole magnet, and the other is a skew quadrupole magnet with permanent magnets. This paper will report that the cancellations of the leak fields was successful and useful for optics correction.

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WEPIK067

Beam-Dynamics Simulation Studies for the HESR

dynamic-aperture, simulation, dipole, multipole

3084

J.H. Hetzel, U. Bechstedt, J. Böker, A. Lehrach, B. Lorentz, S. Quilitzsch, H. Soltner, R. Tölle
FZJ, Jülich, Germany
A. Lehrach
RWTH, Aachen, Germany

The High Energy Storage Ring (HESR) is part of the future Facility for Antiproton and Ion Research (FAIR) placed in Darmstadt (Germany). The HESR is designed for antiprotons with a momentum range from 1.5 GeV/c to 15 GeV/c, but will as well be suitable to provide heavy ion beams with a momentum range from approximately 0.6 GeV/c to 5.8 GeV/c. To guarantee smooth operation it is crucial to verify and to optimize the design with beam-dynamics simulations. Within recent studies* calculations based on a variant of the Lyapunov exponent were carried out to estimate the dynamic aperture. The studies could reproduce expected influences as reduced aperture due to tune resonances and tune shifts due to coupling. Thus they can be extended to investigate the dynamic behaviour of the beam and identify the main restrictions to the dynamic aperture near the chosen betatron tune. Furthermore ongoing measurements of the magnetic fields of the already produced bending dipoles and quadrupoles deliver a more precise insight to the harmonic content of these elements. Thus the existing simulations could now be updated by including the new measurement results.
*J. Hetzel, A. Lehrach, U. Bechstedt, J. Böker, B. Lorentz, R. Tölle: Towards Beam-Dynamics Simulations Including More Realistic Field Descriptions for the HESR, IPAC'16

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WEPIK089

Characterization of Resonant Impedances of CERN-SPS Gate Valves

impedance, simulation, resonance, vacuum

3139

T. Kaltenbacher, J. Repond, C. Vollinger
CERN, Geneva, Switzerland

For the CERN High Luminosity LHC project, a doubling of bunch intensity is foreseen. However, this intensity increase is currently limited by the LHC injector chain, in part due to longitudinal multi-bunch instabilities in the SPS. Therefore, the implementation of an accurate SPS impedance model was started some time ago in order to obtain a better understanding of instability sources and develop mitigation measures. In this paper, we present the electromagnetic characterization of commonly used all-metal gate valves with respect to their contribution to the SPS longitudinal impedance. The valve impedance was evaluated with commercially available EM-field simulation programs and verified with RF-bench measurements. Using this input, it was possible to obtain in particle simulations the dependence of the multi-bunch stability threshold on the number of these valves. A practical means of mitigation is to use a commercially available impedance shielded version of these gate valves. We also present the associated reduction in beam coupling impedance and the expected gain in beam stability if all existing unshielded valves are replaced by shielded valves.

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WEPIK090

Characterization of Shielding for the CERN-SPS Vacuum Flanges With Respect to Beam Coupling Impedance

impedance, shielding, vacuum, resonance

3143

T. Kaltenbacher, C. Vollinger
CERN, Geneva, Switzerland

Longitudinal multi-bunch instabilities in the CERN-SPS pose a serious limitation for future beam intensities required for high luminosity LHC. Hence, an impedance model for the SPS accelerator was developed from which one group of vacuum flanges could be identified as being a major culprit for these instabilities. These flanges support high impedance modes and their impact on beam stability was traced to a longitudinal mode at about 1.4GHz. For improvement of multi-bunch stability threshold, this group of flanges will be shielded as part of an impedance reduction campaign. We describe the evaluation of different impedance shielding designs proposed to reduce the longitudinal beam coupling impedance of this group of vacuum flanges in the SPS. EM-field simulations were performed to identify remaining resonances in these vacuum flanges with impedance shield prototypes installed, and the simulation models were benchmarked with RF-measurements. Depending on the performance and other parameters, the most suitable shield design will be selected, built and installed. As a first step, the installation of one shielding design in some positions in the SPS is planned for the beginning of 2017.

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WEPIK091

Amplitude Dependent Closest Tune Approach Generated by Normal and Skew Octupoles

octupole, simulation, resonance, injection

3147

E.H. Maclean, T. Persson, R. Tomás
CERN, Geneva, Switzerland

Amplitude dependent closest tune approach, an action dependent analogue of the DQmin generated by linear coupling, was observed in the LHC during Run1. It restricts the accessible resonance free area of the tune diagram and by altering tune spread has the potential to impact upon Landau damping. A theoretical description of such behaviour, generated by normal octupoles and linear coupling has recently been validated in the LHC, however simulation has established that amp-dependent closest approach may also be generated by a combination of normal and skew octupoles. This paper summarizes these simulation based observations.

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WEPIK092

Effect of Linear Coupling on Nonlinear Observables at the LHC

dynamic-aperture, injection, simulation, octupole

3151

E.H. Maclean, F.S. Carlier, M. Giovannozzi, T. Persson, R. Tomás
CERN, Geneva, Switzerland

Simulation work during LHC Run 1 established that linear coupling had a large impact on nonlinear observables such amplitude detuning and dynamic aperture. It is generally taken to be the largest single source of uncertainty in the modelling of the LHC's nonlinear single particle dynamics. Measurements in 2016 sought to confirm this impact of linear coupling with beam. This paper summarizes the observed influence of linear coupling on various nonlinear observables in the LHC.

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WEPIK095

Evaluation of Longitudinal Beam Impedance in the Beam Gas Ionization Monitor of the CERN-PS Accelerator

impedance, simulation, wakefield, detector

3163

N. Nasr Esfahani, T. Kaltenbacher, J.W. Storey, C. Vollinger
CERN, Geneva, Switzerland

The recently observed beam induced heating issues in the BGI monitors of the LHC which could have been occurred due to a strong coupling between the beam and the localized modes at the sensor location showed the general importance of a thorough evaluation of the beam coupling impedance and the corresponding heat deposit in beam monitoring equipments. This paper is devoted to the examination of the beam coupling impedance and beam induced heating for a currently under development beam gas ionization (BGI) monitor which is intended to be a part of the CERN Proton Synchrotron (PS) beam monitoring equipment. Details of the EM and wake field simulations for this BGI monitor together with the RF measurement results and power loss calculations will be presented.

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WEPIK096

Assessment of Beam Impedance for the CERN-PS Booster Wire Scanner

simulation, impedance, booster, proton

3167

T. Kaltenbacher, N. Nasr Esfahani, C. Vollinger
CERN, Geneva, Switzerland

It is well known that performance of accelerators critically depends on the interaction of high intensity beams with the surrounding structures. As a result of these beam interactions, it is required at CERN to characterize the beam coupling impedance of each new machine element that is to be installed in the accelerator ring. In the framework of the LIU (LHC Injectors Upgrade) project, a new design of rotational wire scanner to be used in the PS Booster is currently under development. As an intermediate step, the prototype of this wire scanner was evaluated with respect to its longitudinal beam coupling impedance. Depending on the performance of this machine element, it is planned to replace existing wire scanners in other machines at CERN (e.g. PS-Booster, PS and SPS) with very similar designs. This paper presents the simulations and describes the measurement methods used for benchmarking electromagnetic simulations performed for the impedance evaluation of the LIU wire scanner for the PS-Booster. Additionally, the device was fitted with an RF feed-through in order to monitor and attenuate certain undesired modes supported by this structure.

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WEPIK102

Measurement of RF Resonances and Measured Impact on Transverse Multibunch Instabilities from In-vacuum Insertions Devices

vacuum, resonance, damping, dipole

3188

G. Rehm
DLS, Oxfordshire, United Kingdom

Diamond Light Source has currently 15 in-vacuum insertion devices (ID) installed, mostly built in-house. Their measured impact on multi-bunch mode damping as a result of varying magnet gap was shown before, now we augment these with measurements of broadband frequency spectra with stored beam obtained using an antenna placed in the ID vacuum. Finally, we present off-line measurements of resonances in the ID vessel acquired using a vector network analyser and two antennae installed in-vacuum.

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WEPIK109

Experimental Study of Vertical-Longitudinal Coupling Induced by Wakefields at CesrTA

wakefield, lattice, simulation, electron

3200

S. Wang, J.D. Perrin, S. Poprocki, D. L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by NSF PHY-1416318, PHYS-1068662
Transverse vertical wakefields can cause vertical beam size growth in accelerators. Here we report recent measurements and simulations of wakefields from movable scrapers at the CesrTA. The charge dependent vertical beam size growth was observed while a single scraper was inserted through the top of the chamber. No change in the beam size was observed with top and bottom scrapers inserted symmetrically. The apparent growth in the vertical beam size was due in large part to the y-z coupling (vertical crabbing) induced by the monopole wake of the asymmetric scraper configuration. We explored this y-z coupling by varying vertical betatron phase advance between the vertical beam size monitor and the scrapers. In addition, we found that existing residual, current independent y-z coupling could be compensated by the scraper wake. Predictions of a tracking simulation are in good agreement with the measurements.

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WEPIK111

Derivation of a Finite Element Formulation From a Lagrangian for the Electromagnetic Potentials

electromagnetic-fields, operation, resonance, interface

3208

A.R. Vrielink, M.H. Nasr, S.G. Tantawi
SLAC, Menlo Park, California, USA

Conventional electromagnetic finite element solvers typically solve a weak formulation of the Helmholtz wave equation. While mathematically this approach is correct, it does not fully reflect the fundamental physics involved. We offer an alternative variational formulation which is not derived from the Helmholtz wave equation but is more fundamentally tied to the physics of the system: a Lagrangian for the electromagnetic potentials. Solving for the potentials directly allows for a natural accounting of the beam wave interaction. It could also potentially avoid the issue of deleterious spurious modes inherent when selecting the Coulomb gauge and enforcing the subsequent divergence free condition, eliminating the need for vector basis functions. Herein we present the theory and the resulting formulation including a discussion on gauge fixing. We conclude with some numerical results demonstrating the potential of this formulation.

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WEPVA055

Pre Orbit Correction Based on Tunnel Level Measurement in SuperKEKB

alignment, optics, factory, emittance

3385

A. Morita, H. Koiso, Y. Ohnishi, H. Sugimoto
KEK, Ibaraki, Japan

The SuperKEKB accelerator tunnel has about 30mm displacement in the vertical direction. From the result of optics correction simulation with the tunnel displacement, it was decided that the beamline components align against the smoothed line of the measured tunnel level in order to save the alignment cost and time. In order to compensate the large tunnel displacement, the pre orbit correction based on the tunnel level measurement is applied at the beginning of the phase-1 commissioning, and the beam circulation is achieved with the small number of magnet adjustments. We report the result of the pre orbit correction.

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WEPVA094

Study of an Improved Beam Screen Design for the LHC Injection Kicker Magnet for HL-LHC

impedance, kicker, injection, simulation

3471

V. Vlachodimitropoulos, M.J. Barnes, L. Ducimetière, L. Vega Cid, W.J.M. Weterings
CERN, Geneva, Switzerland

During Run 1 of the LHC, one of the injection kicker magnets (MKIs) occasionally exhibited an excessively high ferrite temperature, caused by coupling of the high intensity beam to the real impedance of the magnet. Beam-screen upgrades have been very effective in reducing beam coupling impedance during Run 2. However, temperature measurements during LHC operation have shown that one end of the MKIs ferrite yoke is consistently hotter than the other: this effect is due to highly non-uniform beam induced power deposition along the kicker. Electromagnetic and thermal simulations show that part of the ferrite yoke will be above its Curie temperature when the LHC is operated with HL-LHC beam parameters, which could increase the turn-around time between fills of the LHC. An impedance mitigation study is presented in this paper with emphasis on the effect of the beam screen layout upon both total beam induced power deposition and its longitudinal distribution. Results of complex thermal simulations, to benchmark the effectiveness of the proposed schemes, are reported. To validate the proposed modification a test bench measurement was performed and preliminary results are discussed

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WEPVA095

Preliminary Estimate of Beam Induced Power Deposition in a FCC-hh Injection Kicker Magnet

kicker, impedance, injection, collider

3475

A. Chmielinska, M.J. Barnes, W. Bartmann, F. Burkart, B. Goddard
CERN, Geneva, Switzerland
A. Chmielinska
EPFL, Lausanne, Switzerland

The Future Circular Collider for hadrons (FCC-hh) will require a fast injection kicker system that is highly reliable and that does not limit accelerator performance. Important considerations in the design of such a system are machine protection constraints, collider filling factor and hence rise and fall times of the kicker magnet field. Fast rise time kicker magnets are generally ferrite loaded transmission line type magnets with a rectangular shaped aperture. The beam coupling impedance of the kicker magnets is crucial, as this can be a dominant contribution to beam instabilities. In addition, beam-induced heating of the ferrite yoke due to the real component of the longitudinal beam coupling impedance needs to be controlled: if the ferrite temperature exceeds the Curie point this impacts the ability to inject beam and hence the availability of the machine. This paper presents estimates for the beam induced power deposition in the ferrite yoke, based on a calculated FCC beam spectrum and an analytical model of longitudinal impedance for unshielded kicker magnets.

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WEPVA101

Review of Stripline Beam Impedance: Application to the Extraction Kicker for the CLIC Damping Rings

impedance, simulation, kicker, extraction

3499

C. Belver-Aguilar, M.J. Barnes
CERN, Geneva, Switzerland

The beam coupling impedance of the stripline kicker for beam extraction from the CLIC Damping Rings (DRs) has been studied analytically, numerically with CST Particle Studio (PS) and measured in the laboratory, although not all the results were understood. In order to have a better knowledge about the beam coupling impedance of a stripline kicker, a simple model has been first studied, with flat electrodes and a cylindrical beam pipe. From this preliminary study, a new approach for the dipolar component of the horizontal impedance has been derived, when considering both odd and even operating modes of the striplines. This new approach has been used to understand the differences found between the predicted transverse impedance and the two wire measurements carried out in the laboratory for the prototype CLIC DR striplines. Future tests of beam coupling impedance with beam in the ALBA Synchrotron Ligth Source will complete this study.

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WEPVA128

The Data Acquisition System and Inspection Equipment on Vibration Evaluation for Deionized and Cooling Water Pumps in TPS

status, operation, data-acquisition, alignment

3568

Y.-H. Liu, Y.-C. Chung, C.K. Kuan, Z.-D. Tsai
NSRRC, Hsinchu, Taiwan

The purpose of this paper is to evaluate the vibration amplitude and spectrum for TPS water pump systems. The utility systems operate continuously since 2014, some of deionized and cooling water pumps produced higher vibration amplitude and noise during operation. The possibly reason could be poor system accuracy, inappropriate installation and commission adjustment. The data acquisition system on vibration evaluation for deionizes water pumps was established in 2016. Accord-ing to the long-tern vibration amplitude recording, the system operational status could be clarified. After vibra-tion test for several months, the bearing of booster deion-ized water pump was found abrasive since coupling be-tween motor and pump misaligned. Besides, the founda-tion of copper deionized water pump system was broken and observed by rapidly increase vibration amplitude in short term. The water pump systems were repaired and maintained base on vibration evaluation. There is still some remain problems for deionized and cooling water pump systems. The utility systems could prevent mal-function through regular vibration inspection and daily data acquisition.

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THPAB020

Coupling Impedances and Collective Effects for FCC-ee

impedance, vacuum, collective-effects, collider

3734

E. Belli, M. Migliorati
University of Rome La Sapienza, Rome, Italy
G. Castorina, B. Spataro, M. Zobov
INFN/LNF, Frascati (Roma), Italy
A. Novokhatski
SLAC, Menlo Park, California, USA
S. Persichelli
LBNL, Berkeley, California, USA

A very important issue for the Future Circular Collider (FCC) is represented by collective effects due to the self-induced electromagnetic fields, which, acting back on the beam, could produce dangerous instabilities. In this paper we will focus our work on the FCC electron-positron machine: in particular we will study some important sources of wake fields, their coupling impedances and the impact on the beam dynamics. We will also discuss longitudinal and transverse instability thresholds, both for single bunch and multibunch, and indicate some ways to mitigate such instabilities.

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THPAB032

Estimates of Collective Effects in the HALS Storage Ring Having the First Version Lattice

emittance, impedance, storage-ring, lattice

3770

N. Hu, Z.H. Bai, W. Li, Q. Luo, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

The Hefei Advanced Light Source (HALS) is a diffraction-limited storage ring with a beam energy of 2.0 GeV. Recently the first version lattice has been designed for the HALS storage ring, and the natural emittance is about 18 pm·rad. In this paper, we study the collective effects in this storage ring, including calculations of intra-beam scattering effect and Touschek lifetime, and estimates of the thresholds of some single-bunch and multi-bunch instabilities.

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THPAB040

Destabilising Effect of Linear Coupling in the LHC

simulation, damping, octupole, operation

3791

L.R. Carver, D. Amorim, N. Biancacci, X. Buffat, K.S.B. Li, E. Métral, B. Salvant, M. Schenk
CERN, Geneva, Switzerland

During operation in 2015 and 2016, some transverse instabilities were observed when either the coupling (or closest tune approach) C- was large, or when the tunes were moved closer together. This motivated a campaign of simulations on the effect of linear coupling on the transverse stability. Measurements made during operation and with dedicated beam time have been found to confirm the predictions. This paper will detail the results of the linear coupling studies and relate them to operation of the LHC in the future.

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THPAB046

SixTrack for Cleaning Studies: 2017 Updates

collimation, ion, scattering, collider

3811

A. Mereghetti, R. Bruce, F. Cerutti, R. De Maria, A. Ferrari, M. Fiascaris, P.D. Hermes, D. Mirarchi, P.G. Ortega, D. Pastor Sinuela, E. Quaranta, S. Redaelli, K.N. Sjobak, V. Vlachoudis
CERN, Geneva, Switzerland
J. Molson
LAL, Orsay, France
Y. Zou
IHEP, Beijing, People's Republic of China

SixTrack is a single particle tracking code for simulating beam dynamics in ultra-relativistic accelerators. It is widely used at the European Organisation for Nuclear Research (CERN) for predicting dynamic aperture and cleaning inefficiency in large circular machines like the Super Proton Synchrotron (SPS), the Large Hadron Collider (LHC) and the Future Circular Collider (FCC). The code is under continuous development, to both extend its physics models, and enhance performance. The present work gives an overview of developments, specifically aimed at extending the code capabilities for cleaning studies. They mainly involve: the online aperture check; the possibility to perform simulations coupled to advanced Monte Carlo codes like Fluka or using the scattering event generator of the Merlin code; the generalisation of tracking maps to ion species; the implementation of composite materials of relevance for the future upgrades of the LHC collimators; the physics of interactions with bent crystals. Plans to merge these functionalities into a single version of the SixTrack code will be outlined.

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THPAB047

New Features of the 2017 SixTrack Release

simulation, electron, collimation, HOM

3815

K.N. Sjobak, J. Barranco García, R. De Maria, E. McIntosh, A. Mereghetti
CERN, Geneva, Switzerland
M. Fitterer
Fermilab, Batavia, Illinois, USA
V. Gupta
IIT, Guwahati, Assam, India
J. Molson
LAL, Orsay, France

The SixTrack particle tracking code is routinely used to simulate particle trajectories in high energy circular machines like the LHC and FCC, and is deployed for massive simulation campaigns on CERN clusters and on the BOINC platform within the LHC@Home volunteering computing project. The 2017 release brings many upgrades that improve flexibility, performance, and accuracy. This paper describes the new modules for wire- and electron lenses (WIRE and ELEN), the expert interface for beam-beam element (BEAM/EXPERT), the extension of the number of simultaneously tracked particles, the new Frequency Map Analysis (FMA) postprocessing option, the generation of a single zip of selected output files (ZIPF) in order to extend the coverage of the studies in LHC@HOME (e.g. FMA and on-line aperture checks), coupling to external codes (DYNK-PIPE and BDEX), a new CMAKE based build- and test mechanism, and internal restructuring.

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THPAB056

Dynamic Aperture Studies of the Long-Range Beam-Beam Interaction at the LHC

simulation, emittance, luminosity, dynamic-aperture

3840

M.P. Crouch, R.B. Appleby
UMAN, Manchester, United Kingdom
J. Barranco García, T. Pieloni, C. Tambasco
EPFL, Lausanne, Switzerland
X. Buffat, M. Giovannozzi, E.H. Maclean
CERN, Geneva, Switzerland
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Long-range beam-beam interactions dictate the choice of operational parameters for the LHC, such as the crossing angle and β^* and therefore the luminosity reach for the collider. These effects can lead to particle losses, closed orbit effects and emittance growth. Defining how these effects depend on the beam-beam separation will determine the minimum crossing angle and the β^* the LHC can operate. In this article, analysis from a dedicated machine study is presented in which the crossing angle was reduced in steps and the impact on beam intensity and luminosity lifetimes were observed. Based on the observations during the machine study, the intensity decays are compared to expectations from models. Estimates of the luminosity reach in the LHC are also computed.

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THPAB079

Terahertz Chirper for the Bunch Compression of Ultra-Low Emittance Beams

emittance, electron, dipole, laser

3899

A.R. Vrielink, A. Marinelli, E.A. Nanni
SLAC, Menlo Park, California, USA

Recent efforts have demonstrated the possibility of achieving ultralow transverse emittance beams for high brightness light sources and free electron lasers*. While these lower emittances should translate to improved lasing efficiency and higher peak brightness in FELs, these beams are commensurately more vulnerable to coherent synchrotron radiation (CSR) for the selfsame reasons. Conserving these ultralow emittances through the bunch compressors in an FEL given their increased propensity to emit CSR is particularly challenging. We investigate the possibility of imposing a large energy chirp at terahertz wavelengths to reduce the required magnetic fields in the compressor, counteracting the ultralow emittance in the generation of CSR. A second, higher frequency THz chirper would then be used to dechirp the beam after the chicane. Operation at THz as opposed to conventional radiofrequencies offers significantly larger chirp at similar input powers, yet still with wavelengths greater than typical FEL bunch lengths (several femtoseconds). Potential experimental schemes will be suggested in the context of LCLS and their feasibility evaluated.
* S. Bettoni, M. Pedrozzi and S. Reiche, Phys. Rev. ST Accel. Beams. 18, 123403 (December, 2015).

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THPAB095

Detuning Compensation in SC Cavities Using Kalman Filters

cavity, controls, FPGA, operation

3938

A. Ushakov, P. Echevarria, A. Neumann
HZB, Berlin, Germany

For CW driven superconducting cavities operating at small bandwidth, like in ERL or FEL light sources, it is mandatory to precisely control any source of detuning. Therefore, a Kalman [1] filter based approach was developed and implemented as FPGA firmware to act as the core part of a detuning compensation algorithm. It relies on a fit by a second order model to a measured transfer function of cavity's forced oscillations with damping, caused by piezo drives and data about observed current phase with some adjustable confidence rate. The initial data for this core is taken from field detection firmware on mTCA.4's SIS8300-L2 digitizer, transferred by low latency links to a carrier board equipped by piezo drive controller where the DSP processing by the Kalman algorithm performed. The processing is characterized by a 550 kHz rate in pipeline mode and occupies almost all DSP resources of the Spartan 6 FPGA chip. The experimental results of detuning compensating technique applied to a SC photoinjector cavity are presented in this contribution.
Kalman, R. E. (1960): A New Approach to Linear Filtering and Prediction Problems, Transaction of the ASME, Journal of Basic Engineering, Pages 35-45.

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THPAB110

Custom Optomechanics for the Optical Synchronization System at the European XFEL

laser, timing, alignment, FEL

3976

F. Zummack, M. Felber, C. Gerth, T. Lamb, J.M. Müller, M. Schäfer, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany

Free-electron-lasers like the upcoming European XFEL demand highly reliable optical synchronization in range of few femtoseconds. The well known optical synchronization system at FLASH had to be re-engineered to meet XFEL requirements comprising demands like ten times larger lengths and raised numbers of optically synchronized instruments. These requirements directly convert to optomechanical precision and have yielded in a specialized design accounting for economical manufacturing technologies. These efforts resulted in reduced spatial dimensions, improved optical repeatability, maintainability and even reduced production costs. To account for thermal influences the heart of the optical synchronization system is based on an optical table made out of SuperInvar. To fully exploit its excellent thermal expansion coefficient, mechanical details need to be taken into account. This work presents the design and its realization of the re-engineered optomechanical parts of the optical synchronization system, comprising mounting techniques, link stabilization units and optical delay lines for high drift suppression.

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THPAB111

Sub-Femtosecond Jitter Ultra High Performance Oscillators for Accelerator Timing

controls, cavity, electron, impedance

3979

A. Gronefeld
Ingenieurbüro Gronefeld, Herten, Germany

Extremely stable RF-Sources are at the heart of Electron Beam Accelerators and impact beam quality and beam energy. Jitter requirements on those sources are very tight and linked to the quest of ever decreasing (XFEL) laser pulse length, currently in the tens of femtoseconds. For the Pohang Accelerator Laboratory in Pohang/Korea, a 2.856GHz phase-lockable oscillator with a jitter performance of 0.8fS (10kHz..10MHz) was developed and deployed, together with a master oscillator that supplies rubidium-stabilized 476MHz for synchronization. In terms of phase noise, these 2.856GHz oscillators exhibit -125dBc/Hz@1kHz, -145dBc/Hz@10kHz and -165dBc/Hz@100kHz offset, while reaching a noise floor of -180dBc/Hz. Using the same technology of a dielectric resonator oscillator, a 3.9GHz source was developed for the European XFEL at DESY/Hamburg, achieving 0.3fS (10kHz/10MHz). Phase noise is down to -125dBc/Hz@1kHz, -155dBc/Hz@10kHz and -175dBc/Hz@100kHz offset, with a noise floor of -180dBc/Hz. The strategy of designing ultra low phase-noise sources with dielectric resonators is outlined, and challenges and limitations within the oscillator design, but also measurement technology are presented.

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THPAB127

Development of 1.3 GHz Cavity Combiner for 24 kW CW SSA

cavity, simulation, linac, electromagnetic-fields

4020

W. Liu, B. Du, G. Huang, L. Lin, L. Shang, W.B. Song
USTC/NSRL, Hefei, Anhui, People's Republic of China

The 24KW CW SSA (Solid-State Amplifier) is being developed to drive the 1.3GHz SC Linac used in a THz light source. The SSA adopts the compact all-in-one combining method ' cavity combiner, which is proposed and developed in recent years. This paper reports the R&D of the cavity combiner. The cavity combiner resonates in TM010 mode, coupling with 24 coaxial-connected 1kW amplifier modules. The cavity's electromagnetic characteristic is calculated by CST, and the mechanical structure including the input and output coupler has been designed.

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THPAB151

Online Optimisation Applications at SPS

injection, storage-ring, sextupole, quadrupole

4086

T. Pulampong, P. Klysubun, S. Kongtawong, S. Krainara, P. Sudmuang
SLRI, Nakhon Ratchasima, Thailand

Optimisation of a particle accelerator with very limited diagnostic system is proved to be very challenging and complicated. Theoretical calculation and perfect machine model never guarantee the best solution in the actual machine. In this work, optimisation of injection system from Low energy Beam Transport line (LBT) to Siam Photon Source (SPS) storage ring and reduction of beam coupling employing Robust Conjugate Direction Search (RCDS) algorithm are demonstrated. New record improvement on injection efficiency and better coupling control will be presented.

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THPIK015

Prototype Results of the ESR Barrier-Bucket System

cavity, impedance, accumulation, injection

4133

M. Frey, P. Hülsmann, H. Klingbeil
GSI, Darmstadt, Germany
D. Domont-Yankulova, K. Groß, J. Harzheim, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany

The experimental storage ring (ESR), operated at the GSI facility in Darmstadt, Germany, allows experiments with a variety of ion species. In combination with the existing electron cooler, its RF cavities have been used to demonstrate longitudinal beam accumulation in order to increase the beam intensity. Limitations of the existing narrow-band cavities led to the development of a magnetic alloy (MA) based broad-band cavity for the generation of Barrier-Bucket signals. The application of a pre-distortion method demands high linearity of the driver amplifier and highlights the importance of its selection process. In this contribution, the cavity and amplifier system design is described and data measured at a prototype system are presented.

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THPIK017

Field Uniformity Preservation Strategies for the ESS DTL: Approach and Simulations

DTL, simulation, linac, drift-tube-linac

4139

G.S. Mauro, F. Grespan, A. Palmieri, A. Pisent
INFN/LNL, Legnaro (PD), Italy
P. Mereu, M. Mezzano, C. Mingioni, M. Nenni
INFN-Torino, Torino, Italy

The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4 % (3 ms pulse length, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. This paper presents the approach taken in order to preserve field flatness of DTL Tanks. This strategy required a set of simulations and consequent choices about RF design of DTL cells, RF coupler tuning and compensation, cooling of the DTL cells. Outcomes of these simulations and the experimental verifications of this approach are then explained.

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THPIK035

Rf Properties of a 175 MHz High-Q Load Circuit

rfq, operation, linac, vacuum

4169

S. Maebara, M. Sugimoto
QST, Aomori, Japan

For an RF input coupler test, a 175MHz high-Q load circuit based on a 6 1/8 in. co-axial waveguide was developed. This circuit consists of the RF input coupler, a trombone-type phase shifter and a stub tuner. The coupler with a loop antenna and the stub tuner are located in edges of the circuit, the loop antenna and the tuner work for a short plate. When RF input power is injected into the circuit, a high-voltage standing wave is excited by adjusting the tuner. The power of standing wave required for the tests is also accumulated due to its low resistive loss. At the operation frequency of 175 MHz, the resistive loss of 0.046ohm is measured and an equivalent RF power of 200 kW is accumulated by the RF input power of 740 W. In this circuit, the bandwidth is narrow to be ±5 kHz in S11 parameter of less -20 dB, but the equivalent RF power of 200 kW-14 sec CW could be achieved after sufficient RF aging. Using this high-Q load circuit, all the fabricated 9 couplers were successfully tested for RF contact defects, unnecessary low-Q value and extraordinary outgassing. This article describes these RF properties in detail.

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THPIK043

Design and Optimization of a 2MeV X-Band Side Coupled Accelerating Structure

impedance, simulation, linac, beam-loading

4193

H. Yuan
IHEP, Beijing, People's Republic of China

An X-band bi-period side-coupled accelerating structure has been designed in this paper. The structure's working frequency is 9.3GHz. '/2 mode is chosen for the structure's stability. There are 11 accelerating cells, the first 5 work as non-light velocity part while the other 6 work as light velocity part. After CST simulation, the coupling constant between accelerating cells and coupling cells is 5%, efficient shunt impedance is 142M'/m. For the beam dynamic analysis, the particle energy is selected to be 2 MeV and the peak current is 60 mA for the radiation dosage limits by national standard. After Pamela optimization, the particle's capture efficiency is more than 30%. To feed power into the structure, a coupler is designed in the middle of the structure and the coupling coefficient is 1.4. The structure is manufactured and the measurement result accords well with designing value.

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THPIK046

Design, Fabrication and Cold Test of a C-Band Barrel Open Cavity Pulse Compressor

cavity, klystron, simulation, vacuum

4200

S. Shu
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
M. Hou, S. Pei, N.B. Song, J.R. Zhang, F. Zhao
IHEP, Beijing, People's Republic of China

The first prototype of the C band barrel open cavity (BOC) pulse compressor has been manufactured by the Institute of High Energy Physics (IHEP), Beijing, which is used to test the brazing process and the RF properties of the structure at low power. The whispering gallery mode TM6, 1,1 with an unload Q of 100, 000 was adopt to oscillate in the cavity, and the coupling factor was optimized to achieve the highest power gain. This paper mainly deals with the RF design, mechanical design and cold test of the C band BOC pulse compressor.

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THPIK050

Measurement and Tuning of the RF Field for the CSNS DTL

DTL, cavity, operation, experiment

4210

A.H. Li, M.X. Fan, B. Li, J. Peng, P.H. Qu, Y. Wang, X.L. Wu
CSNS, Guangdong Province, People's Republic of China
Q. Chen, S. Fu, K.Y. Gong, H.C. Liu
IHEP, Beijing, People's Republic of China

The CSNS DTL accelerates negative hydrogen ions from 3MeV to 80MeV with resonant frequency of 324MHz and peak current of 15mA. The CSNS includes four DTL cavities with diameter of 56.6cm and each length of 9 meters. RF properties research and measurement have been done to make sure the design and manufacture validate for beam operation. A new automatic system has been developed for measuring field distribution. The secondary derivation method is used to calculate the amount of the tuners to tune axial field flatness. The tilt of TS curve is used to judge the gap between the post couplers and drift tubes to achieve stability. At last the tanks have good flatness and strong stabilization, the field deviation is 2% with the standard deviation of 0.96%, and the maximum TS parameter is 65%/MHz. After the low power RF tuning experiment, the four tans have been installed in the tunnel, and have gotten good results of high power test and beam acceleration experiment.

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THPIK054

The X-Band Pulse Compressor for Tsinghua Thomson Scattering X-Ray Source

cavity, simulation, klystron, scattering

4214

Y.L. Jiang, H.B. Chen, C. Cheng, W. Gai, J. Shi, P. Wang, X.W. Wu, H. Zha
TUB, Beijing, People's Republic of China

An X-band (11.424 GHz) high-power RF station is being built for Tsinghua Thomson scattering X-ray Source (TTX). The station aims to feed several X-band accelerating structures working at a high gradient of 80 MV/m. An X-band pulse compressor is designed to compress the RF pulse from 1.5 us to 100 ns and to generate more than 250 MW peak power from a 50MW klystron. This pulse compressor implements a resonate cavity housing the HE11-mode as the energy storage cavity, with a high quality factor Q of more than 10⁵. The detailed design of the high-Q cavity as well as the dedicate couplers of this pulse compressor are present in this work.

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THPIK055

Power-Conditioning Cavity Design and Measurement of the Coaxial Coupler for the Injector of XiPAF Project

cavity, rfq, vacuum, DTL

4218

Y. Lei, X. Guan, W. Wang, X.W. Wang, Q.Z. Xing, H.Y. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China

For the RF high power conditioning on coaxial power couplers of the XiPAF (Xi'an Proton Application Facility), the RF high power-conditioning cavity was designed and manufactured. The cavity consists of a rectangular reso-nant cavity with two ports, which one is connected with input coupler from RF power source and the other one is connected with output coupler, and a tuner. The tuning frequency range could cover 325 (+0.5, -9.5) MHz. The measured Q factors are matched with the design results generally. But the S-parameter is not ideal compared to the simulation. This paper will present the design and low power measurement results of the cavity

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THPIK058

Development of a S-Band Pulse Compressor

cavity, klystron, linac, laser

4227

P. Wang, H.B. Chen, C. Cheng, J. Shi, X.W. Wu, H. Zha
TUB, Beijing, People's Republic of China

We designed and fabricated a pulse compressor for S-band high power test stand at Tsinghua University. This pulse compressor is made up of a sphere resonant cavity with quality factor of 100000 and a rf polarizer. It has the ability of compressing a pulse from 3.6 us to 300 ns with the power gain of 7. A short description of the pulse compressor is presented, together with the RF design and low level RF measurement.

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THPIK067

A C-Band Compact Spherical RF Pulse Compressor for the SXFEL Linac Energy Upgrade

cavity, electron, simulation, linac

4248

Z.B. Li, W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A new compact C-band (5712 MHz) spherical RF pulse compressor has been designed for Shanghai Soft X-ray Free Electron Laser (SXFEL) facility energy upgrading at Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences (CAS). This pulse compressor contains one high Q0 spherical RF resonant cavity which works on two TE113 modes and a novel coupler. As there is only one storage cavity, this pulse compressor can be much smaller than the traditional SLED. With the coupling coefficient 4.9, the average power gain can be as high as 3.8. In this paper, the scheme of the C-band spherical pulse compressor and RF design are presented.

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THPIK117

High Efficiency High Power Resonant Cavity Amplifier for Accelerator Applications

cavity, operation, impedance, network

4374

M.P.J. Gaudreau, D.B. Cope, E.G. Johnson, M.K. Kempkes, J. Kinross-Wright, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: Work supported by US Department of Energy under contract DE-SC0015780
Diversified Technologies, Inc. (DTI) has designed and built a unique integrated resonant-cavity combined solid-state amplifier. The design radically simplifies solid-state transmitters to create favorable and straightforward scaling to high power levels. A crucial innovation is demonstration of an inherently reliable soft-failure mode of operation; a failure in one or several of these myriad combined transistors has negligible performance impact. In addition, this design couples the transistor drains directly to the cavity without first transforming to 50 Ohms, avoiding the otherwise-necessary multitude of circulators, cables, and connectors. A conventional amplifier has a complete set of electrical and cooling connections for every stage, resulting in many hundreds of connections for a high power transmitter'in some DTI designs, there are as few as four. This construction both reduces the cost and increases the power level at which it is cost-effective to employ a solid-state transmitter. The prototype has demonstrated multiple-transistor combining from 300 MHz to 1300 MHz, at powers up to 5 kW. This prototype is scalable to several hundred kW at these frequencies.

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THPIK118

Final Assembly and Testing of MICE RF Modules at LBNL

vacuum, cavity, low-level-rf, HOM

4377

T.H. Luo, A.R. Lambert, D. Li, S.P. Virostek, J.G. Wallig
LBNL, Berkeley, California, USA
T.G. Anderson, A.D. Bross, D.W. Peterson
Fermilab, Batavia, Illinois, USA
M.A. Palmer
BNL, Upton, Long Island, New York, USA
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

Funding: Work supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231
The international Muon Ionization Cooling Experiment aims to demonstrate the transverse cooling of a muon beam by ionization interaction with absorbers and re-acceleration in RF cavities. The final MICE cooling channel configuration has two RF modules, each housing a 201 MHz RF cavity to compensate the longitudinal energy loss in the absorbers. Two RF modules have been assembled and tested at LBNL. This paper reports the final assembly work, as well as the vacuum test and low level RF measurements.

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THPVA021

Dynamics of Spectator Particles in Space-Charge Fields of Mismatched Beams With Cross-Plane Coupling

space-charge, lattice, simulation, proton

4462

M. Holz, V.G. Ziemann
Uppsala University, Uppsala, Sweden

In accelerators with high beam power, even moderate beam losses must be avoided. These losses are due to particles reaching large transverse amplitudes that form a low density halo orbiting the beam core. To study the beam halo formation, we place a spectator particle outside the beam core and let it interact with the core's electric field. The core, we model by a self-consistent transverse Gaussian beam including non-linear space charge forces and cross-plane coupling.

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THPVA029

Study of Single Bunch Instabilities with Transverse Feedback at Diamond

feedback, operation, storage-ring, controls

4489

E. Koukovini-Platia, R. Bartolini, A.F.D. Morgan, G. Rehm
DLS, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom

Single bunch instability studies have been carried out at Diamond with and without the transverse multi-bunch feedback (TMBF) system. Single bunch instability thresholds were measured for zero, positive and negative chromaticity values by increasing the current till the instability onset. The bunch-by-bunch feedback system was then used to suppress the motion of the bunch centroid and the new thresholds were measured in all chromaticity regimes. The feedback loop phase of the TMBF was changed from resistive to reactive as well as intermediate to find the optimal feedback settings that maximize the single bunch instability thresholds.

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THPVA034

Comparison of the Coupling of Dipole Motion From Bunch to Bunch in an Electron Beam Caused by Electron Clouds at CesrTA Due to Variations in Bunch Length and Chromaticity

electron, damping, positron, dipole

4509

M.G. Billing, L.Y. Bartnik, J.A. Crittenden, M.J. Forster, N.T. Rider, J.P. Shanks, M.B. Spiegel, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
R. Holtzapple
CalPoly, San Luis Obispo, California, USA
E.C. Runburg
University of Notre Dame, Indiana, USA

Earlier experiments at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) have probed the interaction of the electron cloud (EC) with a 2.1 GeV stored positron beam. Since a very low EC density is expected with the electron bunches, these results characterize the dependence of beam-vacuum chamber impedance interactions, which are common to both positron and electron beams. The experiments were performed on a 30-bunch electron train with a 14 ns spacing, at a fixed current of 0.75mA/bunch, at two different vertical chromaticity settings and for four different bunch lengths (or synchrotron tunes.) The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 20 turn-by-turn beam position monitors in CESR to measure the correlated bunch-by-bunch dipole motion and 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 analysis of the observations from these experiments and compare them with effects of the EC on the positron beam's dipole motion and coupling of the motion from each bunch to its succeeding bunches.

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THPVA088

DESIGN AND CONSTRUCTION OF BRAZED SIDE COUPLED CAVITY OF MEDICAL ACCELERATOR

simulation, cavity, vacuum, electron

4664

S. Ahmadiannamin, Kh.S. Sarhadi
ILSF, Tehran, Iran
F. Abbasi, M. Mohseni Kejani
Shahid Beheshti University, Tehran, Iran
M. Bahrami, M. Lamehi
IPM, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
S. Zarei
Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran

Two types of standing wave RF cavities are used routinely in construction of medical linear accelerators. These two types are Side coupled and on-axis coupled standing wave cavities. This selection is based on higher shunt impedance and compactness in comparison to travelling wave RF cavities. In this paper, we present the simulation, construction and measurement results of brazed section of 3 GHz side coupled RF cavity. It is the first successful experience of its kind in Iran. The obtained experiences can be used effectively for construction of side coupled thermionic RF guns and RF cavities of medical or industrial linacs.

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THPVA105

A Novel Side Coupling Standing-Wave Accelerating Structure for a Medical Linac

cavity, electron, impedance, linac

4710

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

A novel side coupling standing-wave (SW) accelerat-ing tube for low energy medical linac has been designed that operating frequency is 2998 MHz, operating mode is ', final energy is 6 MeV and beam current is 130 mA. A novel bridge hole between an accelerating cavity and coupling cavity has been utilized to reduce the mutual effect between two cavities and improve the anti-jamming capability and the long term stability. The inner end plate of the inlet of the first accelerating cavity in-cludes the nose cone to realize self-focusing in transverse to improve the beam quality. The simulation of the elec-tromagnetic field of structure and beam dynamic has been carried out with the SUPERFISH, CST Microwave studio and Parmela, respectively.

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THPVA109

Design and Fuild-Solid-Heat Coupling Analysis of an Electrostatic Deflector for Hust SCC250 Proton Therapy Facility

septum, proton, cyclotron, extraction

4713

S. Hu, K. Fan, L.X.F. Li, Z.Y. Mei, Z.J. Zeng, L.G. Zhang
HUST, Wuhan, People's Republic of China

The study of proton therapy equipment has earned more and more attention in recent years in China. A superconducting cyclotron based proton therapy facility is being developed for/at Huazhong University of Science and Technology (HUST). The proton beam is extracted by means of electrostatic deflectors followed by a series of magnetic channels. This paper introduces the design of an electrostatic deflector, including the structure optimization and the material selections. In order to minimize the risk of destruction caused by the proton beam loss, fluid-solid-heat coupling analysis for the deflector has been conducted by applying computational fluid dynamics (CFD) on ANSYS 16.0 software. The maximum temperatures of the septum in various cases of cooling water speed, septum thickness and material have been investigated respectively. The result based on thermal analysis will give us a valuable reference to choose a suitable configuration for the deflector.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA109

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THPVA125

Status of Commissioning of Gantry 3 at the PSI PROSCAN Facility

operation, interface, controls, proton

4744

A. Koschik, J.P. Duppich, M. Eichin, P. Fernandez Carmona, A. Gerbershagen, A.L. Lomax, D. Meer, S. Safai, J.M. Schippers, D.C. Weber
PSI, Villigen PSI, Switzerland

Paul Scherrer Institute currently extends its PROSCAN facility with a third gantry treatment room - Gantry 3, which is realized in a research collaboration with Varian Medical Systems. The main research goals at the PROSCAN facility include further development of precise spot scanning and optimized beam delivery with low dead-time for treatment of moving targets. Consequently Gantry 3 is designed to feature advanced pencil beam scanning technology with a large scan field size of 30x40cm, integrated cone beam CT functionality and will in the future allow fast energy layer switching. The main challenge in realizing Gantry 3 is the integration of the Varian Gantry into the existing PROSCAN control system environment, allowing seamless beam operation. Installation of the additional treatment room has started in summer 2015 followed by the integration and technical commissioning phases of the Gantry in 2016, all during full operation of the existing treatment areas at our facility. We report about the special challenges and achieved performance results during commissioning of the Varian Gantry system in combination with the PSI PROSCAN facility.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA125

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THPVA146

Robust Linac Platform for Wide Replacement of Radioactive Sources

vacuum, linac, impedance, simulation

4805

A.V. Smirnov, M.A. Harrison, A.Y. Murokh, A.Yu. Smirnov
RadiaBeam Systems, Santa Monica, California, USA
R.B. Agustsson, S. Boucher, T.J. Campese, J.J. Hartzell, K.J. Hoyt
RadiaBeam, Santa Monica, California, USA
E.A. Savin
MEPhI, Moscow, Russia

Funding: This work was supported by the U.S. Department of Energy (awards No. DE-SC-FOA-0011370).
To improve public security and prevent the diversion of radioactive material for Radiation Dispersion Devices, development of an inexpensive, portable, easy-to-manufacture linac system is very important. Tubular structure with parallel pairs of rods crossed at 90 degrees suggests as high as 36% inter-cell coupling due to inherent compensation along with still substantial shunt impedance. Simultaneously it offers simplified brazing process and may dramatically simplify tuning of the entire structure. A novel design of a multi-cell, single-section, X-band structure for replacement of Ir192 source is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA146

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FRYBA1

From Niels Bohr to Quantum Computing

operation, controls, electron, factory

4852

K. Mølmer
AU, Aarhus, Denmark

The development and use of accelerators for research has been closely linked to an era of modern physics which of course includes quantum mechanics. Niels Bohr was one of the foreground figures in the development of quantum mechanics and the IPAC community would like to recognise his contributions to this field in 2017, when IPAC takes place in Copenhagen, where he was active. Quantum computing is a subject of enormous potential and interest, and we would like to hear about the historical links to Niels Bohr and the so called Copenhagen School of Quantum Mechanics, and what we realistically can expect from this development.

Slides FRYBA1 [2.490 MB]

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