IPAC2017 - List of Keywords (impedance)

Paper	Title	Other Keywords	Page
MOPAB006	Design and Prototyping of New CERN Collimators in the Framework of the LHC Injector Upgrade (LIU) Project and the High-Luminosity (HL-LHC) Project	collimation, dipole, proton, vacuum	80
	F.-X. Nuiry, O. Aberle, M. Bergeret, A. Bertarelli, N. Biancacci, R. Bruce, M. Calviani, F. Carra, A. Dallocchio, L. Gentini, S.S. Gilardoni, R. Illan Fiastre, I. Lamas Garcia, A. Masi, A. Perillo-Marcone, S. Pianese, S. Redaelli, E. Rigutto, B. Salvant CERN, Geneva, Switzerland
	In the framework of the Large Hadron Collider (LHC) Injectors Upgrade (LIU) and the High-Luminosity LHC (HL-LHC) Projects at CERN (European Organization for Nuclear Research, in Geneva, Switzerland), collimators in the Super Proton Synchrotron (SPS) to LHC transfer lines as well as ring collimators in the LHC will undergo important upgrades in the forthcoming years, mainly focused during the Long Shutdown 2 foreseen during 2019-2020. This contribution will detail the current design of the TCDIL collimators with a particular emphasis on the engineering developments performed on the collimator jaws, aiming at getting a stringent flatness while consid-ering also the integration of thermal shock resistant materials. The prototyping phase done at CERN will be also described. The activities ongoing to prepare the series production for other LHC collimator types (TCPPM, TCSPM, TCTPM, TCLD) will be presented, describing the role that each of these collimators play on the HL-LHC Project. A focus on the series production processes, the manufacturing and assembly technologies involved and the quality and performance assurance tests will be given.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB006
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB022	Fabrication Studies of a 650 MHz Superconducting RF Deflecting Mode Cavity for the ARIEL Electron Linac	cavity, niobium, electron, linac	120
	D.W. Storey, R.E. Laxdal, B. Matheson, N. Muller TRIUMF, Vancouver, Canada D.W. Storey Victoria University, Victoria, B.C., Canada
	A 650 MHz RF deflecting mode cavity is required for the ARIEL electron Linac to separate interleaved beams bound for either rare isotope production or a recirculation loop containing a Free Electron Laser. An RF separator will allow both modes to run simultaneously by imparting opposite transverse deflection to adjacent bunches at 1.3 GHz. The SRF cavity has been designed to provide up to 0.6 MV transverse voltage for operation with up to a 50 MeV CW electron beam. The design was optimised for compact geometry with high shunt impedance. Due to the low dissipated power, the cavity will operate at 4 K and allows for investigations into low cost fabrication techniques. The cavity is being machined from bulk reactor grade ingot Niobium and welds will be performed using TIG welding in an ultra-pure Argon chamber. Results of fabrication studies will be presented as well as measurements performed on a copper prototype cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB022
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB052	A Transverse Deflection Structure with Dielectric-Lined Waveguides in the Sub-THz Regime	electron, simulation, emittance, laser	215
	F. Lemery University of Hamburg, Hamburg, Germany R.W. Aßmann, K. Flöttmann, T. Vinatier DESY, Hamburg, Germany
	Longitudinal bunch measurements are typically done with rf-powered transverse deflection structures with operating frequencies 1-12~GHz. We explore the use of mm-scale, THz-driven, dielectric-lined cylindrical waveguides as transverse deflectors by driving the fundamental deflecting mode of the structure, the HEM₁₁. We give a brief overview of the physics, history, and provide an example with a 5~MeV beam using {\sc astra} and {\sc CST-MWS}. This work was supported by the European Research Council (ERC) under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant agreement no. 609920
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB052
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB071	A Beam Position Monitor for the Diagnostic Line in MEBT2 of J-PARC Linac	diagnostics, linac, pick-up, operation	281
	A. Miura, Y. Kawane, J. Tamura JAEA/J-PARC, Tokai-mura, Japan T. Miyao KEK, Ibaraki, Japan
	In the linac of the Japan Proton Accelerator Research Complex (J-PARC), the neutral hydrogen (H⁰) generation from the negative hydrogen ion (H⁻) beam is one of key issues to mitigate the beam loss. In order to diagnose the H⁰ particles, we installed the bump magnets to make a chicane orbit of the H⁻ beam. To evaluate the horizontal shifts of the beam orbit, a beam position monitor (BPM) is fabricated. The BPM measures the shift-positions with various driving currents of the bump magnets. We employed the WSM to measure the H⁻ beam profile. It also help us to compare the shift-positions measured by BPM. In this paper, the design and the performance of the BPM is described. In addition, we describe how to compare the shift position.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB071
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB113	Usage of the Transverse Damper Observation Box for High Sampling Rate Transverse Position Data in the LHC	injection, diagnostics, pick-up, operation	389
	L.R. Carver, X. Buffat, A.C. Butterworth, W. Höfle, G. Iadarola, G. Kotzian, K.S.B. Li, E. Métral, M. Ojeda Sandonís, M.E. Söderén, D. Valuch CERN, Geneva, Switzerland
	The transverse damper observation box (ADTObsBox) is a device that makes accessible the bunch-by-bunch turn-by-turn data recorded from the pickups of the LHC transverse damper. This device can provide online transient analysis of different beam dynamics effects (tunes and damping times at injection, for example), while also under development is an online coherent instability triggering system. This paper will provide an overview of the current setup and plans for future upgrades, as well as detailing how it deals with the large volume of data being generated. The results of some analysis that rely on the ADTObsBox will also be shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB113
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB152	Precise Synchronous Phase Measurements	storage-ring, synchrotron, synchrotron-radiation, radiation	487
	W.X. Cheng, B. Bacha, K. Ha, O. Singh BNL, Upton, Long Island, New York, USA
	Funding: DOE contract No: DE-SC0012704 Precise measurements of storage ring synchronous phase helps to understand the machine impedance and improve the high current performance. We present different methods tested at NSLS-II, including the streak camera measurement, relative phase measurement from a high sampling frequency oscilloscope by comparing the beam signal and reference signal. Both streak camera and scope method have high precision to measure the synchronous phase (<1ps). Other methods to measure the synchronous phase include the I-Q detection from BPM electronics, FPM scope have been tested as well. We have used these systems to study the synchronous phase shift at different beam current, RF voltages and ID gaps. Recent results will be presented and discussed in the paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB152
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPIK013	Design and Simulation of a C-Band Photocathode RF Gun With a Coaxial Coupler for UEM	gun, electron, cavity, coupling	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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPIK043	Beam-Based Waveform Measurements of the CERN PS Injection Kicker	kicker, flattop, injection, timing	603
	V. Forte, W. Bartmann, J.C.C.M. Borburgh, L.M.C. Feliciano, A. Ferrero Colomo, M.A. Fraser, T. Kramer, L. Sermeus CERN, Geneva, Switzerland
	In the framework of the LHC Injectors Upgrade (LIU) project, a beam-based technique has been developed for measuring the waveform the CERN Proton Synchrotron (PS) horizontal injection kicker, named KFA45. The technique avoids the need for tedious magnetic measurements, especially when a spare magnet is presently unavailable and measuring the operational magnet with a magnetic field probe is complicated by integration reasons. In this paper, the technique and results of the waveform measurements are summarised. The results already provide additional information in terms of waveform characterisation for the validation of numerical simulations and are of great interest for the future LIU performance upgrade.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK043
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPVA034	A Compact EUV Light Source Using a mm-Wave Undulator	undulator, electron, gun, quadrupole	928
	F. Toufexis, V.A. Dolgashev, C. Limborg-Deprey, 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. We are building an Extreme Ultra Violet (EUV) light source based on a 1.75 mm period RF undulator. We will use a thermionic X-Band injector which utilizes RF bunch compression. The beam is accelerated using an X-Band traveling wave accelerating structure followed by a high shunt impedance standing wave accelerating structure up to 129 MeV. The beam then goes through a 91.392 GHz RF undulator with a period of 1.75 mm, producing EUV radiation around 13.5 nm. The RF undulator is powered by a 91.392 GHz decelerating structure, which extracts the RF power from the spent electron beam. The length of the entire beam line from the cathode to the beam dump is approximately 6 m. We describe the design and projected operating parameters for this EUV light source. 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-MOPVA034
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPVA080	HOM Simulations and Damping Scheme for CEPC Cavities	HOM, cavity, damping, collider	1052
	H.J. Zheng, J. Gao, F. Meng, P. Sha, J.Y. Zhai IHEP, Beijing, People's Republic of China
	In this paper, it will be presented that the higher order mode (HOM) analysis of the 650 MHz cavities for the Circular Electron-Positron Collider (CEPC). The higher order modes excited by the intense beam bunches must be damped to avoid additional cryogenic loss and multi-bunch instabilities. To keep the beam stable, the impedance budget and the HOM damping requirement are given. The conventional coaxial HOM coupler, which will be mounted on the beam pipe, is planned to extract the HOM power below the cut-off frequency of the beam pipe, and the propagating modes will be absorbed by the two HOM absorbers at room temperature outside the cryomodule.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA080
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPVA141	Input RF Coupler Design for Energy Compensator Cavity in eRHIC	cavity, simulation, radiation, synchrotron	1184
	C. Xu, S. Bellavia, I. Ben-Zvi, M. Blaskiewicz, Y. Hao, K.S. Smith, R. Than, A. Zaltsman BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. This report gives a detail design of a 1.3 GHz input coupler for second harmonic cavity for eRHIC project. This coupler is designed to transmit 200KW CW RF to the cavity to compensate the synchrotron radiation loss. This report include RF and thermal simulation for this design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA141
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB012	Comparison of Prismatic and Circular Biperiodical Accelerating Structures of 27 GHz Operating Frequency	coupling, linac, simulation, 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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB070	S-Band Accelerating Structure for High-Gradient Upgrade of TTX	electron, simulation, accelerating-gradient, linac	1485
	D.Z. Cao, H.B. Chen, Y.-C. Du, W. Gai, W.-H. Huang, X.C. Meng, J. Shi, C.-X. Tang, X.W. Wu, H. Zha TUB, Beijing, People's Republic of China
	Thomson scattering x-ray source is an indispensable scientific X-ray imaging tool in various research fields. The 3-meter S-band linac in Tsinghua Thomson scatter-ing X-ray source (TTX) has been running at an accelerat-ing gradient of 15 MV/m so far. The gradient will be upgraded to 30MV/m by replacing the old structure with a shorter linac. Detailed optimization of the RF design of the new S-band linac structure is presented in this paper. Finally, further research on energy upgrade with X-band structures are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB070
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB082	Research of L-Band Disk-Loaded Waveguides Travelling Wave Accelerating Structures for a High Power Linac	cavity, bunching, electron, network	1506
	Y.M. Zhang USTC, SNST, Anhui, People's Republic of China Y.J. Pei, L.S. Sheng, Y. Song USTC/NSRL, Hefei, Anhui, People's Republic of China
	L-band Electron Accelerator is widely used for industrial irradiation. This paper describes a constant-impedance, disk-loaded structure operating on the 2Pi/3 mode. The design details of L-band travelling wave accelerating structures are presented. All RF parameters in metal disk-loaded waveguides and fields were calculated. The SUPERFISH code was used to design the bunching and accelerating cavities. At the same time, we also calculated the beam dynamics. Some model cavities have been fabricated and experimental studies were carried on. In this study, some valuable results were obtained, which can provide a beneficial datum for the design and manufacture of L-band travelling-wave accelerating structures of 50MeV LINAC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB082
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB121	Bench Measurements and Beam Tests of a Prototype Stripline Kicker for Swap-Out Injection in the ALS-U	kicker, vacuum, injection, alignment	1599
	S. De Santis, J.M. Byrd, T.H. Luo, G.C. Pappas, C. Steier, C.A. Swenson, W.L. Waldron LBNL, Berkeley, California, USA
	Funding: Work supported by the the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS upgrade to a diffraction-limited light source (ALS-U Project) relies on a swap-out injection scheme, where the circulating current is maintained constant by injecting on-axis fresh bunch trains, replacing old trains, which are simultaneously extracted. The realization of a stripline kicker to perform such an operation presents several challenges in terms of optimal matching to the pulser, contributions to the beam coupling impedance, and dissipation of the power deposited by the stored beam. To test our design choices for the ALS-U kicker, we have built and installed on the ALS a kicker with characteristics similar to the design for the ALS-U, as the more challenging aspects of the project are concerned. In particular, while the small distance between stripline electrodes reduces the required pulser voltage, the extreme proximity of the circulating beam requires a careful evaluation of the interaction between beam and kicker. In this paper we present the first measurements with beam, after the test kicker installation, together with the results of bench measurements performed on a cold model and computer simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB121
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB132	A Novel Dual-Mode Dual-Frequency Linac Design	operation, cavity, network, distributed	1634
	M.H. Nasr, S.G. Tantawi SLAC, Menlo Park, California, USA
	In this paper we will present a new type of accelerator structure that operates simultaneously at two accelerating modes with two frequencies. The frequencies are not harmonically related, but rather have a common sub-harmonic. This design will use a recently developed parallel-feeding network that feeds every cavity cell independently using a distributed feeding network. This will overcome many of the practical complications of coupled cell structure. We will provide the theoretical background for our dual-mode design as well as present our optimized design that operates at C and X bands simultaneously and provides enhanced gradient and efficiency compared to single-mode designs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB132
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB143	Dependence of LEReC Beam Energy Spread on Photocathode Laser Modulation	laser, electron, space-charge, flattop	1669
	S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, M.G. Minty, B. Sheehy, Z. Zhao BNL, Upton, Long Island, New York, USA B. Sheehy Sheehy Scientific Consulting, Wading River, New York, USA
	Present requirements to the photocathode DC gun of the low energy RHIC electron cooling (LEReC) project is to produce 100 ps long bunch of electrons with 130 pC charge. The laser pulse of required length will be produced with the stacking of multiple few picosecond long sub-pulses. Depending on the choice of the laser sub-pulse length and on the relative delay between these sub-pulses one can obtain laser pulse with various longitudinal intensity modulations. The longitudinal modulation of laser intensity creates longitudinal modulation of electron bunch charge. Such modulation is known to cause the growth of e-beam uncorrelated energy spread in photoinjectors - the effect we would like to avoid. In this paper we estimate growth of e-beam energy spread due to its initial density modulation and set requirements to the maximum allowable depth of longitudinal modulation of photocathode laser intensity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB143
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB148	Investigation of a Splitring-RFQ for High Current Ion Beams at Low Frequencies	rfq, resonance, simulation, ion	1680
	M. Baschke, H. Podlech, A. Schempp IAP, Frankfurt am Main, Germany
	For hadron linacs RFQs are the first stage of acceleration. To reach high intensities a new Splitring-RFQ is investigated. Not only a high current and high beam quality/brilliance should be achieved, also a good tuning flexibility and comfort for maintenance are part of the study. It will consist of two stages with 27 MHz and 54 MHz to accelerate ions with an A/q of 60 up to energies of 200 keV/u. Therefor RF simulations with CST MWS were done to study the quality factor and the shunt impedance as well as tuning possibilities. First results and the status of the project will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB148
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK053	A Broadband Transverse Kicker Prototype for Intra-Bunch Feedback in the CERN SPS	kicker, simulation, feedback, coupling	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK053
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK093	Sensitivity of the LHC Transverse Feedback System to Intra-Bunch Motion	feedback, pick-up, simulation, hardware	1916
	G. Kotzian, W. Höfle, D. Valuch CERN, Geneva, Switzerland
	The LHC Transverse Feedback System is designed to damp and counteract all possible coupled bunch modes between the lowest betatron frequency and 20 MHz. The present study reveals that the analogue frontend processing scheme based on down converting the pick-up signal at the LHC RF frequency to baseband considerably extends the detected bunch movements visible to the feedback system to beyond 1 GHz. We develop an analytical model of the signal processing chain to explore the impact of even-symmetric and odd-symmetric intra-bunch movements on the detected beam position as a function of the longitudinal bunch shape. A set of equations is derived suitable for numerical simulations, or as a complement in particle tracking codes to further refine the behaviour of the LHC transverse feedback system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK093
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK105	The Design Improvement of Horizontal Stripline Kicker in TPS Storage Ring	kicker, storage-ring, vacuum, operation	1961
	P.J. Chou, C.K. Chan, C.-C. Chang, K.T. Hsu, K.H. Hu, C.K. Kuan, I.C. Sheng NSRRC, Hsinchu, Taiwan
	We plan to replace the existing horizontal stripline kicker of the transverse feedback system with an improved design. Large reflected power was observed at the downstream port of stripline kicker driven by the feedback amplifier. A rapid surge of vacuum pressure was observed when we tested the high current operation in TPS storage ring in April 2016. A burned feedthrough of the horizontal stripline kicker was discovered during a maintenance shutdown. The improved design is targeted to reduce the reflection of driving power from feedback system and to reduce beam induced RF heating. This major modification of the design is described. The results of RF simulation performed with the electromagnetic code GdfidL are reported as well.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK105
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK122	Bunch-by-Bunch Feedback Kickers for SPEAR3	kicker, feedback, ion, vacuum	2012
	K. Tian, W.J. Corbett, J.D. Fox, S.M. Gierman, R.O. Hettel, X. Huang, A.K. Krasnykh, N. Kurita, D.J. Martin, J.A. Safranek, J.J. Sebek SLAC, Menlo Park, California, USA Q. Lin DongHua University, Songjiang, People's Republic of China D. Teytelman Dimtel, San Jose, USA
	SPEAR3 operates with a large cross-section copper vacuum chamber, mode-damped RF cavities and low-impedance insertion devices. As a result, the beam is passively stable for 280-bunch circulating beam current up to 500ma when the background gas pressure is low. In the future, more small-gap insertion devices will be installed and plans are underway to implement resonant bunch-crabbing for the ultrafast x-ray research program. These requirements drive the need for a fast, bunch-by-bunch feedback system to control beam instabilities, remove unwanted satellite bunches and resonantly crab select bunches on demand. In this paper we present a conceptual design for the transverse bunch-by-bunch stripline kickers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK122
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA019	Impact and Mitigation of Electron Cloud Effects in the Operation of the Large Hadron Collider	electron, cryogenics, operation, injection	2085
	G. Iadarola, B. Bradu, P. Dijkstal, L. Mether, G. Rumolo CERN, Geneva, Switzerland
	In 2015 and in 2016 the Large Hadron Collider has been routinely operated with 25 ns bunch spacing. With this beam configuration electron clouds develop in a large fraction of the beam chambers, in spite of a very large electron dose accumulated on the surfaces. This posed several challenges to different aspects of the beam operation. In particular, the machine settings had to be optimized in order to mitigate coherent and incoherent effects of the electron cloud on the beam dynamics while a specifically designed feed-forward control had to be implemented and optimized in order to dynamically adapt the regulations of the cryogenic system to the strong heat load deposited by the electron cloud on the beam screens of the cryogenic magnets. At the same time, the data collected from the different accelerator subsystems (heat loads, vacuum pressures, evolution of the bunch by bunch beam parameters) allowed to significantly improve our models and understanding on these phenomena.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA068	The New Injector Design for MYRRHA	cavity, simulation, emittance, rfq	2234
	K. Kümpel, P. Müller, D. Mäder, N.F. Petry, H. Podlech IAP, Frankfurt am Main, Germany
	The MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) Project is a planned accelerator driven system (ADS) for the transmutation of long-living radioactive waste. A critical passage for the beam quality and especially for the emittance is the injector. Therefore, a new injector design with improved beam dynamics has been developed, featuring low emittance growth rates while using only room temperature structures. The previous design consisted of a 4-Rod RFQ, 7 room temperature and 5 superconducting CH-DTL cavities and 2 rebuncher cavities, whereas the superconducting cavities in the new design have been replaced by 8 room temperature CHs and an additional rebuncher. The main challenge during the development is achieving the required reliability to reduce the thermal stress inside the planned reactor. Therefore, simulations with CST MICROWAVE STUDIO have been made to compare several cooling concepts and to optimize the cavities, especially in terms of the shunt impedance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA068
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA069	Test of a High Power Room Temperature CH DTL Cavity	cavity, operation, coupling, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA069
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA080	Stochastic Cooling Hardware for Low Energy Deuterons at COSY	pick-up, kicker, experiment, electron	2261
	B. Breitkreutz, R. Greven, N. Shurkhno, R. Stassen, H. Stockhorst FZJ, Jülich, Germany
	One of the central utilizations of the COSY facility nowadays is to host experiments for the JEDI (Jülich Electric Dipole moment Investigations) collaboration. These experiments use polarized deuteron beams at momenta below 1 GeV/c, that are stored for several minutes. In order to increase the spin coherence time, beam cooling is necessary. Electron cooling is applied to pre-cool the beam, but the solenoids of the electron cooler may not be perfectly compensated. Thus, stochastic cooling would be desirable instead. Unfortunately, the existing stochastic cooling system is not sensitive at low beam velocities. This paper presents newly developed stochastic cooling pickups and kickers for a system dedicated to low beam velocities of approximately 0.5c. The design is based on the slot-ring type pickups that have been developed for the High Energy Storage Ring (HESR), but optimized for low particle velocities and a low frequency band of 350-700 MHz. Since the structures get much bigger in comparison to the HESR version, mechanical properties must be reconsidered and a trade-off between electrical properties, cooling performance and constructability must be found.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA080
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA085	First Experiences with HESR Stochastic Cooling System	kicker, pick-up, hardware, ion	2278
	R. Stassen, B. Breitkreutz, T. Katayama, N. Shurkhno, H. Stockhorst FZJ, Jülich, Germany T. Katayama Nihon University, Narashino, Chiba, Japan L. Thorndahl CERN, Geneva, Switzerland
	The stochastic cooling system of the HESR (High Energy Storage Ring) is based on completely new structures especially designed for the HESR. Each beam surrounding slot of these so called slot-ring couplers covers the whole image current without a reduction of the HESR aperture and without any plunging system. One pickup and one kicker have been already fabricated and installed into the COSY ring to demonstrate stochastic cooling in all three dimensions with only one structure. First results of commissioning with proton beams will be presented. The longitudinal cooling system at HESR is based on filter cooling with an optical notch-filter and ToF cooling. The demanding accuracy concerning phase stability requires dedicated control of the notch-frequency. The optical COSY filter has been modified and can be proven in long term runs together with the new stochastic cooling system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA085
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA092	An Upgrade Scenario of RF System to Achieve 1.6 MW Beam Acceleration in J-PARC RCS	cavity, power-supply, resonance, acceleration	2297
	M. Yamamoto, M. Nomura, T. Shimada, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	The J-PARC RCS has successfully accelerated 1 MW equivalent proton beam. However, the beam commissioning results and the particle tracking simulation suggest that the RCS has possibility to accelerate up to 1.6 MW beam. Since the power supply of the rf system almost reaches the limit under the condition of 1 MW beam, we consider the possible upgrade scenario of the rf system to accelerate 1.6 MW beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA092
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA094	Beam Dynamics Design of the Muon Linac High-Beta Section	linac, simulation, emittance, target	2304
	Y. Kondo, K. Hasegawa JAEA/J-PARC, Tokai-mura, Japan R. Kitamura University of Tokyo, Tokyo, Japan T. Mibe, M. Otani, M. Yoshida KEK, Tsukuba, Japan
	Funding: This work was supported by JSPS KAKENHI Grant Number 16H03987. A muon linac development for a new muon g-2 experiment is now going on at J-PARC. Muons from the muon beam line (H-line) at the J-PARC MLF are once stopped in an silica aerojel target and room temperature muoniums are evaporated from the aerogel. They are dissociated with laser (ultra slow muons), then accelerated up to 212 MeV using a linear accelerator. For the accelerating structure from 40 MeV, disk-loaded traveling-wave structure is applicable because the particle beta is more than 0.7. The structure itself is similar to that for electron linacs, however, the cell length should be harmonic to the increase of the particle velocity. In this paper, the beam dynamics design of this muon linac using the disk-loaded structure is described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA094
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEOAB3	RF Quadrupole Structures for Transverse Landau Damping in Circular Accelerators	quadrupole, damping, simulation, collider	2516
	M. Schenk, X. Buffat, L.R. Carver, A. Grudiev, K.S.B. Li, E. Métral, K. Papke CERN, Geneva, Switzerland A. Maillard ENS, Paris, France
	The beams required for the high luminosity upgrade of the Large Hadron Collider (HL-LHC) and other potential future circular colliders (FCC) call for efficient mechanisms to suppress transverse collective instabilities. In addition to octupole magnets installed for the purpose of Landau damping in the transverse planes, we propose to use radio frequency (rf) quadrupole structures to considerably enhance the aforementioned stabilising effect. By means of the PyHEADTAIL macroparticle tracking code as well as analytical studies, the stabilising mechanism introduced by an rf quadrupole is studied and explained. It is, furthermore, compared to the influence of the second order chromaticity on transverse beam stability.
	Slides WEOAB3 [2.537 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOAB3
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB115	Normal Conducting CW Transverse Crab Cavity For Producing Short Pulses In SPEAR3	cavity, HOM, damping, photon	2840
	Z. Li, V.A. Dolgashev, M. Dunham, K.J. Gaffney, R.O. Hettel, X. Huang, N. Kurita, J.A. Safranek, J.J. Sebek, K. Tian SLAC, Menlo Park, California, USA
	Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515. The ability to produce short pulse X-rays on the scale of 1-10 ps fwhm in the SPEAR3 storage ring light source would enable enhanced timing mode studies of dynamic processes in materials as they occur. The crab cavity approach appears to be optimal for SPEAR3 to produce short pulse X-rays. Furthermore, by using a two-frequency crabbing scheme, SPEAR3 would be able to produce short-pulse bunches while supplying the high average flux needed for regular users. While supercon-ducting RF (SCRF) technology could be a natural choice for the CW crab cavity, the deflecting voltage for SPEAR3 crabbing appears to be within reach of more affordable normal conducting RF (NCRF). In this paper, we present a preliminary NCRF CW crab cavity design for SPEAR3.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB115
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK009	Collimators for SuperKEKB Main Ring	background, factory, positron, HOM	2929
	T. Ishibashi, Y. Suetsugu, S. Terui KEK, Ibaraki, Japan
	SuperKEKB, which is an upgrade project of KEKB, is an electron-positron collider with extremely high luminosity. Collimators (movable masks) for SuperKEKB have been designed to fit an antechamber scheme of the vacuum system and will be operated to improve backgrounds in the particle detector named Belle II. We are developing two types of collimators; a horizontal and vertical collimator. The collimator has a pair of horizontally or vertically opposed movable jaws with RF fingers. Each jaw travels independently through 5-25 mm horizontally or 2-12 mm vertically in a distance between the beam axis and the tip of the jaw. SuperKEKB will operate with high currents of short bunch lengths, therefore it is important to estimate and decrease the impedance of the collimators. Two horizontal collimators were already installed in the positron ring and operated during Phase-1 commissioning for approximately 5 months, from February to June 2016. In this presentation, the latest design, and the results in the Phase-1 commissioning are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK009
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK014	Coupled Bunch Instability and Its Cure at J-PARC RCS	kicker, space-charge, emittance, injection	2946
	Y. Shobuda, H. Harada, H. Hotchi, P.K. Saha, T. Takayanagi, F. Tamura, N. Tani, T. Togashi, Y. Watanabe, K. Yamamoto, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y.H. Chin, Y. Irie, T. Toyama KEK, Ibaraki, Japan
	The RCS at J-PARC is a kicker-impedance dominant machine, which violates the impedance budget from a classical viewpoint. Nevertheless, we have recently succeeded to accelerate a 1-MW equivalent beam by making maximum use of the space charge effect on the beam instabilities. In this report, we explain the manipulation to suppress the beam instability, at first. Then, we discuss some issues to suppress the beam instabilities for beams with much smaller transverse emittance, as well as the present status of our efforts to reduce the kicker impedance toward the realization of the higher beam power at the RCS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK014
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK054	Evaluation and Attenuation of Sirius Components Impedance	HOM, dipole, storage-ring, vacuum	3048
	H.O.C. Duarte, L. Liu, S.R. Marques LNLS, Campinas, Brazil
	The Sirius in-vacuum components have their design improvements, possibilities and choices presented, where wake heating, single-bunch and multi-bunch effects and mechanical aspects were taken into account. The results were finally evaluated and added to the Sirius impedance budget.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK054
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK055	Analysis and Countermeasures of Wakefield Heat Losses for Sirius	HOM, simulation, vacuum, storage-ring	3052
	H.O.C. Duarte, L. Liu, S.R. Marques, T.M. da Rocha, F.H. de Sá LNLS, Campinas, Brazil
	Design evaluation and possible solutions for several in-vacuum components of Sirius are presented, having their impedance analysis focused on mitigating the wake heating impact. Thermal and/or structural simulation of the models are carried out by considering the heat load directly obtained from wakefield simulations with resistive wall boundary conditions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK055
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK058	Preliminary Longitudinal Impedance Model for the ESRF-EBS	vacuum, simulation, undulator, storage-ring	3063
	S.M. White ESRF, Grenoble, France
	In light sources, longitudinal beam coupling impedance can deteriorate performance through bunch lengthening or increased longitudinal emittance due to the microwave instability. Simulation estimates are therefore required to devise the appropriate counter-measures if necessary. The main contributors to the longitudinal impedance model of the new ESRF-EBS storage ring were simulated. A preliminary longitudinal impedance model is presented and preliminary tracking simulations are shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK058
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK066	Calculation of Wakefields and Higher Order Modes for the Vacuum Chamber of the CMS, ATLAS, ALICE and LHCb Experiments for the HL-LHC	wakefield, vacuum, higher-order-mode, dipole	3081
	R. Wanzenberg, O. Zagorodnova DESY, Hamburg, Germany E. Métral, B. Salvant CERN, Geneva, Switzerland
	Funding: Partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The High Luminosity Large Hadron Collider (HL-LHC) project was started with the goal to extend the discovery potential of the Large Hadron Collider (LHC). The HL-LHC study implies also upgraded dimensions of the experimental beam pipes of the CMS, ATLAS, ALICE and LHCb experiments. The trapped monopole and dipole Higher Order Modes (HOMs) and the short range wakefields for the new design of the vacuum chambers were calculated with help of the computer codes MAFIA and ECHO2D. The results of the short range wakefields calculations and the HOMs calculations are presented in this report. The short range wakefields are presented in terms of longitudinal and transverse wake potentials and also in terms of loss and kick parameters. Selected results from the HOMs calculations , including the the frequency, the loss parameter, the R/Q and the Q value are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK066
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK071	Resistive-Wall Impedance Effects for the New KEK Light Source	vacuum, betatron, feedback, storage-ring	3095
	N. Nakamura KEK, Ibaraki, Japan
	KEK Light Source (KEK-LS) is a 3-GeV storage ring of 20-cell HMBA (Hybrid Multi-Bend Achromat) lattice, which is planned to be constructed as a successor of the two existing Photon Factory storage rings (PF ring and PF-AR) in the KEK Tsukuba Campus. In this ring, a lot of in-vacuum undulators with a small magnetic gap (4 mm at minimum) will be installed and the vacuum pipe of a small aperture (25 mm in diameter) will be used. In addition, NEG coating, having a low electric conductivity, will be utilized for the vacuum pipe to ensure a sufficient beam lifetime early in the machine commissioning. In this paper, the heating power due to the longitudinal RW impedance and the growth rate of coupled-bunch instability caused by the transverse RW impedance are calculated and the effects of the RW impedance on KEK-LS are presented. K. Harada et al., Proc. of IPAC2016, Busan, Korea, pp.3251-3253; K. Harada et al., these proceedings.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK071
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK078	Development of the Impedance Model in HEPS	vacuum, kicker, injection, feedback	3110
	N. Wang, Z. Duan, X.Y. Li, H. Shi, S.K. Tian, G. Xu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a new designed photon source at beam energy of 6 GeV. Due to the small beam pipe aperture and a large number of insertion devices in the machine, the impedance can drive collective instabilities and limit the machine performance. Therefore, a thorough estimation of the coupling impedance is necessary in controlling the total impedance of the whole machine. A primary impedance model is obtained for the storage ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK078
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK081	The Logitudinal Broadband Impedance and Energy Spread Measurements at the VEPP-4M Electron-Positron Collider	electron, synchrotron, collider, scattering	3117
	V.M. Borin, V.A. Kiselev, G.Y. Kurkin, S.A. Nikitin, P.A. Piminov, S.V. Sinyatkin BINP SB RAS, Novosibirsk, Russia V.L. Dorokhov, O.I. Meshkov BINP, Novosibirsk, Russia
	The paper presents measurements of the longitudinal broadband impedance and beam energy spread of the beam at the VEPP-4M electron-positron collider in an energy range of 1.0 - 3.5 GeV. In order to measure the longitudinal bunch size at various beam currents we used PS-1/S1 streak camera with picosecond temporal resolution. The dependence of bunch length from the bunch current at different energies demonstrates a microwave instability threshold. The bunch lengthening was caused by potential well distortion as well. Potential well distortion lengthening was used to estimate a value of the reactive part of the longitudinal impedance of the vacuum chamber of the collider Observed microwave instability thresholds was used to measure the value of the broadband impedance. The impact of the Touschek effect in the beam energy spread is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK081
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK087	Measurement and Characterization of Cable Losses for High Voltage Coaxial Cables Used in Kicker Systems	kicker, simulation, network, injection	3131
	A. Ferrero Colomo, L. Ducimetière, T. Kramer, L. Sermeus CERN, Geneva, Switzerland
	In the framework of CERN's LHC Injector Upgrade, simulation models for kicker pulse generators have been improved. A key element in the conventional pulse generators, among many others, are the high voltage coaxial cables. Since they can have significant impact on the waveform characteristics, an accurate cable model for simulation is crucial for reliable results during development. For this purpose, precise measurements of scatter parameters have been carried out in order to improve existing simulation models. Specialized high voltage cables, sometimes SF6 gas filled, used in various CERN kicker systems are usually large, heavy, not very flexible and often only one end is easy accessible. In addition, the impedance of these cables is rarely of 50 Ohms, which presents an extra difficulty. This paper describes the methods that have been defined and used to measure any kind of coaxial structures relying on S11 parameters exclusively. Measurements for various specialized cable types are presented and compared with their improved models. The implications for overall kicker system performance are briefly discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK087
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK089	Characterization of Resonant Impedances of CERN-SPS Gate Valves	simulation, resonance, coupling, 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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK090	Characterization of Shielding for the CERN-SPS Vacuum Flanges With Respect to Beam Coupling Impedance	shielding, vacuum, resonance, coupling	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK090
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK094	LEIR Impedance Model and Coherent Beam Instability Observations	ion, injection, space-charge, electron	3159
	N. Biancacci, H. Bartosik, A. Huschauer, E. Métral, T.L. Rijoff, B. Salvant, R. Scrivens CERN, Geneva, Switzerland M. Migliorati University of Rome La Sapienza, Rome, Italy
	The LEIR machine is the first synchrotron in the ion acceleration chain at CERN and it is responsible to deliver high intensity ion beams to the LHC. Following the recent progress in the understanding of the intensity limitations, detailed studies of the machine impedance started. In this work we describe the present LEIR impedance model, detailing the contribution to the total longitudinal and transverse impedance of several machine element. We then compare the machine tune shift versus intensity predictions against measurements at injection energy and summarize the coherent instability observations in absence of transverse damper feedback.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK094
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK095	Evaluation of Longitudinal Beam Impedance in the Beam Gas Ionization Monitor of the CERN-PS Accelerator	coupling, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK095
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK096	Assessment of Beam Impedance for the CERN-PS Booster Wire Scanner	simulation, coupling, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK096
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK100	The Applicability of NEG Coated Undulator Vessels for the CLARA FEL Test Facility	vacuum, FEL, wakefield, undulator	3181
	O.B. Malyshev, K.B. Marinov, K.J. Middleman, N. Thompson, R. Valizadeh, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom O.B. Malyshev, K.J. Middleman, N. Thompson, R. Valizadeh, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom
	CLARA is a FEL test facility at Daresbury Laboratory (DL), UK. The undulator vacuum chamber is 20 m long with inner diameter 6 mm and its vacuum performance can benefit from a NEG coating. The thickness of the coating layer must be carefully optimised. A layer ~ 1 um would help the vacuum but a thinner layer would be partially transparent for the EM field reducing the resistive wall wakefields due to the NEG. A very thin layer, however, may not yield the necessary vacuum performance. Two types of NEG coatings produced at DL - dense and columnar - were considered. Their bulk conductivities were measured in a separate study. The resistive wall wakefield impedance was calculated following the standard approach for multilayer vessels. A 250 fs rms electron bunch was generated in ASTRA and its wakefield was obtained from the vessel impedance. The FEL performance was then studied through GENESIS simulations and the result compared to the case with no wakefields. It was found that NEG layers thicker than 100 nm give an unacceptable reduction of the FEL power and the vacuum performance of such thin coatings is unknown. Possible solutions to this problem are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK100
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK106	Impedance and Collective Effects for the Advanced Light Source Upgrade at LBNL	simulation, wakefield, cavity, vacuum	3192
	S. Persichelli, J.M. Byrd, S. De Santis, D. Li, T.H. Luo, C. Steier, M. Venturini LBNL, Berkeley, California, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 The upgrade of the Advanced Light Source (ALS-U) consists of a multiband achromat ultralow emittance lattice for the production of diffraction-limited soft x-rays. A very important issue for ALS-U is represented by instabilities induced by wakefields, that may limit the peak current of individual bunches and the total beam current. In addition, vacuum chamber apertures of few millimeters, that are a key feature of low-emittance machines, can result in a significant increase in the Resistive Wall (RW) impedance. In this paper we present progress on establishing short range wakefield model for ALS-U and evaluating the impact on the longitudinal and transverse single-bunch dynamics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK106
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK113	Entrance and Exit CSR Impedance for Non-Ultrarelativistic Beam	wakefield, dipole, bunching, FEL	3214
	R. Li JLab, Newport News, Virginia, USA C.-Y. Tsai Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
	Funding: Work supported by the Department of Energy, Laboratory Directed Research and Development Funding, under Contract No. DE-AC05-06OR23177 For a high-brightness electron beam being transported through beamlines involving bending systems, the coherent synchrotron radiation (CSR) and longitudinal space charge (LSC) interaction could often cause microbunching instability. The semi-analytical Vlasov solver for microbunching gain* depends on the impedances for the relevant collective effects. The existing results for CSR impedances are usually obtained for the ultrarelativistic limit. To extend the microbunching analysis to cases of low energies, such as the case of an ERL merger, or to density modulations at extremely small wavelength, it is necessary to extend the impedance analysis to the non-ultrarelativistic regime. In this study, we present the impedance analysis for the transient CSR interaction in the non-ultrarelativistic regime, for transients including both entrance to and exit from a magnetic dipole. These impedance results will be compared to their ultra-relativistic counterparts, and the corresponding wakefield obtained from the impedance for low-energy beams will be compared with the existing results of transient CSR wakefield for general beam energies. C.-Y. Tsai et al., Proc. of IPAC'15, 596 (2015). C. Mitchell et al ., Proc. of IPAC'13, 1832 (2014). * E. L. Saldin et al ., Nucl. Instrum. Meth. A 398, 373 (1997).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK113
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA022	RECENT TWO-BEAM ACCELERATION ACTIVITIES AT ARGONNE WAKEFIELD ACCELERATOR FACILITY	acceleration, experiment, accelerating-gradient, wakefield	3305
	J.H. Shao, S.P. Antipov, M.E. Conde, W. Gai, Q. Gao, G. Ha, W. Liu, N.R. Neveu, J.G. Power, Y.R. Wang, E.E. Wisniewski, L.M. Zheng ANL, Argonne, Illinois, USA C.-J. Jing, J.Q. Qiu Euclid TechLabs, LLC, Solon, Ohio, USA J. Shi, D. Wang TUB, Beijing, People's Republic of China
	The Two-Beam Acceleration (TBA) is a modified approach to the structure-based wakefield acceleration which may meet the luminosity, efficiency, and cost requirement of a future linear collider. Recently, various TBA experiments have been carried out at the Argonne Wakefield Accelerator Facility (AWA). With X-band metallic power extractors and accelerators, a 70 MeV/m average accelerating gradient has been demonstrated in two stages while a 150 MeV/m gradient as well as 300 MW extracted power have been achieved in a single stage. In addition, low cost K-band dielectric power extractor and accelerator have also been developed. The preliminary results show power extraction of 55 MW and an average accelerating gradient of 28 MeV/m.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA022
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA024	Design of an Inductive Adder for the FCC Injection Kicker Pulse Generator	kicker, injection, high-voltage, collider	3312
	D. Woog, M.J. Barnes, L. Ducimetière, J. Holma, T. Kramer CERN, Geneva, Switzerland
	The injection system for a 100 TeV centre-of-mass collider is an important part of the Future Circular Collider (FCC) study. Due to issues with conventional kicker systems, such as self-triggering and long term availability of thyratrons and limitations of HV-cables, innovative design changes are planned for the FCC injection kicker pulse generator. An inductive adder (IA) based on semiconductor (SC) switches is a promising technology for kicker systems. Its modular design, and the possibility of an active ripple suppression are significant advantages. Since the IA is a complex device, with multiple components whose characteristics are important, a detailed design study and construction of a prototype is necessary. This paper summarizes the system requirements and constraints, and describes the main components and design challenges of the prototype IA. It outlines the results from simulations and measurements on different magnetic core materials as well as on SC switches. The paper concludes on the design choices and progress for the prototype to be built at CERN.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA024
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA036	The LHC Injectors Upgrade (LIU) Project at CERN: Proton Injector Chain	linac, cavity, injection, proton	3335
	K. Hanke, J. Coupard, H. Damerau, A. Funken, B. Goddard, A.M. Lombardi, D. Manglunki, S. Mataguez, M. Meddahi, B. Mikulec, G. Rumolo, R. Scrivens, E.N. Shaposhnikova, M. Vretenar CERN, Geneva, Switzerland
	The LHC Injectors Upgrade (LIU) project at CERN aims at delivering high brightness beams required by the LHC in the high-luminosity LHC (HLLHC) era. The project comprises a new H⁻ Linac (Linac4) as well as a massive upgrade of the PS Booster, PS and SPS synchrotrons. This paper gives an update of the activities regarding the proton injector chain. We present the target beam parameters, a brief status of the upgrade work per machine and the outcome of the recent reviews. The planning for the implementation of the hardware upgrades and the re-commissioning of the complex will also be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA036
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA047	Input Signal Generation for Barrier Bucket RF Systems at GSI	cavity, synchrotron, storage-ring, operation	3359
	J. Harzheim, D. Domont-Yankulova, K. Groß, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany M. Frey, H. Klingbeil GSI, Darmstadt, Germany
	At the GSI facility in Darmstadt, Germany, Barrier Bucket RF systems are currently designed for the SIS 100 synchrotron (part of the future FAIR facility) and the Experimental Storage Ring (ESR). The purpose of these systems is to provide single sine voltage pulses at the cavity gap. Due to the high requirements regarding the gap signal quality, the calculation of the pre-distorted input signal plays a major role in the system development. A procedure to generate the input signal based on the dynamic properties in the linear region of the system has been developed and tested at a prototype system. It was shown that this method is able to generate single sine gap signals of high quality in a wide voltage range. As linearity can only be assumed up to a certain magnitude, nonlinear effects limit the quality of the output signal at very high input levels. An approach to overcome this limit is to extend the input signal calculation to a nonlinear model of the system. In this contribution, the current method to calculate the required input signal is presented and experimental results at a prototype system are shown. Additionally, first results in the nonlinear region are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA047
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA060	Construction of the New Kicker Magnet Systems for PF-Advanced Ring	kicker, injection, timing, power-supply	3401
	A. Ueda, S. Asaoka, T. Honda, S. Nagahashi, N. Nakamura, T. Nogami, H. Takaki, T. Uchiyama KEK, Ibaraki, Japan
	From July 2016 we are constructing a new beam transport (BT) line for the Photon Factory Advanced Ring (PF-AR). The new BT line was designed to transport the full energy 6.5-GeV beam directly from the LINAC, and the top up injection will be possible for the PF-AR. We designed and produced new kicker systems for this project. Three kicker magnets are used for the injection of the 6.5-GeV beam. The kicker magnets were designed as a window frame type ferrite core magnet. The magnetic fields of these magnets have been measured by the search coil method. We paid attention to evaluating eddy current losses of the metal coated ceramic duct in the magnetic field measurement.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA060
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA094	Study of an Improved Beam Screen Design for the LHC Injection Kicker Magnet for HL-LHC	kicker, injection, simulation, coupling	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
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA094
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA095	Preliminary Estimate of Beam Induced Power Deposition in a FCC-hh Injection Kicker Magnet	kicker, injection, coupling, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA095
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA097	Upgrading the SPS Fast Extraction Kicker Systems for HL-LHC	kicker, electron, extraction, resonance	3483
	M.J. Barnes, M.S. Beck, H.A. Day, L. Ducimetière, E. Garcia-Tabares Valdivieso, B. Goddard, H. Neupert, A. Romano, L. Vega Cid, W.J.M. Weterings CERN, Geneva, Switzerland C. Zannini ADAM SA, Geneva, Switzerland
	The CERN SPS has two fast extraction systems, each consisting of travelling wave kicker magnets (MKEs). The beam induced heating in the ferrite yoke of these magnets was historically kept to an acceptable level by implementing water cooling of the kicker magnets: in addition serigraphy was applied on the surfaces of the ferrite yoke facing the beam. Nevertheless, high intensity beams needed in the future for HL-LHC will significantly increase the beam induced heating, potentially raising the MKE ferrite yoke temperature to its Curie point. Hence detailed studies of longitudinal beam coupling impedance were carried out to identify simple but effective methods of further reducing beam induced power deposition. Based on the results of these studies, and in the framework of the LHC Injectors Upgrade (LIU) project, an upgraded MKE kicker magnet was installed during the 2015-2016 shutdown. This paper reports and compares results of predictions, laboratory measurements, temperature measurements during SPS operation, and machine development studies. Measurements of both dynamic pressure rise in the upgraded magnet and Secondary Electron Yield, on samples, are also reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA097
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA099	Influence of Conducting Serigraphy Upon Field Pulse Shape of the SPS Extraction Kicker Systems	kicker, flattop, extraction, high-voltage	3491
	A. Adraktas, M.J. Barnes, L. Ducimetière CERN, Geneva, Switzerland
	Fast pulsed magnets with ferrite yokes are used for beam extraction from the CERN SPS accelerator. These kickers are transmission line type magnets with a rectangular shaped aperture through which the beam circulates. Unless special precautions are taken, the beam impedance of the yoke can provoke significant induced heating, especially for high intensity beams. Previous upgrades of the SPS extraction kicker magnets have included silver fingers serigraphed on the surface of the ferrite facing the beam, to help shield the ferrite yoke from circulating beam. Beam based measurements of the extracted beam indicated that the serigraphy may influence the shape of the field pulse, causing it to increase slightly in magnitude during the flat-top. Hence theoretical studies have been carried out to determine whether the serigraphy influences the field pulse: these studies are reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA099
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA100	Operational Experience of the Upgraded LHC Injection Kicker Magnets During Run 2 and Future Plans	injection, kicker, electron, vacuum	3495
	M.J. Barnes, A. Adraktas, G. Bregliozzi, L. Ducimetière, B. Goddard, B. Salvant, J. Sestak, L. Vega Cid, W.J.M. Weterings, C. Yin Vallgren CERN, Geneva, Switzerland
	During Run 1 of the LHC, one of the injection kicker magnets caused occasional operational delays due to beam induced heating with high bunch intensity and short bunch lengths. In addition, there were also sporadic issues with vacuum activity and electrical flashover of the injection kickers. An extensive program of studies was launched and significant upgrades were carried out during Long Shutdown 1 (LS 1). These upgrades included a new design of beam screen to reduce both beam coupling impedance of the kicker magnet and the electric field associated with the screen conductors, hence decreasing the probability of electrical breakdown in this region. This paper presents operational experience of the injection kicker magnets during the first years of Run 2 of the LHC, including a discussion of faults and kicker magnet issues that limited LHC operation. In addition, in light of these issues, plans for further upgrades are briefly discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA100
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA101	Review of Stripline Beam Impedance: Application to the Extraction Kicker for the CLIC Damping Rings	coupling, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA101
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA108	Operational Feedback and Analysis of Current and Future Designs of the Injection Protection Absorbers in the Large Hadron Collider at CERN	injection, vacuum, operation, alignment	3517
	D. Carbajo Perez, N. Biancacci, C. Bracco, G. Bregliozzi, M. Calviani, M.I. Frankl, L. Gentini, S.S. Gilardoni, G. Iadarola, I. Lamas Garcia, A. Lechner, A. Perillo-Marcone, B. Salvant CERN, Geneva, Switzerland
	Two injection protection absorbers, so-called TDIs (Target Dump Injection), are installed close to Interaction Points IP2 and IP8 of the Large Hadron Collider (LHC) right downstream of the injection kicker magnets (MKI). Malfunction or timing errors in the latter lead to wrong steering of the beam, which must then be intercepted by the TDI to avoid downstream equipment (which includes superconducting magnets) damage. In recent years, MKI failures during operation have brought to light opportunities for improvement of the TDI. The upgrade of this absorber, so-called TDIS (where S stands for segmented), is conceived as part of the High Luminosity-LHC (HL-LHC) project and those operational issues are taken into account for its design. The present document describes not only the aspects related to the current TDI performance and their impact in its successor's design but also the key modifications to cope with the stronger requirements associated to the higher luminosity goal.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA108
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA121	Thermal Experimet Results on TPS Beam Position Monitors	simulation, cavity, storage-ring, vacuum	3554
	Y.T. Huang, C.K. Chan, J. -Y. Chuang, I.C. Sheng, Y.C. Yang NSRRC, Hsinchu, Taiwan
	Beam position monitors mounted in straight sections exhibit an unusual temperature rise which is attributed to poor thermal and electrical conductivity of the stainless steel BPM chamber, to the vicinity to RF-bellows, and the large button electrode size to get superior signal levels. Thermocouples tied to BPM flanges and RF bellows show that the temperature could reach 50 oC when storing a beam current of 400 mA and BPMs located between two RF-bellows in RF cavity sections responds by even 5-10 oC higher values than average. To resolve this issue, off site experiments and simulations were conducted to further understand the heat flow in the whole structure. In this paper we discuss more details of these studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA121
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA129	Arc-Flash Hazard and Protection for Electric Switchboard at NSRRC	detector, site, photon, power-supply	3571
	T.-S. Ueng, Y.F. Chiu, C.K. Kuan, K.C. Kuo, Y.-C. Lin NSRRC, Hsinchu, Taiwan
	During the operation of electrical equipment the arc-flash accident could damage the equipment and endanger the working personnel. In order to prevent this type of accidents from happening and to minimize the damages, a delicate setup is being installed inside the electric switchboard for suppressing the accidents at the initial stage of arcing at NSRRC's power system. The installed device includes the arc sensor, the smoke detector, the high rupturing capacity fuse, the circuit breaker and the protection relay. Further improvement on preventing the arc-flash accidents is also under study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA129
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA131	Single-Inductor Bipolar Outputs Power Converters	power-supply, controls, electronics, operation	3577
	Y.T. Li, C.Y. Liu, K.-B. Liu, B.S. Wang, Y.S. Wong NSRRC, Hsinchu, Taiwan
	In the circuit design for electronic products, bipolar power supply is often required. A non-isolated dual polarity power supply design is using two inductors to achieve this function. The number of inductors on the circuit would increase both the cost of products and space requirement. So the use of a single inductor bipolar power converter design can effectively reduce the cost and space to enhance product competitiveness. In this paper, the principle of a new single-inductor bipolar power converter will be described and tested to prove the feasibility of this design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA131
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA134	Impedance Measurement of Vacuum Chamber Components for the Advance Photon Source (APS) Upgrade	simulation, cavity, vacuum, photon	3583
	M.P. Sangroula IIT, Chicago, Illinois, USA R.M. Lill, R.R. Lindberg, X. Sun ANL, Argonne, Illinois, USA
	Funding: U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC0206CH11357. The proposed Advance Photon Source Upgrade (APS-U) employs a multi-bend achromat (MBA) lattice to increase the photon brightness by two to three orders of magnitude. One of the main design challenges of the upgrade is to minimize rf heating and collective instabilities associated with the impedance of small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. Here, we present the summary of the impedance contributions for the APS-U and describe our planned impedance measurement technique, including some measurement results for the non-evaporative getter (NEG)-coated copper chamber and simulation results for other critical components using a novel Goubau line (G-line) set up.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA134
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA141	Ion Cyclotron Resonance Heating Transmitter Opening Switch Upgrade	operation, plasma, high-voltage, resonance	3600
	M.P.J. Gaudreau, M.K. Kempkes, J. Kinross-Wright, R.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Diversified Technologies Inc. (DTI) has installed a high-power solid-state opening switch upgrade package to replace the mercury ignitron crowbars in the Ion Cyclotron Resonance Heating (ICRH) Transmitters at MIT Plasma Fusion Science Center's (PFSC) Alcator C Mod, a Tokamak-type fusion experimental device. The speed of the series opening switch avoids the large fault currents on the transformer and power feed inherent with a crowbar. This improvement enables re-optimization of the Transformer/Rectifier (T/R) set, ultimately allowing increased power output and increased tetrode reliability. The ratings of the prior high voltage power supply are a compromise between high output power (lower impedance required from the T/R set) and crowbar reliability (higher impedance required from the power supply to limit fault current). DTI's opening switch upgrade safely allows the use of significantly reduced transformer impedance and lower droop, giving increased power as well as improved tube protection. DTI's opening switch kit can readily be adapted to any similar transmitters as an upgrade from a crowbar.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA141
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB002	Update of the Collective Effects Studies for Sirius	simulation, radiation, undulator, operation	3680
	F.H. de Sá, H.O.C. Duarte, L. Liu LNLS, Campinas, Brazil
	An updated impedance budget for Sirius, with contributions from 3D electromagnetic simulations and analytic calculations, is presented and the estimates for single and multi-bunch instability thresholds for the first operation phase are re-evaluated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB002
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB003	Harmonic RF System for the ESRF EBS	cavity, simulation, beam-loading, synchrotron	3684
	N. Carmignani, J. Jacob, B. Nash, S.M. White ESRF, Grenoble, France
	A harmonic RF system for bunch lengthening to increase the Touschek lifetime of the ESRF Extemely Brilliant Source (EBS) is under study. Multiparticle simulations have been performed to study the bunch lengthening and the bunch shape with impedance effect and with third or fourth harmonic cavities. The effect of a harmonic RF system on the microwave instability is studied, finding an increase in the threshold. The AC Robinson instability threshold with a superconducting harmonic cavity has been studied with multiparticle simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB003
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB005	Improvement of the Analytic Vlasov Solver DELPHI	simulation, synchrotron, proton, hadron	3688
	D. Amorim Université Grenoble Alpes, Grenoble, France N. Biancacci, K.S.B. Li, E. Métral CERN, Geneva, Switzerland
	The simulation code DELPHI is an analytic Vlasov solver which allows to evaluate the beam transverse stability with respect to impedance effects. It allows to perform fast scans over parameters such as chromaticity, damper gain or beam intensity for a given impedance model and particle distribution. In order to improve the simulation code, new longitudinal particle distributions have been implemented. The simulations results obtained with these distributions are compared to theoretical predictions. An additional post-processing of DELPHI's output has also been implemented, allowing to reconstruct the signal seen by head-tail stripline monitors, in particular in presence of bunch-by-bunch damper. The results are compared to theoretical models, to pyHEADTAIL simulations and to measurements performed in the LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB005
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB020	Coupling Impedances and Collective Effects for FCC-ee	vacuum, collective-effects, coupling, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB025	Simulation Studies of Transverse Beam Instabilities and Measures Beyond 1 MW Beam Power in the 3-GeV RCS of J-PARC	simulation, injection, acceleration, extraction	3750
	P.K. Saha, H. Hotchi, Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The transverse impedance of the extraction kicker magnets is a significant beam instability source in the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex). The systematic simulation studies for beam instability by including the space charge effect has been done by using the ORBIT code. The simulation results are well reproduced in the corresponding measurements. The designed 1 MW beam power has recently been accomplished by keeping sextuple magnets off in order to stabilize the beam by utilizing the large lattice chromaticity throughout the entire acceleration period. The RCS simultaneously delivers extracted beam to the MLF (Material and Life Science Experimental Facility) and the MR (Main Ring). In order to ensure 1 MW beam power at the MLF even when RCS beam sharing to the MR is twice increased as well as when a second target station is constructed at the MLF, a beam power of 1.5 MW has to be realized in the RCS. However, the simulation shows that beyond 1 MW the beam is unstable even if no chromaticity is corrected. A reduction of the kicker impedance by at least a half is required in order to achieve 1.5 MW beam power in the RCS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB025
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB029	Simulation of the Single Bunch Instabilities for the High Energy Photon Source	injection, simulation, operation, photon	3760
	Z. Duan, N. Wang, H.S. Xu IHEP, Beijing, People's Republic of China
	Funding: Work supported by Natural Science Foundation of China (No.11605212). Timing modes pursing a large single bunch charge will be important operation modes for the green-field High Energy Photon Source (HEPS). The single bunch instabilities are simulated with the elegant tracking code, based on the current impedance budget. In particular, a novel on-axis accumulation scheme* based on the RF gymnastics of an active double-RF system was proposed as a candidate injection scheme for HEPS, while the zero-current rms bunch length dramatically decreases during the injection, from 32 mm to 3 mm, over a time duration of about 200 ms. The single bunch instabilities are evaluated for both the operation mode with optimal bunch lengthening as well as the injection mode with the very short bunch length, as a first step in understanding the possible beam instability for this injection scheme. * G. Xu, et al., in Proc. IPAC'16, pp. 2886-2888. Z. Duan, et al., in Proc. eeFACT 2016.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB029
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB030	Studies on Collective Instabilities in HEPS	injection, operation, ion, damping	3763
	N. Wang, Z. Duan, C. Li, S.K. Tian, H.S. Xu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a new designed photon source at beam energy of 6 GeV. Due to the small beam size and increased coupling impedance with the restricted beam pipe aperture, the collective effects may bring new challenges to the physical design of the machine. The collective instabilities are estimated for different operation mode. The critical instability issues are also identified for each mode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB030
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB032	Estimates of Collective Effects in the HALS Storage Ring Having the First Version Lattice	emittance, coupling, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB032
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB057	Method to Calculate the Longitudinal Impedance From a Partial Wakefield Simulation	wakefield, simulation, cavity, factory	3844
	N.C. Shipman UMAN, Manchester, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom R. Calaga CERN, Geneva, Switzerland J.A. Mitchell Lancaster University, Lancaster, United Kingdom
	When simulating modes with high Q-factors, the wakefield length necessary to calculate the impedance spectrum can often mean a computation time of several weeks or more. A method has been developed which enables the longitudinal impedance and Q-factors of multiple modes to be calculated from a partially decayed wakefield simulation. This paper presents an overview of the method along with preliminary, proof of principle, results showing that considerable simulation time can be saved whilst maintaining a good degree of accuracy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB057
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB065	A Tool for Small Longitudinal Beam Dynamics in Synchrotrons	synchrotron, simulation, emittance, longitudinal-dynamics	3865
	J.-F. Ostiguy, V.A. Lebedev Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy A number of codes are available to simulate longitudinal dynamics in synchrotrons. The most established ones include TIBETAN, LONG1D, ORBIT, and ESME. While they embody a wealth of accumulated wisdom and experience, most of these codes were written decades ago and to some extent they reflect the constraints of their time. As a result, there is interest for updated tools taking better advantage of modern software and hardware capabilities. At Fermilab, the PIP-II project has provided the impetus for development of such a tool. In this contribution, we discuss design decisions and code architecture. A selection of test cases based on an initial prototype are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB065
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB080	Estimations of Coherent Instabilities for JLEIC	electron, ion, proton, collider	3903
	R. Li JLab, Newport News, Virginia, USA
	Funding: Work supported by the Department of Energy, Laboratory Directed Research and Development Funding, under Contract No. DE-AC05-06OR23177 JLEIC is the medium energy electron-ion collider currently under active design at Jefferson Lab. The design goals of JLEIC are both high luminosity (1033-1034 cm^-2ses⁻¹) and high polarization (>70%) for the electron and light ion beams, for a wide range of electron and ion beam energies and for a wide spectrum of ion species. The unprecedented luminosity goal for this electron-ion collider sets strong requirements for the understanding and management of potential collective effects in JLEIC. In this paper, we present preliminary estimations of single and coupled bunch coherent instabilities for the electron and proton beams at collision energies for the JLEIC design. Further improvement of the estimations and mitigation methods are discussed. MEIC design summary, http://arxiv.org/ftp/arxiv/papers/1504/1504.07961.pdf, (2015).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB080
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB111	Sub-Femtosecond Jitter Ultra High Performance Oscillators for Accelerator Timing	controls, coupling, cavity, electron	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB111
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB115	Development of a Longitudinal Feedback System for Coupled Bunch Instabilities Caused by the Accelerating Mode at Superkekb	cavity, operation, damping, target	3989
	K. Hirosawa, K. Akai, E. Ezura, T. Kobayashi, K. Nakanishi, M. Nishiwaki, S.I. Yoshimoto KEK, Ibaraki, Japan
	SuperKEKB is an asymmetric energy electron-positron circular collider. Phase-I commissioning was operated from February to June in 2016. The purpose of this accelerator is to aim at the higher luminosity than KEKB, so a larger beam current is made for it. In the future plan, beam currents in the electron and positron rings will be increased to 2.6A and 3.6A, respectively. As we consider beam dynamics in the storage ring, higher mode instability associated with the accelerating mode will be caused by a large beam current. Especially the target instability of this study is called μ=-2 mode Coupled Bunch Instability. To suppress it, we developed new feedback components for longitudinal coupled bunch instability. We have same mechanism feedback components for KEKB, but it supports only μ=-1 mode instability. Since a large current makes μ=-1 mode instability big, there is a possibility that suppression is difficult only by using KEKB components. In order to deal with this problem, new components we developed support μ=-1, -2, and -3 mode instabilities, and we improved the performance and usability as compared to existing components. We schedule studies using a beam at Phase-II.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB115
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK002	Development of a Range of High Peak Power Solid-State Amplifiers for Use in the Heavy Ion Linac at JINR, Dubna	cavity, ion, linac, heavy-ion	4108
	S.C. Dillon, J.L. Reid Tomco Technologies, Stepney, South Australia, Australia A.V. Butenko JINR, Dubna, Moscow Region, Russia H. Höltermann, H. Podlech, U. Ratzinger BEVATECH, Frankfurt, Germany
	A range of LDMOS based amplifiers rated for up to 340kW peak power and operating at 100.625MHz were developed for use as RF sources for driving cavities in the heavy ion LINAC (HILac) at JINR, Dubna. The final solution had to be compact and competitive while addressing technical challenges such as phase and amplitude stability, long term reliability, reflected power handling and serviceability. Design considerations and performance results are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK002
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK014	Travelling Wave Accelerating Structure for Areal 50 MeV Energy Upgrade	cavity, simulation, electron, gun	4130
	A. Vardanyan, V. Danielyan, S.G. Dekhtiarov, B. Grigoryan, L. Hakobyan, T. Markosyan, A.S. Simonyan CANDLE SRI, Yerevan, Armenia W. Ackermann TEMF, TU Darmstadt, Darmstadt, Germany A.V. Tsakanian HZB, Berlin, Germany
	AREAL facility development implies energy upgrade to 50 MeV in order to drive a THz free electron laser. To reach this goal, the installation of two 1.6 m long S-Band travelling wave accelerating sections, with nominal accel-erating gradient of 15 MV/m, are foreseen. In this paper the design study of accelerating sections along with the matching performance of RF couplers are presented. The simulations are performed using the CST Microwave Studio. The first results of the accelerating structure proto-type fabrication are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK014
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK015	Prototype Results of the ESR Barrier-Bucket System	cavity, accumulation, coupling, 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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK043	Design and Optimization of a 2MeV X-Band Side Coupled Accelerating Structure	coupling, 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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK045	Design of a C-band Travelling-wave Accelerating Structure at IHEP	cavity, linac, simulation, wakefield	4196

Paper

Title

Other Keywords

Page

Design and Prototyping of New CERN Collimators in the Framework of the LHC Injector Upgrade (LIU) Project and the High-Luminosity (HL-LHC) Project

collimation, dipole, proton, vacuum

80

F.-X. Nuiry, O. Aberle, M. Bergeret, A. Bertarelli, N. Biancacci, R. Bruce, M. Calviani, F. Carra, A. Dallocchio, L. Gentini, S.S. Gilardoni, R. Illan Fiastre, I. Lamas Garcia, A. Masi, A. Perillo-Marcone, S. Pianese, S. Redaelli, E. Rigutto, B. Salvant
CERN, Geneva, Switzerland

In the framework of the Large Hadron Collider (LHC) Injectors Upgrade (LIU) and the High-Luminosity LHC (HL-LHC) Projects at CERN (European Organization for Nuclear Research, in Geneva, Switzerland), collimators in the Super Proton Synchrotron (SPS) to LHC transfer lines as well as ring collimators in the LHC will undergo important upgrades in the forthcoming years, mainly focused during the Long Shutdown 2 foreseen during 2019-2020. This contribution will detail the current design of the TCDIL collimators with a particular emphasis on the engineering developments performed on the collimator jaws, aiming at getting a stringent flatness while consid-ering also the integration of thermal shock resistant materials. The prototyping phase done at CERN will be also described. The activities ongoing to prepare the series production for other LHC collimator types (TCPPM, TCSPM, TCTPM, TCLD) will be presented, describing the role that each of these collimators play on the HL-LHC Project. A focus on the series production processes, the manufacturing and assembly technologies involved and the quality and performance assurance tests will be given.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB022

Fabrication Studies of a 650 MHz Superconducting RF Deflecting Mode Cavity for the ARIEL Electron Linac

cavity, niobium, electron, linac

120

D.W. Storey, R.E. Laxdal, B. Matheson, N. Muller
TRIUMF, Vancouver, Canada
D.W. Storey
Victoria University, Victoria, B.C., Canada

A 650 MHz RF deflecting mode cavity is required for the ARIEL electron Linac to separate interleaved beams bound for either rare isotope production or a recirculation loop containing a Free Electron Laser. An RF separator will allow both modes to run simultaneously by imparting opposite transverse deflection to adjacent bunches at 1.3 GHz. The SRF cavity has been designed to provide up to 0.6 MV transverse voltage for operation with up to a 50 MeV CW electron beam. The design was optimised for compact geometry with high shunt impedance. Due to the low dissipated power, the cavity will operate at 4 K and allows for investigations into low cost fabrication techniques. The cavity is being machined from bulk reactor grade ingot Niobium and welds will be performed using TIG welding in an ultra-pure Argon chamber. Results of fabrication studies will be presented as well as measurements performed on a copper prototype cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB052

A Transverse Deflection Structure with Dielectric-Lined Waveguides in the Sub-THz Regime

electron, simulation, emittance, laser

215

F. Lemery
University of Hamburg, Hamburg, Germany
R.W. Aßmann, K. Flöttmann, T. Vinatier
DESY, Hamburg, Germany

Longitudinal bunch measurements are typically done with rf-powered transverse deflection structures with operating frequencies 1-12~GHz. We explore the use of mm-scale, THz-driven, dielectric-lined cylindrical waveguides as transverse deflectors by driving the fundamental deflecting mode of the structure, the HEM₁₁. We give a brief overview of the physics, history, and provide an example with a 5~MeV beam using {\sc astra} and {\sc CST-MWS}.
This work was supported by the European Research Council (ERC) under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant agreement no. 609920

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB052

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB071

A Beam Position Monitor for the Diagnostic Line in MEBT2 of J-PARC Linac

diagnostics, linac, pick-up, operation

281

A. Miura, Y. Kawane, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
T. Miyao
KEK, Ibaraki, Japan

In the linac of the Japan Proton Accelerator Research Complex (J-PARC), the neutral hydrogen (H⁰) generation from the negative hydrogen ion (H⁻) beam is one of key issues to mitigate the beam loss. In order to diagnose the H⁰ particles, we installed the bump magnets to make a chicane orbit of the H⁻ beam. To evaluate the horizontal shifts of the beam orbit, a beam position monitor (BPM) is fabricated. The BPM measures the shift-positions with various driving currents of the bump magnets. We employed the WSM to measure the H⁻ beam profile. It also help us to compare the shift-positions measured by BPM. In this paper, the design and the performance of the BPM is described. In addition, we describe how to compare the shift position.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB071

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB113

Usage of the Transverse Damper Observation Box for High Sampling Rate Transverse Position Data in the LHC

injection, diagnostics, pick-up, operation

389

L.R. Carver, X. Buffat, A.C. Butterworth, W. Höfle, G. Iadarola, G. Kotzian, K.S.B. Li, E. Métral, M. Ojeda Sandonís, M.E. Söderén, D. Valuch
CERN, Geneva, Switzerland

The transverse damper observation box (ADTObsBox) is a device that makes accessible the bunch-by-bunch turn-by-turn data recorded from the pickups of the LHC transverse damper. This device can provide online transient analysis of different beam dynamics effects (tunes and damping times at injection, for example), while also under development is an online coherent instability triggering system. This paper will provide an overview of the current setup and plans for future upgrades, as well as detailing how it deals with the large volume of data being generated. The results of some analysis that rely on the ADTObsBox will also be shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB113

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPAB152

Precise Synchronous Phase Measurements

storage-ring, synchrotron, synchrotron-radiation, radiation

487

W.X. Cheng, B. Bacha, K. Ha, O. Singh
BNL, Upton, Long Island, New York, USA

Funding: DOE contract No: DE-SC0012704
Precise measurements of storage ring synchronous phase helps to understand the machine impedance and improve the high current performance. We present different methods tested at NSLS-II, including the streak camera measurement, relative phase measurement from a high sampling frequency oscilloscope by comparing the beam signal and reference signal. Both streak camera and scope method have high precision to measure the synchronous phase (<1ps). Other methods to measure the synchronous phase include the I-Q detection from BPM electronics, FPM scope have been tested as well. We have used these systems to study the synchronous phase shift at different beam current, RF voltages and ID gaps. Recent results will be presented and discussed in the paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB152

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPIK013

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

gun, electron, cavity, coupling

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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPIK043

Beam-Based Waveform Measurements of the CERN PS Injection Kicker

kicker, flattop, injection, timing

603

V. Forte, W. Bartmann, J.C.C.M. Borburgh, L.M.C. Feliciano, A. Ferrero Colomo, M.A. Fraser, T. Kramer, L. Sermeus
CERN, Geneva, Switzerland

In the framework of the LHC Injectors Upgrade (LIU) project, a beam-based technique has been developed for measuring the waveform the CERN Proton Synchrotron (PS) horizontal injection kicker, named KFA45. The technique avoids the need for tedious magnetic measurements, especially when a spare magnet is presently unavailable and measuring the operational magnet with a magnetic field probe is complicated by integration reasons. In this paper, the technique and results of the waveform measurements are summarised. The results already provide additional information in terms of waveform characterisation for the validation of numerical simulations and are of great interest for the future LIU performance upgrade.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK043

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPVA034

A Compact EUV Light Source Using a mm-Wave Undulator

undulator, electron, gun, quadrupole

928

F. Toufexis, V.A. Dolgashev, C. Limborg-Deprey, 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.
We are building an Extreme Ultra Violet (EUV) light source based on a 1.75 mm period RF undulator*. We will use a thermionic X-Band injector which utilizes RF bunch compression. The beam is accelerated using an X-Band traveling wave accelerating structure followed by a high shunt impedance standing wave accelerating structure up to 129 MeV. The beam then goes through a 91.392 GHz RF undulator with a period of 1.75 mm, producing EUV radiation around 13.5 nm. The RF undulator is powered by a 91.392 GHz decelerating structure, which extracts the RF power from the spent electron beam. The length of the entire beam line from the cathode to the beam dump is approximately 6 m. We describe the design and projected operating parameters for this EUV light source.
* 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-MOPVA034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPVA080

HOM Simulations and Damping Scheme for CEPC Cavities

HOM, cavity, damping, collider

1052

H.J. Zheng, J. Gao, F. Meng, P. Sha, J.Y. Zhai
IHEP, Beijing, People's Republic of China

In this paper, it will be presented that the higher order mode (HOM) analysis of the 650 MHz cavities for the Circular Electron-Positron Collider (CEPC). The higher order modes excited by the intense beam bunches must be damped to avoid additional cryogenic loss and multi-bunch instabilities. To keep the beam stable, the impedance budget and the HOM damping requirement are given. The conventional coaxial HOM coupler, which will be mounted on the beam pipe, is planned to extract the HOM power below the cut-off frequency of the beam pipe, and the propagating modes will be absorbed by the two HOM absorbers at room temperature outside the cryomodule.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA080

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPVA141

Input RF Coupler Design for Energy Compensator Cavity in eRHIC

cavity, simulation, radiation, synchrotron

1184

C. Xu, S. Bellavia, I. Ben-Zvi, M. Blaskiewicz, Y. Hao, K.S. Smith, R. Than, A. Zaltsman
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
This report gives a detail design of a 1.3 GHz input coupler for second harmonic cavity for eRHIC project. This coupler is designed to transmit 200KW CW RF to the cavity to compensate the synchrotron radiation loss. This report include RF and thermal simulation for this design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA141

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB012

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

coupling, linac, simulation, 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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB070

S-Band Accelerating Structure for High-Gradient Upgrade of TTX

electron, simulation, accelerating-gradient, linac

1485

D.Z. Cao, H.B. Chen, Y.-C. Du, W. Gai, W.-H. Huang, X.C. Meng, J. Shi, C.-X. Tang, X.W. Wu, H. Zha
TUB, Beijing, People's Republic of China

Thomson scattering x-ray source is an indispensable scientific X-ray imaging tool in various research fields. The 3-meter S-band linac in Tsinghua Thomson scatter-ing X-ray source (TTX) has been running at an accelerat-ing gradient of 15 MV/m so far. The gradient will be upgraded to 30MV/m by replacing the old structure with a shorter linac. Detailed optimization of the RF design of the new S-band linac structure is presented in this paper. Finally, further research on energy upgrade with X-band structures are also discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB070

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB082

Research of L-Band Disk-Loaded Waveguides Travelling Wave Accelerating Structures for a High Power Linac

cavity, bunching, electron, network

1506

Y.M. Zhang
USTC, SNST, Anhui, People's Republic of China
Y.J. Pei, L.S. Sheng, Y. Song
USTC/NSRL, Hefei, Anhui, People's Republic of China

L-band Electron Accelerator is widely used for industrial irradiation. This paper describes a constant-impedance, disk-loaded structure operating on the 2Pi/3 mode. The design details of L-band travelling wave accelerating structures are presented. All RF parameters in metal disk-loaded waveguides and fields were calculated. The SUPERFISH code was used to design the bunching and accelerating cavities. At the same time, we also calculated the beam dynamics. Some model cavities have been fabricated and experimental studies were carried on. In this study, some valuable results were obtained, which can provide a beneficial datum for the design and manufacture of L-band travelling-wave accelerating structures of 50MeV LINAC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB082

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB121

Bench Measurements and Beam Tests of a Prototype Stripline Kicker for Swap-Out Injection in the ALS-U

kicker, vacuum, injection, alignment

1599

S. De Santis, J.M. Byrd, T.H. Luo, G.C. Pappas, C. Steier, C.A. Swenson, W.L. Waldron
LBNL, Berkeley, California, USA

Funding: Work supported by the the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The ALS upgrade to a diffraction-limited light source (ALS-U Project) relies on a swap-out injection scheme, where the circulating current is maintained constant by injecting on-axis fresh bunch trains, replacing old trains, which are simultaneously extracted. The realization of a stripline kicker to perform such an operation presents several challenges in terms of optimal matching to the pulser, contributions to the beam coupling impedance, and dissipation of the power deposited by the stored beam. To test our design choices for the ALS-U kicker, we have built and installed on the ALS a kicker with characteristics similar to the design for the ALS-U, as the more challenging aspects of the project are concerned. In particular, while the small distance between stripline electrodes reduces the required pulser voltage, the extreme proximity of the circulating beam requires a careful evaluation of the interaction between beam and kicker. In this paper we present the first measurements with beam, after the test kicker installation, together with the results of bench measurements performed on a cold model and computer simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB121

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB132

A Novel Dual-Mode Dual-Frequency Linac Design

operation, cavity, network, distributed

1634

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

In this paper we will present a new type of accelerator structure that operates simultaneously at two accelerating modes with two frequencies. The frequencies are not harmonically related, but rather have a common sub-harmonic. This design will use a recently developed parallel-feeding network that feeds every cavity cell independently using a distributed feeding network. This will overcome many of the practical complications of coupled cell structure. We will provide the theoretical background for our dual-mode design as well as present our optimized design that operates at C and X bands simultaneously and provides enhanced gradient and efficiency compared to single-mode designs.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB132

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB143

Dependence of LEReC Beam Energy Spread on Photocathode Laser Modulation

laser, electron, space-charge, flattop

1669

S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, M.G. Minty, B. Sheehy, Z. Zhao
BNL, Upton, Long Island, New York, USA
B. Sheehy
Sheehy Scientific Consulting, Wading River, New York, USA

Present requirements to the photocathode DC gun of the low energy RHIC electron cooling (LEReC) project is to produce 100 ps long bunch of electrons with 130 pC charge. The laser pulse of required length will be produced with the stacking of multiple few picosecond long sub-pulses. Depending on the choice of the laser sub-pulse length and on the relative delay between these sub-pulses one can obtain laser pulse with various longitudinal intensity modulations. The longitudinal modulation of laser intensity creates longitudinal modulation of electron bunch charge. Such modulation is known to cause the growth of e-beam uncorrelated energy spread in photoinjectors - the effect we would like to avoid. In this paper we estimate growth of e-beam energy spread due to its initial density modulation and set requirements to the maximum allowable depth of longitudinal modulation of photocathode laser intensity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB143

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB148

Investigation of a Splitring-RFQ for High Current Ion Beams at Low Frequencies

rfq, resonance, simulation, ion

1680

M. Baschke, H. Podlech, A. Schempp
IAP, Frankfurt am Main, Germany

For hadron linacs RFQs are the first stage of acceleration. To reach high intensities a new Splitring-RFQ is investigated. Not only a high current and high beam quality/brilliance should be achieved, also a good tuning flexibility and comfort for maintenance are part of the study. It will consist of two stages with 27 MHz and 54 MHz to accelerate ions with an A/q of 60 up to energies of 200 keV/u. Therefor RF simulations with CST MWS were done to study the quality factor and the shunt impedance as well as tuning possibilities. First results and the status of the project will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB148

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK053

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

kicker, simulation, feedback, coupling

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK053

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK093

Sensitivity of the LHC Transverse Feedback System to Intra-Bunch Motion

feedback, pick-up, simulation, hardware

1916

G. Kotzian, W. Höfle, D. Valuch
CERN, Geneva, Switzerland

The LHC Transverse Feedback System is designed to damp and counteract all possible coupled bunch modes between the lowest betatron frequency and 20 MHz. The present study reveals that the analogue frontend processing scheme based on down converting the pick-up signal at the LHC RF frequency to baseband considerably extends the detected bunch movements visible to the feedback system to beyond 1 GHz. We develop an analytical model of the signal processing chain to explore the impact of even-symmetric and odd-symmetric intra-bunch movements on the detected beam position as a function of the longitudinal bunch shape. A set of equations is derived suitable for numerical simulations, or as a complement in particle tracking codes to further refine the behaviour of the LHC transverse feedback system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK093

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK105

The Design Improvement of Horizontal Stripline Kicker in TPS Storage Ring

kicker, storage-ring, vacuum, operation

1961

P.J. Chou, C.K. Chan, C.-C. Chang, K.T. Hsu, K.H. Hu, C.K. Kuan, I.C. Sheng
NSRRC, Hsinchu, Taiwan

We plan to replace the existing horizontal stripline kicker of the transverse feedback system with an improved design. Large reflected power was observed at the downstream port of stripline kicker driven by the feedback amplifier. A rapid surge of vacuum pressure was observed when we tested the high current operation in TPS storage ring in April 2016. A burned feedthrough of the horizontal stripline kicker was discovered during a maintenance shutdown. The improved design is targeted to reduce the reflection of driving power from feedback system and to reduce beam induced RF heating. This major modification of the design is described. The results of RF simulation performed with the electromagnetic code GdfidL are reported as well.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK105

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK122

Bunch-by-Bunch Feedback Kickers for SPEAR3

kicker, feedback, ion, vacuum

2012

K. Tian, W.J. Corbett, J.D. Fox, S.M. Gierman, R.O. Hettel, X. Huang, A.K. Krasnykh, N. Kurita, D.J. Martin, J.A. Safranek, J.J. Sebek
SLAC, Menlo Park, California, USA
Q. Lin
DongHua University, Songjiang, People's Republic of China
D. Teytelman
Dimtel, San Jose, USA

SPEAR3 operates with a large cross-section copper vacuum chamber, mode-damped RF cavities and low-impedance insertion devices. As a result, the beam is passively stable for 280-bunch circulating beam current up to 500ma when the background gas pressure is low. In the future, more small-gap insertion devices will be installed and plans are underway to implement resonant bunch-crabbing for the ultrafast x-ray research program. These requirements drive the need for a fast, bunch-by-bunch feedback system to control beam instabilities, remove unwanted satellite bunches and resonantly crab select bunches on demand. In this paper we present a conceptual design for the transverse bunch-by-bunch stripline kickers.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK122

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA019

Impact and Mitigation of Electron Cloud Effects in the Operation of the Large Hadron Collider

electron, cryogenics, operation, injection

2085

G. Iadarola, B. Bradu, P. Dijkstal, L. Mether, G. Rumolo
CERN, Geneva, Switzerland

In 2015 and in 2016 the Large Hadron Collider has been routinely operated with 25 ns bunch spacing. With this beam configuration electron clouds develop in a large fraction of the beam chambers, in spite of a very large electron dose accumulated on the surfaces. This posed several challenges to different aspects of the beam operation. In particular, the machine settings had to be optimized in order to mitigate coherent and incoherent effects of the electron cloud on the beam dynamics while a specifically designed feed-forward control had to be implemented and optimized in order to dynamically adapt the regulations of the cryogenic system to the strong heat load deposited by the electron cloud on the beam screens of the cryogenic magnets. At the same time, the data collected from the different accelerator subsystems (heat loads, vacuum pressures, evolution of the bunch by bunch beam parameters) allowed to significantly improve our models and understanding on these phenomena.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA068

The New Injector Design for MYRRHA

cavity, simulation, emittance, rfq

2234

K. Kümpel, P. Müller, D. Mäder, N.F. Petry, H. Podlech
IAP, Frankfurt am Main, Germany

The MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) Project is a planned accelerator driven system (ADS) for the transmutation of long-living radioactive waste. A critical passage for the beam quality and especially for the emittance is the injector. Therefore, a new injector design with improved beam dynamics has been developed, featuring low emittance growth rates while using only room temperature structures. The previous design consisted of a 4-Rod RFQ, 7 room temperature and 5 superconducting CH-DTL cavities and 2 rebuncher cavities, whereas the superconducting cavities in the new design have been replaced by 8 room temperature CHs and an additional rebuncher. The main challenge during the development is achieving the required reliability to reduce the thermal stress inside the planned reactor. Therefore, simulations with CST MICROWAVE STUDIO have been made to compare several cooling concepts and to optimize the cavities, especially in terms of the shunt impedance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA068

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA069

Test of a High Power Room Temperature CH DTL Cavity

cavity, operation, coupling, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA069

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA080

Stochastic Cooling Hardware for Low Energy Deuterons at COSY

pick-up, kicker, experiment, electron

2261

B. Breitkreutz, R. Greven, N. Shurkhno, R. Stassen, H. Stockhorst
FZJ, Jülich, Germany

One of the central utilizations of the COSY facility nowadays is to host experiments for the JEDI (Jülich Electric Dipole moment Investigations) collaboration. These experiments use polarized deuteron beams at momenta below 1 GeV/c, that are stored for several minutes. In order to increase the spin coherence time, beam cooling is necessary. Electron cooling is applied to pre-cool the beam, but the solenoids of the electron cooler may not be perfectly compensated. Thus, stochastic cooling would be desirable instead. Unfortunately, the existing stochastic cooling system is not sensitive at low beam velocities. This paper presents newly developed stochastic cooling pickups and kickers for a system dedicated to low beam velocities of approximately 0.5c. The design is based on the slot-ring type pickups that have been developed for the High Energy Storage Ring (HESR), but optimized for low particle velocities and a low frequency band of 350-700 MHz. Since the structures get much bigger in comparison to the HESR version, mechanical properties must be reconsidered and a trade-off between electrical properties, cooling performance and constructability must be found.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA080

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA085

First Experiences with HESR Stochastic Cooling System

kicker, pick-up, hardware, ion

2278

R. Stassen, B. Breitkreutz, T. Katayama, N. Shurkhno, H. Stockhorst
FZJ, Jülich, Germany
T. Katayama
Nihon University, Narashino, Chiba, Japan
L. Thorndahl
CERN, Geneva, Switzerland

The stochastic cooling system of the HESR (High Energy Storage Ring) is based on completely new structures especially designed for the HESR. Each beam surrounding slot of these so called slot-ring couplers covers the whole image current without a reduction of the HESR aperture and without any plunging system. One pickup and one kicker have been already fabricated and installed into the COSY ring to demonstrate stochastic cooling in all three dimensions with only one structure. First results of commissioning with proton beams will be presented. The longitudinal cooling system at HESR is based on filter cooling with an optical notch-filter and ToF cooling. The demanding accuracy concerning phase stability requires dedicated control of the notch-frequency. The optical COSY filter has been modified and can be proven in long term runs together with the new stochastic cooling system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA085

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA092

An Upgrade Scenario of RF System to Achieve 1.6 MW Beam Acceleration in J-PARC RCS

cavity, power-supply, resonance, acceleration

2297

M. Yamamoto, M. Nomura, T. Shimada, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan

The J-PARC RCS has successfully accelerated 1 MW equivalent proton beam. However, the beam commissioning results and the particle tracking simulation suggest that the RCS has possibility to accelerate up to 1.6 MW beam. Since the power supply of the rf system almost reaches the limit under the condition of 1 MW beam, we consider the possible upgrade scenario of the rf system to accelerate 1.6 MW beam.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA092

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPVA094

Beam Dynamics Design of the Muon Linac High-Beta Section

linac, simulation, emittance, target

2304

Y. Kondo, K. Hasegawa
JAEA/J-PARC, Tokai-mura, Japan
R. Kitamura
University of Tokyo, Tokyo, Japan
T. Mibe, M. Otani, M. Yoshida
KEK, Tsukuba, Japan

Funding: This work was supported by JSPS KAKENHI Grant Number 16H03987.
A muon linac development for a new muon g-2 experiment is now going on at J-PARC. Muons from the muon beam line (H-line) at the J-PARC MLF are once stopped in an silica aerojel target and room temperature muoniums are evaporated from the aerogel. They are dissociated with laser (ultra slow muons), then accelerated up to 212 MeV using a linear accelerator. For the accelerating structure from 40 MeV, disk-loaded traveling-wave structure is applicable because the particle beta is more than 0.7. The structure itself is similar to that for electron linacs, however, the cell length should be harmonic to the increase of the particle velocity. In this paper, the beam dynamics design of this muon linac using the disk-loaded structure is described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA094

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEOAB3

RF Quadrupole Structures for Transverse Landau Damping in Circular Accelerators

quadrupole, damping, simulation, collider

2516

M. Schenk, X. Buffat, L.R. Carver, A. Grudiev, K.S.B. Li, E. Métral, K. Papke
CERN, Geneva, Switzerland
A. Maillard
ENS, Paris, France

The beams required for the high luminosity upgrade of the Large Hadron Collider (HL-LHC) and other potential future circular colliders (FCC) call for efficient mechanisms to suppress transverse collective instabilities. In addition to octupole magnets installed for the purpose of Landau damping in the transverse planes, we propose to use radio frequency (rf) quadrupole structures to considerably enhance the aforementioned stabilising effect. By means of the PyHEADTAIL macroparticle tracking code as well as analytical studies, the stabilising mechanism introduced by an rf quadrupole is studied and explained. It is, furthermore, compared to the influence of the second order chromaticity on transverse beam stability.

Slides WEOAB3 [2.537 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOAB3

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB115

Normal Conducting CW Transverse Crab Cavity For Producing Short Pulses In SPEAR3

cavity, HOM, damping, photon

2840

Z. Li, V.A. Dolgashev, M. Dunham, K.J. Gaffney, R.O. Hettel, X. Huang, N. Kurita, J.A. Safranek, J.J. Sebek, K. Tian
SLAC, Menlo Park, California, USA

Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515.
The ability to produce short pulse X-rays on the scale of 1-10 ps fwhm in the SPEAR3 storage ring light source would enable enhanced timing mode studies of dynamic processes in materials as they occur. The crab cavity approach appears to be optimal for SPEAR3 to produce short pulse X-rays. Furthermore, by using a two-frequency crabbing scheme, SPEAR3 would be able to produce short-pulse bunches while supplying the high average flux needed for regular users. While supercon-ducting RF (SCRF) technology could be a natural choice for the CW crab cavity, the deflecting voltage for SPEAR3 crabbing appears to be within reach of more affordable normal conducting RF (NCRF). In this paper, we present a preliminary NCRF CW crab cavity design for SPEAR3.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB115

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK009

Collimators for SuperKEKB Main Ring

background, factory, positron, HOM

2929

T. Ishibashi, Y. Suetsugu, S. Terui
KEK, Ibaraki, Japan

SuperKEKB, which is an upgrade project of KEKB, is an electron-positron collider with extremely high luminosity. Collimators (movable masks) for SuperKEKB have been designed to fit an antechamber scheme of the vacuum system and will be operated to improve backgrounds in the particle detector named Belle II. We are developing two types of collimators; a horizontal and vertical collimator. The collimator has a pair of horizontally or vertically opposed movable jaws with RF fingers. Each jaw travels independently through 5-25 mm horizontally or 2-12 mm vertically in a distance between the beam axis and the tip of the jaw. SuperKEKB will operate with high currents of short bunch lengths, therefore it is important to estimate and decrease the impedance of the collimators. Two horizontal collimators were already installed in the positron ring and operated during Phase-1 commissioning for approximately 5 months, from February to June 2016. In this presentation, the latest design, and the results in the Phase-1 commissioning are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK009

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK014

Coupled Bunch Instability and Its Cure at J-PARC RCS

kicker, space-charge, emittance, injection

2946

Y. Shobuda, H. Harada, H. Hotchi, P.K. Saha, T. Takayanagi, F. Tamura, N. Tani, T. Togashi, Y. Watanabe, K. Yamamoto, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y.H. Chin, Y. Irie, T. Toyama
KEK, Ibaraki, Japan

The RCS at J-PARC is a kicker-impedance dominant machine, which violates the impedance budget from a classical viewpoint. Nevertheless, we have recently succeeded to accelerate a 1-MW equivalent beam by making maximum use of the space charge effect on the beam instabilities. In this report, we explain the manipulation to suppress the beam instability, at first. Then, we discuss some issues to suppress the beam instabilities for beams with much smaller transverse emittance, as well as the present status of our efforts to reduce the kicker impedance toward the realization of the higher beam power at the RCS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK014

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK054

Evaluation and Attenuation of Sirius Components Impedance

HOM, dipole, storage-ring, vacuum

3048

H.O.C. Duarte, L. Liu, S.R. Marques
LNLS, Campinas, Brazil

The Sirius in-vacuum components have their design improvements, possibilities and choices presented, where wake heating, single-bunch and multi-bunch effects and mechanical aspects were taken into account. The results were finally evaluated and added to the Sirius impedance budget.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK054

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK055

Analysis and Countermeasures of Wakefield Heat Losses for Sirius

HOM, simulation, vacuum, storage-ring

3052

H.O.C. Duarte, L. Liu, S.R. Marques, T.M. da Rocha, F.H. de Sá
LNLS, Campinas, Brazil

Design evaluation and possible solutions for several in-vacuum components of Sirius are presented, having their impedance analysis focused on mitigating the wake heating impact. Thermal and/or structural simulation of the models are carried out by considering the heat load directly obtained from wakefield simulations with resistive wall boundary conditions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK055

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK058

Preliminary Longitudinal Impedance Model for the ESRF-EBS

vacuum, simulation, undulator, storage-ring

3063

S.M. White
ESRF, Grenoble, France

In light sources, longitudinal beam coupling impedance can deteriorate performance through bunch lengthening or increased longitudinal emittance due to the microwave instability. Simulation estimates are therefore required to devise the appropriate counter-measures if necessary. The main contributors to the longitudinal impedance model of the new ESRF-EBS storage ring were simulated. A preliminary longitudinal impedance model is presented and preliminary tracking simulations are shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK058

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK066

Calculation of Wakefields and Higher Order Modes for the Vacuum Chamber of the CMS, ATLAS, ALICE and LHCb Experiments for the HL-LHC

wakefield, vacuum, higher-order-mode, dipole

3081

R. Wanzenberg, O. Zagorodnova
DESY, Hamburg, Germany
E. Métral, B. Salvant
CERN, Geneva, Switzerland

Funding: Partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The High Luminosity Large Hadron Collider (HL-LHC) project was started with the goal to extend the discovery potential of the Large Hadron Collider (LHC). The HL-LHC study implies also upgraded dimensions of the experimental beam pipes of the CMS, ATLAS, ALICE and LHCb experiments. The trapped monopole and dipole Higher Order Modes (HOMs) and the short range wakefields for the new design of the vacuum chambers were calculated with help of the computer codes MAFIA and ECHO2D. The results of the short range wakefields calculations and the HOMs calculations are presented in this report. The short range wakefields are presented in terms of longitudinal and transverse wake potentials and also in terms of loss and kick parameters. Selected results from the HOMs calculations , including the the frequency, the loss parameter, the R/Q and the Q value are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK066

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK071

Resistive-Wall Impedance Effects for the New KEK Light Source

vacuum, betatron, feedback, storage-ring

3095

N. Nakamura
KEK, Ibaraki, Japan

KEK Light Source (KEK-LS) is a 3-GeV storage ring of 20-cell HMBA (Hybrid Multi-Bend Achromat) lattice*, which is planned to be constructed as a successor of the two existing Photon Factory storage rings (PF ring and PF-AR) in the KEK Tsukuba Campus. In this ring, a lot of in-vacuum undulators with a small magnetic gap (4 mm at minimum) will be installed and the vacuum pipe of a small aperture (25 mm in diameter) will be used. In addition, NEG coating, having a low electric conductivity, will be utilized for the vacuum pipe to ensure a sufficient beam lifetime early in the machine commissioning. In this paper, the heating power due to the longitudinal RW impedance and the growth rate of coupled-bunch instability caused by the transverse RW impedance are calculated and the effects of the RW impedance on KEK-LS are presented.
* K. Harada et al., Proc. of IPAC2016, Busan, Korea, pp.3251-3253; K. Harada et al., these proceedings.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK071

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK078

Development of the Impedance Model in HEPS

vacuum, kicker, injection, feedback

3110

N. Wang, Z. Duan, X.Y. Li, H. Shi, S.K. Tian, G. Xu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a new designed photon source at beam energy of 6 GeV. Due to the small beam pipe aperture and a large number of insertion devices in the machine, the impedance can drive collective instabilities and limit the machine performance. Therefore, a thorough estimation of the coupling impedance is necessary in controlling the total impedance of the whole machine. A primary impedance model is obtained for the storage ring.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK078

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK081

The Logitudinal Broadband Impedance and Energy Spread Measurements at the VEPP-4M Electron-Positron Collider

electron, synchrotron, collider, scattering

3117

V.M. Borin, V.A. Kiselev, G.Y. Kurkin, S.A. Nikitin, P.A. Piminov, S.V. Sinyatkin
BINP SB RAS, Novosibirsk, Russia
V.L. Dorokhov, O.I. Meshkov
BINP, Novosibirsk, Russia

The paper presents measurements of the longitudinal broadband impedance and beam energy spread of the beam at the VEPP-4M electron-positron collider in an energy range of 1.0 - 3.5 GeV. In order to measure the longitudinal bunch size at various beam currents we used PS-1/S1 streak camera with picosecond temporal resolution. The dependence of bunch length from the bunch current at different energies demonstrates a microwave instability threshold. The bunch lengthening was caused by potential well distortion as well. Potential well distortion lengthening was used to estimate a value of the reactive part of the longitudinal impedance of the vacuum chamber of the collider Observed microwave instability thresholds was used to measure the value of the broadband impedance. The impact of the Touschek effect in the beam energy spread is discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK081

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK087

Measurement and Characterization of Cable Losses for High Voltage Coaxial Cables Used in Kicker Systems

kicker, simulation, network, injection

3131

A. Ferrero Colomo, L. Ducimetière, T. Kramer, L. Sermeus
CERN, Geneva, Switzerland

In the framework of CERN's LHC Injector Upgrade, simulation models for kicker pulse generators have been improved. A key element in the conventional pulse generators, among many others, are the high voltage coaxial cables. Since they can have significant impact on the waveform characteristics, an accurate cable model for simulation is crucial for reliable results during development. For this purpose, precise measurements of scatter parameters have been carried out in order to improve existing simulation models. Specialized high voltage cables, sometimes SF6 gas filled, used in various CERN kicker systems are usually large, heavy, not very flexible and often only one end is easy accessible. In addition, the impedance of these cables is rarely of 50 Ohms, which presents an extra difficulty. This paper describes the methods that have been defined and used to measure any kind of coaxial structures relying on S11 parameters exclusively. Measurements for various specialized cable types are presented and compared with their improved models. The implications for overall kicker system performance are briefly discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK087

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK089

Characterization of Resonant Impedances of CERN-SPS Gate Valves

simulation, resonance, coupling, 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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK090

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

shielding, vacuum, resonance, coupling

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK090

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK094

LEIR Impedance Model and Coherent Beam Instability Observations

ion, injection, space-charge, electron

3159

N. Biancacci, H. Bartosik, A. Huschauer, E. Métral, T.L. Rijoff, B. Salvant, R. Scrivens
CERN, Geneva, Switzerland
M. Migliorati
University of Rome La Sapienza, Rome, Italy

The LEIR machine is the first synchrotron in the ion acceleration chain at CERN and it is responsible to deliver high intensity ion beams to the LHC. Following the recent progress in the understanding of the intensity limitations, detailed studies of the machine impedance started. In this work we describe the present LEIR impedance model, detailing the contribution to the total longitudinal and transverse impedance of several machine element. We then compare the machine tune shift versus intensity predictions against measurements at injection energy and summarize the coherent instability observations in absence of transverse damper feedback.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK094

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK095

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

coupling, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK095

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK096

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

simulation, coupling, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK096

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK100

The Applicability of NEG Coated Undulator Vessels for the CLARA FEL Test Facility

vacuum, FEL, wakefield, undulator

3181

O.B. Malyshev, K.B. Marinov, K.J. Middleman, N. Thompson, R. Valizadeh, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
O.B. Malyshev, K.J. Middleman, N. Thompson, R. Valizadeh, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom

CLARA is a FEL test facility at Daresbury Laboratory (DL), UK. The undulator vacuum chamber is 20 m long with inner diameter 6 mm and its vacuum performance can benefit from a NEG coating. The thickness of the coating layer must be carefully optimised. A layer ~ 1 um would help the vacuum but a thinner layer would be partially transparent for the EM field reducing the resistive wall wakefields due to the NEG. A very thin layer, however, may not yield the necessary vacuum performance. Two types of NEG coatings produced at DL - dense and columnar - were considered. Their bulk conductivities were measured in a separate study. The resistive wall wakefield impedance was calculated following the standard approach for multilayer vessels. A 250 fs rms electron bunch was generated in ASTRA and its wakefield was obtained from the vessel impedance. The FEL performance was then studied through GENESIS simulations and the result compared to the case with no wakefields. It was found that NEG layers thicker than 100 nm give an unacceptable reduction of the FEL power and the vacuum performance of such thin coatings is unknown. Possible solutions to this problem are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK100

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK106

Impedance and Collective Effects for the Advanced Light Source Upgrade at LBNL

simulation, wakefield, cavity, vacuum

3192

S. Persichelli, J.M. Byrd, S. De Santis, D. Li, T.H. Luo, C. Steier, M. Venturini
LBNL, Berkeley, California, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The upgrade of the Advanced Light Source (ALS-U) consists of a multiband achromat ultralow emittance lattice for the production of diffraction-limited soft x-rays. A very important issue for ALS-U is represented by instabilities induced by wakefields, that may limit the peak current of individual bunches and the total beam current. In addition, vacuum chamber apertures of few millimeters, that are a key feature of low-emittance machines, can result in a significant increase in the Resistive Wall (RW) impedance. In this paper we present progress on establishing short range wakefield model for ALS-U and evaluating the impact on the longitudinal and transverse single-bunch dynamics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK106

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK113

Entrance and Exit CSR Impedance for Non-Ultrarelativistic Beam

wakefield, dipole, bunching, FEL

3214

R. Li
JLab, Newport News, Virginia, USA
C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA

Funding: Work supported by the Department of Energy, Laboratory Directed Research and Development Funding, under Contract No. DE-AC05-06OR23177
For a high-brightness electron beam being transported through beamlines involving bending systems, the coherent synchrotron radiation (CSR) and longitudinal space charge (LSC) interaction could often cause microbunching instability. The semi-analytical Vlasov solver for microbunching gain* depends on the impedances for the relevant collective effects. The existing results for CSR impedances are usually obtained for the ultrarelativistic limit. To extend the microbunching analysis to cases of low energies, such as the case of an ERL merger, or to density modulations at extremely small wavelength, it is necessary to extend the impedance analysis to the non-ultrarelativistic regime. In this study, we present the impedance analysis for the transient CSR interaction in the non-ultrarelativistic regime, for transients including both entrance to and exit from a magnetic dipole. These impedance results will be compared to their ultra-relativistic counterparts**, and the corresponding wakefield obtained from the impedance for low-energy beams will be compared with the existing results of transient CSR wakefield for general beam energies***.
* C.-Y. Tsai et al., Proc. of IPAC'15, 596 (2015).
** C. Mitchell et al ., Proc. of IPAC'13, 1832 (2014).
*** E. L. Saldin et al ., Nucl. Instrum. Meth. A 398, 373 (1997).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK113

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA022

RECENT TWO-BEAM ACCELERATION ACTIVITIES AT ARGONNE WAKEFIELD ACCELERATOR FACILITY

acceleration, experiment, accelerating-gradient, wakefield

3305

J.H. Shao, S.P. Antipov, M.E. Conde, W. Gai, Q. Gao, G. Ha, W. Liu, N.R. Neveu, J.G. Power, Y.R. Wang, E.E. Wisniewski, L.M. Zheng
ANL, Argonne, Illinois, USA
C.-J. Jing, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA
J. Shi, D. Wang
TUB, Beijing, People's Republic of China

The Two-Beam Acceleration (TBA) is a modified approach to the structure-based wakefield acceleration which may meet the luminosity, efficiency, and cost requirement of a future linear collider. Recently, various TBA experiments have been carried out at the Argonne Wakefield Accelerator Facility (AWA). With X-band metallic power extractors and accelerators, a 70 MeV/m average accelerating gradient has been demonstrated in two stages while a 150 MeV/m gradient as well as 300 MW extracted power have been achieved in a single stage. In addition, low cost K-band dielectric power extractor and accelerator have also been developed. The preliminary results show power extraction of 55 MW and an average accelerating gradient of 28 MeV/m.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA024

Design of an Inductive Adder for the FCC Injection Kicker Pulse Generator

kicker, injection, high-voltage, collider

3312

D. Woog, M.J. Barnes, L. Ducimetière, J. Holma, T. Kramer
CERN, Geneva, Switzerland

The injection system for a 100 TeV centre-of-mass collider is an important part of the Future Circular Collider (FCC) study. Due to issues with conventional kicker systems, such as self-triggering and long term availability of thyratrons and limitations of HV-cables, innovative design changes are planned for the FCC injection kicker pulse generator. An inductive adder (IA) based on semiconductor (SC) switches is a promising technology for kicker systems. Its modular design, and the possibility of an active ripple suppression are significant advantages. Since the IA is a complex device, with multiple components whose characteristics are important, a detailed design study and construction of a prototype is necessary. This paper summarizes the system requirements and constraints, and describes the main components and design challenges of the prototype IA. It outlines the results from simulations and measurements on different magnetic core materials as well as on SC switches. The paper concludes on the design choices and progress for the prototype to be built at CERN.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA024

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA036

The LHC Injectors Upgrade (LIU) Project at CERN: Proton Injector Chain

linac, cavity, injection, proton

3335

K. Hanke, J. Coupard, H. Damerau, A. Funken, B. Goddard, A.M. Lombardi, D. Manglunki, S. Mataguez, M. Meddahi, B. Mikulec, G. Rumolo, R. Scrivens, E.N. Shaposhnikova, M. Vretenar
CERN, Geneva, Switzerland

The LHC Injectors Upgrade (LIU) project at CERN aims at delivering high brightness beams required by the LHC in the high-luminosity LHC (HLLHC) era. The project comprises a new H⁻ Linac (Linac4) as well as a massive upgrade of the PS Booster, PS and SPS synchrotrons. This paper gives an update of the activities regarding the proton injector chain. We present the target beam parameters, a brief status of the upgrade work per machine and the outcome of the recent reviews. The planning for the implementation of the hardware upgrades and the re-commissioning of the complex will also be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA036

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA047

Input Signal Generation for Barrier Bucket RF Systems at GSI

cavity, synchrotron, storage-ring, operation

3359

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

At the GSI facility in Darmstadt, Germany, Barrier Bucket RF systems are currently designed for the SIS 100 synchrotron (part of the future FAIR facility) and the Experimental Storage Ring (ESR). The purpose of these systems is to provide single sine voltage pulses at the cavity gap. Due to the high requirements regarding the gap signal quality, the calculation of the pre-distorted input signal plays a major role in the system development. A procedure to generate the input signal based on the dynamic properties in the linear region of the system has been developed and tested at a prototype system. It was shown that this method is able to generate single sine gap signals of high quality in a wide voltage range. As linearity can only be assumed up to a certain magnitude, nonlinear effects limit the quality of the output signal at very high input levels. An approach to overcome this limit is to extend the input signal calculation to a nonlinear model of the system. In this contribution, the current method to calculate the required input signal is presented and experimental results at a prototype system are shown. Additionally, first results in the nonlinear region are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA047

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA060

Construction of the New Kicker Magnet Systems for PF-Advanced Ring

kicker, injection, timing, power-supply

3401

A. Ueda, S. Asaoka, T. Honda, S. Nagahashi, N. Nakamura, T. Nogami, H. Takaki, T. Uchiyama
KEK, Ibaraki, Japan

From July 2016 we are constructing a new beam transport (BT) line for the Photon Factory Advanced Ring (PF-AR). The new BT line was designed to transport the full energy 6.5-GeV beam directly from the LINAC, and the top up injection will be possible for the PF-AR. We designed and produced new kicker systems for this project. Three kicker magnets are used for the injection of the 6.5-GeV beam. The kicker magnets were designed as a window frame type ferrite core magnet. The magnetic fields of these magnets have been measured by the search coil method. We paid attention to evaluating eddy current losses of the metal coated ceramic duct in the magnetic field measurement.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA060

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA094

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

kicker, injection, simulation, coupling

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

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA094

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA095

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

kicker, injection, coupling, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA095

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA097

Upgrading the SPS Fast Extraction Kicker Systems for HL-LHC

kicker, electron, extraction, resonance

3483

M.J. Barnes, M.S. Beck, H.A. Day, L. Ducimetière, E. Garcia-Tabares Valdivieso, B. Goddard, H. Neupert, A. Romano, L. Vega Cid, W.J.M. Weterings
CERN, Geneva, Switzerland
C. Zannini
ADAM SA, Geneva, Switzerland

The CERN SPS has two fast extraction systems, each consisting of travelling wave kicker magnets (MKEs). The beam induced heating in the ferrite yoke of these magnets was historically kept to an acceptable level by implementing water cooling of the kicker magnets: in addition serigraphy was applied on the surfaces of the ferrite yoke facing the beam. Nevertheless, high intensity beams needed in the future for HL-LHC will significantly increase the beam induced heating, potentially raising the MKE ferrite yoke temperature to its Curie point. Hence detailed studies of longitudinal beam coupling impedance were carried out to identify simple but effective methods of further reducing beam induced power deposition. Based on the results of these studies, and in the framework of the LHC Injectors Upgrade (LIU) project, an upgraded MKE kicker magnet was installed during the 2015-2016 shutdown. This paper reports and compares results of predictions, laboratory measurements, temperature measurements during SPS operation, and machine development studies. Measurements of both dynamic pressure rise in the upgraded magnet and Secondary Electron Yield, on samples, are also reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA097

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA099

Influence of Conducting Serigraphy Upon Field Pulse Shape of the SPS Extraction Kicker Systems

kicker, flattop, extraction, high-voltage

3491

A. Adraktas, M.J. Barnes, L. Ducimetière
CERN, Geneva, Switzerland

Fast pulsed magnets with ferrite yokes are used for beam extraction from the CERN SPS accelerator. These kickers are transmission line type magnets with a rectangular shaped aperture through which the beam circulates. Unless special precautions are taken, the beam impedance of the yoke can provoke significant induced heating, especially for high intensity beams. Previous upgrades of the SPS extraction kicker magnets have included silver fingers serigraphed on the surface of the ferrite facing the beam, to help shield the ferrite yoke from circulating beam. Beam based measurements of the extracted beam indicated that the serigraphy may influence the shape of the field pulse, causing it to increase slightly in magnitude during the flat-top. Hence theoretical studies have been carried out to determine whether the serigraphy influences the field pulse: these studies are reported in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA099

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA100

Operational Experience of the Upgraded LHC Injection Kicker Magnets During Run 2 and Future Plans

injection, kicker, electron, vacuum

3495

M.J. Barnes, A. Adraktas, G. Bregliozzi, L. Ducimetière, B. Goddard, B. Salvant, J. Sestak, L. Vega Cid, W.J.M. Weterings, C. Yin Vallgren
CERN, Geneva, Switzerland

During Run 1 of the LHC, one of the injection kicker magnets caused occasional operational delays due to beam induced heating with high bunch intensity and short bunch lengths. In addition, there were also sporadic issues with vacuum activity and electrical flashover of the injection kickers. An extensive program of studies was launched and significant upgrades were carried out during Long Shutdown 1 (LS 1). These upgrades included a new design of beam screen to reduce both beam coupling impedance of the kicker magnet and the electric field associated with the screen conductors, hence decreasing the probability of electrical breakdown in this region. This paper presents operational experience of the injection kicker magnets during the first years of Run 2 of the LHC, including a discussion of faults and kicker magnet issues that limited LHC operation. In addition, in light of these issues, plans for further upgrades are briefly discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA100

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA101

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

coupling, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA101

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA108

Operational Feedback and Analysis of Current and Future Designs of the Injection Protection Absorbers in the Large Hadron Collider at CERN

injection, vacuum, operation, alignment

3517

D. Carbajo Perez, N. Biancacci, C. Bracco, G. Bregliozzi, M. Calviani, M.I. Frankl, L. Gentini, S.S. Gilardoni, G. Iadarola, I. Lamas Garcia, A. Lechner, A. Perillo-Marcone, B. Salvant
CERN, Geneva, Switzerland

Two injection protection absorbers, so-called TDIs (Target Dump Injection), are installed close to Interaction Points IP2 and IP8 of the Large Hadron Collider (LHC) right downstream of the injection kicker magnets (MKI). Malfunction or timing errors in the latter lead to wrong steering of the beam, which must then be intercepted by the TDI to avoid downstream equipment (which includes superconducting magnets) damage. In recent years, MKI failures during operation have brought to light opportunities for improvement of the TDI. The upgrade of this absorber, so-called TDIS (where S stands for segmented), is conceived as part of the High Luminosity-LHC (HL-LHC) project and those operational issues are taken into account for its design. The present document describes not only the aspects related to the current TDI performance and their impact in its successor's design but also the key modifications to cope with the stronger requirements associated to the higher luminosity goal.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA108

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA121

Thermal Experimet Results on TPS Beam Position Monitors

simulation, cavity, storage-ring, vacuum

3554

Y.T. Huang, C.K. Chan, J. -Y. Chuang, I.C. Sheng, Y.C. Yang
NSRRC, Hsinchu, Taiwan

Beam position monitors mounted in straight sections exhibit an unusual temperature rise which is attributed to poor thermal and electrical conductivity of the stainless steel BPM chamber, to the vicinity to RF-bellows, and the large button electrode size to get superior signal levels. Thermocouples tied to BPM flanges and RF bellows show that the temperature could reach 50 oC when storing a beam current of 400 mA and BPMs located between two RF-bellows in RF cavity sections responds by even 5-10 oC higher values than average. To resolve this issue, off site experiments and simulations were conducted to further understand the heat flow in the whole structure. In this paper we discuss more details of these studies.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA121

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA129

Arc-Flash Hazard and Protection for Electric Switchboard at NSRRC

detector, site, photon, power-supply

3571

T.-S. Ueng, Y.F. Chiu, C.K. Kuan, K.C. Kuo, Y.-C. Lin
NSRRC, Hsinchu, Taiwan

During the operation of electrical equipment the arc-flash accident could damage the equipment and endanger the working personnel. In order to prevent this type of accidents from happening and to minimize the damages, a delicate setup is being installed inside the electric switchboard for suppressing the accidents at the initial stage of arcing at NSRRC's power system. The installed device includes the arc sensor, the smoke detector, the high rupturing capacity fuse, the circuit breaker and the protection relay. Further improvement on preventing the arc-flash accidents is also under study.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA129

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA131

Single-Inductor Bipolar Outputs Power Converters

power-supply, controls, electronics, operation

3577

Y.T. Li, C.Y. Liu, K.-B. Liu, B.S. Wang, Y.S. Wong
NSRRC, Hsinchu, Taiwan

In the circuit design for electronic products, bipolar power supply is often required. A non-isolated dual polarity power supply design is using two inductors to achieve this function. The number of inductors on the circuit would increase both the cost of products and space requirement. So the use of a single inductor bipolar power converter design can effectively reduce the cost and space to enhance product competitiveness. In this paper, the principle of a new single-inductor bipolar power converter will be described and tested to prove the feasibility of this design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA131

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA134

Impedance Measurement of Vacuum Chamber Components for the Advance Photon Source (APS) Upgrade

simulation, cavity, vacuum, photon

3583

M.P. Sangroula
IIT, Chicago, Illinois, USA
R.M. Lill, R.R. Lindberg, X. Sun
ANL, Argonne, Illinois, USA

Funding: U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC0206CH11357.
The proposed Advance Photon Source Upgrade (APS-U) employs a multi-bend achromat (MBA) lattice to increase the photon brightness by two to three orders of magnitude. One of the main design challenges of the upgrade is to minimize rf heating and collective instabilities associated with the impedance of small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. Here, we present the summary of the impedance contributions for the APS-U and describe our planned impedance measurement technique, including some measurement results for the non-evaporative getter (NEG)-coated copper chamber and simulation results for other critical components using a novel Goubau line (G-line) set up.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA134

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPVA141

Ion Cyclotron Resonance Heating Transmitter Opening Switch Upgrade

operation, plasma, high-voltage, resonance

3600

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

Diversified Technologies Inc. (DTI) has installed a high-power solid-state opening switch upgrade package to replace the mercury ignitron crowbars in the Ion Cyclotron Resonance Heating (ICRH) Transmitters at MIT Plasma Fusion Science Center's (PFSC) Alcator C Mod, a Tokamak-type fusion experimental device. The speed of the series opening switch avoids the large fault currents on the transformer and power feed inherent with a crowbar. This improvement enables re-optimization of the Transformer/Rectifier (T/R) set, ultimately allowing increased power output and increased tetrode reliability. The ratings of the prior high voltage power supply are a compromise between high output power (lower impedance required from the T/R set) and crowbar reliability (higher impedance required from the power supply to limit fault current). DTI's opening switch upgrade safely allows the use of significantly reduced transformer impedance and lower droop, giving increased power as well as improved tube protection. DTI's opening switch kit can readily be adapted to any similar transmitters as an upgrade from a crowbar.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA141

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB002

Update of the Collective Effects Studies for Sirius

simulation, radiation, undulator, operation

3680

F.H. de Sá, H.O.C. Duarte, L. Liu
LNLS, Campinas, Brazil

An updated impedance budget for Sirius, with contributions from 3D electromagnetic simulations and analytic calculations, is presented and the estimates for single and multi-bunch instability thresholds for the first operation phase are re-evaluated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB002

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB003

Harmonic RF System for the ESRF EBS

cavity, simulation, beam-loading, synchrotron

3684

N. Carmignani, J. Jacob, B. Nash, S.M. White
ESRF, Grenoble, France

A harmonic RF system for bunch lengthening to increase the Touschek lifetime of the ESRF Extemely Brilliant Source (EBS) is under study. Multiparticle simulations have been performed to study the bunch lengthening and the bunch shape with impedance effect and with third or fourth harmonic cavities. The effect of a harmonic RF system on the microwave instability is studied, finding an increase in the threshold. The AC Robinson instability threshold with a superconducting harmonic cavity has been studied with multiparticle simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB005

Improvement of the Analytic Vlasov Solver DELPHI

simulation, synchrotron, proton, hadron

3688

D. Amorim
Université Grenoble Alpes, Grenoble, France
N. Biancacci, K.S.B. Li, E. Métral
CERN, Geneva, Switzerland

The simulation code DELPHI is an analytic Vlasov solver which allows to evaluate the beam transverse stability with respect to impedance effects. It allows to perform fast scans over parameters such as chromaticity, damper gain or beam intensity for a given impedance model and particle distribution. In order to improve the simulation code, new longitudinal particle distributions have been implemented. The simulations results obtained with these distributions are compared to theoretical predictions. An additional post-processing of DELPHI's output has also been implemented, allowing to reconstruct the signal seen by head-tail stripline monitors, in particular in presence of bunch-by-bunch damper. The results are compared to theoretical models, to pyHEADTAIL simulations and to measurements performed in the LHC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB005

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB020

Coupling Impedances and Collective Effects for FCC-ee

vacuum, collective-effects, coupling, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB020

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB025

Simulation Studies of Transverse Beam Instabilities and Measures Beyond 1 MW Beam Power in the 3-GeV RCS of J-PARC

simulation, injection, acceleration, extraction

3750

P.K. Saha, H. Hotchi, Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The transverse impedance of the extraction kicker magnets is a significant beam instability source in the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex). The systematic simulation studies for beam instability by including the space charge effect has been done by using the ORBIT code. The simulation results are well reproduced in the corresponding measurements. The designed 1 MW beam power has recently been accomplished by keeping sextuple magnets off in order to stabilize the beam by utilizing the large lattice chromaticity throughout the entire acceleration period. The RCS simultaneously delivers extracted beam to the MLF (Material and Life Science Experimental Facility) and the MR (Main Ring). In order to ensure 1 MW beam power at the MLF even when RCS beam sharing to the MR is twice increased as well as when a second target station is constructed at the MLF, a beam power of 1.5 MW has to be realized in the RCS. However, the simulation shows that beyond 1 MW the beam is unstable even if no chromaticity is corrected. A reduction of the kicker impedance by at least a half is required in order to achieve 1.5 MW beam power in the RCS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB025

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB029

Simulation of the Single Bunch Instabilities for the High Energy Photon Source

injection, simulation, operation, photon

3760

Z. Duan, N. Wang, H.S. Xu
IHEP, Beijing, People's Republic of China

Funding: Work supported by Natural Science Foundation of China (No.11605212).
Timing modes pursing a large single bunch charge will be important operation modes for the green-field High Energy Photon Source (HEPS). The single bunch instabilities are simulated with the elegant tracking code, based on the current impedance budget. In particular, a novel on-axis accumulation scheme* based on the RF gymnastics of an active double-RF system was proposed as a candidate injection scheme for HEPS, while the zero-current rms bunch length dramatically decreases during the injection, from 32 mm to 3 mm, over a time duration of about 200 ms. The single bunch instabilities are evaluated for both the operation mode with optimal bunch lengthening as well as the injection mode with the very short bunch length, as a first step in understanding the possible beam instability for this injection scheme.
* G. Xu, et al., in Proc. IPAC'16, pp. 2886-2888. Z. Duan, et al., in Proc. eeFACT 2016.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB029

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB030

Studies on Collective Instabilities in HEPS

injection, operation, ion, damping

3763

N. Wang, Z. Duan, C. Li, S.K. Tian, H.S. Xu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a new designed photon source at beam energy of 6 GeV. Due to the small beam size and increased coupling impedance with the restricted beam pipe aperture, the collective effects may bring new challenges to the physical design of the machine. The collective instabilities are estimated for different operation mode. The critical instability issues are also identified for each mode.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB032

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

emittance, coupling, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB057

Method to Calculate the Longitudinal Impedance From a Partial Wakefield Simulation

wakefield, simulation, cavity, factory

3844

N.C. Shipman
UMAN, Manchester, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
R. Calaga
CERN, Geneva, Switzerland
J.A. Mitchell
Lancaster University, Lancaster, United Kingdom

When simulating modes with high Q-factors, the wakefield length necessary to calculate the impedance spectrum can often mean a computation time of several weeks or more. A method has been developed which enables the longitudinal impedance and Q-factors of multiple modes to be calculated from a partially decayed wakefield simulation. This paper presents an overview of the method along with preliminary, proof of principle, results showing that considerable simulation time can be saved whilst maintaining a good degree of accuracy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB057

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB065

A Tool for Small Longitudinal Beam Dynamics in Synchrotrons

synchrotron, simulation, emittance, longitudinal-dynamics

3865

J.-F. Ostiguy, V.A. Lebedev
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
A number of codes are available to simulate longitudinal dynamics in synchrotrons. The most established ones include TIBETAN, LONG1D, ORBIT, and ESME. While they embody a wealth of accumulated wisdom and experience, most of these codes were written decades ago and to some extent they reflect the constraints of their time. As a result, there is interest for updated tools taking better advantage of modern software and hardware capabilities. At Fermilab, the PIP-II project has provided the impetus for development of such a tool. In this contribution, we discuss design decisions and code architecture. A selection of test cases based on an initial prototype are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB065

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB080

Estimations of Coherent Instabilities for JLEIC

electron, ion, proton, collider

3903

R. Li
JLab, Newport News, Virginia, USA

Funding: Work supported by the Department of Energy, Laboratory Directed Research and Development Funding, under Contract No. DE-AC05-06OR23177
JLEIC is the medium energy electron-ion collider currently under active design at Jefferson Lab*. The design goals of JLEIC are both high luminosity (1033-1034 cm^-2ses⁻¹) and high polarization (>70%) for the electron and light ion beams, for a wide range of electron and ion beam energies and for a wide spectrum of ion species. The unprecedented luminosity goal for this electron-ion collider sets strong requirements for the understanding and management of potential collective effects in JLEIC. In this paper, we present preliminary estimations of single and coupled bunch coherent instabilities for the electron and proton beams at collision energies for the JLEIC design. Further improvement of the estimations and mitigation methods are discussed.
* MEIC design summary, http://arxiv.org/ftp/arxiv/papers/1504/1504.07961.pdf, (2015).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB080

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB111

Sub-Femtosecond Jitter Ultra High Performance Oscillators for Accelerator Timing

controls, coupling, cavity, electron

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB111

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB115

Development of a Longitudinal Feedback System for Coupled Bunch Instabilities Caused by the Accelerating Mode at Superkekb

cavity, operation, damping, target

3989

K. Hirosawa, K. Akai, E. Ezura, T. Kobayashi, K. Nakanishi, M. Nishiwaki, S.I. Yoshimoto
KEK, Ibaraki, Japan

SuperKEKB is an asymmetric energy electron-positron circular collider. Phase-I commissioning was operated from February to June in 2016. The purpose of this accelerator is to aim at the higher luminosity than KEKB, so a larger beam current is made for it. In the future plan, beam currents in the electron and positron rings will be increased to 2.6A and 3.6A, respectively. As we consider beam dynamics in the storage ring, higher mode instability associated with the accelerating mode will be caused by a large beam current. Especially the target instability of this study is called μ=-2 mode Coupled Bunch Instability. To suppress it, we developed new feedback components for longitudinal coupled bunch instability. We have same mechanism feedback components for KEKB, but it supports only μ=-1 mode instability. Since a large current makes μ=-1 mode instability big, there is a possibility that suppression is difficult only by using KEKB components. In order to deal with this problem, new components we developed support μ=-1, -2, and -3 mode instabilities, and we improved the performance and usability as compared to existing components. We schedule studies using a beam at Phase-II.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB115

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK002

Development of a Range of High Peak Power Solid-State Amplifiers for Use in the Heavy Ion Linac at JINR, Dubna

cavity, ion, linac, heavy-ion

4108

S.C. Dillon, J.L. Reid
Tomco Technologies, Stepney, South Australia, Australia
A.V. Butenko
JINR, Dubna, Moscow Region, Russia
H. Höltermann, H. Podlech, U. Ratzinger
BEVATECH, Frankfurt, Germany

A range of LDMOS based amplifiers rated for up to 340kW peak power and operating at 100.625MHz were developed for use as RF sources for driving cavities in the heavy ion LINAC (HILac) at JINR, Dubna. The final solution had to be compact and competitive while addressing technical challenges such as phase and amplitude stability, long term reliability, reflected power handling and serviceability. Design considerations and performance results are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK002

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK014

Travelling Wave Accelerating Structure for Areal 50 MeV Energy Upgrade

cavity, simulation, electron, gun

4130

A. Vardanyan, V. Danielyan, S.G. Dekhtiarov, B. Grigoryan, L. Hakobyan, T. Markosyan, A.S. Simonyan
CANDLE SRI, Yerevan, Armenia
W. Ackermann
TEMF, TU Darmstadt, Darmstadt, Germany
A.V. Tsakanian
HZB, Berlin, Germany

AREAL facility development implies energy upgrade to 50 MeV in order to drive a THz free electron laser. To reach this goal, the installation of two 1.6 m long S-Band travelling wave accelerating sections, with nominal accel-erating gradient of 15 MV/m, are foreseen. In this paper the design study of accelerating sections along with the matching performance of RF couplers are presented. The simulations are performed using the CST Microwave Studio. The first results of the accelerating structure proto-type fabrication are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK014

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK015

Prototype Results of the ESR Barrier-Bucket System

cavity, accumulation, coupling, 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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK043

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

coupling, 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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK045

Design of a C-band Travelling-wave Accelerating Structure at IHEP

cavity, linac, simulation, wakefield

4196

J.R. Zhang, Y.L. Chi, J. Lei, H. Wang, X. Wang
IHEP, Beijing, People's Republic of China
S. Shu
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

A C-band travelling wave accelerating structure has been developed at IHEP. The structure is a constant gra-dient type and operating with a 3'/4 mode. The total length of the structure is 1.8-meters long with 85 regular cells and two coupler cells. 2D program Superfish is used to optimize the cavity shape and the iris size. The wall cells are rounded for it can improved the Q value for about 10%. The cell irises have an elliptical profile to minimize the peak surface electric fields. In order to compatible with the compact of the short-range wake field on the beam dynamics, the average iris radius is 7.15 mm. The group velocity of the designed structure is from 2.8% to 1.4%. Between the rectangular waveguide and the accelerating structure, magnetic coupling is adopted. The coupled cavity is racetrack type in order to minimize the asymmetry in the coupler. Kyhl's method is used to match the input and output coupler.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK060

Tuning of an S-Band 10 MeV Traveling-Wave Accelerating Structure with a Non-uniform Section

network, electron, cavity, collider

4233

J.H. Shao, H.B. Chen, C. Gong, J. Shi, X.W. Wu, S.X. Zheng
TUB, Beijing, People's Republic of China

A tuning method of nonuniform travelling wave structures has been developed based on non-resonant perturbation measurement at Tsinghua University. The filed distribution is normalized with the shunt impedance and attenuation of each cell. Then their internal reflection can be deduced and corrected by cavity deforming. This method has been applied to an S-band 10 MeV travelling wave structure successfully. In this paper, the detailed tuning method and cold test results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK060

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK068

High Power Test of SINAP X-Band Deflector at KEK

cavity, electron, operation, laser

4251

J.H. Tan, W. Fang, Q. Gu, X.X. Huang, Z.B. Li, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
T. Higo
KEK, Ibaraki, Japan
D.C. Tong
TUB, Beijing, People's Republic of China

A crucial RF structure used for bunch length measurement for Shanghai X-ray Free Electron Lasers (SXFEL) at the Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Science [1]. The design, fabrication, measurement and tuning have been completed at SINAP [2], and the high power test was carried out at Nextef of KEK with international collaboration. This paper presents the RF conditioning process and test results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK068

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK078

1.5 GHz Cavity Design for the CLIC Damping Ring and as Active Third Harmonic Cavity for ALBA

cavity, HOM, damping, simulation

4263

B. Bravo, J.M. Alvarez, F. Pérez, A. Salom
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

In a collaboration framework between CERN and ALBA, we are designing a normal conducting active 1.5 GHz cavity which could serve as main RF system for the Damping Ring of CLIC and as an active third harmonic cavity for the ALBA Storage Ring. The third harmonic cavity at ALBA will be used to increase the bunch length in order to improve the beam lifetime and increase the beam stability thresholds. The main advantage of an active third harmonic cavity is that optimum conditions can be reached for any beam current. This paper presents the preliminary design of this cavity: an active, normal conducting cavity tuned at 1.5 GHz based on the 500 MHz European Higher Order Mode (HOM) damped normal conducting with nose cones using ridged circular waveguides for HOM damping. Electromagnetic simulations, mechanical and thermal stress analysis will be presented together with the calculations on beam stability improvement due to the third harmonic system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK078

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK086

Design and Implementation of Stripline Feedback Kickers in the MAX IV 3 GeV Ring

feedback, kicker, storage-ring, cavity

4285

D. Olsson, L. Malmgren, K. Åhnberg
MAX IV Laboratory, Lund University, Lund, Sweden

The commissioning of a bunch-by-bunch feedback system for the MAX IV 3 GeV storage ring was started in early 2016. At date, the actuators are two stripline kickers oriented in the horizontal and in the vertical plane, respectively. Apart from providing feedback in the transverse plane, the horizontal stripline is simultaneously operating as a longitudinal kicker. This is done by upconverting the longitudinal 0 - 50 MHz baseband signal to the 150 MHz - 250 MHz range where the longitudinal shunt impedance of the stripline is higher. This signal is then fed to the stripline electrodes in common-mode. The design of the stripline kickers and the layout of the bunch-by bunch feedback system in the 3 GeV ring are presented in this report. Results from instability studies in this ring are also discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK086

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK087

A Waveguide Overloaded Cavity Kicker for the MAX IV Bunch-by-Bunch Feedback System

cavity, feedback, kicker, storage-ring

4289

D. Olsson, L. Malmgren, K. Åhnberg
MAX IV Laboratory, Lund University, Lund, Sweden

The higher-order modes (HOMs) in the main and the 3:rd harmonic cavities are driving longitudinal coupled-bunch mode instabilities (CBMIs) in the MAX IV 3 GeV storage ring. This far, negative feedback has been applied in the longitudinal plane by a stripline kicker at lower ring currents. However, the maximum longitudinal feedback voltage provided by the stripline is rather weak, and a waveguide overload cavity was therefore designed in order to suppress CBMIs at higher ring currents as well. Due to the long bunch length in the MAX IV storage rings, a relatively low center frequency of 625 MHz is selected. The new cavity kicker has been manufactured, and will be installed in the 3 GeV ring during the summer shut-down of 2017. In this paper, the RF and mechanical design of the cavity is presented. Simulation results are also compared with measurements of the manufactured cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK087

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK088

A Compact 10 kW Solid-State RF Power Amplifier at 352 MHz

operation, insertion, network, linac

4292

D.S. Dancila, A. Rydberg
Uppsala University, Department of Engineering Sciences, Uppsala, Sweden
A.E.T. Hjort, L. Hoang Duc, M.H. Holmberg, M. Jobs, R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden

A compact 10 kW RF power amplifier at 352 MHz was developed at FREIA for the European Spallation Source, ESS. The specifications of ESS for the conception of amplifiers are related to its pulsed operation: 3.5 ms pulse length and a duty cycle of 5\%. The realized amplifier is composed of eight kilowatt level modules, combined using a planar Gysel 8-way combiner. The combiner has a low insertion loss of only 0.2 dB, measured at 10 kW peak power. Each module is built around a commercially available LDMOS transistor in a single-ended architecture. During the final measurements, a total output peak power of 10.5 kW was measured.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK088

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK110

RF Cavity Design for a Low Cost 1 MeV Proton Source

cavity, proton, simulation, acceleration

4355

D. Soriano Guillén, R. Seviour
University of Huddersfield, Huddersfield, United Kingdom
S. Hunt
Alceli Accelerator Technology Ltd., Huddersfield, United Kingdom

In this paper we present the design for a low-cost RF cavity capable of accelerating protons from 100 keV to 1 MeV. The system is designed to meet the specifications from the proposed Alceli LTD medical proton therapy linac, to deliver a 1 nA proton beam current with a 1 kHz repetition rate. We present a design of an RF normal conducting (NC) re-entrant Cu cavity operating at 40 MHz consisting of a coupled two cavity system, both driven by a single Marx generator. The choice of such a low operating frequency for the cavity system enables us to use a relatively low-cost cost Marx Generator as the RF source. Marx generators work in a similar fashion to a Cockcroft-Walton accelerator (without the expensive components), creating a high-voltage pulse by charging a number of capacitors relatively slowly in parallel, then rapidly discharging in series, via spark gaps. Marx generators can deliver 2.5 GW, 1 ns pulses, with rise times of 200 ps, and (relatively) low jitter.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK110

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPIK117

High Efficiency High Power Resonant Cavity Amplifier for Accelerator Applications

cavity, operation, coupling, 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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA012

Transverse Impedance Measurement in SuperKEKB

damping, betatron, operation, storage-ring

4442

N. Kuroo
UTTAC, Tsukuba, Ibaraki, Japan
T. Ishibashi, T. Mimashi, K. Ohmi, Y. Ohnishi, K. Shibata, Y. Suetsugu, S. Terui, M. Tobiyama, D. Zhou
KEK, Ibaraki, Japan

In KEK(Japan), SuperKEKB project is progressing toward upgrade. This project aims improvement luminosity (8×10³⁵ cm^-2s- 1) which is 40 times of the performance of the KEKB accelerator. In Phase 1 of this project, a performance test as storage ring was carried out. Understanding of ring Impedance/wake is an important subject in phase I. Measurement of Head Tail Damping using Turn by Turn monitor was performed to evaluate impedance/wake. Betatron motion is excited by kicker and its damping is measured for several parameters sets of bunch current and chromaticity in both HER and LER. The wake field was calculated from the decrement of betatron amplitude. We present the wake field which is cross-checked with tune shift based on the current dependence.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA022

Comparison of Different Methods to Calculate Induced Voltage in Longitudinal Beam Dynamics Codes

simulation, wakefield, dipole, damping

4465

D. Quartullo, J. Repond
CERN, Geneva, Switzerland
M. Migliorati
University of Rome La Sapienza, Rome, Italy

Collective effects in longitudinal beam dynamics simulations are essential for many studies since they can perturb the RF potential, giving rise to instabilities. The beam induced voltage can be computed in frequency or time domain using a slicing of the beam profile. This technique is adopted by many codes including CERN BLonD. The slicing acts as a frequency filter and cuts high frequency noise but also physical contributions if the resolution is not sufficient. Moreover, a linear interpolation usually defines the voltage for all the macro-particles, and this can be another source of unphysical effects. The MuSiC code describes interaction between the macro-particles with the wakes generated only by resonator impedances. The complications related to the slices are avoided, but the voltage can contain high frequency noise. In addition, since the computational time scales with the number of resonators and macro-particles, having a large number of them can be cumbersome. In this paper the features of the different approaches are described together with benchmarks between them and analytical formulas, considering both single and multi-turn wakes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA023

Studies of Longitudinal Beam Stability in CERN PS Booster After Upgrade

simulation, space-charge, emittance, injection

4469

D. Quartullo, S.C.P. Albright, E.N. Shaposhnikova
CERN, Geneva, Switzerland

The CERN PS Booster, comprised of four superposed rings, is the first synchrotron in the LHC proton injection chain. In 2021, after major upgrades, the injection and extraction beam energies, as well as the acceleration rate, will be increased. The required beam intensities should be a factor of two higher for nominal LHC and fixed-target beams, and the currently used narrow-band ferrite systems will be replaced by broad-band Finemet cavities in all four rings. Future beam stability was investigated using simulations with the Beam Longitudinal Dynamics (BLonD) code. The simulation results for existing situation were compared with beam measurements and gave a good agreement. An accurate impedance model, together with a careful estimation of the longitudinal space charge, was used in simulations of the future acceleration cycle in single and double RF, with phase and radial loops and controlled longitudinal emittance blow-up. Since the beam is not ultra-relativistic and fills the whole ring (h=1), the front and multi-turn back wakes were taken into account, as well as the RF feedbacks which reduce the effect of the Finemet impedance at the revolution frequency harmonics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA023

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA024

Controlled Longitudinal Emittance Blow-Up Using Band-Limited Phase Noise in CERN PSB

emittance, simulation, synchrotron, injection

4473

D. Quartullo, E.N. Shaposhnikova, H. Timko
CERN, Geneva, Switzerland

Controlled longitudinal emittance blow-up (from 1 eVs to 1.4 eVs) for LHC beams in the CERN PS Booster is currently achievied using sinusoidal phase modulation of a dedicated high-harmonic RF system. In 2021, after the LHC injectors upgrade, 3 eVs should be extracted to the PS. Even if the current method may satisfy the new requirements, it relies on low-power level RF improvements. In this paper another method of blow-up was considered, that is the injection of band-limited phase noise in the main RF system (h=1), never tried in PSB but already used in CERN SPS and LHC, under different conditions (longer cycles). This technique, which lowers the peak line density and therefore the impact of intensity effects in the PSB and the PS, can also be complementary to the present method. The longitudinal space charge, dominant in the PSB, causes significant synchrotron frequency shifts with intensity, and its effect should be taken into account. Another complication arises from the interaction of the phase loop with the injected noise, since both act on the RF phase. All these elements were studied in simulations of the PSB cycle with the BLonD code, and the required blow-up was achieved.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA024

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA026

Practical Stabilisation of Transverse Collective Instabilities with Second Order Chromaticity in the LHC

simulation, octupole, damping, sextupole

4477

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

The study reports on dedicated measurements made with a single nominal bunch in the LHC at 6.5 TeV. First, we show that a significant amount of second order chromaticity Q'' can be introduced in the machine in a well-controlled manner. Second, we demonstrate that the incoherent betatron tune spread from Q'' can provide beam stability through the Landau damping mechanism. This is a first step in the development of a Q'' knob to be potentially applied during regular physics operation in the LHC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA026

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA028

Multi-Bunch Instabilities Measurement and Analysis at the Diamond Light Source

damping, vacuum, insertion-device, insertion

4485

R. Bartolini, R.T. Fielder, E. Koukovini-Platia, G. Rehm
DLS, Oxfordshire, United Kingdom

The characterisation of the multi-bunch dynamics at the Diamond light source is performed with an advanced TMBF system that is capable of operating fast grow damp experiments thus allowing the exploration of many machine conditions. We report here the latest results of the measurement campaign, the implication on the machine impedance model and some of the intricacies of the analysis and interpretation of the experimental data.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA028

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA030

Collective Effects Studies of the Double-Double Bend Achromat Cell at Diamond

simulation, storage-ring, dipole, insertion-device

4493

E. Koukovini-Platia, R. Bartolini, L.M. Bobb, R.T. Fielder
DLS, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom

One cell of the Diamond storage ring has been converted from a double bend achromat to a double-double bend achromat (DDBA). After the successful installation and beam commissioning in November 2016, beam-based studies were done to assess the effect of the new cell on the single bunch and multi-bunch instabilities both in transverse and longitudinal planes. These are compared with the impedance estimate carried out both numerically and analytically.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA073

Latest Results on Fast Kicker for g-2 E-989 Experiment at Fermilab

kicker, experiment, storage-ring, injection

4616

A.A. Mikhailichenko, D. L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

We are describing the latest results on fabrication and measurements of kicker and pulser and beam dynamics in E-989 experiment at FERMILAB on precise measurement of anomalous magnetic moment of muon.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA073

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA084

Evaluation of Collective Effects in Iranian Light Source Facility (ILSF) Storage Ring

storage-ring, vacuum, emittance, scattering

4650

E. Ahmadi, S. Ahmadiannamin, J. Rahighi
ILSF, Tehran, Iran
S.M. Jazayeri
IUST, Narmac, Tehran, Iran

In this paper, we present the calculations of various collective effects in the storage ring of ILSF, a synchrotron light source under design in Iran. The ILSF storage ring is based on 5-BA lattice structure and emittance of 270 pm-rad which is optimized to provide high brightness and flux photons for the users. Because of design features, small radius vacuum pipe and small momentum compaction factor of lattice, it is expected that instabilities emerging from collective effects will affect significantly the beam quality and make it is challenging to reach maximum designed beam current. We will address the results of beam quality degradation and threshold calculations for different singlebunch and multibunch instabilities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA084

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA085

Design and Construction of 126 MHz Capacity Loaded Aluminium Cavity Prototype

cavity, simulation, higher-order-mode, pick-up

4653

S. Ahmadiannamin, J. Rahighi, Kh.S. Sarhadi
ILSF, Tehran, Iran
F. Abbasi
Shahid Beheshti University, Tehran, Iran
M. Lamehi Rashti
IPM, Tehran, Iran

Iranian light source Facility (ILSF)isa 3 GeV Ultra low emittance synchrotron with 528 meter circumference that will be constructed in the city of Qazvin, located 150km west of Tehran. Motivated by the development of HOM damped cavity with simpler structure at 100 MHz at MAX Lab and also lower costs, 100 MHz RF system is envisaged for ILSF booster and storage ring. An RF cavity prototype was fabricated for better understandingof characteristics of capacity loaded RF cavities by practical investigation. In this paper, design and development of this prototype is presentedwith the simulation and measurement results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA085

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA105

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

cavity, coupling, electron, 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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA146

Robust Linac Platform for Wide Replacement of Radioactive Sources

vacuum, linac, simulation, coupling

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

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

FRXAB1

Accelerator Vacuum Technology Challenges for Next-Generation Synchrotron-Light Sources

vacuum, photon, storage-ring, lattice

4830

P. He
IHEP, Beijing, People's Republic of China

The development trend of future next-generation synchrotron light source storage rings is a compact lattice combined with small magnet apertures. This leads to important engineering challenges for the design and performance of a vacuum system because of lack of space, conductance limitation and high precision and stability positioning requirements. The speaker will review some possible solutions including the use of distributed pumping (NEG coating), distributed absorber (good thermal conducting material vacuum chamber wall), and distributed cooling (different water cooling channel design at the location where the synchrotron radiation hits the wall). In situ baking for NEG activation and precise installation will also be covered.

Slides FRXAB1 [3.627 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-FRXAB1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)