IPAC2016 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOZA01	Simulated Beam-beam Limits for Circular Lepton and Hadron Colliders	collider, luminosity, lepton, hadron	27
	K. Ohmi KEK, Ibaraki, Japan
	The beam-beam limit is one of the most important collider parameters. For lepton colliders the empirical tune shift limits are higher than for hadron colliders, which has been attributed to strong radiation damping. The beam-beam limit in hadron colliders, like the LHC, can be affected by noise. For future higher-energy colliders, like FCC-hh or SppC, the limit can be higher or lower, in the presence of still rather weak synchrotron radiation. For circular lepton colliders, like DAΦNE, SuperKEKB, FCC-ee or CepC, the effect of large Piwinski angle, and crab waist, as well as the dependence of the beam-beam limit on the number of interaction points are important questions. This presentation reviews the state of the art in weak-strong, quasi-strong-strong and strong-strong beam-beam simulations and reports the various dependencies of the simulated beam-beam limit on the aforementioned parameters.
	Slides MOZA01 [4.453 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOZA01
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MOOCB01	PACMAN Project: A New Solution for the High-accuracy Alignment of Accelerator Components	alignment, quadrupole, target, collider	58
	H. Mainaud Durand, K. Artoos, M.C.L. Buzio, D. Caiazza, N. Catalán Lasheras, A. Cherif, I.P. Doytchinov, J.-F. Fuchs, A. Gaddi, N. Galindo Munoz, J. Gayde, S.W. Kamugasa, M. Modena, P. Novotny, S. Russenschuck, C. Sanz, G. Severino, D. Tshilumba, V. Vlachakis, M. Wendt, S. Zorzetti CERN, Geneva, Switzerland
	The beam alignment requirements for the next generation of lepton colliders have become increasingly challenging. As an example, the alignment requirements for the three major collider components of the CLIC linear collider are as follows. Before the first beam circulates, the Beam Position Monitors (BPM), Accelerating Structures (AS)and quadrupoles will have to be aligned up to 10 μm w.r.t. a straight line over 200 m long segments, along the 20 km of linacs. PACMAN is a study on Particle Accelerator Components' Metrology and Alignment to the Nanometre scale. It is an Innovative Doctoral Program, funded by the EU and hosted by CERN, providing high quality training to 10 Early Stage Researchers working towards a PhD thesis. The technical aim of the project is to improve the alignment accuracy of the CLIC components by developing new methods and tools addressing several steps of alignment simultaneously, to gain time and accuracy. The tools and methods developed will be validated on a test bench. This paper presents the technical systems to be integrated in the test bench, the results of the compatibility tests performed between these systems, as well as the final design of the PACMAN validation bench.
	Slides MOOCB01 [9.553 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOOCB01
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MOOCB02	A Lattice Correction Approach through Betatron Phase Advance	lattice, sextupole, dynamic-aperture, betatron	62
	W. Guo, S.L. Kramer, F.J. Willeke, X. Yang, L. Yu 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 Most lattice correction algorithms, such as LOCO, rely on the amplitude of the BPM signals. However, these signals are a mixture of the BPM gain and beta-beat. Even though BPM gain can be fitted by analyzing the statistics of all the BPMs in a ring accelerator, we found the uncertainty is on the order of a few percent. On the other hand, the betatron phase advance, which is obtained from the correlation of two adjacent BPMs, is independent of the BPM gain and tilt error. It was found at NSLS-II that the measurement precision of the phase advance is typically 0.001 radian, which corresponds to about 0.2% of beta beat. The phase error can be corrected similarly using a response matrix, and at NSLS-II the phase error can be corrected to <0.005 radian (p-p) in less than half an hour. The same technique can be applied to the nonlinear lattice. By comparing the phase advance differences between the on- and off- orbit lattices, the sextupole strength error can be identified. Simulation and experimental results will be demonstrated in the paper.
	Slides MOOCB02 [1.554 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOOCB02
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MOPMB003	Comparison of Coherent Smith-Purcell Radiation and Coherent Transition Radiation	radiation, electron, laser, free-electron-laser	72
	V. Khodnevych, N. Delerue LAL, Orsay, France O.A. Bezshyyko, V. Khodnevych National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine
	Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01) and the IDEATE International Associated Laboratory (LIA) between France and Ukraine. Smith-Purcell radiation and Transition Radiation are two radiative phenomenon that occur in charged particles accelerators. For both the emission can be significantly enhanced with sufficiently short pulses and both can be used to measure the form factor of the pulse. We compare the yield of these phenomenon in different configurations and look at their application as bunch length monitors, including background filtering and rejection. We apply these calculations to the specific case of the CLIO Free Electron laser.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB003
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MOPMB004	Comparison of the Smith-purcell Radiation Yield for Different Models	radiation, electron, experiment, detector	75
	M.S. Malovytsia, N. Delerue LAL, Orsay, France M.S. Malovytsia KhNU, Kharkov, Ukraine
	Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01) and the IDEATE International Associated Laboratory (LIA) France-Ukraine. Smith-Purcell radiation is used in several applications including the measurement of the longitudinal profile of electron bunches. A correct reconstruction of such profile requires a good understanding of the underlying model. We have compared the leading models of Smith-Purcell radiation and shown that they are in agreement within the experimental errors.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB004
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MOPMB005	Study of Short Bunches at the Free Electron Laser CLIO	radiation, cavity, electron, gun	78
	V. Khodnevych, N. Delerue, S. Jenzer LAL, Orsay, France J.P. Berthet, F. Glotin, J.-M. Ortega, R. Prazeres CLIO/ELISE/LCP, Orsay, France V. Khodnevych National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine
	Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01). CLIO is a Free Electron Laser based on a thermionic electron gun. In its normal operating mode it delivers electron 8 pulses but studies are ongoing to shorten the pulses to about 1 ps. We report on simulations showing how the pulse can be shortened and the expected signal yield from several bunch length diagnostics (Coherent Transition Radiation, Coherent Smith Purcell Radiation).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB005
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MOPMB006	First Tests of SuperKEKB Luminosity Monitors during 2016 Single Beam Commissioning	luminosity, vacuum, scattering, background	81
	D. El Khechen, P. Bambade, A. Blin, P. Cornebise, D. Jehanno, V. Kubytskyi, Y. Peinaud, C. Rimbault LAL, Orsay, France Y. Funakoshi, Y. Ohnishi, S. Uehara KEK, Ibaraki, Japan
	The SuperKEKB e⁺e⁻ collider aims to reach a very high luminosity of 8 10³⁵ cm^-2s⁻¹, using highly focused ultra-low emittance bunches colliding every 4ns. Fast luminosity monitoring is required for luminosity feedback and optimisation in presence of dynamic imperfections. The aimed relative precision is about 10^-3 in 1ms, which can be in principle achieved thanks to the very large cross-section of the radiative Bhabha process at zero degree scattering angle. Diamond, Cherenkov and scintillator sensors are to be placed just outside the beam pipe, downstream of the interaction point in both rings, at locations with event rates consistent with the aimed precision and small enough backgrounds from single-beam particle losses. The initial configuration installed for the 2016 "phase 1" single beam commissioning will be described, including the sensors, mechanical setup, readout electronics and first stage DAQ. Preliminary measurements and analysis of beam gas Bremsstrahlung loss data collected with the luminosity monitors will be reported and compared with a detailed simulation, for several experimental conditions during the SuperKEKB commissioning.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB006
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MOPMB007	Diamond Sensor Resolution in Simultaneous Detection of 1,2,3 Electrons at the PHIL Photoinjector Facility at LAL	electron, detector, experiment, target	84
	V. Kubytskyi, P. Bambade, S. Barsuk LAL, Orsay, France O.A. Bezshyyko, V. Krylov, V. Rodin National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine
	In this paper, we present experimental and numerical studies of the signals from the Poisson-like distributions resulting from electrons incident on a diamond sensor placed near the exit of the PHIL photoinjector facility at LAL. The experiments were performed at the newly commissioned Low Energy Electron TECHnology (LEETECH) platform at PHIL. Bunches of 10x9 electrons are first generated and accelerated to 3.5 MeV by PHIL. The electrons are then filtered in LEETECH by a system of collimators, using a dipole magnet for momentum selection. The diamond sensor is located immediately after the output collimator to collect electrons in the range 2.5-3 MeV. We show that with standard scCVD diamonds of 500 micrometers thickness, the energy losses from the first three MIP (minimum ionizing particle) electrons are clearly resolved. We did not observe distinguishable peaks in cases when a significant fraction of the incident electrons had energies below a MIP. The described technique can be used as complementary approach for calibration of diamond detectors as well as to diagnose and help control accelerated beams in a regime down to a few particles.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB007
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MOPMB009	Electron Beam Probe for the Bunch Length Measurements at BERLinPro	electron, diagnostics, gun, operation	92
	D. Malyutin, A.N. Matveenko HZB, Berlin, Germany
	For the successful operation of various accelerator facilities a detailed bunch characterization is required. A complete description can be achieved using various diagnostic systems installed along an accelerator beamline. Ideally the diagnostic should be able to measure parameters of a single bunch in a non-destructive manner. For bunch length measurements this results in a complicated task especially for bunch duration below 1 ps. One of the possible solutions is a diagnostic based on the interaction of a low energy electron beam with electro-magnetic fields of the relativistic bunch. The bunch length can be readily deduced from the resulting scatter. In this paper bunch length measurement technique based on a low energy electron beam is introduced. Results of numerical simulations of measurements are presented. A possible setup of such diagnostic system for BERLinPro facility is proposed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB009
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MOPMB013	Time-resolved Spectral Observation of Coherent THz Pulses at DELTA	radiation, laser, electron, detector	105
	C. Mai, F.H. Bahnsen, M. Bolsinger, F. Götz, S. Hilbrich, M. Höner, M.A. Jebramcik, S. Khan, N.M. Lockmann, A. Meyer auf der Heide, R. Molo, R. Niemczyk, G. Shayeganrad, M. Suski, P. Ungelenk, D. Zimmermann DELTA, Dortmund, Germany
	Funding: Work supported by the BMBF (05K13PEC), the DFG (INST 212/236-1) and the state of NRW. Coherent THz pulses induced by a laser-electron interac- tion are routinely produced and observed at DELTA, a 1.5- GeV synchrotron light source operated by the TU Dortmund University. At a dedicated THz beamline, measurements using a Fourier-transform spectrometer have been performed between 1 THz and 7 THz. Recently, an ultrafast Schottky- diode detector and a novel polarizing Fourier-transform spec- trometer were installed, which enable turn-by-turn-resolved spectral measurements in the frequency range below 1 THz. The commissioning results of the new spectrometer and simulations are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB013
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MOPMB017	Design Issues for the Optical Transition Radiation Screens for theELI-NP Compton Gamma Source	radiation, electron, linac, laser	118
	M. Marongiu, A. Giribono, A. Mostacci, V. Pettinacci INFN-Roma, Roma, Italy D. Alesini, E. Chiadroni, F. Cioeta, G. Di Pirro, V.L. Lollo, L. Pellegrino, V. Shpakov, A. Stella, C. Vaccarezza, A. Variola INFN/LNF, Frascati (Roma), Italy A. Cianchi INFN-Roma II, Roma, Italy L. Palumbo University of Rome La Sapienza, Rome, Italy
	A high brightness electron LINAC is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32, 16 ns spaced, bunches with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation profile monitors. In order to measure the beam properties along the train, the screens must sustain the thermal stress due to the energy deposited by the bunches; moreover the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the analytical studies as well as numerical simulations to investigate the thermal behaviour of the screens impinged by the nominal bunch; the design and the performance of the optical detection line is discussed as well.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB017
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MOPMB018	Metrological Characterization of the Bunch Length Measurement by Means of a RF Deflector at the ELI-NP Compton Gamma source	linac, electron, laser, brightness	122
	L. Sabato U. Sannio, Benevento, Italy D. Alesini, C. Vaccarezza, A. Variola INFN/LNF, Frascati (Roma), Italy P. Arpaia CERN, Geneva, Switzerland P. Arpaia, A. Liccardo Naples University Federico II, Science and Technology Pole, Napoli, Italy A. Giribono University of Rome La Sapienza, Rome, Italy A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy L. Sabato INFN-Napoli, Napoli, Italy
	Bunch length measurement in linac can be carried out using a RF deflector, which provides a transverse kick to the beam. The transverse beam size on a screen, placed after the RF deflector, represents the bunch length. In this paper, the metrological characterization of the bunch length measurement technique is proposed. The uncertainty and the systematic errors are estimated by means of a sensitivity analysis to the measurement parameters. The proposed approach has been validated through simulation by means of ELEGANT code on the parameters interesting for the electron linac of the Compton source at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB018
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MOPMB027	Beam Parameter Measurement After Relocation of S-Band Linear Accelerator	electron, linac, gun, laser	146
	I. Nozawa, M. Gohdo, K. Kan, T. Kondoh, J. Yang, Y. Yoshida ISIR, Osaka, Japan
	Ultrashort electron bunches have been applied in many scientific fields including accelerator physics and radiation chemistry. Pulse radiolysis is application in radiation chemistry, which is a pump-probe measurement using an electron bunch and a laser pulse. Our laboratory aims to generate the electron bunches with durations of less-than femtoseconds using an S-band linear accelerator (linac) at Osaka University in order to improve the time resolution of the pulse radiolysis system. Recently, the linac system was relocated for expanding application using ultrashort electron bunches. The parameters of generated electron bunches including the bunch lengths will be reported.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB027
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MOPMB033	The Influence of Strip-line BPMs' Measuring Results Made by Edge of the Ultra-relativistic Electron Beam	electron, wakefield, positron, linac	161
	S.Z. Wang, N. Gan, X. Huang IHEP, Beijing, People's Republic of China
	This paper describes the impact on the measuring results of the stripline beam position monitor (BPM) produced by the edge of the ultra-relativistic electron beam when we take the transverse size of the beam into account. Simulations have been made by using the Wakefield Solver of CST Particle Studio. And the result of this influence at different ratio of beam horizontal width σ and the BPM inner diameter a has been obtained. This kind of influence has been observed in the stripline BPMs in the transfer line of Beijing Positron Electron Colliders upgraded version II (BEPCII). The research is useful when we design the inner diameter of the stripline BPMs for ultra-relativistic electron beam, meanwhile it provides reference to distinguish the invalid ones from the measuring results obtained by the stripline BPMs in the ultra-relativistic situation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB033
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MOPMB037	Beam Position Monitor Design for Dielectric Wakefield Accelerator In THz Range	wakefield, dipole, polarization, controls	171
	Q. Gao, H.B. Chen, J. Shi TUB, Beijing, People's Republic of China W. Gai ANL, Argonne, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA
	Dielectric based collinear wakefield accelerator have been broadly selected for the THz accelerator due to its simplicity. In order to move the THz accelerators from the current exploratory research into the practical phase, certain common accelerator components are indispensable. Beam Position Monitor (BPM) is one of them. However, most of conventional BPM techniques are hardly scaled down to THz regime. Here we propose a BPM design which uses the dominant dipole mode excited in the dielectric wakefield accelerators to extract information of the beam position.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB037
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MOPMB038	Development of Shoebox BPM for Xi‘an Proton Application Facility	coupling, proton, impedance, closed-orbit	175
	W. Wang, X. Guan, W.-H. Huang, X.W. Wang, Z. Yang, H.Y. Zhang, S.X. Zheng TUB, Beijing, People's Republic of China M.T. Qiu, Z.M. Wang State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Shannxi, People's Republic of China
	In this paper, development of the Shoebox BPM is presented which can be applied for the measurement of turn-by-turn position data, closed orbit and tune of Xi'an Proton Application Facility (XiPAF). The preliminary design of the physical dimensions including the electrode aperture, the pipe aperture and the gap between the two electrodes is performed by calculating their effects on BPM response respectively with the equivalent circuit model. Furthermore, the mechanical structure of the Shoebox BPM is optimized by CST simulation to achieve better performance. The dependency of the BPM sensitivity and zero offset on the frequency is diminished by adding one isolating ring, which decreases coupling capacitance of electrodes and compensates ground capacitance difference of the two electrodes. Finally one prototype of the Shoebox BPM has been fabricated and tested offline. Results show that relative position measurement error due to frequency dependency of sensitivity is less than 1% and absolute measurement error due to frequency dependency of zero offset is expected to be less than 0.1 mm.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB038
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MOPMB042	Design and Simulation of Button Beam Position Monitor for IR-FEL*	vacuum, FEL, electron, electronics	187
	X.Y. Liu, P. Lu, B.G. Sun, L.L. Tang, F.F. Wu, Y.L. Yang, T.Y. Zhou, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: * Supported by the National Science Foundation of China (11575181, 11175173) A new button-type beam position monitor(BPM) was designed for the IR-FEL project. Firstly, the longitudinal size of BPM needs to be short enough to save space because the entire machine of IR-FEL is very compact. And in the matter of installation problem, all four electrodes are deviated 30 degrees from the horizontal axis. Then, according to these two limited conditions and beam parameters, we builded up a simple model and did some simulated calculations to ensure a good performance of position resolution, which should be better than 50μm. The simulations include an estimation of induced signals in both time and frequency domains, horizontal and vertical sensitivities, mapping figures and so on. This button BPM will be manufactured in the near future and then we can do some off-line experiments to test it. # Corresponding author (email: bgsun@ustc.edu.cn)
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB042
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MOPMB046	Design and Calculation Error Analysis of a High Order Mode Cavity Bunch Length Monitor	cavity, positron, linac, electron	196
	J.G. Guo, Q. Luo, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: National Science Foundation of China (11375178) and Fundamental Research Funds for the Central Universities (WK2310000046). A two-cavity bunch length monitor for linac of positron source is designed. Fifth harmonic cavity resonates at 14.28 GHz (fifth harmonic of the linac fundamental frequency 2.856 GHz) with mode TM020, as this mode could provide larger cavity radius. Each cavity equipped with a filter to suppress unwanted signal. An improved bunch length calculation method was proposed. A simulation was conducted in CST Particle Studio for beam current from 100-300 mA, bunch length from 5-10 ps. Bunch length was calculated and compared by these two methods
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB046
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MOPMB049	Beam Experiment of Low Q CBPM Prototype for SXFEL	cavity, HOM, electron, FEL	202
	J. Chen, L.W. Lai, Y.B. Leng, L.Y. Yu, R.X. Yuan SINAP, Shanghai, People's Republic of China
	To meet the high resolution beam position measurement requirement of micron or sub-micron for shanghai soft X-ray free electron laser (SXFEL) under construction, the cavity beam position monitor (CBPM) operating at C-band and the corresponding electronic has been designed by SINAP. In this paper, the design and optimize of the newly low Q cavity BPM is mentioned, the beam test was conducted on the Shanghai Deep ultraviolet free electron laser (SDUV-FEL) facility. CBPM signal processors including broadband oscilloscope and home-made digital BPM processor have been used to evaluate the system performance as well. The beam experimental result, which matched with MAFIA simulation very well, will be presented and discussed in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB049
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MOPMB050	Design of Ultra-wideband Amplifier in RF Front End for Bunch-by-bunch Measurement	power-supply, impedance, experiment, synchrotron-radiation	205
	Y. Yang, Y.B. Leng, Y.B. Yan SSRF, Shanghai, People's Republic of China
	RF front end is one of the key technologies in beam diagnosis, especially in bunch-by-bunch measurement at storage ring. This paper gives the design of ultra-wideband amplifier in RF front end for bunch-by-bunch measurement at SSRF. Simulation have been done to verify the performance of this design.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB050
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MOPMB054	A High Sensitivity Faraday Cup for Ultrashort Electron Bunches	electron, gun, laser, experiment	214
	S. Setiniyaz, I.H. Baek, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, H.W. Kim, S.V. Miginsky, J.H. Nam, S. Park, N. Vinokurov KAERI, Daejon, Republic of Korea S.V. Miginsky, N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	The UED (Ultrafast Electron Diffraction) beamline of KAERI (Korea Atomic Energy Research Institute) WCI (World Class Institute) Center has been successfully commissioned. A S-band co-axial RF photogun with 1.5 cylindrically symmetric cells was used to remove multiple modes of the electric filed inside the cavity. It is designed to generate sub-picosecond electron bunches with energy up to 3.3~MeV. We have developed a system consists of an in-air Faraday cup (FC) and a preamplifier for charge measurement. Tests performed utilizing 3.3~MeV electrons show the system were able to measure ultrashort bunches with tens of femtosecond pulse duration at 10 fC sensitivity. In this paper, we shall present the design, calibration and test results of this system.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB054
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MOPMB058	Bunch Arrival Time Monitor Test at PAL-XFEL ITF	pick-up, LLRF, cavity, resonance	223
	J.H. Hong, J.H. Han, C. Kim, H. Yang PAL, Pohang, Kyungbuk, Republic of Korea
	Femtosecond resolution electron bunch arrival time monitor (BAM) will be required for the beam-based RF phase feedback during PAL-XFEL operation. Two S-band cavity-type BAMs were manufactured for the test at the PAL-XFEL injector test facility (ITF). The resonance frequencies of the cavities are 2856 MHz and 2826.25 MHz. Electron beam induced signal from the cavities was digitized using a low level RF (LLRF) module. In this paper, the resolution of these cavities are analyzed and a possible improvement for better resolution are discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB058
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MOPMR012	Studies of Buffer Gas Cooling of Ion Beams in an RFQ Cooler and Their Transport to the EBIS Charge Breeder	ion, rfq, emittance, radio-frequency	248
	K.H. Yoo, M. Chung UNIST, Ulsan, Republic of Korea H.J. Son IBS, Daejeon, Republic of Korea
	In rare isotope accelerator facilities, an RFQ cooler is often used to manipulate ions. The RFQ cooler is a de-vice to effectively cool and confine ions in gaseous envi-ronment. The RFQ cooler provides a radial electric force to the beam by applying RF voltages to the quadrupole electrode structures, and axial force by applying different DC voltages to the segmented electrodes. The ions are trapped inside the potential well of the RFQ cooler formed by the DC fields, so that they have more colli-sions with the buffer gas. Several important parameters such as transverse emittance can be improved when ion beams are extracted from the RFQ cooler. In order to design an efficient RFQ cooler, which can properly match the ion beams into the EBIS charge breeder, it is essential to analyze evolutions of the transverse emittance and transmission efficiency through the RFQ cooler. Moreo-ver, to minimize emittance growth and maximize trans-mission efficiency, the beam transport line to the EBIS charge breeder needs to be optimized. In this work, we study the methods to apply the mechanism of buffer gas cooling in RFQ cooler to G4beamline and the beam transport line to EBIS charge breeder to TRACK.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR012
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MOPMR016	A New Approach for the Electron Beam Diagnostic Using Diffraction Radiation Disphase Target	target, radiation, detector, diagnostics	261
	D.A. Shkitov, G.A. Naumenko, A. Potylitsyn TPU, Tomsk, Russia J. Urakawa KEK, Ibaraki, Japan
	Funding: The work was partially supported by the RFBR grant No 15-52-50028. Since 1995, when the diffraction radiation (DR) from relativistic particles was first observed, the development of new approaches using the DR for charged particle beam diagnostics is continued. The DR appears when charged particle moves close to the media and the electromagnetic field interacts with it. A rather well-known non-invasive diagnostic method of transversal bunch size is to use a slit target. In paper the optical DR from disphase target was proposed to use for non-invasive diagnostics of high energy electron beam. Disphase target consists of the two rectangular flat plates inclined with respect to each other at an angle compared with 1/g, where g is the Lorentz-factor. Recently the feasibility of the disphase target usage for the 6 MeV electron beam size diagnostics was investigated*. In this report we present the further research of the disphase target beam diagnostics. The simulations of the spectral-angular DR characteristics from this target and it application for diagnostics aim are shown. These calculations confirm an applicability of this technique for micron size beam measurements for the case of g>1000. Y. Shibata et al. //PRE 52, 6787 (1995) P. Karataev et al. //PRL 93, 244802 (2004) G. Naumenko et al. //Proc. of PAC TOAD004, 404 (2005) ***E.V. Kornoukhova et al. //JPCS, in press (2016)
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR016
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MOPMR017	Design and Simulations of the Cavity BPM Readout Electronics for the ELI-NP Gamma Beam System	cavity, electron, electronics, linac	264
	M. Cargnelutti, B.B. Baricevic I-Tech, Solkan, Slovenia A. Mostacci University of Rome La Sapienza, Rome, Italy S. Pioli, M. Serio, A. Stella, A. Variola INFN/LNF, Frascati (Roma), Italy
	The Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility will provide a high intensity laser and a very intense gamma beam which will be used in a broad range of experiments. The gamma beam is obtained through incoherent Compton back-scattering of a laser light off a high brightness electron beam provided by a 700MeV warm LINAC. Electrons are accelerated in trains with up to 32 bunches, each one separated by 16ns. In the laser-electron interaction region, every bunch needs to be monitored with a resolution below 1μm RMS. To achieve this performance, a low-Q cavity beam position monitor will be used in combination with a dedicated data acquisition system able to perform bunch-by-bunch beam position measurements with sub-μm resolution. Using fast A/D converters and specific digital filtering, the readout system proposes an alternative measurement concept. The requirements of the system, its design and the results from the simulations will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR017
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MOPMR034	Precise Betastron Tune Measurement in TPS Storage Ring	betatron, storage-ring, radiation, synchrotron-radiation	319
	C.H. Chen, C.H. Chang, J.Y. Chen, M.-S. Chiu, S. Fann, C.H. Huang, T.Y. Lee, C.C. Liang, Y.-C. Liu, F.H. Tseng NSRRC, Hsinchu, Taiwan
	To acquire precise beam orbits from beam position monitors (BPMs) in storage ring is one of the most significant diagnosis to measure beam parameters. However, the precise spectrum analyses from BPM data acquisitions such as betatron tune, dynamics aperture and frequency map '..etc. that are depended on more accurate discrete Fourier transform (DFT) or the fast Fourier transform (FFT). A method of the fast Fourier transform correction (FFTc) was employed for the more accurate spectrum measurement in Taiwan Photon Source (TPS). We perform the accuracy and error analyses of this method from some spectral lines in two window functions. And the precise spectrum for betatron tune measurements and related results will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR034
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MOPMR035	Bunch Length Measurements using a Transverse Deflecting Cavity on VELA	gun, cavity, laser, electron	323
	J.W. McKenzie, S.R. Buckley, L.S. Cowie, P. Goudket, M. Jenkins, B.L. Militsyn, A.J. Moss, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A. Wolski The University of Liverpool, Liverpool, United Kingdom
	The VELA facility at Daresbury Laboratory in the UK includes a 5 MeV/c 2.5 cell S-band photoinjector gun. This gun operates in the "blow-out" regime with a sub-200 fs length drive laser: the resulting bunch length is determined by space-charge effects. We present measurements made with an S-band transverse deflecting cavity to characterise the bunch length as a function of charge, and as a function of the gun operating phase.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR035
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MOPMR037	Analysis of Asymmetry Tolerances and Cross-coupling in Cavity BPMs	coupling, cavity, alignment, dipole	331
	E. Yamakawa, S.T. Boogert, A. Lyapin, L.J. Nevay JAI, Egham, Surrey, United Kingdom S. Syme FMB Oxford, Oxford, United Kingdom
	Geometric asymmetries in cavity BPMs result in a coupling between horizontal and vertical signals, which complicates their usage and may affect both the dynamic range and spatial resolution of the system in both directions. Tolerances to several types of geometric asymmetries have been analysed using a 3D electromagnetic field solver (GdfidL). We report on some of the results and discussed the possible impact of the considered geometrical distortions.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR037
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MOPMR038	Design and Simulation Studies of the Novel Beam Arrival Monitor Pickup at Daresbury Laboratory	pick-up, impedance, laser, FEL	334
	A. Kalinin, S.P. Jamison, T.T. Thakker STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R. Apsimon, G. Burt, A.C. Dexter Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	We present the novel beam arrival monitor pickup design currently under construction at Daresbury Laboratory, Warrington, UK. The pickup consists of four flat electrodes in a transverse gap. CST Particle Studio simulations have been undertaken for the new pickup design as well as a pickup design from DESY, which is used as a reference for comparison. Simulation results have highlighted two advantages of the new pickup design over the DESY design; the signal bandwidth is 25 GHz, which is half that of the DESY design and the response slope is a factor of 1.6 greater. We discuss optimisation studies of the design parameters in order to maximise the response slope for bandwidths up to 50 GHz and present the final design of the pickup.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR038
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MOPMR040	First Steps Towards a Single-Shot Longitudinal Profile Monitor: Study of the Properties of Coherent Smith-Purcell Radiation Using the Surface Current Model	radiation, detector, polarization, background	340
	H. Harrison, G. Doucas, I.V. Konoplev, A.J. Lancaster JAI, Oxford, United Kingdom A. Aryshev, K. Lekomtsev, M. Shevelev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Funding: UK STFC, Leverhulme Trust, Photon and Quantum Basic Research Coordinated Development Program (Ministry of Education, Culture, Sports, Science and Technology, Japan)and JSPS KAKENHI. We propose to use the polarization of coherent Smith-Purcell radiation (cSPr) to separate the signal from background radiation in a single-shot longitudinal bunch profile monitor. We compare simulation and experimental results for the degree of polarization of cSPr generated by a grating with a 1mm periodic structure at the LUCX facility, KEK (Japan). Both experiment and simulation show that the majority of the cSPr signal is polarized in the direction parallel to the grating grooves. The degree of polarization predicted by simulation is higher than the measured result, therefore further investigation is needed to resolve this discrepancy.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR040
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MOPMR044	Optimization of Particle Accelerators (oPAC)	controls, diagnostics, network, synchrotron	350
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485. The optimization of the performance of any particle accelerator critically depends on an in-depth understanding of the beam dynamics, powerful simulation tools and beam diagnostics, as well as a control and data acquisition system that links all the above. The oPAC consortium has carried out collaborative research into these areas, with the aim to optimize the performance of present and future accelerators that lie at the heart of many research infrastructures. The network brought together research centers, universities, and industry partners to jointly train 23 researchers in this interdisciplinary field. This contribution presents selected research highlights from the network's scientific work packages: results from beam dynamics simulations into upgrade scenarios for the LHC and the 3rd generation light sources ALBA and SOLEIL; use of a cryogenic current comparator for low intensity ion beams; advanced beam loss monitors operating in cryogenic environments; and a laser-wire beam profile monitor for H⁻ beams. Finally, it discusses how an open source control system based on a relational database using a dynamic library loader can help enhance overall facility operation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR044
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MOPMR045	High Resolution and Dynamic Range Characterisation of Beam Imaging Systems	optics, laser, electron, target	354
	C.P. Welsch, R.B. Fiorito, J. Wolfenden Cockcroft Institute, Warrington, Cheshire, United Kingdom M. Bergamaschi, R. Kieffer, T. Lefèvre, S. Mazzoni CERN, Geneva, Switzerland R.B. Fiorito, C.P. Welsch, J. Wolfenden The University of Liverpool, Liverpool, United Kingdom P. Karataev, K.O. Kruchinin Royal Holloway, University of London, Surrey, United Kingdom P. Karataev, K.O. Kruchinin JAI, Egham, Surrey, United Kingdom
	Funding: Work supported by the EU under grant agreement 624890 and the STFC Cockcroft Institute core grant ST/G008248/1. Any imaging system requires the use of various optical components to transfer the light from the source, e.g. optical radiation generated by a charged particle beam, to the sensor. The impact of the transfer optics on the image resolution is often not well known. To improve this situation, the point spread function (PSF) of the optical system must be measured, preferably, with high dynamic range. For this purpose we have created an intense, small (~ 1 μm) point source using a high quality laser and special focusing optics; and introduced a digital micro-mirror array in the optical system to substantially increase its dynamic range. The PSFs of optical systems that are currently being developed for high resolution, high dynamic range beam imaging using optical transition and diffraction radiation are measured and compared to Zemax simulations. The goal of these studies is to systematically understand and mitigate any ill effects on the PSF due to aberrations, diffraction and misalignment of the components of the imaging system. We present the results of our measurements and simulations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR045
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MOPMR046	Characterizing Supersonic Gas Jet-based Beam Profile Monitors	ion, vacuum, diagnostics, electron	357
	H.D. Zhang, A.S. Alexandrova, A. Jeff, V. Tzoganis, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom A.S. Alexandrova, A. Jeff, V. Tzoganis, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom A. Jeff CERN, Geneva, Switzerland
	Funding: Work supported by EU under contracts 215080 and 289191, Helmholtz Association (VH-NG-328) and STFC under the Cockcroft Institute core grant ST/G008248/1. The next generation of high power, high intensity accelerators requires non-invasive diagnostics, particularly beam profile monitors. Residual gas-based diagnostics such as ionization beam profile or beam induced fluorescence monitors have been used to replace commonly used scintillating screens. At the Cockcroft Institute an alternative technique using a supersonic gas jet, shaped into a 45o curtain screen, was developed. It has already demonstrated its superior performance in terms of resolution and signal-to-noise ratio in comparison with residual gas monitors in experimental studies. The performance of this type of monitor depends on the achievable jet homogeneity and quality. Using a movable vacuum gauge as a scanner, the dynamic characteristics of the jet are studied. In this paper we also give an analysis of the resolution for this monitor in detail from the theory and ion drift simulation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR046
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MOPMR060	C-Band Deflecting Cavity for Bunch Length Measurement of 2.5 MeV Electron Beam	cavity, vacuum, electromagnetic-fields, coupling	386
	J. Jiang, H.B. Chen, J. Shi, P. Wang, L. Zhang, S.X. Zheng TUB, Beijing, People's Republic of China
	The C-band deflecting cavity designed last year is finished. In this paper, the RF measurement of the cavity is introduced. After tuning, it works well at 5.712GHz with a coupling factor degree around 1.05. And we measured the electromagnetic field with bead-pull method. The flatness of the magnetic field is around 0.9, which is not ideal but meet the requirements of the bunch length measurement. And we propose a method of tuning to make sure both frequency and field flatness.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR060
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MOPMW002	Modeling and Simulation of Broadband RF Cavities in PSpice	cavity, coupling, impedance, storage-ring	392
	J. Harzheim, D. Domont-Yankulova, H. Klingbeil, R. Königstein TEMF, TU Darmstadt, Darmstadt, Germany M. Frey, H. Klingbeil GSI, Darmstadt, Germany
	Barrier bucket systems are planned for the SIS100 Synchrotron (part of the future accelerator facility FAIR) and the ESR storage ring to facilitate several longitudinal beam manipulations [9] [15]. In order to achieve a single-sine gap signal of the desired amplitude and quality, effects in the linear and nonlinear region of the RF systems have to be investigated and included in the design of the overall system. Therefore, the cavities and the amplifier stages are to be modeled in PSpice. In this contribution, a cavity model will be presented. In a first step, a model for the magnetic alloy (MA) ring cores, which highly account for the properties of the cavity, has been found based on measurement data. In a second step, the future setup of the cavity is systematically created using the MA ring core models. The model of the cavity allows simulations in frequency domain as well as time domain. The results show good agreement with former measurements.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW002
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MOPMW003	Thermal Simulation of an Energy Feedback Normal Conducting RF Cavity	cavity, coupling, operation, electron	396
	M. Fakhari, K. Flöttmann, S. Pfeiffer, H. Schlarb DESY, Hamburg, Germany J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany A. Yahaghi CFEL, Hamburg, Germany
	Thermal simulation has been performed for an energy feedback normal conducting RF cavity. The cavity is going to be used as a fast actuator to regulate the arrival time of the electron bunches in fs level in FLASH. By measuring the arrival time jitter of one bunch in a bunch train, the designed cavity apply a correcting accelerating or decelerating voltage to the next bunches. The input power of the cavity is provided by a solid state amplifier and will be coupled to the cavity via a loop on the body. To achieve the fs level precision of the arrival time, the cavity should be able to provide accurate accelerating voltage with a precision of 300 eV. We performed thermal simulation to find out the temperature distribution of the cavity and make sure that heating will not affect its voltage precision. The simulation results show that by using two input loops the coupling constant will vary from 4.11 to 4.13 during the operation of the cavity which effect on the bunchs' arrival time would be less than 0.25 fs. While using just one input loop can lead to an error of about 1 fs.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW003
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MOPMW007	On the Calibration Measurement of Stripline Beam Position Monitor for the ELI-NP Facility	linac, vacuum, electromagnetic-fields, impedance	411
	D. De Arcangelis, F. Cardelli, A. Mostacci, L. Palumbo University of Rome La Sapienza, Rome, Italy
	Stripline Beam Position Monitor (BPM) will be installed in the Compton Gamma Source in construction at the ELI Nuclear Physics facility in Romania. A test bench for the calibration of BPM has been built to characterize the device with stretched wire measurement in order to get the BPM response map. A full S-parameters characterisation is performed as well to measure the electrical offset with the "Lambertson method". This paper discusses the extensive simulations performed with full 3D electromagnetic CAD codes of the above measurements to investigate measurement accuracy, possible measurement artefacts and the beam position reconstruction.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW007
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MOPMW012	Study for a 162.5 MHz Window-Type RFQ	rfq, Windows, cavity, dipole	423
	Q. Fu, P.P. Gan, S.L. Gao, F.J. Jia, H.P. Li, J. Liu, Y.R. Lu, Z. Wang, K. Zhu PKU, Beijing, People's Republic of China
	A window type of four vane radio-frequency quadrupole accelerator has been designed to accelerate 50 mA deuteron beam from 50 keV to 1 MeV. It will operate at 162.5 MHz in CW mode. Compared to the traditional four-vane RFQ, the window-type RFQ is more compact and has higher mode separation without π-mode stabilizing loops or dipole rods. A detailed full 3D model including vane modulation was developed. For the purpose of high shunt impedance, high quality factor and low power dissipation, the RF structure design was optimized by using electromagnetic simulations. Following the EM design optimization, an aluminium model of the window-type RFQ was fabricated and tested.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW012
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MOPMW015	Wakefields Studies of High Gradient X-band Accelerating Structure at SINAP	wakefield, impedance, cavity, FEL	429
	X.X. Huang, W. Fang, Q. Gu, M. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	Shanghai compact hard x-ray free electron laser (CHXFEL)* is now proposed accompanied with a high-gradient accelerating structure, which is the trend of large scale and compact facility. This structure operated at X-band (11424 MHz) holds the promise to achieve high gradient up to 80 MV/m. However, due to its particular property, a more serious wakefields** will be generated, leading to worse beam instability effects. In this paper, the computation of this case will be carried out with simulation. Moreover, analysis and optimization will be adopted to suppress beam instability. * C. Feng, Z. T. Zhao, Chinese Sci Bull, 2010, 55, 221-227. ** K. Bane, SLAC, NLC-Note 9, Feb. 1995.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW015
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MOPMW033	Acoustic Localization of RF Cavity Breakdown: Status and Progress	cavity, collider, experiment, status	470
	P.G. Lane, P. Snopok, Y. Torun Illinois Institute of Technology, Chicago, Illinois, USA A.V. Kochemirovskiy University of Chicago, Chicago, Illinois, USA
	Current designs for muon accelerators require high-gradient RF cavities to be placed in solenoidal magnetic fields. These fields help contain and efficiently reduce the phase space volume of source muons in order to create a usable muon beam for collider and neutrino experiments. It has been found that placing normal conducting RF cavities in strong magnetic fields reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields, it would be helpful to have a diagnostic tool which can localize the source of breakdown sparks inside the cavity. These sparks generate thermal shocks to a small region of the inner cavity wall that can be detected and localized using microphones attached to the outer cavity surface. Presented here are the algorithms for and results from localizing simulated and experimental acoustic data from the Modular Cavity at the MuCool Test Area at Fermilab.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW033
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MOPMW035	Wakefield Excitation in Power Extraction Cavity (PEC) of Co-linear X-band Energy Booster (CXEB) in Time Domain (T3P) with ACE3P	cavity, extraction, electron, booster	477
	T. Sipahi, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA
	In our previous papers we provided the general concept and the design details of our proposed Co-linear X-band Energy Booster (CXEB) as well as more advanced 3D simulations of our system using the frequency domain solvers OMEGA3P and S3P of the ACE3P Suite. Here, using the time domain solver T3P of ACE3P, we provide the single bunch and multiple bunch wakefield excitations resulting from a Gaussian bunch. The related power extraction mechanism for our traveling wave (TW) X-band power extraction cavity (PEC) are also discussed further.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW035
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MOPMW037	FEL Simulation Using Distributed Computing	FEL, electron, GPU, distributed	483
	J. Einstein, S. Biedron, H. Freund, S.V. Milton, P.J.M. van der Slot CSU, Fort Collins, Colorado, USA G. Bernabeu Altayo Fermi National Accelerator Laboratory, Batavia, Illinois, USA S. Biedron University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia J. Einstein Fermilab, Batavia, Illinois, USA P.J.M. van der Slot Twente University, Laser Physics and Non-Linear Optics Group, Enschede, The Netherlands
	While simulation tools are available and have been used regularly for simulating light sources, the increasing availability and lower cost of GPU-based processing opens up new opportunities. This poster highlights a method of how accelerating and parallelizing code processing through the use of COTS software interfaces.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW037
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MOPMW040	Electron Beam Excitation of a Surface Wave in mm-Wave Open Accelerating Structures	electron, detector, vacuum, experiment	494
	M. Dal Forno, G.B. Bowden, C.I. Clarke, V.A. Dolgashev, M.J. Hogan, D.J. McCormick, A. Novokhatski, B.D. O'Shea, S.G. Tantawi, S.P. Weathersby SLAC, Menlo Park, California, USA B. Spataro INFN/LNF, Frascati (Roma), Italy
	Funding: Work supported by the US DOE under contract DE-AC02-76SF00515. As part of research on the physics of rf breakdowns we performed experiments with high gradient traveling-wave mm-wave accelerating structures. The accelerating structures are open, composed of two identical halves separated by an adjustable gap. The electromagnetic fields are excited by an ultra-relativistic electron beam. We observed that a confined travelling-wave mode exists in half of the accelerating structure. The experiments were conducted at FACET facility at SLAC National Accelerator Laboratory. Depending on the gap width, the accelerating structure had beam-synchronous frequencies that vary from 90 to 140 GHz. When we opened the gap by more than half wavelength the synchronous wave remains trapped. Its behavior is consistent with the so called "surface wave". We characterized this beam-wave interaction by several methods: measurement of the radiated rf energy with the pyro-detector, measurement of the spectrum with an interferometer, measurement of the beam deflection by using the beam position monitors and profile monitor.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW040
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MOPMW044	Design of an RF Device to Study the Multipactor Phenomenon	cavity, electron, multipactoring, experiment	507
	D. Amorim Grenoble-INP Phelma, Grenoble, France J.-M. De Conto, Y. Gómez Martínez LPSC, Grenoble Cedex, France
	Multipacting is a parasitic electron avalanche process that may occur in RF devices such as cavities or couplers. As it can be detrimental to the operation of these devices, the accelerator group at LPSC is currently designing a coaxial resonant cavity in order to study this phenomenon. In order to determine the measurable parameters on the cavity, calculations were performed and validated with numerical simulations. In a second time multipacting simulations were conducted to determine if the experiment will allow to observe multipacting.
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MOPMY005	Study of Pretuning and High Power Test of DTL Iris Waveguide Couplers Using a Single Cell Cavity	cavity, DTL, coupling, factory	522
	S.W. Lee, M.S. Champion, Y.W. Kang ORNL, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S.DOE. Six drift tube linac (DTL) cavities have been operating successfully at the Spallation Neutron Source (SNS). Each cavity is fed by a tapered ridge waveguide iris input coupler and a waveguide ceramic disk window. The original couplers and cavities have been in service for more than a decade. Design optimization and tuning of the couplers were initially performed prior to installation and commissioning of the cavities. Since each DTL cavity is unique, expensive, and fully utilized for neutron production, none of the cavity structure is available as a test cavity or a spare. Maintaining spares for operations and for future system upgrade, test setup of the iris couplers for precision tuning is needed. Ideally a smaller cavity structure may be used for pretuning and RF conditioning of the iris couplers as a test cavity or a bridge waveguide. In this paper, study of using a single cell cavity for the iris tuning and conditioning is presented along with the 3D simulation results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY005
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MOPMY007	Mechanical Design and 3-D Coupled RF, Thermal-Structural Analysis of Normal Conducting 704 MHz and 2.1 GHz Cavities for LEReC Linac	cavity, vacuum, software, operation	525
	J.C. Brutus, S.A. Belomestnykh, I. Ben-Zvi, M. Blaskiewicz, J.M. Brennan, A.V. Fedotov, M.C. Grau, C. Pai, L. Snydstrup, J.E. Tuozzolo, B. P. Xiao, T. Xin, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. Two normal conducting cavities operating at 704 MHz and 2.1 GHz will be used for the Low Energy RHIC electron Cooling (LEReC) under development at BNL to improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon. The single cell 704 MHz cavity and the 3-cell 2.1 GHz third harmonic cavity will be used in LEReC to correct the energy spread introduced in the SRF cavity. The successful operation of normal RF cavities has to satisfy both RF and mechanical requirements. 3-D coupled RF-thermal-structural analysis has been performed on the cavities to confirm the structural stability and to minimize the frequency shift resulting from thermal and structural expansion. In this paper, we will present an overview of the mechanical design, results from the RF-thermal-mechanical analysis, progress on the fabrication and schedule for the normal conducting RF cavities for LEReC.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY007
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MOPMY010	RF Design of Normal Conducting 704 MHz and 2.1 GHz Cavities for LEReC Linac	cavity, HOM, vacuum, impedance	532
	B. P. Xiao, I. Ben-Zvi, M. Blaskiewicz, J.M. Brennan, J.C. Brutus, A.V. Fedotov, H. Hahn, G.T. McIntyre, C. Pai, K.S. Smith, J.E. Tuozzolo, Q. Wu, T. Xin, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh Fermilab, Batavia, Illinois, USA S.A. Belomestnykh, I. Ben-Zvi, T. Xin Stony Brook University, Stony Brook, USA V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 and by National Energy Research Scientific Computing Center under contract No. DE-AC02-05CH11231 by US DOE. To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energy RHIC electron Cooler (LEReC) is currently under development at BNL. Two normal conducting cavities, a single cell 704 MHz cavity and a 3 cell 2.1 GHz third harmonic cavity, will be used in LEReC for energy spread correction. Currently these two cavities are under fabrication. In this paper we report the RF design of these two cavities.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY010
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MOPMY013	Design Study of Collector for CEPC 650 MHz Klystron	gun, klystron, operation, interface	540
	S.C. Wang, D.D. Dong, S. Fukuda, G. Pei, O. Xiao, .. Zaib-un-Nisa, Z.S. Zhou IHEP, Beijing, People's Republic of China S. Fukuda KEK, Ibaraki, Japan
	This paper presents the design and simulation of collector for CEPC 650 MHz high-power CW klystron. Power dissipation in collector is optimised by universal beam spread curve using EGUN code, and beam trajectory in collector is verified by Magic code. The thermal analysis is done by ANSYS-CFX, and groove number and water flow rate are optimized by fluid-solid coupled heat transfer simulation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY013
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MOPMY014	Design Study of RF Section and Cavities for Cepc 650 MHz Klystron	klystron, cavity, electron, bunching	543
	O. Xiao Institute of High Energy Physics (IHEP), People's Republic of China D.D. Dong, S. Fukuda, Z.J. Lu, G. Pei, S.C. Wang, .. Zaib-un-Nisa, Z.S. Zhou IHEP, Beijing, People's Republic of China S. Fukuda KEK, Ibaraki, Japan
	An 800 kW CW klystron operating at 650 MHz is de-veloped for CEPC at Institute of High Energy Physics in China. The conceptual design has been finished and the main parameters are presented in this paper. A 1D large signal disk model code, AJDISK, has been used to design and optimize klystron RF section parameters. In addition, the RF cavities have been designed using SUPERFISH, HFSS and CST.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY014
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MOPMY015	Design Study of Electron Gun for CEPC 650 MHz Klystron	gun, klystron, cathode, electron	546
	.. Zaib-un-Nisa, D.D. Dong, Z.J. Lu, G. Pei, S.C. Wang, O. Xiao, Z.S. Zhou IHEP, People's Republic of China S. Fukuda KEK, Ibaraki, Japan
	This paper presents the design and simulation of an electron gun for 800 kW CW klystron of which frequency is 650 MHz for CEPC project. An electron gun with a modulating anode is designed using DGUN software. The uniform beam trajectories, with a beam perveance of 0.64μA/V 3/2 are simulated. We employed a Ba-dispenser cathode of radius 35 mm with Φ10 hole at the center and obtained a current density on cathode less than 0.45 A/cm². The beam trajectories were also simulated over whole tube length with a magnetic field of 207 Gauss. Expecting functions using the modulating anode gun are also described. Proposed beam tester and whole CEPC klystron layout are also shown in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY015
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MOPMY027	Preliminary Design of High-efficiency Klystron for Pohang Accelerator Laboratory (PAL)	cavity, klystron, beam-losses, operation	557
	S.J. Park, J.Y. Choi, Y.D. Joo, K.R. Kim, W. Namkung, C.D. Park PAL, Pohang, Kyungbuk, Republic of Korea M.-H. Cho, J.H. Hwang, T. Seong POSTECH, Pohang, Kyungbuk, Republic of Korea
	Funding: Supported by the Ministry of Science, ICT and Future Planning of Korea. Klystrons for particle accelerators are typically designed to have narrow bandwidths with center frequencies ranging from several hundreds (e.g., 350) MHz to X-band (11.424 GHz). Output powers are from several tens of kW to ~1 MW for CW klystrons and ~100 MW for pulsed ones. The narrow-bandwidth requirement has enabled them to provide high gain (typically 40 - 50 dB) which greatly simplifies the RF drive system. Recently, especially for large-scale accelerator facilities, the klystron efficiency has become one of the most demanding issues. This is because electricity cost occupies a great portion of their operating budgets and the klystron efficiency is one of the important factors determining the electricity consumption of the whole accelerator system. In this regard, we have designed a high-efficiency klystron for use in the PLS-II and PAL XFEL at PAL. The basic scheme is to re-design the cavity system to include multi-cell output cavity. In this article, we report on our preliminary design work to determine major cavity parameters including cell frequencies, inter-cell distances, and coupling to external circuits (coupling beta).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY027
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MOPOR002	Impedance Simulations and Measurements for ThomX Storage Ring	impedance, interface, wakefield, storage-ring	586
	A.R. Gamelin, C. Bruni, V. Chaumat, D. Le Guidec, P. Lepercq, R. Marie LAL, Orsay, France
	Funding: Work is supported by ANR-10-EQPX-51, by grants from Région Ile-de-France, IN2P3 and Pheniics Doctoral School ThomX is a compact Compton Backscattering Source (CBS) which is being built at LAL, Orsay, France. ThomX ring has a short circumference of 18 m and a design energy of 50 MeV. Due to the low energy of the beam and in order to avoid beam degradation it is important to evaluate the ring components impedance. A CST Particle Studio impedance simulation of the different components of the ring (BPM, bellows, optical chamber, etc.) is under way. It will be followed by a bench measurement of the longitudinal and transverse impedance using the coaxial wire method. This paper will detail the preliminary results of the ThomX storage ring impedance simulations and the measurement principle we will use.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR002
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MOPOR003	Simulation Studies and Measurements of Beam Instabilities Caused by the Kicker Impedance at High Intensities in the 3-GeV RCS of J-PARC	impedance, kicker, injection, betatron	589
	P.K. Saha, H. Harada, N. Hayashi, H. Hotchi, M. Kinsho, M. Nomura, Y. Shobuda, F. Tamura, N. Tani, Y. Watanabe, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan
	The transverse impedance of the extraction kickers is a significant beam instability source in the 3-GeV Rapid Cycling Synchrotron of J-PARC. ORBIT code was developed for space charge and beam instability simulations by successfully introducing realistic time dependent machine parameters. The beam instability at high intensities, especially at the designed 1 MW beam power was found be very critical. As there was no practical measure yet to reduce the kicker impedance, a detail simulation studies were done in order to determine realistic machine parameters to suppress the beam instability. The simulation results were found to be very consistent with measurements to successfully accomplish 1 MW beam power. The simulation and beam study results in detail are presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR003
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MOPOR010	Impedance Measurements and Simulations on the TCTP and TDI LHC Collimators	impedance, HOM, embedded, operation	610
	N. Biancacci, F. Caspers, A. Grudiev, J. Kuczerowski, I. Lamas Garcia, A. Lechner, E. Métral, A. Passarelli, A. Perillo Marcone, B. Salvant, J.A. Uythoven CERN, Geneva, Switzerland O. Frasciello, M. Zobov INFN/LNF, Frascati (Roma), Italy A. Mostacci Rome University La Sapienza, Roma, Italy N. Mounet EPFL, Lausanne, Switzerland
	The LHC collimation system is a critical element for the safe operation of the LHC machine and is subject to continuous performance monitoring, hardware upgrade and optimization. In this work we will address the impact on impedance of the upgrades performed on the TDI injection protection collimator, where the absorber material has been changed to mitigate the device heating observed in machine operation, and on selected secondary (TCS) and tertiary (TCT) collimators, where beam position monitors (BPM) have been embedded for faster jaw alignment. Concerning the TDI, we will present the RF measurements performed before and after the upgrade, comparing the result to heating and tune shift beam measurements. For the TCTs, we will study how the higher order modes (HOM) introduced by the BPM addition have been cured by means of ferrite placement in the device. The impedance mitigation campaign has been supported by RF measurements whose results are in good agreement with GdfidL and CST simulations. The presence of undamped low frequency modes is proved not to be detrimental to the safe LHC operation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR010
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MOPOR012	Study of the Beam-Cavity Interaction in the PS 10 MHz RF System	cavity, impedance, feedback, acceleration	618
	G. Favia, H. Damerau, M. Morvillo, C. Rossi CERN, Geneva, Switzerland M. Migliorati University of Rome "La Sapienza", Rome, Italy
	The eleven main accelerating cavities of the Proton Synchrotron (PS) at CERN consist of two ferrite-loaded coaxial λ/4 resonators each. Both resonators oscillate in phase, as their gaps are electrically connected by short bars. They are in addition magnetically coupled via the bias loop used for cavity tuning. The cavities are equipped with a wide-band feedback system, limiting the beam loading, and a further reduction of the beam induced voltage is achieved by relays which short-circuit each half-resonator gap when the cavity is not in use. Asymmetries of the beam induced voltage observed in the two half-cavities indicate that the coupling between the two resonators is not as tight as expected. The total cavity impedance coupling to the beam may be affected differently by the contributions of both resonators. A dedicated measurement campaign with high-intensity proton beam and numerical simulation have been performed to investigate the beam-cavity interaction. This paper reports the result of the study and the work aiming at the development of a model of the system, including the wide-band feedback, which reproduces this interaction.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR012
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MOPOR018	Single Bunch Instability Studies at Diamond Light Source	impedance, coupling, synchrotron, betatron	637
	E. Koukovini-Platia, M. Apollonio, R. Bartolini, R.T. Fielder, I.P.S. Martin DLS, Oxfordshire, United Kingdom R. Bartolini JAI, Oxford, United Kingdom
	Single bunch instability thresholds, the associated coherent tune shifts and the bunch lengthening have been studied at Diamond light source for nominal optics. Measurements were taken under different settings of chromaticity, radio-frequency (RF) voltage and aperture of the insertion devices (IDs). The macro-particle code sbtrack was used to evaluate the instability thresholds and bunch lengthening where different impedance contributions are taken into account such as the resistive wall impedance, a broad-band resonator model and inductive impedance for the longitudinal plane. A comparison of simulation using the developed model impedance with measurements is shown for all cases.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR018
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MOPOR019	Beta Function Measurement and Resonances Induced by Space Charge Force and Lattice Magnets	resonance, space-charge, lattice, emittance	641
	K. Ohmi, K.G. Sonnad KEK, Ibaraki, Japan
	J-PARC MR has been operated at tune (ν_x,ν_y)=(22.40,20.75). A new operating point around (21.4,21.4) has been proposed by simulation studies on space charge effect since 2013. Machine experiments at the operating point has been performed since 2014 and many encouraging results are being obtained. We discuss why new operating point is better than present one from view point of space charge effects.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR019
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MOPOR025	3D Emittances Tailoring Techniques and Optimization with Space Charge for the Future CERN PS Booster Operations with Linac4	injection, emittance, coupling, linac	660
	V. Forte, J.L. Abelleira, E. Benedetto, C. Bracco, M. Cieslak-Kowalska, G.P. Di Giovanni CERN, Geneva, Switzerland
	In the frame of the LIU (LHC Injectors Upgrade) project, the CERN PS Booster is going to be renovated to host a new H⁻ charge-exchange injection from the Linac4. One important feature of the new injection scheme is the possibility to tailor a wide range of 3D emittances for CERN's different users in an intensity span in the order of 5·10⁹ to 1.6·10¹³ protons per PSB ring. This paper gives an overview of 3D multi-turn injection techniques, focusing on the future LHC beams, which aim at reaching high brightness, and on highest intensity beams (ISOLDE), where losses are the main concern. Complete RF capture simulations and transverse injection maps, including space charge effects, are presented and also intended to be used during the commissioning with Linac4.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR025
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MOPOR032	Using of the MENT Method for Reconstruction of 2D Particle Distributions in IFMIF Accelerators	linac, emittance, SRF, HOM	668
	P.A.P. Nghiem, N. Chauvin, L. Ducrot, M. Valette CEA/DSM/IRFU, France
	Beam particles are characterized by their coordinates in real spaces or phase spaces that are at least two-dimensional. It is often necessary to reconstruct such a 2D-distribution from the knowledge of only its projections on some axes, either for making use of tomography measurement results or for setting up an input beam for transport simulations. In this article, the use of the MENT (Maximum Entropy) reconstruction method is reported for the IFMIF accelerators where high intensity beam distributions are far from Gaussian ones.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR032
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MOPOR033	Simulations of Dark Current from the BERLinPro Booster Module	cavity, electron, cathode, booster	671
	M. McAteer, M. Abo-Bakr, B.C. Kuske, A. Neumann HZB, Berlin, Germany
	Funding: Work supported by the German Bundesministerium f\"ur Bildung und Forschung, Land Berlin and grants of Helmholtz Association Dark current emitted from the surface of high-field RF cavities can contribute to radiation levels and cryo budget and can cause damage to sensitive accelerator components such as the photocathode. The superconducting niobium cavities in the booster module of BERLinPro will have surface fields strong enough to produce significant dark current from field emission, so simulations were made using Astra to track the propagation of emitted electrons from the surfaces of the cavities to examine the effects of dark current in the BERLinPro injector. Results of these simulations, including optimization of the layout to reduce propagation of electrons to the cathode and an estimation of power from dark current deposited throughout the injector, are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR033
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MOPOR034	Numerical Space-Charge Compensation Studies and Comparison of Different Models	electron, proton, space-charge, ion	674
	D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner IAP, Frankfurt am Main, Germany
	The design of many Low-Energy Beam Transport sections relies on the presence of space-charge compensation by particles of opposing charge. To improve understanding of the processes involved in the built-up and steady-state, simulations using the Particle-in-Cell code bender were made. We will present the influence of various system parameters on the results. Furthermore, the electron velocity distribution was found to be approximately thermal. The spatial distribution can then be found by solving the Poisson-Boltzmann equation. Such a model for the electron distribution was implemented in a 2D PIC code and applied to typical beam transport situations. We will present results in comparison to the 3D simulations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR034
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MOPOR038	Implications of Resonantly Driven Higher Order Modes on the ESS Beam	HOM, cavity, linac, emittance	683
	A. Farricker, R.M. Jones, N.Y. Joshi UMAN, Manchester, United Kingdom S. Molloy ESS, Lund, Sweden
	The European Spallation Source (ESS) in Lund, Sweden, will be a facility for fundamental physics studies of atomic structure using a spallation source of unparalleled brightness. To achieve this end, a 2.86 ms long pulsed proton beam will be accelerated up to a final energy of 2 GeV using three suites of superconducting cavities. If a Higher Order Mode (HOM) lies on a harmonic of the bunch frequency the HOM will be resonantly driven. This will dilute the beam quality significantly. Errors in fabricating these cavities are inevitable, and this sets a tolerance on how close the HOM can be within a harmonic of the bunch frequency. The baseline design for ESS requires HOMs to be at least 5 MHz from a machine line. Here we provide details of several finite element electromagnetic simulations on the HOMS anticipated in these ESS cavities. We analyse their impact on the beam emittance using a drift-kick-drift model with the potential for relaxed tolerances.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR038
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MOPOR039	Measurement of Beam Phase at FLASH using HOMs in Accelerating Cavities	HOM, cavity, electron, coupling	686
	L. Shi, R.M. Jones UMAN, Manchester, United Kingdom N. Baboi, L. Shi DESY, Hamburg, Germany N.Y. Joshi University of Manchester, Manchester, United Kingdom
	The beam phase relative to the accelerating field is of vital importance for the quality of photon beams produced in modern Free Electron Lasers based on superconducting (SC) cavities. Normally, the phase is determined by detecting the transient field induced by the beam. In this way the phase of each cavity is checked and adjusted typically every few months. In this paper, we present another means of beam phase determination, based on higher order modes (HOMs) excited in the 2nd monopole band by the beam inside the SC cavities. A circuit model of this HOM band is also presented. Various effects on the resolution have been studied. Circuit model simulations indicate the resolution is strongly dependent on the signal to noise ratio. Preliminary experimental results, based on a broadband setup, reveal an approximately 0.1o RMS resolution. These are in good agreement with simulation results. The work will pave the way for a dedicated system of beam phase monitoring, which is under development for the European XFEL. This will be the first implementation of a dedicated beam phase monitor, based on beam-excited HOMs in accelerating cavities.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR039
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MOPOR042	Beam Dynamics Modeling of Drift-tube Linacs with CST Particle Studio	DTL, rfq, linac, injection	689
	S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	The CST Studio provides convenient tools for self-consistent 3D modeling of accelerators, even large ones. Here we demonstrate this approach for the LANSCE drift-tube linac (DTL) taken as an example. The RF fields in 3D models of full DTL tanks are calculated and tuned with MicroWave Studio (MWS). Beam dynamics in the DTL is modeled with Particle Studio for bunches and bunch trains with realistic initial beam distributions using the MWS-calculated RF fields and quadrupole magnetic fields. The output beam parameters and locations of particle losses are calculated and compared for different beam distributions. Our main emphasis is on the formation of low-energy tails (longitudinal halo) and their interaction with regular bunches. Such effects are usually not taken into account in standard multi-particle phase-space codes.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR042
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MOPOW003	RF Phase Jitter Consideration in Bunch Compression	klystron, electron, linac, FEL	704
	T.K. Charles, D.M. Paganin Monash University, Faculty of Science, Clayton, Victoria, Australia M.J. Boland, R.T. Dowd SLSA, Clayton, Australia
	Error propagation of RF phase jitter is analysed for various linac layout configurations and the sensitivity of the compression ratio due to RF phase jitter is analysed. Multiple sources of jitter have the opportunity to destructively interfere, and (perhaps counter intuitively) found to not add in quadrature. Results are compared to Elegant simulations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW003
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MOPOW004	Electron Trajectory Caustic Formation Resulting in Current Horns present in Bunch Compression	electron, FEL, linac, wakefield	708
	T.K. Charles, D.M. Paganin Monash University, Faculty of Science, Clayton, Victoria, Australia M.J. Boland, R.T. Dowd SLSA, Clayton, Australia
	Current horns are ubiquitous in Free Electron Laser (FEL) bunch compression. In this paper, we analyse the formation of these current spikes and identify the cause as caustic formation in the electron trajectories. We also present a possible solution to avoid or mitigate the current horns from developing through using optical linearization.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW004
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MOPOW009	Studies of Harmonic Lasing Self-seeded FEL at FLASH2	undulator, FEL, electron, radiation	725
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	A concept of the Harmonic Lasing Self-Seeded (HLSS) FEL was proposed in,. A gap-tunable undulator is divided into two parts such that the first part is tuned to a sub-harmonic of the second part. Harmonic lasing occurs in the exponential gain regime in the first part of the undulator, also the fundamental stays well below saturation. In the second part of the undulator the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is reduced by a significant factor depending on harmonic number but the saturation power is still as high as in the reference case of lasing at the fundamental in the whole undulator, i.e. the spectral brightness increases. Application of the post-saturation tapering would allow to generate higher peak power than in SASE mode due to an improved longitudinal coherence. We present feasibility study of the application of the HLSS FEL scheme at FLASH2 and show that it allows to achieve a higher power and a smaller bandwidth than in a standard SASE regime. First experimental tests are eventually discussed. E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 15 (2012) 080702 ** E.A. Schneidmiller and M.V. Yurkov, "Harmonic Lasing Self-Seeded FEL", Proc. of FEL2013 Conf., New York, USA
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW009
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MOPOW011	Operation of Free Electron Laser FLASH Driven by Short Electron Pulses	radiation, electron, undulator, laser	732
	V. Balandin, G. Brenner, C. Gerth, N. Golubeva, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov DESY, Hamburg, Germany E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Rönsch-Schulenburg, J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	The program of low charge mode of operation is under development at free electron laser FLASH aiming in single mode radiation pulses. A short pulse photoinjector laser has been installed at FLASH allowing production of ultrashort electron pluses with moderate compression factor of the beam formation system. Here we present pilot results of free electron laser FLASH operating at the wavelength of 13.1 nm and driven by 70 pC electron bunches. Relevant theoretical analysis has been performed showing good agreement with experimental results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW011
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MOPOW027	Generation of Coherent Mode-locked Radiation in a Seeded Free Electron Laser	electron, radiation, FEL, laser	777
	Z. Wang, Z.T. Zhao SINAP, Shanghai, People's Republic of China D. Xiang Shanghai Jiao Tong University, Shanghai, People's Republic of China
	We present the promise of generating mode-locked multichromatic radiations in a seeded free electron laser based on high gain harmonic generation (HGHG). 3D start-to-end simulations have been carried out and analysis & comparisons have been made to have a research on the properties of each system. In these schemes, either the electron beam density or the seed laser intensity is modulated to produce a coherent radiation pulse train that yields multiple spectral lines in FEL output. Stable peak power at gigawatt level can be generated in the undulator finally.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW027
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MOPOW029	The Soft X-ray Self-seeding System Design for SXFEL User Facility	undulator, FEL, electron, photon	785
	K.Q. Zhang, T. Liu, D. Wang SINAP, Shanghai, People's Republic of China Y. Feng SLAC, Menlo Park, California, USA
	X-ray free electron laser driven by SASE probes the evolution of the new generation light source in high brightness, transverse coherence. However, since SASE achieves lasing from random shotnoise, Poor longitudinal coherence and relative wide bandwidth of SASE FEL limit the operation of many type experiments. Self-seeding as a promising scheme produces longitudinal coherence and even narrower bandwidth radiation by a monochromatic seeding instead of external seeding. The self-seeding system design based on the grating monochromator is carried out for SXFEL user facility across the photon energy from 800-1200 eV. The grating monochromator with a resolution power of 〖10〗^-4 can provide a monochromatic seeding pulse to the seeding undulator. The layout design and simulations of the scheme are presented. It is showing that the self-seeding system for SXFEL user facility is able to improve SASE FEL longitudinal coherence significantly.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW029
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MOPOW036	Design Optimization of an X-band based FEL	linac, FEL, emittance, gun	793
	A.A. Aksoy Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey A. Latina, J. Pfingstner, D. Schulte CERN, Geneva, Switzerland Z. Nergiz Nigde University, Nigde, Turkey
	A design effort for a new generation of compact, cost-effective, power-efficient FEL facilities, based on X-band technology, has been launched. High-frequency X-band acceleration implies strong wakefields, tight alignment and mechanical tolerances, and challenging stability issues. In this paper a design is proposed for the injector and the linacs, including the two bunch compressors. RF gun and injector simulations have been performed, successfully meeting the stringent requirements in terms of minimum projected emittance, sliced emittance and minimum bunch length. In the design of the linac and bunch compressors wakefield effects and misalignment have been taken into account. Start-to-end tracking simulations through the optimized lattice are presented and discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW036
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MOPOW037	Developments in the CLARA FEL Test Facility Accelerator Design and Simulations	linac, FEL, space-charge, undulator	797
	P.H. Williams, D. Angal-Kalinin, A.D. Brynes, J.A. Clarke, F. Jackson, J.K. Jones, J.W. McKenzie, B.L. Militsyn, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.B. Appleby UMAN, Manchester, United Kingdom B. Kyle University of Manchester, Manchester, United Kingdom
	We present recent developments in the accelerator design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. In order to prioritise FEL schemes requiring the shortest electron bunches, the layout has changed significantly to enable compression at higher energy. Four proposed modes of operation are defined and tracked from cathode to FEL using ASTRA. Supplementing these baseline mode definitions with CSR-enabled codes (such as CSRTRACK) where appropriate is in progress. The FEL layout is re-optimised to include shorter undulators with delay chicanes between each radiator.
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MOPOW040	High Efficiency, High Brightness X-ray Free Electron Lasers via Fresh Bunch Self-Seeding	electron, undulator, extraction, photon	805
	C. Emma, C. Pellegrini UCLA, Los Angeles, USA M.W. Guetg, A.A. Lutman, A. Marinelli, C. Pellegrini, J. Wu SLAC, Menlo Park, California, USA
	High efficiency, terawatt peak power X-ray Free Electron Lasers are a promising tool for enabling single molecule imaging and nonlinear science using X-rays. Increasing the efficiency of XFELs while achieving good longitudinal coherence can be achieved via self-seeding and undulator tapering. The efficiency of self-seeded XFELs is limited by two factors: the ratio of seed power to beam energy spread and the ratio of seed power to shot noise power. We present a method to overcome these limitations by producing a strong X-ray seed and amplifying it with a small energy spread beam. This is achieved by selectively suppressing lasing for part of the bunch in the SASE section. In this manner we can saturate with the seeding electrons and amplify the strong seed with 'fresh' electrons downstream of the monochromator. Simulations of this scenario are presented for two systems, an optimal superconducting undulator design and the LCLS. In the case of the LCLS we examine how betatron oscillations leading to selective suppression are induced by using the transverse wakefield of a parallel plate dechirper. We also discuss extending the selective suppression scheme to chirped electron bunches.
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MOPOY003	Study of Achieving Low Energy Beam by Energy Degradation and Direct Resonance Extraction in a Compact Ring	extraction, space-charge, resonance, synchrotron	850
	G.R. Li, X.W. Wang, Z. Yang, H.J. Yao, Q. Zhang, S.X. Zheng TUB, Beijing, People's Republic of China X. Guan Tsinghua University, Beijing, People's Republic of China
	We have designed a compact proton synchrotron(7~230 MeV) for applications like proton therapy and space environment study. These applications may require slow extraction from 10~230 MeV. Traditionally, the low energy beam(10~70 MeV) is achieved by energy degradation from high energy beam which may cause beam lose and energy spread increase, because the beam quality may suffer from magnetic remanence, power ripple and strong space charge effects in low energy stage. To achieve high quality beam directly from resonance extraction, we study these effects by performing multi-particle simulation. Methods of improving beam quality are discussed.
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MOPOY010	Simulations and Measurements of Stopbands in the Fermilab Recycler	resonance, space-charge, proton, operation	864
	R. Ainsworth, P. Adamson, K.J. Hazelwood, I. Kourbanis, E.G. Stern Fermilab, Batavia, Illinois, USA
	Fermilab has recently completed an upgrade to the complex with the goal of delivering 700 kW of beam power as 120 GeV protons to the NuMI target. A major part of boosting beam power is to use the Fermilab Recycler to stack protons. Simulations focusing on the betatron resonance stopbands are presented taking into account different effects such as intensity and chromaticity. Simulations are compared with measurements.
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MOPOY012	Space Charge Simulations in the Fermilab Recycler for PIP-II	space-charge, proton, booster, experiment	870
	R. Ainsworth, P. Adamson, I. Kourbanis, E.G. Stern Fermilab, Batavia, Illinois, USA
	Proton Improvement Plan-II (PIP-II) is Fermilab's plan for providing powerful, high-intensity proton beams to the laboratory's experiments. Upgrades are foreseen for the recycler which will cope with bunches containing fifty percent more beam. Of particular concern is large space charge tune shifts caused by the intensity increase. Simulations performed using Synergia are detailed focusing on the space charge footprint.
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MOPOY013	Modeling Longitudinal Dynamics in the Fermilab Booster Synchrotron	booster, impedance, emittance, synchrotron	873
	J.-F. Ostiguy, C.M. Bhat, V.A. Lebedev Fermilab, Batavia, Illinois, USA
	Funding: Work performed under U.S. Government contract DE-AC02-07CH11359 The PIP-II project will replace the existing 400 MeV linac with a new, CW-capable, 800 MeV superconducting one. With respect to current operations, a 50% increase in beam intensity in the rapid cycling Booster synchrotron is expected. Booster batches are combined in the Recycler ring; this process limits the allowed longitudinal emittance of the extracted Booster beam. To suppress eddy currents, the Booster has no beam pipe; magnets are evacuated, exposing the beam to core laminations and this has a substantial impact on the longitudinal impedance. Noticeable longitudinal emittance growth is already observed at transition crossing. Operation at higher intensity will likely necessitate mitigation measures. We describe systematic efforts to construct a predictive model for current operating conditions. A longitudinal only code including a laminated wall impedance model, space charge effects, and feedback loops is developed. Parameter validation is performed using detailed measurements of relevant beam, rf and control parameters. An attempt is made to benchmark the code at operationally favorable machine settings.
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MOPOY016	HSI RFQ Upgrade for the UNILAC Injection to FAIR	rfq, bunching, emittance, ion	877
	C. Zhang, L. Groening, O.K. Kester, S. Mickat, H. Vormann GSI, Darmstadt, Germany M. Baschke, H. Podlech, U. Ratzinger, R. Tiede IAP, Frankfurt am Main, Germany
	As an injector to the future FAIR facility, the UNILAC accelerator is required to deliver ion beams with high intensities as well as good beam quality. The electrodes of the current HSI RFQ are exhausted and the current RFQ itself is assigned to be one bottle-neck for improving the brilliance performance of the whole linac. Based on the so-called NFSP (New Four-Section Procedure) method, a new RFQ electrode design has been developed and optimized for 20 emA, U⁴⁺ beams at the RFQ entrance. Since only the electrodes will be replaced, the RFQ length has been kept unchanged. Even with a lowered inter-vane voltage, the new RFQ design has achieved better beam performance compared to the previous design. This paper will focus on the performed study with respect to beam dynamics.
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MOPOY020	Prototype Design of a Newly Revised CW RFQ for the High Charge State Injector at GSI	rfq, operation, resonance, impedance	889
	D. Koser, H. Podlech IAP, Frankfurt am Main, Germany P. Gerhard, L. Groening, O.K. Kester GSI, Darmstadt, Germany
	Within the scope of the FAIR project (Facility for Antiproton and Ion Research) at GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, the front end of the existing High Charge State Injector (HLI) is planned to be upgraded for cw operation. The required newly revised 4-Rod RFQ structure is currently being designed at the Institute for Applied Physics (IAP) of the Goethe University of Frankfurt. It will be operated with a 100 kW power amplifier at 108 MHz. At first instance a dedicated 4-stem prototype, which is based on the RFQ design for MYRRHA* and FRANZ*, is planned to be manufactured in order to validate the simulated RF performance, thermal behavior and mechanical characteristics in continuous operation. The RF simulations as well as basic thermal simulations are done using CST Studio Suite. In order to prevent oscillations of the electrodes mechanical eigenmodes are analyzed using ANSYS Multiphysics. In addition the ANSYS software allows more sophisticated simulations regarding the cooling capability by considering fluid dynamics in water cooling channels, thus providing a more detailed thermal analysis. C. Zhang, H. Podlech, New Reference Design of the European ADS RFQ Accelerator For MYRRHA, IPAC2014 **M. Heilmann et al., A Coupled RFQ-IH Cavity for the Neutron Source FRANZ, IPAC2013
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MOPOY027	Emittance Measurement with Wire Scanners at C-ADS Injector-I	emittance, rfq, beam-transport, background	910
	H. Geng, C. Meng, Y.F. Sui, F. Yan, L. Yu, Y.L. Zhao IHEP, Beijing, People's Republic of China
	The transverse emittance at C-ADS injector-I has been measured by the wire scanners at the Medium Energy Beam Transport-I (MEBT1). We have studied the effect of different fitting methods for obtaining the beam sizes on the emittance result, the result will be presented in this paper. The validation study of the quad-scan method with the presence of space charge effect at 10 mA will also be shown, and finally the quad-scan results will be compared with the multi-wire results.
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MOPOY031	Emittance Measurement with Double-Slit Method in CADS Injector-I	emittance, solenoid, rfq, linac	922
	C. Meng, H. Geng, Z. Xue, F. Yan, L. Yu, Y.L. Zhao IHEP, Beijing, People's Republic of China
	The C-ADS accelerator is a CW (Continuous-Wave) proton linac with 1.5 GeV in beam energy, 10 mA in beam current, and 15 MW in beam power. CADS Injector-I accelerator is a 10-mA 10-MeV CW proton linac, which uses a 3.2-MeV normal conducting 4-Vane RFQ and superconducting single-spoke cavities for accelerating. The 5MeV test stand of CADS accelerator Injector I is composed of an ion source, a LEBT, a 325MHz RFQ, a MEBT, a cryogenic module (CM1) of seven SC spoke cavities (β=0.12) , seven SC solenoids, seven cold BPMs and a beam dump. Emittance measurement is very important for the understanding of beam behavior and matching to the next accelerating section. Detailed emittance measurement with double-slit method after CM1 are presented in this paper.
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MOPOY032	Beam Twiss Measurement With Ws Including Space Charge Effect	experiment, space-charge, lattice, rfq	925
	Y.L. Zhao, H. Geng, C. Meng, F. Yan IHEP, Beijing, People's Republic of China
	Wire Scanners (WS) are used to measure beam profile and calculate the transverse Twiss parameters at the entrance of MEBT1 in the CADS injector I test stand. As to data process, the traditional method with transfer map doesn't consider the space charge effect. But, as we know, space charge effect can't be neglected for high intensity accelerators. In this paper, optimization algorithm is used in beam emittance measurement.
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MOPOY033	Design Study on an Injector RFQ for Heavy Ion Accelerator Facility	rfq, cavity, ion, heavy-ion	928
	W. Ma, Y. He, L. Lu, X.B. Xu, Z.L. Zhang, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China
	A Low Energy Accelerator Facility (LEAF) was launched as a pre-research facility for High Intensity heavy ion Accelerator Facility (HIAF). The LEAF consists of a 2-mA U³⁴⁺ electron cyclotron resonance (ECR) type ion source with 300-kV extraction voltage, a low energy beam transport (LEBT) line with a multi-harmonic buncher (MHB), a CW 81.25MHz radio frequency quad-rupole (RFQ) accelerator which could accelerate heavy ions from 14 keV/u up to 500 keV/u, a triplet magnet for medium energy beam transport and an experimental platform for nuclear physics. After describing the selected structure, an octagonal cavity with π-mode stabilizing loop (PISL) type structure was adopted and simulated. In this paper, the detailed electromagnetic design and ther-mal simulation of the LEAF-RFQ will be reported.
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Paper

Title

Other Keywords

Page

MOZA01

Simulated Beam-beam Limits for Circular Lepton and Hadron Colliders

collider, luminosity, lepton, hadron

27

K. Ohmi
KEK, Ibaraki, Japan

The beam-beam limit is one of the most important collider parameters. For lepton colliders the empirical tune shift limits are higher than for hadron colliders, which has been attributed to strong radiation damping. The beam-beam limit in hadron colliders, like the LHC, can be affected by noise. For future higher-energy colliders, like FCC-hh or SppC, the limit can be higher or lower, in the presence of still rather weak synchrotron radiation. For circular lepton colliders, like DAΦNE, SuperKEKB, FCC-ee or CepC, the effect of large Piwinski angle, and crab waist, as well as the dependence of the beam-beam limit on the number of interaction points are important questions. This presentation reviews the state of the art in weak-strong, quasi-strong-strong and strong-strong beam-beam simulations and reports the various dependencies of the simulated beam-beam limit on the aforementioned parameters.

Slides MOZA01 [4.453 MB]

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MOOCB01

PACMAN Project: A New Solution for the High-accuracy Alignment of Accelerator Components

alignment, quadrupole, target, collider

58

H. Mainaud Durand, K. Artoos, M.C.L. Buzio, D. Caiazza, N. Catalán Lasheras, A. Cherif, I.P. Doytchinov, J.-F. Fuchs, A. Gaddi, N. Galindo Munoz, J. Gayde, S.W. Kamugasa, M. Modena, P. Novotny, S. Russenschuck, C. Sanz, G. Severino, D. Tshilumba, V. Vlachakis, M. Wendt, S. Zorzetti
CERN, Geneva, Switzerland

The beam alignment requirements for the next generation of lepton colliders have become increasingly challenging. As an example, the alignment requirements for the three major collider components of the CLIC linear collider are as follows. Before the first beam circulates, the Beam Position Monitors (BPM), Accelerating Structures (AS)and quadrupoles will have to be aligned up to 10 μm w.r.t. a straight line over 200 m long segments, along the 20 km of linacs. PACMAN is a study on Particle Accelerator Components' Metrology and Alignment to the Nanometre scale. It is an Innovative Doctoral Program, funded by the EU and hosted by CERN, providing high quality training to 10 Early Stage Researchers working towards a PhD thesis. The technical aim of the project is to improve the alignment accuracy of the CLIC components by developing new methods and tools addressing several steps of alignment simultaneously, to gain time and accuracy. The tools and methods developed will be validated on a test bench. This paper presents the technical systems to be integrated in the test bench, the results of the compatibility tests performed between these systems, as well as the final design of the PACMAN validation bench.

Slides MOOCB01 [9.553 MB]

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MOOCB02

A Lattice Correction Approach through Betatron Phase Advance

lattice, sextupole, dynamic-aperture, betatron

62

W. Guo, S.L. Kramer, F.J. Willeke, X. Yang, L. Yu
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
Most lattice correction algorithms, such as LOCO, rely on the amplitude of the BPM signals. However, these signals are a mixture of the BPM gain and beta-beat. Even though BPM gain can be fitted by analyzing the statistics of all the BPMs in a ring accelerator, we found the uncertainty is on the order of a few percent. On the other hand, the betatron phase advance, which is obtained from the correlation of two adjacent BPMs, is independent of the BPM gain and tilt error. It was found at NSLS-II that the measurement precision of the phase advance is typically 0.001 radian, which corresponds to about 0.2% of beta beat. The phase error can be corrected similarly using a response matrix, and at NSLS-II the phase error can be corrected to <0.005 radian (p-p) in less than half an hour. The same technique can be applied to the nonlinear lattice. By comparing the phase advance differences between the on- and off- orbit lattices, the sextupole strength error can be identified. Simulation and experimental results will be demonstrated in the paper.

Slides MOOCB02 [1.554 MB]

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MOPMB003

Comparison of Coherent Smith-Purcell Radiation and Coherent Transition Radiation

radiation, electron, laser, free-electron-laser

72

V. Khodnevych, N. Delerue
LAL, Orsay, France
O.A. Bezshyyko, V. Khodnevych
National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine

Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01) and the IDEATE International Associated Laboratory (LIA) between France and Ukraine.
Smith-Purcell radiation and Transition Radiation are two radiative phenomenon that occur in charged particles accelerators. For both the emission can be significantly enhanced with sufficiently short pulses and both can be used to measure the form factor of the pulse. We compare the yield of these phenomenon in different configurations and look at their application as bunch length monitors, including background filtering and rejection. We apply these calculations to the specific case of the CLIO Free Electron laser.

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MOPMB004

Comparison of the Smith-purcell Radiation Yield for Different Models

radiation, electron, experiment, detector

75

M.S. Malovytsia, N. Delerue
LAL, Orsay, France
M.S. Malovytsia
KhNU, Kharkov, Ukraine

Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01) and the IDEATE International Associated Laboratory (LIA) France-Ukraine.
Smith-Purcell radiation is used in several applications including the measurement of the longitudinal profile of electron bunches. A correct reconstruction of such profile requires a good understanding of the underlying model. We have compared the leading models of Smith-Purcell radiation and shown that they are in agreement within the experimental errors.

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MOPMB005

Study of Short Bunches at the Free Electron Laser CLIO

radiation, cavity, electron, gun

78

V. Khodnevych, N. Delerue, S. Jenzer
LAL, Orsay, France
J.P. Berthet, F. Glotin, J.-M. Ortega, R. Prazeres
CLIO/ELISE/LCP, Orsay, France
V. Khodnevych
National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine

Funding: The authors are grateful for the funding received from the French ANR (contract ANR-12-JS05-0003-01).
CLIO is a Free Electron Laser based on a thermionic electron gun. In its normal operating mode it delivers electron 8 pulses but studies are ongoing to shorten the pulses to about 1 ps. We report on simulations showing how the pulse can be shortened and the expected signal yield from several bunch length diagnostics (Coherent Transition Radiation, Coherent Smith Purcell Radiation).

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MOPMB006

First Tests of SuperKEKB Luminosity Monitors during 2016 Single Beam Commissioning

luminosity, vacuum, scattering, background

81

D. El Khechen, P. Bambade, A. Blin, P. Cornebise, D. Jehanno, V. Kubytskyi, Y. Peinaud, C. Rimbault
LAL, Orsay, France
Y. Funakoshi, Y. Ohnishi, S. Uehara
KEK, Ibaraki, Japan

The SuperKEKB e⁺e⁻ collider aims to reach a very high luminosity of 8 10³⁵ cm^-2s⁻¹, using highly focused ultra-low emittance bunches colliding every 4ns. Fast luminosity monitoring is required for luminosity feedback and optimisation in presence of dynamic imperfections. The aimed relative precision is about 10^-3 in 1ms, which can be in principle achieved thanks to the very large cross-section of the radiative Bhabha process at zero degree scattering angle. Diamond, Cherenkov and scintillator sensors are to be placed just outside the beam pipe, downstream of the interaction point in both rings, at locations with event rates consistent with the aimed precision and small enough backgrounds from single-beam particle losses. The initial configuration installed for the 2016 "phase 1" single beam commissioning will be described, including the sensors, mechanical setup, readout electronics and first stage DAQ. Preliminary measurements and analysis of beam gas Bremsstrahlung loss data collected with the luminosity monitors will be reported and compared with a detailed simulation, for several experimental conditions during the SuperKEKB commissioning.

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MOPMB007

Diamond Sensor Resolution in Simultaneous Detection of 1,2,3 Electrons at the PHIL Photoinjector Facility at LAL

electron, detector, experiment, target

84

V. Kubytskyi, P. Bambade, S. Barsuk
LAL, Orsay, France
O.A. Bezshyyko, V. Krylov, V. Rodin
National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine

In this paper, we present experimental and numerical studies of the signals from the Poisson-like distributions resulting from electrons incident on a diamond sensor placed near the exit of the PHIL photoinjector facility at LAL. The experiments were performed at the newly commissioned Low Energy Electron TECHnology (LEETECH) platform at PHIL. Bunches of 10x9 electrons are first generated and accelerated to 3.5 MeV by PHIL. The electrons are then filtered in LEETECH by a system of collimators, using a dipole magnet for momentum selection. The diamond sensor is located immediately after the output collimator to collect electrons in the range 2.5-3 MeV. We show that with standard scCVD diamonds of 500 micrometers thickness, the energy losses from the first three MIP (minimum ionizing particle) electrons are clearly resolved. We did not observe distinguishable peaks in cases when a significant fraction of the incident electrons had energies below a MIP. The described technique can be used as complementary approach for calibration of diamond detectors as well as to diagnose and help control accelerated beams in a regime down to a few particles.

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MOPMB009

Electron Beam Probe for the Bunch Length Measurements at BERLinPro

electron, diagnostics, gun, operation

92

D. Malyutin, A.N. Matveenko
HZB, Berlin, Germany

For the successful operation of various accelerator facilities a detailed bunch characterization is required. A complete description can be achieved using various diagnostic systems installed along an accelerator beamline. Ideally the diagnostic should be able to measure parameters of a single bunch in a non-destructive manner. For bunch length measurements this results in a complicated task especially for bunch duration below 1 ps. One of the possible solutions is a diagnostic based on the interaction of a low energy electron beam with electro-magnetic fields of the relativistic bunch. The bunch length can be readily deduced from the resulting scatter. In this paper bunch length measurement technique based on a low energy electron beam is introduced. Results of numerical simulations of measurements are presented. A possible setup of such diagnostic system for BERLinPro facility is proposed.

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MOPMB013

Time-resolved Spectral Observation of Coherent THz Pulses at DELTA

radiation, laser, electron, detector

105

C. Mai, F.H. Bahnsen, M. Bolsinger, F. Götz, S. Hilbrich, M. Höner, M.A. Jebramcik, S. Khan, N.M. Lockmann, A. Meyer auf der Heide, R. Molo, R. Niemczyk, G. Shayeganrad, M. Suski, P. Ungelenk, D. Zimmermann
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF (05K13PEC), the DFG (INST 212/236-1) and the state of NRW.
Coherent THz pulses induced by a laser-electron interac- tion are routinely produced and observed at DELTA, a 1.5- GeV synchrotron light source operated by the TU Dortmund University. At a dedicated THz beamline, measurements using a Fourier-transform spectrometer have been performed between 1 THz and 7 THz. Recently, an ultrafast Schottky- diode detector and a novel polarizing Fourier-transform spec- trometer were installed, which enable turn-by-turn-resolved spectral measurements in the frequency range below 1 THz. The commissioning results of the new spectrometer and simulations are presented.

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MOPMB017

Design Issues for the Optical Transition Radiation Screens for theELI-NP Compton Gamma Source

radiation, electron, linac, laser

118

M. Marongiu, A. Giribono, A. Mostacci, V. Pettinacci
INFN-Roma, Roma, Italy
D. Alesini, E. Chiadroni, F. Cioeta, G. Di Pirro, V.L. Lollo, L. Pellegrino, V. Shpakov, A. Stella, C. Vaccarezza, A. Variola
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
INFN-Roma II, Roma, Italy
L. Palumbo
University of Rome La Sapienza, Rome, Italy

A high brightness electron LINAC is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32, 16 ns spaced, bunches with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation profile monitors. In order to measure the beam properties along the train, the screens must sustain the thermal stress due to the energy deposited by the bunches; moreover the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the analytical studies as well as numerical simulations to investigate the thermal behaviour of the screens impinged by the nominal bunch; the design and the performance of the optical detection line is discussed as well.

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MOPMB018

Metrological Characterization of the Bunch Length Measurement by Means of a RF Deflector at the ELI-NP Compton Gamma source

linac, electron, laser, brightness

122

L. Sabato
U. Sannio, Benevento, Italy
D. Alesini, C. Vaccarezza, A. Variola
INFN/LNF, Frascati (Roma), Italy
P. Arpaia
CERN, Geneva, Switzerland
P. Arpaia, A. Liccardo
Naples University Federico II, Science and Technology Pole, Napoli, Italy
A. Giribono
University of Rome La Sapienza, Rome, Italy
A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
L. Sabato
INFN-Napoli, Napoli, Italy

Bunch length measurement in linac can be carried out using a RF deflector, which provides a transverse kick to the beam. The transverse beam size on a screen, placed after the RF deflector, represents the bunch length. In this paper, the metrological characterization of the bunch length measurement technique is proposed. The uncertainty and the systematic errors are estimated by means of a sensitivity analysis to the measurement parameters. The proposed approach has been validated through simulation by means of ELEGANT code on the parameters interesting for the electron linac of the Compton source at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP).

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MOPMB027

Beam Parameter Measurement After Relocation of S-Band Linear Accelerator

electron, linac, gun, laser

146

I. Nozawa, M. Gohdo, K. Kan, T. Kondoh, J. Yang, Y. Yoshida
ISIR, Osaka, Japan

Ultrashort electron bunches have been applied in many scientific fields including accelerator physics and radiation chemistry. Pulse radiolysis is application in radiation chemistry, which is a pump-probe measurement using an electron bunch and a laser pulse. Our laboratory aims to generate the electron bunches with durations of less-than femtoseconds using an S-band linear accelerator (linac) at Osaka University in order to improve the time resolution of the pulse radiolysis system. Recently, the linac system was relocated for expanding application using ultrashort electron bunches. The parameters of generated electron bunches including the bunch lengths will be reported.

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MOPMB033

The Influence of Strip-line BPMs' Measuring Results Made by Edge of the Ultra-relativistic Electron Beam

electron, wakefield, positron, linac

161

S.Z. Wang, N. Gan, X. Huang
IHEP, Beijing, People's Republic of China

This paper describes the impact on the measuring results of the stripline beam position monitor (BPM) produced by the edge of the ultra-relativistic electron beam when we take the transverse size of the beam into account. Simulations have been made by using the Wakefield Solver of CST Particle Studio. And the result of this influence at different ratio of beam horizontal width σ and the BPM inner diameter a has been obtained. This kind of influence has been observed in the stripline BPMs in the transfer line of Beijing Positron Electron Colliders upgraded version II (BEPCII). The research is useful when we design the inner diameter of the stripline BPMs for ultra-relativistic electron beam, meanwhile it provides reference to distinguish the invalid ones from the measuring results obtained by the stripline BPMs in the ultra-relativistic situation.

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MOPMB037

Beam Position Monitor Design for Dielectric Wakefield Accelerator In THz Range

wakefield, dipole, polarization, controls

171

Q. Gao, H.B. Chen, J. Shi
TUB, Beijing, People's Republic of China
W. Gai
ANL, Argonne, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA

Dielectric based collinear wakefield accelerator have been broadly selected for the THz accelerator due to its simplicity. In order to move the THz accelerators from the current exploratory research into the practical phase, certain common accelerator components are indispensable. Beam Position Monitor (BPM) is one of them. However, most of conventional BPM techniques are hardly scaled down to THz regime. Here we propose a BPM design which uses the dominant dipole mode excited in the dielectric wakefield accelerators to extract information of the beam position.

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MOPMB038

Development of Shoebox BPM for Xi‘an Proton Application Facility

coupling, proton, impedance, closed-orbit

175

W. Wang, X. Guan, W.-H. Huang, X.W. Wang, Z. Yang, H.Y. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China
M.T. Qiu, Z.M. Wang
State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Shannxi, People's Republic of China

In this paper, development of the Shoebox BPM is presented which can be applied for the measurement of turn-by-turn position data, closed orbit and tune of Xi'an Proton Application Facility (XiPAF). The preliminary design of the physical dimensions including the electrode aperture, the pipe aperture and the gap between the two electrodes is performed by calculating their effects on BPM response respectively with the equivalent circuit model. Furthermore, the mechanical structure of the Shoebox BPM is optimized by CST simulation to achieve better performance. The dependency of the BPM sensitivity and zero offset on the frequency is diminished by adding one isolating ring, which decreases coupling capacitance of electrodes and compensates ground capacitance difference of the two electrodes. Finally one prototype of the Shoebox BPM has been fabricated and tested offline. Results show that relative position measurement error due to frequency dependency of sensitivity is less than 1% and absolute measurement error due to frequency dependency of zero offset is expected to be less than 0.1 mm.

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MOPMB042

Design and Simulation of Button Beam Position Monitor for IR-FEL*

vacuum, FEL, electron, electronics

187

X.Y. Liu, P. Lu, B.G. Sun, L.L. Tang, F.F. Wu, Y.L. Yang, T.Y. Zhou, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: * Supported by the National Science Foundation of China (11575181, 11175173)
A new button-type beam position monitor(BPM) was designed for the IR-FEL project. Firstly, the longitudinal size of BPM needs to be short enough to save space because the entire machine of IR-FEL is very compact. And in the matter of installation problem, all four electrodes are deviated 30 degrees from the horizontal axis. Then, according to these two limited conditions and beam parameters, we builded up a simple model and did some simulated calculations to ensure a good performance of position resolution, which should be better than 50μm. The simulations include an estimation of induced signals in both time and frequency domains, horizontal and vertical sensitivities, mapping figures and so on. This button BPM will be manufactured in the near future and then we can do some off-line experiments to test it.
# Corresponding author (email: bgsun@ustc.edu.cn)

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MOPMB046

Design and Calculation Error Analysis of a High Order Mode Cavity Bunch Length Monitor

cavity, positron, linac, electron

196

J.G. Guo, Q. Luo, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: National Science Foundation of China (11375178) and Fundamental Research Funds for the Central Universities (WK2310000046).
A two-cavity bunch length monitor for linac of positron source is designed. Fifth harmonic cavity resonates at 14.28 GHz (fifth harmonic of the linac fundamental frequency 2.856 GHz) with mode TM020, as this mode could provide larger cavity radius. Each cavity equipped with a filter to suppress unwanted signal. An improved bunch length calculation method was proposed. A simulation was conducted in CST Particle Studio for beam current from 100-300 mA, bunch length from 5-10 ps. Bunch length was calculated and compared by these two methods

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MOPMB049

Beam Experiment of Low Q CBPM Prototype for SXFEL

cavity, HOM, electron, FEL

202

J. Chen, L.W. Lai, Y.B. Leng, L.Y. Yu, R.X. Yuan
SINAP, Shanghai, People's Republic of China

To meet the high resolution beam position measurement requirement of micron or sub-micron for shanghai soft X-ray free electron laser (SXFEL) under construction, the cavity beam position monitor (CBPM) operating at C-band and the corresponding electronic has been designed by SINAP. In this paper, the design and optimize of the newly low Q cavity BPM is mentioned, the beam test was conducted on the Shanghai Deep ultraviolet free electron laser (SDUV-FEL) facility. CBPM signal processors including broadband oscilloscope and home-made digital BPM processor have been used to evaluate the system performance as well. The beam experimental result, which matched with MAFIA simulation very well, will be presented and discussed in this paper.

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MOPMB050

Design of Ultra-wideband Amplifier in RF Front End for Bunch-by-bunch Measurement

power-supply, impedance, experiment, synchrotron-radiation

205

Y. Yang, Y.B. Leng, Y.B. Yan
SSRF, Shanghai, People's Republic of China

RF front end is one of the key technologies in beam diagnosis, especially in bunch-by-bunch measurement at storage ring. This paper gives the design of ultra-wideband amplifier in RF front end for bunch-by-bunch measurement at SSRF. Simulation have been done to verify the performance of this design.

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MOPMB054

A High Sensitivity Faraday Cup for Ultrashort Electron Bunches

electron, gun, laser, experiment

214

S. Setiniyaz, I.H. Baek, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, H.W. Kim, S.V. Miginsky, J.H. Nam, S. Park, N. Vinokurov
KAERI, Daejon, Republic of Korea
S.V. Miginsky, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

The UED (Ultrafast Electron Diffraction) beamline of KAERI (Korea Atomic Energy Research Institute) WCI (World Class Institute) Center has been successfully commissioned. A S-band co-axial RF photogun with 1.5 cylindrically symmetric cells was used to remove multiple modes of the electric filed inside the cavity. It is designed to generate sub-picosecond electron bunches with energy up to 3.3~MeV. We have developed a system consists of an in-air Faraday cup (FC) and a preamplifier for charge measurement. Tests performed utilizing 3.3~MeV electrons show the system were able to measure ultrashort bunches with tens of femtosecond pulse duration at 10 fC sensitivity. In this paper, we shall present the design, calibration and test results of this system.

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MOPMB058

Bunch Arrival Time Monitor Test at PAL-XFEL ITF

pick-up, LLRF, cavity, resonance

223

J.H. Hong, J.H. Han, C. Kim, H. Yang
PAL, Pohang, Kyungbuk, Republic of Korea

Femtosecond resolution electron bunch arrival time monitor (BAM) will be required for the beam-based RF phase feedback during PAL-XFEL operation. Two S-band cavity-type BAMs were manufactured for the test at the PAL-XFEL injector test facility (ITF). The resonance frequencies of the cavities are 2856 MHz and 2826.25 MHz. Electron beam induced signal from the cavities was digitized using a low level RF (LLRF) module. In this paper, the resolution of these cavities are analyzed and a possible improvement for better resolution are discussed.

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MOPMR012

Studies of Buffer Gas Cooling of Ion Beams in an RFQ Cooler and Their Transport to the EBIS Charge Breeder

ion, rfq, emittance, radio-frequency

248

K.H. Yoo, M. Chung
UNIST, Ulsan, Republic of Korea
H.J. Son
IBS, Daejeon, Republic of Korea

In rare isotope accelerator facilities, an RFQ cooler is often used to manipulate ions. The RFQ cooler is a de-vice to effectively cool and confine ions in gaseous envi-ronment. The RFQ cooler provides a radial electric force to the beam by applying RF voltages to the quadrupole electrode structures, and axial force by applying different DC voltages to the segmented electrodes. The ions are trapped inside the potential well of the RFQ cooler formed by the DC fields, so that they have more colli-sions with the buffer gas. Several important parameters such as transverse emittance can be improved when ion beams are extracted from the RFQ cooler. In order to design an efficient RFQ cooler, which can properly match the ion beams into the EBIS charge breeder, it is essential to analyze evolutions of the transverse emittance and transmission efficiency through the RFQ cooler. Moreo-ver, to minimize emittance growth and maximize trans-mission efficiency, the beam transport line to the EBIS charge breeder needs to be optimized. In this work, we study the methods to apply the mechanism of buffer gas cooling in RFQ cooler to G4beamline and the beam transport line to EBIS charge breeder to TRACK.

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MOPMR016

A New Approach for the Electron Beam Diagnostic Using Diffraction Radiation Disphase Target

target, radiation, detector, diagnostics

261

D.A. Shkitov, G.A. Naumenko, A. Potylitsyn
TPU, Tomsk, Russia
J. Urakawa
KEK, Ibaraki, Japan

Funding: The work was partially supported by the RFBR grant No 15-52-50028.
Since 1995, when the diffraction radiation (DR) from relativistic particles was first observed*, the development of new approaches using the DR for charged particle beam diagnostics is continued. The DR appears when charged particle moves close to the media and the electromagnetic field interacts with it. A rather well-known non-invasive diagnostic method of transversal bunch size is to use a slit target**. In paper*** the optical DR from disphase target was proposed to use for non-invasive diagnostics of high energy electron beam. Disphase target consists of the two rectangular flat plates inclined with respect to each other at an angle compared with 1/g, where g is the Lorentz-factor. Recently the feasibility of the disphase target usage for the 6 MeV electron beam size diagnostics was investigated****. In this report we present the further research of the disphase target beam diagnostics. The simulations of the spectral-angular DR characteristics from this target and it application for diagnostics aim are shown. These calculations confirm an applicability of this technique for micron size beam measurements for the case of g>1000.
*Y. Shibata et al. //PRE 52, 6787 (1995)
**P. Karataev et al. //PRL 93, 244802 (2004)
***G. Naumenko et al. //Proc. of PAC TOAD004, 404 (2005)
****E.V. Kornoukhova et al. //JPCS, in press (2016)

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MOPMR017

Design and Simulations of the Cavity BPM Readout Electronics for the ELI-NP Gamma Beam System

cavity, electron, electronics, linac

264

M. Cargnelutti, B.B. Baricevic
I-Tech, Solkan, Slovenia
A. Mostacci
University of Rome La Sapienza, Rome, Italy
S. Pioli, M. Serio, A. Stella, A. Variola
INFN/LNF, Frascati (Roma), Italy

The Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility will provide a high intensity laser and a very intense gamma beam which will be used in a broad range of experiments. The gamma beam is obtained through incoherent Compton back-scattering of a laser light off a high brightness electron beam provided by a 700MeV warm LINAC. Electrons are accelerated in trains with up to 32 bunches, each one separated by 16ns. In the laser-electron interaction region, every bunch needs to be monitored with a resolution below 1μm RMS. To achieve this performance, a low-Q cavity beam position monitor will be used in combination with a dedicated data acquisition system able to perform bunch-by-bunch beam position measurements with sub-μm resolution. Using fast A/D converters and specific digital filtering, the readout system proposes an alternative measurement concept. The requirements of the system, its design and the results from the simulations will be presented.

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MOPMR034

Precise Betastron Tune Measurement in TPS Storage Ring

betatron, storage-ring, radiation, synchrotron-radiation

319

C.H. Chen, C.H. Chang, J.Y. Chen, M.-S. Chiu, S. Fann, C.H. Huang, T.Y. Lee, C.C. Liang, Y.-C. Liu, F.H. Tseng
NSRRC, Hsinchu, Taiwan

To acquire precise beam orbits from beam position monitors (BPMs) in storage ring is one of the most significant diagnosis to measure beam parameters. However, the precise spectrum analyses from BPM data acquisitions such as betatron tune, dynamics aperture and frequency map '..etc. that are depended on more accurate discrete Fourier transform (DFT) or the fast Fourier transform (FFT). A method of the fast Fourier transform correction (FFTc) was employed for the more accurate spectrum measurement in Taiwan Photon Source (TPS). We perform the accuracy and error analyses of this method from some spectral lines in two window functions. And the precise spectrum for betatron tune measurements and related results will be presented.

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MOPMR035

Bunch Length Measurements using a Transverse Deflecting Cavity on VELA

gun, cavity, laser, electron

323

J.W. McKenzie, S.R. Buckley, L.S. Cowie, P. Goudket, M. Jenkins, B.L. Militsyn, A.J. Moss, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A. Wolski
The University of Liverpool, Liverpool, United Kingdom

The VELA facility at Daresbury Laboratory in the UK includes a 5 MeV/c 2.5 cell S-band photoinjector gun. This gun operates in the "blow-out" regime with a sub-200 fs length drive laser: the resulting bunch length is determined by space-charge effects. We present measurements made with an S-band transverse deflecting cavity to characterise the bunch length as a function of charge, and as a function of the gun operating phase.

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MOPMR037

Analysis of Asymmetry Tolerances and Cross-coupling in Cavity BPMs

coupling, cavity, alignment, dipole

331

E. Yamakawa, S.T. Boogert, A. Lyapin, L.J. Nevay
JAI, Egham, Surrey, United Kingdom
S. Syme
FMB Oxford, Oxford, United Kingdom

Geometric asymmetries in cavity BPMs result in a coupling between horizontal and vertical signals, which complicates their usage and may affect both the dynamic range and spatial resolution of the system in both directions. Tolerances to several types of geometric asymmetries have been analysed using a 3D electromagnetic field solver (GdfidL). We report on some of the results and discussed the possible impact of the considered geometrical distortions.

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MOPMR038

Design and Simulation Studies of the Novel Beam Arrival Monitor Pickup at Daresbury Laboratory

pick-up, impedance, laser, FEL

334

A. Kalinin, S.P. Jamison, T.T. Thakker
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Apsimon, G. Burt, A.C. Dexter
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

We present the novel beam arrival monitor pickup design currently under construction at Daresbury Laboratory, Warrington, UK. The pickup consists of four flat electrodes in a transverse gap. CST Particle Studio simulations have been undertaken for the new pickup design as well as a pickup design from DESY, which is used as a reference for comparison. Simulation results have highlighted two advantages of the new pickup design over the DESY design; the signal bandwidth is 25 GHz, which is half that of the DESY design and the response slope is a factor of 1.6 greater. We discuss optimisation studies of the design parameters in order to maximise the response slope for bandwidths up to 50 GHz and present the final design of the pickup.

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MOPMR040

First Steps Towards a Single-Shot Longitudinal Profile Monitor: Study of the Properties of Coherent Smith-Purcell Radiation Using the Surface Current Model

radiation, detector, polarization, background

340

H. Harrison, G. Doucas, I.V. Konoplev, A.J. Lancaster
JAI, Oxford, United Kingdom
A. Aryshev, K. Lekomtsev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: UK STFC, Leverhulme Trust, Photon and Quantum Basic Research Coordinated Development Program (Ministry of Education, Culture, Sports, Science and Technology, Japan)and JSPS KAKENHI.
We propose to use the polarization of coherent Smith-Purcell radiation (cSPr) to separate the signal from background radiation in a single-shot longitudinal bunch profile monitor. We compare simulation and experimental results for the degree of polarization of cSPr generated by a grating with a 1mm periodic structure at the LUCX facility, KEK (Japan). Both experiment and simulation show that the majority of the cSPr signal is polarized in the direction parallel to the grating grooves. The degree of polarization predicted by simulation is higher than the measured result, therefore further investigation is needed to resolve this discrepancy.

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MOPMR044

Optimization of Particle Accelerators (oPAC)

controls, diagnostics, network, synchrotron

350

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

Funding: This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485.
The optimization of the performance of any particle accelerator critically depends on an in-depth understanding of the beam dynamics, powerful simulation tools and beam diagnostics, as well as a control and data acquisition system that links all the above. The oPAC consortium has carried out collaborative research into these areas, with the aim to optimize the performance of present and future accelerators that lie at the heart of many research infrastructures. The network brought together research centers, universities, and industry partners to jointly train 23 researchers in this interdisciplinary field. This contribution presents selected research highlights from the network's scientific work packages: results from beam dynamics simulations into upgrade scenarios for the LHC and the 3rd generation light sources ALBA and SOLEIL; use of a cryogenic current comparator for low intensity ion beams; advanced beam loss monitors operating in cryogenic environments; and a laser-wire beam profile monitor for H⁻ beams. Finally, it discusses how an open source control system based on a relational database using a dynamic library loader can help enhance overall facility operation.

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MOPMR045

High Resolution and Dynamic Range Characterisation of Beam Imaging Systems

optics, laser, electron, target

354

C.P. Welsch, R.B. Fiorito, J. Wolfenden
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M. Bergamaschi, R. Kieffer, T. Lefèvre, S. Mazzoni
CERN, Geneva, Switzerland
R.B. Fiorito, C.P. Welsch, J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom
P. Karataev, K.O. Kruchinin
Royal Holloway, University of London, Surrey, United Kingdom
P. Karataev, K.O. Kruchinin
JAI, Egham, Surrey, United Kingdom

Funding: Work supported by the EU under grant agreement 624890 and the STFC Cockcroft Institute core grant ST/G008248/1.
Any imaging system requires the use of various optical components to transfer the light from the source, e.g. optical radiation generated by a charged particle beam, to the sensor. The impact of the transfer optics on the image resolution is often not well known. To improve this situation, the point spread function (PSF) of the optical system must be measured, preferably, with high dynamic range. For this purpose we have created an intense, small (~ 1 μm) point source using a high quality laser and special focusing optics; and introduced a digital micro-mirror array in the optical system to substantially increase its dynamic range. The PSFs of optical systems that are currently being developed for high resolution, high dynamic range beam imaging using optical transition and diffraction radiation are measured and compared to Zemax simulations. The goal of these studies is to systematically understand and mitigate any ill effects on the PSF due to aberrations, diffraction and misalignment of the components of the imaging system. We present the results of our measurements and simulations.

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MOPMR046

Characterizing Supersonic Gas Jet-based Beam Profile Monitors

ion, vacuum, diagnostics, electron

357

H.D. Zhang, A.S. Alexandrova, A. Jeff, V. Tzoganis, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A.S. Alexandrova, A. Jeff, V. Tzoganis, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
A. Jeff
CERN, Geneva, Switzerland

Funding: Work supported by EU under contracts 215080 and 289191, Helmholtz Association (VH-NG-328) and STFC under the Cockcroft Institute core grant ST/G008248/1.
The next generation of high power, high intensity accelerators requires non-invasive diagnostics, particularly beam profile monitors. Residual gas-based diagnostics such as ionization beam profile or beam induced fluorescence monitors have been used to replace commonly used scintillating screens. At the Cockcroft Institute an alternative technique using a supersonic gas jet, shaped into a 45o curtain screen, was developed. It has already demonstrated its superior performance in terms of resolution and signal-to-noise ratio in comparison with residual gas monitors in experimental studies. The performance of this type of monitor depends on the achievable jet homogeneity and quality. Using a movable vacuum gauge as a scanner, the dynamic characteristics of the jet are studied. In this paper we also give an analysis of the resolution for this monitor in detail from the theory and ion drift simulation.

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MOPMR060

C-Band Deflecting Cavity for Bunch Length Measurement of 2.5 MeV Electron Beam

cavity, vacuum, electromagnetic-fields, coupling

386

J. Jiang, H.B. Chen, J. Shi, P. Wang, L. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China

The C-band deflecting cavity designed last year is finished. In this paper, the RF measurement of the cavity is introduced. After tuning, it works well at 5.712GHz with a coupling factor degree around 1.05. And we measured the electromagnetic field with bead-pull method. The flatness of the magnetic field is around 0.9, which is not ideal but meet the requirements of the bunch length measurement. And we propose a method of tuning to make sure both frequency and field flatness.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR060

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MOPMW002

Modeling and Simulation of Broadband RF Cavities in PSpice

cavity, coupling, impedance, storage-ring

392

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

Barrier bucket systems are planned for the SIS100 Synchrotron (part of the future accelerator facility FAIR) and the ESR storage ring to facilitate several longitudinal beam manipulations [9] [15]. In order to achieve a single-sine gap signal of the desired amplitude and quality, effects in the linear and nonlinear region of the RF systems have to be investigated and included in the design of the overall system. Therefore, the cavities and the amplifier stages are to be modeled in PSpice. In this contribution, a cavity model will be presented. In a first step, a model for the magnetic alloy (MA) ring cores, which highly account for the properties of the cavity, has been found based on measurement data. In a second step, the future setup of the cavity is systematically created using the MA ring core models. The model of the cavity allows simulations in frequency domain as well as time domain. The results show good agreement with former measurements.

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MOPMW003

Thermal Simulation of an Energy Feedback Normal Conducting RF Cavity

cavity, coupling, operation, electron

396

M. Fakhari, K. Flöttmann, S. Pfeiffer, H. Schlarb
DESY, Hamburg, Germany
J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
A. Yahaghi
CFEL, Hamburg, Germany

Thermal simulation has been performed for an energy feedback normal conducting RF cavity. The cavity is going to be used as a fast actuator to regulate the arrival time of the electron bunches in fs level in FLASH. By measuring the arrival time jitter of one bunch in a bunch train, the designed cavity apply a correcting accelerating or decelerating voltage to the next bunches. The input power of the cavity is provided by a solid state amplifier and will be coupled to the cavity via a loop on the body. To achieve the fs level precision of the arrival time, the cavity should be able to provide accurate accelerating voltage with a precision of 300 eV. We performed thermal simulation to find out the temperature distribution of the cavity and make sure that heating will not affect its voltage precision. The simulation results show that by using two input loops the coupling constant will vary from 4.11 to 4.13 during the operation of the cavity which effect on the bunchs' arrival time would be less than 0.25 fs. While using just one input loop can lead to an error of about 1 fs.

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MOPMW007

On the Calibration Measurement of Stripline Beam Position Monitor for the ELI-NP Facility

linac, vacuum, electromagnetic-fields, impedance

411

D. De Arcangelis, F. Cardelli, A. Mostacci, L. Palumbo
University of Rome La Sapienza, Rome, Italy

Stripline Beam Position Monitor (BPM) will be installed in the Compton Gamma Source in construction at the ELI Nuclear Physics facility in Romania. A test bench for the calibration of BPM has been built to characterize the device with stretched wire measurement in order to get the BPM response map. A full S-parameters characterisation is performed as well to measure the electrical offset with the "Lambertson method". This paper discusses the extensive simulations performed with full 3D electromagnetic CAD codes of the above measurements to investigate measurement accuracy, possible measurement artefacts and the beam position reconstruction.

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MOPMW012

Study for a 162.5 MHz Window-Type RFQ

rfq, Windows, cavity, dipole

423

Q. Fu, P.P. Gan, S.L. Gao, F.J. Jia, H.P. Li, J. Liu, Y.R. Lu, Z. Wang, K. Zhu
PKU, Beijing, People's Republic of China

A window type of four vane radio-frequency quadrupole accelerator has been designed to accelerate 50 mA deuteron beam from 50 keV to 1 MeV. It will operate at 162.5 MHz in CW mode. Compared to the traditional four-vane RFQ, the window-type RFQ is more compact and has higher mode separation without π-mode stabilizing loops or dipole rods. A detailed full 3D model including vane modulation was developed. For the purpose of high shunt impedance, high quality factor and low power dissipation, the RF structure design was optimized by using electromagnetic simulations. Following the EM design optimization, an aluminium model of the window-type RFQ was fabricated and tested.

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MOPMW015

Wakefields Studies of High Gradient X-band Accelerating Structure at SINAP

wakefield, impedance, cavity, FEL

429

X.X. Huang, W. Fang, Q. Gu, M. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

Shanghai compact hard x-ray free electron laser (CHXFEL)* is now proposed accompanied with a high-gradient accelerating structure, which is the trend of large scale and compact facility. This structure operated at X-band (11424 MHz) holds the promise to achieve high gradient up to 80 MV/m. However, due to its particular property, a more serious wakefields** will be generated, leading to worse beam instability effects. In this paper, the computation of this case will be carried out with simulation. Moreover, analysis and optimization will be adopted to suppress beam instability.
* C. Feng, Z. T. Zhao, Chinese Sci Bull, 2010, 55, 221-227.
** K. Bane, SLAC, NLC-Note 9, Feb. 1995.

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MOPMW033

Acoustic Localization of RF Cavity Breakdown: Status and Progress

cavity, collider, experiment, status

470

P.G. Lane, P. Snopok, Y. Torun
Illinois Institute of Technology, Chicago, Illinois, USA
A.V. Kochemirovskiy
University of Chicago, Chicago, Illinois, USA

Current designs for muon accelerators require high-gradient RF cavities to be placed in solenoidal magnetic fields. These fields help contain and efficiently reduce the phase space volume of source muons in order to create a usable muon beam for collider and neutrino experiments. It has been found that placing normal conducting RF cavities in strong magnetic fields reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields, it would be helpful to have a diagnostic tool which can localize the source of breakdown sparks inside the cavity. These sparks generate thermal shocks to a small region of the inner cavity wall that can be detected and localized using microphones attached to the outer cavity surface. Presented here are the algorithms for and results from localizing simulated and experimental acoustic data from the Modular Cavity at the MuCool Test Area at Fermilab.

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MOPMW035

Wakefield Excitation in Power Extraction Cavity (PEC) of Co-linear X-band Energy Booster (CXEB) in Time Domain (T3P) with ACE3P

cavity, extraction, electron, booster

477

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

In our previous papers we provided the general concept and the design details of our proposed Co-linear X-band Energy Booster (CXEB) as well as more advanced 3D simulations of our system using the frequency domain solvers OMEGA3P and S3P of the ACE3P Suite. Here, using the time domain solver T3P of ACE3P, we provide the single bunch and multiple bunch wakefield excitations resulting from a Gaussian bunch. The related power extraction mechanism for our traveling wave (TW) X-band power extraction cavity (PEC) are also discussed further.

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MOPMW037

FEL Simulation Using Distributed Computing

FEL, electron, GPU, distributed

483

J. Einstein, S. Biedron, H. Freund, S.V. Milton, P.J.M. van der Slot
CSU, Fort Collins, Colorado, USA
G. Bernabeu Altayo
Fermi National Accelerator Laboratory, Batavia, Illinois, USA
S. Biedron
University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia
J. Einstein
Fermilab, Batavia, Illinois, USA
P.J.M. van der Slot
Twente University, Laser Physics and Non-Linear Optics Group, Enschede, The Netherlands

While simulation tools are available and have been used regularly for simulating light sources, the increasing availability and lower cost of GPU-based processing opens up new opportunities. This poster highlights a method of how accelerating and parallelizing code processing through the use of COTS software interfaces.

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MOPMW040

Electron Beam Excitation of a Surface Wave in mm-Wave Open Accelerating Structures

electron, detector, vacuum, experiment

494

M. Dal Forno, G.B. Bowden, C.I. Clarke, V.A. Dolgashev, M.J. Hogan, D.J. McCormick, A. Novokhatski, B.D. O'Shea, S.G. Tantawi, S.P. Weathersby
SLAC, Menlo Park, California, USA
B. Spataro
INFN/LNF, Frascati (Roma), Italy

Funding: Work supported by the US DOE under contract DE-AC02-76SF00515.
As part of research on the physics of rf breakdowns we performed experiments with high gradient traveling-wave mm-wave accelerating structures. The accelerating structures are open, composed of two identical halves separated by an adjustable gap. The electromagnetic fields are excited by an ultra-relativistic electron beam. We observed that a confined travelling-wave mode exists in half of the accelerating structure. The experiments were conducted at FACET facility at SLAC National Accelerator Laboratory. Depending on the gap width, the accelerating structure had beam-synchronous frequencies that vary from 90 to 140 GHz. When we opened the gap by more than half wavelength the synchronous wave remains trapped. Its behavior is consistent with the so called "surface wave". We characterized this beam-wave interaction by several methods: measurement of the radiated rf energy with the pyro-detector, measurement of the spectrum with an interferometer, measurement of the beam deflection by using the beam position monitors and profile monitor.

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MOPMW044

Design of an RF Device to Study the Multipactor Phenomenon

cavity, electron, multipactoring, experiment

507

D. Amorim
Grenoble-INP Phelma, Grenoble, France
J.-M. De Conto, Y. Gómez Martínez
LPSC, Grenoble Cedex, France

Multipacting is a parasitic electron avalanche process that may occur in RF devices such as cavities or couplers. As it can be detrimental to the operation of these devices, the accelerator group at LPSC is currently designing a coaxial resonant cavity in order to study this phenomenon. In order to determine the measurable parameters on the cavity, calculations were performed and validated with numerical simulations. In a second time multipacting simulations were conducted to determine if the experiment will allow to observe multipacting.

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MOPMY005

Study of Pretuning and High Power Test of DTL Iris Waveguide Couplers Using a Single Cell Cavity

cavity, DTL, coupling, factory

522

S.W. Lee, M.S. Champion, Y.W. Kang
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S.DOE.
Six drift tube linac (DTL) cavities have been operating successfully at the Spallation Neutron Source (SNS). Each cavity is fed by a tapered ridge waveguide iris input coupler and a waveguide ceramic disk window. The original couplers and cavities have been in service for more than a decade. Design optimization and tuning of the couplers were initially performed prior to installation and commissioning of the cavities. Since each DTL cavity is unique, expensive, and fully utilized for neutron production, none of the cavity structure is available as a test cavity or a spare. Maintaining spares for operations and for future system upgrade, test setup of the iris couplers for precision tuning is needed. Ideally a smaller cavity structure may be used for pretuning and RF conditioning of the iris couplers as a test cavity or a bridge waveguide. In this paper, study of using a single cell cavity for the iris tuning and conditioning is presented along with the 3D simulation results.

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MOPMY007

Mechanical Design and 3-D Coupled RF, Thermal-Structural Analysis of Normal Conducting 704 MHz and 2.1 GHz Cavities for LEReC Linac

cavity, vacuum, software, operation

525

J.C. Brutus, S.A. Belomestnykh, I. Ben-Zvi, M. Blaskiewicz, J.M. Brennan, A.V. Fedotov, M.C. Grau, C. Pai, L. Snydstrup, J.E. Tuozzolo, B. P. Xiao, T. Xin, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
Two normal conducting cavities operating at 704 MHz and 2.1 GHz will be used for the Low Energy RHIC electron Cooling (LEReC) under development at BNL to improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon. The single cell 704 MHz cavity and the 3-cell 2.1 GHz third harmonic cavity will be used in LEReC to correct the energy spread introduced in the SRF cavity. The successful operation of normal RF cavities has to satisfy both RF and mechanical requirements. 3-D coupled RF-thermal-structural analysis has been performed on the cavities to confirm the structural stability and to minimize the frequency shift resulting from thermal and structural expansion. In this paper, we will present an overview of the mechanical design, results from the RF-thermal-mechanical analysis, progress on the fabrication and schedule for the normal conducting RF cavities for LEReC.

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MOPMY010

RF Design of Normal Conducting 704 MHz and 2.1 GHz Cavities for LEReC Linac

cavity, HOM, vacuum, impedance

532

B. P. Xiao, I. Ben-Zvi, M. Blaskiewicz, J.M. Brennan, J.C. Brutus, A.V. Fedotov, H. Hahn, G.T. McIntyre, C. Pai, K.S. Smith, J.E. Tuozzolo, Q. Wu, T. Xin, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh
Fermilab, Batavia, Illinois, USA
S.A. Belomestnykh, I. Ben-Zvi, T. Xin
Stony Brook University, Stony Brook, USA
V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 and by National Energy Research Scientific Computing Center under contract No. DE-AC02-05CH11231 by US DOE.
To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energy RHIC electron Cooler (LEReC) is currently under development at BNL. Two normal conducting cavities, a single cell 704 MHz cavity and a 3 cell 2.1 GHz third harmonic cavity, will be used in LEReC for energy spread correction. Currently these two cavities are under fabrication. In this paper we report the RF design of these two cavities.

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MOPMY013

Design Study of Collector for CEPC 650 MHz Klystron

gun, klystron, operation, interface

540

S.C. Wang, D.D. Dong, S. Fukuda, G. Pei, O. Xiao, .. Zaib-un-Nisa, Z.S. Zhou
IHEP, Beijing, People's Republic of China
S. Fukuda
KEK, Ibaraki, Japan

This paper presents the design and simulation of collector for CEPC 650 MHz high-power CW klystron. Power dissipation in collector is optimised by universal beam spread curve using EGUN code, and beam trajectory in collector is verified by Magic code. The thermal analysis is done by ANSYS-CFX, and groove number and water flow rate are optimized by fluid-solid coupled heat transfer simulation.

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MOPMY014

Design Study of RF Section and Cavities for Cepc 650 MHz Klystron

klystron, cavity, electron, bunching

543

O. Xiao
Institute of High Energy Physics (IHEP), People's Republic of China
D.D. Dong, S. Fukuda, Z.J. Lu, G. Pei, S.C. Wang, .. Zaib-un-Nisa, Z.S. Zhou
IHEP, Beijing, People's Republic of China
S. Fukuda
KEK, Ibaraki, Japan

An 800 kW CW klystron operating at 650 MHz is de-veloped for CEPC at Institute of High Energy Physics in China. The conceptual design has been finished and the main parameters are presented in this paper. A 1D large signal disk model code, AJDISK, has been used to design and optimize klystron RF section parameters. In addition, the RF cavities have been designed using SUPERFISH, HFSS and CST.

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MOPMY015

Design Study of Electron Gun for CEPC 650 MHz Klystron

gun, klystron, cathode, electron

546

.. Zaib-un-Nisa, D.D. Dong, Z.J. Lu, G. Pei, S.C. Wang, O. Xiao, Z.S. Zhou
IHEP, People's Republic of China
S. Fukuda
KEK, Ibaraki, Japan

This paper presents the design and simulation of an electron gun for 800 kW CW klystron of which frequency is 650 MHz for CEPC project. An electron gun with a modulating anode is designed using DGUN software. The uniform beam trajectories, with a beam perveance of 0.64μA/V 3/2 are simulated. We employed a Ba-dispenser cathode of radius 35 mm with Φ10 hole at the center and obtained a current density on cathode less than 0.45 A/cm². The beam trajectories were also simulated over whole tube length with a magnetic field of 207 Gauss. Expecting functions using the modulating anode gun are also described. Proposed beam tester and whole CEPC klystron layout are also shown in this paper.

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MOPMY027

Preliminary Design of High-efficiency Klystron for Pohang Accelerator Laboratory (PAL)

cavity, klystron, beam-losses, operation

557

S.J. Park, J.Y. Choi, Y.D. Joo, K.R. Kim, W. Namkung, C.D. Park
PAL, Pohang, Kyungbuk, Republic of Korea
M.-H. Cho, J.H. Hwang, T. Seong
POSTECH, Pohang, Kyungbuk, Republic of Korea

Funding: Supported by the Ministry of Science, ICT and Future Planning of Korea.
Klystrons for particle accelerators are typically designed to have narrow bandwidths with center frequencies ranging from several hundreds (e.g., 350) MHz to X-band (11.424 GHz). Output powers are from several tens of kW to ~1 MW for CW klystrons and ~100 MW for pulsed ones. The narrow-bandwidth requirement has enabled them to provide high gain (typically 40 - 50 dB) which greatly simplifies the RF drive system. Recently, especially for large-scale accelerator facilities, the klystron efficiency has become one of the most demanding issues. This is because electricity cost occupies a great portion of their operating budgets and the klystron efficiency is one of the important factors determining the electricity consumption of the whole accelerator system. In this regard, we have designed a high-efficiency klystron for use in the PLS-II and PAL XFEL at PAL. The basic scheme is to re-design the cavity system to include multi-cell output cavity. In this article, we report on our preliminary design work to determine major cavity parameters including cell frequencies, inter-cell distances, and coupling to external circuits (coupling beta).

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MOPOR002

Impedance Simulations and Measurements for ThomX Storage Ring

impedance, interface, wakefield, storage-ring

586

A.R. Gamelin, C. Bruni, V. Chaumat, D. Le Guidec, P. Lepercq, R. Marie
LAL, Orsay, France

Funding: Work is supported by ANR-10-EQPX-51, by grants from Région Ile-de-France, IN2P3 and Pheniics Doctoral School
ThomX is a compact Compton Backscattering Source (CBS) which is being built at LAL, Orsay, France. ThomX ring has a short circumference of 18 m and a design energy of 50 MeV. Due to the low energy of the beam and in order to avoid beam degradation it is important to evaluate the ring components impedance. A CST Particle Studio impedance simulation of the different components of the ring (BPM, bellows, optical chamber, etc.) is under way. It will be followed by a bench measurement of the longitudinal and transverse impedance using the coaxial wire method. This paper will detail the preliminary results of the ThomX storage ring impedance simulations and the measurement principle we will use.

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MOPOR003

Simulation Studies and Measurements of Beam Instabilities Caused by the Kicker Impedance at High Intensities in the 3-GeV RCS of J-PARC

impedance, kicker, injection, betatron

589

P.K. Saha, H. Harada, N. Hayashi, H. Hotchi, M. Kinsho, M. Nomura, Y. Shobuda, F. Tamura, N. Tani, Y. Watanabe, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

The transverse impedance of the extraction kickers is a significant beam instability source in the 3-GeV Rapid Cycling Synchrotron of J-PARC. ORBIT code was developed for space charge and beam instability simulations by successfully introducing realistic time dependent machine parameters. The beam instability at high intensities, especially at the designed 1 MW beam power was found be very critical. As there was no practical measure yet to reduce the kicker impedance, a detail simulation studies were done in order to determine realistic machine parameters to suppress the beam instability. The simulation results were found to be very consistent with measurements to successfully accomplish 1 MW beam power. The simulation and beam study results in detail are presented in this paper.

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MOPOR010

Impedance Measurements and Simulations on the TCTP and TDI LHC Collimators

impedance, HOM, embedded, operation

610

N. Biancacci, F. Caspers, A. Grudiev, J. Kuczerowski, I. Lamas Garcia, A. Lechner, E. Métral, A. Passarelli, A. Perillo Marcone, B. Salvant, J.A. Uythoven
CERN, Geneva, Switzerland
O. Frasciello, M. Zobov
INFN/LNF, Frascati (Roma), Italy
A. Mostacci
Rome University La Sapienza, Roma, Italy
N. Mounet
EPFL, Lausanne, Switzerland

The LHC collimation system is a critical element for the safe operation of the LHC machine and is subject to continuous performance monitoring, hardware upgrade and optimization. In this work we will address the impact on impedance of the upgrades performed on the TDI injection protection collimator, where the absorber material has been changed to mitigate the device heating observed in machine operation, and on selected secondary (TCS) and tertiary (TCT) collimators, where beam position monitors (BPM) have been embedded for faster jaw alignment. Concerning the TDI, we will present the RF measurements performed before and after the upgrade, comparing the result to heating and tune shift beam measurements. For the TCTs, we will study how the higher order modes (HOM) introduced by the BPM addition have been cured by means of ferrite placement in the device. The impedance mitigation campaign has been supported by RF measurements whose results are in good agreement with GdfidL and CST simulations. The presence of undamped low frequency modes is proved not to be detrimental to the safe LHC operation.

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MOPOR012

Study of the Beam-Cavity Interaction in the PS 10 MHz RF System

cavity, impedance, feedback, acceleration

618

G. Favia, H. Damerau, M. Morvillo, C. Rossi
CERN, Geneva, Switzerland
M. Migliorati
University of Rome "La Sapienza", Rome, Italy

The eleven main accelerating cavities of the Proton Synchrotron (PS) at CERN consist of two ferrite-loaded coaxial λ/4 resonators each. Both resonators oscillate in phase, as their gaps are electrically connected by short bars. They are in addition magnetically coupled via the bias loop used for cavity tuning. The cavities are equipped with a wide-band feedback system, limiting the beam loading, and a further reduction of the beam induced voltage is achieved by relays which short-circuit each half-resonator gap when the cavity is not in use. Asymmetries of the beam induced voltage observed in the two half-cavities indicate that the coupling between the two resonators is not as tight as expected. The total cavity impedance coupling to the beam may be affected differently by the contributions of both resonators. A dedicated measurement campaign with high-intensity proton beam and numerical simulation have been performed to investigate the beam-cavity interaction. This paper reports the result of the study and the work aiming at the development of a model of the system, including the wide-band feedback, which reproduces this interaction.

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MOPOR018

Single Bunch Instability Studies at Diamond Light Source

impedance, coupling, synchrotron, betatron

637

E. Koukovini-Platia, M. Apollonio, R. Bartolini, R.T. Fielder, I.P.S. Martin
DLS, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom

Single bunch instability thresholds, the associated coherent tune shifts and the bunch lengthening have been studied at Diamond light source for nominal optics. Measurements were taken under different settings of chromaticity, radio-frequency (RF) voltage and aperture of the insertion devices (IDs). The macro-particle code sbtrack was used to evaluate the instability thresholds and bunch lengthening where different impedance contributions are taken into account such as the resistive wall impedance, a broad-band resonator model and inductive impedance for the longitudinal plane. A comparison of simulation using the developed model impedance with measurements is shown for all cases.

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MOPOR019

Beta Function Measurement and Resonances Induced by Space Charge Force and Lattice Magnets

resonance, space-charge, lattice, emittance

641

K. Ohmi, K.G. Sonnad
KEK, Ibaraki, Japan

J-PARC MR has been operated at tune (ν_x,ν_y)=(22.40,20.75). A new operating point around (21.4,21.4) has been proposed by simulation studies on space charge effect since 2013. Machine experiments at the operating point has been performed since 2014 and many encouraging results are being obtained. We discuss why new operating point is better than present one from view point of space charge effects.

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MOPOR025

3D Emittances Tailoring Techniques and Optimization with Space Charge for the Future CERN PS Booster Operations with Linac4

injection, emittance, coupling, linac

660

V. Forte, J.L. Abelleira, E. Benedetto, C. Bracco, M. Cieslak-Kowalska, G.P. Di Giovanni
CERN, Geneva, Switzerland

In the frame of the LIU (LHC Injectors Upgrade) project, the CERN PS Booster is going to be renovated to host a new H⁻ charge-exchange injection from the Linac4. One important feature of the new injection scheme is the possibility to tailor a wide range of 3D emittances for CERN's different users in an intensity span in the order of 5·10⁹ to 1.6·10¹³ protons per PSB ring. This paper gives an overview of 3D multi-turn injection techniques, focusing on the future LHC beams, which aim at reaching high brightness, and on highest intensity beams (ISOLDE), where losses are the main concern. Complete RF capture simulations and transverse injection maps, including space charge effects, are presented and also intended to be used during the commissioning with Linac4.

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MOPOR032

Using of the MENT Method for Reconstruction of 2D Particle Distributions in IFMIF Accelerators

linac, emittance, SRF, HOM

668

P.A.P. Nghiem, N. Chauvin, L. Ducrot, M. Valette
CEA/DSM/IRFU, France

Beam particles are characterized by their coordinates in real spaces or phase spaces that are at least two-dimensional. It is often necessary to reconstruct such a 2D-distribution from the knowledge of only its projections on some axes, either for making use of tomography measurement results or for setting up an input beam for transport simulations. In this article, the use of the MENT (Maximum Entropy) reconstruction method is reported for the IFMIF accelerators where high intensity beam distributions are far from Gaussian ones.

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MOPOR033

Simulations of Dark Current from the BERLinPro Booster Module

cavity, electron, cathode, booster

671

M. McAteer, M. Abo-Bakr, B.C. Kuske, A. Neumann
HZB, Berlin, Germany

Funding: Work supported by the German Bundesministerium f\"ur Bildung und Forschung, Land Berlin and grants of Helmholtz Association
Dark current emitted from the surface of high-field RF cavities can contribute to radiation levels and cryo budget and can cause damage to sensitive accelerator components such as the photocathode. The superconducting niobium cavities in the booster module of BERLinPro will have surface fields strong enough to produce significant dark current from field emission, so simulations were made using Astra to track the propagation of emitted electrons from the surfaces of the cavities to examine the effects of dark current in the BERLinPro injector. Results of these simulations, including optimization of the layout to reduce propagation of electrons to the cathode and an estimation of power from dark current deposited throughout the injector, are presented.

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MOPOR034

Numerical Space-Charge Compensation Studies and Comparison of Different Models

electron, proton, space-charge, ion

674

D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner
IAP, Frankfurt am Main, Germany

The design of many Low-Energy Beam Transport sections relies on the presence of space-charge compensation by particles of opposing charge. To improve understanding of the processes involved in the built-up and steady-state, simulations using the Particle-in-Cell code bender were made. We will present the influence of various system parameters on the results. Furthermore, the electron velocity distribution was found to be approximately thermal. The spatial distribution can then be found by solving the Poisson-Boltzmann equation. Such a model for the electron distribution was implemented in a 2D PIC code and applied to typical beam transport situations. We will present results in comparison to the 3D simulations.

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MOPOR038

Implications of Resonantly Driven Higher Order Modes on the ESS Beam

HOM, cavity, linac, emittance

683

A. Farricker, R.M. Jones, N.Y. Joshi
UMAN, Manchester, United Kingdom
S. Molloy
ESS, Lund, Sweden

The European Spallation Source (ESS) in Lund, Sweden, will be a facility for fundamental physics studies of atomic structure using a spallation source of unparalleled brightness. To achieve this end, a 2.86 ms long pulsed proton beam will be accelerated up to a final energy of 2 GeV using three suites of superconducting cavities. If a Higher Order Mode (HOM) lies on a harmonic of the bunch frequency the HOM will be resonantly driven. This will dilute the beam quality significantly. Errors in fabricating these cavities are inevitable, and this sets a tolerance on how close the HOM can be within a harmonic of the bunch frequency. The baseline design for ESS requires HOMs to be at least 5 MHz from a machine line. Here we provide details of several finite element electromagnetic simulations on the HOMS anticipated in these ESS cavities. We analyse their impact on the beam emittance using a drift-kick-drift model with the potential for relaxed tolerances.

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MOPOR039

Measurement of Beam Phase at FLASH using HOMs in Accelerating Cavities

HOM, cavity, electron, coupling

686

L. Shi, R.M. Jones
UMAN, Manchester, United Kingdom
N. Baboi, L. Shi
DESY, Hamburg, Germany
N.Y. Joshi
University of Manchester, Manchester, United Kingdom

The beam phase relative to the accelerating field is of vital importance for the quality of photon beams produced in modern Free Electron Lasers based on superconducting (SC) cavities. Normally, the phase is determined by detecting the transient field induced by the beam. In this way the phase of each cavity is checked and adjusted typically every few months. In this paper, we present another means of beam phase determination, based on higher order modes (HOMs) excited in the 2nd monopole band by the beam inside the SC cavities. A circuit model of this HOM band is also presented. Various effects on the resolution have been studied. Circuit model simulations indicate the resolution is strongly dependent on the signal to noise ratio. Preliminary experimental results, based on a broadband setup, reveal an approximately 0.1o RMS resolution. These are in good agreement with simulation results. The work will pave the way for a dedicated system of beam phase monitoring, which is under development for the European XFEL. This will be the first implementation of a dedicated beam phase monitor, based on beam-excited HOMs in accelerating cavities.

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MOPOR042

Beam Dynamics Modeling of Drift-tube Linacs with CST Particle Studio

DTL, rfq, linac, injection

689

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

The CST Studio provides convenient tools for self-consistent 3D modeling of accelerators, even large ones. Here we demonstrate this approach for the LANSCE drift-tube linac (DTL) taken as an example. The RF fields in 3D models of full DTL tanks are calculated and tuned with MicroWave Studio (MWS). Beam dynamics in the DTL is modeled with Particle Studio for bunches and bunch trains with realistic initial beam distributions using the MWS-calculated RF fields and quadrupole magnetic fields. The output beam parameters and locations of particle losses are calculated and compared for different beam distributions. Our main emphasis is on the formation of low-energy tails (longitudinal halo) and their interaction with regular bunches. Such effects are usually not taken into account in standard multi-particle phase-space codes.

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MOPOW003

RF Phase Jitter Consideration in Bunch Compression

klystron, electron, linac, FEL

704

T.K. Charles, D.M. Paganin
Monash University, Faculty of Science, Clayton, Victoria, Australia
M.J. Boland, R.T. Dowd
SLSA, Clayton, Australia

Error propagation of RF phase jitter is analysed for various linac layout configurations and the sensitivity of the compression ratio due to RF phase jitter is analysed. Multiple sources of jitter have the opportunity to destructively interfere, and (perhaps counter intuitively) found to not add in quadrature. Results are compared to Elegant simulations.

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MOPOW004

Electron Trajectory Caustic Formation Resulting in Current Horns present in Bunch Compression

electron, FEL, linac, wakefield

708

T.K. Charles, D.M. Paganin
Monash University, Faculty of Science, Clayton, Victoria, Australia
M.J. Boland, R.T. Dowd
SLSA, Clayton, Australia

Current horns are ubiquitous in Free Electron Laser (FEL) bunch compression. In this paper, we analyse the formation of these current spikes and identify the cause as caustic formation in the electron trajectories. We also present a possible solution to avoid or mitigate the current horns from developing through using optical linearization.

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MOPOW009

Studies of Harmonic Lasing Self-seeded FEL at FLASH2

undulator, FEL, electron, radiation

725

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

A concept of the Harmonic Lasing Self-Seeded (HLSS) FEL was proposed in*,**. A gap-tunable undulator is divided into two parts such that the first part is tuned to a sub-harmonic of the second part. Harmonic lasing occurs in the exponential gain regime in the first part of the undulator, also the fundamental stays well below saturation. In the second part of the undulator the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is reduced by a significant factor depending on harmonic number but the saturation power is still as high as in the reference case of lasing at the fundamental in the whole undulator, i.e. the spectral brightness increases. Application of the post-saturation tapering would allow to generate higher peak power than in SASE mode due to an improved longitudinal coherence. We present feasibility study of the application of the HLSS FEL scheme at FLASH2 and show that it allows to achieve a higher power and a smaller bandwidth than in a standard SASE regime. First experimental tests are eventually discussed.
* E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 15 (2012) 080702
** E.A. Schneidmiller and M.V. Yurkov, "Harmonic Lasing Self-Seeded FEL", Proc. of FEL2013 Conf., New York, USA

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MOPOW011

Operation of Free Electron Laser FLASH Driven by Short Electron Pulses

radiation, electron, undulator, laser

732

V. Balandin, G. Brenner, C. Gerth, N. Golubeva, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov
DESY, Hamburg, Germany
E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Rönsch-Schulenburg, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

The program of low charge mode of operation is under development at free electron laser FLASH aiming in single mode radiation pulses. A short pulse photoinjector laser has been installed at FLASH allowing production of ultrashort electron pluses with moderate compression factor of the beam formation system. Here we present pilot results of free electron laser FLASH operating at the wavelength of 13.1 nm and driven by 70 pC electron bunches. Relevant theoretical analysis has been performed showing good agreement with experimental results.

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MOPOW027

Generation of Coherent Mode-locked Radiation in a Seeded Free Electron Laser

electron, radiation, FEL, laser

777

Z. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
D. Xiang
Shanghai Jiao Tong University, Shanghai, People's Republic of China

We present the promise of generating mode-locked multichromatic radiations in a seeded free electron laser based on high gain harmonic generation (HGHG). 3D start-to-end simulations have been carried out and analysis & comparisons have been made to have a research on the properties of each system. In these schemes, either the electron beam density or the seed laser intensity is modulated to produce a coherent radiation pulse train that yields multiple spectral lines in FEL output. Stable peak power at gigawatt level can be generated in the undulator finally.

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MOPOW029

The Soft X-ray Self-seeding System Design for SXFEL User Facility

undulator, FEL, electron, photon

785

K.Q. Zhang, T. Liu, D. Wang
SINAP, Shanghai, People's Republic of China
Y. Feng
SLAC, Menlo Park, California, USA

X-ray free electron laser driven by SASE probes the evolution of the new generation light source in high brightness, transverse coherence. However, since SASE achieves lasing from random shotnoise, Poor longitudinal coherence and relative wide bandwidth of SASE FEL limit the operation of many type experiments. Self-seeding as a promising scheme produces longitudinal coherence and even narrower bandwidth radiation by a monochromatic seeding instead of external seeding. The self-seeding system design based on the grating monochromator is carried out for SXFEL user facility across the photon energy from 800-1200 eV. The grating monochromator with a resolution power of 〖10〗^-4 can provide a monochromatic seeding pulse to the seeding undulator. The layout design and simulations of the scheme are presented. It is showing that the self-seeding system for SXFEL user facility is able to improve SASE FEL longitudinal coherence significantly.

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MOPOW036

Design Optimization of an X-band based FEL

linac, FEL, emittance, gun

793

A.A. Aksoy
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
A. Latina, J. Pfingstner, D. Schulte
CERN, Geneva, Switzerland
Z. Nergiz
Nigde University, Nigde, Turkey

A design effort for a new generation of compact, cost-effective, power-efficient FEL facilities, based on X-band technology, has been launched. High-frequency X-band acceleration implies strong wakefields, tight alignment and mechanical tolerances, and challenging stability issues. In this paper a design is proposed for the injector and the linacs, including the two bunch compressors. RF gun and injector simulations have been performed, successfully meeting the stringent requirements in terms of minimum projected emittance, sliced emittance and minimum bunch length. In the design of the linac and bunch compressors wakefield effects and misalignment have been taken into account. Start-to-end tracking simulations through the optimized lattice are presented and discussed.

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MOPOW037

Developments in the CLARA FEL Test Facility Accelerator Design and Simulations

linac, FEL, space-charge, undulator

797

P.H. Williams, D. Angal-Kalinin, A.D. Brynes, J.A. Clarke, F. Jackson, J.K. Jones, J.W. McKenzie, B.L. Militsyn, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.B. Appleby
UMAN, Manchester, United Kingdom
B. Kyle
University of Manchester, Manchester, United Kingdom

We present recent developments in the accelerator design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. In order to prioritise FEL schemes requiring the shortest electron bunches, the layout has changed significantly to enable compression at higher energy. Four proposed modes of operation are defined and tracked from cathode to FEL using ASTRA. Supplementing these baseline mode definitions with CSR-enabled codes (such as CSRTRACK) where appropriate is in progress. The FEL layout is re-optimised to include shorter undulators with delay chicanes between each radiator.

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MOPOW040

High Efficiency, High Brightness X-ray Free Electron Lasers via Fresh Bunch Self-Seeding

electron, undulator, extraction, photon

805

C. Emma, C. Pellegrini
UCLA, Los Angeles, USA
M.W. Guetg, A.A. Lutman, A. Marinelli, C. Pellegrini, J. Wu
SLAC, Menlo Park, California, USA

High efficiency, terawatt peak power X-ray Free Electron Lasers are a promising tool for enabling single molecule imaging and nonlinear science using X-rays. Increasing the efficiency of XFELs while achieving good longitudinal coherence can be achieved via self-seeding and undulator tapering. The efficiency of self-seeded XFELs is limited by two factors: the ratio of seed power to beam energy spread and the ratio of seed power to shot noise power. We present a method to overcome these limitations by producing a strong X-ray seed and amplifying it with a small energy spread beam. This is achieved by selectively suppressing lasing for part of the bunch in the SASE section. In this manner we can saturate with the seeding electrons and amplify the strong seed with 'fresh' electrons downstream of the monochromator. Simulations of this scenario are presented for two systems, an optimal superconducting undulator design and the LCLS. In the case of the LCLS we examine how betatron oscillations leading to selective suppression are induced by using the transverse wakefield of a parallel plate dechirper. We also discuss extending the selective suppression scheme to chirped electron bunches.

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MOPOY003

Study of Achieving Low Energy Beam by Energy Degradation and Direct Resonance Extraction in a Compact Ring

extraction, space-charge, resonance, synchrotron

850

G.R. Li, X.W. Wang, Z. Yang, H.J. Yao, Q. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China
X. Guan
Tsinghua University, Beijing, People's Republic of China

We have designed a compact proton synchrotron(7~230 MeV) for applications like proton therapy and space environment study. These applications may require slow extraction from 10~230 MeV. Traditionally, the low energy beam(10~70 MeV) is achieved by energy degradation from high energy beam which may cause beam lose and energy spread increase, because the beam quality may suffer from magnetic remanence, power ripple and strong space charge effects in low energy stage. To achieve high quality beam directly from resonance extraction, we study these effects by performing multi-particle simulation. Methods of improving beam quality are discussed.

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MOPOY010

Simulations and Measurements of Stopbands in the Fermilab Recycler

resonance, space-charge, proton, operation

864

R. Ainsworth, P. Adamson, K.J. Hazelwood, I. Kourbanis, E.G. Stern
Fermilab, Batavia, Illinois, USA

Fermilab has recently completed an upgrade to the complex with the goal of delivering 700 kW of beam power as 120 GeV protons to the NuMI target. A major part of boosting beam power is to use the Fermilab Recycler to stack protons. Simulations focusing on the betatron resonance stopbands are presented taking into account different effects such as intensity and chromaticity. Simulations are compared with measurements.

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MOPOY012

Space Charge Simulations in the Fermilab Recycler for PIP-II

space-charge, proton, booster, experiment

870

R. Ainsworth, P. Adamson, I. Kourbanis, E.G. Stern
Fermilab, Batavia, Illinois, USA

Proton Improvement Plan-II (PIP-II) is Fermilab's plan for providing powerful, high-intensity proton beams to the laboratory's experiments. Upgrades are foreseen for the recycler which will cope with bunches containing fifty percent more beam. Of particular concern is large space charge tune shifts caused by the intensity increase. Simulations performed using Synergia are detailed focusing on the space charge footprint.

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MOPOY013

Modeling Longitudinal Dynamics in the Fermilab Booster Synchrotron

booster, impedance, emittance, synchrotron

873

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

Funding: Work performed under U.S. Government contract DE-AC02-07CH11359
The PIP-II project will replace the existing 400 MeV linac with a new, CW-capable, 800 MeV superconducting one. With respect to current operations, a 50% increase in beam intensity in the rapid cycling Booster synchrotron is expected. Booster batches are combined in the Recycler ring; this process limits the allowed longitudinal emittance of the extracted Booster beam. To suppress eddy currents, the Booster has no beam pipe; magnets are evacuated, exposing the beam to core laminations and this has a substantial impact on the longitudinal impedance. Noticeable longitudinal emittance growth is already observed at transition crossing. Operation at higher intensity will likely necessitate mitigation measures. We describe systematic efforts to construct a predictive model for current operating conditions. A longitudinal only code including a laminated wall impedance model, space charge effects, and feedback loops is developed. Parameter validation is performed using detailed measurements of relevant beam, rf and control parameters. An attempt is made to benchmark the code at operationally favorable machine settings.

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MOPOY016

HSI RFQ Upgrade for the UNILAC Injection to FAIR

rfq, bunching, emittance, ion

877

C. Zhang, L. Groening, O.K. Kester, S. Mickat, H. Vormann
GSI, Darmstadt, Germany
M. Baschke, H. Podlech, U. Ratzinger, R. Tiede
IAP, Frankfurt am Main, Germany

As an injector to the future FAIR facility, the UNILAC accelerator is required to deliver ion beams with high intensities as well as good beam quality. The electrodes of the current HSI RFQ are exhausted and the current RFQ itself is assigned to be one bottle-neck for improving the brilliance performance of the whole linac. Based on the so-called NFSP (New Four-Section Procedure) method, a new RFQ electrode design has been developed and optimized for 20 emA, U⁴⁺ beams at the RFQ entrance. Since only the electrodes will be replaced, the RFQ length has been kept unchanged. Even with a lowered inter-vane voltage, the new RFQ design has achieved better beam performance compared to the previous design. This paper will focus on the performed study with respect to beam dynamics.

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MOPOY020

Prototype Design of a Newly Revised CW RFQ for the High Charge State Injector at GSI

rfq, operation, resonance, impedance

889

D. Koser, H. Podlech
IAP, Frankfurt am Main, Germany
P. Gerhard, L. Groening, O.K. Kester
GSI, Darmstadt, Germany

Within the scope of the FAIR project (Facility for Antiproton and Ion Research) at GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, the front end of the existing High Charge State Injector (HLI) is planned to be upgraded for cw operation. The required newly revised 4-Rod RFQ structure is currently being designed at the Institute for Applied Physics (IAP) of the Goethe University of Frankfurt. It will be operated with a 100 kW power amplifier at 108 MHz. At first instance a dedicated 4-stem prototype, which is based on the RFQ design for MYRRHA* and FRANZ**, is planned to be manufactured in order to validate the simulated RF performance, thermal behavior and mechanical characteristics in continuous operation. The RF simulations as well as basic thermal simulations are done using CST Studio Suite. In order to prevent oscillations of the electrodes mechanical eigenmodes are analyzed using ANSYS Multiphysics. In addition the ANSYS software allows more sophisticated simulations regarding the cooling capability by considering fluid dynamics in water cooling channels, thus providing a more detailed thermal analysis.
*C. Zhang, H. Podlech, New Reference Design of the European ADS RFQ Accelerator For MYRRHA, IPAC2014
**M. Heilmann et al., A Coupled RFQ-IH Cavity for the Neutron Source FRANZ, IPAC2013

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MOPOY027

Emittance Measurement with Wire Scanners at C-ADS Injector-I

emittance, rfq, beam-transport, background

910

H. Geng, C. Meng, Y.F. Sui, F. Yan, L. Yu, Y.L. Zhao
IHEP, Beijing, People's Republic of China

The transverse emittance at C-ADS injector-I has been measured by the wire scanners at the Medium Energy Beam Transport-I (MEBT1). We have studied the effect of different fitting methods for obtaining the beam sizes on the emittance result, the result will be presented in this paper. The validation study of the quad-scan method with the presence of space charge effect at 10 mA will also be shown, and finally the quad-scan results will be compared with the multi-wire results.

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MOPOY031

Emittance Measurement with Double-Slit Method in CADS Injector-I

emittance, solenoid, rfq, linac

922

C. Meng, H. Geng, Z. Xue, F. Yan, L. Yu, Y.L. Zhao
IHEP, Beijing, People's Republic of China

The C-ADS accelerator is a CW (Continuous-Wave) proton linac with 1.5 GeV in beam energy, 10 mA in beam current, and 15 MW in beam power. CADS Injector-I accelerator is a 10-mA 10-MeV CW proton linac, which uses a 3.2-MeV normal conducting 4-Vane RFQ and superconducting single-spoke cavities for accelerating. The 5MeV test stand of CADS accelerator Injector I is composed of an ion source, a LEBT, a 325MHz RFQ, a MEBT, a cryogenic module (CM1) of seven SC spoke cavities (β=0.12) , seven SC solenoids, seven cold BPMs and a beam dump. Emittance measurement is very important for the understanding of beam behavior and matching to the next accelerating section. Detailed emittance measurement with double-slit method after CM1 are presented in this paper.

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MOPOY032

Beam Twiss Measurement With Ws Including Space Charge Effect

experiment, space-charge, lattice, rfq

925

Y.L. Zhao, H. Geng, C. Meng, F. Yan
IHEP, Beijing, People's Republic of China

Wire Scanners (WS) are used to measure beam profile and calculate the transverse Twiss parameters at the entrance of MEBT1 in the CADS injector I test stand. As to data process, the traditional method with transfer map doesn't consider the space charge effect. But, as we know, space charge effect can't be neglected for high intensity accelerators. In this paper, optimization algorithm is used in beam emittance measurement.

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MOPOY033

Design Study on an Injector RFQ for Heavy Ion Accelerator Facility

rfq, cavity, ion, heavy-ion

928

W. Ma, Y. He, L. Lu, X.B. Xu, Z.L. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China

A Low Energy Accelerator Facility (LEAF) was launched as a pre-research facility for High Intensity heavy ion Accelerator Facility (HIAF). The LEAF consists of a 2-mA U³⁴⁺ electron cyclotron resonance (ECR) type ion source with 300-kV extraction voltage, a low energy beam transport (LEBT) line with a multi-harmonic buncher (MHB), a CW 81.25MHz radio frequency quad-rupole (RFQ) accelerator which could accelerate heavy ions from 14 keV/u up to 500 keV/u, a triplet magnet for medium energy beam transport and an experimental platform for nuclear physics. After describing the selected structure, an octagonal cavity with π-mode stabilizing loop (PISL) type structure was adopted and simulated. In this paper, the detailed electromagnetic design and ther-mal simulation of the LEAF-RFQ will be reported.

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MOPOY038

Studies for Tuning Algorithm of Superconducting Cavity Amplitude and Phase in the RAON Accelerator

cavity, linac, GUI, interface

932

H. Jin, J.-H. Jang
IBS, Daejeon, Republic of Korea

The RAON accelerator utilizes the low energy and high energy superconducting linacs for the acceleration of the stable ion beams and the rare isotope beams. The low energy superconducting linac is composed of the quarter-wave resonator (QWR) and the half-wave resonator (HWR) cavities, and the high energy superconducting linac consists of two kinds of single-spoke resonator (SSR) cavities. In the beam commissioning, the tuning of these superconducting cavities is a significant issue to achieve the targeted beam energy and to avoid the deterioration of the beam quality. In this paper, we will present the tuning program based on the phase scan tuning algorithm for the superconducting cavity amplitude and phase in the RAON accelerator and describe the simulation results.

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MOPOY041

Commissioning of New Proton and Light Ion Injector for Nuclotron-Nica

rfq, linac, ion, vacuum

941

S.M. Polozov, V.S. Dyubkov, M. Gusarova, T. Kulevoy, A.A. Martynov, A.S. Plastun, A.V. Samoshin
MEPhI, Moscow, Russia
V. Aleksandrov, A.V. Butenko, B.V. Golovenskiy, A. Govorov, V. Kobets, A.D. Kovalenko, V. Monchinsky, V.V. Seleznev, A.O. Sidorin, G.V. Trubnikov
JINR, Dubna, Moscow Region, Russia
V. Andreev, A.I. Balabin, S.V. Barabin, V.A. Koshelev, A.V. Kozlov, G. Kropachev, R.P. Kuibeda, T. Kulevoy, V.G. Kuzmichev, D.A. Liakin, A.Y. Orlov, A.S. Plastun, D.N. Selesnev, A. Sitnikov, Yu. Stasevich
ITEP, Moscow, Russia
A.P. Durkin
MRTI RAS, Moscow, Russia
K.A. Levterov
JINR/VBLHEP, Dubna, Moscow region, Russia
S.V. Vinogradov
MIPT, Dolgoprudniy, Moscow Region, Russia

The new accelerator complex Nuclotron-based Ion Collider fAcility (NICA) is now under development and construction at JINR. New complex is assumed to operate using two injectors: the Alvarez-type linac LU-20 as injector of light ions, polarized protons and deuterons and a new linac HILac of heavy ions. Now the modernization of LU-20 is also realized and old pulse DC injector is planning to replace by RFQ linac. New RFQ linac was developed and manufactured and is now under commissioning at Nuclotron injectors hall. New results of RFQ linac resonator testing and measurements, RF power load and linac testing with deuterium and carbon beam will discuss in this report.

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MOPOY042

The Perspective of Jinr Lu-20 Replacement by a Superconducting Linac

linac, proton, ion, cavity

944

S.M. Polozov, M. Gusarova, T. Kulevoy, M.V. Lalayan, A.V. Samoshin, S.E. Toporkov
MEPhI, Moscow, Russia
M.A. Baturitski
BSU, Minsk, Belarus
A.V. Butenko, V. Monchinsky, A.O. Sidorin, G.V. Trubnikov
JINR, Dubna, Moscow Region, Russia
G. Kropachev, T. Kulevoy
ITEP, Moscow, Russia
A.A. Marysheva, V.S. Petrakovsky, I.L. Pobol, A.I. Pokrovsky, S.V. Yurevich, A.Yu. Zhuravsky
Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus

The new accelerator complex Nuclotron-based Ion Collider fAcility (NICA) is now under development and construction at JINR. Existing Alvarez-type DTL linac LU-20 is now operates as injector of light ions, polarized protons and deuterons to Nuclotron for LHEP experimental program. It provides proton beam of 20 MeV energy and light ions of 5 MeV/u energy. In 2015 the cascade transformer 800 kV which is pre-accelerator of LU-20 had been replaced by the new RFQ linac (energy 155 keV for ions with Z/A<0.5). The proposal on Alvarez linac LU-20 upgrade by a superconducting light ion linac with energy up to 50 MeV is discussed in this report.

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MOPOY050

Beam Commissioning Plan of the FRIB Superconducting Linac

linac, cavity, operation, optics

961

Y. Zhang, C.P. Chu, Z.Q. He, M. Ikegami, S.M. Lidia, S.M. Lund, F. Marti, G. Shen, Y. Yamazaki, Q. Zhao
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The FRIB superconducting linac will deliver all heavy ion beams with energy above 200 MeV/u, and beam power on target up to 400 kW for generation of short lived isotopes. Beam commissioning is the first step to prepare and tune the superconducting linac for high power operation. A staged beam commissioning plan of the FRIB linac is developed, and complete beam tuning practices segment by segment through the entire linac are introduced, which include phase scan signature matching of the superconducting cavities, longitudinal beam matching, transverse matching with horizontal-vertical beam coupling, and beam optics corrections of achromatic and isochronous folding segments up to the second order for acceleration and transport of multi charge state beams.

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MOPOY051

Manufacturing and the LLRF Tests of the SANAEM RFQ

rfq, cavity, vacuum, LLRF

964

G. Turemen, Y. Akgun, A. Alacakir, A.S. Bolukdemir, I. Kilic, B. Yasatekin
TAEK - SANAEM, Ankara, Turkey
G. Unel
UCI, Irvine, California, USA
H. Yildiz
Istanbul University, Istanbul, Turkey

Funding: Turkish Atomic Energy Authority
Turkish Atomic Energy Authority is working on building an experimental proton beamline with local resources at the Saraykoy Nuclear Research and Training Center (SANAEM). Manufacturing of the radio frequency quadrupole (RFQ) was started after the beam dynamics and 3D electromagnetic simulation studies were performed. The vanes were machined with a three axis CNC machine. A CMM was used for the acceptance tests of the vanes and also for assembling. Production and assembly results were found acceptable for this cavity, the very first one developed in Turkey. Copper plating was performed by electroplating the aluminum vanes. The plated vanes were bolted and bonded with eight screws, eight pins and two different adhesives. A silver paste was used for RF sealing and a low vapor pressure epoxy was used for vacuum isolation. First LLRF tests of the RFQ were done with a bead-pull setup and a VNA. A N-type RF coupler and a pick-up were used for the LLRF tests. Phase shift method was used for the bead-pull tests. Cavity quality factor was measured with 3dB method for different RF sealing stages. This study summarizes the machining, assembling and the first LLRF tests of the SANAEM RFQ.

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MOPOY058

Removing Known SPS Intensity Limitations for High Luminosity LHC Goals

impedance, vacuum, emittance, shielding

989

E.N. Shaposhnikova, T. Argyropoulos, T. Bohl, P. Cruikshank, B. Goddard, T. Kaltenbacher, A. Lasheen, J. Perez Espinos, J. Repond, B. Salvant, C. Vollinger
CERN, Geneva, Switzerland

In preparation of the SPS as an LHC injector its impedance was significantly reduced in 1999 - 2000. A new SPS impedance reduction campaign is planned now for the High Luminosity (HL)-LHC project, which requires bunch intensities twice as high as the nominal one. One of the known intensity limitations is a longitudinal multi-bunch instability with a threshold 3 times below this operational intensity. The instability is presently cured using the 4th harmonic RF system and controlled emittance blow-up, but reaching the HL-LHC parameters cannot be assured without improving the machine impedance. Recently the impedance sources responsible for this instability were identified and implementation of their shielding and damping is foreseen during the next long shutdown (2019 - 2020) in synergy with two other important upgrades: amorphous carbon coating of (part of) the vacuum chamber against the e-cloud effect and rearrangement of the 200 MHz RF system. In this paper the strategy of impedance reduction is presented together with beam intensity achievable after its realisation. The potential effect of other proposals on remaining limitations is also considered.

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MOPOY060

Performance Analysis for the New g-2 Experiment at Fermilab

storage-ring, injection, experiment, dipole

996

D. Stratakis, M.E. Convery, C. Johnstone, J.A. Johnstone, J.P. Morgan, M.J. Syphers
Fermilab, Batavia, Illinois, USA
J.D. Crmkovic, W. Morse, V. Tishchenko
BNL, Upton, Long Island, New York, USA
N.S. Froemming
University of Washington, CENPA, Seattle, USA
M. Korostelev
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M. Korostelev
Lancaster University, Lancaster, United Kingdom

The new g-2 experiment at Fermilab aims to measure the muon anomalous magnetic moment to a precision of ±0.14 ppm ─ a fourfold improvement over the 0.54 ppm precision obtained in the g-2 BNL E821experiment. Achieving this goal requires the delivery of highly polarized 3.094 GeV/c muons with a narrow ±0.5% Δp/p acceptance to the g-2 storage ring. In this study, we describe a muon capture and transport scheme that should meet this requirement. First, we present the conceptual design of our proposed scheme wherein we describe its basic features. Then, we detail its performance numerically by simulating the pion production in the (g-2) production target, the muon collection by the downstream beamline optics as well as the beam polarization and spin-momentum correlation up to the storage ring. The sensitivity in performance of our proposed channel against key parameters such as magnet apertures and magnet positioning errors is analyzed

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TUOAB01

Optimization of the Dechirper for Electron Bunches of Arbitrary Longitudinal Shapes

wakefield, electron, controls, dipole

1054

J.M. Seok, M. Chung
UNIST, Ulsan, Republic of Korea
J.H. Han, J.H. Hong, H.-S. Kang
PAL, Pohang, Kyungbuk, Republic of Korea

Dechirper is a passive device composed of a vacuum chamber of two corrugated, metallic plates with an adjustable gap. By introducing a small offset in the dechirper with respect to the reference axis, one might generate transverse wakefields and use the dechirper as a deflector. Understanding the interactions between electron beams of various longitudinal shapes with the wakefields generated by the dechirper is important to assess the feasibility of the dechirper for use as a deflector. Recently, using a set of alpha-BBO crystals, shaping of laser pulses and electron bunches on the order of ps is tested at the Injector Test Facility (ITF) of Pohang Accelerator Laboratory (PAL). Furthermore, we have investigated propagation of electron bunches of arbitrary longitudinal shapes through the dechirper. In the numerical simulations, we observed that the arbitrary electron beams were successful deflected except for lethal beam shape problems. Hence, in this work, we study optimization of the dechirper for electron bunches of arbitrary longitudinal shapes, using analytical theory and numerical simulations with the ASTRA and ELEGANT codes.

Slides TUOAB01 [1.631 MB]

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TUOAB03

Transverse Coherent Instabilities in Storage Rings with Harmonic Cavities

synchrotron, radio-frequency, impedance, cavity

1061

F.J. Cullinan, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France
G. Skripka, P.F. Tavares
MAX IV Laboratory, Lund University, Lund, Sweden

Many current and future synchrotron light sources employ harmonic cavities to lengthen the electron bunches in order to reduce the emittance dilution caused by intrabeam scattering. In some cases, the harmonic cavities may be tuned to fulfill the flat potential condition. For this condition, a large increase in the threshold currents of transverse coupled-bunch instabilities has been predicted and recently, the physical content behind this stabilization has been better understood. With this in mind, an investigation is made into the effectiveness of harmonic cavities for different machines. Frequency domain computations employing Laclare's eigenvalue method have been used to investigate the influence of several machine parameters and the results are presented.

Slides TUOAB03 [14.037 MB]

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TUPMB005

Design and Fabrication of the Compact-Erl Magnets

quadrupole, sextupole, linac, electron

1111

A. Ueda, K. Endo, K. Harada, T. Kume, T. Miyajima, S. Nagahashi, N. Nakamura, M. Shimada
KEK, Ibaraki, Japan

The compact Energy Recovery Linac (cERL) was con-structed and operated at KEK. For the cERL we designed and fabricated the eight main bending magnets, fifty seven quadrupole magnets, four sextupole magnets and sixteen small bending magnets [1]. These magnets are used at 3 MeV (for low energy part) and 20 MeV (high energy part) beam energy now, but we designed them to be used maximum 10 MeV and 125 MeV beam energy for future upgrade of the cERL. The magnetic field analysis was done by 2D and 3D simulation code (OPERA) to design magnet shape. The main bending magnets and quadrupole magnets are made of electromagnetic steel sheet and the other magnets are made of electromagnetic soft iron. In this paper, we show the detail of the design-ing and fabricating work of those magnets.

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TUPMB011

Calculation and Analysis of the Magnetic Field of a Transverse Gradient Undulator

undulator, electron, FEL, laser

1130

J. Li, B. Du, Q.K. Jia, H.T. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

Transverse gradient undulator (TGU) is attracting more and more attentions, especially for the rapid progress of laser plasma accelerator techniques. The transverse gradient of TGU is usually given by an empirical formula simply derived from the empirical formula of a uniform-parameter undulator. In this paper, we numerically investigate the transverse magnetic field of TGUs using the RADIA code. Through many simulations for TGUs with different magnet structures, we have given the dependences of transverse gradient parameter on the cant angle, the undulator period and the average gap. Based on these results, when the cant angle is small and the rate of the gap and period is in the range of 0.4-0.6, the simulation results agree with the empirical formula well. But, with the growing of the cant angle, or with the growing of the deviation of the rate of the gap and period from the range of 0.4-0.6, the difference between the simulation results and the empirical formula becomes larger.

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TUPMB015

Compact Rare-Earth Permanent Magnet Material System for Industrial Electron Accelerators Irradiation Field Formation

electron, quadrupole, radiation, permanent-magnet

1139

D.S. Yurov, A.N. Ermakov, V.V. Khankin, N.V. Shvedunov, V.I. Shvedunov
M.V. Lomonosov Moscow State University (MSU), Skobeltsyn Institute of Nuclear Physics, Moscow, Russia

A compact system for industrial electron accelerators irradiation field formation is described. This system permits to get uniform distribution of electron beam current along the direction perpendicular to product movement with the width 50 - 100 cm. Its main element is a non-linear quadrupole lens, based on rare-earth permanent magnet material. This system can be used instead of an electromagnet of the conventional beam scanning systems, making much more comfortable conditions for products irradiation. Operation principles, results of calculations and test results of the system for CW 1 MeV and pulse 10 MeV electron linear accelerators are described.

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TUPMB048

Compensation of Beam Induced Effects in LHC Cryogenic Systems

cryogenics, controls, electron, injection

1205

B. Bradu, E. Blanco Viñuela, G. Ferlin, B. Fernández Adiego, G. Iadarola, P. Plutecki, E. Rogez, A. Tovar González
CERN, Geneva, Switzerland

This paper presents the different control strategies deployed in the LHC cryogenic system in order to compensate the beam induced effects in real-time. LHC beam is inducing important heat loads along the 27 km of beam screens due to synchrotron radiations, image current and electron clouds. These dynamic heat loads disturb significantly the cryogenic plants and automatic compensations are mandatory to operate the LHC at full energy. The LHC beam screens must be maintained in an acceptable temperature range around 20 K to ensure a good beam vacuum, especially during beam injections and energy ramping where the dynamic responses of cryogenic systems cannot be managed with conventional feedback control techniques. Consequently, several control strategies such as feed-forward compensation have been developed and deployed successfully on the machine during 2015 where the beam induced heat loads are forecast in real-time to anticipate their future effects on cryogenic systems. All these developments have been first entirely modeled and simulated dynamically to be validated, allowing then a smooth deployment during the LHC operation.

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TUPMB052

High Intensity Beam Test of Low Z Materials for the Upgrade of SPS-to-LHC Transfer Line Collimators and LHC Injection Absorbers

experiment, injection, proton, radiation

1218

F.L. Maciariello, O. Aberle, M.E.J. Butcher, M. Calviani, R. Folch, V. Kain, K. Karagiannis, I. Lamas Garcia, A. Lechner, F.-X. Nuiry, G.E. Steele, J.A. Uythoven
CERN, Geneva, Switzerland

In the framework of the LHC Injector Upgrade (LIU) and High-Luminosity LHC (HL-LHC) project, the collimators in the SPS-to LHC transfer lines will undergo important modifications. The changes to these collimators will allow them to cope with beam brightness and intensity levels much increased with respect to their original design parameters: nominal and ultimate LHC. The necessity for replacement of the current materials will need to be confirmed by a test in the High Radiation to Materials (HRM) facility at CERN. This test will involve low Z materials (such as Graphite and 3-D Carbon/Carbon composite), and will recreate the worst case scenario those materials could see when directly impacted by High luminosity LHC (HL-LHC) or Batch Compression Merging and Splitting (BCMS) beams. Thermo-structural simulations used for the material studies and research, the experiment preparation phase, the experiment itself, pre irradiation analysis (including ultrasound and metrology tests on the target materials), the results and their correlation with numerical simulations will be presented.

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TUPMR004

Simulations of High Current NuMI Magnetic Horn Striplines at FNAL

proton, experiment, target, focusing

1230

T. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
J. Hylen, R.M. Zwaska
Fermilab, Batavia, Illinois, USA

Both the NuMI (Neutrinos and the Main Injector) beam line, that has been providing intense neutrino beams for several Fermilab experiments (MINOS, MINERVA, NOVA), and the newly proposed LBNF (Long Baseline Neutrino Facility) beam line which plans to produce the highest power neutrino beam in the world for DUNE (the Deep Underground Neutrino Experiment) need pulsed magnetic horns to focus the mesons which decay to produce the neutrinos. The high-current horn and stripline design has been evolving as NuMI reconfigures for higher beam power and to meet the needs of the LBNF design. The CSU particle accelerator group has aided the neutrino physics experiments at Fermilab by producing EM simulations of magnetic horns and the required high-current striplines. In this paper, we present calculations, using the Poisson and ANSYS Maxwell 3D codes, of the EM interaction of the stripline plates of the NuMI horns at critical stress points. In addition, we give the electrical simulation results using the ANSYS Electric code. These results are being used to support the development of evolving horn stripline designs to handle increased electrical current and higher beam power for NuMI upgrades and for LBNF

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TUPMR008

Simulation of Ion Beam under Coherent Electron Cooling

ion, electron, kicker, FEL

1243

G. Wang, M. Blaskiewicz, V. Litvinenko
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The proof of coherent electron cooling (CeC) principle experiment is currently under commissioning and it is essential to have the tools to predict the influences of cooling electrons on a circulating ion bunch. Recently, we have developed a simulation code to track the evolution of an ion bunch under the influences of both CeC and Intra-beam scattering (IBS). In this paper, we will first show the results of benchmarking the code with numerical solutions of Fokker-Planck equation and then present the simulation results for the proof of CeC principle experiment.

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TUPMR009

Analytical Studies of Ion Beam Evolution under Coherent Electron Cooling

ion, electron, synchrotron, scattering

1247

G. Wang, M. Blaskiewicz, V. Litvinenko
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the presence of coherent electron cooling (CeC), the evolution of the longitudinal profile of a circulating ion bunch can be described by the 1-D Fokker-Planck equation. We show that, in the absence of diffusion, the 1-D equation can be solved analytically for certain dependence of cooling force on the synchrotron amplitude. For more general cases, we solved the 1-D Fokker-Planck equation numerically and the numerical solutions have been used to benchmark our simulation code as well as providing fast estimations of the cooling effects.

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TUPMR011

Development of Optimized RF Cavity in 10 MeV Cyclotron

network, cyclotron, cavity, resonance

1250

M. Mohamadian, H. Afarideh, M. Salehi
AUT, Tehran, Iran
J.-S. Chai, M. Ghergherehchi
SKKU, Suwon, Republic of Korea

Cyclotron cavity modelled by an artificial neural net-work, which is trained by our optimized algorithm. The training samples are obtained from simulation results, which are done by MWS CST software for some defined situation and parameters, and also with the conventional BP algorithm. It is shown that the optimized FFN can estimate the cyclotron model parameters with acceptable outputs. Hence, the neural network trained by this algorithm represents the proper estimation and acceptable ability to our structure modelling. The cyclotron cavity parameter modelling illustrate that the neural network trained by this algorithm could be the acceptable method to design parameters.

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TUPMR015

Cooling and Heat Transfer of the IRANCYC-10 Transmission Line

impedance, cyclotron, factory, cavity

1259

S. Sabounchi, H. Afarideh, M. Mohamadian, M. Salehi
AUT, Tehran, Iran
J.-S. Chai, M. Ghergherehchi
SKKU, Suwon, Republic of Korea

Heat transfer study for designing RF transmission line in cyclotrons is crucial. Because of enormous amount of surface current on RF transmission line, despite high conductivity of copper, significant amount of heat is being generated, which is enough for altering characteristic impedance and other desirable parameters for transmission line. So, effective cooling system which is nourished by central chiller system is essential. For design of cooling system in RF transmission line suitable mass flow, appropriate geometry and confined temperatures are prominent in order to avoid eroding and impedance changing. In this paper an attempt has been done for accurate analyzing and simulating of heat transfer phenomenon for the 10MeV cyclotron (IRANCYC-10 ) which is under construction at AmirKabir University of Technology. By using Ansys CFX simulation software, the optimum cooling line geometry and mass flow rate of 90 gr/s for cooling water, has been resulted.

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TUPMR016

Research and Development of a Compact Superconducting Cyclotron SC200 for Proton Therapy

cyclotron, proton, cavity, extraction

1262

G.A. Karamysheva, S. Gurskiy, O. Karamyshev, S.A. Kostromin, N.A. Morozov, E.V. Samsonov, G. Shirkov
JINR, Dubna, Moscow Region, Russia
Y.F. Bi, G. Chen, K.Z. Ding, Y. Song
ASIPP, Hefei, People's Republic of China

According to the agreement between the Institute of Plasma Physics (IPP) of the Chinese Academy of Sciences in Hefei (China) and Joint Institute for Nuclear Research, Dubna, (Russia), the development of a superconducting isochronous cyclotron for proton therapy SC200 is started. The cyclotron will provide acceleration of protons up to 200 MeV with maximum beam current of 1 μA. We plan to manufacture in China two cyclotrons: one will operate in Hefei cyclotron medical center the other will replace Phasotron in Medico-technical Center JINR Dubna and will be used for further research and development of cancer therapy by protons. Now we present main parameters of cyclotron and simulation results of magnetic, accelerating and extraction systems.

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TUPMR017

Computer Modeling of Magnet for SC200 Superconducting Cyclotron

cyclotron, extraction, proton, focusing

1265

N.A. Morozov, O. Karamyshev, G.A. Karamysheva, E.V. Samsonov, G. Shirkov
JINR, Dubna, Moscow Region, Russia
Y.F. Bi, G. Chen, K.Z. Ding, Sh. Du, H. Feng, J. Ge, J. Li, X. Liu, Y. Song, J. Zheng
ASIPP, Hefei, People's Republic of China

The superconducting cyclotron SC200 for proton therapy is designing by ASIPP (Hefei, China) and JINR (Dubna, Russia) will be able to accelerate protons to the energy 200 MeV with the maximum beam current of 1 mkA. By computer simulation with 3D codes the cyclotron magnet principal parameters were estimated (pole radius 0.62 m, outer diameter 2.2 m, valley depth 0.3 m, height 1.22 m, weight ~30 t). The required isochronous magnetic field is shaped with accuracy some mT. Four fold symmetry and spiralized sectors with minimal gap 4 mm at extraction provide the stable beam acceleration till 10 mm from the pole edge.

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TUPMR018

Beam Tracking Simulation for SC200 Superconducting Cyclotron

cyclotron, extraction, acceleration, resonance

1268

O. Karamyshev
JINR/DLNP, Dubna, Moscow region, Russia
Y.F. Bi, G. Chen, K.Z. Ding, Y. Song
ASIPP, Hefei, People's Republic of China
G.A. Karamysheva, N.A. Morozov, E.V. Samsonov, G. Shirkov, S.G. Shirkov
JINR, Dubna, Moscow Region, Russia

The SC200 superconducting cyclotron for hadron therapy is under development by collaboration of ASIPP (Hefei, China) and JINR (Dubna, Russia). The accelerator will provide 200 MeV proton beam with maximum current of 1μA in 2017-2018. The cyclotron is very compact and light, the estimate total weight is about 30 tons and extraction radius is 60 cm. We have performed simulations of all systems of the SC200 cyclotron and specified the main parameters of the accelerator. Average magnetic field of the cyclotron is up to 3.5 T and the particle revolution frequency is about 45 MHz, these parameters increases the requirements for accuracy of the beam dynamics studies. We have designed and performed beam tracking starting from the ion source. Codes and methods used for the beam tracking are presented.

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TUPMR019

Measurements of the Beam Phase Response to Correcting Magnetic Fields in PSI Cyclotrons

cyclotron, diagnostics, proton, operation

1271

A.S. Parfenova, C. Baumgarten, J.M. Humbel, A.C. Mezger
PSI, Villigen PSI, Switzerland
A.V. Petrenko
CERN, Geneva, Switzerland

The cyclotron-based proton accelerator facility (HIPA) at PSI is presently operated at 1.3-1.4 MW beam power at a kinetic energy of 590 MeV/u to drive the neutron spallation source SINQ and for production of pion and muon beams. Over the years HIPA facility has developed towards increase of the delivered beam current and beam power (0.1 mA in 1974 till 2.2 mA in 2010). During the last few years several upgrades of the Ring cyclotron field correction and beam phase monitoring systems were made. RF voltage was also increased. In order to test the performance of the upgraded system the phase response measurements were carried out.

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TUPMR020

In-depth Analysis and Optimization of the European Spallation Source Front End Lattice

rfq, solenoid, space-charge, emittance

1274

Y.I. Levinsen, M. Eshraqi
ESS, Lund, Sweden
L. Celona, L. Neri
INFN/LNS, Catania, Italy

The European Spallation Source front end will deliver a 62.5 mA beam current of 2.8 ms duration at 352 MHz to the downstream linac, which in turn will produce a 5 MW proton beam onto the target. Such unprecedented beam power requires a high quality beam with accurate and stable beam parameters in order to assure low beam losses and safe transport through the linac. In this paper we present advanced tuning methods for the low energy beam transport and the radio frequency quadrupole.

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TUPMR026

First Experience of Applying Loco for Optics at Cosy

quadrupole, optics, storage-ring, ion

1294

D. Ji
IHEP, Beijing, People's Republic of China
M. Bai, Y. Dutheil, F. Hinder, B. Lorentz, M. Simon, C. Weidemann
FZJ, Jülich, Germany

COSY is a cooler synchrotron designed for internal target hadron physics experiments, equipped with both electron cooling system and stochastic cooling system. During the past couple of years, COSY has been evolved into an ideal test facility for accelerator technology development as well as detector development for the Facility of Anti-proton and Ion Research at Darmstadt (FAIR). In addition, COSY has been the test ground for exploring the feasibility of a storage ring based Electric Dipole Moment (EDM) measurement. The proposed precursor experiment of a direct measurement of the EDM of the deuteron at COSY using an RF wien filter by the Jülich Electric Dipole moment Investigation (JEDI) requests significant improvement of beam based measurements as well as beam control. In this paper, first results of measured linear optics based on AT-LOCO are reported. Simulation studies are also discussed.

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TUPMR028

Spin Correlations Study for the New g-2 Experiment at Fermilab

experiment, storage-ring, injection, quadrupole

1301

D. Stratakis, J.D. Crnkovic, W. Morse, V. Tishchenko
BNL, Upton, Long Island, New York, USA

The muon g-2 experiment executed at Brookhaven concluded in 2001 and measured a discrepancy of more than three standard deviations compared to the Standard Model (SM) calculation. A new initiative at Fermilab is under construction to improve the experimental accuracy four-fold. Achieving this goal, however, requires the delivery of highly polarized 3.094 GeV/c muons with a narrow ±0.5% Δp/p acceptance to the g-2 storage ring. In this study, we examine systematic errors that can arise from correlations between muon spin and transverse coordinates for the new g-2 experiment. To achieve this goal we perform end-to-end spin tracking simulations from the production target up to the ring injection point and compare our findings against the results from the Brookhaven experiment. We detail similarities and differences.

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TUPMR036

Extraction Commissioning for MedAustron Proton Operation

extraction, synchrotron, resonance, sextupole

1327

T.K.D. Kulenkampff, A. Garonna, M. Kronberger, C. Kurfürst, S. Nowak, F. Osmić, L.C. Penescu, M.T.F. Pivi, C. Schmitzer, P. Urschütz, A. Wastl
EBG MedAustron, Wr. Neustadt, Austria

MedAustron is a synchrotron based ion beam therapy center for proton (62-250 MeV) and carbon ion (120-400 MeV/n) treatments. The MedAustron synchrotron uses a betatron core driven slow extraction scheme based on a third order resonance. The commissioning of the extraction from the synchrotron involved the setup of the correct orbit and optics at flattop. In order to maximize the momentum spread before extraction and optimize spill structure the RF system enforces a so called RF-phase jump to the unstable phase. Different scenarios were simulated using MADX-PTC [1] in combination with Python to overcome the static nature of PTC. Simulations have shown that the initial phase of the beam and a finite time to jump to the unstable fix point have a strong impact on the performance. Using a high frequency intensity monitor in the extraction channel (QIM), the spill structure was analysed and used for optimization. Simulation and measurements of the procedure are presented.

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TUPMR041

Design of the Low Energy Beam Transport Line for Xi‘an Proton Application Facility

rfq, ion, solenoid, ion-source

1343

R. Ruo, L. Du, T. Du, X. Guan, C.-X. Tang, R. Tang, X.W. Wang, Q.Z. Xing, H.Y. Zhang, Q.Z. Zhang
TUB, Beijing, People's Republic of China
W.Q. Guan, Y. He, J. Li
NUCTECH, Beijing, People's Republic of China

Xi‘an Proton Application Facility (XiPAF) is a new proton project which is being constructed for single-event-effect experiments. It can provide proton beam with the maximum energy of 200 MeV. The accelerator facility of XiPAF mainly contains a 7 MeV H⁻ linac injector and a proton synchrotron accelerator. The 7 MeV H⁻ linac injector is composed of an ECR ion source, a Low Energy Beam Transport line (LEBT), a Radio Frequency Quadrupole accelerator (RFQ) and a Drift Tube Linac (DTL). The 50 keV 10 mA H⁻ beam (pulse width 1ms) extracted from the ion source is expected to be symmetric with the Twiss parameters alpha=0 and β=0.065 mm/mrad. The RMS normalized emittance is required to be less than 0.2 π mm·mrad. With an adjustable collimator and an electric chopper in the 1.7 m-long LEBT, the beam pulse width of 10~40μs and peak current of 6 mA can be obtained. The H⁻ beam is matched into the downstream RFQ accelerator with alpha=1.051 and β=0.0494 mm/mrad. This paper shows the detailed design process of the LEBT and simulation result with the TRACEWIN code.

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TUPMR042

Transverse Profile Expansion and Homogenization for the Beamline of XIPAF

target, proton, experiment, optics

1346

Z. Yang, C.T. Du, X. Guan, W. Wang, X.W. Wang, H.J. Yao, S.X. Zheng
TUB, Beijing, People's Republic of China

For the Xi'an 200 MeV Proton Application Facility (XiPAF), one important thing is to produce more homog-enous beam profile at the target to fulfill the requirements of the beam application. Here the beam line is designed to meet the requirement of beam expansion and homogenization, and the step-like field magnets are employed for the beam spot homogenization. The simulations results including space charge effects and errors show that the beam line can meet the requirements well at the different energies (from 10 MeV to 230 MeV) and different beam spot size (from 20mm to 200mm).

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TUPMR049

Feasibility Study of the PS Injection for 2 GeV LIU Beams with an Upgraded KFA-45 Injection Kicker System Operating in Short Circuit Mode

injection, kicker, flattop, operation

1363

T. Kramer, W. Bartmann, J.C.C.M. Borburgh, L. Ducimetière, L.M.C. Feliciano, A. Ferrero Colomo, B. Goddard, L. Sermeus
CERN, Geneva, Switzerland

Under the scope of the LIU project the CERN PS Booster to PS beam transfer will be modified to match the requirements for the future 2 GeV beams. This paper describes the evaluation of the proposed upgrade of the PS injection kicker. Different schemes of an injection for LIU beams into the PS have been outlined in the past already under the aspect of individual transfer kicker rise and fall time performances. Homogeneous rise and fall time requirements in the whole PSB to PS transfer chain have been established which allowed to consider an upgrade option of the present injection kicker system operated in short circuit mode. The challenging pulse quality constraints require an improvement of the flat top and post pulse ripples. Both operation modes, terminated and short circuit mode are analysed and analogue circuit simulations for the present and upgraded system are outlined. Recent measurements on the installed kickers are presented and analysed together with the simulation data. First measurements verifying the performance of upgrade options have been taken during the last end of the year stop. The paper concludes with an upgrade plan and a brief overview of implementation risks.

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TUPMR050

Upgrades to the SPS-to-LHC Transfer Line Beam Stoppers for the LHC High-Luminosity Era

extraction, proton, kicker, brightness

1367

V. Kain, R. Esposito, M.A. Fraser, B. Goddard, M. Meddahi, A. Perillo Marcone, G.E. Steele, F.M. Velotti
CERN, Geneva, Switzerland

Each of the 3 km long transfer lines between the SPS and the LHC is equipped with two beam stoppers (TEDs), one at the beginning of the line and one close to the LHC injection point, which need to absorb the full transferred beam. The beam stoppers are used for setting up the SPS extractions and transfer lines with beam without having to inject into the LHC. Energy deposition and thermo-mechanical simulations have, however, shown that the TEDs will not be robust enough to safely absorb the high intensity beams foreseen for the high-luminosity LHC era. This paper will summarize the simulation results and limitations for upgrading the beam stoppers. An outline of the hardware upgrade strategy for the TEDs together with modifications to the SPS extraction interlock system to enforce intensity limitations for beam on the beam stoppers will be given.

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TUPMR054

Simulation of the FCC-hh Collimation System

collimation, betatron, proton, insertion

1381

J. Molson, P. Bambade, S. Chancé, A. Faus-Golfe
LAL, Orsay, France

Funding: Funding from the European Union's Horizon 2020 research and innovation programme under grant No 654305. Funding also from ANR-11-IDEX-0003-02.
The proposed CERN FCC-hh proton-proton collider will operate at unprecedented per-particle (50 TeV) and total stored beam energies (8.4 GJ). These high energies create the requirement for an efficient collimation system in order to protect the accelerator components and experiments. In order to verify the performance of proposed collimation system designs, loss map simulations have been performed using the code Merlin. Results for the current baseline layout are presented for both betatron and off-momentum loss maps.

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TUPMR060

Improvement of 18 MeV Cyclotron Magnet Design by TOSCA Code

cyclotron, resonance, betatron, factory

1397

N. Rahimpour Kalkhoran, H. Afarideh, R. Solhju
AUT, Tehran, Iran
J.-S. Chai, M. Ghergherehchi
SKKU, Suwon, Republic of Korea

According to increasing need to cyclotrons in the world, designing and manufacturing of these machines are considered. Therefore designing of 18 MeV cyclotron magnet has begun at Amirkabir University Of Technology. Magnet is one of the most important parts of the cyclotron, so in designing of magnet, all other components of cyclotron which influence on magnet, should be considered. Since the achievable energy for particle is determined 18MeV, designed magnet has AVF structure. TOSCA (Opera-3D) code was selected for simulation and analysis. First of all, theoretical calculations and estimations were done and magnetic field data according to radius were achieved, after that, simulation with initial estimations and a simple model of magnet was begun and optimization process continued until magnetic field results from the simulation coincided with the theoretical one. Different shimmings were used for better coincidence. Some results contains magnetic field on middle plane and betatron oscillations were checked. Also working points of the cyclotron with resonance regions were checked. According to use reliable mesh, the accuracy of simulation results is sufficient high.

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TUPMW006

Power Deposition in LHC Magnets Due to Bound-Free Pair Production in the Experimental Insertions

ion, dipole, luminosity, heavy-ion

1418

C. Bahamonde Castro, B. Auchmann, M.I. Besana, K. Brodzinski, R. Bruce, F. Cerutti, J.M. Jowett, A. Lechner, T. Mertens, V. Parma, S. Redaelli, M. Schaumann, N.V. Shetty, E. Skordis, G.E. Steele, R. van Weelderen
CERN, Geneva, Switzerland

The peak luminosity achieved during Pb-Pb collisions in the LHC in 2015 (3x1027cm^-2s⁻¹) well exceeded the design luminosity and is anticipated to increase by another factor 2 after the next Long Shutdown (2019- 2020). A significant fraction of the power dissipated in ultra-peripheral Pb-Pb collisions is carried by ions from bound-free pair production, which are lost in the dispersion suppressors adjacent to the experimental insertions. At higher luminosities, these ions risk to quench superconducting magnets and might limit their operation due to the dynamic heat load that needs to be evacuated by the cryogenic system. In this paper, we estimate the power deposition in superconducting coils and the magnet cold mass and we quantify the achievable reduction by deviating losses to less sensitive locations or by installing collimators at strategic positions. The second option is considered for the dispersion suppressor next to the ALICE insertion, where a selective displacement of losses to a magnet-free region is not possible.

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TUPMW009

Simulation of Head-on Beam-Beam Limitations in Future High Energy Colliders

emittance, synchrotron, collider, radiation

1430

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

The Future Circular Hadron Collider (FCC-hh) project calls for studies in a new regime of beam-beam interactions. While the emittance damping due to synchrotron radiation is still slower than in past or existing lepton colliders, it is significantly larger than in other hadron colliders. The slow reduction of the emittance is profitable for higher luminosity in term of transverse beam size at the interaction points and also to mitigate long-range beam-beam effects, potentially allowing for a reduction of the crossing angle between the beams during the operation. In such conditions, the strength of head-on beam-beam interactions increases, potentially limiting the beam brightness. 4D weak-strong and strong-strong simulations are performed in order to assess these limitations.

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TUPMW011

Current Status of Instability Threshold Measurements in the LHC at 6.5 TeV

octupole, damping, impedance, electron

1434

L.R. Carver, J. Barranco, N. Biancacci, X. Buffat, W. Höfle, G. Kotzian, T. Lefèvre, T.E. Levens, E. Métral, T. Pieloni, B. Salvant, C. Tambasco
CERN, Geneva, Switzerland
N. Wang
IHEP, Beijing, People's Republic of China
M. Zobov
INFN/LNF, Frascati (Roma), Italy

Throughout 2015, many measurements of the minimum stabilizing octupole current required to prevent coherent transverse instabilities have been performed. These measurements allow the LHC impedance model at flat top to be verified and give good indicators of future performance and limitations. The results are summarized here, and compared to predictions from the simulation code DELPHI.

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TUPMW015

Symplectic Tracking of Multi-Isotopic Heavy-Ion Beams in SixTrack

ion, heavy-ion, dipole, quadrupole

1450

P.D. Hermes, R. Bruce, R. De Maria
CERN, Geneva, Switzerland

Funding: Work suppported by the Wolfgang Gentner Programme of the German BMBF
The software SixTrack provides symplectic proton tracking over a large number of turns. The code is used for the tracking of beam halo particles and the simulation of their interaction with the collimators to study the efficiency of the LHC collimation system. Tracking simulations for heavy-ion beams require taking into account the mass to charge ratio of each particle because heavy ions can be subject to fragmentation at their passage through the collimators. In this paper we present the derivation of a Hamiltonian for multi-isotopic heavy-ion beams and symplectic tracking maps derived from it. The resulting tracking maps were implemented in the tracking software SixTrack. With this modification, SixTrack can be used to natively track heavy-ion beams of multiple isotopes through a magnetic accelerator lattice.

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TUPMW016

Effect of the LHC Beam Screen Baffle on the Electron Cloud Buildup

electron, shielding, proton, dipole

1454

A. Romano, G. Iadarola, K.S.B. Li, G. Rumolo
CERN, Geneva, Switzerland

Funding: Research supported by the High Luminosity LHC project
Electron Cloud (EC) has been identified as one of the major intensity-limiting factors in the CERN Large Hadron Collider (LHC). Due to the EC, an additional heat load is deposited on the perforated LHC beam screen, for which only a small cooling capacity is available. In order to preserve the superconducting state of the magnets, pumping slots shields were added on the outer side of the beam screens. In the framework of the design of the beam screens of the new HL-LHC triplets, the impact of these shields on the multipacting process was studied with macroparticle simulations. For this purpose multiple new features had to be introduced in the PyECLOUD code. This contribution will describe the implemented simulation model and summarize the outcome of this study.

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TUPMW017

Electron Cloud Observations during LHC Operation with 25 ns Beams

electron, operation, injection, cryogenics

1458

K.S.B. Li, H. Bartosik, G. Iadarola, L. Mether, A. Romano, G. Rumolo, M. Schenk
CERN, Geneva, Switzerland

While during the Run 1 (2010-2012) of the Large Hadron Collider (LHC) most of the integrated luminosity was produced with 50 ns bunch spacing, for the Run 2 start-up (2015) it was decided to move to the nominal bunch spacing of 25 ns. As expected, with this beam configuration strong electron cloud effects were observed in the machine, which had to be mitigated with dedicated 'scrubbing' periods at injection energy. This enabled to start the operation with 25 ns beams at 6.5 TeV, but e-cloud effects continued to pose challenges while gradually increasing the number of circulating bunch trains. This contribution will review the encountered limitations and the mitigation measures that where put in place and will discuss possible strategies for further performance gain.

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TUPMW019

First Evaluation of Dynamic Aperture at Injection for FCC-hh

dipole, injection, dynamic-aperture, target

1466

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

Funding: This Research and Innovation Action project submitted to call H2020-INFRADEV-1-2014-1 receives funding from the European Union's H2020 Framework Programme under grant agreement no. 654305.
In the hadron machine option, proposed in the context of the Future Circular Colliders (FCC) study, the dipole field quality is expected to play an important role, as in the LHC. A preliminary evaluation of the field quality of dipoles, based on the Nb3Sn technology, has been provided by the magnet group. The effect of these field imperfections on the dynamic aperture, using the present lattice design, is presented and first tolerances on the main multipole components are evaluated.

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TUPMW025

Machine Protection from Fast Crab Cavity Failures in the High Luminosity LHC

cavity, collimation, proton, luminosity

1485

A. Santamaría García, R. Bruce, H. Burkhardt, F. Cerutti, R. Kwee-Hinzmann, A. Lechner, K.N. Sjobak, A. Tsinganis
CERN, Geneva, Switzerland
R. Kwee-Hinzmann
Royal Holloway, University of London, Surrey, United Kingdom

The time constant of a crab cavity (CC) failure can be faster than the reaction time of the active protection system. In such a scenario, the beams cannot be immediately extracted, making the the protection of the machine rely on the passive protection devices. At the same time, the energy stored in the High Luminosity (HL) LHC beams will be doubled with respect to the LHC to more than 700 MJ, which increases the risk of damaging the machine and the experiments in a failure scenario. In this study we estimate the impact that different CC failures have on the collimation system. We also give a first quantitative estimate of the effect of these failures on the elements near the experiments based on FLUKA simulations, using an updated HL-LHC baseline.

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TUPMW028

Bound-Free Pair Production in LHC Pb-Pb Operation at 6.37 Z TeV per Beam

luminosity, experiment, ion, dipole

1497

J.M. Jowett, B. Auchmann, C. Bahamonde Castro, M.K. Kalliokoski, A. Lechner, T. Mertens, M. Schaumann, C. Xu
CERN, Geneva, Switzerland

In the 2015 Pb-Pb collision run of the LHC, the power of the secondary beams emitted from the interaction point by the bound-free pair production process reached new levels while the propensity of the bending magnets to quench is higher at the new magnetic field levels. This beam power is about 70 times greater than that contained in the luminosity debris and is focussed on a specific location. As long foreseen, orbit bumps were introduced in the dispersion suppressors around the highest luminosity experiments to mitigate the risk by displacing and spreading out these losses. An experiment designed to induce quenches and determine the quench levels and luminosity limit was carried out to assess the need for special collimators to intercept these secondary beams.

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TUPMW035

Performance and Operational Aspects of HL-LHC Scenarios

luminosity, optics, emittance, electron

1516

L.E. Medina Medrano
DCI-UG, León, Mexico
R. Tomás
CERN, Geneva, Switzerland

Funding: Research supported by the High Luminosity LHC project. Work supported by the Beam Project (CONACYT, Mexico).
Several alternatives to the present HL-LHC baseline configuration have been proposed, aiming either to improve the potential performance, reduce its risks, or to provide options for addressing possible limitations or changes in its parameters. In this paper we review and compare the performance of the HL-LHC baseline and the main alternatives with the latest parameters set. The results are obtained using refined simulations of the evolution of the luminosity with β^*-levelling, for which new criteria have been introduced, such as improved calculation of the intrabeam scattering and the addition of penalty steps to take into account the necessary time to move between consecutive optics during the process. The features of the set of optics are discussed for the nominal baseline.

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TUPMW040

Beam-beam Simulation for the 2015 RHIC Proton Run with Electron Lenses

proton, dynamic-aperture, electron, lattice

1533

Y. Luo, W. Fischer, X. Gu, G. Robert-Demolaize, V. Schoefer
BNL, Upton, Long Island, New York, USA
S.M. White
ESRF, Grenoble, France

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron lenses were used for head-on beam-beam compensation for the first time in the 2015 Relativistic Heavy Ion Collider (RHIC) 100~GeV polarized proton run. Lattices with the achromatic telescopic squeeze (ATS) scheme of β^* are adopted to improve the off-momentum dynamic aperture. The phase advances between the electron lenses to one of the two collisional points are set to kπ to minimize the beam-beam resonance driving terms. In this article, we present the results from weak-strong and strong-strong beam-beam simulations with head-on beam-beam compensations for these lattices. Simulations are also carried out aiming to explain the observations from operation.

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TUPMY004

The MICE Demonstration of Muon Ionization Cooling

emittance, lattice, betatron, experiment

1547

J.-B. Lagrange, C. Hunt, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
V.C. Palladino
INFN-Napoli, Napoli, Italy
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

Funding: STFC, DOE, NSF, INFN, CHIPP AND MORE
Muon beams of low emittance provide the basis for the intense, well-characterised neutrino beams necessary to elucidate the physics of flavour at the Neutrino Factory and to provide lepton-antilepton collisions up to several TeV at the Muon Collider. The international Muon Ionization Cooling Experiment (MICE) will demonstrate muon ionization cooling, the technique proposed to reduce the phase-space volume occupied by the muon beam at such facilities. In an ionization-cooling channel, the muon beam traverses a material (the absorber) loosing energy, which is replaced using RF cavities. The combined effect is to reduce the transverse emittance of the beam (transverse cooling). The configuration of MICE required to deliver the demonstration of ionization cooling is being prepared in parallel to the execution of a programme designed to measure the cooling properties of liquid-hydrogen and lithium hydride. The design of the cooling-demonstration experiment will be presented together with a summary of the performance of each of its components and the cooling performance of the experiment.
Submitted by the MICE speakers bureau that will identify later a member of the collaboration to present the contribution

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TUPMY006

MICE Step IV Optics without the M1 Coil in SSD

emittance, lattice, solenoid, scattering

1553

A. Liu
Fermilab, Batavia, Illinois, USA

Funding: Fermi National Accelerator Laboratory
The international Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling, the only technique that, given the short muon lifetime, can reduce the phase-space volume occupied by a muon beam quickly enough. MICE will demonstrate cooling in two steps. In the first one, Step IV, MICE will study the multiple Coulomb scattering in liquid hydrogen (LH2) and lithium hydride (LiH). A focus coil module will provide focussing on the absorber. The transverse emittance will be measured upstream and downstream of the absorber in two spectrometer solenoids (SS). Magnetic fields generated by two match coils in the SSs allow the beam to be matched into a flat-field regions in which the tracking detectors are installed. An incident in September 2015 rendered matching coil \#1 (M1D) of the downstream spectrometer inoperable. A new Step IV lattice without M1D and its optimization via a Genetic Algorithm (GA) will be described in this paper.

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TUPMY008

Phase Rotation of Muon Beams for Producing Intense Low-energy Muon Beams

experiment, proton, target, solenoid

1556

Y. Bao, Y. Bao, G. Hansen
UCR, Riverside, California, USA
D.V. Neuffer
Fermilab, Batavia, Illinois, USA

Low-energy muon beams are useful for rare decay researches, providing access to new physics that cannot be addressed at high-energy colliders. However, the large initial energy spread of the muon beam greatly limits the efficiency of muon applications. In this paper we outline a phase rotation method to significantly increase the intensity of low-energy muons. The muons are first produced by a short pulsed proton driver, and after a drift channel they form a time-momentum correlation. A series of rf cavities is used to bunch the muons and then phase rotate the bunches so that all the bunches reaches a momentum around 100 MeV/c. Then another group of rf cavities is used to decelerate the muon bunches to low-energy. Such a method produces low-energy muons with an efficiency of 0.1 muon per 8 GeV proton, which is significantly higher than the current Mu2e experiment at Fermilab, and it provides the possibility for the next generation rare decay researches.

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TUPMY009

MuSim, a Graphical User Interface for Multiple Simulation Programs

interface, proton, electron, real-time

1559

T.J. Roberts, M.A.C. Cummings, R.P. Johnson
Muons, Inc, Illinois, USA
D.V. Neuffer
Fermilab, Batavia, Illinois, USA

MuSim is a new user-friendly program designed to interface to many different particle simulation codes, regardless of their data formats or geometry descriptions. It presents the user with a compelling graphical user interface that includes a flexible 3-D view of the simulated world plus powerful editing and drag-and-drop capabilities. All aspects of the design can be parametrized so that parameter scans and optimizations are easy. It is simple to create plots and display events in the 3-D viewer (with a slider to vary the transparency of solids), allowing for an effortless comparison of different simulation codes. Simulation codes: G4beamline, MAD-X, and MCNP; more coming. Many accelerator design tools and beam optics codes were written long ago, with primitive user interfaces by today's standards. MuSim is specifically designed to make it easy to interface to such codes, providing a common user experience for all, and permitting the construction and exploration of models with very little overhead. For today's technology-driven students, graphical interfaces meet their expectations far better than text-based tools, and education in accelerator physics is one of our primary goals.

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TUPMY012

Hybrid Methods for Simulation of Muon Ionization Cooling Channels

experiment, emittance, scattering, lattice

1568

J.D. Kunz
IIT, Chicago, Illinois, USA
M. Berz, K. Makino
MSU, East Lansing, Michigan, USA
P. Snopok
Illinois Institute of Technology, Chicago, Illlinois, USA

Funding: Work is supported by the U.S. Department of Energy.
COSY Infinity is an arbitrary-order beam dynamics simulation and analysis code. It can determine high-order transfer maps of combinations of particle optical elements of arbitrary field configurations. New features are being developed for inclusion in COSY to follow the distribution of charged particles through matter. To study in detail some of the properties of muons passing through material, the transfer map approach alone is not sufficient. The interplay of beam optics and atomic processes must be studied by a hybrid transfer map–Monte Carlo approach in which transfer map methods describe the deterministic behavior of the particles in the accelerator channel, and Monte Carlo methods are used to model the stochastic processes intrinsic to liquid and solid absorbers. The advantage of the new approach is that the vast majority of the dynamics is represented by fast application of the high-order transfer map of an entire element and accumulated stochastic effects. The gains in speed are expected to simplify the optimization of muon cooling channels which are usually very computationally demanding. Progress on the development of the required algorithms is reported.

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TUPMY013

Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices

plasma, scattering, space-charge, emittance

1571

J.S. Ellison
IIT, Chicago, Illinois, USA
P. Snopok
Illinois Institute of Technology, Chicago, Illlinois, USA

Funding: Work supported by the U.S. Department of Energy.
New computational tools are essential for accurate modeling and simulation of the next generation of muon based accelerator experiments. One of the crucial physics processes specific to muon accelerators that has not yet been implemented in any current simulation code is beam induced plasma effect in liquid, solid, and gaseous absorbers. We report here on the progress of developing the required simulation tools and applying them to study the properties of plasma and its effects on the beam in muon ionization cooling channels.

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TUPMY032

Radiation from Open Ended Waveguide with a Dielectric Loading

radiation, vacuum, electron, controls

1617

S.N. Galyamin, A.A. Grigoreva, A.V. Tyukhtin, V.V. Vorobev
Saint-Petersburg State University, Saint-Petersburg, Russia
S. Baturin
LETI, Saint-Petersburg, Russia
S. Baturin
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Work is supported by the Grant of the President of Russian Federation (No. 6765.2015.2) and the Grants from Russian Foundation for Basic Research (No. 15-32-20985, 15-02-03913).
Terahertz radiation is considered as a promising tool for a number of applications. One possible way to emit THz waves is to pass short electron bunch through a waveguide structure loaded with dielectric*. In our previous papers, we have analyzed this problem in both approximate** and rigorous*** formulation. However, we have encountered certain difficulties with calculations. In the present report, we are starting to develop another rigorous approach based on mode-matching technique and modified residue-calculus technique. We consider the radiation from the open-ended dielectrically loaded cylindrical waveguide placed inside regular cylindrical waveguide with larger radius. We present structure of reflected and transmitted modes and typical radiation patterns from the open end of larger radius waveguide.
* S. Antipov et al., Appl. Phys. Lett., vol. 100, p. 132910, 2012.
** S.N. Galyamin et al., Opt. Express, vol. 22, No. 8, p. 8902, 2014.
*** S.N. Galyamin et al., in Proc. IPAC'15, pp. 2578-2580.

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TUPMY036

Drive Generation and Propagation Studies for the Two Beam Acceleration Experiment at the Argonne Wakefield Accelerator

kicker, laser, power-supply, wakefield

1629

N.R. Neveu, M.E. Conde, D.S. Doran, W. Gai, G. Ha, C.-J. Jing, W. Liu, J.G. Power, D. Wang, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea
N.R. Neveu
IIT, Chicago, Illinois, USA
D. Wang
TUB, Beijing, People's Republic of China

Funding: Work supported by by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
Simplified staging in a two beam accelerator (TBA) has been accomplished at the Argonne Wakefield Accelerator (AWA) facility. This layout consists of a drive beamline and witness beamline operating synchronously. The drive photoinjector linac produces a 70 MeV drive bunch train of eight electron bunches (charge per bunch between 5-40 nC) that pass through decelerating structures in each TBA stage. The witness linac produces an 8 MeV witness bunch that passes through the accelerating structures in each TBA stage. Recent effort has been focused on improving the uniformity of the UV laser pulses that generate the bunch trains. Current work at the AWA is focused on the transition from simplified staging to full staging. A kicker will be designed and installed to direct bunch trains to one TBA stage only. Preliminary calculations and simulation results are presented.

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TUPMY038

Preliminary Measurement of the Transfer Matrix of a TESLA-type Cavity at FAST

cavity, HOM, experiment, focusing

1632

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
N. Eddy, D.R. Edstrom, A. Lunin, P. Piot, J. Ruan, J.K. Santucci, J.K. Santucci, N. Solyak
Fermilab, Batavia, Illinois, USA

Funding: US Department of Energy (DOE) under contract DE-SC0011831 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359.
Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread application in Science and Industry. Many current and planned projects employ 1.3-GHz 9-cell superconducting cavities of the TESLA design*. In the present paper we discuss the transverse-focusing properties of such a cavity and non-ideal transverse-map effects introduced by field asymmetries in the vicinity of the input and high-order-mode radiofrequency (RF) couplers**. We especially consider the case of a cavity located downstream of an RF-gun in a setup similar to the photoinjector of the Fermilab Accelerator Science and Technology (FAST) facility. Preliminary experimental measurements of the CC2 cavity transverse matrix were carried out at the FAST facility. The results are discussed and compared with analytical and numerical simulations.
* A. Aunes et al., Phys. Rev.ST Accel. Beams 3, 092001 (2000).
** P. Piot, el. al., Proc. 2005 Part. Accel. Conf., Knoxville, TN, p. 4135 (2005).

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TUPOR001

Lifetime Improvements with a Harmonic RF System for the ESRF EBS

impedance, cavity, storage-ring, electron

1644

N. Carmignani, L. Farvacque, J. Jacob, S.M. Liuzzo, B. Nash, T.P. Perron, P. Raimondi, R. Versteegen, S.M. White
ESRF, Grenoble, France

A third-harmonic RF system to increase the Touschek lifetime is under study for the European Synchrotron Radiation Facility (ESRF) Extremely Brilliant Source (EBS) storage ring, in particular for modes with high current per bunch. Multi-particle simulations have been done to study the bunch lengthening and shape in presence of inductive impedance and a third-harmonic RF system.

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TUPOR005

A Parallelized Vlasov-Fokker-Planck-Solver for Desktop PCs

damping, synchrotron, bunching, collective-effects

1658

P. Schönfeldt, M. Brosi, A.-S. Müller, J.L. Steinmann
KIT, Karlsruhe, Germany

In order simulate the dynamics of an electron bunch due to the self-interaction with its own coherent synchrotron radiation it is a well established method to numerically solve the Vlasov-Fokker-Planck equation. In this paper we present a new, modularly extensible program that uses OpenCL to massively parallelize the computation, allowing a standard desktop PC to work with appropriate accuracy and yield reliable results within minutes. We provide numerical stability studies of over a huge parameter range and comparisons of our numerical results to other techniques.

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TUPOR008

Effect of the Various Impedances on Longitudinal Beam Stability in the CERN SPS

impedance, HOM, vacuum, operation

1666

A. Lasheen, T. Argyropoulos, J. Repond, E.N. Shaposhnikova
CERN, Geneva, Switzerland

The High Luminosity (HL)-LHC project at CERN aims at a luminosity increase by a factor ten and one of the necessary ingredients is doubling the bunch intensity to 2.4x10¹¹ ppb for beams with 25 ns bunch spacing. Many improvements are already foreseen in the frame of the LHC Injector Upgrade (LIU) project, but probably this intensity would still not be reachable in the SPS due to longitudinal instabilities. Recently a lot of effort went into finding the impedance sources of the instabilities. Particle simulations based on the latest SPS impedance model are now able to reproduce the measured instability thresholds and were used to determine the most critical impedance sources by removing them one by one from the model. It was found that impedance of vacuum flanges and of the already damped 630 MHz HOM of the main RF system gave for 72 bunches the comparable intensity thresholds. Possible intensity gains are defined for realistic impedance modifications and for various beam configurations (number of bunches, longitudinal emittances) and RF programs (single and double RF). The results of this study are used as a guideline for planning of a new campaign of the SPS impedance reduction.

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TUPOR009

Single Bunch Longitudinal Instability in the CERN SPS

impedance, flattop, synchrotron, emittance

1670

A. Lasheen, T. Bohl, S. Hancock, T. Roggen, E.N. Shaposhnikova
CERN, Geneva, Switzerland
E. Radvilas
Gediminas Technical University, Vilnius, Lithuania

The longitudinal single bunch instability observed in the SPS leads to uncontrolled emittance blow-up and limits the quality of high intensity beams required for the High Luminosity LHC and AWAKE projects at CERN. The present SPS impedance model developed from a thorough survey of machine elements was used in macro-particle simulations (with the code BLonD) of the bunch behavior through the acceleration cycle. Comparison of simulations with measurements of the synchrotron frequency shift, performed on the SPS flat bottom to probe the impedance, show a reasonable agreement. During extensive experimental studies various beam and machine parameters (bunch intensity, longitudinal emittance, RF voltage, with single and double RF systems) were scanned in order to further benchmark the SPS impedance model with measurements and to better understand the mechanism behind the instability. It was found that the dependence of instability threshold on longitudinal emittance and beam energy has an unexpected non-monotonic behavior, leading to islands of (in)stability. The results of this study are presented and can be used to define possible parameter settings for the future CERN projects.

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TUPOR010

Simulation of Instability at Transition Energy with a New Impedance Model for CERN PS

impedance, emittance, proton, synchrotron

1674

N. Wang
IHEP, Beijing, People's Republic of China
S. Aumon, N. Biancacci, M. Migliorati, G. Sterbini, N. Wang
CERN, Geneva, Switzerland
M. Migliorati
INFN-Roma1, Rome, Italy
S. Persichelli
University of Rome La Sapienza, Rome, Italy

Instabilities driven by the transverse impedance are proven to be one of the limitations for the high intensity reach of the CERN PS. Since several years, fast single bunch vertical instability at transition energy has been observed with the high intensity bunch serving the neu-tron Time-of-Flight facility (n-ToF). In order to better understand the instability mechanism, a dedicated meas-urement campaign took place. The results were compared with macro-particle simulations with PyHEADTAIL based on the new impedance model developed for the PS. Instability threshold and growth rate for different longitu-dinal emittances and beam intensities were studied.

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TUPOR011

Study of Microwave Instability for SLS-2

impedance, vacuum, storage-ring, emittance

1678

H.S. Xu, P. Craievich, M.M. Dehler, L. Stingelin
PSI, Villigen PSI, Switzerland

An ultra-low emittance electron storage ring is under development for the Upgrade of Swiss Light Source (SLS-2). An antechamber scheme consisting of round beam channel with 10 mm inner radius is considered to accommodate the required strong quadrupole and sextupole magnets, achieve the ultra-high vacuum, and absorb the undesired synchrotron radiation. However, the small size of vacuum chamber increases the susceptibility of the beam to the impedance induced collective instabilities. We will present the preliminary study of the microwave instability for SLS-2 storage ring considering the longitudinal Resistive-Wall (RW) impedance due to three different options for the beam chamber. The microwave instability thresholds are calculated under the conditions of two possible RF frequencies (100 MHz and 500 MHz) and three different materials (aluminum, copper, and stainless steel). The influences of third-harmonic cavities are also studied.

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TUPOR012

THz Coherent Synchrotron Radiation from Ultra-low Alpha Operating Mode at Diamond Light Source

storage-ring, radiation, impedance, electron

1682

T. Chanwattana, M. Atay, R. Bartolini
JAI, Oxford, United Kingdom
R. Bartolini, G. Cinque, M. Frogley, E. Koukovini-Platia, I.P.S. Martin
DLS, Oxfordshire, United Kingdom

Diamond Light Source is regularly operated in low-alpha mode to provide THz coherent synchrotron radiation (CSR) and short X-ray pulses for users. In order to maintain the wide frequency range of the coherent radiation whilst improving the signal to noise ratio, an ultra-low alpha mode has been considered to shorten the bunch length even further. In order to study this mode, the analysis of single bunch dynamics resulting from a variety of wakefield sources has been investigated using a single bunch multiparticle tracking code. These results are compared with measurements recorded using a Fourier transform infrared (FTIR) interferometer on the MIRIAM beam-line at Diamond.

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TUPOR013

Analysis of Multi-bunch Instabilities at the Diamond Storage Ring

impedance, damping, wakefield, storage-ring

1685

R. Bartolini, R.T. Fielder, G. Rehm
DLS, Oxfordshire, United Kingdom
V.V. Smaluk
BNL, Upton, Long Island, New York, USA

We present recent results of analytical, numerical and experimental analysis of multi-bunch instabilities at the Diamond storage ring. The works compares the impedance estimates from numerical modelling with the analysis of the growth rates of the excited multi-bunch modes in different machine configurations. The contribution of a number of wakefield sources has been identified with very high precision thanks to high quality data provided by the existing Transverse multi-bunch feedback diagnostics

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TUPOR017

Beam-beam Simulation of Crab Cavity with Frequence Dependent Noise for LHC Upgrade

luminosity, cavity, emittance, feedback

1691

J. Qiang
LBNL, Berkeley, California, USA
G. Arduini, Y. Papaphilippou, T. Pieloni
CERN, Geneva, Switzerland
J. Barranco
EPFL, Lausanne, Switzerland

High luminosity LHC upgrade will improve the luminosity of the current LHC operation by an order of magnitude. Crab cavity as a critical component for compensating luminosity loss from large crossing angle collision and also providing luminosity leveling for the LHC upgrade is being actively pursued. In this paper, we will report on the study of potential effects of the frequence-dependent crab cavity noise on the beam luminosity lifetime using strong-strong beam-beam simulations.

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TUPOR018

Design Optimization of Compensation Chicanes in the LCLS-II Transport Lines

FEL, electron, space-charge, undulator

1695

J. Qiang, C.E. Mitchell, M. Venturini
LBNL, Berkeley, California, USA
Y. Ding, P. Emma, Z. Huang, G. Marcus, Y. Nosochkov, T.O. Raubenheimer, L. Wang, M. Woodley
SLAC, Menlo Park, California, USA

LCLS-II is a 4th-generation high-repetition rate Free Electron Laser (FEL) based x-ray light source to be built at the SLAC National Accelerator Laboratory. To mitigate the microbunching instability, the transport lines from the exit of the Linac to the undulators will include a number of weak compensation chicanes with the purpose of cancelling the momentum compaction generated by the main bend magnets of the transport lines. In this paper, we will report on our design optimization study of these compensation chicanes in the presence of both longitudinal and transverse space-charge effects.

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TUPOR021

Incoherent Vertical Emittance Growth from Electron Cloud at CesrTA

dipole, electron, emittance, positron

1707

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

Funding: Work supported by the US National Science Foundation PHY-1416318, PHY-0734867, and PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538
We report on measurements of electron cloud (EC) induced tune shifts and emittance growth at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) with comparison to tracking simulation predictions. The simulations are based on a weak-strong model of the interaction of the positron beam (weak) with the electron cloud (strong), using electric fields computed with established EC buildup simulation codes (ECLOUD). Experiments were performed with 2.1 GeV positrons in a 30 bunch train with 14 ns bunch spacing and 9 mm bunch length, plus a witness bunch at varying distance from the train to probe the cloud as it decays. Measurements of the horizontal and vertical coherent tune shifts and horizontal and vertical bunch size were obtained for a range of train and witness bunch currents, and compared to simulations.

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TUPOR029

Study of Fast Instability in Fermilab Recycler

electron, dipole, betatron, proton

1728

S. A. Antipov
University of Chicago, Chicago, Illinois, USA
P. Adamson, S. Nagaitsev, M.-J. Yang
Fermilab, Batavia, Illinois, USA

One of the factors which may limit the intensity in the Fermilab Recycler is a fast transverse instability. It develops within a hundred turns and, in certain conditions, may lead to a beam loss. Various peculiar features of the instability: its occurrence only above a certain intensity threshold, and only in horizontal plane, as well as the rate of the instability, suggest that its cause is electron cloud. We studied the phenomena by observing the dynamics of stable and unstable beam. We found that beam motion can be stabilized by a clearing bunch, which confirms the electron cloud nature of the instability. The findings suggest electron cloud trapping in Recycler combined function mag-nets. Bunch-by-bunch measurements of betatron tune show a tune shift towards the end of the bunch train and allow the estimation of the density of electron cloud and the rate of its build-up. The experimental results are in agreement with numerical simulations of electron cloud build-up and its interaction with the beam.

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TUPOR030

Design of Octupole Channel for Integrable Optics Test Accelerator

octupole, optics, dynamic-aperture, electron

1731

S. A. Antipov
University of Chicago, Chicago, Illinois, USA
K. Carlson, A. Valishev, S.J. Wesseln
Fermilab, Batavia, Illinois, USA
R. Castellotti
SSSUP, Pisa, Italy

We present the design of octupole channel for Integrable Optics Test Accelerator (IOTA). IOTA is a test accelerator at Fermilab, aimed to conduct research towards high-intensity machines. One of the goals of the project is to demonstrate high nonlinear betatron tune shifts while retaining large dynamic aperture in a realistic accelerator design. At the first stage the tune shift will be attained with a special channel of octupoles, which creates a variable octupole potential over a 1.8 m length. The channel consists of 18 identical air-cooled octupole magnets. The magnets feature a simple low-cost design, while meeting the requirements on maximum gradient - up to 1.4 kG/cm³, and field quality - strength of harmonics below 1%. Numerical simulations show that the channel is capable of producing a nonlinear tune shift of 0.08 without restriction of dynamic aperture of the ring.

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TUPOW002

Current Status of the Milliampere Booster for the Mainz Energy-recovering Superconducting Accelerator

electron, experiment, linac, gun

1741

R.G. Heine, K. Aulenbacher, L.M. Hein, C. Matejcek
IKP, Mainz, Germany

Funding: Work supported by German Science Foundation (DFG) under the Cluster of Excellence "PRISMA" EXC1098/2014
The Milliampere Booster (MAMBO) is the injector linac for the Mainz Energy-recovering Superconducting Accelerator MESA. The MESA facility is currently under design at the Institut für Kernphysik (KPH) at Johannes Gutenberg University of Mainz (JGU). In this paper we will present the current design status of the linac.

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TUPOW006

Six-dimensional Phase-space Rotation and its Applications

emittance, FEL, cathode, electron

1754

M. Kuriki, K. Negishi
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, R. Kato, K. Ohmi, M. Satoh, Y. Seimiya, J. Urakawa
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Funding: This work is partly supported by Grant-in-Aid for Scientific Research by MEXT, Japan (KAKENHI) 25390126.
Recent progress on the accelerator science requires optimized phase space distributions of the beam for each applications. A classical approach to satisfy the requirements is minimizing the beam emittance with a bunch charge as much as possible. This classical approach is not efficient and not compatible to the beam dynamics nature. 6D phase-space rotation, e.g. z-x and x-y, gives a way to optimize the phase space distribution for various applications. In this article, we discus possible applications of the 6D phase space rotation. The x-y rotation generates the high aspect ratio beam for linear colliders directly without DR (Damping Ring). Combination of bunch clipping with a mechanical slit and x-z rotation can generate micro-bunch structure which is applicable for FEL enhancement and drive beam for dielectric acceleration. We present our theoretical and simulation study on these applications.

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TUPOW011

Profile Measurements of Bremsstrahlung Gamma-Rays from Tungsten Plates for Radioactive Isotope Production via Photonuclear Reaction using a 60 MeV Electron Linac

electron, quadrupole, detector, emittance

1766

K. Takahashi, H. Hama, F. Hinode, S. Kashiwagi, H. Kikunaga, T. Muto, I. Nagasawa, K. Nanbu, Y. Shibasaki, T. Suda, C. Tokoku, K. Tsukada
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Radioactive isotopes have been produced via photo-nuclear reaction using a 60 MeV high-power electron linac for research fields of nuclear chemistry and radioac-tive analysis at Research Center for Electron Photon Science (ELPH), Tohoku University. The electron beam with an average current more than 100 μA is transported to an electron-bremsstrahlung gamma-ray converter of 2 mm thickness platinum or tungsten plate at the irradiation station. A target of 10 mm diameter is placed 3 cm behind a converter. It is enclosed with a quartz glass in the water cooling system and is irradiated for photonuclear reaction. Since the correlation between the spatial profile of bremsstrahlung gamma-rays at the target position and accelerator parameters is of our primary interest, nickel thin films are irradiated and the profiles of bremsstrahlung gamma-rays are measured by intensity distribution measurements of 57Ni radioactivity using the phosphorus imaging plate. In the meantime, the beam emittance and Twiss parameters are measured.

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TUPOW014

Simulation of High Resolution Field Emission Imaging in an rf Photocathode Gun

electron, cathode, gun, solenoid

1769

J.H. Shao, H.B. Chen, J. Shi, X.W. Wu
TUB, Beijing, People's Republic of China
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
W. Gai
ANL, Argonne, Illinois, USA
F.Y. Wang
SLAC, Menlo Park, California, USA

Precisely locating field emission (FE) emitters on a realistic surface in rf structures is technically chal-lenging in general due to the wide emitting phase and the broad energy spread. A method to achieve in situ high resolution FE imaging has been proposed by using solenoids and a collimator to select electrons emitted at certain phases. The phase selection criterion and imaging properties have been studied by the beam dynamics code ASTRA. Detailed results are presented in this paper.

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TUPOW017

Twin Bunches at the FACET-II

wakefield, electron, acceleration, controls

1778

Z. Zhang
TUB, Beijing, People's Republic of China
M.J. Hogan, Z. Huang, A. Marinelli
SLAC, Menlo Park, California, USA

Twin electron bunches, generated, accelerated and compressed in the same acceleration bucket, have attracted a lot of interest in the free-electron lasers and wakefield acceleration. The recent successful experiment at the LCLS used twin bunches to generate two-color two x-ray pulses with tunable time delay and energy separation. In this note, we apply the twin bunches to the plasma wakefield acceleration. Numerical simulations show that based on the beamline of the FACET-II, we can generate high-intensity two electron bunches with time delay from ∼ 100 fs to picoseconds, which will benefit the control of high-gradient witness bunch acceleration in a plasma.

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TUPOW019

Preliminary Concept of Fast Positron Source Based on Photo-injector

positron, electron, target, linac

1785

Z. Chu, J.G. Guo, Q. Luo, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by National Natural Science Foundation of China (11375178 and 11575181) and the Fundamental Research Funds for the Central Universities, Grant No WK2310000046
Based on the past experience in slow positron beam, researchers at NSRL/USTC proposed a fast positron source for detection of material deep tiny flaws. Different from conventional positron sources used in positron annihilation techniques, the planned positron source will be a positron production linac, similar to positron injectors used in colliders. To compress the positron pulse, the bombarding electron beam comes from a short bunch photo-injector. A computer simulation was performed using EGS4 and PARMELA code. The bombarding electron bunch is 300pC, with an energy of 30MeV. Simulations results showed that it is reasonable to expect a beam of more than 10⁵ positrons per pulse for future positron annihilation studies. Further work is to be done to achieve precise control of beam energy.

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TUPOW021

Beam Dynamics Optimization and Future Plans for LUE-200 Linac Upgrade

beam-loading, klystron, bunching, linac

1788

S.M. Polozov, T.V. Bondarenko
MEPhI, Moscow, Russia
A.V. Butenko, V. Kobets, A.P. Sumbaev
JINR, Dubna, Moscow Region, Russia

The IREN facility (Intense Resonance Neutron Source) is now been tested and upgraded in JINR. The linear electron accelerator LUE-200 is used to generate intense fluxes of resonant photo-neutrons. Linac should deliver up to 200 MeV electron beam with 1 A or more current in 100 - 200 ns pulses. It consists of electron source, LEBT including buncher and two main accelerating sections (only one is installed up to now). Test operations shows that beam loading sufficiently influences the output beam parameters and beam energy after first section decreases from planned 55-60 MeV to 35 MeV. The buncher doesn't provide an efficient beam bunching also and beam recapturing by main section due to this is very low. Dynamics of the electron beam for traveling wave S-band linac LUE-200 was studied by numerical simulations. In report results of beam dynamics simulation and optimization taking into account beam loading discuss, parameters for new more effective buncher presents and first results of such buncher development shows.

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TUPOW023

New 10 MeV High-power Electron Linac for Industrial Application

linac, coupling, electron, bunching

1794

S.M. Polozov, D.S. Bazyl, T.V. Bondarenko, M. Gusarova, Yu.D. Kliuchevskaia, M.V. Lalayan, V.I. Rashchikov, E.A. Savin
MEPhI, Moscow, Russia
M.I. Demsky, A.A. Eliseev, V.V. Krotov, D.E. Trifonov
CORAD Ltd., St. Petersburg, Russia
B.S. Han, W.G. Kang, H.G. Park
EB TECH Co. Ltd., Daejeon, Republic of Korea

Joint team of CORAD and MEPhI developed a new industrial accelerating structure for average beam power up to 20 kW and energy range from 7.5 to 10 MeV. The use of modern methods and codes for beam dynamics simulation, raised coupling coefficient and group velocity of SW biperiodic accelerating structure allowed to reach high pulse power utilization and obtain high efficiency. Gentle buncher provides high capturing coefficient and narrow energy spectrum. The first linear accelerator with this structure was constructed and tested in collaboration with the company EB Tech.

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TUPOW028

Comparison of Model vs. Reality for VELA

gun, cathode, laser, solenoid

1810

M.S. Toplis, J.W. McKenzie, B.D. Muratori, D.J. Scott, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide a high quality electron beam for accelerator systems development, as well as industrial and scientific applications. Currently, the RF gun can deliver short bunches, of the order of 100 fs to a few ps, with a charge of up to 250 pC, at the longer bunch lengths, and up to 4.5 MeV/c beam momentum. A model for the injector has been developed in ASTRA, together with a suite of scripts to create scans of the available parameters around an empirically found arbitrarily optimal working point. The space of parameters consists of everything that can be changed in the control room, and ranges from bunch charge to laser spot size on the cathode, together with all magnet settings where and if necessary. The various scans facilitate the task of identifying where exactly the accelerator is in terms of parameters and trends. Initial comparisons of screen images are made between the model and reality. Ultimately, the goal of the model is to robustly and repeatably establish a desired operating setup on a daily basis from an unknown switch on condition.

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TUPOW032

Modelling of the Short Bunch Optics for BERLinPro

linac, emittance, space-charge, booster

1820

A. Ginter, A.N. Matveenko
HZB, Berlin, Germany

The Energy Recovery Linac principle allows compressing electron bunches to lengths at least two orders of magnitude shorter compared to storage rings. At BERLinPro bunch compression and decompression can be done in two stages in the injector and main arcs. Starting with different bunch lengths from the gun the distribution of compression between these two stages is subject to optimization. Simulations show that the length and shape of the bunch in the injector and before the linac are the limiting factors for minimal bunch length. Injector simulations have to consider space charge effects, whereas CSR effects are limiting compression in the arcs. The strength of these effects and optimal compression ratios changes with different bunch charges. Optimization and simulation tools have to be chosen according to the energy regime and dominant collective effects. Current status of injector optimization and effect on the compressed bunch are presented.

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TUPOW033

Status of the BERLinPro Main Linac Module

linac, cavity, HOM, wakefield

1823

H.-W. Glock, A. Frahm, J. Knobloch, A. Neumann
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
Beam operation of the BERLinPro energy recovery linac project, whose construction is under way, will initially start using the photoinjector and booster modules. In a second step the recirculation beam line and the main linac module will be added. Here the current design status of the main linac module is described. Results of wake field simulations are compared for different set ups. We also report on the manufacturing aspects including the design of the waveguide groups needed for HOM damping and the choice of flange-gasket-pairings appropriate for rectangular waveguides. Also mechanical considerations are included.

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TUPOW039

Simulation Study of the Beam Halo Formation for Beam Loss Estimation and Mitigation at KEK Compact ERL

cavity, operation, electron, gun

1843

O. Tanaka, T. Miyajima, N. Nakamura, T. Obina, M. Shimada, R. Takai
KEK, Ibaraki, Japan

Funding: Work supported by the "Grant-in-Aid for Creative Scientific Research" of JSPS (KAKENHI 15K04747)
At KEK Compact ERL (cERL) we are aiming to produce high-current and low-emittance electron beams (up to 10 mA) without significant beam loss. We believe that beam halo makes a significant impact into the beam loss. Therefore, we are performing beam loss simulations to meet the results of the beam loss measurements*. In particular, a simulation of the bunch tail originated from the electron gun was performed to understand the mechanisms of the beam halo formation. Since some measured beam profiles demonstrated unexpected halo particles, several factors such as misalignment of beam line elements and kicks from the steering coils were added into the simulation. Simulation study results are compared with the related beam loss and halo measurements here.
* Sakanaka et al., these proceedings

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TUPOW044

Experimental Investigation of THz Smith-Purcell Radiation From Composite Corrugated Capillary

radiation, detector, electron, vacuum

1861

K. Lekomtsev, A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
A. Ponomarenko, A.A. Tishchenko
MEPhI, Moscow, Russia

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
Terahertz part of electromagnetic spectrum has a variety of potential applications ranging from fundamental to security applications. Further advances in development of a linac based, tunable, and narrow band coherent source of THz radiation are very important. Mechanisms of Cherenkov radiation and Smith-Purcell radiation (SPR) [*] may be used for generation of THz radiation via coherent emission [**, ***]. In this report we will present experimental investigations of the SPR generated from the corrugated capillary with a reflector, using the femtosecond multi-bunch electron beam of LUCX accelerator at KEK, Japan [****]. LUCX is capable to generate a train of 4 bunches each with 200 femtosecond (60 micrometer) duration and 200 micrometer transverse size. We will discuss the composite design of the capillary, measurements of the SPR angular distributions and the comparison of these measurements with PIC simulations. In addition, we will discuss SPR spectral characteristics; bunch energy modulation, introduced by the corrugated capillary; and the way in which the bunch spacing changes the spectrum and angular distributions of SPR.
*K.Lekomtsev et al., NIMB 355 (2015) 164
**A. M. Cook et al., PRL 103, (2009) 095003.
***S. E. Korbly et al., PRL 94, (2005) 054803.
****A. Aryshev, arXiv:1507.03302 [physics.acc-ph]

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TUPOW045

Pre-bunched Electron Beam Emittance Simulation and Measurement

electron, emittance, gun, radiation

1864

Yu.D. Kliuchevskaia, S.M. Polozov
MEPhI, Moscow, Russia
A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

LUCX facility at KEK is used as the high brightness pre-bunched electron beam source for radiation experiments. Emittance measurement and optimization is one of the important research activities for newly developed operation mode of the facility. Characterization of the pre-bunched beam (THz sequence of a hundred femtosecond bunches) properties opens a possibility to establish detailed simulation of the THz FEL radiation yield and continuously improve pre-bunched beam dynamics insight. Emittance has been measured by the Q-scan method. The measurement results and possible ways of emittance optimization are discussed. The measurement results are compared with beam dynamics simulation done by self-consistent BEAMDULAC-BL code.

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TUPOW052

LLNL Laser-Compton X-ray Characterization

laser, electron, photon, background

1885

Y. Hwang, T. Tajima
UCI, Irvine, California, USA
G.G. Anderson, C.P.J. Barty, D.J. Gibson, R.A. Marsh
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
Laser-Compton X-rays have been produced at LLNL, and results agree very well with modeling predictions. An X-ray CCD camera and image plates were calibrated and used to characterize the 30 keV X-ray beam. A resolution test pattern was imaged to measure the source size. K-edge absorption images using thin foils confirm the narrow bandwidth of the source and offer electron beam diagnostics.

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TUPOY002

AOC, A Beam Dynamics Design Code for Medical and Industrial Accelerators at IBA

cyclotron, extraction, space-charge, synchro-cyclotron

1902

W.J.G.M. Kleeven, M. Abs, E. Forton, V. Nuttens, E.E. Pearson, J. Walle, S. Zaremba
IBA, Louvain-la-Neuve, Belgium

The Advanced Orbit Code (AOC) facilitates design studies of critical systems and processes in medical and industrial accelerators. Examples include: i) injection into and extraction from cyclotrons, ii) central region, beam-capture and longitudinal beam dynamics studies in synchro-cyclotrons, iii) studies of resonance crossings, iv) stripping extraction, v) beam simulation from the ion source to the extraction, vi) space charge effects, vii) beam transmission studies in gantries or viii) calculation of Twiss-functions. The main features of the code and some applications are discussed.

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TUPOY007

Development of a Compact X-Band Electron Linac for Production of Mo-99/Tc-99m

linac, electron, beam-loading, klystron

1917

J. Jang
The University of Tokyo, Tokyo, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
M. Yamamoto
Accuthera Inc., Kawasaki, Kanagawa, Japan

In response to the need of alternatives to the exhausted research reactors supplying Mo-99/Tc-99m, we are developing a compact X-band electron linear accelerator (linac). As an initial step, beam dynamics simulations were performed and electron beams of 35 MeV and 9.1 kW were obtained. We expect that sixteen linacs having these beam parameters can cover the demand of Tc-99m radiopharmaceuticals in Japan. On the other hand, we found that the combination of X-band RF and high beam power can give rise to instability of beam loading. We will therefore adjust and optimize the beam power while keeping Mo-99 production efficiency as high as possible.

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TUPOY016

The Optimized X-ray Target of Electron Linear Accelerator for Radiotherapy

target, electron, linac, detector

1933

N. Juntong, K. Pharaphan
SLRI, Nakhon Ratchasima, Thailand

The x-ray target in medical electron linear accelerator is an important part in the production of x-ray photon beam. X-ray dose rate is depended on materials and thickness of the target. For the low cost 6 MeV prototype of medical linac in Thailand, this study gives the optimized x-ray target in which the dose rate can be maximized. MCNP simulations were performed during an optimization for a high x-ray dose rate at 1 meter away from the target. Progression of the project is also presented.

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TUPOY019

Geant4 Simulations of Proton-induced Spallation for Applications in ADSR Systems

neutron, proton, target, experiment

1943

S.C. Lee
IIAA, Huddersfield, United Kingdom
C. Bungau, R. Cywinski
University of Huddersfield, Huddersfield, United Kingdom

Neutron spallation is an efficient process for producing intense neutron fluxes that can be exploited in Accelerator Driven Subcritical Reactors (ADSRs) for energy production and the transmutation of nuclear waste. In order to assess the feasibility of spallation driven fission and transmutation we have simulated proton induced neutron production using GEANT4, initially benchmarking our simulations against published experimental neutron spectra produced from a thick lead target bombarded with 0.5 and 1.5 GeV protons. The Bertini and INCL models available in GEANT4, coupled with the high precision (HP) neutron model, are found to adequately reproduce the published experimental data. Given the confidence in the GEANT4 simulations provided by this benchmarking we have then proceeded to simulate neutron production as a function of target geometry and thence to some preliminary studies of neutron production in an ADSR with a geometry similar to that of the proposed Belgian MYRRHA project. This paper presents the results of our GEANT4 benchmarking and simulations.

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TUPOY021

Characterisation of the Spectra of Spallation Neutron Sources through Modelling

neutron, proton, target, resonance

1950

R.J. Barlow, A. Rummana
IIAA, Huddersfield, United Kingdom
R. Seviour
University of Huddersfield, Huddersfield, United Kingdom

We characterise the neutron flux and energy spectra produced by protons on a lead target. This may enable studies of the neutronics of an ADSR, to be separated from the higher energy spallation processes, in order to explore te potential of ADSR as a better alternative for energy production, safety and waste transmutation. We consider a range of proton energies, and show how the numbers of neutrons produced can be fitted by some simple functions of the proton energy, as can the spatial and energy distributions. These calculations were performed in both MCNPX and Geant4 and we compare and benchmark the low energy neutron spectra obtained by MCNPX code and a Monte Carlo Code Geant4 against each other. Discrepancies were found for the low energy neutron spectrum, but by using different models as calculation options for low energy neutrons in Geant4, this disagreement has been significantly reduced.

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TUPOY023

A Compact and High Current FFAG for the Production of Radioisotopes for Medical Applications

target, proton, injection, space-charge

1957

D. Bruton, R.J. Barlow, T.R. Edgecock, R. Seviour
University of Huddersfield, Huddersfield, United Kingdom
C. Johnstone
PAC, Batavia, Illinois, USA

A low energy Fixed Field Alternating Gradient (FFAG) accelerator has been designed for the production of radioisotopes. Tracking studies have been conducted using the OPAL code, including the effects of space charge. Radioisotopes have a wide range of uses in medicine, and recent disruption to the supply chain has seen a renewed effort to find alternative isotopes and production methods. The design features separate sector magnets with non-scaling, non-linear field gradients but without the counter bends commonly found in FFAG's. The machine is isochronous at the level of 0.3% up to at least 28 MeV and hence able to operate in Continuous Wave (CW) mode. Both protons and helium ions can be used with this design and it has been demonstrated that proton beams with currents of up to 20 mA can be accelerated. An interesting option for the production of radioisotopes is the use of a thin internal target. We have shown that this design has large acceptance, ideal for allowing the beam to be recirculated through the target many times, the lost energy being restored on each cycle. In this way, the production of Technetium-99m, for example, can take place at the optimum energy.

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TUPOY024

Wave Particle Cherenkov Interactions Mediated via Novel Materials

acceleration, electron, operation, scattering

1960

A. Hopper
IIAA, Huddersfield, United Kingdom
R. Seviour
University of Huddersfield, Huddersfield, United Kingdom

Currently there is an increasing interest in dielectric wall accelerators. These work by slowing the speed of an EM wave to match the velocity of a particle beam, allowing wave-beam interactions, accelerating the beam. However conventional dielectric materials have limited interaction regions, so wave-beam energy transfer is minimal. In this paper we consider Artificial Materials (AMs), as slow wave structures, in the presence of charged particle beams to engineer Inverse-Cherenkov acceleration. AMs are periodic constructs whose properties depend on their subwavelength geometry rather than their material composition, and can be engineered to give an arbitrary dispersion relation. We show that Metamaterials, one example of an AM, can mediate an Inverse-Cherenkov interaction, but break down in high power environments due to high absorption. We consider AMs with low constitutive parameters and show they can exhibit low absorption whilst maintaining the ability to have a user defined dispersion relation, and mediate a wavebeam interaction leading to Inverse-Cherenkov acceleration.

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TUPOY027

Beam Dynamics Studies into Grating-based Dielectric Laser-driven Accelerators

electron, laser, accelerating-gradient, emittance

1970

Y. Wei, S.P. Jamison, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
K. Hanahoe, Y. M. Li, G.X. Xia
UMAN, Manchester, United Kingdom
S.P. Jamison
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.D.A. Smith
TXUK, Warrington, United Kingdom
Y. Wei, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: Work supported by the EU under grant agreement 289191 and the STFC under the Cockcroft Institute core grant ST/G008248/1.
Dielectric laser-driven accelerators (DLAs) based on gratings confine an electromagnetic field induced by a drive laser into a narrow vacuum channel where electrons travel and are accelerated. This can provide an alternative acceleration technology compared to conventional rf cavity accelerators. Due to the achievable high acceleration gradient of up to several GV/m this could pave the way for future ultra-short and low costμaccelerators. This contribution presents detailed beam dynamics simulations for multi-period double grating structures. Using the computer code VSim and realistic beam distributions, the achievable acceleration gradient and final beam quality in terms of emittance and energy spread are discussed. The results are then used for an overall optimization of the accelerating structure.

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TUPOY032

Design and Simulation of a Thermionic Electron Gun for a 1 MeV Parallel Feed Cockcroft-Walton Industrial Accelerator

electron, gun, cathode, space-charge

1976

M. Nazari, F. Abbasi
Shahid Beheshti University, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
M. Jafarzadeh
ILSF, Tehran, Iran

Electron accelerators are made of different parts and one of the main part of every electron accelerator is its electron gun. In this article a diode electron gun is designed and simulated for a 1MeV parallel feed Cockcroft-Walton accelerator for industrial applications. The pierce configuration is selected for focusing electrode. Simulations are carried out using CST Particle Studio. The gun is thermionic with indirect heating of spherical dispenser cathode that is made from porous tungsten which is impregnated with barium compounds. The gun maximum achievable current is 200 mA at 10 kV and required current in our accelerator is about 100 mA.

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TUPOY033

Design, Simulation and Comparison of Electrostatic Accelerating Tubes for a 1MeV Parallel Feed Cockcroft-Walton Industrial Accelerator

gun, electron, industrial-accelerators, vacuum

1979

M. Nazari, F. Abbasi
Shahid Beheshti University, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
M. Jafarzadeh
ILSF, Tehran, Iran

In this article accelerating tubes whit different geometries and different constructions are designed and simulated for a 1 MeV parallel feed Cockcroft-Walton electrostatic industrial accelerator. Simulations are carried out using CST Particle Studio. The accelerating tubes with different focusing electrode and accelerating electrode geometries are designed and simulated and compared with each other. Finally whit respect to the comparisons best geometry is selected. In this tube a 1 MV DC voltage is applied at several stages during the accelerating electrodes. Maximum electron beam current in the tube is 200 mA. In this application accelerating electrodes and focusing electrodes are made of stainless steel and insulators between electrodes are made of Borosilicate glass.

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TUPOY043

GEM*STAR Accelerator-Driven Subcritical System for Improved Safety, Waste Management, and Plutonium Disposition

neutron, proton, target, operation

1998

M.A.C. Cummings, R.P. Johnson, T.J. Roberts
Muons, Inc, Illinois, USA

Operation of high-power SRF particle accelerators at two US national laboratories allows us to consider a less-expensive nuclear reactor that operates without the need for a critical core, fuel enrichment, or reprocessing. A multipurpose reactor design that takes advantage of this new accelerator capability includes an internal spallation neutron target and high-temperature molten-salt fuel with continuous purging of volatile radioactive fission products. The reactor contains less than a critical mass and almost a million times fewer volatile radioactive fission products than conventional reactors like those at Fukushima. We describe GEMSTAR , a reactor that without redesign will burn spent nuclear fuel, natural uranium, thorium, or surplus weapons material. A first application is to burn 34 tonnes of excess weapons grade plutonium as an important step in nuclear disarmament under the 2000 Plutonium Management and Disposition Agreement **. The process heat generated by this W-Pu can be used for the Fischer-Tropsch conversion of natural gas and renewable carbon into 42 billion gallons of low-CO2-footprint, drop-in, synthetic diesel fuel for the DOD.

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WEOBA02

Commissioning of the China-ADS Injector-I Testing Facility

rfq, emittance, proton, cavity

2048

F. Yan, J.S. Cao, Y.L. Chi, R. Ge, H. Geng, S. Gu, D.Z. Guo, T.M. Huang, X. Jing, H. Li, R.L. Liu, F. Long, C. Meng, H.F. Ouyang, W.M. Pan, Q.L. Peng, Y.F. Sui, J.L. Wang, S.C. Wang, Z. Xue, Q. Ye, Y.L. Zhao
IHEP, Beijing, People's Republic of China

The 10 MeV accelerator-driven subcritical system (ADS) Injector I test stand at Institute of High Energy Physics (IHEP) is a testing facility dedicated to demonstrate one of the two injector design schemes [Injector Scheme-I, which works at 325 MHz], for the ADS project in China. The ion source was installed since April of 2014, periods of commissioning are regularly scheduled between installation phases of the rest of the injector. 6.05 MeV proton energy has been achieved with average beam current of 10 mA by 7 SC spoke cavities at present. This contribution reports the details of the commissioning results together with the challenges of the CW machine commissioning.

Slides WEOBA02 [5.243 MB]

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WEOCA03

Simulating Proton Synchrotron Radiation in the Arcs of the LHC, HL-LHC and FCC-hh

photon, optics, radiation, electron

2073

G. Guillermo Cantón, F. Zimmermann
CERN, Geneva, Switzerland
D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. We use the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we study the effect of the "sawtooth" chamber, for the HL-LHC the consequences of the ATS optics with large beta beating in the arcs, and for the FCC-hh the effect of a novel beam-screen design, with a long slit surrounded by a "folded" ante-chamber.

Slides WEOCA03 [0.329 MB]

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WEPMB003

Design of the HWR Cavities for SARAF

cavity, cryomodule, linac, pick-up

2119

G. Ferrand, L. Boudjaoui, D. Chirpaz-Cerbat, P. Hardy, F. Leseigneur, C. Madec, N. Misiara, N. Pichoff
CEA/IRFU, Gif-sur-Yvette, France

CEA is committed to delivering a Medium Energy Beam Transfer line and a superconducting linac (SCL) for SARAF accelerator in order to accelerate 5mA beam of either protons from 1.3 MeV to 35 MeV or deuterons from 2.6 MeV to 40 MeV. The SCL consists in 4 cryomodules. The first two identical cryomodules host 6 half-wave resonator (HWR) low beta cavities (β = 0.09) at 176 MHz. The last two identical cryomodule will host 7 HWR high-beta cavities (β = 0.18) at 176 MHz. Low-beta and high beta cavities have been optimized to limit electric and magnetic peak fields in the cavity, and to minimize the dissipated power. Manufacturing constraints and helium cooling were taken into consideration to minimize the risk during manufacturing and operation. Preliminary mechanical studies of the cavity and of the tuning system, as well as preliminary studies of the couplers and pick-up antennas were carried out. This work will be presented in this poster.

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WEPMB008

ESS DTL Mechanical Design and Prototyping.

DTL, vacuum, linac, dipole

2131

P. Mereu, M. Mezzano
INFN-Torino, Torino, Italy
D. Castronovo, R. Visintini
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
F. Grespan, A. Pisent, M. Poggi, C. R. Roncolato
INFN/LNL, Legnaro (PD), Italy

The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4% (3 ms pulse length, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. In this paper the DTL mechanical design and simulations are presented, together with the results obtained from the prototypes of three drift tubes, equipped respectively with Permanent Magnet Quadrupole, Steerer and Beam Position Monitor.

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WEPMB018

Multipactor Simulations in 650 MHz Superconducting Spoke Cavity for an Electron Accelerator

cavity, electron, multipactoring, laser

2161

T. Kubo, T. Saeki
KEK, Ibaraki, Japan
E. Cenni
CEA/IRFU, Gif-sur-Yvette, France
R. Hajima, M. Sawamura
JAEA, Ibaraki-ken, Japan
H. Hokonohara, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan

Funding: The work is supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
In order to realize a compact industrial-use X-ray source based on the laser-Compton scattering, a superconducting spoke cavity for an electron accelerator operated at 4K is under development. While the initially proposed operating frequency was 325MHz considering the 4K operation, we decided to start from the half scale model at 650MHz to accumulate our production experience of spoke cavity within our limited resources. In the present contribution, procedures and results of multipactor simulations for 650MHz spoke cavities are briefly introduced.

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WEPMB025

Fabrication of Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources

cavity, laser, photon, linac

2177

M. Sawamura, R. Hajima
QST, Tokai, Japan
H. Hokonohara, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
T. Kubo, T. Saeki
KEK, Ibaraki, Japan

Funding: The work is supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have launched a 5-year research program to develop superconducting spoke cavity for laser Compton scattered (LCS) photon sources. For realizing a wide use of LCS X-ray and γ-ray sources in academic and industrial applications, we adopt the super-conducting spoke cavity to electron beam drivers. The spoke cavity has advantages such as relative compactness in comparison with an elliptical cavity of the same frequency, robustness with respect to manufacturing inaccuracy due to its strong cell-to-cell coupling, the better packing in a linac to install couplers on outer conductor. On the other hand the spoke cavity has disadvantage of more complicated structure than an elliptical cavity. Though our proposal design for the photon source consists of the 325 MHz spoke cavities in 4K operation, we have begun to fabricate the half scale model of 650 MHz spoke cavity in order to accumulate our cavity production experience by effective utilization of our limited resources. In this paper, we present our fabrication status.

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WEPMB030

Design Study of a Compact Deflecting Cavity at IHEP

cavity, dipole, controls, linac

2188

J.P. Dai, B. Ni, J.Y. Zhai, J.R. Zhang
IHEP, Beijing, People's Republic of China

For the XFEL project proposed by IHEP, a sophisticated beam spreader is required to separate a single beam into multiple beams. One of the deflecting cavities used in the spreader has been investigated and optimized. It is a 325 MHz, compact RF-dipole superconducting cavity, with the transverse R/Q of 2900Ω, geometrical factor G of 88.5 Ω, and the Helium pressure sensitivity df/dp of 3.4 Hz/mbar. At the nominal deflecting voltage of 7MV, the peak electric field Epeak is 41 MV/m and peak magnetic field Bpeak is 48 mT. This paper will present the detailed RF and mechanical designs.

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WEPMB041

Design of RF Power Coupler for RISP Half Wave Resonator

impedance, cavity, vacuum, electron

2208

S. Lee, E.-S. Kim
Korea University Sejong Campus, Sejong, Republic of Korea
I. Shin
IBS, Daejeon, Republic of Korea

RF power couplers for half wave resonators are under development for the Rare Isotope Science Project (RISP) in Korea. It is required to deliver up to 6 kW RF power at 162.5 MHz to the HWR in CW mode. The RF coupler is a coaxial capacitive type using a disc type ceramic window. Design studies of 2nd prototype HWR RF coupler are presented.

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WEPMB045

Measurement of Higher Order Modes Electrodynamic Characteristics for Array of Two 2400 MHz Cavities

HOM, cavity, damping, higher-order-mode

2214

Ya.V. Shashkov, R.V. Donetskiy, M.V. Lalayan, N.P. Sobenin
MEPhI, Moscow, Russia
A. Orlov
NRNU, Moscow, Russia

Funding: *Work supported by Ministry of Education and Science grant 3.245.2014/r and the EU FP7 HiLumi LHC ' Grant Agreement 284404
In the frameworks of the High Luminosity Large hadron collider (HL-LHC) upgrade program an application of additional superconducting harmonic cavities operating at 800 MHz is currently under discussion. As a candidate, the two cavities with grooved beam pipes connected by the drift tube were suggested. In this article of measurements of Qload are performed for the aluminum model of array of two cavities connected by drift tube. Field distribution of Fundamental Mode (FM) and Higher Order Modes (HOM) were measured for aluminum prototype with a frequency of the operational mode of 2400 MHz, and their comparison with the simulation results.
Higher order modes

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WEPMB049

Transverse Defocusing Study in LPWA Channel for Linear and Bubble Modes

plasma, electron, laser, acceleration

2224

S.M. Polozov, V.I. Rashchikov, Ya.V. Shashkov
MEPhI, Moscow, Russia

Laser plasma wakefield acceleration (LPWA) is one of most popular novel trends of acceleration. The LPWA has two serous disadvantages as very high energy spread and low part of electrons capturing into acceleration. The waveguide and klystron type beam pre-modulation schemes was proposed *, ** to growth capturing and to limit the energy spectrum of 2-3 % for 200-300 MeV beam. One interesting effect was detected due to numerical simulation of beam dynamics in plasma channel. Not captured electrons are escape to the channel border fast and this effect should be explained. It was shown that such effect is caused by effective potential function which forms very high defocusing transverse field after its trailing edge. The results of such explanation verified by numerical simulations are discussed in report for linear and bubble LPWA modes.
* S.M. Polozov. NIM A, 729, p.517-521, 2013
** S.M. Polozov. Problems of Atomic Science and Technology. Series: Nuclear Physics Investigations, 6 (88), p. 29- 34, 2013

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WEPMB060

Modifications to the Pump Out Box to Lower the Qext of Diamond SCRF Cavities

cavity, coupling, operation, electron

2251

S.A. Pande, C. Christou, P. Gu
DLS, Oxfordshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

Diamond's CESR-B cavities are iris coupled and have fixed Qext. For reliability, the cavities are operated at lower voltages. This results in the optimum condition for beam loading being satisfied at a much lower power typically about 100 kW. For operation at 300 mA with two cavities, the RF power needed per system exceeds 200 kW. Consequently, the cavities need to be operated under-coupled. To lower the Qext and move the optimum operating point nearer to 200kW, 3 stub tuners are used in the waveguide feed line. The difference in the height of the coupling waveguide on cavity and that of the vacuum side waveguide on the window assembly results in a step transition which affects the Qext. The present window/step location results in Qext higher than that without the window. The Qext can be lowered by re-locating the RF window or by shifting the step change in the waveguide cross-section from its present location. This needs modification to the Pump Out box. The pros and cons of the proposed modification to the pump out box in terms of standing waves and multipacting characteristics studied with CST Studio are discussed in this paper.

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WEPMR002

Ultimate Gradient Limitation in Niobium Superconducting Accelerating Cavities

factory, SRF, niobium, cryogenics

2254

M. Checchin, A. Grassellino, M. Martinello, S. Posen, A. Romanenko
Fermilab, Batavia, Illinois, USA
M. Checchin, M. Martinello
Illinois Institute of Technology, Chicago, Illlinois, USA
J. Zasadzinski
IIT, Chicago, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The present study is addressed to the theoretical description of the ultimate gradient limitation in SRF cavities. Our intent is to exploit experimental data to confirm models which provide feed-backs on how to improve the current state-of-art. New theoretical insight on the cavities limiting factor can be suitable to improve the quench field of N-doped cavities, and therefore to take advantage of high Q0 at high gradients.

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WEPMR003

Tailoring Surface Impurity Content to Maximize Q-factors of Superconducting Resonators

cavity, superconductivity, niobium, factory

2258

M. Martinello, M. Checchin, A. Grassellino, O.S. Melnychuk, S. Posen, A. Romanenko, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA
M. Checchin, M. Martinello
Illinois Institute of Technology, Chicago, Illlinois, USA
J. Zasadzinski
IIT, Chicago, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Quality factor of superconducting radio-frequency (SRF) cavities is degraded whenever magnetic flux is trapped in the cavity walls during the cooldown. In this contribution we study how the trapped flux sensitivity, defined as the trapped flux surface resistance normalized for the amount of flux trapped, depends on the mean free path. A variety of 1.3 GHz cavities with different surface treatments (EP, 120 C bake and different N-doping) were studied in order to cover the largest range of mean free path nowadays achievable, from few to thousands of nanometers. A bell shaped trend appears for the range of mean free path studied. Over doped cavities falls at the maximum of this curve defining the largest values of sensitivity. In addition, we have also studied the trend of the BCS surface resistance contribution as a function of mean free path, revealing that N-doped cavities follow close to the theoretical minimum of the BCS surface resistance as a function of the mean free path. Adding these results together we unveil that optimal N-doping treatment allows to maximize Q-factor at 2 K and 16 MV/m until the magnetic field fully trapped during the cavity cooldown stays below 10 mG.

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WEPMR011

Simulations and Experimental Studies of Third Harmonic 3.9 Ghz CW Couplers for LCLS-II Project

cavity, operation, cryomodule, linac

2280

N. Solyak, I.V. Gonin, E.R. Harms, S. Kazakov, T.N. Khabiboulline, A. Lunin
Fermilab, Batavia, Illinois, USA

LCLS-II linac is based on SRF technology developed for the XFEL project. The XFEL 3rd harmonic system built by INFN is based on the original designs of cavity and power coupler developed and built by Fermilab for the FLASH facility at DESY. For LCLS-II application both designs of the 3.9 GHz cavity and the power coupler have been modified for an operation in the continuous wave regime up to 2 kW average RF power. In this paper we discuss coupler modifications and the result multiphysics analysis for various operating regimes. For the initial test of a proposed design, we decided to modify two spare warm sections of power couplers, built for the FLASH facility, by shortening both of two inner bellows and making a thicker copper plating. Modification of the existing coupler test stand and the test program are briefly discussed in this paper.

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WEPMR013

Study of LCLS-II Fundamental Power Coupler Heating in HTS Integrated Cavity Tests

cavity, resonance, HOM, vacuum

2286

N. Solyak, I.V. Gonin, A. Grassellino, C.J. Grimm, T.N. Khabiboulline, J.P. Ozelis, K. Premo, O.V. Prokofiev, D.A. Sergatskov, G. Wu
Fermilab, Batavia, Illinois, USA

LCLS-II coupler based on modified design of TTF3 coupler for higher average power was assembled on high Q cavity and tested at HTS as part of integrated cavity test program. Couplers were thermally connected to thermal shields and equipped with diagnostics to control temperature in different locations and provide information about cryogenic heat loads at 2 K, 5 K and 80 K.Three dressed cavities with power couplers were tested in HTS at full specified RF power. Results are summarized in this paper and cross-checked with simulation.

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WEPMR018

Time Resolved Cryogenic Cooling Analysis of the Cornell Injector Cryomodule

HOM, cryogenics, cryomodule, operation

2298

R.G. Eichhorn, A.C. Bartnik, B.M. Dunham, G.M. Ge, G.H. Hoffstaetter, H. Lee, M. Liepe, S.R. Markham, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

To demonstrate key parameters of a an energy recovery linac (ERL) at Cornel, an injector based on a photo gun and an SRF cryomodule was designed and built. The goal was to demonstrate high current generation while achieving low emittances. While the emittance goal has been reached, the current achieved so far is 75 mA. Even though this is a world record, it is still below the targeted 100 mA. While ramping up the current we observed excessive heating in the fundamental power coupler which we were able to track down to insufficient cooling of the 80 K intercepts. These intercepts are cooled by a stream of parallel cryogenic flows which we found to be unbalanced. In this paper we will review the finding, describe the analysis we did, modeling of the parallel flow and the modifications made to the module to overcome the heating.

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WEPMR021

HOM Measurements for Cornell's High-current CW ERL Cryomodule

HOM, cavity, cryomodule, linac

2309

F. Furuta, R.G. Eichhorn, G.M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, P. Quigley, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The main linac cryomodule (MLC) for the future energy-recovery linac (ERL) based synchrotron-light facility at Cornell had been designed, fabricated, and tested. It houses 6 SRF cavities with individual higher order-modes (HOMs)absorbers and one magnet/ BPM section. We will report the HOM study on MLC.

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WEPMR025

Improved N-Doping Protocols for SRF Cavities

cavity, niobium, SRF, radio-frequency

2323

D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, T. Gruber, G.H. Hoffstaetter, J.J. Kaufman, P.N. Koufalis, M. Liepe, J.T. Maniscalco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: NSF, DOE
Nitrogen-doping has been shown to consistently produce better quality factors in SRF cavities than is achievable with standard preparation techniques. Unfortunately, nitrogen-doping typically brings with it lower quench fields and higher sensitivities of residual resistance to trapped magnetic flux. Here we present work to understand these effects in hopes of mitigating them while maintaining the high Q desired by future projects. Using a nitrogen diffusion simulation, material parameters of nitrogen-doped cavities can be predicted prior to doping. These simulations results are consistent with SIMS data taken from samples treated with cavities. The nature of doping's effect on quench field has also been studied using CW and pulsed measurements. These results have allowed us to better understand the nature of nitrogen-doping and its effect on cavity performance.

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WEPMR038

Frequency Tuning for a DQW Crab Cavity

cavity, operation, SRF, insertion

2357

S. Verdú-Andrés, I. Ben-Zvi, J. Skaritka, Q. Wu, B. P. Xiao
BNL, Upton, Long Island, New York, USA
K. Artoos, R. Calaga, O. Capatina, R. Leuxe, C. Zanoni
CERN, Geneva, Switzerland
I. Ben-Zvi
Stony Brook University, Stony Brook, USA

Funding: Work supported by US DOE via BSA LLC contract No.DE-AC02-98CH10886, the US LARP program, US DOE contract No. DE-AC02-05CH1123 (NERSC resources) and by HiLumi project.
The nominal operating frequency for the HL-LHC crab cavities is 400.79 MHz within a bandwidth of ±60kHz. Attaining the required cavity tune implies a good understanding of all the processes that influence the cavity frequency from the moment when the cavity parts are being fabricated until the cavity is installed and under operation. Different tuning options will be available for the DQW crab cavity of LHC. This paper details the different steps in the cavity fabrication and preparation that may introduce a shift in the cavity frequency and introduces the different tuning methods foreseen to bring the cavity frequency to meet the specifications.

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WEPMW001

End-to-End Beam Simulations for the New Muon G-2 Experiment at Fermilab

proton, target, storage-ring, experiment

2408

M. Korostelev, I.R. Bailey, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
I.R. Bailey
Lancaster University, Lancaster, United Kingdom
A. Herrod, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
J.P. Morgan
Fermilab, Batavia, Illinois, USA
W. Morse, D. Stratakis, V. Tishchenko
BNL, Upton, Long Island, New York, USA

The aim of the new muon g-2 experiment at Fermilab is to measure the anomalous magnetic moment of the muon with an unprecedented uncertainty of 140 ppb. A beam of positive muons required for the experiment is created by pion decay. Detailed studies of the beam dynamics and spin polarization of the muons are important to predict systematic uncertainties in the experiment. In this paper, we present the results of beam simulations and spin tracking from the pion production target to the muon storage ring. The end-to-end beam simulations are developed in Bmad and include the processes of particle decay, collimation (with accurate representation of all apertures) and spin tracking.

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WEPMW002

A CLIC Damping Wiggler Prototype at ANKA: Commissioning and Preparations for a Beam Dynamics Experimental Program

wiggler, damping, storage-ring, operation

2412

A. Bernhard, S. Casalbuoni, S. Gerstl, J. Gethmann, A.W. Grau, E. Huttel, A.-S. Müller, D. Saez de Jauregui, N.J. Smale
KIT, Karlsruhe, Germany
A.V. Bragin, S.V. Khrushchev, N.A. Mezentsev, V.A. Shkaruba, V.M. Tsukanov, K. Zolotarev
BINP SB RAS, Novosibirsk, Russia
P. Ferracin, L. Garcia Fajardo, Y. Papaphilippou, H. Schmickler, D. Schoerling, P. Zisopoulos
CERN, Geneva, Switzerland

Funding: This work is partially funded by the German Federal Ministry of Education and Research under grant 05K12VK1
In a collaboration between CERN, BINP and KIT a prototype of a superconducting damping wiggler for the CLIC damping rings has been installed at the ANKA synchrotron light source. On the one hand, the foreseen experimental program aims at validating the technical design of the wiggler, particularly the conduction cooling concept applied in its cryostat design, in a long-term study. On the other hand, the wiggler's influence on the beam dynamics particularly in the presence of collective effects is planned to be investigated. ANKA's low-alpha short-bunch operation mode will serve as a model system for these studies on collective effects. To simulate these effects and to make verifiable predictions an accurate model of the ANKA storage ring in low-alpha mode, including the insertion devices is under parallel development. This contribution reports on the first operational experience with the CLIC damping wiggler prototype in the ANKA storage ring and steps towards the planned advanced experimental program with this device.

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WEPMW013

Bunch Splitting Simulations for the JLEIC Ion Collider Ring

emittance, ion, collider, synchrotron

2448

B.R.P. Gamage, T. Satogata
ODU, Norfolk, Virginia, USA
T. Satogata
JLab, Newport News, Virginia, USA

We describe the bunch splitting strategies for the proposed JLEIC ion collider ring at Jefferson Lab. This complex requires an unprecedented 9:6832 bunch splitting, performed in several stages. We outline the problem and current results, optimized with ESME including general parameterization of 1:2 bunch splitting for JLEIC parameters.

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WEPMW014

Development of the Electron Cooling Simulation Program for JLEIC

electron, ion, emittance, collider

2451

H. Zhang, J. Chen, R. Li, Y. Zhang
JLab, Newport News, Virginia, USA
H. Huang, L. Luo
ODU, Norfolk, Virginia, USA

Funding: Work supported by the Department of Energy, Laboratory Directed Research and Development Funding, under Contract No. DE-AC05-06OR23177
In the JLab Electron Ion Collider (JLEIC) project the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during collision at the collider ring. A new electron cooling process simulation program has been developed to fulfill the requirements of the JLEIC electron cooler design. The new program allows the users to calculate the electron cooling rate and simulate the cooling process with either DC or bunched electron beam to cool either coasting or bunched ion beam. It has been benchmarked with BETACOOL in aspect of accuracy and efficiency. In typical electron cooling process of JLEIC, the two programs agree very well and we have seen a significant improvement of computational speed using the new one. Being adaptive to the modern multicore hardware makes it possible to further enhance the efficiency for computationally intensive problems. The new program is being actively used in the electron cooling study and cooler design for JLEIC. We will present our models and some simulation results in this paper.

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WEPMW028

First Attempts at using Active Halo Control at the LHC

emittance, controls, collimation, electron

2486

J.F. Wagner
Goethe Universität Frankfurt, Frankfurt am Main, Germany
R. Bruce, H. Garcia Morales, W. Höfle, G. Kotzian, R. Kwee-Hinzmann, A. Langner, A. Mereghetti, E. Quaranta, S. Redaelli, A. Rossi, B. Salvachua, R. Tomás, G. Valentino, D. Valuch, J.F. Wagner
CERN, Geneva, Switzerland
G. Stancari
Fermilab, Batavia, Illinois, USA

Funding: Research supported by the High Luminosity LHC project.
The beam halo population is a non-negligible factor for the performance of the LHC collimation system and the machine protection. In particular this could become crucial for aiming at stored beam energies of 700 MJ in the High Luminosity (HL-LHC) project, in order to avoid beam dumps caused by orbit jitter and to ensure safety during a crab cavity failure. Therefore several techniques to safely deplete the halo, i.e. active halo control, are under development. In a first attempt a novel way for safe halo depletion was tested with particle narrow-band excitation employing the LHC Transverse Damper (ADT). At an energy of 450 GeV a bunch selective beam tail scraping without affecting the core distribution was attempted. This paper presents the first measurement results, as well as a simple simulation to model the underlying dynamics.

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WEPMW029

Simulation of Heavy-Ion Beam Losses with the SixTrack-FLUKA Active Coupling

ion, heavy-ion, coupling, collimation

2490

P.D. Hermes, R. Bruce, F. Cerutti, A. Ferrari, J.M. Jowett, A. Lechner, A. Mereghetti, D. Mirarchi, P.G. Ortega, S. Redaelli, B. Salvachua, E. Skordis, G. Valentino, V. Vlachoudis
CERN, Geneva, Switzerland

Funding: Work suppported by the Wolfgang Gentner Programme of the German BMBF
The LHC heavy-ion program aims to further increase the stored ion beam energy, putting high demands on the LHC collimation system. Accurate simulations of the ion collimation efficiency are crucial to validate the feasibility of new proposed configurations and beam parameters. In this paper we present a generalized framework of the SixTrack-FLUKA coupling to simulate the fragmentation of heavy-ions in the collimators and their motion in the LHC lattice. We compare heavy-ion loss maps simulated on the basis of this framework with the loss distributions measured during heavy-ion operation in 2011 and 2015.

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WEPMW030

Cleaning Performance of the Collimation System of the High Luminosity Large Hadron Collider

collimation, ion, insertion, luminosity

2494

D. Mirarchi, A. Bertarelli, R. Bruce, F. Cerutti, P.D. Hermes, A. Lechner, A. Mereghetti, E. Quaranta, S. Redaelli
CERN, Geneva, Switzerland
R.B. Appleby
UMAN, Manchester, United Kingdom
H. Garcia Morales, R. Kwee-Hinzmann
Royal Holloway, University of London, Surrey, United Kingdom

Different upgrades of the LHC will be carried out in the framework of the High Luminosity project (HL-LHC), where the total stored energy in the machine will increase up to about 700 MJ. This unprecedented stored energy poses serious challenges for the collimation system, which was designed to handle safely up to about 360 MJ. In this paper the baseline collimation layout for HL-LHC is described, with main focus on upgrades related to the cleaning of halo and physics debris, and its expected performance is discussed. The main upgrade items include the presence of new collimators in the dispersion suppressor of the betatron cleaning insertion installed between two 11 T dipoles, and two additional collimators for an improved local protection of triplet magnets. Thus, optimized settings for the entire and upgraded collimation chain were conceived and are shown here together with the resulting cleaning performance. Moreover, the cleaning performance taking into account crab cavities it is also discussed.

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WEPMW031

Towards Optimum Material Choices for the HL-LHC Collimator Upgrade

impedance, collimation, beam-losses, luminosity

2498

E. Quaranta, A. Bertarelli, N. Biancacci, R. Bruce, F. Carra, E. Métral, S. Redaelli, A. Rossi, B. Salvant
CERN, Geneva, Switzerland
F. Carra
Politecnico di Torino, Torino, Italy

The first years of operation at the LHC showed that collimator material-related concerns might limit the performance. In addition, the HL-LHC upgrade will bring the accelerator beyond the nominal performance through more intense and brighter proton beams. A new generation of collimators based on advanced materials is needed to match present and new requirements. After several years of R&D on collimator materials, studying the behaviour of novel composites with properties that address different limitations of the present collimation system, solutions have been found to fulfil various upgrade challenges. This paper describes the proposed staged approach to deploy new materials in the upgraded HL-LHC collimation system. Beam tests at the CERN HiRadMat facility were also performed to benchmark simulation methods and constitutive material models.

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WEPMW033

Validation of Simulation Tools for Fast Beam Failure Studies in the LHC

optics, collimation, proton, beam-losses

2506

E. Quaranta, C. Bracco, R. Bruce, S. Redaelli
CERN, Geneva, Switzerland

The LHC collimation system protects passively the most sensitive machine equipment against beam losses. In particular, collimators are the last line of defense in case of single-turn failures that cannot be caught by the standard interlock system. The collimator settings are conceived to protect the machine even for very rare events, like beam abort failures with a full machine. Collimator settings are established in simulations through a dedicated tracking setup but also empirically validated by beam measurements at low intensities. A benchmark of simulations is essential for reliably estimating the response of the system for future machine configurations and beam parameters. In the paper, results are presented of tracking simulations for different optics deployed in the LHC Run II at 6.5 TeV and compared with data.

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WEPMW036

MERLIN Cleaning Studies with Advanced Collimator Materials for HL-LHC

scattering, collimation, proton, hadron

2514

A. Valloni, R. Bruce, A. Mereghetti, E. Quaranta, S. Redaelli
CERN, Geneva, Switzerland
R.B. Appleby
UMAN, Manchester, United Kingdom
J. Molson
LAL, Orsay, France
H. Rafique
University of Huddersfield, Huddersfield, United Kingdom

The challenges of the High-Luminosity upgrade of the Large Hadron Collider require improving the beam collimation system. An intense R&D program has started at CERN to explore novel materials for new collimator jaws to improve robustness and reduce impedance. Particle tracking simulations of collimation efficiency are performed using the code MERLIN which has been extended to include new materials based on composites. After presenting two different implementations of composite materials tested in MERLIN, we present simulation studies with the aim of studying the effect of the advanced collimators on the LHC beam cleaning.

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WEPMW037

MERLIN Simulations of the LHC Collimation System with 6.5 TeV Beams

collimation, proton, scattering, betatron

2518

A. Valloni
Rome University La Sapienza, Roma, Italy
R.B. Appleby, S.C. Tygier
UMAN, Manchester, United Kingdom
R. Bruce, A. Mereghetti, S. Redaelli
CERN, Geneva, Switzerland
J. Molson
LAL, Orsay, France
H. Rafique
University of Huddersfield, Huddersfield, United Kingdom

The accelerator physics code MERLIN has been extended in many areas to make detailed studies of the LHC collima- tion system and calculate loss maps from beam halo losses. Large scale tracking simulations have been produced for the 2015 run configuration at 6.5 TeV. We present results of cleaning inefficiency simulations of the LHC's multi-stage collimation system along with a detailed comparison be- tween MERLIN, SixTrack, and measured beam losses.

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WEPMW044

Start-to-End Simulation of eRHIC ERL

linac, electron, emittance, synchrotron-radiation

2535

Y. Hao, S.J. Brooks, Y.C. Jing, F. Méot, V. Ptitsyn, D. Trbojevic, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The ERL-ring eRHIC adopts the electron accelerator design of a multi-pass energy recovery linac (ERL), with fixed field alternating gradient (FFAG) recirculating passes. To ensure the beam quality in the accelerating and decelerating stage and the energy recovery efficiency, detailed start-to-end simulation is required to evaluate the various beam dynamics effects, such as synchrotron radiation, wake fields, coherent synchrotron radiation. In this paper, we present the eRHIC ERL start-to-end simulation strategy with various simulation codes and the current status.

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WEPMY006

A High Transformer Ratio Scheme for PITZ PWFA Experiments

plasma, wakefield, laser, acceleration

2551

G. Loisch, M. Groß, H. Huck, A. Oppelt, Y. Renier, F. Stephan
DESY Zeuthen, Zeuthen, Germany
A. Aschikhin, A. Martinez de la Ossa, J. Osterhoff
DESY, Hamburg, Germany
M. Hochberg, M. Sack
KIT, Karlsruhe, Germany

In the field of plasma wakefield acceleration (PWFA) significant progress has been made throughout the recent years. However, an important issue in building plasma based accelerators that provide particle bunches suitable for user applications will be a high transformer ratio, i.e. the ratio between maximum accelerating field in the witness and maximum decelerating fields in the driver bunch. The transformer ratio for symmetrical bunches in an overdense plasma is naturally limited to 2*. Theory and simulations show that this can be exceeded using asymmetrical bunches. Experimentally this was proven in RF-structures**, but not in PWFA. To study transformer ratios above this limit in the linear regime of a plasma wake, an experimental scheme tailored to the unique capabilities of the Photoinjector Test Facility Zeuthen PITZ, a 20-MeV electron accelerator at DESY, is being investigated. This includes analytical plasma wakefield calculations, numerical simulations of beam transport and plasma wakefields, as well as preparatory studies on the photocathode laser system and the plasma sources.
* K. L. F. Bane, P. B. Wilson and T. Weiland, AIP Conference Proceedings 127, p. 875, 1984
** C. Jing et al., Physical Review Letters 98, 144801, 2007

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WEPMY009

Transverse Tolerances of a Multi-Stage Plasma Wakefield Accelerator

emittance, plasma, linear-collider, acceleration

2561

C.A. Lindstrøm, E. Adli, J. Pfingstner
University of Oslo, Oslo, Norway
E. Marín, D. Schulte
CERN, Geneva, Switzerland

Funding: This work is supported by the Research Council of Norway.
Plasma wakefield acceleration (PWFA) provides GeV/m-scale accelerating fields, ideal for applications such as a future linear collider. However, strong focusing fields imply that a transversely offset beam with an energy spread will experience emittance growth from the energy dependent betatron oscillation. We develop an analytic model for estimating tolerances from this effect, as well as an effective simplified simulation tool in Elegant. Estimations for a proposed 1 TeV PWFA linear collider scheme indicate tight tolerances of order 40 nm and 1 μrad in position and angle respectively.

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WEPMY014

Feasibility Study of a Laser-Driven High Energy Electron Acceleration in a Long Up-Ramp Density

electron, plasma, laser, acceleration

2576

M. Kim, J. Kim, S.W. Lee, I.H. Nam, H. Suk
GIST, Gwangju, Republic of Korea

Laser-driven wakefield acceleration (LWFA) has received much attention as it can produce GeV-level high-energy electrons in cm-scale distance*. However, the accelerated electron energies are still limited by several factors, especially by the dephasing problem that is caused by different velocities between the plasma wake wave and the accelerated electron beam. In order to increase the acceleration length restricted by the dephasing problem**, we developed a gas-cell with density-tapering, which is realized by applying different gas pressures into two gas inlets in the gas cell. In this way, the gas density and gradient can be easily controlled in the gas cell. We used the density-tapered gas-cell for laser wakefield acceleration experiments in our laboratory with a 20 TW/40 fs Ti:sapphire laser system***. The results show that the electron energy can be significantly enhanced (about twice) with the tapered density gas-cell, compared with a uniform density conventional gas-cell. In this presentation, we show the experimental results and comparison with two-dimensional (2-D) particle-in-cell (PIC) simulation results.
* W. P. Leemans et al. Phy. Rev. Lett. 113, 245002 (2014).
** M. S. Kim et al. Appl. Phy. Lett. 102, 204103 (2013).
*** I. H. Nam et al. Curr. Appl. Phy. 15, 468 (2015).

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WEPMY016

Development of RF System for Measuring Plasma Density Modulation of Proton Beam-driven Plasma Wakefield

plasma, wakefield, proton, focusing

2582

S.Y. Kim, M. Chung
UNIST, Ulsan, Republic of Korea

Proton beam-driven plasma wakefield acceleration technique using the proton beam of Super Proton Syn-chrotron (SPS) at CERN has been actively researched these days. Plasma density modulation due to the proton beam will generate high-gradient's electric field within the modulated plasma. The key role is Self-Modulation Instability (SMI) of the long proton beam. To understand SMI phenomena, we have studied RF system such as heterodyne system for measuring modulated plasma den-sity caused by the SMI. In this work, we design the details of the RF system and optical system of focusing millimetre-sized electromagnetic wave using CODE V and plasma-electromagnetic wave interactions using simulation tools.

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WEPMY017

Numerical Studies of Self Modulation Instability in the Beam-driven Plasma Wakefield Experiments

plasma, proton, electron, wakefield

2585

K. Moon, M. Chung
UNIST, Ulsan, Republic of Korea

Proton beam-driven plasma wakefield acceleration was recently proposed as a way to bring electrons to TeV energy range in a single plasma section. When the ultra-relativistic long proton beam propagates into the plasmas, this bunch splits into many small bunches. This phenomenon is known as a Self-Modulation Instability (SMI), and its characteristics depend on the ratio of bunch length and plasma wavelength. In this study, we first introduce a Particle-In-Cell (PIC) code WARP, focusing on the basis of parallel version structure. Through numerical simulations using the WARP, we investigate the characteristics of the SMI and propose possible experimental setup at the Injector Test Facility (ITF) of Pohang Accelerator Laboratory (PAL). Also, we present dependencies of the witness beam quality on both the driver beam and plasma parameters.

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WEPMY022

Homogeneous Focusing of Train of Short Relativistic Electron Bunches by Plasma Wakefield

focusing, plasma, wakefield, electron

2599

V.I. Maslov, I.N. Onishchenko
NSC/KIPT, Kharkov, Ukraine
I.P. Levchuk (Yarovaya)
KhNU, Kharkov, Ukraine

The focusing of bunches by wakefield, excited in plasma by resonant sequence of relativistic electron bunches (repetition frequency of the bunches coincides with the plasma frequency), is inhomogeneous. In this paper we investigate wakefield plasma lens, in which all bunches of sequence are focused identically and uniformly, for short relativistic electron bunches. For this it is necessary that the charge of 1-st bunch is smaller in determined times than the charges of the other bunches, the interval between back front of 1-st bunch and 1-st front of 2-nd bunch equals determined value, the interval between back front of N-th bunch and 1-st front of (N+1)-th bunch for all other bunches is multiple to excited wavelength. It is shown that only 1-st bunch is in finite Ez≠0. Other bunches are in zero longitudinal electrical wakefield. Hence the 1-st bunch interchange by energy with wakefield. The subsequent bunches don't interchange by energy with wakefield and the amplitude of wakefield doesn't change along sequence. Radial wake force Fr in regions, occupied by bunches, is approximately constant along bunches.

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WEPMY024

A Spectrometer for Proton Driven Plasma Accelerated Electrons at AWAKE - Recent Developments

plasma, electron, proton, emittance

2605

L.C. Deacon, S. Jolly, F. Keeble, M. Wing
UCL, London, United Kingdom
B. Biskup, A. Goldblatt, S. Mazzoni, A.V. Petrenko
CERN, Geneva, Switzerland
B. Biskup
Czech Technical University, Prague 6, Czech Republic
M. Wing
DESY, Hamburg, Germany
M. Wing
University of Hamburg, Hamburg, Germany

The AWAKE experiment is to be constructed at the CERN Neutrinos to Gran Sasso facility (CNGS). This will be the first experiment to demonstrate proton-driven plasma wakefield acceleration. The 400 GeV proton beam from the CERN SPS will excite a wakefield in a plasma cell several meters in length. To probe the plasma wakefield, electrons of 10–20 MeV will be injected into the wakefield following the head of the proton beam. Simulations indicate that electrons will be accelerated to GeV energies by the plasma wakefield. The AWAKE spectrometer is intended to measure both the peak energy and energy spread of these accelerated electrons. Results of beam tests of the scintillator screen output are presented, along with tests of the resolution of the proposed optical system. The results are used together with a BDSIM simulation of the spectrometer system to predict the spectrometer performance for a range of possible accelerated electron distributions.

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WEPMY025

iMPACT, Undulator-Based Multi-Bunch Plasma Accelerator

plasma, undulator, wakefield, electron

2609

O. Mete Apsimon, K. Hanahoe, G.X. Xia
UMAN, Manchester, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
B. Hidding
USTRAT/SUPA, Glasgow, United Kingdom
J.D.A. Smith
Tech-X, Boulder, Colorado, USA

Funding: This work is supported by the Cockcroft Institute Core Grant and STFC.
The accelerating gradient measured in laser or electron driven wakefield accelerators can be in the range of 10-100GV/m, which is 2-3 orders of magnitude larger than can be achieved by conventional RF-based particle accelerators. However, the beam quality preservation is still an important problem to be tackled to ensure the practicality of this technology. In this global picture, the main goals of this study are planning and coordinating a physics program, the so-called iMPACT, that addresses issues such as emittance growth mechanisms in the transverse and longitudinal planes through scattering from the plasma particles, minimisation of the energy spread and maximising the energy gain while benchmarking the milestones. In this paper, a summary and planning of the project is introduced and initial multi-bunch simulations were presented.

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WEPMY026

A Gas-filled Capillary Based Plasma Source for Wakefield Experiments

plasma, vacuum, high-voltage, experiment

2613

O. Mete Apsimon, K. Hanahoe, T.H. Pacey, G.X. Xia
UMAN, Manchester, United Kingdom

Funding: This work is supported by the University of Manchester Strategic Grant.
A plasma medium can be formed when a gas is discharged via an applied high voltage within a capillary tube. A high voltage discharge based plasma source for plasma wake- field acceleration experiment is being developed. Design considered a glass capillary tube with various inner radii. Glass was preferred to sapphire or quartz options to ease the machining. Electrodes will be attached to the tube using a sealant resistant to high vacuum conditions and baking at high temperatures. Each electrode will be isolated from the neighbouring one using nuts or washers from a thermoplastic polymer insulator material to prevent unwanted sparking outside of the tube. In this paper, general design considerations and possible working points of this plasma source are presented for a range of plasma densities from 1×10²⁰ to 1×10²² m^−3. Consideration was also given to plasma density diagnostic techniques due to critical dependence of accelerating gradient on plasma density.

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WEPMY027

Feasibility Study of Plasma Wakefield Acceleration at the CLARA Front End Facility

plasma, experiment, wakefield, accelerating-gradient

2617

K. Hanahoe, R.B. Appleby, Y. M. Li, T.H. Pacey, G.X. Xia
UMAN, Manchester, United Kingdom
B. Hidding
USTRAT/SUPA, Glasgow, United Kingdom
B. Kyle
University of Manchester, Manchester, United Kingdom
O. Mete Apsimon
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
J.D.A. Smith
Tech-X, Boulder, Colorado, USA

Funding: Cockcroft Institute Core Grant and STFC
Plasma wakefield acceleration has been proposed at the CLARA Front End (FE) facility at Daresbury Laboratory. The initial phase of the experiment will acceleration of the tail of a single electron bunch, and the follow-up experiment will study preserving a high quality beam based on a two-bunch acceleration scenario. In this paper, a concept for the initial experiment is outlined and detailed simulation results are presented.

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WEPMY037

Cold Model Cavity for 20-K Cryocooled C-band Photocathode RF Gun

cavity, gun, coupling, impedance

2635

T. Tanaka, M. Inagaki, R. Nagashima, K. Nakao, K. Nogami, T. Sakai, K. Takatsuka
LEBRA, Funabashi, Japan
M.K. Fukuda, T. Takatomi, N. Terunuma, J. Urakawa, M. Yoshida
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
A cryocooled 2.6-cell C-band photocathode RF gun is under development at Nihon University in collaboration with KEK. The RF characteristics of a pillbox-type 2.6-cell C-band RF cavity at 20 K were in agreement with the theoretical predictions. The result of the cold test for a cavity with the input coupler confirmed the same characteristics. Based on these results a refined cold model of the 20-K cryocooled photocathode RF gun has been designed using SUPERFISH and CST-STUDIO. The separation between the TM01 pi and the TM01 half-pi modes has been increased from 20 MHz to 52 MHz by extending the diameter of the cavity iris and reducing the disk thickness. The 2.6-cell structure has been modified from pillbox to ellipsoid-like type. The end-plate of the 0.6-cell cavity has a center hole for bead-pull measurements of the on-axis electric filed through the entire structure. Mounting of a photocathode assembly in the end-plate has not been considered, since the purpose is solely to measure the low-power and low-temperature RF characteristics. A new design for the input coupler has been employed. The cavity will be completed early in 2016.

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WEPMY038

Optimization of C-band RF Input Coupler as a Mode Converter for 20-K Cryocooled Photocathode RF Gun

cavity, gun, coupling, insertion

2638

T. Tanaka, M. Inagaki, R. Nagashima, K. Nakao, K. Nogami, T. Sakai, K. Takatsuka
LEBRA, Funabashi, Japan
M.K. Fukuda, T. Takatomi, N. Terunuma, J. Urakawa, M. Yoshida
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
Development of a cryocooled 2.6-cell C-band photocathode RF gun has been conducted at Nihon University in collaboration with KEK. An RF mode converter from square TE10 to circular TM01 mode has been employed as an RF input coupler that has a coupling coefficient of approximately 20 at 20 K to the 2.6-cell accelerating structure. In the previous design, the circular waveguide in the mode converter formed part of the accelerating cavity. After the cold test of the cavity completed in 2014, the coupler design was modified to work as a pure mode converter with a VSWR of 1 at 5712 MHz. From the design simulation using CST-STUDIO, the insertion loss in the converter is 0.2 %. The TM010 and TM011 modes excited in the circular waveguide were separated by several ten MHz from the accelerating frequency. The simulation has suggested that the amplitude of the transverse electric filed on the axis in the circular waveguide is reduced to approximately 2 % of that in the longitudinal direction.

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WEPMY040

Fabrication of Two Dimensional Nano-Scale Photocathode Arrays in Transparent Conductor for High Coherence Beam Generation

electron, laser, cathode, photon

2645

T. Shibuya
TIT, Tokyo, Japan
N. Hayashizaki
RLNR, Tokyo, Japan
M. Yoshida
KEK, Ibaraki, Japan

Electron beam quality for particle source of diffractometer is mainly characterized by transverse and longitudinal coherent length, beam current density and so on. In order to improve a transverse coherent length, it is practically essential to minimize electrons emission area size as small as possible. However, the size of photoemission area is limited by focused laser beam size on the surface of cathode, and the scale is several microns. Aim to get definite overlap between the focused laser and emitters for effective irradiation, as well as to realize generation of nano-scale size electron beam, nano-scale photocathode arrays in transparent conductor are essential. Therefore, I propose to fabricate the nano-scale emission area in replace of limiting the focused laser size on the photocathode for achieving high coherence beam. The fabrication process of this novel nano-scale emitter configuration and its fundamental properties are presented in this paper.

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WEPMY043

Parallel Particle Movement Simulation Algorithm Based on Heterogeneous Computing

GPU, hardware, controls, framework

2654

L.G. Zhang, L. Cao, K. Fan, J. Huang, K.F. Liu, W. Qi, J. Yang
HUST, Wuhan, People's Republic of China

Particle in cell (PIC) algorithm studies the self-consistent motion of multi-particle system by solving equations of particle dynamics, this algorithm is widely used to evaluate the nonlinear space charge effect of the high intensity or low energy beam. In order to reduce the random noise in the simulation, a huge number of particles should be traced, the process expends many computer hardware resources and a lot of computing time. Heterogeneous computing can greatly improve the efficiency of large quantities of the particle tracking by making full use of different types of computing resources. In this paper we give the algorithm which uses both CPU and GPU to trace the particles in electromagnetic field. The results show that the given algorithm increases the efficiency significantly.

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WEPOR006

Demonstration of CLIC Level Phase Stability using a High Bandwidth, Low Latency Drive Beam Phase Feedforward System at the CLIC Test Facility CTF3

kicker, hardware, optics, electronics

2673

J. Roberts, P. Burrows, G.B. Christian, C. Perry
JAI, Oxford, United Kingdom
A. Andersson, R. Corsini, P.K. Skowroński
CERN, Geneva, Switzerland
A. Ghigo, F. Marcellini
INFN/LNF, Frascati (Roma), Italy

Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu-CARD, grant agreement no.~227579.
The CLIC acceleration scheme, in which the RF power used to accelerate the main high energy beam is extracted from a second high intensity but low energy beam, places strict requirements on the phase stability of the power producing drive beam. To limit luminosity loss caused by energy jitter leading to emittance growth in the final focus to below 1%, 0.2 degrees of 12 GHz, or 50 fs, drive beam phase stability is needed. A low-latency phase feedforward correction with bandwidth above 17.5 MHz will be used to reduce the drive beam phase jitter to this level. The proposed scheme corrects the phase using fast electromagnetic kickers to vary the path length in a chicane prior to the drive beam power extraction. A prototype of this system has been installed at the CLIC test facility CTF3 to prove its feasibility. The latest results from the system are presented, demonstrating phase stabilisation in agreement with simulations given the beam conditions and power of the kicker amplifiers. Necessary improvements in the phase monitor performance and optics corrections made to remove the phase-energy dependence via R56 in order to achieve this level of stability are also discussed.

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WEPOR008

Development of a High Resolution Beam Position Monitor for NSRRC VUV/THz FEL

cavity, dipole, electron, coupling

2680

P.J. Kung, K.C. Leou
NTHU, Hsinchu, Taiwan
W.K. Lau, A.P. Lee
NSRRC, Hsinchu, Taiwan

Beam position monitors (BPM) have been widely used on linear colliders and free electron lasers for beam-based alignment and feedback systems. A laser driven photo-injector system has been constructed in NSRRC. This injector has the capability to deliver short relativistic electron beam at high peak current for novel light source R&D. A 2.4 GHz BPM that can be used for high precision beam position measurement has been designed. The BPM were modified to separate frequency between the horizontal and vertical dipole signals, as well as a reduction of the monopole signal. The design has been simulated by CST. A prototype has been built for verification of theoretical predictions. Microwave bench measurement has been made to compare with the computer simulation results. The progress of our work will be presented in this paper.

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WEPOR009

Intra-beam IP Feedback Studies for the 380 GeV CLIC Beam Delivery System

luminosity, feedback, ground-motion, kicker

2683

R.M. Bodenstein, P. Burrows, J. Snuverink
JAI, Oxford, United Kingdom
F. Plassard
CERN, Geneva, Switzerland

In its currently-envisaged initial stage, the Compact Linear Collider (CLIC) will collide beams with a 380 GeV center of mass energy. To maintain the luminosity within a few percent of the design value, beam stability at the interaction point (IP) must be controlled at the sub-nanometer level. To help achieve such control, use of an intra-pulse IP feedback system is planned. With CLIC's very short bunch spacing of 0.5 ns, and nominal pulse duration of 176 ns, this feedback system presents a significant technical challenge. Furthermore, as part of a study to optimize the design of the beam delivery system (BDS), several L* configurations have been studied. In this paper, we will review the IP feedback simulations for the 380 GeV machine for two L* configurations, and compare luminosity recovery performance with that of the original L* configuration in the 3 TeV machine.

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WEPOR011

Lattice Matching with Elegant at ELSA

closed-orbit, dipole, lattice, quadrupole

2690

J.-P. Thiry, W. Hillert
ELSA, Bonn, Germany

The electron stretcher ring ELSA provides a beam of polarized electrons of up to 3.2 GeV energy. To preserve the initial degree of polarization, several depolarizing resonances have to be compensated during the fast energy ramp of 6 GeV/s. Beam depolarization, caused by crossing these resonances is studied using comprehensive numerical calculations. These depend essentially on a precise model of the actual magnetic field distributions, explicitly taking into account misalignments. Hence it is necessary to match the theoretical lattice to the actual accelerator. In a first step the alignment of all magnets has been examined and improved. This was done by using standard survey equipment and precise electronic spirit levels. In a second step the concept of response matrix fitting is used for further, beam based, lattice matching. Particle tracking and optics calculations are carried out using elegant, a fully 6D accelerator toolbox. Lattice matching is done by repeatedly calling elegant and utilizing a modified Levenberg-Marquardt optimizer. In this contribution we will describe our lattice fitting implementation.

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WEPOR024

HPGe Detector Application on Monitoring Environmental Samples around the Accelerator

detector, photon, software, monitoring

2725

Y.D. Ding, Z.J. Ma, Q.B. Wang, M.Y. Yan, Q.J. Zhang
IHEP, Bejing, People's Republic of China

Massive experimental works are aimed to clarify the structure of detector including CT with X ray machine, determining the thickness of dead layer with collimating radioactive source and ect. Measuring structure and size of the detector by X-ray computed tomography, measur-ing the dead layer thickness of detector's front surface and side surface though collimated point source method, scanning the dead layer distribution of the entire detec-tor. A finite element analysis software name CST is used to simulate electric field distribution of the HPGe detec-tor. Calibrating the efficiency of HPGe detector by means of point source and soil standard matter, A Monte Carlo software called MCNP is used to simulate detector effi-ciency preliminarily according to the structure parame-ters of the factory, optimizing and verifying simulated results on the basis of measured results. At last, the com-parison of the simulated and the experimental data showed very good agreement.

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WEPOR043

End-to-end FEL Beam Stability Simulation Engine

cavity, linac, software, cryomodule

2768

C. Serrano, L.R. Doolittle
LBNL, Berkeley, California, USA
D.S. Driver, B. Patel, A.F. Queiruga, Z. Zaky
UCB, Berkeley, USA
Q. Llimona
UPF, Barcelona, Spain

Funding: Work supported by U.S. Department of Energy
During the design, commissioning and operation of a linac-driven Free Electron Laser (FEL) it is important to have a good understanding of the implications of accelerator design choices on beam figures of merit. This simulation engine combines a full state-space model of the RF system (High-Power Amplifier, RF cavities, LLRF controllers, etc.), a characterization of beam properties such as energy, bunch length and arrival time as electrons propagate through the Linac and beam-based feedback. The combination of these models with the ability to introduce both correlated and uncorrelated noise sources at any point of the machine, allows for a complete transposition of noise sources to beam performance parameters, including frequency dependence, in order to analyze implications of accelerator design choices in a simulation environment.

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WEPOR049

Jupyterhub at the ESS. An Interactive Python Computing Environment for Scientists and Engineers

software, controls, monitoring, site

2778

L. Fernández, R. Andersson, H. Hagenrud, T. Korhonen, E. Laface
ESS, Lund, Sweden
B. Zupanc
Cosylab, Ljubljana, Slovenia

The European Spallation Source will be the world's most powerful neutron source, once its construction is finished. In order to design, build and operate this complex machine many different software components and frameworks will be needed. One of those is Jupyterhub, a scripting environment for data analysis, scientific computing and physics simulations. Jupyterhub is a multiuser version of the IPython notebook (Jupyter) that can be deployed in a centralized server; It provides centralized authentication, centralized deployment, promotes collaboration and provides access to the most advanced libraries for data cleaning and transformation, simulation and statistics. At the Integrated Controls System Division a customized version of Jupyterhub was deployed, providing sandboxed environments to users using Docker containers. Among other characteristics of this installation we can find: clustering, load balancing, A/B testing, Amazon Web Services integration, nbviewer and OpenXAL integration.

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WEPOR051

Second Generation LHC Analysis Framework: Workload-based and User-oriented Solution

experiment, framework, factory, data-analysis

2784

S. Boychenko, C. Aguilera-Padilla, M.A. Galilée, J.C. Garnier, A.A. Gorzawski, K.H. Krol, J. Makai, M. Osinski, M.C. Poeschl, T.M. Ribeiro, A. Stanisz, M. Zerlauth
CERN, Geneva, Switzerland
M.Z. Rela
University of Coimbra, Coimbra, Portugal

Consolidation and upgrades of accelerator equipment during the first long LHC shutdown period enabled particle collisions at energy levels almost twice higher compared to the first operational phase. Consequently, the software infrastructure providing vital information for machine operation and its optimisation needs to be updated to keep up with the challenges imposed by the increasing amount of collected data and the complexity of analysis. Current tools, designed more than a decade ago, have proven their reliability by significantly outperforming initially provisioned workloads, but are unable to scale efficiently to satisfy the growing needs of operators and hardware experts. In this paper we present our progress towards the development of a new workload-driven solution for LHC transient data analysis, based on identified user requirements. An initial setup and study of modern data storage and processing engines appropriate for the accelerator data analysis was conducted. First simulations of the proposed novel partitioning and replication approach, targeting a highly efficient service for heterogeneous analysis requests, were designed and performed.

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WEPOR052

Emittance Measurements in Low Energy Storage Rings

emittance, antiproton, electron, optics

2788

C.P. Welsch, J.R. Hunt, J. Resta-López
Cockcroft Institute, Warrington, Cheshire, United Kingdom
J.R. Hunt, J. Resta-López, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: Work supported by the EU under grant agreement 624854 and the STFC Cockcroft Institute Core Grant No. ST/G008248/1.
The development of the next generation of ultra-low energy antiproton and ion facilities requires precise information about the beam emittance to guarantee optimum performance. In the Extra-Low ENergy Antiproton storage ring (ELENA) the transverse emittances will be measured by scraping. However, this diagnostic measurements faces several challenges: non-zero dispersion and systematic errors due to diffusion processes, such as intra-beam scattering, and the speed of the scraper with respect to the beam revolution frequency. In addition, the beam distribution will likely be non-Gaussian. Here, we present algorithms to efficiently address the emittance reconstruction in presence of the above effects, and present simulation results for the case of ELENA. We also discuss the feasibility of using alternative non-invasive techniques for profile and emittance measurements.

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WEPOW036

Bunch Length Measurements with Passive Harmonic Cavities for Uniform Fill Patterns in a 100 MHz RF System

storage-ring, impedance, cavity, lattice

2914

T. Olsson, S.C. Leemann, P. Lilja
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV facility includes two storage rings operated at 1.5 GeV and 3 GeV. Both rings make use of a 100 MHz RF system and are designed to operate with a uniform multibunch fill pattern as well as employ passive harmonic cavities to damp instabilities and increase Touschek lifetime. Recently, a discussion on timing modes at the MAX IV storage rings has been initiated by the user community. This implies operating the rings with other fill patterns than the originally planned multibunch mode and therefore detailed studies of the performance of the harmonic cavities are of interest. This paper presents bunch length measurements at the 100 MHz MAX II storage ring for uniform fill patterns. The purpose of the measurements was to evaluate the employed measurement method and simulation codes for future studies of fill patterns in the MAX IV storage rings.

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WEPOW037

Bunch Length Measurements with Passive Harmonic Cavities for Non-uniform Fill Patterns in a 100 MHz RF System

storage-ring, cavity, beam-loading, feedback

2918

T. Olsson, S.C. Leemann, P. Lilja
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV facility includes two storage rings operated at 1.5 GeV and 3 GeV, which are both designed to operate with a uniform, multibunch fill pattern. Both rings have a 100 MHz RF system and employ passive harmonic cavities to damp instabilities and increase Touschek lifetime. Recently, a discussion on timing modes at the MAX IV storage rings has been initiated by the user community. Creating opportunities for timing experiments implies operating the rings with other fill patterns than the planned multibunch mode. Such operation can, however, cause transient effects in the passive harmonic cavities which affect the performance of the machine. It is therefore of interest to study the effect on the beam when operating with non-uniform fill patterns. This paper presents bunch length measurements at the 100 MHz MAX II storage ring for fill patterns with gaps. The purpose of the measurements was to evaluate the employed measurement method and simulation codes for future studies of various alternate fill patterns in the MAX IV storage rings.

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WEPOW053

CESR Lattice for Two Beam Operations with Narrow Gap Undulators at CHESS

undulator, lattice, injection, operation

2968

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

Funding: Work was supported by NSF DMR-0936384 and NSF DMR-1332208.
CESR has operated as a dedicated light source since the conclusion of colliding beam program in 2008. Two undulators with a 6.5mm-vertical gap were installed in Fall 2014, replacing a wiggler in the sextant of CESR that is the home to all CHESS beam lines. In order to operate narrow gap undulators with two beams, CESR pretzel lattice was redesigned so that e^- and e⁺ orbits are coincident in one machine sextant but separated in return arcs. In particular both e^- and e⁺ orbits are on axis through undulators. This "arc-pretzel" lattice has been the basis for undulator operation. To better understand the beam dynamics and improve machine performance, we developed many simulation tools: undulator modeling, injection tracking, etc. With installation of an additional quadrupole near undulators, the CESR lattice will be further modified with a low beta waist in the insertion devices, allowing a more than two fold reduction of local beta functions. This reduction is anticipated to mitigate the effects of small aperture and undulator field errors and to enhance the xray brightness. The characterization of the lattice will be compared with measurements of injection efficiency, tune scans, etc.

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WEPOW057

Spectral Analysis of Turn-by-Turn Data

betatron, storage-ring, collective-effects, Windows

2979

J. Choi
BNL, Upton, Long Island, New York, USA

Funding: DOE contract No: DE-SC0012704
With the recent technical developments, it is now popular to get the turn-by-turn data for the storage ring. Even though response matrix based analysis, like LOCO, have strong advantages in lattice analysis, the turn-by-turn data analysis is quite attractive because it takes very short time in data acquisition and many effective analyzing methods have been developed. Basically, such analysis requires accurate estimation of peaks of frequency spectra with high resolution. In this paper, we review the various accuratenesses of such estimations depending on processes using exact sinusoidal data and apply the end-matching method to simulation and measurement.

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WEPOY002

A Time Domain Analysis Method for RF Noise

cavity, experiment, beam-loading, LLRF

2994

L. Lin, B. Du, G. Huang, Y.T. Liu
USTC/NSRL, Hefei, Anhui, People's Republic of China

A time domain analysis method is developed for the calculation of the longitudinal oscillations caused by the RF noise in the storage ring. This method is based on the impulse response model, and it could calculates the change of transient field caused by beam oscillation and RF noise turn by turn. By means of discrete spectrum analysis, the spectrum of the beam is obtained. According to this analysis method, we developed a simulation pro-gram. The synchronous oscillation of the excited by high RF source with a phase modulation is predicted in this program, and the corresponding experimental measure-ments are carried out on HLS II. The fitting results are in agreed with the experimental measurements.

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WEPOY004

Integrated Green Function for Charged Particle moving along Bending Orbit

radiation, synchrotron, synchrotron-radiation, collider

2997

K. Ohmi, S. Chen
KEK, Ibaraki, Japan
H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

Electro-magnetic field for moving charged particle is given by Liennard-Wiechert potential. The field contains high frequency component corresponding to synchrotron light, ω=3cγ³/(2ρ). The frequency is too high to study beam behavior generally. Green function integrated over beam distribution and/or over in a region σ_x/n_x× σ_y/n_y× σ_z/n_z (n_xyz ∼ 10) is useful to study instability and emittance growth of the beam. The green function is regarded as the wake field for coherent synchrotron radiation in three dimension space.

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WEPOY007

Simulation of Electromagnetic Scattering Through the E-XFEL Third Harmonic Cavity Module

cavity, HOM, dipole, factory

3001

N.Y. Joshi, R.M. Jones
UMAN, Manchester, United Kingdom
N. Baboi, L. Shi
DESY, Hamburg, Germany

Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 31245. N.~Y.~Joshi receives additional funding from The Cockcroft Institute of Science and Technology.
The European-XFEL is being fabricated in Hamburg to serve as an X-ray Free Electron Laser (FEL) light source. The electron beam will be accelerated through linacs consisting of 1.3 GHz superconducting cavities along a length of 2.1 km. In addition, third harmonic cavities will improve the quality of the beam by linearising the field profile and hence reducing the energy spread. There are eight 3.9 GHz cavities within a single module AH1 of E-XFEL. The beam-excited electromagnetic (EM) field in these cavities can be decomposed into a series of eigenmodes. These modes are, in general, not cut-off between one cavity and the next, as they are able to couple to each other throughout the module. Here for the first time, we evaluate components of the scattering matrix for module AH1. This is a computationally expensive system, and hence we employ a Generalized Scattering Matrix (GSM) technique to allow rapid computation with reduced memory requirements. Verification is provided on reduced structures, which are compared to finite element mesh-based codes. The mode spectrum for the dipole bands of interest in an eight-cavity chain have been calculated and external Q factors for the modes are derived.

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WEPOY009

Simulation Study of Emittance Growth from Coulomb Explosion in a Charge Separator System After Stripping

emittance, electron, space-charge, ion

3005

M. Droba, O. Meusel, U. Ratzinger
IAP, Frankfurt am Main, Germany

Funding: BMBF-05P15RFRBA
A computer 3D particle-in-cell (PIC) simulation is used to examine the emittance growth of an intense heavy ion beam after a charge stripper. Multi-species dynamics of the bunched uranium beam with various charge states and including compensation electrons will be presented. The rms-emittance growth shows different behaviour in the horizontal, vertical and longitudinal planes, dependent on initial conditions, like a bunch size, beam current and phase space ellipse orientation. An optimization of initial parameters is therefore crucial for a successful and efficient post-acceleration. The role of the separation system and of co-moving electrons will be discussed for the example of the GSI-Unilac.

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WEPOY010

Bunch Compression at the Recirculation Loop of the Compact ERL

linac, optics, electron, acceleration

3008

M. Shimada, K. Harada, Y. Honda, T. Miyajima, N. Nakamura, T. Obina, R. Takai, A. Ueda
KEK, Ibaraki, Japan

The compact Energy Recovery Linac (cERL) has been operated as a test facility for the future light-source since 2013. One of the targets of the beam commissioning of this winter is demonstration of bunch compression. The bunch has energy chirp in longitudinal direction by off crest acceleration and the bunch length is compressed in non-isochronous arc section. The short electron bunch is spread in the return arc to suppress the energy spread at the main beam dump. Four sextupole magnets were installed in two arcs in November 2015 to correct the squared term induced by RF curvature. The best position was determined by the beam tracking by elegant including Coherent Synchrotron Radiation (CSR) wake. The bunch length is measured by OTR in the south straight section just after the first arc. We present the demonstration of the bunch compression in this report.

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WEPOY015

Longitudinal Bram Dynamics at Rf-Compressor

gun, space-charge, electron, brightness

3011

A.V. Andrianov
BINP SB RAS, Novosibirsk, Russia

Nowadays the usage of charged particle beams for study of nature became widespread. Modern experiments are require particle beams with duration around hundreds femtosecond. Relatively simple and cheap method of production such pulses is using RF-gun with photocathode and then the special insertion device which compress the beam. The paper described the RF-compressor for the electron beam. In result of work was obtained a device configuration. Electromagnetic field configuration and distribution were simulated for the configuration. Beam dynamics was computed in this field distribution. Incoming beam parameters are following: beam length is 1-5ps, beam charge is 0.1-2pC and energy is 3MeV. Output beam duration was compressed to less than 150fs. Influence of RF-compressor at beam parameters was estimated.

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WEPOY016

Use of Nonuniform Magnets for Emittance Reduction

emittance, lattice, dipole, radiation

3014

E.B. Levichev, G.N. Baranov, S.V. Sinyatkin
BINP SB RAS, Novosibirsk, Russia

We study a theoretical minimum emittance (TME) for a non-uniform bending magnet including a three-step bend (sandwich magnet), a dipole with linear ramp of the bend-ing radius and the same but with a central segment of constant field. We derive expression for the minimum emittance and expand it into a power series with respect to the bending angle. A zero-order term naturally gives the uniform magnet TME while higher-order terms are responsible for the emittance reduction. Theoretical re-sults are verified by numerical simulation.

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WEPOY018

Study on Electron Beam Transverse Emittance at the Linac-based THz Laboratory in Thailand

emittance, quadrupole, electron, linac

3017

K. Kosaentor
IST, Chiang Mai, Thailand
S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand

This research focuses on simulation of transverse emittance of electron beams, which are produced from a thermionic RF-gun at the Plasma and Beam Physics (PBP) Research Facility, Chiang Mai University (CMU). The RF-gun is used to together with an alpha magnet for serving as the electron injector system for the PBP linac-based THz source. The quadrupole scan technique is utilized to measure the transverse beam emittance at the entrance of the alpha magnet. The experimental setup consists of quadrupole magnets with a maximum gradient of 7.01 T/m, a drift tube, and a movable fluorescent screen station. Beam dynamic simulations by using the computer codes PARMELA and ELEGANTare performed to track electrons from the cathode to the experimental station. In this contribution, the emittance values from simulations including the space charge effects will be reported.
This work has been supported by the CMU Junior Research Fellowship Program, Department of Physics and Material Science, Faculty of science, Chiang Mai University.

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WEPOY025

High Power RF Generation From a W-Band Corrugated Structure Excited by a Train of Electron Bunches

wakefield, electron, experiment, acceleration

3040

D. Wang, C.-X. Tang
TUB, Beijing, People's Republic of China
S.P. Antipov, C.-J. Jing, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, D.S. Doran, W. Gai, G. Ha, G. Ha, W. Liu, J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA
V.A. Dolgashev
SLAC, Menlo Park, California, USA

We report on the generation of multi-megawatt peak RF power at 91textGHz, using an ultrarelativistic electron bunch train to excite electromagnetic fields in a high-impedance metallic corrugated structure. This device can be used as a power source for high gradient acceleration of electrons. To achieve precise control of the wakefield phase, a long range wakefield interferometry method was developed in which the RF energy due to the interference of the wakefields from two bunches was measured as a function of the bunch separation.

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WEPOY026

Simulation and Measurement of the Beam Breakup Instability in a W-band Corrugated Structure

wakefield, dipole, electron, radiation

3044

D. Wang, C.-X. Tang
TUB, Beijing, People's Republic of China
S.P. Antipov, C.-J. Jing, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, D.S. Doran, W. Gai, G. Ha, W. Liu, J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA

The corrugated wakefield structure has wide application in electron beam energy manipulation and high frequency RF radiation generation. The transverse wakefield which cause beam breakup (BBU) instability is excited when the drive beam is not perfectly centered through the structure. Here we report on the numerical and experimental investigation of the BBU effect in a W-band corrugated structure, for both cases of short range wakefield and long range wakefield. In the numerical part we develop a point to point (P2P) code that allows rapid and efficiency simulations of the beam dynamics effect by wakefield, which is based on the the particle-wake function coupled dynamics equation of motion. And the experimental measurements of BBU effect are found to be in good agreement with the simulations.

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WEPOY030

First BTF Measurements at the Large Hadron Collider

octupole, injection, betatron, damping

3051

C. Tambasco, A. Boccardi, X. Buffat, K. Fuchsberger, M. Gąsior, R. Giachino, T. Lefèvre, T.E. Levens, T. Pieloni, M. Pojer, B. Salvachua, M. Solfaroli Camillocci
CERN, Geneva, Switzerland
J. Barranco, C. Tambasco
EPFL, Lausanne, Switzerland

During the Run I in 2012, several instabilities have been observed at the Large Hadron Collider (LHC) during the Betatron squeeze. The predictions of instability thresholds are based on the computation of the beam Landau damping by calculating the Stability Diagrams (SD). These instabilities could be explained by a deterioration of the SD due to beam-beam resonance excitation which could change the particle distributions. Beam Transfer Functions (BTF) provide a measurement of the Stability Diagram. The BTFs are sensitive to the particle detuning with amplitude as well as to the particle distributions therefore they represent a powerful tool to understand experimentally the stability of beams during the LHC operational cycle. First BTF measurements at the LHC are presented for different machine configurations and settings and compared to predictions.

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WEPOY033

Space Charge Compensation in Low Energy Beam Lines

space-charge, proton, electron, solenoid

3055

F. Gérardin, N. Chauvin, D. Uriot
CEA/IRFU, Gif-sur-Yvette, France
M.A. Baylac, D. Bondoux, F. Bouly
LPSC, Grenoble Cedex, France
A. Chancé, O. Napoly, N. Pichoff
CEA/DSM/IRFU, France

The dynamics of a high intensity beam with low energy is governed by its space-charge forces which may be responsible of emittance growth and halo formation due to their non-linearity. In a low energy beam transport (LEBT) line of a linear accelerator, the propagation of a charged beam with low energy causes the production of secondary particles created by the interaction between the beam and the background gas present in the accelerator tube. This phenomenon called space-charge compensation is difficult to characterize analitically. In order to obtain some quantitative to characterize the space-charge compensation (or neutralization), numerical simulations using a 3D PIC code have been implemented.

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WEPOY034

Latest Improvements of OPAL

space-charge, dipole, electromagnetic-fields, linac

3058

C.J. Metzger-Kraus, M. Abo-Bakr, B.C. Kuske
HZB, Berlin, Germany
A. Adelmann
PSI, Villigen PSI, Switzerland

OPAL (Object Oriented Parallel Accelerator Library) is an open source, C++ based tool for charged particle tracking in large accelerator structures and beam lines including 3D space charge, particle matter interaction and FFAG capabilities. The careful parallel design makes it possible to tackle large and complex problems, in a reasonable time frame. The current code status and latest program improvements and upgrades are introduced. One of the provided flavors, OPAL-T, was, so-far, used for relatively simple lattices and was not well suited for more complicated arrangements of elements. One of the major upgrades is the possibility to place elements in 3D space, giving the user a better control in absolute element positioning. The old input format with relative positioning is still supported. We show results of the BERLinPro lattice and compare it with results obtained with elegant.

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WEPOY035

Free Electron Laser Simulation Tool Based on FDTD/PIC in the Lorentz Boosted Frame

FEL, undulator, radiation, electron

3061

A. Yahaghi, A. Fallahi, F.X. Kärtner
CFEL, Hamburg, Germany
F.X. Kärtner
MIT, Cambridge, Massachusetts, USA

Funding: Alexander von Humboldt-Foundation European Research Council(ERC)
Free Electron Lasers (FELs) are promising sources capable of generating electromagnetic waves in the whole spectrum. Therefore, it is crucial and additionally very useful to develop sophisticated though complete simulation tools. This goal is mainly motivated by our research focus on the development of compact X-ray sources based on radiation in optical undulators. The currently existing softwares are usually written to tackle special cases with particular approximations, such as 1D FEL theory, steady state, slow wave and forward wave approximation, wiggler-averaged electron motion and slices approximation. Many of the above approximations are hardly valid when sub-femtosecond bunches interact with intense optical lasers. The presented software aims the analysis of the FEL interaction without considering any of the above approximations. The developed tool apparently suffers from long computation times but offers a more accurate picture on the radiation process. In order to overcome the problem of multidimensionality, we exploit Lorentz boosted coordinate system and implement Finite Difference Time Domain (FDTD) method combined with Particle in Cell (PIC) simulation in this frame.

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WEPOY037

Optimization of THz Radiation Pulses at FLUTE

electron, radiation, gun, linac

3067

M. Yan, A.-S. Müller, M.J. Nasse, M. Schuh, M. Schwarz
KIT, Karlsruhe, Germany

The accelerator test facility FLUTE (Ferninfrarot Linac Und Test Experiment) will allow research and development in electron accelerator technology as well as photon science. Electron bunches of durations in the femtosecond range will be provided to generate intense THz radiation. Start-to-end simulation of the accelerator has been performed with the bunch length as the optimization objective. Based on the resulting charge distribution the expected THz field properties can be calculated. In this paper we combine the two tools and present first results.

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WEPOY044

Review of CPU and GPU Faddeeva Implementations

timing, GPU, interface, space-charge

3090

A. Oeftiger, R. De Maria, L. Deniau, K.S.B. Li, E. McIntosh, L. Moneta
CERN, Geneva, Switzerland
A. Aviral
BITS Pilani, Pilani, India
S. Hegglin
ETH, Zurich, Switzerland
A. Oeftiger
EPFL, Lausanne, Switzerland

Funding: CERN, Doctoral Studentship EPFL, Doctorate
The Faddeeva error function is frequently used when computing electric fields generated by two-dimensional Gaussian charge distributions. Numeric evaluation of the Faddeeva function is particularly challenging since there is no single expansion that converges rapidly over the whole complex domain. Various algorithms exist, even in the recent literature there have been new proposals. The many different implementations in computer codes offer different trade-offs between speed and accuracy. We present an extensive benchmark of selected algorithms and implementations for accuracy, speed and memory footprint, both for CPU and GPU architectures.

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WEPOY045

Benchmarking the Beam Longitudinal Dynamics Code BLonD

impedance, synchrotron, feedback, injection

3094

H. Timko, J. F. Esteban Müller, A. Lasheen, D. Quartullo
CERN, Geneva, Switzerland

The relatively recent Beam Longitudinal Dynamics code BLonD has already been applied to a wide range of studies for all present CERN synchrotrons. Its application area ranges from studies of RF manipulations, over single and multi-bunch interactions with impedance, to the action of feedback loops and RF noise. In this paper, we present benchmarks and comparisons with measurements, theory, or other codes, which have increased greatly the trust in the code. Tests related to bunch-to-bucket transfer, feedback loops, diffusion due to noise injection, as well as collective effects, are presented.

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WEPOY046

Beam Delivery Simulation: BDSIM - Automatic Geant4 Models of Accelerators

collider, background, detector, radiation

3098

L.J. Nevay, S.T. Boogert, L.C. Deacon, S.M. Gibson, R. Kwee-Hinzmann, W. Shields, J. Snuverink
JAI, Egham, Surrey, United Kingdom
H. Garcia
CERN, Geneva, Switzerland

Beam Delivery Simulation (BDSIM) is a program that uses a suite of high energy physics software including Geant4, CLHEP & ROOT, that seamlessly tracks particles through accelerators and detectors utilising the full range of particles and physics processes from Geant4. BDSIM has been used to simulate linear colliders such as the International Linear Collider (ILC) and more recently, circular colliders such as the Large Hadron Collider (LHC). The latest developments including improved geometry modelling; external geometry support; process biasing; and a new event display are presented. A significantly revised and improved accompanying tool chain is presented comprising of a series of Python utilities that allow efficient and automatic preparation of models. Furthermore, a library for both ROOT and Python that provides powerful analysis and event viewing after simulation is demonstrated.

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WEPOY047

LHC Collimation and Energy Deposition Studies Using Beam Delivery Simulation (BDSIM)

collimation, optics, proton, beam-losses

3101

L.J. Nevay, S.T. Boogert, S.M. Gibson, R. Kwee-Hinzmann
JAI, Egham, Surrey, United Kingdom
R. Bruce, H. Garcia, S. Redaelli
CERN, Geneva, Switzerland

Beam Delivery Simulation (BDSIM) is a program that uses a suite of high energy physics software including Geant4, CLHEP & ROOT, that seamlessly tracks particles through accelerators and detectors utilising the full range of particles and physics processes from Geant4. A comparison of the collimator cleaning efficiency and energy deposition throughout the full length of the Large Hadron Collider (LHC) with the established SixTrack simulations of the CERN collimation group is presented. The propagation of the full hadronic showers from collimators provides unparalleled detail in energy deposition maps and these are compared with the data from beam loss monitors that measure radiation outside the magnet body.

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WEPOY050

A Differential Algebraic Framework for the Fast Indirect Boundary Element Method

multipole, space-charge, framework, controls

3107

A.J. Gee, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA
B. Erdelyi
ANL, Argonne, USA

Beam physics at the intensity frontier must account for the beams' realistic surroundings on their dynamics in an accurate and efficient manner. Mathematically, the problem can be expressed as a Poisson PDE with given boundary conditions. Commonly, the Poisson boundary value problem is solved locally within many volume elements. However, it is known the PDE may be re-expressed as indirect bound- ary integral equations (BIE) which give a global solution*. By solving the BIEs on M surface elements, we arrive at the indirect boundary element method (iBEM). Iteratively solving this dense linear system of form Ax = b scales like (m_iterations M² ). Accelerating with the fast multipole method (FMM) can reduce this to O(M) if m_iterations << M. For N evaluation points, the total complexity would be O(M) + O(N) or O(N) with N = M. We have implemented a constant element version of this fast iBEM based on our previous work with the FMM in the differential algebraic (DA) framework**. This implementation is to illustrate the flexibility and accuracy of our method. A future version will focus on allowing for higher order elements.
* Sauter, S. and C. Schwab. Boundary Element Methods (2011)
** Abeyratne, S., S. Manikonda, and B. Erdelyi. "A novel differential algebraic adaptive fast multipole method." IPAC 2013: 1055-1057.

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THOAA01

Identification of Intra-bunch Transverse Dynamics for Model-Based Control Purposes at CERN Super Proton Synchrotron

controls, feedback, synchrotron, proton

3145

O. Turgut, J.E. Dusatko, J.D. Fox, C.H. Rivetta
SLAC, Menlo Park, California, USA
S.M. Rock
Stanford University, Stanford, California, USA

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program (LARP). Research supported by FP7 HiLumi LHC http://hilumilhc.web.cern.ch
The high luminosity upgrade plan for the LHC (HiLumi-LHC) increases the bunch intensity and the ultimate intensities require mitigation of possible intra-bunch instabilities in the SPS. Feedback systems can stabilize intra-bunch dynamics. Model based control has promise to stabilize intra-bunch dynamics but it requires a reduced order model which captures the most significant intra-bunch dynamics. We present methods for the estimation of a multi-input multi-output (MIMO) reduced order model of intra-bunch dynamics based on data generated by nonlinear macro particle simulations (CMAD, HeadTail). These linear models are used to design optimal model-based controllers. We evaluate the effectiveness of the MIMO model-based controllers for future high intensity beam conditions within the nonlinear macro particle simulations. We highlight the use of these techniques to stabilize intra-bunch motion and as an important beam dynamics measurement technique.

Slides THOAA01 [10.146 MB]

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THYA01

Advanced Concepts and Methods for Very High Intensity Linacs

emittance, space-charge, diagnostics, focusing

3155

P.A.P. Nghiem, N. Chauvin, D. Uriot
CEA/DSM/IRFU, France
M. Comunian
INFN/LNL, Legnaro (PD), Italy
C. Oliver
CIEMAT, Madrid, Spain
W. Simeoni
IF-UFRGS, Porto Alegre, Brazil
M. Valette
CERN, Geneva, Switzerland

For very high intensity linacs, both beam power and space charge should be taken into consideration for any analysis of accelerators aiming at comparing their performances and pointing out the challenging sections. As high beam power is an issue from the lowest energy, careful and exhaustive beam loss predictions have to be done. High space charge implies lattice compactness making the implementation of beam diagnostics very problematic, so a clear strategy for beam diagnostic has to be defined. Beam halo becomes no longer negligible, and it plays a significant role in the particle loss process. Therefore, beam optimization must take the halo into account and beam characterization must be able to describe the halo part in addition to the core one. This presentation discusses advanced concepts and methods for beam analysis, beam loss prediction, beam optimization, beam diagnostic and beam characterization especially dedicated to very high intensity accelerators.

Slides THYA01 [6.177 MB]

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THOBA02

Space Charge Induced Collective Modes and Beam Halo in Periodic Channels

space-charge, focusing, resonance, emittance

3165

C. Li, Zh.C. Liu, Q. Qin, Y.L. Zhao
IHEP, Beijing, People's Republic of China

Funding: This work is supported by the Ministry of Science and Technology of China under Grant No. 2014CB845501.
The collective mode instabilities of periodically focused high intensity beams based on the Vlasov-Poisson equation are investigated both analytically and numerically. It is found that the broadened collective stop bands resulting from space charge induced structure resonance in long periodic channels predict well the areas where the rms emittance growth accompanied with n-fold phase space structure (beam halo) would take place. We believe that the formed beam halo, which is depicted in action-angle frame, could be understood as a side-effect of the collective beam mode.

Slides THOBA02 [4.704 MB]

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THOBA03

Start-to-end Calculations and Trajectory Correction for BERLinPro

laser, linac, space-charge, timing

3167

B.C. Kuske, C.J. Metzger-Kraus
HZB, Berlin, Germany

Funding: Work funded by the Bundesministerium für Bildung und Forschung, Land Berlin and grants of the Helmholtz Association
BERLinPro is an ERL project under construction at the Helmholtz-Zentrum Berlin, with the goal to illuminate the challenges and promises of a high brightness 100 mA superconducting RF gun in combination with a 50 MeV return loop and energy recovery. Latest changes to the optics code OPAL allow for the first time to perform start-to-end tracking studies including space charge in a single run, without switching between codes. This opens the way to apply correction schemes to displaced trajectories in the complete machine and to study the effect of jitter sources, including the space charge dominated injector, on the machine performance parameters. Trajectory correction is discussed. Jitter is studied with respect to its potential impact on the recovery process and parameter changes before the dump.

Slides THOBA03 [5.903 MB]

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THPMB021

Design of the Magnets of the Far-Infrared FEL Project at NSRL

dipole, quadrupole, FEL, electron

3269

T.L. He, H. Xu, W. Xu, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: National Natural Science Foundation of China (10875118); National Natural Science Foundation of China (11375176)
This paper describes the magnetic design of the magnets of the far-infrared free electron laser at NSRL, including dipole magnets and quadrupole magnets with limited installing space. The dipoles are of three different effective lengths and strengths. All the magnets are designed and optimized by using POSSION and OPERA-3D. The end shimming and chamfer are modeled and fully determined by 3D simulation to meet the field uniformity requirement. The design consideration and simulation results are presented in detail.

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THPMB024

Error Analysis for the Lattice of FELiChEM

FEL, undulator, lattice, emittance

3278

S. Huang, Z.G. He, W. Xu, S.C. Zhang, T. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

FELiChEM is a new experimental facility under construction at University of Science and Technology of China (USTC).The facility consists of the middle-infrared (MID-FEL) beam line for 2.5-50 um and the Far-infrared (FAR-FEL) beam line for 40-200um. To achieve the design FEL performance of IR-FEL, the beam with 30 mm-mrad emittance, 5 ps rms length and 1nC bunch charge is required. We conduct error analysis in order to evaluate the tolerances of machine parameters and alignments. In this paper, we simulate the orbit corrections and emittance growth under exist of misalignments and strength errors of magnets. The simulation results show that the trajectory errors can be corrected to mm levels in the whole lattice and the emittance increase is acceptable. At the entrance of undulator, the position and angular errors can be corrected very well. So the trajectory can be controlled in the undulator to meet the requirement of FEL.

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THPMB028

Beam Optics of 180-degree Bending Section including a Charge Stripper

linac, optics, sextupole, acceleration

3291

J.-H. Jang, H. Jin, J. Song
IBS, Daejeon, Republic of Korea

Funding: This work was supported by the Rare Isotope Science Project of Institute for Basic Science funded by Ministry of Science, ICT and Future Planning and National Research Foundation of Korea.
The linac of RISP (Rare Isotope Science Project) includes a charge stripper to obtain better acceleration efficiency. It is located after the lower energy part of the superconducting linac which accelerates 2 charge states, 33 and 34 of uranium beams to about 18 MeV/u. After the charge stripper, 5 charge states around 79 are selected and transported into the higher energy part of the linac through a 180-degree bending section. This work focused on the charge stripper effects on the beam optics in the bending section.

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THPMB029

Simultaneous Two Beam Acceleration Lattice Design Study for the Post Linear Accelerator of RISP

lattice, ion, acceleration, emittance

3294

S.W. Jang
KNU, Deagu, Republic of Korea
E.-S. Kim
Korea University Sejong Campus, Sejong, Republic of Korea

The Rare Isotope Science Project, RISP, is the research complex by using heavy ion accelerator, which RISP research complex consists of front-end system, super conducting linear accelerator(SCL), ISOL system, In-fight system. The original purpose of post linear accelerator was for the alternative acceleration of stable driver beam from ECR ion source and unstable rare isotope beam from ISOL system. The new concept of acceleration method by using post accelerator lattice was studied to get more benefits. The idea was the simultaneous acceleration of stable driver beam and RI beam by using the average A/q value of post accelerator lattice. For the simultaneous two beam acceleration study, we used two ion beams the first one was 58Ni+8 and the other one was 132Sn+20. The beam dynamics simulation was performed by TRACK and TraceWin codes. In this poster, we will describe the results of beam dynamics study for the simultaneous two beam acceleration of the post linear accelerator of RISP.

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THPMB032

Design Study and Multi-particle Tracking Simulation of the IH-DTL with KONUS Beam Dynamics for KHIMA Project

DTL, quadrupole, acceleration, emittance

3299

Y. Lee, E.-S. Kim
Korea University Sejong Campus, Sejong, Republic of Korea
G. Hahn
KIRAMS, Seoul, Republic of Korea
Z. Li
SCU, Chengdu, People's Republic of China

The Korea Heavy Ion Medical Accelerator (KHIMA) project of the Korea Institute of Radiological and Medical Sciences (KIRAMS) has developed heavy ion medical accelerator. The injector system of the accelerator for the KHIMA project is composed of a low energy beam transport line (LEBT), radio frequency quadrupole (RFQ), interdigit H-mode drift tube linac (IH-DTL), and medium energy beam transport line (MEBT). The IH-DTL is designed with KONUS beam dynamics, and KONUS indicates a combined 0˚ structure. Optimization aims are to increase the quality of the beam and to reduce the beam loss. KONUS beam dynamics design and multi-particle tracking simulations of the IH-DTL with LORASR and TraceWIN code are performed.

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THPMB047

Beam Dynamics Studies of the ELENA Electrostatic Transfer Lines in the Presence of Magnetic Stray Fields

experiment, antiproton, solenoid, quadrupole

3351

J. Jentzsch, W. Bartmann, M.A. Fraser, R. Ostojić, G. Tranquille
CERN, Geneva, Switzerland
D. Barna
University of Tokyo, Tokyo, Japan

The ELENA (Extra Low ENergy Antiproton) ring at CERN will further decelerate antiprotons produced at the AD (Antiproton Decelerator) facility from a kinetic energy of 5.3 MeV to 100 keV. The antiprotons will be distributed through a network of electrostatic transfer lines to several experiments, which will replace the existing magnetic transfer lines. The existing experiments and limited space in the AD hall forces the new transfer lines into close proximity to the high-field solenoids used by some experiments to trap the antiprotons. The stray fields from the experimental magnets are known to perturb beam delivery and are a concern for operation at the decreased beam rigidity provided by ELENA. A study was carried out to investigate the influence of stray magnetic fields on the beam, including different ramping periods and operational scenarios. The analytical model of the fields used for simulation will be discussed. Furthermore, trajectory correction algorithms using MADX optic model of the lines have been investigated. The results of these studies as well as specifications of acceptable stray field limits and field attenuation requirements will be presented.

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THPMB048

Design and Optimisation of the ELENA Electron Cooler Gun and Collector

electron, gun, solenoid, cathode

3354

G. Tranquille, J. Cenede
CERN, Geneva, Switzerland

Phase space compression of the antiproton beam in ELENA will be performed by a new electron cooler. The performance of the cooler is greatly influenced by the properties of the electron beam. Careful design of the electron gun electrodes, the quality of the guiding magnetic field and the efficient recuperation of the electrons in the collector ensure that the cooler performance is optimal. We have used COMSOL Multiphysics to design and optimise the complete electron cooler with particular attention to the gun and collector. This software suite uses physics interfaces for modelling common applications and then allows the user to combine the different interfaces in one multi-physics simulation.

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THPMB052

Studies on Electron Beam Injector System for Linac-based Coherent Thz Source in Thailand

electron, undulator, gun, linac

3366

W. Thongpakdi, S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand

Funding: The Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and the Development and Promotion of Science and Technology Talents Project (DPST).
At the Plasma and Beam Physics Research Facility, Chiang Mai University, a thermionic cathode RF electron gun and alpha magnet are used together as an injector system for a linac-based THz source. Investigate the optimal performance of the injector system, beam dynamic simulations are performed by computer codes PARMELA, ASTRA and ELEGANT. The input 3D field distributions of the RF-gun for PARMELA and ASTRA simulations are obtained from the RF modeling program CST Microwave Studio. The beam transport calculation using the program ELEGANT is performed to study behavior of electrons from the gun exit through the alpha magnet, a travelling wave linac, magnet elements, drift tubes, and related beam diagnostic components. Energy slits inside the alpha magnet vacuum chamber is used to select electrons with desired kinetic energies. The alpha magnet compresses electron bunches with certain bunch length before the beam entering the linac to obtain minimum energy spread and shortest bunch length at the experimental station. Results of electron beam optimization with appropriated conditions for generation of intense coherent THz radiation will be reported and discussed in this contribution.
This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and DPST.

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THPMR006

Muon Beam Tracking and Spin-Orbit Correlations for Precision g-2 Measurements

target, proton, dipole, experiment

3397

D. Tarazona, M. Berz, R. Hipple, K. Makino, M.J. Syphers
MSU, East Lansing, Michigan, USA
M.J. Syphers
Fermilab, Batavia, Illinois, USA

The main goal of the Muon g-2 Experiment (g-2) at Fermilab is to measure the muon anomalous magnetic moment to unprecedented precision. This new measurement will allow to test the completeness of the Standard Model (SM) and to validate other theoretical models beyond the SM. The close interplay of the understanding of particle beam dynamics and the preparation of the beam properties with the experimental measurement is tantamount to the reduction of systematic errors in the determination of the muon anomalous magnetic moment. We describe progress in developing detailed calculations and modeling of the muon beam delivery system in order to obtain a better understanding of spin-orbit correlations, nonlinearities, and more realistic aspects that contribute to the systematic errors of the g-2 measurement. Our simulation is meant to provide statistical studies of error effects and quick analyses of running conditions for when g-2 is taking beam, among others. We are using COSY, a differential algebra solver developed at Michigan State University that will also serve as an alternative to compare results obtained by other simulation teams of the g-2 Collaboration.

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THPMR025

Simulation of Beam Behavior Caused by Odd Harmonics of Beam Loading in J-PARC RCS

beam-loading, cavity, acceleration, resonance

3443

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

The J-PARC RCS accelerates 2 bunches at the harmonic number 2. The major Fourier component of the beam current is even harmonics. However, the odd harmonics grow under some conditions even though they are very small amplitude at the beginning. We describe the the particle tracking simulation results for the odd harmonic beam loading effect in the RCS.

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THPMR034

Simulation of Single Particle Dynamics in a Compact Planar Wiggler

wiggler, electron, focusing, synchrotron

3458

D.A. Shkitov, A.E. Harisova, Y.N. Sutygina
TPU, Tomsk, Russia

In this report a description of a simple approach how to simulate a single particle track in a 3D magnetic field using Radia code is presented. Such a simulation maybe useful in order to briefly estimate in a short time the beam dynamics in the magnetic field produced by means of different types of the magnet devices. As an example, a low energy relativistic electron tracking* is performed in a compact 30 cm planar wiggler which produced ~0.4 T magnetic field. The changes of the electron entrance point and motion direction are also available. This simulation is carried out using three-dimensional magnetostatic code - Radia**, where the 4th order Runge-Kutta method was implemented for the trajectory calculations. Since Radia is the Mathematica add-on then a small Wolfram Language code is developed to create the wiggler model, to calculate the electron trajectory and to illustrate the simulation results.
* Knyazik A. et al. Status of UCLA helical permanent-magnet undulator // Proc. of PAC, Canada, WE5RFP076 (2009) 2441
** http://www.esrf.eu/Accelerators/Groups/InsertionDevices/Software/Radia

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THPMR040

Local Optics Corrections in the HL-LHC IR

optics, quadrupole, coupling, controls

3480

J.M. Coello de Portugal, F.S. Carlier, A. Garcia-Tabares, A. Langner, E.H. Maclean, L. Malina, T. Persson, P.K. Skowroński, R. Tomás
CERN, Geneva, Switzerland

For the high luminosity upgrade of the LHC optics correction in the interaction regions is expected to be challenged by the very low β^* and the sizable expected quadrupolar errors in the triplet. This paper addresses the performance and limitations of the segment-by-segment technique to correct quadrupolar and skew quadrupolar errors in the HL-LHC IR via computer simulations. Required improvements to this technique and possible combinations with other correction approaches are also presented including experimental tests in the current LHC IR.

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THPMR044

Short Term Dynamic Aperture with AC Dipoles

dipole, dynamic-aperture, resonance, operation

3496

S. Mönig, J.M. Coello de Portugal, A. Langner, E.H. Maclean, T. Persson, R. Tomás
CERN, Geneva, Switzerland

The dynamic aperture of an accelerator is determined by its non-linear components and errors. Control of the dynamic aperture is important for a good understanding and operation of the accelerator. The AC dipole, installed in the LHC for the diagnostic of linear and non-linear optics, could serve as a tool for the determination of the dynamic aperture. However, since the AC dipole itself modifies the non-linear dynamics, the dynamic aperture with and without AC dipole are expected to differ. This paper will report the results of studies of the effect of the AC dipole on the dynamic aperture.

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THPMR047

Two-beam Tuning in the CLIC BDS

luminosity, collider, sextupole, linear-collider

3508

J. Snuverink, R.M. Bodenstein
JAI, Egham, Surrey, United Kingdom
R. Tomás
CERN, Geneva, Switzerland

Beam tuning in the beam delivery system (BDS) is one of the major challenges for the future linear colliders. In those colliders, due to fast detuning of the final focus optics both beamlines will need to be tuned simultaneously. An initial two-beam tuning study for the Compact Linear Collider (CLIC) BDS had been performed, but was not fully satisfactory. In this paper a more extensive study is presented, as well as several improvements to the tuning algorithm. A comparative study between two competing CLIC final focus systems (FFS), the traditional and the compact FFS, will be discussed.

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THPMW017

Phase Shifter Power Supply Design

controls, electron, power-supply, photon

3576

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

Taiwan Photon Source is an interdisciplinary project. The phase-shift magnet is used to connect the radiation phase between two EPU48s. The power supply for this phase-shift magnet is a key element to determine the phase shift quality. In this report, the theory of the designed circuit is firstly introduced, and then a comparison simulation result and actual measurement is summarized to prove the correctness of theoretical analysis and circuit design.

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THPMW018

Simulation a High Step-up DC-DC Converter for Accelerator

power-supply, operation, sextupole, quadrupole

3579

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

This paper simulation a novel high step-up DC-DC high circuit architecture for storage ring quadrupole and sextupole power supply DC bus voltage. The input source is a low voltage photovoltaic energy through proposed circuit to increase high output voltage system. This volt-age can be as DC bus of quadrupole and sextupole power supply. The part of the circuit has a power switch, isolated transformer inductors, switched capacitors and diodes. This proposed circuit has the advantages of galvanic isolation function, small transformer and high step-up gain and efficiency. Continuous conduction mode (CCM) operation principles are discussed in this paper. Finally, Simplis software has been used for simulation a 24 Vdc step-up to 200 Vdc and 100 w DC-DC converters.
high step-up, switched capacitor, photovoltaic

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THPMW023

Simulation of an Accelerator Pulse Power Supply with an Active Rectifier Using SIMPLORER

power-supply, controls, heavy-ion, ion

3594

F.J. Wu, D.Q. Gao, M. Li
IMP/CAS, Lanzhou, People's Republic of China

In this paper, a simulation model of an accelerator pulse power supply with an active rectifier (voltage-type SVPWM rectifier) was set up based on the C-Model function in SIMPLORER 8.1, which is a simulation software belonging to the ANSOFT corporation. We introduce a SVPWM rectifier into an accelerator pulse power supply to solve its problems such as low input power factor, a large number of AC current harmonics and instable DC bus voltage due to the diode or thyristor rectifier used in it now. Components of control strategies developed in C language were built up and inserted into the simulation project. The simulation results indicate that an accelerator pulse power supply with a SVPWM rectifier can solve the problems above well. For all the control strategies were developed in C language, they can be transplanted into the digital signal processor (DSP) nearly without change for the prototype controlling. So it provides a basis for development of the experimental prototype.

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THPMW029

Feasibility Study of the Fast SPS Ion Injection Kicker System

injection, ion, kicker, flattop

3607

A. Ferrero Colomo, P. Burkel, D. Comte, L. Ducimetière, T. Kramer, V. Senaj, L. Sermeus, F.M. Velotti
CERN, Geneva, Switzerland

As part of the upgrade project for ions the rise time of the injection kicker system into the SPS needs to be improved. The changes being studied include the addition of a fast Pulse Forming Line parallel to the existing Pulse Forming Network for the fast kicker magnets MKP-S. With the PFL an improved magnetic field rise time of 100 ns is targeted. Two different configuration utilizing a 2nd thyratron or two fast diode stacks have been outlined in the past. This paper presents the recent progress on the analogue circuit simulations for both options as well as measurements carried out on a test system. Modelling, optimization and simulation of the entire system with diodes and a second configuration with two thyratron switches are outlined. Measurement results are given and the feasibility of the upgrade is discussed.

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THPMW030

Studies of Impedance-related Improvements of the SPS Injection Kicker System

kicker, impedance, coupling, vacuum

3611

M.J. Barnes, A. Adraktas, M.S. Beck, G. Bregliozzi, H.A. Day, L. Ducimetière, J.A. Ferreira Somoza, B. Goddard, T. Kramer, C. Pasquino, G. Rumolo, B. Salvant, L. Sermeus, J.A. Uythoven, L. Vega Cid, W.J.M. Weterings, C. Zannini
CERN, Geneva, Switzerland
F.M. Velotti
EPFL, Lausanne, Switzerland

The injection kicker system for the SPS consists of sixteen magnets housed in a total of four vacuum tanks. The kicker magnets in one tank have recently limited operation of the SPS with high-intensity beam: this is due to both beam induced heating in the ferrite yoke of the kicker magnets and abnormally high pressure in the vacuum tank. Furthermore, operation with the higher intensity beams needed in the future for HL-LHC is expected to exacerbate these problems. Hence studies of the longitudinal beam coupling impedance of the kicker magnets have been carried out to investigate effective methods to shield the ferrite yoke from the circulating beam. The shielding must not compromise the field quality or high voltage behaviour of the kicker magnets and should not significantly reduce the beam aperture: results of these studies, together with measurements, are presented. In addition results of tests to identify the causes of abnormal outgassing are presented.

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THPMW031

Current and Future Beam Thermal Behaviour of the LHC Injection Kicker Magnet

impedance, kicker, injection, coupling

3615

H.A. Day, M.J. Barnes, L. Ducimetière, L. Vega Cid, W.J.M. Weterings
CERN, Geneva, Switzerland

During Run 1 of the LHC the injection kicker magnets caused occasional operational delays due to beam induced heating with high bunch intensity and short bunch lengths. Significant upgrades were carried out to the injection kicker magnets during long shutdown 1, including a new design of beam screen to reduce the beam induced heating. Nevertheless these kicker magnets may limit the performance of HL-LHC unless additional, mitigating, measures are taken. Hence extensive simulations have been carried out to predict the distribution of the beam induced power deposition within the magnet and detailed thermal analyses carried out to predict the temperature profiles. To benchmark the simulations the predicted temperatures are compared with observables in the LHC. This paper reports on observations of the thermal behaviour of the magnet during run 2 of the LHC, with 25ns beam. In addition the measurement data is used to extrapolate temperature rise for the beam parameters expected for high-luminosity LHC.

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THPMY003

Design of the RISP Vacuum Systems

vacuum, ion, linac, cryomodule

3657

D. Jeon, J.H. Cho, K.B. Lim, H.J. Son, J. Song, S.W. Yoon
IBS, Daejeon, Republic of Korea
H.S. Choi, T. Ha
PAL, Pohang, Republic of Korea
S.R. In
KAERI, Daejon, Republic of Korea
B.C. Kim, K.P. Kim, K.M. Kim, Y.S. Kim
NFRI, Republic of Korea

The vacuum requirement of the RISP heavy ion accel-erator facility has been derived that meets the beam loss requirement and the vacuum system design is carried out using the 3D Molflow+ code verifying the vacuum re-quirement. We used realistic outgassing values of the materials of the vacuum chambers and beam pipes. We are designing detailed vacuum system specification and configuration including pumps, gate valves, and vacuum gauges along with the interlock system and differential pumping stations.

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THPMY007

Vacuum Performance of Amorphous Carbon Coating at Cryogenic Temperature with Presence of Proton Beams

electron, cryogenics, vacuum, experiment

3663

R. Salemme, V. Baglin, G. Bregliozzi, P. Chiggiato
CERN, Geneva, Switzerland

Amorphous carbon (a-C) coating is the baseline electron multipacting mitigation strategy proposed for the Inner Triplets (IT) in the High Luminosity upgrade of the Large Hadron Collider (HL-LHC). As of 2014, the COLD bore EXperiment (COLDEX) is qualifying the performance of a-C coating at cryogenic temperature in a LHC type cryogenic vacuum system. In this paper, the experimental results following a cryogenic vacuum characterization of a-C coating in the 5 to 150 K temperature range are reviewed. We discuss the dynamic pressure rise, gas composition, dissipated heat load and electron activity observed within an accumulated beam time of 9 Ah. The results of dedicated experiments including pre-adsorption of different gas species (H2, CO) on the a-C coating are discussed. Based of phenomenological modeling, up-to-date secondary emission input parameters for a-C coatings are retrieved for electron cloud build-up simulations. Finally, first implications for the HL-LHC ITs design are drawn.

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THPMY008

Mechanical and Vacuum Stability Studies for the LHC Experiments Upgrade

vacuum, ion, experiment, detector

3667

J. Sestak, G. Bregliozzi, P. Chiggiato
CERN, Geneva, Switzerland

In April 2015, the Large Hadron Collider (LHC) has entered its second operational period that will last for 3 years with expected end of the operations at the beginning of 2019. Afterward, the LHC will undergo a long shutdown (LS2) for upgrade and maintenance. The four LHC experiments, ATLAS, ALICE, CMS and LHCb, will experience an important upgrade too. From the design point of view, the LS2 experimental beam vacuum upgrade requires multi-disciplinary approach: based on the geometrical envelope defined by experiment, the vacuum chambers size and shape must be optimized. This included Monte Carlo pressure profile simulations and vacuum stability studies in order to meet the specific pressure requests in the interaction region. Together with vacuum studies the structural analysis are performed in order to optimise chambers thickness and position of the operational and maintenance supports. The material selection for vacuum chambers in the experimental area follows the CERN ALARA (as low as reasonably achievable) principle. This paper gives an overview of the LS2 experimental vacuum sectors upgrades. The most extensive design studies, done for the two experiments CMS and ALICE are discussed in detail.

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THPMY028

Technical Overview of the PAL-XFEL Conventional Facility

undulator, site, linac, survey

3715

I. Mok, M.S. Hwang, T.-H. Kang, K.W. Kim, K.R. Kim, S.H. Kim, S.N. Kim, Y. C. Kim, B.H. Lee, H.M. Lee, M.S. Lee, B.I. Moon, K.W. Seo, C.H. Son, C.W. Sung, J. Yang
PAL, Pohang, Republic of Korea
Y.C. Kim, J.H. Lee
Haenglim Architecture & Engineering Co. Ltd, Seoul, Republic of Korea
I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.W. Yong
Posco Engineering & Construction., Ltd., Gyeongsangbuk-do, Republic of Korea

Pohang Accelerator Laboratory (PAL) has finished construction of a 1,110m long 10GeV X-ray free electron laser (XFEL) linear accelerator building in FY2015. In order to secure high-sensitive of XFEL accelerating devices, more advanced and well proven technologies were adopted in the design of the building. These are the ground improvement underneath the tunnel and tunnel structure itself against the possible ground deformation, air conditioning system to maintain the temperature and humidity in the tolerable ranges and architectural zoning. In this paper we describe the features of design and construction of the XFEL accelerator building.

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THPMY029

Technical Overview of the PAL-XFEL Low-Conductivity Water Cooling System

controls, operation, laser, ion

3718

B.H. Lee, H.-G. Kim, K.W. Kim, K.R. Kim, S.H. Kim, Y. C. Kim, H.M. Lee, M.S. Lee, H. Matsumoto, I. Mok, C.W. Sung, J. Yang
PAL, Pohang, Kyungbuk, Republic of Korea
J.H. Jeon
Taeyoung, Seoul, Republic of Korea
K.T. Kim
HMT, Pohang, Republic of Korea
I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea

Pohang Accelerator Laboratory (PAL) started operation of an X-ray Free Electron Laser (XFEL) based on 10GeV linear accelerator in FY2015. For accurate temperature control of the various XFEL accelerator devices, a low-conductivity water (LCW) cooling system were installed. The LCW pump station generates LCW controlling the temperature variation within ±0.1°C. The LCW is supplied to klystrons including modulators and various control devices. On the other hand, the precision temperature controlled water to minimize temperature variation down to ±0.02°C. This water is supplied to accelerating columns, wave guide and SLED. Therefore, this paper shows the design, construction and operation of the LCW cooling system.

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THPOR028

Numerical Analysis of Stresses for the Target of the ILC 300 Hz Conventional Positron Source

target, positron, linear-collider, collider

3838

S. Jin, J. Gao
IHEP, Beijing, People's Republic of China
T. Omori
KEK, Ibaraki, Japan
P. Sievers
CERN, Geneva, Switzerland

A 300Hz conventional, e^- driven positron source for the ILC is proposed by an international team. In this paper, we focus on numerical analysis of dynamic stresses in the Tungsten target. These are driven by the pulsed e-beam, which causes rapid heating and subsequent, dynamic loads in the target which can lead to fracture and failure of it. A program of ANSYS workbench is used in the study. The dynamic stresses from both of extremely short (10 ns) and nominal (1μs) thermal pulses are systematically studied in various target related parts such as small spheres, cylinders. Particular attention has also been paid to the buckling of foils.
(*) The first proposal was published in NIMA 672 (2012) 52-56 by
T. Omori, et. al.. The authors come from seven institutes including KEK, Hiroshima U., DESY, ANL, IHEP, SOKENDAI, U. of Hamburg

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THPOR030

Commissioning and First Performance Studies of a Single Vertical Beam Halo Collimation System at ATF2

background, photon, collimation, wakefield

3844

N. Fuster-Martínez, A. Faus-Golfe
IFIC, Valencia, Spain
P. Bambade, A. Faus-Golfe, S. Wallon, R.J. Yang
LAL, Orsay, France
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
I. Podadera, F. Toral
CIEMAT, Madrid, Spain
T. Tauchi, N. Terunuma
Sokendai, Ibaraki, Japan

A single vertical beam halo collimation system has been installed in the ATF2 beamline to reduce the background that could limit the precision of the diagnostics located in the post-IP beamline. On this paper the commissioning and first performance studies of a single vertical beam halo collimation system are reported. Furthermore realistic efficiency studies have been done using the simulation code BDSIM and compared with the first experimental tests.

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THPOR032

Effect and Optimisation of Non-Linear Chromatic Aberrations of the CLIC Drive Beam Recombination at CTF3

optics, emittance, sextupole, operation

3852

D. Gamba, R. Corsini, P.K. Skowroński, F. Tecker
CERN, Geneva, Switzerland
P. Burrows
JAI, Oxford, United Kingdom
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

The CLIC design relies on the two-beam acceleration principle, i.e. the energy transfer from the so called drive beam to the main colliding beams. At the CLIC Test Facility (CTF3) at CERN the feasibility of this principle is being tested in terms of performance and achievable specifications. The high-current drive beam is generated by recombining its parts in a delay loop and a combiner ring. Preserving the drive beam emittance during the recombination process is crucial to ensure beam-current and power production stability. Present theoretical and experimental studies show that non-linear energy dependence of the transverse optics heavily spoils the quality of the recombined beam. Conventionally these effects are cured by means of non-linear corrections using sextupoles. In this work we propose a mitigation of these effects by optimising the linear lattice, leading to a more robust and easy to operate drive beam recombination complex. The latest results are presented.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR032

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THPOR040

Emittance Growth by Misalignments and Jitters in SuperKEKB Injector Linac

emittance, linac, acceleration, quadrupole

3871

Y. Seimiya, Y. Enomoto, K. Furukawa, T. Higo, T. Kamitani, F. Miyahara, Y. Ohnishi, M. Satoh, T. Suwada, M. Tanaka
KEK, Ibaraki, Japan

Funding: This work was partly supported by JSPS KAKENHI Grant Number 16K17545.
SuperKEKB injector linac have to transport high-charged beam with low emittance to SuperKEKB ring for high luminosity, 8¥times10³⁵. For the low emittance, photocathode RF gun was adopted as electron source. One of the main reason of the beam emittance blow-up electron linac is generally induced by wakefield in acceleration cavities. A charged beam with a offset from a center of a cavity is affected by the wakefield depending on the offset size in the acceleration cavity and the beam emittance is increased. This emittance blow-up can be eliminated by appropriate steering magnet control so as to cancel the wake effect in the acceleration cavity. We perform particle tracking simulation with some misalignments and beam jitter. Emittance growth by the misalignments and the beam jitter is evaluated in this report.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR040

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THPOR046

CEPC 650 MHz Klystron Development

klystron, gun, electron, operation

3891

Z.S. Zhou, D. Dong, S. Fukuda, Z.J. Lu, G. Pei, S.C. Wang, O. Xiao, .. Zaib-un-Nisa
IHEP, Beijing, People's Republic of China
S. Fukuda
KEK, Ibaraki, Japan

The CEPC collider beam power is about 100 MW, so the efficiency of amplifier is very important for cost of project implementation. The high power klystron is the more attractive because of its potential for higher eﬃciency than solid state amplifier. For CEPC klystron output power is not so high, the operation voltage can be a safe value. Advantage for single beam: reliable, low phase noise, some perspective technology can be used to improve efficiency. The accelerating frequency is 650 MHz, output power is a maximum power of 800kW, and efficiency is about 70%. In this paper, the specifications and developments of 650 MHz CW klystron, including the klystron gun prototype and future high efficiency consideration are summarized.

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THPOR052

A Beam-based Measurement of the LHC Beam Dump Kicker Waveform

extraction, kicker, operation, dumping

3911

M.A. Fraser, W. Bartmann, C. Bracco, E. Carlier, B. Goddard, V. Kain, N. Magnin, J.A. Uythoven, F.M. Velotti
CERN, Geneva, Switzerland

The increase of the LHC collision energy to 13 TeV after Long Shutdown 1 has doubled the operational energy range of the LHC beam dump system (LBDS) during Run 2. In preparation for the safe operation of the LHC, the waveform of the LBDS extraction kicker was measured using beam-based measurements for the first time during the machine's re-commissioning period. The measurements provide a reference for a more precise synchronisation of the dump system and abort-gap timing, and provide an independent check of the system's calibration. The precision of the beam-based technique allowed the necessary adjustments to the LBDS trigger delays to ensure the synchronous firing of the LBDS at all beam energies up to 6.5 TeV. In this paper the measurement and simulation campaign is described and the performance of the system reported.

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THPOR055

Characterisation of the SPS Slow-extraction Parameters

extraction, proton, controls, target

3918

F.M. Velotti, W. Bartmann, T. Bohl, C. Bracco, K. Cornelis, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel
CERN, Geneva, Switzerland

The Super Proton Synchrotron (SPS) is the last accelerator in the Large Hadron Collider (LHC) injector chain but its main users are the fixed-target experiments located in the North Area (NA). The beams, which are among the most intense circulating in the SPS, are extracted to the NA over several thousands of turns by exploiting a third-integer resonant extraction. The unavoidable losses intrinsic to such an extraction makes its optimisation one of the main priorities for operation, to reduce beam induced activation of the machine. The settings of the extraction systems, together with the tune sweep speed and the beam characteristics (momentum spread, emittance, etc.) are the parameters that can be controlled for spill and loss optimisation. In this paper, the contribution of these parameters to the slow-extraction spill quality are investigated through tracking simulations. The simulation model is compared with beam measurements and optimisations suggested.

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THPOW002

Electromagnetic, Thermal, and Structural Analysis of a THOMX RF Gun Using ANSYS

gun, cavity, electron, coupling

3925

M. El Khaldi, J. Bonis, A. Camara, L. Garolfi, A. Gonnin
LAL, Orsay, France

Photocathode RF guns are used in the first stage of electron beam generation and acceleration. The RF gun of THOMX is a 2.5 cell standing wave copper cavity with resonance frequency of 2998.55 MHz at 30 °C under vacuum. The metal photocathode such as copper or magnesium is inserted into the backplane of the cavity. Due to high repetition rates up to 50 Hz with the average dissipated power into the internal surfaces up to 1.5 kW, causing a heating and deformation of the cavity shape. Therefore, the cooling system of the device has to be well designed to take under control the deformations of the structure, providing a temperature increase as small and uniform as possible. For this purpose a fully coupled electromagnetic-thermal-structural finite element analysis on this gun has been performed with Ansys workbench. Numerical results show that the gun could operate at 3 μs RF pulse length and 50 Hz repetition rate with an average dissipated power of 1.5 kW. The gun average temperature is around 30 °C while the incoming water temperature is around 24°C. Internal speed of water is 2.5 m/s which corresponds to 15 l/min for the incoming water. The total pressure drop is around 0.4 bar

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THPOW017

VELA Photoinjector Cavity RF Investigations

cathode, cavity, operation, electron

3968

L.S. Cowie, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
J.A. Mitchell
Lancaster University, Lancaster, United Kingdom
M.D. Roper
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

One of two ALPHA-X photocathode gun cavities, designed and fabricated at the Laboratoire de l'Accélérateur Linéaire, has been in operation on the VELA electron accelerator at Daresbury Laboratory since first beam in April 2013. In this time the maximum beam momentum recorded is 5.06 MeV/c. An investigation of the cavity has been performed with the aim of reconciling the expected momentum of over 6 MeV/c with the measured momentum. RF and beam simulation results are presented along with low power RF measurements of the cavity. One source of momentum loss, the flatness of the cathode face, is identified and rectified.

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THPOW018

Simulations of Field Emitted Dark Current Dynamics in DC Photoinjectors

gun, electron, cavity, space-charge

3971

P.J. Tipping, J.W. McKenzie, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Field emission is a concern in injectors with DC photoelectron guns because of the constant generation of dark current, which is accelerated down the beam line and can deteriorate the photoemitted bunch quality and lead to hardware damage. Simulations were carried out on the co-propagation of a field emitted, dark current halo and a photoemitted bunch in a typical 350 kV gun as used in an ERL or FEL injector, followed by a single cell buncher cavity. The photoemitted bunch repelled the halo longitudinally, leaving the area in the centre of the bunch with very low dark current, surrounded by two peaks of relatively high current at the front and back of the bunch. The peaks in current occur at all levels of dark current and were about 3.5 times the amplitude of the undisturbed dark current. The buncher caused the dark current to overcompress, forming a 'ghost' pulse an order of magnitude larger than the initial level of dark current, in front of the photoemitted bunch.

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THPOW028

Automated Design for Standing Wave Electron Photoguns: TOPGUN RF Design

gun, toolkit, coupling, cavity

3999

A.D. Cahill
UCLA, Los Angeles, California, USA
M. Dal Forno, V.A. Dolgashev
SLAC, Menlo Park, California, USA

Funding: DOE SCGSR and DOE/SU Contract DE-AC02-76-SF00515
Systematic design of RF photoguns involves multiple RF simulations in conjunction with beam dynamic simulations. RF simulations include tuning gun frequency, matching the gun to the feeding RF circuit, balancing the on axis electric fields between gun cells, minimizing surface electric and magnetic fields and power consumption, and optimizing separation of resonant mode frequencies. We created a tool that allows this multiple parameter optimization to be done automatically. We used SUPERFISH to accomplish the RF simulations. We present an example of the rf photogun TOPGUN design using these tools.

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THPOW041

Field Error Correction Considerations of Cryogenic Permanent Magnet Undulator (CPMU) for High Energy Photon Source Test Facility (HEPS-TF)*

cryogenics, undulator, operation, electron

4038

Y.F. Yang, H.H. Lu, S.C. Sun, X.Z. Zhang
IHEP, Beijing, People's Republic of China

Considerations are made for field error corrections of a 2m-long CPMU in built for HEPS-TF. Field changes in cooling to liquid nitrogen temperature are simulated. 1st field integral of terminal changes by tens of Gauss cm and RMS of phase errors induced by cold contraction is less than 1° when temperature gradient along girder is below 1.5K/m. Field signature of magic finger is unchanged with temperature. Strategy of the field error correction is discussed.

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THPOW042

Start-to-End Simulation on Terahertz Superradiation of Ultrashort Electron Bunch in an Undulator

radiation, undulator, electron, laser

4041

X.L. Su, Y.-C. Du, W.-H. Huang, C.-X. Tang, D. Wang, L.X. Yan, Z. Zhang
TUB, Beijing, People's Republic of China

The narrowband, intense and frequency-tunable THz radiation can be generated by letting an ultrashort electron bunch pass through an undulator. Start-to-end simulation of terahertz radiation from electron bunch in an undulator is studied in this paper. GPT code is used to track particle distribution from the photocathode RF gun to the entrance of the undulator and Genesis 1.3 is applied to simulate the radiation. The simulation results agree well with theoretical predictions.

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THPOW050

Upgrade of Septum Magnets of the Transfer Line in TPS

septum, injection, power-supply, booster

4057

C.S. Yang, C.-H. Chang, Y.L. Chu, J.C. Huang, C.-S. Hwang, J.C. Jan, F.-Y. Lin
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) is a 3-GeV light source. The full current of the storage beam and commissioning of insertion devices are still in progress. An improved injection between the booster ring (BR) and the storage ring (SR) was implemented to increase the efficiency of injection and the reliability of the electrical parts. A DC septum (length 0.8 m) was replaced with an AC septum (length 1 m, type C) to decrease the leakage field and to relax the loading of the power supply. Mapping the field with mu-metal shielding was also implemented to diminish the leakage field from the AC septum. The lattice of the transfer line between the booster ring and the storage ring, BTS, was also rearranged to meet the new injection requirements. The performance of the AC septum with mu-metal shielding and the upgrade of the BTS lattice are discussed in this paper.

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THPOY002

The New External Beamline for Detector Tests at ELSA

quadrupole, radiation, electron, detector

4088

N. Heurich, F. Frommberger, P. Hänisch, W. Hillert
ELSA, Bonn, Germany

At the electron accelerator ELSA, a new external beam line has been constructed whose task is to provide a primary electron beam for detector tests. Using a slow resonance extraction method, it is possible to extract a quasi continuous electron beam with a maximum energy of 3.2 GeV to the test area. An external beam current of 100 pA to 1 fA can be realized. A further reduction of the beam current is envisaged as well. The beam width can be changed in both transverse directions from 1 mm to 8 mm. To dump and simultaneously measure the current of the electron beam behind the detector components a Faraday cup consisting of depleted uanium is used. The residual radiation leaving the cup is absorbed in a concrete casing. The radiation protection concept for the entire area of the new beamline was designed with the help of the Monte Carlo simulation program Fluka. In addition to the concrete casing, radiation protection walls were built to allow a safe working environment in the neighboring control room.

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THPOY021

NSLS-II Dedicated Python Tools for Simulation and Analysis

lattice, closed-orbit, quadrupole, controls

4134

J. Choi
BNL, Upton, Long Island, New York, USA

Funding: DOE contract No: DE-SC0012704
Python is a high-level interpreted programming language. Despite its slow benchmarks, because of its fast coding cycle and dynamic property, the users are increasing fast in all areas. Also, because it does not need special care for the memory management, both professional and non-professional programmers can easily make bug-free code just by concentrating on logics. Furthermore, fast increasing libraries are making the language more and more useful. With these advantages, we developed python tools which simulate and analyze the particle accelerator with some parts being dedicated to NSLS-II operation.

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THPOY032

The Dual Use of Beam Loss Monitors at FAIR-SIS100: General Diagnostics and Quench Prevention of Superconducting Magnets

ion, quadrupole, beam-losses, extraction

4167

S. Damjanovic, P. Kowina, C. Omet, M. Sapinski, M. Schwickert, P.J. Spiller
GSI, Darmstadt, Germany

In view of the planned coverage of the FAIR-SIS100 synchrotron with beam loss monitors (BLMs), FLUKA studies were performed aiming at two goals: i) evaluation of the sensitivity of the LHC-IC type detectors to the potential beam losses at SIS100; ii) estimation of the BLM quench prevention threshold via the correlation between the energy deposition inside the superconducting coils and the BLM active volume. A full spectrum of ion species and energies to be accelerated with SIS100 were considered in the simulations, showing a great sensitivity to the beam losses. An interesting finding of this study was that, for the same beam loss location, the quench prevention thresholds were almost identical for all ion species/energies including protons.

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THPOY034

Simulations of the Beam Loss Distribution at J-PARC Main Ring

proton, scattering, radiation, operation

4175

B. Yee-Rendón, H. Kuboki, Y. Sato, K. Satou, M.J. Shirakata, T. Toyama
KEK, Ibaraki, Japan
H. Harada
JAEA/J-PARC, Tokai-mura, Japan

The Japan Proton Accelerator Research Complex (J-PARC) is integrated by a set of high intensity proton accelerators. At this operation level, the monitoring and control of the beam losses and residual radiation are priority for its safe performance and maintenance. At Main Ring (MR), a discrepancy appears between the beam loss signal detected by the monitors and the residual dose measured. To understand this difference and the mechanism that produces these losses, a beam simulation study is implemented using the Strategic Accelerator Design (SAD) and Geometry and Tracking (Geant4) code. The first stage of the survey uses SAD to obtain the location of the losses around the lattice per turn. Then, Geant4 produces the secondary showers in the elements. Finally, we make the extrapolation with the residual radiation and compare with the measurements. The description and results of this work are presented in this paper.

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THPOY043

Time Scale of Crab Cavity Failures Relevant for High Luminosity LHC

cavity, damping, resonance, luminosity

4196

K.N. Sjobak, R. Bruce, H. Burkhardt, A. Macpherson, A. Santamaría García
CERN, Geneva, Switzerland
R. Kwee-Hinzmann
Royal Holloway, University of London, Surrey, United Kingdom
A. Santamaría García
EPFL, Lausanne, Switzerland

Funding: Research supported by the High Luminosity LHC project
A good knowledge of the effects of the crab cavities, required for the baseline High Luminosity LHC (HL-LHC), is needed before the results of the first tests of crab cavity prototypes in the SPS, planned for 2018, will be available. In case of crab cavity failures, we have to make sure that time scales are long enough so that the beams can be cleanly dumped before damage by beam loss occurs. We discuss our present knowledge and modeling of crab cavity induced beam losses, combined with mechanical deformation. We discuss lower limits on the time scales required for safe operation, and possible failure mitigation methods.

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FRXBA01

Beam Halo Characterization and Mitigation

emittance, linac, operation, collimation

4248

A.V. Aleksandrov
ORNL, Oak Ridge, Tennessee, USA

Beam halo is a serious issue in many machines, such as high intensity linacs and synchrotrons. This presentation reviews recent advances in halo characterization techniques, as well as methods to mitigate beam halo, such as collimation with associated handling of created secondary particles.

Slides FRXBA01 [17.743 MB]

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