IPAC2021 - List of Keywords (coupling)

Paper	Title	Other Keywords	Page
MOPAB007	Prospect for Interaction Region Local Coupling Correction in the LHC Run 3	optics, quadrupole, luminosity, MMI	61
	F. Soubelet, T.H.B. Persson, R. Tomás García CERN, Geneva, Switzerland O. Apsimon, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom O. Apsimon, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work was supported by STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) and CERN. Successful operation of large scale particle accelerators depends on the precise correction of unavoidable magnet field or alignment errors present in the machine. In the LHC Run 2, local linear coupling in the Interaction Regions (IR) has been proven to have a severe impact on beam size and hence the luminosity - up to a 50% decrease -, making its handling a target for Run 3 and High Luminosity LHC (HL-LHC). However, current measurement methods are not optimised for local IR coupling. In this contribution, an approach to accurately minimise IR local coupling based on correlated external variables such as the \|C-\| is proposed. The validity of the method is demonstrated through simulations and benchmarked against theoretical values, such as Resonance Driving Terms (RDTs) and Ripken parameters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB007
About •	paper received ※ 17 May 2021 paper accepted ※ 23 July 2021 issue date ※ 19 August 2021
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MOPAB019	Possible Application of Round-to-Flat Hadron Beam Creation Using 3rd Order Coupling Resonances for the Electron-Ion Collider	resonance, emittance, sextupole, electron	99
	J. Kallestrup PSI, Villigen PSI, Switzerland X. Gu BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. An Electron-Ion Collider (EIC) is planned to be built in Brookhaven National Laboratory with the contribution from Jefferson National Laboratory. To have a high luminosity, both the EIC ion bunch and the EIC electron bunch are designed to be flat during their collision. The existing injector source provides a round beam of width 2.5 um rad transverse emittances. In this paper we investigate the option of dynamically crossing the 2Qx-Qy coupling resonance in order to create a flat-beam with emittance ratio Ex/Ey of up to 4. Furthermore, we explore the possibility of using a pulsed- or AC skew sextupole magnets to achieve a similar effect. Using one of these methods for flat beam creation will help lower the ion beam cooling time.
	Poster MOPAB019 [0.323 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB019
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021
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MOPAB020	Improvements to the SLS Booster Synchrotron Performance Towards SLS 2.0	booster, emittance, sextupole, injection	103
	J. Kallestrup, M. Aiba PSI, Villigen PSI, Switzerland
	The Swiss Light Source (SLS) storage ring will undergo a major upgrade to a multi-bend achromat lattice. The existing injector complex will be reused with few modifications. However, the SLS booster synchrotron has not been studied since the initial commissioning in years 2000-2001. We plan to apply an emittance exchange in the booster to lower the horizontal emittance, which is a critial parameter for the injection. Here, we present improvements to the SLS booster as a preparation for SLS 2.0 upgrade project. The vertical beam size is decreased by 50\% by the use of vertical orbit correctors without beam position monitors, leading also to suppression of vertical dispersion and a factor 10 reduction of the transverse coupling coefficient. The emittance exchange reflected these improvements in the horizontal emittance, achieving a factor of 9-10 reduction. Lastly, a fast head-tail instability limiting the injection rate into the storage ring is discovered and subsequently suppressed by correcting the chromaticities.
	Poster MOPAB020 [0.380 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB020
About •	paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 30 August 2021
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MOPAB024	Efficient Coupling of Hydrodynamic and Energy-Deposition Codes for Hydrodynamic-Tunnelling Studies on High-Energy Particle Accelerators	simulation, target, proton, experiment	119
	C. Wiesner, F. Carra, J. Kruse-Hansen, M. Masci, D. Wollmann CERN, Meyrin, Switzerland Y. Nie KIT, Karlsruhe, Germany
	The machine-protection evaluation of high-energy accelerators comprises the study of beyond-design failures, including the direct beam impact onto machine elements. In case of a direct impact, the nominal beam of the Large Hadron Collider (LHC) would penetrate more than 30 meters into a solid copper target. The penetration depth due to the time structure of the particle beam is, thus, significantly longer than predicted from purely static energy-deposition simulations with 7 TeV protons. This effect, known as hydrodynamic tunnelling, is caused by the beam-induced density depletion of the material at the target axis, which allows subsequent bunches to penetrate deeper into the target. Its proper simulation requires, therefore, to sequentially couple an energy-deposition code and a hydrodynamic code for the different target densities. This paper describes a method to efficiently couple the simulations codes Autodyn and FLUKA based on automatic density assignment and input file generation, and presents the results achieved for a sample case.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB024
About •	paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 28 August 2021
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MOPAB087	Design of a Multi-Bunch Feedback Kicker in SPEAR3	kicker, impedance, simulation, feedback	327
	K. Tian, J.B. Langton, NL. Parry, J.A. Safranek, J.J. Sebek SLAC, Menlo Park, California, USA
	The new Multi-bunch feedback kickers have been designed to replace the current device loaned from ALS. In this paper, we first present the specification of the kickers based on the beam physics requirements. Then the mechanical design of the kicker is elaborated. Numerical simulations, both in time domain and in frequency domain, are conducted for evaluating the shunt impedance and beam coupling impedance of the kicker. Surface heating induced from the beam or the external source is estimated from the numerical results as well.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB087
About •	paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 01 September 2021
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MOPAB103	Study of Transverse Oscillation Coupling and Possibility of Its Minimization in SKIF (Novosibirsk)	quadrupole, emittance, sextupole, storage-ring	383
	D. Leshenok BINP, Novosibirsk, Russia G.N. Baranov, E.B. Levichev, S.A. Nikitin BINP SB RAS, Novosibirsk, Russia
	The vertical emittance and, in general, the vertical beam size and angular divergence are of paramount importance in the SKIF (Russian acronym for Siberian Circular Photon Source) project developed in Novosibirsk. Therefore, a detailed simulation of the corresponding influence of possible errors in the storage ring was carried out with cross-validation by different methods. Variants of cross-coupling correction are proposed and modeled to obtain a vertical emittance of the order of one picometer simultaneously with minimizing vertical dispersion.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB103
About •	paper received ※ 18 May 2021 paper accepted ※ 17 August 2021 issue date ※ 19 August 2021
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MOPAB142	A Compact, Low-Field, Broadband Matching Section for Externally-Powered X-Band Dielectric-Loaded Accelerating Structures	vacuum, GUI, simulation, linac	495
	Y. Wei, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom H. Bursali Sapienza University of Rome, Rome, Italy N. Catalán Lasheras, S. Gonzalez Anton, A. Grudiev, R. Wegner, Y. Wei CERN, Meyrin, Switzerland B.T. Freemire, C.-J. Jing Euclid TechLabs, Solon, Ohio, USA J. Sauza-Bedolla Lancaster University, Lancaster, United Kingdom Y. Wei, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	It has been technically challenging to efficiently couple external radiofrequency (RF) power to cylindrical dielectric-loaded accelerating (DLA) structures. This is especially true when the DLA structure has a high dielectric constant. This contribution presents a novel design of a matching section for coupling the RF power from a circular waveguide to an X-band DLA structure with a dielectric constant ε_r=16.66 and a loss tangent \tanθ = 3.43× 10^-5. It consists of a very compact dielectric disk with a width of 2.035 mm and a tilt angle of 60 degrees, resulting in a broadband coupling at a low RF field which has the potential to survive in the high-power environment. To prevent a sharp dielectric corner break, a 45-degree chamfer is added. Moreover, a microscale vacuum gap, caused by metallic clamping between the thin coating and the outer thick copper jacket, is studied in detail. Based on simulation studies, a prototype of the DLA structure with the matching sections was fabricated. Results from preliminary bench measurements and their comparison with design values will also be discussed.
	Poster MOPAB142 [2.617 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB142
About •	paper received ※ 11 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021
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MOPAB155	Magnetic Breakdowns in Side-Coupled X-Band Accelerating Structures	impedance, simulation, cavity, accelerating-gradient	540
	S.P. Antipov, P.V. Avrakhov, S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA V.A. Dolgashev SLAC, Menlo Park, California, USA C. Jing Euclid Beamlabs, Bolingbrook, USA
	Funding: DOE SBIR Side coupled accelerating structures are popular in the industrial realizations of linacs due to their high shunt impedance and ease of tuning. We designed and fabricated a side-coupled X-band accelerating structure that achieved 133 MOhm/m shut impedance. This structure was fabricated out of two halves using a novel brazeless approach. The two copper halves are joined together using a stainless steel joining piece with knife edges that bite into copper. This structure had been tested at high power at SLAC National Accelerator Laboratory. The performance of the structure had been limited by magnetic breakdowns on the side-coupling cells. In this paper we will present results of the high gradient tests and after-test analysis. Scanning electron microscopy images show a typical magnetic-field induced breakdown.
	Poster MOPAB155 [1.069 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB155
About •	paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 01 September 2021
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MOPAB162	The First Trial of XY-Coupled Beam Phase Space Matching for Three-Dimensional Spiral Injection	injection, site, experiment, solenoid	553
	M.A. Rehman, K. Furukawa, H. Hisamatsu, T. Mibe, H. Nakayama, S. Ohsawa, N. Saito, K. Sasaki KEK, Ibaraki, Japan H. Hirayama, H. Iinuma, K. Oda Ibaraki University, Ibaraki, Japan R. Matsushita The University of Tokyo, Graduate School of Science, Tokyo, Japan N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Funding: Work supported by "Grant in Aid" for Scientific Research, JSPS (KAKENHI# 26287055, KAKENHI#19H00673) The most recent measurement of muon g-2 results in a 3.8σ discrepancy with the equally precise theoretical prediction. The J-PARC muon g-2/EDM experiment (E34) is in preparation to decipher this discrepancy and unravel the new physics beyond the standard model. The precision goal for g-2 is 0.1 ppm. To achieve this precision goal a novel 3-D spiral injection scheme has been devised to inject and store the beam into a small diameter MRI-type storage magnet for E34. The new injection scheme features smooth injection with high storage efficiency for the compact magnet. However, the spiral injection scheme is an unproven idea, therefore, a Spiral Injection Test Experiment (SITE) at KEK Tsukuba Campus is underway to establish this injection scheme. Due to the axial symmetric field of the solenoid magnet, a strongly XY-coupled beam is required. To produce the required phase space for the solenoid-type storage magnet, a beam transport line consisting of three rotatable quadrupole magnets has been designed and built for SITE. The vertical beam size reduction by means of phase space matching and other geometrical information has been successfully measured by the wire scanners.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB162
About •	paper received ※ 20 May 2021 paper accepted ※ 28 May 2021 issue date ※ 01 September 2021
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MOPAB180	AGS Dynamic Aperture at Injection of Polarized Protons and Helions	dynamic-aperture, proton, injection, extraction	610
	K. Hock, H. Huang, F. Méot, N. Tsoupas BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. Polarized helions are part of the physics program for the future EIC. An AC dipole has been installed in the AGS Booster to preserve polarization as helions are accelerated to \|Ggamma\|=10.5. Extraction from the AGS Booster at \|Ggamma\|=7.5 is possible but: would involve crossing an intrinsic resonance in the AGS, and would be the lowest rigidity beam injected into the AGS, and therefore experiences strong distortions of the optical functions because of the AGS two partial snakes. This lower rigidity would exacerbate the optical distortions from the snake, reducing the dynamic aperture. A comparison of the dynamic aperture of protons at Ggamma=4.5 to that of helions at \|Ggamma\|=7.5 and \|Ggamma\|=10.5 show that extraction at \|Ggamma\|=10.5 provides a larger dynamic aperture. This larger aperture would allow helions to be placed inside the spin tune gap generated by the two partial helices in AGS earlier in the cycle.
	Poster MOPAB180 [0.453 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB180
About •	paper received ※ 17 May 2021 paper accepted ※ 31 May 2021 issue date ※ 20 August 2021
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MOPAB184	Unsupervised Learning Techniques for Tune Cleaning Measurement	ISOL, optics, luminosity, quadrupole	624
	H. Garcia Morales Oxford University, Physics Department, Oxford, Oxon, United Kingdom E. Fol, R. Tomás García CERN, Meyrin, Switzerland
	Precise measurements of tune and its stability are crucial for various optics analyses in the LHC, e.g. for the determination of the beta star using K-modulation. LHC BBQ system provides tune measurements online and stores the tune data. We apply unsupervised machine learning techniques on BBQ tune data in order to provide an automatic outlier detection method for better measurements of tune shifts and unexpected tune jitters.
	Poster MOPAB184 [0.354 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB184
About •	paper received ※ 14 May 2021 paper accepted ※ 09 June 2021 issue date ※ 11 August 2021
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MOPAB187	Design and Calculation of the RF System of DC140 Cyclotron	cyclotron, cavity, simulation, resonance	636
	A.S. Zabanov, V.B. Zarubin JINR/FLNR, Moscow region, Russia J. Franko, G.G. Gulbekyan, I.V. Kalagin, N.Yu. Kazarinov, S.V. Mitrofanov, V.A. Sokolov, K. Verlamov JINR, Dubna, Moscow Region, Russia
	Flerov Laboratory of Nuclear Reaction of Joint Institute for Nuclear Research carries out the works under creating of FLNR JINR Irradiation Facility based on the cyclotron DC140. The facility is intended for SEE testing of microchip, for production of track membranes and for solving of applied physics problems. The main systems of DC140 are based on the DC72 cyclotron ones that now are under reconstruction. The DC140 cyclotron is intended for acceleration of heavy ions with mass-to-charge ratio A/Z within interval from 5 to 5.5 up to two fixed energies 2.124 and 4.8 MeV per unit mass. The intensity of the accelerated ions will be about 1 pmcA for light ions (A<86) and about 0.1 pmcA for heavier ions (A>132). The designed RF-system of the DC-72 cyclotron with a half-wave cavity is not suitable due to the big vertical size. For this reason, a new quarter-wave RF-system was developed for the DC140 cyclotron project. The results of calculating the parameters of the new RF-system are given in this work.
	Poster MOPAB187 [0.488 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB187
About •	paper received ※ 17 May 2021 paper accepted ※ 24 May 2021 issue date ※ 15 August 2021
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MOPAB195	Development of a Disk-and-Washer Cavity for the J-PARC Muon g-2/EDM Experiment	cavity, experiment, linac, quadrupole	658
	Y. Takeuchi, J. Tojo Kyushu University, Fukuoka, Japan E. Cicek, K. Futatsukawa, N. Kawamura, T. Mibe, M. Otani, T. Yamazaki, M. Yoshida KEK, Ibaraki, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan R. Kitamura, Y. Kondo, T. Morishita JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Nakazawa Ibaraki University, Hitachi, Ibaraki, Japan N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Sue, K. Sumi, M. Yotsuzuka Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan H.Y. Yasuda University of Tokyo, Tokyo, Japan
	At J-PARC, an experiment using muons accelerated by a linac is planned to measure the anomalous magnetic moment of muons and to search for the electric dipole moment. A 1296 MHz disk and washer (DAW) coupled cavity linac (CCL) is being developed for use in the middle beta section of the muon linac. The DAW CCL consists of 14 tanks with 11 cells each. All tanks are connected by bridge couplers and electromagnetic quadrupole doublets for focusing are installed in each bridge coupler. The basic design of the DAW cavity has already been completed, and now detailed cavity design studies and manufacturing process studies are underway. In this poster, we will report about these studies and the preparation status of manufacturing the DAW cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB195
About •	paper received ※ 20 May 2021 paper accepted ※ 01 June 2021 issue date ※ 23 August 2021
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MOPAB211	Beam Coupling Impedances of Ferrite-Loaded Cavities: Calculations and Measurements	cavity, impedance, dipole, resonance	696
	S.S. Kurennoy, R.C. McCrady LANL, Los Alamos, New Mexico, USA
	We have developed an efficient method of calculating impedances in cavities with dispersive ferrite dampers. The ferrite dispersive properties in the frequency range of interest are fitted in CST, which allows using both wakefield and lossy eigenmode solvers. A simple test cavity with or without ferrite inserts is explored both numerically and experimentally. The resonance frequencies and beam coupling impedances at cavity resonances are calculated with CST to understand the mode structure. The cavity transverse coupling impedances are also measured on a test stand using a two-wire method. We compare results of impedance calculations and measurements for a few different configurations, with and without ferrites, to ensure a complete understanding of the cavity resonances and their damping with ferrite. These results are important to provide adequate damping of undesired transverse modes in induction-linac cells.
	Poster MOPAB211 [1.105 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB211
About •	paper received ※ 10 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021
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MOPAB215	Using ICA for Retrieving Teng Parameters	GUI, factory, optics, FEL	711
	A. Lauterbach IAP, Frankfurt am Main, Germany G. Franchetti GSI, Darmstadt, Germany
	The blind source separation (BSS) method of Independent Component Analysis (ICA) is explored as a new approach for the reconstruction of the transfer matrix of Linear Coupling Parameterization. ICA is a method to detangle independent signals out of several measurements of their mixtures. In BSS-calculations, it is usually not possible to retrieve the mixing matrix, for the source signals, as well as the matrix, are unknown. Combining the parameterization model of D.A. Edwards and L.C. Teng with the standard ICA approach, it is though possible to retrieve the mixing matrix, as the form of the original uncoupled motion is known. At the same time arises the possibility to recalculate the parameters of Edwards and Teng through a system of equations of the one turn map components. It can be shown as a proof of concept, that the parameters can be reconstructed up to high accuracy for a simulated, non-perturbed signal.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB215
About •	paper received ※ 10 May 2021 paper accepted ※ 31 May 2021 issue date ※ 23 August 2021
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MOPAB226	Analytical Description of the Steerer Parameters in the Bilinear-Exponential Model at DELTA	betatron, storage-ring, closed-orbit, simulation	737
	S. Kötter DELTA, Dortmund, Germany
	At DELTA, a 1.5 GeV synchrotron radiation source operated by the TU Dortmund University, an analytical description of the steerer parameters in the bilinear-exponential (BE) model has been developed. The BE model describes the coupled orbit response in a storage ring. It is used in the closed-orbit bilinear-exponential analysis (COBEA) algorithm to decompose orbit response matrices into beta function, betatron phase, and a scaled dispersion. After introducing the BE model and the analytical steerer parameters, a simulation-based comparison of the BE model and another coupled orbit response model is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB226
About •	paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 11 August 2021
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MOPAB260	Optics Corrections with LOCO on Sirius Storage Ring	quadrupole, optics, storage-ring, MMI	825
	M.B. Alves LNLS, Campinas, Brazil
	Sirius is a 4th generation 3GeV synchrotron light source at the Brazilian Center for Research in Energy and Materials (CNPEM). In this work, we report the results of linear optics and coupling corrections during the commissioning of Sirius storage ring, using the Linear Optics from Closed Orbits (LOCO) algorithm. Beam-based measurements were performed to verify independently the impact of corrections on storage ring parameters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB260
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 30 August 2021
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MOPAB273	Nonlinear Coupling Resonances in X-Y Coupled Betatron Oscillations Near the Main Coupling Resonance in VEPP-2000 Collider	resonance, betatron, collider, experiment	863
	S.A. Kladov, E. Perevedentsev BINP SB RAS, Novosibirsk, Russia S.A. Kladov, E. Perevedentsev NSU, Novosibirsk, Russia
	In the vicinity of the linear coupling resonance where the working point of the collider is positioned, we study the effect of nonlinear coupling resonances on the single-particle phase space, beam sizes and the waveform of coherent beam motion. The latter is interesting for diagnostics of the nonlinear dynamics.
	Poster MOPAB273 [1.142 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB273
About •	paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 21 August 2021
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MOPAB274	Two-Stream Effects in Coherent Beam-Beam Oscillations in VEPP-2000 Collider Near the Linear Coupling Resonance	betatron, collider, synchrotron, resonance	866
	S.A. Kladov, E. Perevedentsev BINP SB RAS, Novosibirsk, Russia S.A. Kladov, E. Perevedentsev NSU, Novosibirsk, Russia
	Synchro-betatron motion of colliding bunches may cause limitations of the high-luminosity performance. For a round beam collider operated near the linear coupling resonance, we present theoretical predictions of the beam-beam coherent synchro-betatron oscillation behavior under the influence of x-y coupling.
	Poster MOPAB274 [0.968 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB274
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 02 September 2021
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MOPAB291	Design of Cavity BPM Pickup for EuPRAXIA@SPARC_LAB	cavity, GUI, pick-up, simulation	924
	Sh. Bilanishvili INFN/LNF, Frascati (Roma), Italy
	EuPRAXIA@SPARC_LAB will make available at LNF a unique combination offering three different options. A high-brightness electron beam with 1 GeV energy generated in a novel X-band RF linac; A PW-class laser system, and a compact light-source directly driven by a plasma accelerator. Plasma and conventional RF linac driven FEL provide beam with parameters of 30- 200pC charge range, 10-100Hz repetition rate, and 1 GeV electron energy. The control of the charge and the trajectory monitoring at a few pC and a few um is mandatory in this machine. Particularly in the plasma interaction region, where the pickup resolution under 1 um is required. As a possible solution, a cavity beam position monitor (cBPM) is proposed. A prototype in the C-band frequency range has been designed. The pickup was optimized for low charge and single-shot bunches. The poster presents the process to achieve the required specifications. The simulations were performed to study RF properties and the electromagnetic response of the device. Finally, the overall performance of the pickup is discussed, and theoretical resolution is approximated. https://www.researchgate.net/publication/335459394_From_SPARC_LAB_to_EuPRAXIASPARC_LAB **http://www.lnf.infn.it/sis/preprint/detail-new.php?id=5416
	Poster MOPAB291 [16.718 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB291
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 23 August 2021
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MOPAB326	Maximum Entropy Reconstruction of 4D Transverse Phase Space from 2D Projections: with Application to Laser Wire Measurements in the SNS HEBT	laser, emittance, neutron, linac	1008
	C.Y. Wong, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	We employ the principle of maximum entropy (MENT) to reconstruct 4D transverse phase space from its 2D projections. Emittance devices commonly measure two specific 2D projections, i.e. the horizontal and vertical phase space distributions. We show that: 1) given only these two 2D projections, their product is the analytic MENT solution to the 4D distribution; and 2) additional 2D projections provide information on inter-plane coupling in the MENT reconstruction of the 4D phase space which can be solved numerically. At the Spallation Neutron Source (SNS), laser wires in the high energy beam transport (HEBT) enable non-invasive two-slit type transverse phase space measurements. Laser wires play the role of the first slit whereas physical wires downstream of a drift act as the second slit. We reconstruct the 4D phase space in the HEBT using all four horizontal/vertical permutations of the two slits where: 1) the two configurations with parallel slits constitute ordinary 2D phase space measurements in either plane; and 2) the two configurations with perpendicular slits carry coupling information.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB326
About •	paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 17 August 2021
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MOPAB329	Operations of Copper Cavities at Cryogenic Temperatures	cavity, linac, cryogenics, ECR	1020
	H. Wang, U. Ratzinger, M. Schuett IAP, Frankfurt am Main, Germany
	How the anomalous skin effect by copper affects the efficiency of copper- cavities will be studied in the experiment, especially at lower temperatures. The accurate quality factor Q and resonant frequency of three coaxial cavities will be measured over the temperature range from 300 to 22 K. The three coaxial cavities have the same structure, but different lengths, which correspond to resonant frequencies: around 100 MHz, 220 MHz and 340 MHz. The motivation is to check the feasibility of an efficient pulsed, liquid nitrogen cooled ion linac.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB329
About •	paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 02 September 2021
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MOPAB330	Production and Performance Evaluation of a Compact Deflecting Cavity to Measure the Bunch Length in the cERL	cavity, resonance, vacuum, impedance	1023
	D. Naito, Y. Honda, T. Miyajima, N. Yamamoto KEK, Ibaraki, Japan
	At the KEK compact energy recovery linac, we try to generate an infrared free-electron laser (FEL). To generate the FEL, an electron bunch should be compressed along the longitudinal direction. The measurement of the bunch length is key to optimize the bunch compression. We plan to measure the bunch length by deflecting cavities in the burst mode. The deflecting cavities are required to be a time resolution of 33 fs in order to not only measure the bunch length but also resolve the structure inside the electron bunch. To achieve the requirement, we developed a c-band cavity whose RF input port is compact. The deflecting cavity is a single cell and normal conducting cavity. The deflection mode of the cavity is TM110. The 12 cavities will be located at the exit of undulators. In this presentation, we explain the design of our cavity and report the production of the first cavity. We also report the evaluation of the resonance frequency, the unloaded Q and the external Q of the cavity. From the measurements and simulations, the R/Q is estimated to be 1 mega orms. The time resolution of the cavity is expected to be 400 fs when the input RF power is 1 kW and the beam energy is 20 MeV.
	Poster MOPAB330 [12.920 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB330
About •	paper received ※ 12 May 2021 paper accepted ※ 08 June 2021 issue date ※ 28 August 2021
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MOPAB331	Design Consideration of a Longitudinal Kicker Cavity for Compensating Transient Beam Loading Effect in Synchrotron Light Sources	cavity, kicker, resonance, impedance	1027
	D. Naito, S. Sakanaka, T. Takahashi, N. Yamamoto KEK, Ibaraki, Japan T. Yamaguchi Sokendai, Ibaraki, Japan
	In ultra-low-emittance synchrotron light sources, bunch-lengthening using the combination of main and harmonic cavities is limited by the transient beam-loading (TBL) effect which is caused by gaps in the fill pattern. To manage this effect, we proposed a TBL compensation technique using a wide-band longitudinal kicker cavity. In the future KEK-LS storage ring, for example, the kicker cavity should provide a compensation voltage of 50 kV with a -3dB bandwidth (BW) of about 5 MHz, as well as its higher-order modes (HOM) should be damped sufficiently. In this presentation, we report our conceptual design of the kicker cavity. We employed the single-mode (SM) cavity concept so that harmful HOMs are dumped by rf absorbers on the beam pipes. The distinctive feature of the SM cavity is its simple structure since it has no HOM damper on the cavity. Another feature is its low R/Q by which the TBL effect in the kicker cavity itself can be reduced significantly. We employed a frequency of 1.5 GHz (third-harmonic) and R/Q of 60 orms through optimizations. Using this kicker cavity with a double rf system, a bunch lengthening by a factor of 4.3 (i.e., 40.9 ps) is expected for the KEK-LS case. N.Yamamoto et al., Phys. Rrev. Acc. Beams 21, 012001 (2018)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB331
About •	paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 01 September 2021
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MOPAB332	Design of 4th Harmonic RF Cavities for ESRF-EBS	HOM, cavity, SRF, impedance	1031
	A. D’Elia, J. Jacob, V. Serrière, X.W. Zhu ESRF, Grenoble, France
	Funding: European Union’s Horizon 2020 research and innovation program under grant #871072 An active 4th harmonic RF system for bunch lengthening is under study at the ESRF to improve the performance of the new EBS storage ring, mainly for few bunch operation with high currents per bunch, by reducing Touschek and intrabeam scattering, thereby increasing the lifetime and limiting the emittance growth. It will also reduce impedance heating of the vacuum chambers. The 4th Harmonic 1.41 GHz normal conducting cavity design takes inspiration from the KEK idea of using a TM020 mode exhibiting a reduced R/Q but a higher unloaded Q with respect to TM010. We propose to use multicell cavities for their compactness, the reduced number of required ancillaries and the ease of control for a reduced number of cavities. The drawback is the complexity of the model and the necessity to damp the lower order TM010 mode (LOM) as well as the higher order modes (HOM). The RF design of a 4th harmonic multicell damped cavity will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB332
About •	paper received ※ 19 May 2021 paper accepted ※ 17 August 2021 issue date ※ 16 August 2021
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MOPAB339	Design Of An X-band 3MeV Standing-wave Accelerating Structure with Nose-cone Structure Made From Two Halves	impedance, cavity, electron, bunching	1051
	F. Liu, H.B. Chen, J. Shi, C.-X. Tang, H. Zha TUB, Beijing, People’s Republic of China
	This work presents an X-band 3MeV standing-wave accelerating structure with nose cones made from two halves. Milling two longitudinally split halves is one economic method to manufacture accelerating structure for decrease of welding, with increasing the difficulty in machining. This linear accelerator includes 4 buncher cavities and 4 accelerating cavities, and nose cone is applied to achieve high shunt impedance. A technical prototype is under fabrication to bring two milled halves manufacture way into practical application.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB339
About •	paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 15 August 2021
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MOPAB343	Optimization of the Parasitic-Mode Damping on the 1.5 GHz TM020-type Harmonic Cavity	cavity, damping, impedance, simulation	1064
	T. Yamaguchi Sokendai, Ibaraki, Japan D. Naito, S. Sakanaka, T. Takahashi, N. Yamamoto KEK, Ibaraki, Japan
	Bunch-lengthening harmonic cavity is one of the essential tools to mitigate the intrabeam scattering in the 4th-generation synchrotron light sources. For this purpose, we proposed a normal-conducting 1.5 GHz harmonic cavity* of TM020-type*. Thanks to its low R/Q (68 ohms) and high unloaded Q (34, 000), bunch gap transient in the harmonic cavity can be reduced to ~20% as compared to that in a typical TM010 cavity. Furthermore, harmful parasitic modes in this cavity can be heavily damped by installing ferrites where no magnetic fields of TM020-mode exist. However, some of the parasitic modes, e.g. TM021 and TM120 modes, are difficult to damp because their field patterns are similar to that of the TM020 mode. To damp such modes effectively, we optimized the cavity inner shape by tailoring the curvature at the cavity equator, the shape of the nose cones, and introducing "bumps" on the inner wall. Our goals of the coupling impedances are fxR < 2.4[kohm GHz] and RT < 23 kohm/m in the longitudinal and the transverse planes, respectively. As a result of optimization, we almost achieved these goals. To confirm our simulation results, fabrication of a low-power test cavity is in progress. N . Yamamoto et al., Phys. Rev. Acc. Beams 21, 012001 (2018). ** H. Ego et al., Proc. of the 11th Annual Meeting of Particle Accelerator Society of Japan (PASJ2014), MOOL14 (2014).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB343
About •	paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 01 September 2021
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MOPAB353	Design of a compact Ka-Band Mode Launcher for High-gradient Accelerators	cavity, simulation, quadrupole, accelerating-gradient	1100
	G. Torrisi, G.S. Mauro, G. Sorbello INFN/LNS, Catania, Italy M. Behtouei, L. Faillace, B. Spataro, A. Variola INFN/LNF, Frascati, Italy V.A. Dolgashev SLAC, Menlo Park, California, USA L. Faillace, M. Migliorati Sapienza University of Rome, Rome, Italy M. Migliorati INFN-Roma1, Rome, Italy J.B. Rosenzweig UCLA, Los Angeles, California, USA G. Sorbello University of Catania, Catania, Italy
	In this work, we present the RF design of a table-top Ka-Band mode launcher operating at 35.98 GHz. The structure consists of a symmetrical 4-port WR28 rectangular-TE10-to-circular-TM01 mode converter that is used to couple a peak output RF power of 5 MW (pulse length up to 50 ns and repetition rate up to 100 Hz) in Ka-Band linear accelerator able to achieve very high accelerating gradients (up to 200 MV/m). Numerical simulations have been carried out with the 3D full-wave commercial simulator Ansys HFSS in order to obtain a preliminary tuning of the accelerating field flatness at the operating frequency f0=35.98 GHz. The main RF parameters, such as reflection coefficient, transmission losses, and conversion efficiency are given together with a verification of the field azimuthal symmetry which avoids dipole and quadrupole deflecting modes. To simplify future manufacturing, reduce fabrication costs, and also reduce the probability of RF breakdown, the proposed new geometry has "open" configuration. This geometry eliminates the flow of RF currents through critical joints and allows this device to be milled from metal blocks.
	Poster MOPAB353 [3.131 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB353
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 27 August 2021
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MOPAB362	Atomistic Modeling of the Coupling Between Electric Fields and Bulk Plastic Deformation in Rf Structures	simulation, experiment, feedback, framework	1125
	S. Bagchi, D. Perez LANL, Los Alamos, New Mexico, USA
	Funding: LANL-LDRD A notable bottleneck in achieving high-gradient RF technology is dictated by the onset of RF breakdown. While bulk mechanical properties are known to significantly affect breakdown propensity, the underlying mechanisms coupling RF fields to bulk plastic deformation in experimentally relevant thermo-electrical loading conditions remain to be identified at the atomic scale. Here, we present results of large-scale molecular dynamics simulations (MD) to investigate possible modes of coupling. We consider the activation of Frank-Read (FR) sources, which leads to dislocation multiplication, under the action of bi-axial thermal stresses and surface electric-field. With a charge-equilibration formalism incorporated in a classical MD model, we show that a surface electric field acting on an either preexisting or dislocation-induced surface step, can generate a long-range resolved shear stress field inside the bulk of the sample. We investigate the feedback between step growth following dislocation emission and subsequent activations of FR sources and discuss the regimes of critical length-scales and densities of dislocations, where such a mechanism could promote RF breakdown precursors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB362
About •	paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 19 August 2021
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MOPAB364	Shielded Pair Method for Cylindrical Surface Resistance Measurement at Cryogenic Temperature	factory, cryogenics, dipole, simulation	1132
	K. Brunner, S. Calatroni, F. Caspers CERN, Geneva, Switzerland D. Barna Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary
	The shielded pair resonator method was already used in the past at CERN to measure the surface resistivity of the LHC beam screen both at room temperature and cryogenic temperature. We have refined and adapted the measurement to be able to measure other types of beam screens and also to operate in a strong dipolar magnetic field. This is necessary for testing the properties of HTS coated beam screens or the possible effects of coatings and surface treatments for e-cloud suppression. Several calibration runs were done at cryogenic temperatures (4.2 K) measuring the surface resistivity of a copper pipe to identify the precision, stability and reproducibility achievable using this method. This work describes the challenges of the measurement and ways to mitigate them.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB364
About •	paper received ※ 17 May 2021 paper accepted ※ 22 June 2021 issue date ※ 12 August 2021
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MOPAB371	A Coupon Tester for Normal Conducting High-Gradient Materials	cavity, vacuum, RF-structure, klystron	1147
	J.W. Lewellen, D. Gorelov, D. Perez, E.I. Simakov LANL, Los Alamos, New Mexico, USA M.E. Schneider Michigan State University, East Lansing, Michigan, USA
	Funding: Los Alamos National Laboratory LDRD Program A coupon tester is an RF structure used to subject a material sample to very high RF fields, with the fields on the sample, or coupon, being higher than elsewhere in the cavity. To date, most such cavities were originally intended to explore the RF properties of superconducting materials, and can expose the sample to strong magnetic fields, but weak to no electric fields. As part of a program to develop materials and structures for high-gradient (> 100 MV/m), low-breakdown-rate normal-conducting accelerators, we have designed a C-band (5.712 GHz) cavity intended to subject samples to both magnetic and electric fields comparable to those experienced in high-gradient structure designs, using a TM-mode cavity; the electric and magnetic fields along the sample coupon can be directly compared to the fields on the iris of high-gradient structures. This poster will present the design criteria for our coupon tester cavity, nominal operating parameters, and our structure concept. The cavity design will be refined over the next several months, and will be constructed and in service near the start of 2022.
	Poster MOPAB371 [0.764 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB371
About •	paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 30 August 2021
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TUPAB006	The Impact of Beam Position Monitor Tilts on Coupling Measurements	resonance, optics, simulation, quadrupole	1342
	L. van Riesen-Haupt, R. Tomás García CERN, Meyrin, Switzerland
	The measurement and correction of coupling resonance driving terms is a key tool for improving the performance of synchrotrons. These terms are measured by exciting the beam and observing the subsequent motion in the horizontal and vertical planes through beam position monitors. This paper outlines the impact of tilt errors in these monitors to the distortion of the amount of coupling measured between the planes and how the computation of the resonance driving terms is affected by these tilts. It also attempts to use these results for mimicking tilt errors in simulations and discusses how discrepancies in measured resonance driving terms could be used to estimate the tilt errors that cause them.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB006
About •	paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 12 August 2021
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TUPAB016	ESS RFQ: Installation and Tuning at Lund	rfq, quadrupole, insertion, cavity	1372
	P. Hamel, D. Chirpaz-Cerbat, M. Desmons, A.C. France, O. Piquet CEA-IRFU, Gif-sur-Yvette, France A. Dubois, Y. Le Noa CEA-DRF-IRFU, France
	The 352 MHz Radio Frequency Quadrupole (RFQ) for the European Spallation Source ERIC (ESS) has been delivered by the end of 2019. It has been provided by CEA, IRFU, Saclay/France. It consists of five sections with a total length of 4.6 m and accelerates the 70 mA proton beam from 75 keV up to 3.6 MeV. It will be fed with 900 kW peak power through two coaxial loop couplers. The installation process (alignment, vacuum test), as well as the tuning process based on bead-pull measurements, is presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB016
About •	paper received ※ 18 May 2021 paper accepted ※ 06 July 2021 issue date ※ 14 August 2021
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TUPAB041	Detector Solenoid Compensation for the Electron-Ion Collider	solenoid, electron, detector, cavity	1439
	B.R. Gamage, T.J. Michalski, V.S. Morozov, R. Rajput-Ghoshal, A. Seryi, W. Wittmer, Y. Zhang JLab, Newport News, Virginia, USA E. Gianfelice-Wendt Fermilab, Batavia, Illinois, USA A. Kiselev, H. Lovelace III, B. Parker, S. Peggs, S. Tepikian, F.J. Willeke, H. Witte, Q. Wu BNL, Upton, New York, USA
	Funding: Jefferson Science Associates, LLC Contract No. DE-AC05-06OR23177, Fermi Research Alliance, LLC Contract No. DE-AC02-07CH11359, and Brookhaven Science Associates, LLC Contract No. DE-SC0012704 The central detector in the present EIC design includes a 4 m long solenoid with an integrated strength of up to 12 Tm. The electron beam passes on-axis through the solenoid, but the hadron beam has an angle of 25 mrad. Thus the solenoid couples horizontal and vertical betatron motion in both electron and hadron storage rings, and causes a vertical closed orbit excursion in the hadron ring. The solenoid also couples the transverse and longitudinal motions of both beams, when crab cavities are also considered. In this paper, we present schemes for closed orbit correction and coupling compensation at the IP, including crabbing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB041
About •	paper received ※ 28 May 2021 paper accepted ※ 31 August 2021 issue date ※ 12 August 2021
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TUPAB051	Elettra and Elettra 2.0	emittance, insertion, insertion-device, status	1474
	E. Karantzoulis, A. Carniel, D. Castronovo, S. Di Mitri, B. Diviacco, S. Krecic Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with the future upgrade concerning the new ultra-low emittance light source Elettra 2.0 that will provide ultra-high brilliance while the very short pulses feasibility study for time resolved experiments is in progress.
	Poster TUPAB051 [1.632 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB051
About •	paper received ※ 10 May 2021 paper accepted ※ 27 May 2021 issue date ※ 20 August 2021
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TUPAB054	CDR BASELINE LATTICE FOR THE UPGRADE OF SOLEIL	lattice, emittance, injection, photon	1485
	A. Loulergue, D. Amorim, P. Brunelle, A. Gamelin, A. Nadji, L.S. Nadolski, R. Nagaoka, R. Ollier, M.-A. Tordeux SOLEIL, Gif-sur-Yvette, France
	Previous MBA studies converged toward a lattice composed of 20 7BA solution elaborated by adopting the sextupole pairing scheme with dispersion bumps originally developed at the ESRF-EBS. It provided a low natural horizontal emittance value of 70-80 pm-rad range at an energy of 2.75 GeV. Due to difficulties to accommodate such lattice geometry in the SOLEIL present tunnel as well as to preserve at best the beamline positioning, alternative lattice based on HOA (Higher-Order Achromat) type cell has been recently investigated. The HOA type cell being more modular and possibly exhibiting larger momentum acceptance as well as low emittances, a solution alternating 7BA and 4BA cells was then identified as the best to adapt the current beamline positioning. The SOLEIL CDR upgrade reference lattice is then composed of 20 HOA cells alternating 7BA and 4BA giving a natural horizontal emittance of 80 pm-rad. The linear and non-linear beam dynamic properties of the lattice along with the possibility of horizontal off-axis injection at full betatron coupling are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB054
About •	paper received ※ 21 May 2021 paper accepted ※ 02 July 2021 issue date ※ 10 August 2021
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TUPAB077	Novel Open Cavity for Rotating Mode SLED-Type RF Pulse Compressors	cavity, klystron, GUI, linear-collider	1547
	X.W. Wu, A. Grudiev CERN, Meyrin, Switzerland
	A new X-band high-power rotating mode SLAC Energy Doubler (SLED)-type rf pulse compressor is proposed. It is based on a novel cavity type, a single open bowl-shape energy storage cavity with high Q₀ and compact size, which is coupled to the waveguide using a compact rotating mode launcher. The novel cavity type is applied to the rf pulse compression system of the main linac rf module of the klystron-based option of the Compact Linear Collider (CLIC). Quasi-spherical rotating modes of \rm{TE}_1,2,4 and \rm{TE}_1,2,13 are proposed for the correction cavity and storage cavity of the rf pulse compression system respectively. The storage cavity working at \rm{TE}_1,2,13 has a Q₀ of 240000 and a diameter less than 33 cm. The design of the pulse compressor and in particular of the high-Q cavity will be presented in detail.
	Poster TUPAB077 [1.229 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB077
About •	paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 27 August 2021
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TUPAB133	Brazing free RF Pulse Compressor for High Gradient Accelerators	GUI, cavity, simulation, vacuum	1700
	L. Kankadze, D. Alesini, F. Cardelli, G. Di Raddo, M. Diomede INFN/LNF, Frascati, Italy
	EURPRAXIA@SPARC\_LAB, is a proposal to upgrade the SPARC\_LAB test facility (at LNF, Frascati) to a soft X-ray user facility based on plasma acceleration and high-gradient X-band (11.9942 GHz) accelerating modules. Each module is made up of a group of 4 TW sections assembled on a single girder and fed by one klystron by means of one rf pulse compressor system and a low attenuation circular waveguide network that transports the rf power to the input hybrids of the sections. The pulse compressor is based on a single Barrel Open Cavity (BOC). The BOC use a ’whispering gallery’ mode which has an intrinsically high quality factor and operates in a resonant rotating wave regime. Compared to the conventional SLED scheme it requires a single cavity instead of two cavities and a 3-dB hybrid. A new brazeless mechanical design has been proposed and is described in the present paper together with the electro-magnetic and thermo-mechanical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB133
About •	paper received ※ 21 May 2021 paper accepted ※ 15 June 2021 issue date ※ 10 August 2021
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TUPAB170	Decouple Transverse Coupled Beam in the DTL with Tilted PMQs	emittance, DTL, rfq, cavity	1785
	P.F. Ma, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng TUB, Beijing, People’s Republic of China Y.H. Pu, J. Qiao, C.P. Wang, X.C. Xie, F. Yang Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China
	The coupling of the beam is widely studied in the accelerator physics field. Projected transverse emittances easily grow up if the beam is transversely-coupled. If we decouple the transverse coupled beam, the transverse emittance can be small. The matrix approach based on the symplectic transformation theory for decoupling the coupled beam is summarized. For a proton accelerator, the transverse coupled beam is introduced by an RFQ tilted by 45°. The beam is decoupled with the first five tilted quadrupoles mounted in the DTL section. A study on the gradient choice of the quadrupoles and the space charge effect is given in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB170
About •	paper received ※ 08 May 2021 paper accepted ※ 21 June 2021 issue date ※ 28 August 2021
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TUPAB171	Linear Transfer Matrix of a Half Solenoid	solenoid, emittance, optics, ion-source	1789
	P.F. Ma, X. Guan, X.W. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng TUB, Beijing, People’s Republic of China
	Solenoid magnets can provide strong transverse focusing to electrons and ions with relatively small energies. For the ECR heavy-ion source, the ions are extracted at the central area of the solenoid, the beam is coupled at the exit of the source. The coupling caused by the solenoids can lead to the growth of projected transverse emittance, which has been widely studied with great interest. It is important to study the transfer matrix of a half solenoid to study the beam optics in an ECR souce, thus the property of the beam can be given. Based on the transfer matrix calculation, the summary of the linear transfer matrix of a half solenoid can be given. The beam optics in a half solenoid is studied.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB171
About •	paper received ※ 18 May 2021 paper accepted ※ 28 June 2021 issue date ※ 29 August 2021
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TUPAB232	Linear Coupling and Adiabaticity of Emittance Exchange	resonance, emittance, extraction, proton	1972
	F. Capoani, M. Giovannozzi CERN, Geneva, Switzerland A. Bazzani, F. Capoani Bologna University, Bologna, Italy A.I. Neishtadt IKI, Moscow, Russia A.I. Neishtadt Loughborough University, Leicestershre, United Kingdom
	In circular accelerators, crossing the coupling resonance induces the exchange of the transverse emittances, provided the process is adiabatic. In this paper, we introduce a theoretical framework to analyze the resonance-crossing process, based on Hamiltonian mechanics, which is capable of explaining all the features of the emittance exchange process.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB232
About •	paper received ※ 11 May 2021 paper accepted ※ 16 June 2021 issue date ※ 27 August 2021
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TUPAB242	The Beam-Study of the Side and On-Axis RF Cavities in S-Band 6 MeV LINACs	cavity, target, emittance, impedance	2008
	A. Khosravi, B. Shokri LAPRI, Tehran, Iran N. Khosravi ILSF, Tehran, Iran
	The geometry of side and on-axis RF cavities are two magnetic-coupled designs for the different LINAC applications. The electromagnetic fields, RF power, beam parameters, thermal stability, and manufacturing costs are the most critical factors in cavity type selection in each application. In this article, both RF-cavities are optimized in POISSON SUPERFISH code to compare the beam parameters accurately. Then the optimized cavities are making a tube and compare in ASTRA 1D code and CST 3D software. At last, the thermal sensitivity of both models is studied in MPHYSICS module of the CST. As a result, the final decision can be achieved on the side or on-axis cavities considering the input power, costs, beam properties, and thermal stability for the different applications of the LINACs
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB242
About •	paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021
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TUPAB258	Impact of Coherent Beam-Beam Interaction on the Landau Damping of the Transverse Coupled-Bunch Instability	dipole, electron, damping, proton	2062
	R. Li JLab, Newport News, Virginia, USA M. Blaskiewicz BNL, Upton, New York, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. In the EIC design, at high average-current operation, the transverse coupled-bunch instability (TCBI) induced by the long-range transverse resistive-wall wakefield in the electron storage ring (eSR) has a fast growth rate and requires efficient mitigation. A natural mitigation mechanism is provided by the beam-beam interaction at the interaction point (IP), which gives a strong Landau damping for the TCBI in the eSR. In this study, using a simplified simulation model, we investigate how this Landau damping from the beam-beam interaction behaves when the coherent beam-beam interaction at IP is considered. Our method and results will be presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB258
About •	paper received ※ 21 June 2021 paper accepted ※ 01 July 2021 issue date ※ 25 August 2021
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WEPAB026	Optics Measurements and Correction Plans for the HL-LHC	optics, luminosity, dynamic-aperture, dipole	2656
	T.H.B. Persson, X. Buffat, F.S. Carlier, R. De Maria, J. Dilly, E. Fol, D. Gamba, H. Garcia Morales, A. García-Tabarés Valdivieso, M. Giovannozzi, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, P.K. Skowroński, F. Soubelet, R. Tomás García, F.F. Van der Veken, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt CERN, Geneva, Switzerland J.M. Coello de Portugal PSI, Villigen PSI, Switzerland
	The High Luminosity LHC (HL-LHC) will require stringent optics correction to operate safely and deliver the design luminosity to the experiments. In order to achieve this, several new methods for optics correction have been developed. In this article, we outline some of these methods and we describe the envisioned strategy of how to use them in order to reach the challenging requirements of the HL-LHC physics program.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB026
About •	paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 30 August 2021
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WEPAB027	Optics Correction Strategy for Run 3 of the LHC	optics, dipole, MMI, quadrupole	2660
	T.H.B. Persson, R. De Maria, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, F. Soubelet, R. Tomás García, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt CERN, Geneva, Switzerland J.F. Cardona UNAL, Bogota D.C, Colombia
	The Run 3 of the LHC will continue to provide new challenges for optics corrections. In order to succeed and go beyond what was achieved previously, several new methods to measure and correct the optics have been developed. In this article we describe these methods and outline the plans for the optics commissioning in 2022.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB027
About •	paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021
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WEPAB148	RF Design of an X-Band TM02 Mode Cavity for Field Emitter Testing	cavity, electron, insertion, multipactoring	2961
	Z. Li, S.G. Tantawi SLAC, Menlo Park, California, USA S.V. Baryshev, T. Posos, M.E. Schneider Michigan State University, East Lansing, Michigan, USA
	Funding: Work at SLAC was supported by DOE under contract No. DE-AC02-76SF00515. Work at MSU was supported by DOE under Award No. DE-SC0020429 and under Cooperative Agreement Award No. DE-SC0018362. Planar polycrystalline synthetic diamond with nitrogen-doping/incorporation was found to be a remarkable field emitter. It is capable of generating a high charge beam and handling moderate vacuum conditions. Integrating it with an efficient RF cavity could therefore provide a compact electron source for RF injectors. Understanding the performance metrics of the emitter in RF fields is essential toward developing such a device. We investigated a test setup of the field emitter at the X-band frequency. The setup included an X-band cavity operating at the TM02 mode. The field emitter material will be plated on the tip of a insertion rod on the cavity back plate. Part of the back plate and the emitter rod are demountable, allowing for exchange of the field emitters. The TM02 mode was chosen such that the design of the demountable back plate does not induce field enhancement at the installation gap. The cavity were optimized to achieve a high surface field at the emitter tip and a maximum energy gain of the emitted electrons at a given input power. We will present the RF and mechanical design of such a TM02 X-band cavity for field emitter testing.
	Poster WEPAB148 [1.642 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB148
About •	paper received ※ 14 May 2021 paper accepted ※ 12 July 2021 issue date ※ 12 August 2021
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WEPAB164	Electrodeless Diamond Beam Halo Monitor	electron, experiment, radiation, vacuum	2990
	S.V. Kuzikov, S.P. Antipov, P.V. Avrakhov, E. Dosov, E.W. Knight, Y. Zhao Euclid TechLabs, Solon, Ohio, USA J.G. Power, J. Shao ANL, Lemont, Illinois, USA
	Funding: This work was supported by DoE SBIR grant # DE-SC0019642. Beam halo measurement is important for novel x-ray free-electron lasers which have remarkably high repetition rate and average power. We propose diamond as a radiation hard material that can be used to measure the flux of passing particles based on a particle-induced conductivity effect. Our diamond electrodeless monitor is based on a microwave measurement of the change in the resonator coupling and eigenfrequency. For measurements, we put a sensitive diamond sample in a resonator that intercepts the halo. By measuring the change in RF properties of the resonator, one can infer the beam halo parameters scanning across the beam to map its transverse distribution. In recent experiments we used a Vertical Beam Test Stand (VBS), delivered DC electron beam of the 20-200 keV energy with the current up to 50 µA, to characterize several diamond samples. We have designed and fabricated a scanning diamond monitor, based on an X-band resonator, which was tested at Argonne Wakefield Accelerator (AWA) with a multi-MeV electron beam.
	Poster WEPAB164 [5.138 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB164
About •	paper received ※ 14 May 2021 paper accepted ※ 07 June 2021 issue date ※ 31 August 2021
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WEPAB195	Design and Optimization of a Low Frequency RF-Input Coupler for the IsoDAR RFQ	rfq, simulation, cyclotron, multipactoring	3081
	M.P. Sangroula, J.M. Conrad, D. Winklehner MIT, Cambridge, Massachusetts, USA M. Schuett BEVATECH, Frankfurt, Germany
	Funding: The RFQ-DIP project is supported by National Science Foundation grant \# PHY-1626069 and the Heising-Simons Foundation. The Isotope Decay-At-Rest experiment (IsoDAR) is a proposed underground experiment which is expected to be a definitive search for sterile neutrinos. IsoDAR uses an especially designed low-frequency spilt-coaxial radio frequency quadrupole (RFQ) to accelerate H²⁺ ions directly from the ion source into the main cyclotron accelerator. This paper mainly focuses on the design and optimization of a low frequency (32.8 MHz) RF-input coupler for the IsoDAR RFQ. Starting with a basic design, we determine its appropriate position for this coupler in the RFQ. Finally, we optimized the design to lower the input power without compromising the coupling efficiency.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB195
About •	paper received ※ 21 May 2021 paper accepted ※ 30 June 2021 issue date ※ 29 August 2021
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WEPAB225	Transverse and Longitudinal Single Bunch Instabilities in FCC-ee	wakefield, impedance, simulation, collider	3153
	E. Carideo, D. Quartullo, F. Zimmermann CERN, Geneva, Switzerland D. De Arcangelis Sapienza University of Rome, Rome, Italy M. Migliorati, M. Zobov INFN/LNF, Frascati, Italy
	Improving the accuracy of the impedance model of an accelerator is important for keeping beam instabilities and power loss under control. Here, by means of the PyHEAD- TAIL tracking code, we first review the longitudinal mi- crowave instability threshold for FCC-ee by taking into ac- count the longitudinal impedance model evaluated so far. Moreover, we present the results of beam dynamics simula- tions, including both the longitudinal and transverse wake- fields due to the resistive wall, in order to evaluate the influ- ence of the bunch length on the transverse mode coupling instability. The results of the transverse beam dynamics are also compared with the Vlasov solver DELPHI.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB225
About •	paper received ※ 10 May 2021 paper accepted ※ 01 July 2021 issue date ※ 18 August 2021
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WEPAB227	Mechanism of Longitudinal Single-Bunch Instability in the CERN SPS	impedance, simulation, synchrotron, emittance	3161
	I. Karpov CERN, Meyrin, Switzerland M. Gadioux UCD, Dublin, Ireland
	Understanding the origin of beam instabilities is essential for reaching the highest performance of proton synchrotrons. In the present work, the Oide-Yokoya eigenvalue method of solving the linearised Vlasov equation was used to shed light on the mechanism of longitudinal single-bunch instability in the CERN SPS. In particular, semi-analytical calculations were done for the full longitudinal impedance model, taking into account the RF nonlinearity. The obtained results agree well with macro-particle simulations and are consistent with available beam measurements. For the first time, the instability has been interpreted as a coupling of radial modes within a single azimuthal mode, due to a strong potential-well distortion of the synchrotron-frequency distribution. To avoid this instability, a higher RF voltage is required at a given emittance. Thus, the instability mechanism is very different from the loss of Landau damping, which, in contrast, is mitigated by a lower RF voltage. This understanding also allowed us to optimise the RF voltage programmes during the acceleration cycle for high-intensity bunches used in the AWAKE experiment at CERN.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB227
About •	paper received ※ 12 May 2021 paper accepted ※ 01 July 2021 issue date ※ 15 August 2021
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WEPAB235	TMCI Theory of Flat Chambers Revisited	impedance, storage-ring, vacuum, simulation	3181
	T.F. Günzel ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	By accounting for the transverse impedance’ quadrupolar component according to the work of R.Lindberg , no TMCI-instability can be observed in case of a pure horizontal resistive wall impedance of flat vacuum chambers. In order to study this effect more closely, TMCI-theory is reviewed and Lindberg’s work is further developed by including the resonator model as impedance type. The theory is applied to the ALBA-impedance model for the calculation of horizontal TMCI-detuning and threshold. Moreover, a couple of example cases are presented including vertical TMCI-detuning and threshold. Results on both planes are compared to simpler descriptions which account for the quadrupolar impedance effect only by tune shift. Ryan Lindberg, Fokker-Planck analysis of transverse collective instabilities in electron storage rings, Phy. Rev. Acc. Beams 19, 124402 (2016)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB235
About •	paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 19 August 2021
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WEPAB239	Effect of Chromaticity and Feedback on Transverse Head-Tail Instability	feedback, impedance, damping, storage-ring	3189
	V.V. Smaluk, G. Bassi, A. Blednykh, A. Khan BNL, Upton, New York, USA
	Funding: This work was supported by the US Department of Energy under contract DE-SC0012704. The head-tail instability caused by the beam interaction with short-range wakefields is a major limitation for the single-bunch beam intensity in circular accelerators. The combined effect of the transverse feedback systems and chromaticity suppressing the instability is discussed. Theoretical and experimental studies of the head-tail instability and methods of its mitigation are reviewed. Results of experimental studies of the transverse mode coupling carried out at NSLS-II are compared with the theoretical model and numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB239
About •	paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 12 August 2021
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WEPAB279	On Wire-Corrector Optimization in the HL-LHC and the Appearance of Special Aspect Ratios	target, optics, insertion, resonance	3297
	D. Kaltchev TRIUMF, Vancouver, Canada
	For the two high-luminosity insertions of the Large Hadron Collider (HL-LHC) current bearing wire correctors are intended to mitigate the detrimental effect of long-range beam-beam interactions. With respect to finding the optimum longitudinal location of the wire, two special locations corresponding to the special values 2 and 1/2 of the beta-function aspect ratio have been previously shown to provide simultaneous cancellation of multiple two-dimensional Resonance Driving Terms. This paper attempts to explain the appearance of such special aspect ratios.
	Poster WEPAB279 [1.238 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB279
About •	paper received ※ 14 May 2021 paper accepted ※ 19 July 2021 issue date ※ 13 August 2021
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WEPAB295	Parameter Estimation of Short Pulse Normal-Conducting Standing Wave Cavities	cavity, gun, RF-structure, resonance	3351
	S. Pfeiffer, J. Branlard, F. Burkart, M. Hoffmann, H. Schlarb DESY, Hamburg, Germany
	The linear accelerator ARES (Accelerator Research Experiment at SINBAD) is a new research facility at DESY. Electron bunches with a maximum repetition rate of 50 Hz are accelerated to a target energy of 155 MeV. The facility aims for ultra-stable sub-femtosecond arrival-times and high peak-currents at the experiment, placing high demands on the reference distribution and field regulation of the RF structure. In this contribution, we present the physical parameter estimation of key RF properties such as cavity detuning not directly measurable on the RF field decay. The method can be used as a fast monitor of inner cell temperature. The estimated properties are finally compared with the measured ones.
	Poster WEPAB295 [0.860 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB295
About •	paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 26 August 2021
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WEPAB329	LCLS-II Average Current Monitor	cavity, vacuum, simulation, network	3443
	P. Borchard, J.S. Hoh Dymenso LLC, San Francisco, USA
	The LCLS-II project at SLAC is a high power upgrade to the existing free-electron laser facility. The LCLS-II Accelerator System will include a new 4 GeV continuous-wave superconducting linear accelerator in the first kilometer of the SLAC linear accelerator tunnel and supplements the existing low power pulsed linac. Average Current Monitors (ACMs) are needed to protect against excessive beam power which might otherwise cause damage to the beam dumps. The ACM cavities are pillbox-shaped stainless steel RF cavity with two radial probe ports with couplers, one radial test port with a coupler, and a mechanism for mechanically fine-tuning the cavity resonant frequency. The ACM RF cavities will be located at points of known or constrained beam energy and will monitor the beam current, a safety system will trip off the beam if the beam power exceeds the allowed value.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB329
About •	paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 22 August 2021
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WEPAB342	Beam Induced Power Deposition in CERN SPS Injection Kickers	impedance, simulation, HOM, kicker	3490
	M.J. Barnes, O. Bjorkqvist CERN, Geneva 23, Switzerland K. Kodama KEK, Ibaraki, Japan
	The SPS injection kicker magnets (MKP) were developed in the 1970’s, before beam power deposition was considered an issue and before any advanced tools for analysing beam coupling impedance were available in their current form. These magnets are very lossy from a beam impedance perspective, and the beam induced power deposition is highly non-uniform. This is expected to be an issue during SPS operation with the higher intensity beams needed in the future for HL-LHC. There is an existing design, with serigraphy, that will mitigate the heating issues, which is presently being implemented on a prototype for test and measurement. Models have been developed to aid in predicting the safe operating regions until the upgraded MKPs are installed in the SPS: these are reported herein. A novel measurement technique is also presented to confirm the non-uniform power deposition in the ferrite yoke. Beam coupling impedance, power deposition, field rise time and field uniformity data are also presented for an upgraded, prototype, MKP.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB342
About •	paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 25 August 2021
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WEPAB345	Impedance and Thermal Studies of the LHC Injection Kicker Magnet Upgrade	kicker, impedance, injection, simulation	3502
	M.J. Barnes, O. Bjorkqvist, F. Motschmann CERN, Geneva 23, Switzerland
	The bunch intensities of High Luminosity (HL) LHC are predicted to lead to heating of the ferrite yokes of the LHC injection kicker magnets (MKI), in their current configuration, to their Curie temperature. Hence, the MKIs are being upgraded to meet the requirements of HL-LHC, which is planned to start in the mid-2020s. The upgraded design features an RF damping ferrite loaded structure at the upstream end of each magnet, which will absorb a large portion of the beam induced power deposition of the magnet. The ferrite damper is cooled via a copper sleeve, brazed to the ferrite, and a set of water pipes. The thermal contact conductance (TCC) between ferrite and copper is very important, as are the properties of the ferrite. In this paper, we present measurements of the TCC and ferrite properties. This data is used to predict temperatures during operation of the LHC. In addition, a measurement and prediction is shown for the longitudinal impedance of the magnet. The models developed in this study will be benchmarked during run III of the LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB345
About •	paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 13 August 2021
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WEPAB346	Electromagnetic Modelling of Kicker Magnets to Derive Equivalent Circuits	kicker, simulation, impedance, extraction	3506
	M.J. Barnes, O. Bjorkqvist CERN, Geneva 23, Switzerland L. Jensen, O.A. Nielsen Aarhus University, Aarhus, Denmark
	An equivalent circuit model of a kicker magnet system is an invaluable tool for predicting the performance, studying possible modifications and for helping to diagnose faults. The frequency content of pulses associated with a ferrite loaded transmission line kicker magnet generally extend up to a few tens of MHz: hence, it is feasible to accurately model such a kicker magnet using lumped elements. This modelling technique is powerful since it in general has a run time several orders of magnitude shorter than a full wave electromagnetic simulation. In this paper, we determine values, including those of parasitic components, using modern simulation tools, for use in the lumped equivalent circuit models. In addition, the paper describes a method to simulate coupling between beam and the electrical circuit of a kicker magnet at relatively low frequencies: this allows one to use circuit analysis tools to study means of mitigating beam induced resonances.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB346
About •	paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 14 August 2021
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WEPAB349	Design of a Circular Waveguide TM₀₁ Mode Launcher with Wire Loop Feed	GUI, experiment, detector, simulation	3517
	A. Chittora BITS Pilani, Sancoale, India
	In Accelerator technology, RF power couplers are important component to couple RF signal to travelling wave structure. Circular waveguide TM₀₁ mode is one of the symmetric modes, that is suitable to use for RF coupling. TM₀₁ mode launcher is used as an RF coupler in Accelerator technology. Design of a compact circular waveguide TM₀₁ mode-launcher is presented in this paper. The design is based on the principle of magnetic field coupling between a wire loop and TM₀₁ mode of circular waveguide. The mode launcher exhibits high efficiency and 3.1% bandwidth at 3.2 GHz frequency with both circular and elliptical loop. Performance of the mode launcher is experimentally verified and simulated S-parameters agree with the measured results. The mode launcher is of compact size and is suitable for efficient excitation of TM₀₁ mode in circular waveguide and travelling wave structures. The launcher is also useful for cold testing of high power microwave antennas and Radars. M. Forno, "Design of a high power TM₀₁ mode launcher optimized for manufacturing by milling." 2016.
	Poster WEPAB349 [1.135 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB349
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 20 August 2021
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WEPAB400	Forced Coupling Resonance Driving Terms	dipole, optics, resonance, simulation	3646
	A. Wegscheider, R. Tomás García CERN, Meyrin, Switzerland
	At the LHC, coupling is routinely measured using forced oscillations of the beam through excitation with an AC-dipole. The driving of the particle motion has an impact on the measurement of resonance driving terms. Recent findings suggest that the current models describing the forced motion are neglecting a local effect of the AC-dipole, creating a jump of the amplitude of the resonance driving terms. This work presents a study of the improvement of coupling measurements for typical LHC optics as well as its upgrade project HL-LHC, by using the new model.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB400
About •	paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 20 August 2021
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THPAB001	Reaching the Sub Per Mil Level Coupling Corrections in the LHC	quadrupole, simulation, dipole, operation	3752
	E.J. Høydalsvik, T.H.B. Persson CERN, Geneva, Switzerland
	The High Luminosity LHC (HL-LHC) is requiring sub per mil coupling correction, as defined by the closest tune approach. In this article, the current coupling correction strategy is analyzed in order to understand if it can robustly correct to these very low levels. The impact of realistic errors on the coupling correction is investigated with MAD-X simulations, including the influence of local coupling on the global coupling correction. Through simulations and measurements in the LHC, the effect of BPM noise on the coupling correction is analyzed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB001
About •	paper received ※ 11 May 2021 paper accepted ※ 28 July 2021 issue date ※ 23 August 2021
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THPAB014	Matlab Simulations of the Helium Liquefier in the FREIA Laboratory	simulation, HOM, cavity, interface	3781
	E. Waagaard, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden
	We describe simulations that track a state vector with pressure, temperature, and gas flow through the helium liquefier in the FREIA laboratory. Most components, including three-way heat exchangers, are represented by matrices that allow us to track the state through the system. The only non-linear element is the Joule-Thomson valve, which is represented by a non-linear map for the state variables. Realistic properties for the enthalpy and other thermodynamic quantities are taken into account with the help of the Coolprop library. The resulting system of equations is rapidly solved by iteration and shows good agreement with the observed LHe yield with and without nitrogen pre-cooling.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB014
About •	paper received ※ 13 May 2021 paper accepted ※ 14 July 2021 issue date ※ 26 August 2021
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THPAB075	Collective (In)stability Near the Coupling Resonance	wakefield, resonance, simulation, impedance	3933
	R.R. Lindberg ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We show how to treat transverse collective instabilities when operating in the vicinity of the coupling (or tune difference) resonance. We begin by defining the approximate independent degrees of freedom including both linear coupling and chromatic effects. We then show how the destabilizing force due to wakefields and the stabilizing chromatic effects can be described by a linear combination of the horizontal and vertical motion that depends upon how close one is to the resonance. The theory agrees well with tracking studies, and will be relevant for those next-generation storage rings that plan to operate near the coupling resonance to produce nearly round beams, including the multi-bend achromat upgrade for the Advanced Photon Source.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB075
About •	paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 01 September 2021
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THPAB076	Effects of Chromaticity and Synchrotron Emission on Coupled-Bunch Transverse Stability	damping, simulation, synchrotron, wakefield	3937
	R.R. Lindberg ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We present a theory that can compute the transverse coupled-bunch instability growth rates at any chromaticity and for any longitudinal potential provided only that the long-range wakefield varies slowly over the bunch. The theory is expressed in terms of the usual coupled-bunch eigenvalues at zero chromaticity, and when the longitudinal motion is simple harmonic our solution only requires numerical root-finding that is easy to implement and fast to solve; the more general case requires some additional calculations but is still relatively fast. The theory predicts that the coupled-bunch growth rates can be significantly reduced when the chromatic betatron tune spread is larger than the coupled-bunch growth rate at zero chromaticity. Our theoretical results are compared favorably with tracking simulations for the long-range resistive wall instability, and we also indicate how damping and diffusion from synchrotron emission can further reduce or even stabilize the dynamics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB076
About •	paper received ※ 20 May 2021 paper accepted ※ 26 July 2021 issue date ※ 26 August 2021
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THPAB081	High-Power Prototype Canon Coupler for APS-U Booster Cavities	cavity, booster, GUI, injection	3956
	G.J. Waldschmidt, D.J. Bromberek, D. Horan, G. Trento, U. Wienands ANL, Lemont, Illinois, USA T. Harada, H. Oikawa, H. Takahashi CETD, Tochigi, Japan
	The Advanced Photon Source Upgrade (APS-U) plans to achieve a beam capture efficiency above 90% at 17 nC bunch charge into the Booster. Due to large beam loading at injection, the 352-MHz Booster cavities will be significantly detuned necessitating effective-power handling much greater than the 100kW effective power rating of the present coupler. Canon Electron Tubes & Devices Co., Ltd. (CETD) has designed and built a compact coupler for the APS-U Booster using a high-power ceramic disk window design in addition to accommodating significant space restrictions and additional diagnostics and cooling requirements. The coupler design was modified from an existing 500MHz, 800kW coupler that has been in routine operation at KEKB. The APS-U coupler has been installed and tested in the high-power 352-MHz test stand at the APS. The details of the design and testing of the prototype coupler will be reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB081
About •	paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 15 August 2021
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THPAB145	Cold Test of a Novel S-Band 1.6 Cell Photocathode RF Gun	gun, cavity, cathode, simulation	4045
	Zh.X. Tang, S.X. Dong, Y.J. Pei, B.F. Wei USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Funding: Work supported by National Natural Science Foundation of China(Grant No. 11805199 and U1832135) and Fundamental Research Funds for the Central Universities (Grant No. WK2310000072) The photocathode RF gun is one of the most critical components for high quality electron beam sources. The asymmetric multi-pole field contributes to the transverse emittance growth and degrades the beam quality. In order to overcome the problem, we propose a novel rotationally symmetric 1.6 cell RF gun to construct the symmetric field in this paper. The concrete proposal is that a coaxial cell cavity with a symmetrical distribution of four grooves is concatenated to the photocathode end of the traditional 0.6 cell cavity to form the novel 0.6 cell cavity. Through the detailed design study, the profile of the RF gun is optimized to improve the shunt impedance and mode separation and make the surface peak electric field at the photocathode end. Considering the filling time, a coupling slot is designed to couple input power into the RF gun. The RF cavity is machined by numerical control machine tool, and the tuning and low power RF measurement are carried out. The experimental results are consistent with the simulation results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB145
About •	paper received ※ 09 May 2021 paper accepted ※ 02 September 2021 issue date ※ 29 August 2021
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THPAB147	Preliminary Study of 500 MHz HOM-Free RF Cavity	cavity, HOM, GUI, damping	4050
	Zh.X. Tang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Funding: Work supported by National Natural Science Foundation of China(Grant No. U1832135 and 11805199)} In this paper, we study the microwave characteristics of 500 MHz RF cavity, including the optimization of cavity structure, the simulation design of high-order mode (HOM) absorption structure and the design of coupler. The cavity structure is simulated by CST. The absorption waveguide is designed and optimized. The coupler is designed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB147
About •	paper received ※ 09 May 2021 paper accepted ※ 16 July 2021 issue date ※ 02 September 2021
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THPAB167	Technical Design of an RFQ Injector for the IsoDAR Cyclotron	rfq, cyclotron, cavity, simulation	4075
	H. Höltermann, D. Koser, B. Koubek, H. Podlech, U. Ratzinger, M. Schuett, M. Syha BEVATECH, Frankfurt, Germany J.M. Conrad, J. Smolsky, L.H. Waites, D. Winklehner MIT, Cambridge, Massachusetts, USA
	For the IsoDAR (Isotope Decay-At-Rest) experiment, a high intensity (10 mA CW) primary proton beam is needed. To generate this beam, H²⁺ is accelerated in a cyclotron and stripped into protons after extraction. An RFQ, partially embedded in the cyclotron yoke, will be used to bunch and axially inject H²⁺ ions into the main accelerator. The strong RFQ bunching capabilities will be used to optimize the overall injection efficiency. To keep the setup compact the distance between the ion source and RFQ can be kept very short as well. In this paper, we describe the technical design of the RFQ. We focus on two critical aspects: 1. The use of a split-coaxial structure, necessitated by the low frequency of 32.8 MHz (matching the cyclotron RF) and the desired small tank diameter; 2. The high current, CW operation, requiring a good cooling concept for the RFQ tank and vanes.
	Poster THPAB167 [2.162 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB167
About •	paper received ※ 14 May 2021 paper accepted ※ 27 July 2021 issue date ※ 21 August 2021
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THPAB171	mm-Wave Linac Design for Next Generation VHEE Cancer Therapy Systems	linac, electron, simulation, impedance	4090
	E.J.C. Snively, K.C. Deering, E.A. Nanni SLAC, Menlo Park, California, USA

Paper

Title

Other Keywords

Page

MOPAB007

Prospect for Interaction Region Local Coupling Correction in the LHC Run 3

optics, quadrupole, luminosity, MMI

61

F. Soubelet, T.H.B. Persson, R. Tomás García
CERN, Geneva, Switzerland
O. Apsimon, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
O. Apsimon, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work was supported by STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) and CERN.
Successful operation of large scale particle accelerators depends on the precise correction of unavoidable magnet field or alignment errors present in the machine. In the LHC Run 2, local linear coupling in the Interaction Regions (IR) has been proven to have a severe impact on beam size and hence the luminosity - up to a 50% decrease -, making its handling a target for Run 3 and High Luminosity LHC (HL-LHC). However, current measurement methods are not optimised for local IR coupling. In this contribution, an approach to accurately minimise IR local coupling based on correlated external variables such as the |C-| is proposed. The validity of the method is demonstrated through simulations and benchmarked against theoretical values, such as Resonance Driving Terms (RDTs) and Ripken parameters.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB007

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paper received ※ 17 May 2021 paper accepted ※ 23 July 2021 issue date ※ 19 August 2021

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MOPAB019

Possible Application of Round-to-Flat Hadron Beam Creation Using 3rd Order Coupling Resonances for the Electron-Ion Collider

resonance, emittance, sextupole, electron

99

J. Kallestrup
PSI, Villigen PSI, Switzerland
X. Gu
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
An Electron-Ion Collider (EIC) is planned to be built in Brookhaven National Laboratory with the contribution from Jefferson National Laboratory. To have a high luminosity, both the EIC ion bunch and the EIC electron bunch are designed to be flat during their collision. The existing injector source provides a round beam of width 2.5 um rad transverse emittances. In this paper we investigate the option of dynamically crossing the 2Qx-Qy coupling resonance in order to create a flat-beam with emittance ratio Ex/Ey of up to 4. Furthermore, we explore the possibility of using a pulsed- or AC skew sextupole magnets to achieve a similar effect. Using one of these methods for flat beam creation will help lower the ion beam cooling time.

Poster MOPAB019 [0.323 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB019

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021

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MOPAB020

Improvements to the SLS Booster Synchrotron Performance Towards SLS 2.0

booster, emittance, sextupole, injection

103

J. Kallestrup, M. Aiba
PSI, Villigen PSI, Switzerland

The Swiss Light Source (SLS) storage ring will undergo a major upgrade to a multi-bend achromat lattice. The existing injector complex will be reused with few modifications. However, the SLS booster synchrotron has not been studied since the initial commissioning in years 2000-2001. We plan to apply an emittance exchange in the booster to lower the horizontal emittance, which is a critial parameter for the injection. Here, we present improvements to the SLS booster as a preparation for SLS 2.0 upgrade project. The vertical beam size is decreased by 50\% by the use of vertical orbit correctors without beam position monitors, leading also to suppression of vertical dispersion and a factor 10 reduction of the transverse coupling coefficient. The emittance exchange reflected these improvements in the horizontal emittance, achieving a factor of 9-10 reduction. Lastly, a fast head-tail instability limiting the injection rate into the storage ring is discovered and subsequently suppressed by correcting the chromaticities.

Poster MOPAB020 [0.380 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB020

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paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 30 August 2021

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MOPAB024

Efficient Coupling of Hydrodynamic and Energy-Deposition Codes for Hydrodynamic-Tunnelling Studies on High-Energy Particle Accelerators

simulation, target, proton, experiment

119

C. Wiesner, F. Carra, J. Kruse-Hansen, M. Masci, D. Wollmann
CERN, Meyrin, Switzerland
Y. Nie
KIT, Karlsruhe, Germany

The machine-protection evaluation of high-energy accelerators comprises the study of beyond-design failures, including the direct beam impact onto machine elements. In case of a direct impact, the nominal beam of the Large Hadron Collider (LHC) would penetrate more than 30 meters into a solid copper target. The penetration depth due to the time structure of the particle beam is, thus, significantly longer than predicted from purely static energy-deposition simulations with 7 TeV protons. This effect, known as hydrodynamic tunnelling, is caused by the beam-induced density depletion of the material at the target axis, which allows subsequent bunches to penetrate deeper into the target. Its proper simulation requires, therefore, to sequentially couple an energy-deposition code and a hydrodynamic code for the different target densities. This paper describes a method to efficiently couple the simulations codes Autodyn and FLUKA based on automatic density assignment and input file generation, and presents the results achieved for a sample case.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB024

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paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 28 August 2021

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MOPAB087

Design of a Multi-Bunch Feedback Kicker in SPEAR3

kicker, impedance, simulation, feedback

327

K. Tian, J.B. Langton, NL. Parry, J.A. Safranek, J.J. Sebek
SLAC, Menlo Park, California, USA

The new Multi-bunch feedback kickers have been designed to replace the current device loaned from ALS. In this paper, we first present the specification of the kickers based on the beam physics requirements. Then the mechanical design of the kicker is elaborated. Numerical simulations, both in time domain and in frequency domain, are conducted for evaluating the shunt impedance and beam coupling impedance of the kicker. Surface heating induced from the beam or the external source is estimated from the numerical results as well.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB087

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paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 01 September 2021

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MOPAB103

Study of Transverse Oscillation Coupling and Possibility of Its Minimization in SKIF (Novosibirsk)

quadrupole, emittance, sextupole, storage-ring

383

D. Leshenok
BINP, Novosibirsk, Russia
G.N. Baranov, E.B. Levichev, S.A. Nikitin
BINP SB RAS, Novosibirsk, Russia

The vertical emittance and, in general, the vertical beam size and angular divergence are of paramount importance in the SKIF (Russian acronym for Siberian Circular Photon Source) project developed in Novosibirsk. Therefore, a detailed simulation of the corresponding influence of possible errors in the storage ring was carried out with cross-validation by different methods. Variants of cross-coupling correction are proposed and modeled to obtain a vertical emittance of the order of one picometer simultaneously with minimizing vertical dispersion.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB103

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paper received ※ 18 May 2021 paper accepted ※ 17 August 2021 issue date ※ 19 August 2021

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MOPAB142

A Compact, Low-Field, Broadband Matching Section for Externally-Powered X-Band Dielectric-Loaded Accelerating Structures

vacuum, GUI, simulation, linac

495

Y. Wei, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
H. Bursali
Sapienza University of Rome, Rome, Italy
N. Catalán Lasheras, S. Gonzalez Anton, A. Grudiev, R. Wegner, Y. Wei
CERN, Meyrin, Switzerland
B.T. Freemire, C.-J. Jing
Euclid TechLabs, Solon, Ohio, USA
J. Sauza-Bedolla
Lancaster University, Lancaster, United Kingdom
Y. Wei, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

It has been technically challenging to efficiently couple external radiofrequency (RF) power to cylindrical dielectric-loaded accelerating (DLA) structures. This is especially true when the DLA structure has a high dielectric constant. This contribution presents a novel design of a matching section for coupling the RF power from a circular waveguide to an X-band DLA structure with a dielectric constant ε_r=16.66 and a loss tangent \tanθ = 3.43× 10^-5. It consists of a very compact dielectric disk with a width of 2.035 mm and a tilt angle of 60 degrees, resulting in a broadband coupling at a low RF field which has the potential to survive in the high-power environment. To prevent a sharp dielectric corner break, a 45-degree chamfer is added. Moreover, a microscale vacuum gap, caused by metallic clamping between the thin coating and the outer thick copper jacket, is studied in detail. Based on simulation studies, a prototype of the DLA structure with the matching sections was fabricated. Results from preliminary bench measurements and their comparison with design values will also be discussed.

Poster MOPAB142 [2.617 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB142

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paper received ※ 11 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021

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MOPAB155

Magnetic Breakdowns in Side-Coupled X-Band Accelerating Structures

impedance, simulation, cavity, accelerating-gradient

540

S.P. Antipov, P.V. Avrakhov, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
V.A. Dolgashev
SLAC, Menlo Park, California, USA
C. Jing
Euclid Beamlabs, Bolingbrook, USA

Funding: DOE SBIR
Side coupled accelerating structures are popular in the industrial realizations of linacs due to their high shunt impedance and ease of tuning. We designed and fabricated a side-coupled X-band accelerating structure that achieved 133 MOhm/m shut impedance. This structure was fabricated out of two halves using a novel brazeless approach. The two copper halves are joined together using a stainless steel joining piece with knife edges that bite into copper. This structure had been tested at high power at SLAC National Accelerator Laboratory. The performance of the structure had been limited by magnetic breakdowns on the side-coupling cells. In this paper we will present results of the high gradient tests and after-test analysis. Scanning electron microscopy images show a typical magnetic-field induced breakdown.

Poster MOPAB155 [1.069 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB155

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paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 01 September 2021

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MOPAB162

The First Trial of XY-Coupled Beam Phase Space Matching for Three-Dimensional Spiral Injection

injection, site, experiment, solenoid

553

M.A. Rehman, K. Furukawa, H. Hisamatsu, T. Mibe, H. Nakayama, S. Ohsawa, N. Saito, K. Sasaki
KEK, Ibaraki, Japan
H. Hirayama, H. Iinuma, K. Oda
Ibaraki University, Ibaraki, Japan
R. Matsushita
The University of Tokyo, Graduate School of Science, Tokyo, Japan
N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Funding: Work supported by "Grant in Aid" for Scientific Research, JSPS (KAKENHI# 26287055, KAKENHI#19H00673)
The most recent measurement of muon g-2 results in a 3.8σ discrepancy with the equally precise theoretical prediction. The J-PARC muon g-2/EDM experiment (E34) is in preparation to decipher this discrepancy and unravel the new physics beyond the standard model. The precision goal for g-2 is 0.1 ppm. To achieve this precision goal a novel 3-D spiral injection scheme has been devised to inject and store the beam into a small diameter MRI-type storage magnet for E34. The new injection scheme features smooth injection with high storage efficiency for the compact magnet. However, the spiral injection scheme is an unproven idea, therefore, a Spiral Injection Test Experiment (SITE) at KEK Tsukuba Campus is underway to establish this injection scheme. Due to the axial symmetric field of the solenoid magnet, a strongly XY-coupled beam is required. To produce the required phase space for the solenoid-type storage magnet, a beam transport line consisting of three rotatable quadrupole magnets has been designed and built for SITE. The vertical beam size reduction by means of phase space matching and other geometrical information has been successfully measured by the wire scanners.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB162

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paper received ※ 20 May 2021 paper accepted ※ 28 May 2021 issue date ※ 01 September 2021

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MOPAB180

AGS Dynamic Aperture at Injection of Polarized Protons and Helions

dynamic-aperture, proton, injection, extraction

610

K. Hock, H. Huang, F. Méot, N. Tsoupas
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Polarized helions are part of the physics program for the future EIC. An AC dipole has been installed in the AGS Booster to preserve polarization as helions are accelerated to |Ggamma|=10.5. Extraction from the AGS Booster at |Ggamma|=7.5 is possible but: would involve crossing an intrinsic resonance in the AGS, and would be the lowest rigidity beam injected into the AGS, and therefore experiences strong distortions of the optical functions because of the AGS two partial snakes. This lower rigidity would exacerbate the optical distortions from the snake, reducing the dynamic aperture. A comparison of the dynamic aperture of protons at Ggamma=4.5 to that of helions at |Ggamma|=7.5 and |Ggamma|=10.5 show that extraction at |Ggamma|=10.5 provides a larger dynamic aperture. This larger aperture would allow helions to be placed inside the spin tune gap generated by the two partial helices in AGS earlier in the cycle.

Poster MOPAB180 [0.453 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB180

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paper received ※ 17 May 2021 paper accepted ※ 31 May 2021 issue date ※ 20 August 2021

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MOPAB184

Unsupervised Learning Techniques for Tune Cleaning Measurement

ISOL, optics, luminosity, quadrupole

624

H. Garcia Morales
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
E. Fol, R. Tomás García
CERN, Meyrin, Switzerland

Precise measurements of tune and its stability are crucial for various optics analyses in the LHC, e.g. for the determination of the beta star using K-modulation. LHC BBQ system provides tune measurements online and stores the tune data. We apply unsupervised machine learning techniques on BBQ tune data in order to provide an automatic outlier detection method for better measurements of tune shifts and unexpected tune jitters.

Poster MOPAB184 [0.354 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB184

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paper received ※ 14 May 2021 paper accepted ※ 09 June 2021 issue date ※ 11 August 2021

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MOPAB187

Design and Calculation of the RF System of DC140 Cyclotron

cyclotron, cavity, simulation, resonance

636

A.S. Zabanov, V.B. Zarubin
JINR/FLNR, Moscow region, Russia
J. Franko, G.G. Gulbekyan, I.V. Kalagin, N.Yu. Kazarinov, S.V. Mitrofanov, V.A. Sokolov, K. Verlamov
JINR, Dubna, Moscow Region, Russia

Flerov Laboratory of Nuclear Reaction of Joint Institute for Nuclear Research carries out the works under creating of FLNR JINR Irradiation Facility based on the cyclotron DC140. The facility is intended for SEE testing of microchip, for production of track membranes and for solving of applied physics problems. The main systems of DC140 are based on the DC72 cyclotron ones that now are under reconstruction. The DC140 cyclotron is intended for acceleration of heavy ions with mass-to-charge ratio A/Z within interval from 5 to 5.5 up to two fixed energies 2.124 and 4.8 MeV per unit mass. The intensity of the accelerated ions will be about 1 pmcA for light ions (A<86) and about 0.1 pmcA for heavier ions (A>132). The designed RF-system of the DC-72 cyclotron with a half-wave cavity is not suitable due to the big vertical size. For this reason, a new quarter-wave RF-system was developed for the DC140 cyclotron project. The results of calculating the parameters of the new RF-system are given in this work.

Poster MOPAB187 [0.488 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB187

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paper received ※ 17 May 2021 paper accepted ※ 24 May 2021 issue date ※ 15 August 2021

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MOPAB195

Development of a Disk-and-Washer Cavity for the J-PARC Muon g-2/EDM Experiment

cavity, experiment, linac, quadrupole

658

Y. Takeuchi, J. Tojo
Kyushu University, Fukuoka, Japan
E. Cicek, K. Futatsukawa, N. Kawamura, T. Mibe, M. Otani, T. Yamazaki, M. Yoshida
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
R. Kitamura, Y. Kondo, T. Morishita
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Nakazawa
Ibaraki University, Hitachi, Ibaraki, Japan
N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Sue, K. Sumi, M. Yotsuzuka
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
H.Y. Yasuda
University of Tokyo, Tokyo, Japan

At J-PARC, an experiment using muons accelerated by a linac is planned to measure the anomalous magnetic moment of muons and to search for the electric dipole moment. A 1296 MHz disk and washer (DAW) coupled cavity linac (CCL) is being developed for use in the middle beta section of the muon linac. The DAW CCL consists of 14 tanks with 11 cells each. All tanks are connected by bridge couplers and electromagnetic quadrupole doublets for focusing are installed in each bridge coupler. The basic design of the DAW cavity has already been completed, and now detailed cavity design studies and manufacturing process studies are underway. In this poster, we will report about these studies and the preparation status of manufacturing the DAW cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB195

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paper received ※ 20 May 2021 paper accepted ※ 01 June 2021 issue date ※ 23 August 2021

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MOPAB211

Beam Coupling Impedances of Ferrite-Loaded Cavities: Calculations and Measurements

cavity, impedance, dipole, resonance

696

S.S. Kurennoy, R.C. McCrady
LANL, Los Alamos, New Mexico, USA

We have developed an efficient method of calculating impedances in cavities with dispersive ferrite dampers. The ferrite dispersive properties in the frequency range of interest are fitted in CST, which allows using both wakefield and lossy eigenmode solvers. A simple test cavity with or without ferrite inserts is explored both numerically and experimentally. The resonance frequencies and beam coupling impedances at cavity resonances are calculated with CST to understand the mode structure. The cavity transverse coupling impedances are also measured on a test stand using a two-wire method. We compare results of impedance calculations and measurements for a few different configurations, with and without ferrites, to ensure a complete understanding of the cavity resonances and their damping with ferrite. These results are important to provide adequate damping of undesired transverse modes in induction-linac cells.

Poster MOPAB211 [1.105 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB211

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paper received ※ 10 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021

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MOPAB215

Using ICA for Retrieving Teng Parameters

GUI, factory, optics, FEL

711

A. Lauterbach
IAP, Frankfurt am Main, Germany
G. Franchetti
GSI, Darmstadt, Germany

The blind source separation (BSS) method of Independent Component Analysis (ICA) is explored as a new approach for the reconstruction of the transfer matrix of Linear Coupling Parameterization. ICA is a method to detangle independent signals out of several measurements of their mixtures. In BSS-calculations, it is usually not possible to retrieve the mixing matrix, for the source signals, as well as the matrix, are unknown. Combining the parameterization model of D.A. Edwards and L.C. Teng with the standard ICA approach, it is though possible to retrieve the mixing matrix, as the form of the original uncoupled motion is known. At the same time arises the possibility to recalculate the parameters of Edwards and Teng through a system of equations of the one turn map components. It can be shown as a proof of concept, that the parameters can be reconstructed up to high accuracy for a simulated, non-perturbed signal.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB215

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paper received ※ 10 May 2021 paper accepted ※ 31 May 2021 issue date ※ 23 August 2021

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MOPAB226

Analytical Description of the Steerer Parameters in the Bilinear-Exponential Model at DELTA

betatron, storage-ring, closed-orbit, simulation

737

S. Kötter
DELTA, Dortmund, Germany

At DELTA, a 1.5 GeV synchrotron radiation source operated by the TU Dortmund University, an analytical description of the steerer parameters in the bilinear-exponential (BE) model has been developed. The BE model describes the coupled orbit response in a storage ring. It is used in the closed-orbit bilinear-exponential analysis (COBEA) algorithm to decompose orbit response matrices into beta function, betatron phase, and a scaled dispersion. After introducing the BE model and the analytical steerer parameters, a simulation-based comparison of the BE model and another coupled orbit response model is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB226

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paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 11 August 2021

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MOPAB260

Optics Corrections with LOCO on Sirius Storage Ring

quadrupole, optics, storage-ring, MMI

825

M.B. Alves
LNLS, Campinas, Brazil

Sirius is a 4th generation 3GeV synchrotron light source at the Brazilian Center for Research in Energy and Materials (CNPEM). In this work, we report the results of linear optics and coupling corrections during the commissioning of Sirius storage ring, using the Linear Optics from Closed Orbits (LOCO) algorithm. Beam-based measurements were performed to verify independently the impact of corrections on storage ring parameters.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB260

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 30 August 2021

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MOPAB273

Nonlinear Coupling Resonances in X-Y Coupled Betatron Oscillations Near the Main Coupling Resonance in VEPP-2000 Collider

resonance, betatron, collider, experiment

863

S.A. Kladov, E. Perevedentsev
BINP SB RAS, Novosibirsk, Russia
S.A. Kladov, E. Perevedentsev
NSU, Novosibirsk, Russia

In the vicinity of the linear coupling resonance where the working point of the collider is positioned, we study the effect of nonlinear coupling resonances on the single-particle phase space, beam sizes and the waveform of coherent beam motion. The latter is interesting for diagnostics of the nonlinear dynamics.

Poster MOPAB273 [1.142 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB273

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paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 21 August 2021

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MOPAB274

Two-Stream Effects in Coherent Beam-Beam Oscillations in VEPP-2000 Collider Near the Linear Coupling Resonance

betatron, collider, synchrotron, resonance

866

S.A. Kladov, E. Perevedentsev
BINP SB RAS, Novosibirsk, Russia
S.A. Kladov, E. Perevedentsev
NSU, Novosibirsk, Russia

Synchro-betatron motion of colliding bunches may cause limitations of the high-luminosity performance. For a round beam collider operated near the linear coupling resonance, we present theoretical predictions of the beam-beam coherent synchro-betatron oscillation behavior under the influence of x-y coupling.

Poster MOPAB274 [0.968 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB274

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 02 September 2021

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MOPAB291

Design of Cavity BPM Pickup for EuPRAXIA@SPARC_LAB

cavity, GUI, pick-up, simulation

924

Sh. Bilanishvili
INFN/LNF, Frascati (Roma), Italy

EuPRAXIA@SPARC_LAB will make available at LNF a unique combination offering three different options. A high-brightness electron beam with 1 GeV energy generated in a novel X-band RF linac; A PW-class laser system, and a compact light-source directly driven by a plasma accelerator*. Plasma and conventional RF linac driven FEL provide beam with parameters of 30- 200pC charge range, 10-100Hz repetition rate, and 1 GeV electron energy**. The control of the charge and the trajectory monitoring at a few pC and a few um is mandatory in this machine. Particularly in the plasma interaction region, where the pickup resolution under 1 um is required. As a possible solution, a cavity beam position monitor (cBPM) is proposed. A prototype in the C-band frequency range has been designed. The pickup was optimized for low charge and single-shot bunches. The poster presents the process to achieve the required specifications. The simulations were performed to study RF properties and the electromagnetic response of the device. Finally, the overall performance of the pickup is discussed, and theoretical resolution is approximated.
* https://www.researchgate.net/publication/335459394_From_SPARC_LAB_to_EuPRAXIASPARC_LAB
**http://www.lnf.infn.it/sis/preprint/detail-new.php?id=5416

Poster MOPAB291 [16.718 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB291

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 23 August 2021

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MOPAB326

Maximum Entropy Reconstruction of 4D Transverse Phase Space from 2D Projections: with Application to Laser Wire Measurements in the SNS HEBT

laser, emittance, neutron, linac

1008

C.Y. Wong, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

We employ the principle of maximum entropy (MENT) to reconstruct 4D transverse phase space from its 2D projections. Emittance devices commonly measure two specific 2D projections, i.e. the horizontal and vertical phase space distributions. We show that: 1) given only these two 2D projections, their product is the analytic MENT solution to the 4D distribution; and 2) additional 2D projections provide information on inter-plane coupling in the MENT reconstruction of the 4D phase space which can be solved numerically. At the Spallation Neutron Source (SNS), laser wires in the high energy beam transport (HEBT) enable non-invasive two-slit type transverse phase space measurements. Laser wires play the role of the first slit whereas physical wires downstream of a drift act as the second slit. We reconstruct the 4D phase space in the HEBT using all four horizontal/vertical permutations of the two slits where: 1) the two configurations with parallel slits constitute ordinary 2D phase space measurements in either plane; and 2) the two configurations with perpendicular slits carry coupling information.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB326

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paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 17 August 2021

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MOPAB329

Operations of Copper Cavities at Cryogenic Temperatures

cavity, linac, cryogenics, ECR

1020

H. Wang, U. Ratzinger, M. Schuett
IAP, Frankfurt am Main, Germany

How the anomalous skin effect by copper affects the efficiency of copper- cavities will be studied in the experiment, especially at lower temperatures. The accurate quality factor Q and resonant frequency of three coaxial cavities will be measured over the temperature range from 300 to 22 K. The three coaxial cavities have the same structure, but different lengths, which correspond to resonant frequencies: around 100 MHz, 220 MHz and 340 MHz. The motivation is to check the feasibility of an efficient pulsed, liquid nitrogen cooled ion linac.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB329

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paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 02 September 2021

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MOPAB330

Production and Performance Evaluation of a Compact Deflecting Cavity to Measure the Bunch Length in the cERL

cavity, resonance, vacuum, impedance

1023

D. Naito, Y. Honda, T. Miyajima, N. Yamamoto
KEK, Ibaraki, Japan

At the KEK compact energy recovery linac, we try to generate an infrared free-electron laser (FEL). To generate the FEL, an electron bunch should be compressed along the longitudinal direction. The measurement of the bunch length is key to optimize the bunch compression. We plan to measure the bunch length by deflecting cavities in the burst mode. The deflecting cavities are required to be a time resolution of 33 fs in order to not only measure the bunch length but also resolve the structure inside the electron bunch. To achieve the requirement, we developed a c-band cavity whose RF input port is compact. The deflecting cavity is a single cell and normal conducting cavity. The deflection mode of the cavity is TM110. The 12 cavities will be located at the exit of undulators. In this presentation, we explain the design of our cavity and report the production of the first cavity. We also report the evaluation of the resonance frequency, the unloaded Q and the external Q of the cavity. From the measurements and simulations, the R/Q is estimated to be 1 mega orms. The time resolution of the cavity is expected to be 400 fs when the input RF power is 1 kW and the beam energy is 20 MeV.

Poster MOPAB330 [12.920 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB330

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paper received ※ 12 May 2021 paper accepted ※ 08 June 2021 issue date ※ 28 August 2021

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MOPAB331

Design Consideration of a Longitudinal Kicker Cavity for Compensating Transient Beam Loading Effect in Synchrotron Light Sources

cavity, kicker, resonance, impedance

1027

D. Naito, S. Sakanaka, T. Takahashi, N. Yamamoto
KEK, Ibaraki, Japan
T. Yamaguchi
Sokendai, Ibaraki, Japan

In ultra-low-emittance synchrotron light sources, bunch-lengthening using the combination of main and harmonic cavities is limited by the transient beam-loading (TBL) effect which is caused by gaps in the fill pattern. To manage this effect, we proposed a TBL compensation technique using a wide-band longitudinal kicker cavity*. In the future KEK-LS storage ring, for example, the kicker cavity should provide a compensation voltage of 50 kV with a -3dB bandwidth (BW) of about 5 MHz, as well as its higher-order modes (HOM) should be damped sufficiently. In this presentation, we report our conceptual design of the kicker cavity. We employed the single-mode (SM) cavity concept so that harmful HOMs are dumped by rf absorbers on the beam pipes. The distinctive feature of the SM cavity is its simple structure since it has no HOM damper on the cavity. Another feature is its low R/Q by which the TBL effect in the kicker cavity itself can be reduced significantly. We employed a frequency of 1.5 GHz (third-harmonic) and R/Q of 60 orms through optimizations. Using this kicker cavity with a double rf system, a bunch lengthening by a factor of 4.3 (i.e., 40.9 ps) is expected for the KEK-LS case.
* N.Yamamoto et al., Phys. Rrev. Acc. Beams 21, 012001 (2018)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB331

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paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 01 September 2021

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MOPAB332

Design of 4th Harmonic RF Cavities for ESRF-EBS

HOM, cavity, SRF, impedance

1031

A. D’Elia, J. Jacob, V. Serrière, X.W. Zhu
ESRF, Grenoble, France

Funding: European Union’s Horizon 2020 research and innovation program under grant #871072
An active 4th harmonic RF system for bunch lengthening is under study at the ESRF to improve the performance of the new EBS storage ring, mainly for few bunch operation with high currents per bunch, by reducing Touschek and intrabeam scattering, thereby increasing the lifetime and limiting the emittance growth. It will also reduce impedance heating of the vacuum chambers. The 4th Harmonic 1.41 GHz normal conducting cavity design takes inspiration from the KEK idea of using a TM020 mode exhibiting a reduced R/Q but a higher unloaded Q with respect to TM010. We propose to use multicell cavities for their compactness, the reduced number of required ancillaries and the ease of control for a reduced number of cavities. The drawback is the complexity of the model and the necessity to damp the lower order TM010 mode (LOM) as well as the higher order modes (HOM). The RF design of a 4th harmonic multicell damped cavity will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB332

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paper received ※ 19 May 2021 paper accepted ※ 17 August 2021 issue date ※ 16 August 2021

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MOPAB339

Design Of An X-band 3MeV Standing-wave Accelerating Structure with Nose-cone Structure Made From Two Halves

impedance, cavity, electron, bunching

1051

F. Liu, H.B. Chen, J. Shi, C.-X. Tang, H. Zha
TUB, Beijing, People’s Republic of China

This work presents an X-band 3MeV standing-wave accelerating structure with nose cones made from two halves. Milling two longitudinally split halves is one economic method to manufacture accelerating structure for decrease of welding, with increasing the difficulty in machining. This linear accelerator includes 4 buncher cavities and 4 accelerating cavities, and nose cone is applied to achieve high shunt impedance. A technical prototype is under fabrication to bring two milled halves manufacture way into practical application.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB339

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paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 15 August 2021

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MOPAB343

Optimization of the Parasitic-Mode Damping on the 1.5 GHz TM020-type Harmonic Cavity

cavity, damping, impedance, simulation

1064

T. Yamaguchi
Sokendai, Ibaraki, Japan
D. Naito, S. Sakanaka, T. Takahashi, N. Yamamoto
KEK, Ibaraki, Japan

Bunch-lengthening harmonic cavity is one of the essential tools to mitigate the intrabeam scattering in the 4th-generation synchrotron light sources. For this purpose, we proposed a normal-conducting 1.5 GHz harmonic cavity* of TM020-type**. Thanks to its low R/Q (68 ohms) and high unloaded Q (34, 000), bunch gap transient in the harmonic cavity can be reduced to ~20% as compared to that in a typical TM010 cavity. Furthermore, harmful parasitic modes in this cavity can be heavily damped by installing ferrites where no magnetic fields of TM020-mode exist. However, some of the parasitic modes, e.g. TM021 and TM120 modes, are difficult to damp because their field patterns are similar to that of the TM020 mode. To damp such modes effectively, we optimized the cavity inner shape by tailoring the curvature at the cavity equator, the shape of the nose cones, and introducing "bumps" on the inner wall. Our goals of the coupling impedances are fxR < 2.4[kohm GHz] and RT < 23 kohm/m in the longitudinal and the transverse planes, respectively. As a result of optimization, we almost achieved these goals. To confirm our simulation results, fabrication of a low-power test cavity is in progress.
* N . Yamamoto et al., Phys. Rev. Acc. Beams 21, 012001 (2018).
** H. Ego et al., Proc. of the 11th Annual Meeting of Particle Accelerator Society of Japan (PASJ2014), MOOL14 (2014).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB343

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paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 01 September 2021

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MOPAB353

Design of a compact Ka-Band Mode Launcher for High-gradient Accelerators

cavity, simulation, quadrupole, accelerating-gradient

1100

G. Torrisi, G.S. Mauro, G. Sorbello
INFN/LNS, Catania, Italy
M. Behtouei, L. Faillace, B. Spataro, A. Variola
INFN/LNF, Frascati, Italy
V.A. Dolgashev
SLAC, Menlo Park, California, USA
L. Faillace, M. Migliorati
Sapienza University of Rome, Rome, Italy
M. Migliorati
INFN-Roma1, Rome, Italy
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
G. Sorbello
University of Catania, Catania, Italy

In this work, we present the RF design of a table-top Ka-Band mode launcher operating at 35.98 GHz. The structure consists of a symmetrical 4-port WR28 rectangular-TE10-to-circular-TM01 mode converter that is used to couple a peak output RF power of 5 MW (pulse length up to 50 ns and repetition rate up to 100 Hz) in Ka-Band linear accelerator able to achieve very high accelerating gradients (up to 200 MV/m). Numerical simulations have been carried out with the 3D full-wave commercial simulator Ansys HFSS in order to obtain a preliminary tuning of the accelerating field flatness at the operating frequency f0=35.98 GHz. The main RF parameters, such as reflection coefficient, transmission losses, and conversion efficiency are given together with a verification of the field azimuthal symmetry which avoids dipole and quadrupole deflecting modes. To simplify future manufacturing, reduce fabrication costs, and also reduce the probability of RF breakdown, the proposed new geometry has "open" configuration. This geometry eliminates the flow of RF currents through critical joints and allows this device to be milled from metal blocks.

Poster MOPAB353 [3.131 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB353

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 27 August 2021

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MOPAB362

Atomistic Modeling of the Coupling Between Electric Fields and Bulk Plastic Deformation in Rf Structures

simulation, experiment, feedback, framework

1125

S. Bagchi, D. Perez
LANL, Los Alamos, New Mexico, USA

Funding: LANL-LDRD
A notable bottleneck in achieving high-gradient RF technology is dictated by the onset of RF breakdown. While bulk mechanical properties are known to significantly affect breakdown propensity, the underlying mechanisms coupling RF fields to bulk plastic deformation in experimentally relevant thermo-electrical loading conditions remain to be identified at the atomic scale. Here, we present results of large-scale molecular dynamics simulations (MD) to investigate possible modes of coupling. We consider the activation of Frank-Read (FR) sources, which leads to dislocation multiplication, under the action of bi-axial thermal stresses and surface electric-field. With a charge-equilibration formalism incorporated in a classical MD model, we show that a surface electric field acting on an either preexisting or dislocation-induced surface step, can generate a long-range resolved shear stress field inside the bulk of the sample. We investigate the feedback between step growth following dislocation emission and subsequent activations of FR sources and discuss the regimes of critical length-scales and densities of dislocations, where such a mechanism could promote RF breakdown precursors.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB362

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paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 19 August 2021

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MOPAB364

Shielded Pair Method for Cylindrical Surface Resistance Measurement at Cryogenic Temperature

factory, cryogenics, dipole, simulation

1132

K. Brunner, S. Calatroni, F. Caspers
CERN, Geneva, Switzerland
D. Barna
Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary

The shielded pair resonator method was already used in the past at CERN to measure the surface resistivity of the LHC beam screen both at room temperature and cryogenic temperature. We have refined and adapted the measurement to be able to measure other types of beam screens and also to operate in a strong dipolar magnetic field. This is necessary for testing the properties of HTS coated beam screens or the possible effects of coatings and surface treatments for e-cloud suppression. Several calibration runs were done at cryogenic temperatures (4.2 K) measuring the surface resistivity of a copper pipe to identify the precision, stability and reproducibility achievable using this method. This work describes the challenges of the measurement and ways to mitigate them.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB364

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paper received ※ 17 May 2021 paper accepted ※ 22 June 2021 issue date ※ 12 August 2021

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MOPAB371

A Coupon Tester for Normal Conducting High-Gradient Materials

cavity, vacuum, RF-structure, klystron

1147

J.W. Lewellen, D. Gorelov, D. Perez, E.I. Simakov
LANL, Los Alamos, New Mexico, USA
M.E. Schneider
Michigan State University, East Lansing, Michigan, USA

Funding: Los Alamos National Laboratory LDRD Program
A coupon tester is an RF structure used to subject a material sample to very high RF fields, with the fields on the sample, or coupon, being higher than elsewhere in the cavity. To date, most such cavities were originally intended to explore the RF properties of superconducting materials, and can expose the sample to strong magnetic fields, but weak to no electric fields. As part of a program to develop materials and structures for high-gradient (> 100 MV/m), low-breakdown-rate normal-conducting accelerators, we have designed a C-band (5.712 GHz) cavity intended to subject samples to both magnetic and electric fields comparable to those experienced in high-gradient structure designs, using a TM-mode cavity; the electric and magnetic fields along the sample coupon can be directly compared to the fields on the iris of high-gradient structures. This poster will present the design criteria for our coupon tester cavity, nominal operating parameters, and our structure concept. The cavity design will be refined over the next several months, and will be constructed and in service near the start of 2022.

Poster MOPAB371 [0.764 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB371

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paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 30 August 2021

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TUPAB006

The Impact of Beam Position Monitor Tilts on Coupling Measurements

resonance, optics, simulation, quadrupole

1342

L. van Riesen-Haupt, R. Tomás García
CERN, Meyrin, Switzerland

The measurement and correction of coupling resonance driving terms is a key tool for improving the performance of synchrotrons. These terms are measured by exciting the beam and observing the subsequent motion in the horizontal and vertical planes through beam position monitors. This paper outlines the impact of tilt errors in these monitors to the distortion of the amount of coupling measured between the planes and how the computation of the resonance driving terms is affected by these tilts. It also attempts to use these results for mimicking tilt errors in simulations and discusses how discrepancies in measured resonance driving terms could be used to estimate the tilt errors that cause them.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB006

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paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 12 August 2021

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TUPAB016

ESS RFQ: Installation and Tuning at Lund

rfq, quadrupole, insertion, cavity

1372

P. Hamel, D. Chirpaz-Cerbat, M. Desmons, A.C. France, O. Piquet
CEA-IRFU, Gif-sur-Yvette, France
A. Dubois, Y. Le Noa
CEA-DRF-IRFU, France

The 352 MHz Radio Frequency Quadrupole (RFQ) for the European Spallation Source ERIC (ESS) has been delivered by the end of 2019. It has been provided by CEA, IRFU, Saclay/France. It consists of five sections with a total length of 4.6 m and accelerates the 70 mA proton beam from 75 keV up to 3.6 MeV. It will be fed with 900 kW peak power through two coaxial loop couplers. The installation process (alignment, vacuum test), as well as the tuning process based on bead-pull measurements, is presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB016

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paper received ※ 18 May 2021 paper accepted ※ 06 July 2021 issue date ※ 14 August 2021

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TUPAB041

Detector Solenoid Compensation for the Electron-Ion Collider

solenoid, electron, detector, cavity

1439

B.R. Gamage, T.J. Michalski, V.S. Morozov, R. Rajput-Ghoshal, A. Seryi, W. Wittmer, Y. Zhang
JLab, Newport News, Virginia, USA
E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA
A. Kiselev, H. Lovelace III, B. Parker, S. Peggs, S. Tepikian, F.J. Willeke, H. Witte, Q. Wu
BNL, Upton, New York, USA

Funding: Jefferson Science Associates, LLC Contract No. DE-AC05-06OR23177, Fermi Research Alliance, LLC Contract No. DE-AC02-07CH11359, and Brookhaven Science Associates, LLC Contract No. DE-SC0012704
The central detector in the present EIC design includes a 4 m long solenoid with an integrated strength of up to 12 Tm. The electron beam passes on-axis through the solenoid, but the hadron beam has an angle of 25 mrad. Thus the solenoid couples horizontal and vertical betatron motion in both electron and hadron storage rings, and causes a vertical closed orbit excursion in the hadron ring. The solenoid also couples the transverse and longitudinal motions of both beams, when crab cavities are also considered. In this paper, we present schemes for closed orbit correction and coupling compensation at the IP, including crabbing.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB041

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paper received ※ 28 May 2021 paper accepted ※ 31 August 2021 issue date ※ 12 August 2021

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TUPAB051

Elettra and Elettra 2.0

emittance, insertion, insertion-device, status

1474

E. Karantzoulis, A. Carniel, D. Castronovo, S. Di Mitri, B. Diviacco, S. Krecic
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with the future upgrade concerning the new ultra-low emittance light source Elettra 2.0 that will provide ultra-high brilliance while the very short pulses feasibility study for time resolved experiments is in progress.

Poster TUPAB051 [1.632 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB051

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paper received ※ 10 May 2021 paper accepted ※ 27 May 2021 issue date ※ 20 August 2021

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TUPAB054

CDR BASELINE LATTICE FOR THE UPGRADE OF SOLEIL

lattice, emittance, injection, photon

1485

A. Loulergue, D. Amorim, P. Brunelle, A. Gamelin, A. Nadji, L.S. Nadolski, R. Nagaoka, R. Ollier, M.-A. Tordeux
SOLEIL, Gif-sur-Yvette, France

Previous MBA studies converged toward a lattice composed of 20 7BA solution elaborated by adopting the sextupole pairing scheme with dispersion bumps originally developed at the ESRF-EBS. It provided a low natural horizontal emittance value of 70-80 pm-rad range at an energy of 2.75 GeV. Due to difficulties to accommodate such lattice geometry in the SOLEIL present tunnel as well as to preserve at best the beamline positioning, alternative lattice based on HOA (Higher-Order Achromat) type cell has been recently investigated. The HOA type cell being more modular and possibly exhibiting larger momentum acceptance as well as low emittances, a solution alternating 7BA and 4BA cells was then identified as the best to adapt the current beamline positioning. The SOLEIL CDR upgrade reference lattice is then composed of 20 HOA cells alternating 7BA and 4BA giving a natural horizontal emittance of 80 pm-rad. The linear and non-linear beam dynamic properties of the lattice along with the possibility of horizontal off-axis injection at full betatron coupling are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB054

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paper received ※ 21 May 2021 paper accepted ※ 02 July 2021 issue date ※ 10 August 2021

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TUPAB077

Novel Open Cavity for Rotating Mode SLED-Type RF Pulse Compressors

cavity, klystron, GUI, linear-collider

1547

X.W. Wu, A. Grudiev
CERN, Meyrin, Switzerland

A new X-band high-power rotating mode SLAC Energy Doubler (SLED)-type rf pulse compressor is proposed. It is based on a novel cavity type, a single open bowl-shape energy storage cavity with high Q₀ and compact size, which is coupled to the waveguide using a compact rotating mode launcher. The novel cavity type is applied to the rf pulse compression system of the main linac rf module of the klystron-based option of the Compact Linear Collider (CLIC). Quasi-spherical rotating modes of \rm{TE}_1,2,4 and \rm{TE}_1,2,13 are proposed for the correction cavity and storage cavity of the rf pulse compression system respectively. The storage cavity working at \rm{TE}_1,2,13 has a Q₀ of 240000 and a diameter less than 33 cm. The design of the pulse compressor and in particular of the high-Q cavity will be presented in detail.

Poster TUPAB077 [1.229 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB077

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paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 27 August 2021

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TUPAB133

Brazing free RF Pulse Compressor for High Gradient Accelerators

GUI, cavity, simulation, vacuum

1700

L. Kankadze, D. Alesini, F. Cardelli, G. Di Raddo, M. Diomede
INFN/LNF, Frascati, Italy

EURPRAXIA@SPARC\_LAB, is a proposal to upgrade the SPARC\_LAB test facility (at LNF, Frascati) to a soft X-ray user facility based on plasma acceleration and high-gradient X-band (11.9942 GHz) accelerating modules. Each module is made up of a group of 4 TW sections assembled on a single girder and fed by one klystron by means of one rf pulse compressor system and a low attenuation circular waveguide network that transports the rf power to the input hybrids of the sections. The pulse compressor is based on a single Barrel Open Cavity (BOC). The BOC use a ’whispering gallery’ mode which has an intrinsically high quality factor and operates in a resonant rotating wave regime. Compared to the conventional SLED scheme it requires a single cavity instead of two cavities and a 3-dB hybrid. A new brazeless mechanical design has been proposed and is described in the present paper together with the electro-magnetic and thermo-mechanical simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB133

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paper received ※ 21 May 2021 paper accepted ※ 15 June 2021 issue date ※ 10 August 2021

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TUPAB170

Decouple Transverse Coupled Beam in the DTL with Tilted PMQs

emittance, DTL, rfq, cavity

1785

P.F. Ma, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng
TUB, Beijing, People’s Republic of China
Y.H. Pu, J. Qiao, C.P. Wang, X.C. Xie, F. Yang
Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China

The coupling of the beam is widely studied in the accelerator physics field. Projected transverse emittances easily grow up if the beam is transversely-coupled. If we decouple the transverse coupled beam, the transverse emittance can be small. The matrix approach based on the symplectic transformation theory for decoupling the coupled beam is summarized. For a proton accelerator, the transverse coupled beam is introduced by an RFQ tilted by 45°. The beam is decoupled with the first five tilted quadrupoles mounted in the DTL section. A study on the gradient choice of the quadrupoles and the space charge effect is given in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB170

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paper received ※ 08 May 2021 paper accepted ※ 21 June 2021 issue date ※ 28 August 2021

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TUPAB171

Linear Transfer Matrix of a Half Solenoid

solenoid, emittance, optics, ion-source

1789

P.F. Ma, X. Guan, X.W. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng
TUB, Beijing, People’s Republic of China

Solenoid magnets can provide strong transverse focusing to electrons and ions with relatively small energies. For the ECR heavy-ion source, the ions are extracted at the central area of the solenoid, the beam is coupled at the exit of the source. The coupling caused by the solenoids can lead to the growth of projected transverse emittance, which has been widely studied with great interest. It is important to study the transfer matrix of a half solenoid to study the beam optics in an ECR souce, thus the property of the beam can be given. Based on the transfer matrix calculation, the summary of the linear transfer matrix of a half solenoid can be given. The beam optics in a half solenoid is studied.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB171

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paper received ※ 18 May 2021 paper accepted ※ 28 June 2021 issue date ※ 29 August 2021

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TUPAB232

Linear Coupling and Adiabaticity of Emittance Exchange

resonance, emittance, extraction, proton

1972

F. Capoani, M. Giovannozzi
CERN, Geneva, Switzerland
A. Bazzani, F. Capoani
Bologna University, Bologna, Italy
A.I. Neishtadt
IKI, Moscow, Russia
A.I. Neishtadt
Loughborough University, Leicestershre, United Kingdom

In circular accelerators, crossing the coupling resonance induces the exchange of the transverse emittances, provided the process is adiabatic. In this paper, we introduce a theoretical framework to analyze the resonance-crossing process, based on Hamiltonian mechanics, which is capable of explaining all the features of the emittance exchange process.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB232

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paper received ※ 11 May 2021 paper accepted ※ 16 June 2021 issue date ※ 27 August 2021

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TUPAB242

The Beam-Study of the Side and On-Axis RF Cavities in S-Band 6 MeV LINACs

cavity, target, emittance, impedance

2008

A. Khosravi, B. Shokri
LAPRI, Tehran, Iran
N. Khosravi
ILSF, Tehran, Iran

The geometry of side and on-axis RF cavities are two magnetic-coupled designs for the different LINAC applications. The electromagnetic fields, RF power, beam parameters, thermal stability, and manufacturing costs are the most critical factors in cavity type selection in each application. In this article, both RF-cavities are optimized in POISSON SUPERFISH code to compare the beam parameters accurately. Then the optimized cavities are making a tube and compare in ASTRA 1D code and CST 3D software. At last, the thermal sensitivity of both models is studied in MPHYSICS module of the CST. As a result, the final decision can be achieved on the side or on-axis cavities considering the input power, costs, beam properties, and thermal stability for the different applications of the LINACs

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB242

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paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021

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TUPAB258

Impact of Coherent Beam-Beam Interaction on the Landau Damping of the Transverse Coupled-Bunch Instability

dipole, electron, damping, proton

2062

R. Li
JLab, Newport News, Virginia, USA
M. Blaskiewicz
BNL, Upton, New York, USA

Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
In the EIC design, at high average-current operation, the transverse coupled-bunch instability (TCBI) induced by the long-range transverse resistive-wall wakefield in the electron storage ring (eSR) has a fast growth rate and requires efficient mitigation. A natural mitigation mechanism is provided by the beam-beam interaction at the interaction point (IP), which gives a strong Landau damping for the TCBI in the eSR. In this study, using a simplified simulation model, we investigate how this Landau damping from the beam-beam interaction behaves when the coherent beam-beam interaction at IP is considered. Our method and results will be presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB258

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paper received ※ 21 June 2021 paper accepted ※ 01 July 2021 issue date ※ 25 August 2021

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WEPAB026

Optics Measurements and Correction Plans for the HL-LHC

optics, luminosity, dynamic-aperture, dipole

2656

T.H.B. Persson, X. Buffat, F.S. Carlier, R. De Maria, J. Dilly, E. Fol, D. Gamba, H. Garcia Morales, A. García-Tabarés Valdivieso, M. Giovannozzi, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, P.K. Skowroński, F. Soubelet, R. Tomás García, F.F. Van der Veken, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt
CERN, Geneva, Switzerland
J.M. Coello de Portugal
PSI, Villigen PSI, Switzerland

The High Luminosity LHC (HL-LHC) will require stringent optics correction to operate safely and deliver the design luminosity to the experiments. In order to achieve this, several new methods for optics correction have been developed. In this article, we outline some of these methods and we describe the envisioned strategy of how to use them in order to reach the challenging requirements of the HL-LHC physics program.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB026

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paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 30 August 2021

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WEPAB027

Optics Correction Strategy for Run 3 of the LHC

optics, dipole, MMI, quadrupole

2660

T.H.B. Persson, R. De Maria, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, F. Soubelet, R. Tomás García, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt
CERN, Geneva, Switzerland
J.F. Cardona
UNAL, Bogota D.C, Colombia

The Run 3 of the LHC will continue to provide new challenges for optics corrections. In order to succeed and go beyond what was achieved previously, several new methods to measure and correct the optics have been developed. In this article we describe these methods and outline the plans for the optics commissioning in 2022.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB027

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paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021

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WEPAB148

RF Design of an X-Band TM02 Mode Cavity for Field Emitter Testing

cavity, electron, insertion, multipactoring

2961

Z. Li, S.G. Tantawi
SLAC, Menlo Park, California, USA
S.V. Baryshev, T. Posos, M.E. Schneider
Michigan State University, East Lansing, Michigan, USA

Funding: Work at SLAC was supported by DOE under contract No. DE-AC02-76SF00515. Work at MSU was supported by DOE under Award No. DE-SC0020429 and under Cooperative Agreement Award No. DE-SC0018362.
Planar polycrystalline synthetic diamond with nitrogen-doping/incorporation was found to be a remarkable field emitter. It is capable of generating a high charge beam and handling moderate vacuum conditions. Integrating it with an efficient RF cavity could therefore provide a compact electron source for RF injectors. Understanding the performance metrics of the emitter in RF fields is essential toward developing such a device. We investigated a test setup of the field emitter at the X-band frequency. The setup included an X-band cavity operating at the TM02 mode. The field emitter material will be plated on the tip of a insertion rod on the cavity back plate. Part of the back plate and the emitter rod are demountable, allowing for exchange of the field emitters. The TM02 mode was chosen such that the design of the demountable back plate does not induce field enhancement at the installation gap. The cavity were optimized to achieve a high surface field at the emitter tip and a maximum energy gain of the emitted electrons at a given input power. We will present the RF and mechanical design of such a TM02 X-band cavity for field emitter testing.

Poster WEPAB148 [1.642 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB148

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paper received ※ 14 May 2021 paper accepted ※ 12 July 2021 issue date ※ 12 August 2021

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WEPAB164

Electrodeless Diamond Beam Halo Monitor

electron, experiment, radiation, vacuum

2990

S.V. Kuzikov, S.P. Antipov, P.V. Avrakhov, E. Dosov, E.W. Knight, Y. Zhao
Euclid TechLabs, Solon, Ohio, USA
J.G. Power, J. Shao
ANL, Lemont, Illinois, USA

Funding: This work was supported by DoE SBIR grant # DE-SC0019642.
Beam halo measurement is important for novel x-ray free-electron lasers which have remarkably high repetition rate and average power. We propose diamond as a radiation hard material that can be used to measure the flux of passing particles based on a particle-induced conductivity effect. Our diamond electrodeless monitor is based on a microwave measurement of the change in the resonator coupling and eigenfrequency. For measurements, we put a sensitive diamond sample in a resonator that intercepts the halo. By measuring the change in RF properties of the resonator, one can infer the beam halo parameters scanning across the beam to map its transverse distribution. In recent experiments we used a Vertical Beam Test Stand (VBS), delivered DC electron beam of the 20-200 keV energy with the current up to 50 µA, to characterize several diamond samples. We have designed and fabricated a scanning diamond monitor, based on an X-band resonator, which was tested at Argonne Wakefield Accelerator (AWA) with a multi-MeV electron beam.

Poster WEPAB164 [5.138 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB164

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paper received ※ 14 May 2021 paper accepted ※ 07 June 2021 issue date ※ 31 August 2021

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WEPAB195

Design and Optimization of a Low Frequency RF-Input Coupler for the IsoDAR RFQ

rfq, simulation, cyclotron, multipactoring

3081

M.P. Sangroula, J.M. Conrad, D. Winklehner
MIT, Cambridge, Massachusetts, USA
M. Schuett
BEVATECH, Frankfurt, Germany

Funding: The RFQ-DIP project is supported by National Science Foundation grant \# PHY-1626069 and the Heising-Simons Foundation.
The Isotope Decay-At-Rest experiment (IsoDAR) is a proposed underground experiment which is expected to be a definitive search for sterile neutrinos. IsoDAR uses an especially designed low-frequency spilt-coaxial radio frequency quadrupole (RFQ) to accelerate H²⁺ ions directly from the ion source into the main cyclotron accelerator. This paper mainly focuses on the design and optimization of a low frequency (32.8 MHz) RF-input coupler for the IsoDAR RFQ. Starting with a basic design, we determine its appropriate position for this coupler in the RFQ. Finally, we optimized the design to lower the input power without compromising the coupling efficiency.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB195

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paper received ※ 21 May 2021 paper accepted ※ 30 June 2021 issue date ※ 29 August 2021

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WEPAB225

Transverse and Longitudinal Single Bunch Instabilities in FCC-ee

wakefield, impedance, simulation, collider

3153

E. Carideo, D. Quartullo, F. Zimmermann
CERN, Geneva, Switzerland
D. De Arcangelis
Sapienza University of Rome, Rome, Italy
M. Migliorati, M. Zobov
INFN/LNF, Frascati, Italy

Improving the accuracy of the impedance model of an accelerator is important for keeping beam instabilities and power loss under control. Here, by means of the PyHEAD- TAIL tracking code, we first review the longitudinal mi- crowave instability threshold for FCC-ee by taking into ac- count the longitudinal impedance model evaluated so far. Moreover, we present the results of beam dynamics simula- tions, including both the longitudinal and transverse wake- fields due to the resistive wall, in order to evaluate the influ- ence of the bunch length on the transverse mode coupling instability. The results of the transverse beam dynamics are also compared with the Vlasov solver DELPHI.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB225

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paper received ※ 10 May 2021 paper accepted ※ 01 July 2021 issue date ※ 18 August 2021

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WEPAB227

Mechanism of Longitudinal Single-Bunch Instability in the CERN SPS

impedance, simulation, synchrotron, emittance

3161

I. Karpov
CERN, Meyrin, Switzerland
M. Gadioux
UCD, Dublin, Ireland

Understanding the origin of beam instabilities is essential for reaching the highest performance of proton synchrotrons. In the present work, the Oide-Yokoya eigenvalue method of solving the linearised Vlasov equation was used to shed light on the mechanism of longitudinal single-bunch instability in the CERN SPS. In particular, semi-analytical calculations were done for the full longitudinal impedance model, taking into account the RF nonlinearity. The obtained results agree well with macro-particle simulations and are consistent with available beam measurements. For the first time, the instability has been interpreted as a coupling of radial modes within a single azimuthal mode, due to a strong potential-well distortion of the synchrotron-frequency distribution. To avoid this instability, a higher RF voltage is required at a given emittance. Thus, the instability mechanism is very different from the loss of Landau damping, which, in contrast, is mitigated by a lower RF voltage. This understanding also allowed us to optimise the RF voltage programmes during the acceleration cycle for high-intensity bunches used in the AWAKE experiment at CERN.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB227

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paper received ※ 12 May 2021 paper accepted ※ 01 July 2021 issue date ※ 15 August 2021

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WEPAB235

TMCI Theory of Flat Chambers Revisited

impedance, storage-ring, vacuum, simulation

3181

T.F. Günzel
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

By accounting for the transverse impedance’ quadrupolar component according to the work of R.Lindberg *, no TMCI-instability can be observed in case of a pure horizontal resistive wall impedance of flat vacuum chambers. In order to study this effect more closely, TMCI-theory is reviewed and Lindberg’s work is further developed by including the resonator model as impedance type. The theory is applied to the ALBA-impedance model for the calculation of horizontal TMCI-detuning and threshold. Moreover, a couple of example cases are presented including vertical TMCI-detuning and threshold. Results on both planes are compared to simpler descriptions which account for the quadrupolar impedance effect only by tune shift.
* Ryan Lindberg, Fokker-Planck analysis of transverse collective instabilities in electron storage rings, Phy. Rev. Acc. Beams 19, 124402 (2016)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB235

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 19 August 2021

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WEPAB239

Effect of Chromaticity and Feedback on Transverse Head-Tail Instability

feedback, impedance, damping, storage-ring

3189

V.V. Smaluk, G. Bassi, A. Blednykh, A. Khan
BNL, Upton, New York, USA

Funding: This work was supported by the US Department of Energy under contract DE-SC0012704.
The head-tail instability caused by the beam interaction with short-range wakefields is a major limitation for the single-bunch beam intensity in circular accelerators. The combined effect of the transverse feedback systems and chromaticity suppressing the instability is discussed. Theoretical and experimental studies of the head-tail instability and methods of its mitigation are reviewed. Results of experimental studies of the transverse mode coupling carried out at NSLS-II are compared with the theoretical model and numerical simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB239

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paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 12 August 2021

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WEPAB279

On Wire-Corrector Optimization in the HL-LHC and the Appearance of Special Aspect Ratios

target, optics, insertion, resonance

3297

D. Kaltchev
TRIUMF, Vancouver, Canada

For the two high-luminosity insertions of the Large Hadron Collider (HL-LHC) current bearing wire correctors are intended to mitigate the detrimental effect of long-range beam-beam interactions. With respect to finding the optimum longitudinal location of the wire, two special locations corresponding to the special values 2 and 1/2 of the beta-function aspect ratio have been previously shown to provide simultaneous cancellation of multiple two-dimensional Resonance Driving Terms. This paper attempts to explain the appearance of such special aspect ratios.

Poster WEPAB279 [1.238 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB279

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paper received ※ 14 May 2021 paper accepted ※ 19 July 2021 issue date ※ 13 August 2021

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WEPAB295

Parameter Estimation of Short Pulse Normal-Conducting Standing Wave Cavities

cavity, gun, RF-structure, resonance

3351

S. Pfeiffer, J. Branlard, F. Burkart, M. Hoffmann, H. Schlarb
DESY, Hamburg, Germany

The linear accelerator ARES (Accelerator Research Experiment at SINBAD) is a new research facility at DESY. Electron bunches with a maximum repetition rate of 50 Hz are accelerated to a target energy of 155 MeV. The facility aims for ultra-stable sub-femtosecond arrival-times and high peak-currents at the experiment, placing high demands on the reference distribution and field regulation of the RF structure. In this contribution, we present the physical parameter estimation of key RF properties such as cavity detuning not directly measurable on the RF field decay. The method can be used as a fast monitor of inner cell temperature. The estimated properties are finally compared with the measured ones.

Poster WEPAB295 [0.860 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB295

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paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 26 August 2021

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WEPAB329

LCLS-II Average Current Monitor

cavity, vacuum, simulation, network

3443

P. Borchard, J.S. Hoh
Dymenso LLC, San Francisco, USA

The LCLS-II project at SLAC is a high power upgrade to the existing free-electron laser facility. The LCLS-II Accelerator System will include a new 4 GeV continuous-wave superconducting linear accelerator in the first kilometer of the SLAC linear accelerator tunnel and supplements the existing low power pulsed linac. Average Current Monitors (ACMs) are needed to protect against excessive beam power which might otherwise cause damage to the beam dumps. The ACM cavities are pillbox-shaped stainless steel RF cavity with two radial probe ports with couplers, one radial test port with a coupler, and a mechanism for mechanically fine-tuning the cavity resonant frequency. The ACM RF cavities will be located at points of known or constrained beam energy and will monitor the beam current, a safety system will trip off the beam if the beam power exceeds the allowed value.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB329

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paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 22 August 2021

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WEPAB342

Beam Induced Power Deposition in CERN SPS Injection Kickers

impedance, simulation, HOM, kicker

3490

M.J. Barnes, O. Bjorkqvist
CERN, Geneva 23, Switzerland
K. Kodama
KEK, Ibaraki, Japan

The SPS injection kicker magnets (MKP) were developed in the 1970’s, before beam power deposition was considered an issue and before any advanced tools for analysing beam coupling impedance were available in their current form. These magnets are very lossy from a beam impedance perspective, and the beam induced power deposition is highly non-uniform. This is expected to be an issue during SPS operation with the higher intensity beams needed in the future for HL-LHC. There is an existing design, with serigraphy, that will mitigate the heating issues, which is presently being implemented on a prototype for test and measurement. Models have been developed to aid in predicting the safe operating regions until the upgraded MKPs are installed in the SPS: these are reported herein. A novel measurement technique is also presented to confirm the non-uniform power deposition in the ferrite yoke. Beam coupling impedance, power deposition, field rise time and field uniformity data are also presented for an upgraded, prototype, MKP.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB342

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paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 25 August 2021

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WEPAB345

Impedance and Thermal Studies of the LHC Injection Kicker Magnet Upgrade

kicker, impedance, injection, simulation

3502

M.J. Barnes, O. Bjorkqvist, F. Motschmann
CERN, Geneva 23, Switzerland

The bunch intensities of High Luminosity (HL) LHC are predicted to lead to heating of the ferrite yokes of the LHC injection kicker magnets (MKI), in their current configuration, to their Curie temperature. Hence, the MKIs are being upgraded to meet the requirements of HL-LHC, which is planned to start in the mid-2020s. The upgraded design features an RF damping ferrite loaded structure at the upstream end of each magnet, which will absorb a large portion of the beam induced power deposition of the magnet. The ferrite damper is cooled via a copper sleeve, brazed to the ferrite, and a set of water pipes. The thermal contact conductance (TCC) between ferrite and copper is very important, as are the properties of the ferrite. In this paper, we present measurements of the TCC and ferrite properties. This data is used to predict temperatures during operation of the LHC. In addition, a measurement and prediction is shown for the longitudinal impedance of the magnet. The models developed in this study will be benchmarked during run III of the LHC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB345

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paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 13 August 2021

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WEPAB346

Electromagnetic Modelling of Kicker Magnets to Derive Equivalent Circuits

kicker, simulation, impedance, extraction

3506

M.J. Barnes, O. Bjorkqvist
CERN, Geneva 23, Switzerland
L. Jensen, O.A. Nielsen
Aarhus University, Aarhus, Denmark

An equivalent circuit model of a kicker magnet system is an invaluable tool for predicting the performance, studying possible modifications and for helping to diagnose faults. The frequency content of pulses associated with a ferrite loaded transmission line kicker magnet generally extend up to a few tens of MHz: hence, it is feasible to accurately model such a kicker magnet using lumped elements. This modelling technique is powerful since it in general has a run time several orders of magnitude shorter than a full wave electromagnetic simulation. In this paper, we determine values, including those of parasitic components, using modern simulation tools, for use in the lumped equivalent circuit models. In addition, the paper describes a method to simulate coupling between beam and the electrical circuit of a kicker magnet at relatively low frequencies: this allows one to use circuit analysis tools to study means of mitigating beam induced resonances.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB346

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paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 14 August 2021

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WEPAB349

Design of a Circular Waveguide TM₀₁ Mode Launcher with Wire Loop Feed

GUI, experiment, detector, simulation

3517

A. Chittora
BITS Pilani, Sancoale, India

In Accelerator technology, RF power couplers are important component to couple RF signal to travelling wave structure. Circular waveguide TM₀₁ mode is one of the symmetric modes, that is suitable to use for RF coupling. TM₀₁ mode launcher is used as an RF coupler in Accelerator technology*. Design of a compact circular waveguide TM₀₁ mode-launcher is presented in this paper. The design is based on the principle of magnetic field coupling between a wire loop and TM₀₁ mode of circular waveguide. The mode launcher exhibits high efficiency and 3.1% bandwidth at 3.2 GHz frequency with both circular and elliptical loop. Performance of the mode launcher is experimentally verified and simulated S-parameters agree with the measured results. The mode launcher is of compact size and is suitable for efficient excitation of TM₀₁ mode in circular waveguide and travelling wave structures. The launcher is also useful for cold testing of high power microwave antennas and Radars.
* M. Forno, "Design of a high power TM₀₁ mode launcher optimized for manufacturing by milling." 2016.

Poster WEPAB349 [1.135 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB349

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 20 August 2021

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WEPAB400

Forced Coupling Resonance Driving Terms

dipole, optics, resonance, simulation

3646

A. Wegscheider, R. Tomás García
CERN, Meyrin, Switzerland

At the LHC, coupling is routinely measured using forced oscillations of the beam through excitation with an AC-dipole. The driving of the particle motion has an impact on the measurement of resonance driving terms. Recent findings suggest that the current models describing the forced motion are neglecting a local effect of the AC-dipole, creating a jump of the amplitude of the resonance driving terms. This work presents a study of the improvement of coupling measurements for typical LHC optics as well as its upgrade project HL-LHC, by using the new model.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB400

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paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 20 August 2021

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THPAB001

Reaching the Sub Per Mil Level Coupling Corrections in the LHC

quadrupole, simulation, dipole, operation

3752

E.J. Høydalsvik, T.H.B. Persson
CERN, Geneva, Switzerland

The High Luminosity LHC (HL-LHC) is requiring sub per mil coupling correction, as defined by the closest tune approach. In this article, the current coupling correction strategy is analyzed in order to understand if it can robustly correct to these very low levels. The impact of realistic errors on the coupling correction is investigated with MAD-X simulations, including the influence of local coupling on the global coupling correction. Through simulations and measurements in the LHC, the effect of BPM noise on the coupling correction is analyzed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB001

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paper received ※ 11 May 2021 paper accepted ※ 28 July 2021 issue date ※ 23 August 2021

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THPAB014

Matlab Simulations of the Helium Liquefier in the FREIA Laboratory

simulation, HOM, cavity, interface

3781

E. Waagaard, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden

We describe simulations that track a state vector with pressure, temperature, and gas flow through the helium liquefier in the FREIA laboratory. Most components, including three-way heat exchangers, are represented by matrices that allow us to track the state through the system. The only non-linear element is the Joule-Thomson valve, which is represented by a non-linear map for the state variables. Realistic properties for the enthalpy and other thermodynamic quantities are taken into account with the help of the Coolprop library. The resulting system of equations is rapidly solved by iteration and shows good agreement with the observed LHe yield with and without nitrogen pre-cooling.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB014

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paper received ※ 13 May 2021 paper accepted ※ 14 July 2021 issue date ※ 26 August 2021

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THPAB075

Collective (In)stability Near the Coupling Resonance

wakefield, resonance, simulation, impedance

3933

R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
We show how to treat transverse collective instabilities when operating in the vicinity of the coupling (or tune difference) resonance. We begin by defining the approximate independent degrees of freedom including both linear coupling and chromatic effects. We then show how the destabilizing force due to wakefields and the stabilizing chromatic effects can be described by a linear combination of the horizontal and vertical motion that depends upon how close one is to the resonance. The theory agrees well with tracking studies, and will be relevant for those next-generation storage rings that plan to operate near the coupling resonance to produce nearly round beams, including the multi-bend achromat upgrade for the Advanced Photon Source.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB075

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paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 01 September 2021

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THPAB076

Effects of Chromaticity and Synchrotron Emission on Coupled-Bunch Transverse Stability

damping, simulation, synchrotron, wakefield

3937

R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
We present a theory that can compute the transverse coupled-bunch instability growth rates at any chromaticity and for any longitudinal potential provided only that the long-range wakefield varies slowly over the bunch. The theory is expressed in terms of the usual coupled-bunch eigenvalues at zero chromaticity, and when the longitudinal motion is simple harmonic our solution only requires numerical root-finding that is easy to implement and fast to solve; the more general case requires some additional calculations but is still relatively fast. The theory predicts that the coupled-bunch growth rates can be significantly reduced when the chromatic betatron tune spread is larger than the coupled-bunch growth rate at zero chromaticity. Our theoretical results are compared favorably with tracking simulations for the long-range resistive wall instability, and we also indicate how damping and diffusion from synchrotron emission can further reduce or even stabilize the dynamics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB076

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paper received ※ 20 May 2021 paper accepted ※ 26 July 2021 issue date ※ 26 August 2021

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THPAB081

High-Power Prototype Canon Coupler for APS-U Booster Cavities

cavity, booster, GUI, injection

3956

G.J. Waldschmidt, D.J. Bromberek, D. Horan, G. Trento, U. Wienands
ANL, Lemont, Illinois, USA
T. Harada, H. Oikawa, H. Takahashi
CETD, Tochigi, Japan

The Advanced Photon Source Upgrade (APS-U) plans to achieve a beam capture efficiency above 90% at 17 nC bunch charge into the Booster. Due to large beam loading at injection, the 352-MHz Booster cavities will be significantly detuned necessitating effective-power handling much greater than the 100kW effective power rating of the present coupler. Canon Electron Tubes & Devices Co., Ltd. (CETD) has designed and built a compact coupler for the APS-U Booster using a high-power ceramic disk window design in addition to accommodating significant space restrictions and additional diagnostics and cooling requirements. The coupler design was modified from an existing 500MHz, 800kW coupler that has been in routine operation at KEKB. The APS-U coupler has been installed and tested in the high-power 352-MHz test stand at the APS. The details of the design and testing of the prototype coupler will be reported in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB081

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paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 15 August 2021

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THPAB145

Cold Test of a Novel S-Band 1.6 Cell Photocathode RF Gun

gun, cavity, cathode, simulation

4045

Zh.X. Tang, S.X. Dong, Y.J. Pei, B.F. Wei
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China(Grant No. 11805199 and U1832135) and Fundamental Research Funds for the Central Universities (Grant No. WK2310000072)
The photocathode RF gun is one of the most critical components for high quality electron beam sources. The asymmetric multi-pole field contributes to the transverse emittance growth and degrades the beam quality. In order to overcome the problem, we propose a novel rotationally symmetric 1.6 cell RF gun to construct the symmetric field in this paper. The concrete proposal is that a coaxial cell cavity with a symmetrical distribution of four grooves is concatenated to the photocathode end of the traditional 0.6 cell cavity to form the novel 0.6 cell cavity. Through the detailed design study, the profile of the RF gun is optimized to improve the shunt impedance and mode separation and make the surface peak electric field at the photocathode end. Considering the filling time, a coupling slot is designed to couple input power into the RF gun. The RF cavity is machined by numerical control machine tool, and the tuning and low power RF measurement are carried out. The experimental results are consistent with the simulation results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB145

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paper received ※ 09 May 2021 paper accepted ※ 02 September 2021 issue date ※ 29 August 2021

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THPAB147

Preliminary Study of 500 MHz HOM-Free RF Cavity

cavity, HOM, GUI, damping

4050

Zh.X. Tang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China(Grant No. U1832135 and 11805199)}
In this paper, we study the microwave characteristics of 500 MHz RF cavity, including the optimization of cavity structure, the simulation design of high-order mode (HOM) absorption structure and the design of coupler. The cavity structure is simulated by CST. The absorption waveguide is designed and optimized. The coupler is designed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB147

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paper received ※ 09 May 2021 paper accepted ※ 16 July 2021 issue date ※ 02 September 2021

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THPAB167

Technical Design of an RFQ Injector for the IsoDAR Cyclotron

rfq, cyclotron, cavity, simulation

4075

H. Höltermann, D. Koser, B. Koubek, H. Podlech, U. Ratzinger, M. Schuett, M. Syha
BEVATECH, Frankfurt, Germany
J.M. Conrad, J. Smolsky, L.H. Waites, D. Winklehner
MIT, Cambridge, Massachusetts, USA

For the IsoDAR (Isotope Decay-At-Rest) experiment, a high intensity (10 mA CW) primary proton beam is needed. To generate this beam, H²⁺ is accelerated in a cyclotron and stripped into protons after extraction. An RFQ, partially embedded in the cyclotron yoke, will be used to bunch and axially inject H²⁺ ions into the main accelerator. The strong RFQ bunching capabilities will be used to optimize the overall injection efficiency. To keep the setup compact the distance between the ion source and RFQ can be kept very short as well. In this paper, we describe the technical design of the RFQ. We focus on two critical aspects: 1. The use of a split-coaxial structure, necessitated by the low frequency of 32.8 MHz (matching the cyclotron RF) and the desired small tank diameter; 2. The high current, CW operation, requiring a good cooling concept for the RFQ tank and vanes.

Poster THPAB167 [2.162 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB167

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paper received ※ 14 May 2021 paper accepted ※ 27 July 2021 issue date ※ 21 August 2021

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THPAB171

mm-Wave Linac Design for Next Generation VHEE Cancer Therapy Systems

linac, electron, simulation, impedance

4090

E.J.C. Snively, K.C. Deering, E.A. Nanni
SLAC, Menlo Park, California, USA

Direct electron therapy offers an attractive method for providing the high dose rates necessary for FLASH radiation therapy, a new treatment modality with the potential for enhanced healthy tissue sparing. Direct electron therapy has been limited by the low beam energies, up to 20 MeV, provided by today’s medical linacs, restricting the achievable dose depth to superficial tumors. Very High Energy Electron (VHEE) therapy could reach deep-seated tumors throughout the body. A clinically viable VHEE system must provide electron energies of around 100 MeV in a compact footprint, roughly 1 to 2 meters, with modest power requirements. We investigate the development of mm-wave linacs to provide the necessary beam energies on the sub-meter scale, taking advantage of the favorable scaling of high-frequency operation to support gradients well above 100 MeV/m. We discuss the design parameters necessary for high-efficiency structures, with shunt impedance on the order of 1 GOhm/m, producing high gradients with only a few megawatts of power. We present simulations of cavity performance in the mm-wave operating regime, with an emphasis on compatibility with the requirements of VHEE therapy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB171

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 15 August 2021

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THPAB187

Determination of Required Tolerances and Stop Band Width for Cells Manufacturing and Tuning in Compensated High Energy Accelerating Structures

linac, cavity, hadron, factory

4139

I.V. Rybakov, V.V. Paramonov
RAS/INR, Moscow, Russia

The required value of the spread for accelerating field distribution comes from the beam dynamics conditions and for cavities in high energy hadron linacs is ~1%. The standard deviation of the accelerating field distribution depends on the spread in frequencies of accelerating and coupling cells, stop bandwidth and deviations in coupling coefficients. The deviations in frequencies for accelerating, coupling cells, coupling coefficients, are directly related to tolerances manufacturing tolerances for cells. The stop bandwidth should be adjusted with cell tuning. Relations between the standard deviation of field distribution and deviations in cells parameters* are known. Together with the relation between deviations in cells dimensions and cells parameters** recommendations for cells manufacturing tolerances could be obtained. In relation to the coupling coefficient of compensated accelerating structures (ACS, SCS, CDS, DAW) for high-energy parts of linacs some recommendations for the determination of optimal manufacturing tolerances and acceptable stopband are presented.
* V.F. Vikulov and V.E. Kalyuzhny // Tech. Phys., v. 50, 1980, pp. 773-779
** I.V. Rybakov, V.V. Paramonov, A.K. Skassyrskaya // Proc. RuPAC 2016, pp. 291-293

Poster THPAB187 [0.649 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB187

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paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 24 August 2021

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THPAB241

Examination of Semi-Analytic Model for Mode Coupling Instabilities

space-charge, simulation, transverse-dynamics, damping

4278

M.A. Balcewicz, Y. Hao
FRIB, East Lansing, Michigan, USA
M. Blaskiewicz
BNL, Upton, New York, USA

Funding: Work supported by by Brookhaven Science Associates, LLC under contract number 364776.
A semianalytic model for studying beams at high SC tune shift is shown. It is a generalization of SWM ** /ABS ** for an arbitrary number of longitudinal phase space cycles, yielding more realistic longitudinal physics. The consequences of this generalization are explored; model is benchmarked against TRANFT *** and analytical methods.
* Blaskiewicz, Michael. Phys. Rev. ST Accel. Beams, vol. 1, p. 044201, 1998.
** Burov, Alexey. Phys. Rev. Accel. Beams, vol. 22, p. 034202, 2019.
*** M. Blaskiewicz, in Proc. PAC07, Albuquerque,

Poster THPAB241 [0.894 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB241

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 14 August 2021

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