NAPAC2022 - List of Keywords (lattice)

Paper	Title	Other Keywords	Page
MOPA17	Symplectic Particle Tracking in a Thick Nonlinear McMillan Lens for the Fermilab Integrable Optics Test Accelerator (IOTA)	electron, solenoid, optics, simulation	83
	B.L. Cathey, G. Stancari, T. Zolkin Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The McMillan system is a novel method to increase the tune spread of a beam without decreasing its dynamic aperture due to the system’s integrability. While the ideal system is based on an infinitely thin kick, the physical design requires a thick electron lens, including a solenoid. Particle transport through the lens is difficult to simulate due to the nature of the force on the circulating beam. This paper demonstrates accurate simulation of a thick McMillan lens in a solenoid using symplectic integrators derived from Yoshida’s method.
	Poster MOPA17 [2.290 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA17
About •	Received ※ 03 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 09 October 2022
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MOPA69	Adjoint Optimization Applied to Flat to Round Transformers	solenoid, quadrupole, space-charge, electron	199
	T.M. Antonsen, B.L. Beaudoin, S. Bernal, L. Dovlatyan, I. Haber, P.G. O’Shea, D.F. Sutter UMD, College Park, Maryland, USA
	Funding: This work was supported by DOE-HEP Awards No. DESC0010301 and DESC0022009 We present the numerical optimization, using adjoint techniques, of Flat-to-Round (FTR) transformers operating in the strong self-field limit. FTRs transform an unmagnetized beam that has a high aspect ratio, elliptical spatial cross section, to a round beam in a solenoidal magnetic field. In its simplest form the flat to round conversion is accomplished with a triplet of quadrupoles, and a solenoid. FTR transformers have multiple applications in beam physics research, including manipulating electron beams to cool co-propagating hadron beams. Parameters that can be varied to optimize the FTR conversion are the positions and strengths of the four magnet elements, including the orientations and axial profiles of the quadrupoles and the axial profile and strength of the solenoid’s magnetic field. The adjoint method we employ [1] allows for optimization of the lattice with a minimum computational effort including self-fields. The present model is based on a moment description of the beam. However, the generalization to a particle description will be presented. The optimized designs presented here will be tested in experiments under construction at the University of Maryland. [1] Optimization of Flat to Round Transformers with self-fields using adjoint techniques, L. Dovlatyan, B. Beaudoin, S. Bernal, I. Haber, D. Sutter and TMA, PhysRevAccelBeams.25.044002 (2022).
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA69
About •	Received ※ 03 August 2022 — Revised ※ 25 September 2022 — Accepted ※ 05 December 2022 — Issue date ※ 05 December 2022
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MOPA81	Study of Nonlinear Dynamics in the 4-D Hénon Map Using the Square Matrix Method and Iterative Methods	resonance, dynamic-aperture, linear-dynamics, sextupole	232
	K.J. Anderson, Y. Hao FRIB, East Lansing, Michigan, USA L.H. Yu BNL, Upton, New York, USA
	Funding: Accelerator Stewardship program under award number DE-SC0019403 US Department of Energy, Office of Science, High Energy Physics under award number DE-SC0018362 and Michigan State University The Hénon Map represents a linear lattice with a single sextupole kick. This map has been extensively studied due to its chaotic behavior. The case for the two dimensional phase space has recently been revisited using ideas from KAM theory to create an iterative process that transforms nonlinear perturbed trajectories into rigid rotations. The convergence of this method relates to the resonance structure and can be used as an indicator of the dynamic aperture. The studies of this method have been extended to the four dimensional phase space case which introduces coupling between the transverse coordinates. Hao, Y., Anderson, K., & Yu, L. H. (2021, August). Revisit of Nonlinear Dynamics in Hénon Map Using Square Matrix Method. https://doi.org/10.18429/JACoW-IPAC2021-THPAB016
	Poster MOPA81 [3.103 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA81
About •	Received ※ 19 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 15 August 2022 — Issue date ※ 26 August 2022
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TUYD5	Epitaxial Alkali-Antimonide Photocathodes on Lattice-matched Substrates	cathode, ECR, electron, laser	289
	P. Saha, S.S. Karkare Arizona State University, Tempe, USA E. Echeverria, A. Galdi, J.M. Maxson, C.A. Pennington Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA E.J. Montgomery, S. Poddar Euclid Beamlabs, Bolingbrook, USA
	Alkali-antimonides photocathodes, characterized by high quantum efficiency (QE) and low mean transverse energy (MTE) in the visible range of spectrum, are excellent candidates for electron sources to drive X-ray Free Electron Lasers (XFEL) and Ultrafast Electron Diffraction (UED). A key figure of merit for these applications is the electron beam brightness, which is inversely proportional to MTE. MTE can be limited by nanoscale surface roughness. Recently, we have demonstrated physically and chemically smooth Cs₃Sb cathodes on Strontium Titanate (STO) substrates grown via co-deposition technique. Such flat cathodes could result from a more ordered growth. In this paper, we present RHEED data of co-deposited Cs₃Sb cathodes on STO. Efforts to achieve epitaxial growth of Cs₃Sb on STO are then demonstrated via RHEED. We find that films grown epitaxially on substrates like STO and SiC (previously used to achieve single crystalline Cs₃Sb) exhibit QE higher than the polycrystalline Cs₃Sb cathodes, by an order of magnitude below photoemission threshold. Given the larger QE, lower laser fluence could be used to extract high charge densities, thereby leading to enhanced beam brightness.
	Slides TUYD5 [2.088 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD5
About •	Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 07 September 2022
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TUZE3	Optimizing the Discovery of Underlying Nonlinear Beam Dynamics	simulation, MMI, linear-dynamics, experiment	335
	L.A. Pocher, T.M. Antonsen, L. Dovlatyan, I. Haber, P.G. O’Shea UMD, College Park, Maryland, USA
	Funding: Work supported by US DOE-HEP grants: DE-SC0010301 and DE-SC0022009 One of the DOE-HEP Grand Challenges identified by Nagaitsev et al. relates to the use of virtual particle accelerators for beam prediction and optimization. Useful virtual accelerators rely on efficient and effective methodologies grounded in theory, simulation, and experiment. This paper uses an algorithm called Sparse Identification of Nonlinear Dynamical systems (SINDy), which has not previously been applied to beam physics. We believe the SINDy methodology promises to simplify the optimization of accelerator design and commissioning, particularly where space charge is important. We show how SINDy can be used to discover and identify the underlying differential equation system governing the beam moment evolution. We compare discovered differential equations to theoretical predictions and results from the PIC code WARP modeling. We then integrate the discovered differential system forward in time and compare the results to data analyzed in prior work using a Machine Learning paradigm called Reservoir Computing. Finally, we propose extending our methodology, SINDy for Virtual Accelerators (SINDyVA), to the broader community’s computational and real experiments.
	Slides TUZE3 [3.141 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE3
About •	Received ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 22 August 2022
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TUPA14	Fast First-Order Spin Propagation for Spin Matching and Polarization Optimization with Bmad	polarization, quadrupole, solenoid, electron	369
	J.M. Asimow, G.H. Hoffstaetter, D. Sagan, M.G. Signorelli Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Accurate spin tracking is essential for the simulation and propagation of polarized beams, in which a majority of the particles’ spin point in the same direction. Bmad, an open-sourced library for the simulation of charged particle dynamics, traditionally tracks spin via integrating through each element of a lattice. While exceptionally accurate, this method has the drawback of being slow; at best, the runtime is proportional to the length of the element. By solving the spin transport equation for simple magnet elements, Bmad can reduce this algorithm to constant runtime while maintaining high accuracy. This method, known as "Sprint," enables quicker spin matching and prototyping of lattice designs via Bmad.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA14
About •	Received ※ 30 July 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 August 2022
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TUPA16	Singularity-Free Exact Dipole Bend Transport Equations	dipole, simulation, GUI, framework	375
	D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Department of Energy Exact transport equations for a pure dipole bend (a bend with a dipole field and nothing else) have been derived and formulated to avoid singularities when evaluated. The transport equations include finite edge angles and no assumption is made in terms of the bending field being matched to the curvature of the coordinate system.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA16
About •	Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 16 September 2022
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TUPA17	Beam-Based Alignment of Sextupole Families in the EIC	sextupole, kicker, alignment, closed-orbit	378
	J.C. Wang, G.H. Hoffstaetter, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA C. Montag BNL, Upton, New York, USA
	To steer the closed orbit in a storage ring through the center of its quadrupoles, it is important to accurately know the quadrupole centers relative to nearby beam position monitors. Usually this is achieved by beam-based alignment (BBA). Assuming the quadrupole strength can be changed individually, one finds the BPM reading where changing a quadrupole’s strength does not alter the closed orbit. Since most quadrupoles are powered in series, they can only be varied independently if costly power supplies are added. For the EIC electron storage ring (ESR), we investigate whether sextupole BBA can be used instead. Individually powered sextupole BBA techniques already exist, but most sextupoles are powered in families and cannot be individually changed. We therefore developed a method where a localized bump changes the beam excursion in a single sextupole of a family, turning off all families that also have sextupoles in the bump. The bump amplitude at which the sextupole does not cause a closed orbit kick determines the sextupole’s alignment. This study was made to investigate the precision to which this method can be utilized.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA17
About •	Received ※ 04 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 29 August 2022
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TUPA19	Avoiding Combinatorial Explosion in Simulation of Multiple Magnet Errors in Swap-Out Safety Tracking for the Advanced Photon Source Upgrade	photon, simulation, injection, storage-ring	386
	M. Borland, R. Soliday 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. The Advanced Photon Source (APS) is upgrading the storage ring to a hybrid seven-bend-achromat design with reverse bends, providing a natural emittance of 41 pm at 6 GeV. The small dynamic acceptance entails operation in on-axis swap-out mode. Careful consideration is required of the safety implications of injection with shutters open. Tracking studies require simulation of multiple simultaneous magnet errors, some combinations of which may introduce potentially dangerous conditions. A naive grid scan of possible errors, while potentially very complete, would be prohibitively time-consuming. We describe a different approach using biased sampling of particle distributions from successive scans. We also describe other aspects of the simulations, such as use of 3D field maps and a highly detailed aperture model.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA19
About •	Received ※ 01 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 10 September 2022
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TUPA26	Fringe Field Maps for Cartesian Dipoles with Longitudinal and/or Transverse Gradients	dipole, quadrupole, photon, focusing	401
	R.R. Lindberg, M. Borland ANL, Lemont, Illinois, USA
	Funding: This work was supported by U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357. Fringe fields effects in dipoles can give rise to important linear and nonlinear contributions. This paper describes how to extend the classic results of Brown [1] and the more recent calculations of Hwang and Lee [2] to Cartesian dipoles with transverse and/or longitudinal gradients. We do this by 1) introducing a more general definition of the fringe field that can be applied to longitudinal gradient dipoles, 2) allowing for quadrupole and/or sextupole content in the magnet body, and 3) showing how to employ the resulting fringe field maps as a symplectic transformation of the coordinates. We compare our calculation results with tracking for longitudinal and transverse gradient dipoles planned for the APS-U. [1] K.L. Brown, Report SLAC-75, 1982. [2] K. Hwang and S.Y. Lee, Phys. Rev. Accel. Beams, vol. 18, p. 122401 2015.
	Poster TUPA26 [2.090 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA26
About •	Received ※ 26 July 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 21 August 2022
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TUPA36	The Advanced Photon Source Linac Extension Area Beamline	electron, gun, linac, photon	430
	K.P. Wootton, W. Berg, J.M. Byrd, J.C. Dooling, G.I. Fystro, A.H. Lumpkin, Y. Sun, A. Zholents ANL, Lemont, Illinois, USA C.C. Hall RadiaSoft LLC, Boulder, Colorado, USA
	Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The Linac Extension Area at the Advanced Photon Source is a flexible beamline area for testing accelerator components and techniques. Driven by the Advanced Photon Source electron linac equipped with a photocathode RF electron gun, the Linac Extension Area houses a 12 m long beamline. The beamline is furnished with YAG screens, BPMs and a magnetic spectrometer to assist with characterization of beam emittance and energy spread. A 1.4 m long insertion in the middle of the beamline is provided for the installation of a device under test. The beamline is expected to be available soon for testing accelerator components and techniques using round and flat electron beams over an energy range 150-450 MeV. In the present work, we describe this beamline and summarise the main beam parameters.
	Poster TUPA36 [0.892 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA36
About •	Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 19 September 2022
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TUPA48	Effect of Lattice Misalignments on Beam Dynamics in LANSCE Linear Accelerator	alignment, emittance, linac, simulation	455
	Y.K. Batygin, S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by US DOE under contract 89233218CNA000001 Accelerator channel misalignments can significantly affect beam parameters in long linear accelerators. Measurements of misalignments of the LANSCE linac lattice elements was performed by the Mechanical Design Engineering Group of the Los Alamos Accelerator Operations and Technology Division. In order to determine effect of misalignment on beam parameters in LANSCE linac, the start-to-end simulations of LANSCE accelerator were performed using Beampath and CST codes including measured displacements of quadrupoles and accelerating tanks. Simulations were done for both H⁺ and H⁻ beams with various beam flavors. Effect of misalignments was compared with those due to beam space charge and distortion of RF field along the channel. Paper presents results of simulation and comparison with experimental data of beam emittance growth along the machine.
	Poster TUPA48 [1.547 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA48
About •	Received ※ 23 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 04 August 2022 — Issue date ※ 14 August 2022
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WEXD2	Storage Ring Tracking Using Generalized Gradient Representations of Full Magnetic Field Maps	dipole, emittance, quadrupole, sextupole	542
	R.R. Lindberg, M. Borland ANL, Lemont, Illinois, USA
	Funding: This work was supported by U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357. We have developed a set of tools to simulate particle dynamics in the full magnetic field using the generalized gradients representation. Generalized gradients provide accurate and analytic representations of the magnetic field that allow for symplectic tracking [1]. We describe the tools that convert magnetic field data into generalized gradients representations suitable for tracking in Elegant, and discuss recent results based upon tracking with the full field representations for all magnets in the APS-U storage ring. [1] A. Dragt. Lie Methods for Nonlinear Dynamics with Applications to Accelerator Physics. University of Maryland (2019).
	Slides WEXD2 [3.841 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEXD2
About •	Received ※ 16 July 2022 — Accepted ※ 29 July 2022 — Issue date ※ 04 August 2022
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WEXD3	Map Tracking Including the Effect of Stochastic Radiation	radiation, emittance, damping, photon	548
	D. Sagan, G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA E. Forest KEK, Ibaraki, Japan
	Funding: Department of Energy Using transfer maps to simulate charged particle motion in accelerators is advantageous since it is much faster than tracking step-by-step. One challenge to using transfer maps is to properly include radiation effects. The effect of radiation can be divided into deterministic and stochastic parts. While computation of the deterministic effect has been previously reported, handling of the stochastic part has not. In this paper, an algorithm for including the stochastic effect is presented including taking into account the finite opening angle of the emitted photons. A comparison demonstrates the utility of this approach. Generating maps which include radiation has been implemented in the PTC software library which is interfaced to the Bmad toolkit.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEXD3
About •	Received ※ 06 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 24 August 2022
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WEPA68	Record Quantum Efficiency from Superlattice Photocathode for Spin Polarized Electron Beam Production	electron, cathode, polarization, distributed	784
	J.P. Biswas, L. Cultrera, K. Kisslinger, W. Liu, J. Skarita, E. Wang BNL, Upton, New York, USA S.D. Hawkins, J.F. Klem, S.R. Lee Sandia National Laboratories, Albuquerque, New Mexico, USA
	Funding: The work is supported by Brookhaven Science Associates, LLC under Contract DESC0012704 with the U.S. DOE. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. Electron sources producing highly spin-polarized electron beams are currently possible only with photocathodes based on GaAs and other III-V semiconductors. GaAs/GaAsP superlattice (SL) photocathodes with a distributed Bragg reflector (DBR) represent the state of the art for the production of spin-polarized electrons. We present results on a SL-DBR GaAs/GaAsP structure designed to leverage strain compensation to achieve simultaneously high QE and spin polarization. These photocathode structures were grown using molecular beam epitaxy and achieved quantum efficiencies exceeding 15% and electron spin polarization of about 75% when illuminated with near bandgap photon energies.
	Poster WEPA68 [4.506 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA68
About •	Received ※ 20 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 10 August 2022
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WEPA74	Characterization of Fully Coupled Linear Optics with Turn-by-Turn Data	optics, coupling, resonance, quadrupole	805
	Y. Li, R.S. Rainer, V.V. Smaluk BNL, Upton, New York, USA
	Funding: This research used resources of the NSLS-II, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. In the future diffraction-limited light source rings, fully coupled linear optics to generate round beams is preferable. While machine tune approaching to linear difference resonances, small random errors, such as quadrupole rolls, can result in fully coupled optics. Consequently, some uncertainty exists in such optics due to random errors distributions. Given beam position monitors turn-by-turn readings, the harmonic analysis method was used to characterize the coupled Ripken Twiss parameters.
	Poster WEPA74 [0.889 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA74
About •	Received ※ 25 July 2022 — Revised ※ 30 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 19 August 2022
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WEPA77	A New PCB Rotating Coil at NSLS-II	quadrupole, dipole, emittance, permanent-magnet	816
	M. Musardo, J. Avronsart, F.A. DePaola, L. Doom, R. Faussete, F.C. Lincoln, S.K. Sharma, T. Tanabe BNL, Upton, New York, USA D. Assell, J. DiMarco Fermilab, Batavia, Illinois, USA A. Banerjee SBU, Stony Brook, New York, USA C.L. Doose, A.K. Jain ANL, Lemont, Illinois, USA
	Several R&D projects are underway at NSLS-II towards an upgrade of its storage ring with a new lattice that will use high field magnets with small bores of 16-22 mm. A large fraction of the high field magnets are expected to be of permanent magnet technology that will require precise magnetic measurements and field harmonics corrections. A new magnetic measurement bench has been built based on a printed circuit board (PCB) coil of 12 mm diameter and 270 mm active length. This PCB coil has the capabil-ity of measuring field quality to a level of 10 ppm of the main field up to the 15th harmonic with a sensitivity between 0.01 m2 and 0.02 m2 at the reference radius of 5 mm. This paper will describe the main features of the rotating coil bench and discuss the measurement results of a permanent-magnet Halbach quadrupole of 12.7 mm bore diameter.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA77
About •	Received ※ 28 July 2022 — Revised ※ 06 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 29 August 2022
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WEPA80	Progress on Convergence Map Based on Square Matrix for Nonlinear Lattice Optimization	dynamic-aperture, resonance, storage-ring, linear-dynamics	823
	L.H. Yu, Y. Hao, Y. Hidaka, F. Plassard, V.V. Smaluk BNL, Upton, New York, USA Y. Hao FRIB, East Lansing, Michigan, USA
	Funding: DOE. We report progress on applying the square matrix method to obtain in high speed a "convergence map", which is similar but different from a frequency map. We give an example of applying the method to optimize a nonlinear lattice for the NSLS-II upgrade. The convergence map is obtained by solving the nonlinear dynamical equation by iteration of the perturbation method and studying the convergence. The map provides information about the stability border of the dynamical aperture. We compare the map with the frequency map from tracking. The result in our example of nonlinear optimization of the NSLS-II lattice shows the new method may be applied in nonlinear lattice optimization, taking advantage of the high speed (about 30~300 times faster) to explore x, y, and the off-momentum phase space.
	Poster WEPA80 [5.392 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA80
About •	Received ※ 19 July 2022 — Revised ※ 26 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022
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Paper

Title

Other Keywords

Page

Symplectic Particle Tracking in a Thick Nonlinear McMillan Lens for the Fermilab Integrable Optics Test Accelerator (IOTA)

electron, solenoid, optics, simulation

83

B.L. Cathey, G. Stancari, T. Zolkin
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The McMillan system is a novel method to increase the tune spread of a beam without decreasing its dynamic aperture due to the system’s integrability. While the ideal system is based on an infinitely thin kick, the physical design requires a thick electron lens, including a solenoid. Particle transport through the lens is difficult to simulate due to the nature of the force on the circulating beam. This paper demonstrates accurate simulation of a thick McMillan lens in a solenoid using symplectic integrators derived from Yoshida’s method.

Poster MOPA17 [2.290 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA17

About •

Received ※ 03 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 09 October 2022

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MOPA69

Adjoint Optimization Applied to Flat to Round Transformers

solenoid, quadrupole, space-charge, electron

199

T.M. Antonsen, B.L. Beaudoin, S. Bernal, L. Dovlatyan, I. Haber, P.G. O’Shea, D.F. Sutter
UMD, College Park, Maryland, USA

Funding: This work was supported by DOE-HEP Awards No. DESC0010301 and DESC0022009
We present the numerical optimization, using adjoint techniques, of Flat-to-Round (FTR) transformers operating in the strong self-field limit. FTRs transform an unmagnetized beam that has a high aspect ratio, elliptical spatial cross section, to a round beam in a solenoidal magnetic field. In its simplest form the flat to round conversion is accomplished with a triplet of quadrupoles, and a solenoid. FTR transformers have multiple applications in beam physics research, including manipulating electron beams to cool co-propagating hadron beams. Parameters that can be varied to optimize the FTR conversion are the positions and strengths of the four magnet elements, including the orientations and axial profiles of the quadrupoles and the axial profile and strength of the solenoid’s magnetic field. The adjoint method we employ [1] allows for optimization of the lattice with a minimum computational effort including self-fields. The present model is based on a moment description of the beam. However, the generalization to a particle description will be presented. The optimized designs presented here will be tested in experiments under construction at the University of Maryland.
[1] Optimization of Flat to Round Transformers with self-fields using adjoint techniques, L. Dovlatyan, B. Beaudoin, S. Bernal, I. Haber, D. Sutter and TMA, PhysRevAccelBeams.25.044002 (2022).

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA69

About •

Received ※ 03 August 2022 — Revised ※ 25 September 2022 — Accepted ※ 05 December 2022 — Issue date ※ 05 December 2022

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

MOPA81

Study of Nonlinear Dynamics in the 4-D Hénon Map Using the Square Matrix Method and Iterative Methods

resonance, dynamic-aperture, linear-dynamics, sextupole

232

K.J. Anderson, Y. Hao
FRIB, East Lansing, Michigan, USA
L.H. Yu
BNL, Upton, New York, USA

Funding: Accelerator Stewardship program under award number DE-SC0019403 US Department of Energy, Office of Science, High Energy Physics under award number DE-SC0018362 and Michigan State University
The Hénon Map represents a linear lattice with a single sextupole kick. This map has been extensively studied due to its chaotic behavior. The case for the two dimensional phase space has recently been revisited using ideas from KAM theory to create an iterative process that transforms nonlinear perturbed trajectories into rigid rotations*. The convergence of this method relates to the resonance structure and can be used as an indicator of the dynamic aperture. The studies of this method have been extended to the four dimensional phase space case which introduces coupling between the transverse coordinates.
*Hao, Y., Anderson, K., & Yu, L. H. (2021, August). Revisit of Nonlinear Dynamics in Hénon Map Using Square Matrix Method. https://doi.org/10.18429/JACoW-IPAC2021-THPAB016

Poster MOPA81 [3.103 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA81

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Received ※ 19 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 15 August 2022 — Issue date ※ 26 August 2022

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TUYD5

Epitaxial Alkali-Antimonide Photocathodes on Lattice-matched Substrates

cathode, ECR, electron, laser

289

P. Saha, S.S. Karkare
Arizona State University, Tempe, USA
E. Echeverria, A. Galdi, J.M. Maxson, C.A. Pennington
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
E.J. Montgomery, S. Poddar
Euclid Beamlabs, Bolingbrook, USA

Alkali-antimonides photocathodes, characterized by high quantum efficiency (QE) and low mean transverse energy (MTE) in the visible range of spectrum, are excellent candidates for electron sources to drive X-ray Free Electron Lasers (XFEL) and Ultrafast Electron Diffraction (UED). A key figure of merit for these applications is the electron beam brightness, which is inversely proportional to MTE. MTE can be limited by nanoscale surface roughness. Recently, we have demonstrated physically and chemically smooth Cs₃Sb cathodes on Strontium Titanate (STO) substrates grown via co-deposition technique. Such flat cathodes could result from a more ordered growth. In this paper, we present RHEED data of co-deposited Cs₃Sb cathodes on STO. Efforts to achieve epitaxial growth of Cs₃Sb on STO are then demonstrated via RHEED. We find that films grown epitaxially on substrates like STO and SiC (previously used to achieve single crystalline Cs₃Sb) exhibit QE higher than the polycrystalline Cs₃Sb cathodes, by an order of magnitude below photoemission threshold. Given the larger QE, lower laser fluence could be used to extract high charge densities, thereby leading to enhanced beam brightness.

Slides TUYD5 [2.088 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD5

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Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 07 September 2022

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TUZE3

Optimizing the Discovery of Underlying Nonlinear Beam Dynamics

simulation, MMI, linear-dynamics, experiment

335

L.A. Pocher, T.M. Antonsen, L. Dovlatyan, I. Haber, P.G. O’Shea
UMD, College Park, Maryland, USA

Funding: Work supported by US DOE-HEP grants: DE-SC0010301 and DE-SC0022009
One of the DOE-HEP Grand Challenges identified by Nagaitsev et al. relates to the use of virtual particle accelerators for beam prediction and optimization. Useful virtual accelerators rely on efficient and effective methodologies grounded in theory, simulation, and experiment. This paper uses an algorithm called Sparse Identification of Nonlinear Dynamical systems (SINDy), which has not previously been applied to beam physics. We believe the SINDy methodology promises to simplify the optimization of accelerator design and commissioning, particularly where space charge is important. We show how SINDy can be used to discover and identify the underlying differential equation system governing the beam moment evolution. We compare discovered differential equations to theoretical predictions and results from the PIC code WARP modeling. We then integrate the discovered differential system forward in time and compare the results to data analyzed in prior work using a Machine Learning paradigm called Reservoir Computing. Finally, we propose extending our methodology, SINDy for Virtual Accelerators (SINDyVA), to the broader community’s computational and real experiments.

Slides TUZE3 [3.141 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE3

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Received ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 22 August 2022

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TUPA14

Fast First-Order Spin Propagation for Spin Matching and Polarization Optimization with Bmad

polarization, quadrupole, solenoid, electron

369

J.M. Asimow, G.H. Hoffstaetter, D. Sagan, M.G. Signorelli
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Accurate spin tracking is essential for the simulation and propagation of polarized beams, in which a majority of the particles’ spin point in the same direction. Bmad, an open-sourced library for the simulation of charged particle dynamics, traditionally tracks spin via integrating through each element of a lattice. While exceptionally accurate, this method has the drawback of being slow; at best, the runtime is proportional to the length of the element. By solving the spin transport equation for simple magnet elements, Bmad can reduce this algorithm to constant runtime while maintaining high accuracy. This method, known as "Sprint," enables quicker spin matching and prototyping of lattice designs via Bmad.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA14

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Received ※ 30 July 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 August 2022

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TUPA16

Singularity-Free Exact Dipole Bend Transport Equations

dipole, simulation, GUI, framework

375

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

Funding: Department of Energy
Exact transport equations for a pure dipole bend (a bend with a dipole field and nothing else) have been derived and formulated to avoid singularities when evaluated. The transport equations include finite edge angles and no assumption is made in terms of the bending field being matched to the curvature of the coordinate system.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA16

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Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 16 September 2022

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TUPA17

Beam-Based Alignment of Sextupole Families in the EIC

sextupole, kicker, alignment, closed-orbit

378

J.C. Wang, G.H. Hoffstaetter, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
C. Montag
BNL, Upton, New York, USA

To steer the closed orbit in a storage ring through the center of its quadrupoles, it is important to accurately know the quadrupole centers relative to nearby beam position monitors. Usually this is achieved by beam-based alignment (BBA). Assuming the quadrupole strength can be changed individually, one finds the BPM reading where changing a quadrupole’s strength does not alter the closed orbit. Since most quadrupoles are powered in series, they can only be varied independently if costly power supplies are added. For the EIC electron storage ring (ESR), we investigate whether sextupole BBA can be used instead. Individually powered sextupole BBA techniques already exist, but most sextupoles are powered in families and cannot be individually changed. We therefore developed a method where a localized bump changes the beam excursion in a single sextupole of a family, turning off all families that also have sextupoles in the bump. The bump amplitude at which the sextupole does not cause a closed orbit kick determines the sextupole’s alignment. This study was made to investigate the precision to which this method can be utilized.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA17

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Received ※ 04 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 29 August 2022

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TUPA19

Avoiding Combinatorial Explosion in Simulation of Multiple Magnet Errors in Swap-Out Safety Tracking for the Advanced Photon Source Upgrade

photon, simulation, injection, storage-ring

386

M. Borland, R. Soliday
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.
The Advanced Photon Source (APS) is upgrading the storage ring to a hybrid seven-bend-achromat design with reverse bends, providing a natural emittance of 41 pm at 6 GeV. The small dynamic acceptance entails operation in on-axis swap-out mode. Careful consideration is required of the safety implications of injection with shutters open. Tracking studies require simulation of multiple simultaneous magnet errors, some combinations of which may introduce potentially dangerous conditions. A naive grid scan of possible errors, while potentially very complete, would be prohibitively time-consuming. We describe a different approach using biased sampling of particle distributions from successive scans. We also describe other aspects of the simulations, such as use of 3D field maps and a highly detailed aperture model.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA19

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Received ※ 01 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 10 September 2022

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TUPA26

Fringe Field Maps for Cartesian Dipoles with Longitudinal and/or Transverse Gradients

dipole, quadrupole, photon, focusing

401

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

Funding: This work was supported by U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357.
Fringe fields effects in dipoles can give rise to important linear and nonlinear contributions. This paper describes how to extend the classic results of Brown [1] and the more recent calculations of Hwang and Lee [2] to Cartesian dipoles with transverse and/or longitudinal gradients. We do this by 1) introducing a more general definition of the fringe field that can be applied to longitudinal gradient dipoles, 2) allowing for quadrupole and/or sextupole content in the magnet body, and 3) showing how to employ the resulting fringe field maps as a symplectic transformation of the coordinates. We compare our calculation results with tracking for longitudinal and transverse gradient dipoles planned for the APS-U.
[1] K.L. Brown, Report SLAC-75, 1982.
[2] K. Hwang and S.Y. Lee, Phys. Rev. Accel. Beams, vol. 18, p. 122401 2015.

Poster TUPA26 [2.090 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA26

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Received ※ 26 July 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 21 August 2022

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TUPA36

The Advanced Photon Source Linac Extension Area Beamline

electron, gun, linac, photon

430

K.P. Wootton, W. Berg, J.M. Byrd, J.C. Dooling, G.I. Fystro, A.H. Lumpkin, Y. Sun, A. Zholents
ANL, Lemont, Illinois, USA
C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA

Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
The Linac Extension Area at the Advanced Photon Source is a flexible beamline area for testing accelerator components and techniques. Driven by the Advanced Photon Source electron linac equipped with a photocathode RF electron gun, the Linac Extension Area houses a 12 m long beamline. The beamline is furnished with YAG screens, BPMs and a magnetic spectrometer to assist with characterization of beam emittance and energy spread. A 1.4 m long insertion in the middle of the beamline is provided for the installation of a device under test. The beamline is expected to be available soon for testing accelerator components and techniques using round and flat electron beams over an energy range 150-450 MeV. In the present work, we describe this beamline and summarise the main beam parameters.

Poster TUPA36 [0.892 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA36

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Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 19 September 2022

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TUPA48

Effect of Lattice Misalignments on Beam Dynamics in LANSCE Linear Accelerator

alignment, emittance, linac, simulation

455

Y.K. Batygin, S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by US DOE under contract 89233218CNA000001
Accelerator channel misalignments can significantly affect beam parameters in long linear accelerators. Measurements of misalignments of the LANSCE linac lattice elements was performed by the Mechanical Design Engineering Group of the Los Alamos Accelerator Operations and Technology Division. In order to determine effect of misalignment on beam parameters in LANSCE linac, the start-to-end simulations of LANSCE accelerator were performed using Beampath and CST codes including measured displacements of quadrupoles and accelerating tanks. Simulations were done for both H⁺ and H⁻ beams with various beam flavors. Effect of misalignments was compared with those due to beam space charge and distortion of RF field along the channel. Paper presents results of simulation and comparison with experimental data of beam emittance growth along the machine.

Poster TUPA48 [1.547 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA48

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Received ※ 23 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 04 August 2022 — Issue date ※ 14 August 2022

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WEXD2

Storage Ring Tracking Using Generalized Gradient Representations of Full Magnetic Field Maps

dipole, emittance, quadrupole, sextupole

542

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

Funding: This work was supported by U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357.
We have developed a set of tools to simulate particle dynamics in the full magnetic field using the generalized gradients representation. Generalized gradients provide accurate and analytic representations of the magnetic field that allow for symplectic tracking [1]. We describe the tools that convert magnetic field data into generalized gradients representations suitable for tracking in Elegant, and discuss recent results based upon tracking with the full field representations for all magnets in the APS-U storage ring.
[1] A. Dragt. Lie Methods for Nonlinear Dynamics with Applications to Accelerator Physics. University of Maryland (2019).

Slides WEXD2 [3.841 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEXD2

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Received ※ 16 July 2022 — Accepted ※ 29 July 2022 — Issue date ※ 04 August 2022

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WEXD3

Map Tracking Including the Effect of Stochastic Radiation

radiation, emittance, damping, photon

548

D. Sagan, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
E. Forest
KEK, Ibaraki, Japan

Funding: Department of Energy
Using transfer maps to simulate charged particle motion in accelerators is advantageous since it is much faster than tracking step-by-step. One challenge to using transfer maps is to properly include radiation effects. The effect of radiation can be divided into deterministic and stochastic parts. While computation of the deterministic effect has been previously reported, handling of the stochastic part has not. In this paper, an algorithm for including the stochastic effect is presented including taking into account the finite opening angle of the emitted photons. A comparison demonstrates the utility of this approach. Generating maps which include radiation has been implemented in the PTC software library which is interfaced to the Bmad toolkit.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEXD3

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Received ※ 06 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 24 August 2022

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WEPA68

Record Quantum Efficiency from Superlattice Photocathode for Spin Polarized Electron Beam Production

electron, cathode, polarization, distributed

784

J.P. Biswas, L. Cultrera, K. Kisslinger, W. Liu, J. Skarita, E. Wang
BNL, Upton, New York, USA
S.D. Hawkins, J.F. Klem, S.R. Lee
Sandia National Laboratories, Albuquerque, New Mexico, USA

Funding: The work is supported by Brookhaven Science Associates, LLC under Contract DESC0012704 with the U.S. DOE. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
Electron sources producing highly spin-polarized electron beams are currently possible only with photocathodes based on GaAs and other III-V semiconductors. GaAs/GaAsP superlattice (SL) photocathodes with a distributed Bragg reflector (DBR) represent the state of the art for the production of spin-polarized electrons. We present results on a SL-DBR GaAs/GaAsP structure designed to leverage strain compensation to achieve simultaneously high QE and spin polarization. These photocathode structures were grown using molecular beam epitaxy and achieved quantum efficiencies exceeding 15% and electron spin polarization of about 75% when illuminated with near bandgap photon energies.

Poster WEPA68 [4.506 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA68

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Received ※ 20 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 10 August 2022

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WEPA74

Characterization of Fully Coupled Linear Optics with Turn-by-Turn Data

optics, coupling, resonance, quadrupole

805

Y. Li, R.S. Rainer, V.V. Smaluk
BNL, Upton, New York, USA

Funding: This research used resources of the NSLS-II, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.
In the future diffraction-limited light source rings, fully coupled linear optics to generate round beams is preferable. While machine tune approaching to linear difference resonances, small random errors, such as quadrupole rolls, can result in fully coupled optics. Consequently, some uncertainty exists in such optics due to random errors distributions. Given beam position monitors turn-by-turn readings, the harmonic analysis method was used to characterize the coupled Ripken Twiss parameters.

Poster WEPA74 [0.889 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA74

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Received ※ 25 July 2022 — Revised ※ 30 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 19 August 2022

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WEPA77

A New PCB Rotating Coil at NSLS-II

quadrupole, dipole, emittance, permanent-magnet

816

M. Musardo, J. Avronsart, F.A. DePaola, L. Doom, R. Faussete, F.C. Lincoln, S.K. Sharma, T. Tanabe
BNL, Upton, New York, USA
D. Assell, J. DiMarco
Fermilab, Batavia, Illinois, USA
A. Banerjee
SBU, Stony Brook, New York, USA
C.L. Doose, A.K. Jain
ANL, Lemont, Illinois, USA

Several R&D projects are underway at NSLS-II towards an upgrade of its storage ring with a new lattice that will use high field magnets with small bores of 16-22 mm. A large fraction of the high field magnets are expected to be of permanent magnet technology that will require precise magnetic measurements and field harmonics corrections. A new magnetic measurement bench has been built based on a printed circuit board (PCB) coil of 12 mm diameter and 270 mm active length. This PCB coil has the capabil-ity of measuring field quality to a level of 10 ppm of the main field up to the 15th harmonic with a sensitivity between 0.01 m2 and 0.02 m2 at the reference radius of 5 mm. This paper will describe the main features of the rotating coil bench and discuss the measurement results of a permanent-magnet Halbach quadrupole of 12.7 mm bore diameter.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA77

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Received ※ 28 July 2022 — Revised ※ 06 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 29 August 2022

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WEPA80

Progress on Convergence Map Based on Square Matrix for Nonlinear Lattice Optimization

dynamic-aperture, resonance, storage-ring, linear-dynamics

823

L.H. Yu, Y. Hao, Y. Hidaka, F. Plassard, V.V. Smaluk
BNL, Upton, New York, USA
Y. Hao
FRIB, East Lansing, Michigan, USA

Funding: DOE.
We report progress on applying the square matrix method to obtain in high speed a "convergence map", which is similar but different from a frequency map. We give an example of applying the method to optimize a nonlinear lattice for the NSLS-II upgrade. The convergence map is obtained by solving the nonlinear dynamical equation by iteration of the perturbation method and studying the convergence. The map provides information about the stability border of the dynamical aperture. We compare the map with the frequency map from tracking. The result in our example of nonlinear optimization of the NSLS-II lattice shows the new method may be applied in nonlinear lattice optimization, taking advantage of the high speed (about 30~300 times faster) to explore x, y, and the off-momentum phase space.

Poster WEPA80 [5.392 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA80

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Received ※ 19 July 2022 — Revised ※ 26 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022

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