| Paper | Title | Page |
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| WEPTS068 | A Novel S-Based Symplectic Algorithm for Tracking With Space Charge | 3279 |
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Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0011340 Traditional finite-difference particle-in-cell methods for modeling self-consistent space charge introduce non-Hamiltonian effects that make long-term tracking in storage rings unreliable. Foremost of these is so-called grid heating. Particularly for studies where the Hamiltonian invariants are critical for understanding the beam dynamics, such as nonlinear integrable optics, these spurious effects make interpreting simulation results difficult. To remedy this, we present a novel symplectic spectral space charge algorithm that is free of non-Hamiltonian numerical effects and, therefore, suitable for long-term tracking studies. Results presented here include a detailed study of the solver’s performance under a range of conditions. First, we show benchmarking and convergence studies for different particle shapes and different particle distributions. Then we demonstrate the solver’s ability to preserve Hamiltonian structure by studying the formation of space-charge driven resonances using both our algorithm and traditional PIC. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS068 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| WEPTS070 | First Measurements of Nonlinear Decoherence in the IOTA Ring | 3286 |
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Funding: This work has been supported by the U.S. Department of Energy Office of Science, Office of High Energy Physics under Award No. DE-SC00111340 The Integrable Optics Test Accelerator (IOTA), at Fermi National Laboratory is aimed at testing nonlinear optics for the next generation of high intensity rings. Through use of a special magnetic element the ring is designed to induce a large tune spread with amplitude while maintaining integrable motion. This will allow for the suppression of instabilities in high-intensity beams without significant reduction in dynamic aperture. One important aspect of this is the nonlinear decoherence that occurs when a beam is injected off axis or receives a transverse kick while circulating in the ring. This decoherence has been studied in detail, with simulations, for protons in IOTA both with and without space-charge. However, it has yet to be demonstrated experimentally. During the first phase of the IOTA experimental program, the ring is operated with 100 MeV electrons, allowing for the study of nonlinear optics without the complications introduced by space charge. Here we present measurements taken during the IOTA commissioning, and an analysis of the results. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS070 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| THPMP046 | Knowledge Exchange Within the Particle Accelerator Community via Cloud Computing | 3548 |
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Funding: Work supported by US Department of Energy under Award Nos. DE-SC0011237, DE-SC0011340, DE-SC0018719, DE-SC0015212, DE-SC0017181 and DE-SC0017162. The development, testing and use of particle accelerator modeling codes is a core competency of accelerator research laboratories around the world, and likewise for synchrotron radiation and X-ray optics codes at lightsource facilities. Such codes require time and training to learn a command-line workflow involving multiple input and configuration files, execution on a high-performance server or cluster, post-processing with specialized software and finally visualization. Such workflows are error prone an difficult to reproduce. Cloud computing and UI design are core competencies of RadiaSoft LLC, where the Sirepo* framework is being developed to make state of the art codes available in the browser of any desktop, laptop or tablet. We present our initial successes as real world examples of knowledge exchange (KE) between industry and the research community. This work is leading to broader knowledge exchange throughout the community by facilitating education of students and enabling instantaneous sharing of simulation details between colleagues. Sirepo design objectives include: seamless integration with legacy codes, low barrier to entry for new users, configuration transfer to command line mode, catalog of provenance to aid reproducibility, and simplified collaboration through multimodal sharing. The Sirepo Scientific Gateway** allows users to directly test the software. The combination of intuitive browser-based GUIs and Sirepo’s server-side application container technology enables simplified computational archiving and reproducibility. If embraced by the community, this could become an important asset for the design, commissioning and future upgrade of particle accelerator and X-ray beamline facilities. * Sirepo cloud computing framework, https://github.com/radiasoft/sirepo ** Sirepo Scientific Gateway, https://sirepo.com |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP046 | |
| About • | paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| THPMP047 | Advanced Modeling and Optimization of Thermionic Energy Converters | 3552 |
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Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0017162 Thermionic energy converters (TEC) are a class of thermoelectric devices, which promise improvements to the efficiency and cost of both small- and large-scale electricity generation. A TEC is comprised of a narrowly-separated thermionic emitter and an anode. Simple structures are often space-charge limited as operating temperatures produce currents exceeding the Child-Langmuir limit. We present results from 3D simulations of these devices using the particle-in-cell code Warp, developed at Lawrence Berkeley National Lab. We demonstrate improvements to the Warp code permitting high fidelity simulations of complex device geometries. These improvements include modeling of non-conformal geometries using mesh refinement and cut-cells with a dielectric solver, in addition to importing geometries directly from standard CAD output. In this paper we showcase some of these new features and demonstrate their use. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP047 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |