Paper | Title | Other Keywords | Page |
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MOA1PL01 | Challenges in Understanding Space Charge Dynamics | space-charge, simulation, emittance, synchrotron | 1 |
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Space charge effects in high intensity and high brightness synchrotrons can lead to undesired beam emittance growth, beam halo formation and particle loss. A series of dedicated machine experiments has been performed over the past decade in order to study these effects in the particular regime of long-term beam storage (105-106 turns) as required for certain applications. This paper gives an overview of the present understanding of the underlying beam dynamics mechanisms. In particular it focuses on the space charge induced periodic resonance crossing, which has been identified as the main mechanism causing beam degradation in this regime. The challenges in further progressing with the understanding, the modelling and the mitigation of these space charge effects and the resulting beam degradation are discussed. Furthermore, an outlook for possible future directions of studies is presented. | |||
Slides MOA1PL01 [22.877 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOA1PL01 | ||
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TUA2WD02 | High-Power Beam Operation at J-PARC | operation, simulation, injection, proton | 147 |
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The Japan Proton Accelerator Research Complex (J-PARC) is a multipurpose high-power proton accelerator facility, comprising a 400 MeV linac, a 3 GeV rapid cycling synchrotron (RCS) and a 30 GeV main ring synchrotron (MR). RCS is now providing 500 kW beams to the materials and life science experimental facility (MLF) and its beam power will be increased step by step toward the design value of 1 MW. MR has been operated with the beam power of 500 kW at maximum for the long-baseline neutrino oscillation experiment (T2K). An upgrade plan of MR for the beam power of 1.3 MW for the T2K experiment is promoted with a faster cycling scheme. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUA2WD02 | ||
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TUP1WA02 | Fixed Field Accelerators and Space Charge Modeling | space-charge, focusing, acceleration, synchrotron | 158 |
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The efforts of the Fixed Field Accelerators FFA (formerly known as FFAG accelerators) community to address the high intensity challenge are reviewed. Starting from analytic estimates and linear models for space charge computation, the current possibilities of precise 3D models for start to end modeling are discussed. | |||
Slides TUP1WA02 [9.488 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP1WA02 | ||
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WEA1WA01 | Sum Resonances with Space Charge | space-charge, coherent-effects, experiment, simulation | 226 |
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This presentation will discuss the extension of the theory of the sum resonances with space charge. | |||
Slides WEA1WA01 [5.267 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEA1WA01 | ||
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WEP2PO024 | Resonance Stop-bands Compensation at Booster Ring of HIAF | alignment, injection, betatron, coupling | 315 |
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Booster Ring (BRing) of the new approved High Intensity heavy-ion Accelerator Facility (HIAF) in China is designed to stack 0.3-1.0·1011 number of 238U35+ ions by painting injection and deliver over such intensity beam in extraction. However, depressed tune spread caused by space charge effect crosses the low-order resonance stop-bands after bunching the storage beam. To keep a low beam loss during crossing, stop-band compensation scheme is proposed covering the whole process of RF capture and early acceleration. | |||
Poster WEP2PO024 [1.218 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEP2PO024 | ||
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THA1WD01 | Experience and Perspective of FFAG Accelerator | acceleration, proton, cavity, focusing | 342 |
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Funding: This work was funded by ImPACT Program of Council for Science, Technology and Innovation (Cabinet Office, Government of Japan) This talk is about operational challenge and perspective of Fixed Field Alternating Gradient accelerators, including the recent studies on advanced FFAG for high intensity secondary particles. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THA1WD01 | ||
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THP2WB01 | Revisiting the Longitudinal 90 Degree Limit for Superconducting Linear Accelerators | space-charge, lattice, emittance, focusing | 369 |
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In the design of high-intensity linear accelerators one of the generally adopted criteria is not to exceed a zero-current phase advance per focusing period of 90 degrees in order to avoid the space charge driven envelope instability, or a coinciding fourth order space charge resonance. Recently it was claimed that in certain structures, predominantly applicable to super-conducting linac lattices - such a constraint is not always necessary in the longitudinal plane (I. Hofmann and O. Boine-Frankenheim, Phys. Rev. Lett. 118, 2017). This applies primarily to such focusing structures, where the transverse focusing period only induces a weak space charge dependent modulation in the longitudinal plane, and a different periodicity is applicable to the longitudinal plane. Hence the longitudinal 90 degree stopband is practically absent, and phase advances significantly above 90 degrees should be possible in such structures, with a corresponding additional design freedom. As a consequence, we suggest that the 90 degree rule should no longer be taken as standard criterion in the longitudinal plane of linac design. | |||
Slides THP2WB01 [5.179 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB01 | ||
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THP2WB05 | Halo Formation of the High Intensity Beams in a Periodic Solenoidal Fields | space-charge, focusing, solenoid, lattice | 387 |
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Funding: This research was supported by the National Research Foundation of Korea (Grant No. NRF-2017M1A7A1A02016413). Transport of intense beams over long distances can be restricted by space-charge fields which force the trajectories of charged particles to deviate from the stable regions of propagation. The space-charge fields can be calculated from the density distribution of the beam particles, and Poisson's equation. As the space-charge term is put in the equations of motion, it affects the envelope equations and betatron wave number of a charged particle in the beam. Also, with different initial conditions of the beam particles, there can be perturbations on the matched beam envelopes which can generate a resonant interaction between the beam core and test particles. Unlike for the K-V beam, for nonuniform density beams such as Gaussian beams in the periodic quadrupole or solenoidal focusing fields, there exists higher order terms and non-periodic solutions of beam particle oscillations, which can generate halo regions and chaotic motions during the beam propagation. In this study, we have investigated the higher order resonances and non-periodic solutions of the Gaussian beam in the solenoidal focusing fields to understand halo formation mechanisms of the intense beams. |
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Slides THP2WB05 [2.295 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB05 | ||
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