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MOPR015 |
Beta-beating Estimates and Corrections at SIS100 | |
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| Linear magnet errors cause modifications of accelerator optics. This effect is unwanted and requires proper correction. By using Mad-X we estimate the beta-beating for SIS100, taking into account also the misalignment of the sextupole magnets. The influence of the quadrupole errors on the beta function is discussed and the correction strategy is presented. In view of assessing the effect of space charge we present the dependence of beta-beating on the working point, and discuss the consequences for the correction strategy. | ||
| MOPR016 | Mitigation of Numerical Noise for Beam Loss Simulations | 1 |
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| Numerical noise emerges in self-consistent simulations of charged particles, and its mitigation is investigated since the first numerical studies in plasma physics. In accelerator physics, recent studies find an artificial diffusion of the particle beam due to numerical noise in particle-in-cell tracking, which is of particular importance for high intensity machines with a long storage time, as the SIS100 at FAIR or in context of the LIU upgrade at CERN. In beam loss simulations for these projects artificial effects must be distinguished from physical beam loss. Therefore, it is important to relate artificial diffusion to artificial beam loss, and to choose simulation parameters such that physical beam loss is well resolved. As a practical tool, we therefore suggest a scaling law to find optimal simulation parameters for a given maximum percentage of acceptable artificial beam loss. | ||
TUAM6X01 |
Space Charge Effects on the Third Order Coupled Resonance | |
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| The effect of space charge on bunches stored for long term in a nonlinear lattice can be severe for beam survival. This may be the case in projects as SIS100 at GSI or LIU at CERN. In 2012, for the first time, the effect of space charge on a normal third order coupled resonance was investigated at the CERN-PS. The experimental results have highlighted an unprecedented asymmetric beam response where in the horizontal plane the beam exhibits a thick halo, whereas the vertical profile has only core growth. The quest for explaining these results requires a journey thorough the 4 dimensional dynamics of the coupled resonance investigating the fix-lines, and requires a detailed code-experiment benchmarking also including beam profile benchmarking. This study shows that the experimental results of the 2012 PS measurements can be explained by the dynamics the fixed lines also including the effect of the chromaticity. This open the way for studying the effect of space charge on any high order sum nonlinear coupled resonance. | ||
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Slides TUAM6X01 [7.187 MB] | |
| WEAM1X01 | Code Bench-Marking for Long-Term Tracking and Adaptive Algorithms | 1 |
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At CERN we have ramped up a program to investigate space charge effects in the LHC pre-injectors with high brightness beams and long storage times. This in view of the LIU upgrade project for these accelerators. These studies require massive simulation over large number of turns. To this end we have been looking at all available codes and started collaborations on code development with several laboratories: pyORBIT from SNS, SYNERGIA from Fermilab, MICROMAP from GSI and our in-house MAD-X code with an space charge upgrade. We have agreed with our collaborators to bench-mark all these codes in the framework of the GSI bench-marking suite, in particular the main types of frozen space charge and PIC codes are being tested. We also include a study on the subclass of purely frozen and the adaptive frozen modes both part of MAD-X in comparison with the purely frozen MICROMAP code. Last, we will report on CERN's code development effort to understand and eventually overcome the noise issue in PIC codes.
J. Coupard et al., ‘‘LHC Injectors Upgrade, Technical Design Report, Vol. I: Protons'', LIU Technical Design Report (TDR), CERN-ACC-2014-0337. |
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Slides WEAM1X01 [2.353 MB] | |
FRAM2P01 |
Summary WG-A | |
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| Friday Summary | ||