| Paper | Title | Page |
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| MOPAB039 | Amplitude-Dependent Shift of Betatron Tunes and Its Relation to Long-Term Circumference Variations at NSLS-II | 175 |
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| The comparison of amplitude tune dependence measured for NSLSII lattices with models indicated the large change of amplitude tune dependence over time apparently can not be solely explained by magnets variation or beta function changes, but it seems can be explained by energy changes. On the other hand, the energy change required by fitting with the amplitude tune dependence change is too large to be explained by the RF frequency change and the change of the sum of correctors in the period of the measurements. To explain this apparent contradiction, our analysis shows the long term storage ring circumference change can explain the apparent energy change. Our data indeed shows a seasonal change of the amplitude tune dependence over long term observation. This clearly also indicated a relation to long term closed orbit drift. Hence the current work indicates a new strategy to study how to use amplitude tune dependence as a guideline to analyze long term lattice parameter shifts and closed orbit drift, and improve the orbit and machine performance stability. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB039 | |
| About • | paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021 | |
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| MOPAB040 | Gain of Hard X-Ray Fel at 3 GeV and Required Parameters | 178 |
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| We develop a tool for the calculation to study the conditions for a hard x-ray FEL oscillator based on an electron beam in the medium energy range from 3 to 4.5 GeV. We show that the approach developed by K.J. Kim et al. for the small-signal low gain formula can be modified so that the gain can be derived without taking the "no focusing approximation" adopted in the approach so that a strong focusing can be applied. We also derive the formula to allow for the gain calculation of harmonic lasing. The gain in this formula can be cast in the form of a product of two factors with one of them only depends on the harmonic number, undulator period, and gap. Thus this factor can be used to show that it is favorable to use harmonic lasing to achieve hard x-ray FEL working in the medium energy range and in the small-signal low gain regime. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB040 | |
| About • | paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 10 August 2021 | |
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| MOPAB041 | Convergence Map with Action-Angle Variables Based on Square Matrix for Nonlinear Lattice Optimization | 182 |
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| We apply square matrix method to obtain in high speed a "convergence map", which is similar but different from frequency map. The convergence map is obtained from solving nonlinear dynamical equation by iteration of perturbation method and study the convergence. The map provides information about the stability border of dynamical aperture. We compare the map with frequency map from tracking. The result indicates the new method may be applied in nonlinear lattice optimization, taking the advantage of the high speed (about 10~50 times faster) to explore x, y and the off-momentum phase space. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB041 | |
| About • | paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 18 August 2021 | |
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| THPAB016 | Revisit of Nonlinear Dynamics in Hénon Map Using Square Matrix Method | 3788 |
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Funding: Work supported by the Accelerator Stewardship program, award number DE-SC0019403 with the U.S. Department of Energy Hénon map (2D or 4D) represents a thin lens sextupole in an otherwise linear lattice and had been well studied for many decades. We revisit the nonlinear properties of the Hénon map with the aid of the square matrix method and Arnold theorem, including acquiring the resonance structure and amplitude-dependent frequency. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB016 | |
| About • | paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 17 August 2021 | |
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