| Paper | Title | Page |
|---|---|---|
| TUPMF068 | Beam Dynamics on a Coupling Resonance at PETRA III | 1417 |
|
||
| Working on a coupling resonance is a usual way of producing round beams in a synchrotron. The beam dynamics in this regime is however more complicated, and the emittance is sensitive to the working point, coupling correction, and bunch current drop with time, which complicates the operation. We present experience with optics setup for working on a coupling resonance in PETRA III, including linear and nonlinear beam optics characteristics, and the measurement of the horizontal and vertical beam emittances with a 2D interferometer. Beam dynamics on a coupling resonance for PETRA IV, the MBA upgrade of PETRA III currently under consideration, is also presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF068 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| TUPMF072 | Microwave Instability and Energy Spread Measurement via Vertical Dispersion Bump in PETRA III | 1427 |
|
||
|
The recent measurement of bunch length versus current indicated that the longitudinal impedance (Z/n) is 0.15 Ω in close agreement with the impedance model*. Naive application of Keil-Schnell criteria predicts the threshold of microwave instability at 0.25 mA. Since the single bunch intensity is in the range of 0.2-2.5 mA depending on the fill-pattern of PETRA III, we expect to observe the fill-pattern dependent energy spread according to the theory. However, the 3rd generation light sources comparable to PETRA III often reported the observation which was much greater than the theoretical one. In order to induce the beam size variation we had used skew quadrupoles to generate the dispersion in vertical plane. In particular we made dispersion bump at the undulator sector so that we were able to use the X-ray optics for the precise determination of small vertical beam size. In this paper we report the experimental setup and measurement data with the estimate on the instability threshold. We also report the vertical emittance and energy spread based on the X-ray beam size measurement as well as the RF signal which was excited by the beam at the longitudinal feedback cavity.
* K. Balewski, R. Wanzenberg, "OBSERVATION OF INTENSITY DEPENDENT SINGLE BUNCH EFFECTS AT THE SYNCHROTRON LIGHT SOURCE PETRA III", Proc. of IPAC2011, p. 730. |
||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF072 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| TUPMF074 | Control of Collective Effects by Active Harmonic Cavity in an MBA-based Light Source with Application to the PETRA Upgrade | 1433 |
|
||
|
Based on the reference lattice for PETRA IV* we investigated collective effects with non-zero current. Out of many possibilities we firstly computed the intrabeam-scattering (IBS) effects on the emittance as well as lifetime as a function of current. The result indicated that PETRA IV would benefit from the reduced peak current when the harmonic cavity lengthens the bunch. The operating point of harmonic cavity was explored by tracking simulations as well as analytic formula. In order to compute the energy spread and bunch length we had used the known impedance function of the APS**. In this way more realistic estimation of IBS effects was expected. However, because of the complex nature of PETRA IV lattice, which includes achromatic cells for undulators, arc cells of octants and straight sectors for damping wigglers, we simplify the longitudinal dynamics by assuming the ring made of 92 multi-bend-achromat (MBA) cells. The optics is approximated as a linear-chromatic transfer map enabling fast tracking and the ring impedance is concatenated into the one location. The detailed collective effects with and without harmonic cavities are presented in the paper.
* J. Keil, "A PETRA IV Lattice Based on Hybrid Seven Bend Achromats", these proceedings. ** Y.-C. Chae and Y. Wang, "Impedance Database II for the Advanced Photon Source Storage Ring", Proc. PAC2007. |
||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF074 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| TUPMF083 | Influence of Intrabeam Scattering on the Emittance of PETRA III | 1463 |
|
||
| PETRA~III is a 6 GeV hard X-ray synchrotron radiation source at DESY in Hamburg (Germany) and is in user operation since~2010. The natural emittance of PETRA III is extremely low with 1.3 nm*rad and the coupling is typically less than 1%. PETRA III is operated with a beam current of 100 mA using two different filling modes: a continuous mode with 960 bunches and a timing mode with 40 bunches. It has been observed that the horizontal emittance depends on the filling pattern and is in timing mode slightly larger compared to the emittance in the continuous mode. Despite the high energy of 6 GeV intrabeam scattering contributes for a slight emittance growth due to the small natural emittance and coupling of the machine. The increase of the emittance as a function of the single bunch current has been measured by using different filling patterns at a fixed beam current of 100 mA. The measurements of the emittance and the lifetime as a function of the single bunch current will be compared with theoretical expectations of the emittance growth due to intrabeam scattering and the Touschek lifetime. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF083 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| TUPMF084 | Optimization of the Injection Kicker Bump Leakage at PETRA III | 1467 |
|
||
| PETRA III is a third generation synchrotron light source at DESY delivering high brightness photon beams for users at 21 beam lines. It is operated at 6 GeV with a beam current of 100 mA in top-up mode and is in operation for users since 2010. An off-axis injection scheme is used to accumulate beam from the booster synchrotron DESY II in PETRA III. Three fast injection kicker magnets generate a closed orbit bump for one turn to move the stored beam near to the injection septum magnet. Ideally the orbit bump generated by the 10 μs long half-sine pulses of the kickers should be closed. Due to differences in pulse shape as well as timing and amplitude errors of the pulses there is some leakage of the injection bump which disturbs the closed orbit and affects the beam quality during top-up operation. Turn-by-turn data from the beam position monitor (BPM) system of PETRA III have been used to measure the bump leakage for different bucket positions in the filling pattern. The procedure to reduce the injection kicker bump leakage and the achieved improvement will be discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF084 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| WEPAF044 | Automatic Tuning of PETRA, its Injector Complex, and Prospects of Autonomous Operation of PETRA IV | 1912 |
|
||
| We present the progress in tuning automation of the PETRA injection complex. The OCELOT optimizer has been ported to the PETRA control system and proof-of-principle tests of transmission efficiency optimization done. We further argue that the next steps in tuning and automation are impossible without rethinking the architecture of the high level contol system. A possible approach to the new system is then sketched. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF044 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| THPAF028 | Multi-Objectives Genetic Algorithms (MOGA) Optimization of PETRA IV Scenarios | 3015 |
|
||
| This paper reports the application of Multi-Objective Genetic Algorithms (MOGA) to optimize the linear and nonlinear beam dynamics of the different PETRA IV scenarios to transform PETRA III storage ring in a diffracted limited one. As it is well known, the dynamic aperture and momentum acceptance of these kinds of lattices are dramatically reduced due to the increase of the sextupoles strengths to compensate its strong focusing. The reduction of the dynamic aperture jeopardizes the current off-axis injection system and lower beam lifetimes increase the beam instabilities and the radiation safety concerns of the storage ring. MOGA searches the best settings of quadrupoles and sextupoles in a multi-dimensional parameter space taking into account the dynamic properties and the natural emittance as objectives at the level of ten picometers. The lattices studied are the so-called 'Twist lattice' based in a phase space exchange lattice, a solution based in the ESRF-Hybrid Multi-bend Achromat (HMA) design and finally the 'double 'I' lattice combining a non-interleaved sextupoles cell with an ESRF-HMA cell. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF028 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| THPAF030 | PETRA III Storage Ring Performance Improvement Based on Multi-Objective Genetic Algorithms (MOGA) | 3018 |
|
||
| The performance of the 3th generation light sources relies on the beam lifetime and the injection efficiency, both related with the beam dynamic properties of the storage ring as momentum acceptance and dynamic aperture, respectively. High values of beam lifetime and injection efficiency are desirable to reduce the storage ring instabilities during injection, the radiation losses and the energy consumption of the facility. This paper reports the first application of Multi-Objective Genetic Algorithms (MOGA) to optimize the linear and non-linear beam dynamics of PETRA III storage ring. Genetic algorithms are a heuristic search that mimics the process of natural evolution to optimize problems with a high level of complexity, as in the case of PETRA III storage ring composed by hundreds of magnets. This computational method uses hundreds of CPUs. MOGA is used to maximize the dynamic aperture and the momentum acceptance finding new combinations of quadrupole and sextupole settings in a multi-dimensional parameter space maintaining the solutions in the level of ten picometers. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF030 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| THPAF031 | A PETRA IV Lattice based on Hybrid Seven Bend Achromats | 3021 |
|
||
| For the PETRA IV project at DESY it is planned to convert the 6 GeV synchrotron light source PETRA III into a diffraction limited storage ring with ultra-low emittances. PETRA IV should provide a natural emittance two orders of magnitude smaller as now. The energy and the current of 100 mA should be unchanged. Currently different lattice options are investigated to achieve an emittance in the range of 10-30 pm*rad. As one candidate for a lattice of PETRA IV a ring based on the concept of hybrid multi-bend achromats (HMBA) has been studied in detail. Due to the unique layout of PETRA III with long straight sections it is possible to use damping wigglers to reduce the emittance further. While this helps to mitigate intrabeam scattering it has the disadvantage of an increased energy spread. The linear and nonlinear parameters of this HMBA-based lattice and the influence of damping wigglers on beam parameters are discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF031 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |