| Paper | Title | Page |
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| MOPGW044 | Off-Energy Off-Axis Injection with Pulsed Multipole Magnet Into the HALS Storage Ring | 187 |
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| As a future Diffraction-Limited Storage Ring (DLSR) at NSRL, the Hefei Advanced Light Source (HALS) has been proposed and has a great progress in the lattice optimization. The nonlinear dynamics is well designed and shows good performance, which makes it easier for beam injection and gives us more choices to design a more suitable injection scheme. In this paper, a new off-energy off-axis pulsed multipole injection scheme is proposed. The off-energy beam is off-axis injected into the acceptance of the storage ring with one or several pulsed multipole kickers and meanwhile the stored beam is almost unaffected during the injection. The injection acceptance of the storage ring is analyzed and the injection scheme is preliminary designed. A series of tracking simulations are carried out and the results are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW044 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019 | |
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| MOPGW045 | A Fast Method for Multi-Objective Nonlinear Dynamics Optimization of a Storage Ring | 190 |
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| Multi-objective evolutionary algorithms (MOEAs), including multi-objective genetic algorithm and particle swarm optimization algorithm, have been widely applied in the nonlinear dynamics optimization of storage ring light sources. In the optimization, the direct tracking of objectives, which are, for example, dynamic aperture (DA) and momentum aperture, is very time-consuming. We noticed that there is some positive correlation between on- and off-momentum nonlinear dynamics performances, which can be used to reduce the computation time when applying MOEAs. In this paper, a fast method is proposed, in which a strategy is introduced to speed up the process of optimizing nonlinear dynamics using MOEAs. Taking the SSRF storage ring as an example, on- and off-momentum DAs are optimized using MOEAs with and without the fast strategy, and then a comparison is made to demonstrate the fast method. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW045 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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| MOPGW115 | A Cross-Cell Interleaved Nonlinear Lattice for Potential NSLS-II Upgrade | 393 |
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| An interleaved sextupole scheme using cross-cell betatron phase cancellation technique is adopted as a candidate for the future NSLS-II upgrade lattice. The lattice uses as many NSLS-II installed magnets as possible, including 30 dipoles, to compose a triple bend achromat lattice. A 300 pm.rad horizontal beam emittance is achieved. The emittance can be further reduced to around 200 pm rad with damping wigglers. Various design concepts used in modern 4th-generation light sources, such as adopting longitudinal gradient dipoles and anti-bend scheme, are incorporated into the design as well. The betatron phase-advance between sextupoles is designed to have a cross-cell interleaving cancellation pattern in the transverse planes. The dynamic aperture is big enough for the conventional off-axis top-off injection. At the same time, a large energy acceptance looks promising to ensure a sufficiently long beam lifetime. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW115 | |
| About • | paper received ※ 12 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| MOPRB033 | Preliminary Research of HOM for 100MHz Superconducting Cavity in the Pre-Research Project of HALS | 649 |
| SUSPFO070 | use link to see paper's listing under its alternate paper code | |
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| A 100MHz QWR superconducting cavity is researched in the pre-research project of Hefei Advanced Light Source (HALS). Higher order modes (HOM) damping is a big challenge for synchrotron radiation light source. In this paper, we first apply the novel choke mode structure to the 100MHz QWR (quarter wave resonator) cavity in order to damp the HOM. We identify the main harmful higher order modes. The HOMs in the QWR cavity are suppressed by optimizing the choke dimensions. The broadband HOM impedance spectrum of the cavity was also evaluated by calculating the beam induced wake potential in time domain. The results show that choke mode structure has a good HOM damping effect on the QWR cavity. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB033 | |
| About • | paper received ※ 25 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP028 | Research Progress of Power Supply System in HALS | 1300 |
| SUSPFO068 | use link to see paper's listing under its alternate paper code | |
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Funding: Supported by ’the Fundamental Research Funds for the Central Universities’（WK2310000064） Supported by the Hefei Advanced Light Source Pre-research Project. Hefei Advanced Light Source (HALS) is the fourth generation light source in China’s planning and construction. In order to achieve the diffraction limit of the emission and improve the beam quality, the research on magnet power supply (MPS) technology is essential. We have designed a variety of solutions for different power supplies. We designed the first version of the high stability power supply control card. The first version of the high-stability power supply control card was designed and tested with a small power module. Our pre-research system has developed a corrector magnet power supply with a small signal response bandwidth higher than 10 kHz. The developed power prototypes all use self-developed controllers, and most of the test results can meet the requirements. This article describes the progress of the HALS power supply system. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP028 | |
| About • | paper received ※ 08 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPGW040 | Study of Seven-Bend Achromat Lattices with Interleaved Dispersion Bumps for HALS | 1495 |
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| Previously, we proposed a multi-bend achromat (MBA) lattice concept, called the MBA with interleav-ed dispersion bumps, which was then used to design a 7BA lattice for the Hefei Advanced Light Source (HALS) storage ring. Recently, such a 7BA lattice was further designed and optimized for the HALS by changing the number of lattice cells, scanning working point and employing octupoles. And two new HALS designs with such 7BA lattices have been made, one with 30 lattice cells and a natural emittance of 25 pm·rad and the other with 28 cells and 33 pm·rad. They had much better nonlinear dynamics perfor-mances than the previous design. The detailed study for these two HALS lattices will be presented in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW040 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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| TUPGW041 | Super-Period Locally Symmetric Lattices for Designing Diffraction-Limited Storage Rings | 1498 |
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| To achieve better nonlinear dynamics performance for a diffraction-limited storage ring, previously we proposed a locally symmetric multi-bend-achromat (MBA) lattice concept, where beta functions are locally symmetric about two mirror planes of each lattice cell. To have both high-beta long straight sections for beam injection and low-beta ones for higher brightness of insertion device radiation, many storage ring light sources use super-period lattices. The locally symmetric MBA lattice can be naturally extended to the super-period case. In the super-period locally symmetric (SP-LS) lattice, many nonlinear dynamics effects can be effectively cancelled out within one super-period lattice cell, and also there are many knobs to be used for further nonlinear optimization. As examples, two SP-LS lattices have been designed towards diffraction-limited emittances. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW041 | |
| About • | paper received ※ 20 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPGW054 | Design of a Hybrid Seven-Bend-Achromat Lattice for a High-Energy Diffraction-Limited Storage Ring Using a New Optimization Method | 1528 |
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| Recently, we proposed a new optimization method, with nonlinear dynamics indicators considered in the linear optics design, for designing hybrid multi-bend-achromat (MBA) lattices. With this method, two hybrid MBA lattices for medium-low-energy diffraction limited storage rings (DLSRs) have been designed, showing remarkable effectiveness in improving nonlinear dynamic performance. In this paper, we will apply this optimization method to the design of a hybrid 7BA lattice for a 6 GeV DLSR with the same circumference as that of HEPS. In the design, the strengths and arrangement of magnets of this lattice also meet the engineering requirement for HEPS. The designed lattice has a natural emittance of 34 pm·rad. The nonlinear dynamic performance is satisfactory, with a dynamic aperture of about 6 mm and 3 mm in the horizontal and vertical directions, respectively, and a dynamic momentum aperture of larger than 5%, which also shows the power of our optimization method. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW054 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPGW055 | Comparison of Optimization Methods for Hybrid Seven-Bend-Achromat Lattice Design | 1532 |
| SUSPFO079 | use link to see paper's listing under its alternate paper code | |
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| Generally, for a hybrid multi-bend-achromat (MBA) lattice with fixed linear optics, there is little potential to further optimize the nonlinear dynamics due to limited free knobs. To obtain a hybrid MBA lattice with better nonlinear dynamics performance, it is better to consider some indicators of nonlinear dynamics as objective functions in designing the linear optics using an optimization algorithm. In this paper, integral strengths of sextupoles and natural chromaticities are used as the nonlinear dynamics indicators, and different optimization methods with both or either of the two indicators are carried out and compared. As an example, a hybrid 7BA lattice with an energy of 2.4 GeV is designed towards an emittance of less than 70 pm·rad. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW055 | |
| About • | paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPGW057 | A Ten-Bend Achromat Lattice with Interleaved Dispersion Bumps for a Diffraction-Limited Storage Ring | 1538 |
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| Recently, a multi-bend achromat (MBA) lattice concept, called the MBA with interleaved dispersion bumps (IDB-MBA), was proposed to design the HALS storage ring, which presented better performance of both on- and off-momentum nonlinear dynamics. Since the beam emittance scales inversely with the third power of the number of bending magnets, in this paper we will study a new IDB-MBA lattice with more bending magnets. It is feasible to satisfy the requirement of the IDB-MBA concept in a 10BA lattice, and an IDB-10BA lattice is then designed for a storage ring light source with an energy of 2.4 GeV. The designed lattice has an ultra-low natural emittance of 81 pm·rad, and a dynamic aperture of about 6 mm and a large dynamic momentum aperture of 6% are achieved. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW057 | |
| About • | paper received ※ 24 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPRB045 | Stimulated Excitation by Seeding With Cherenkov Radiation in an Optical Cavity | 1785 |
| SUSPFO058 | use link to see paper's listing under its alternate paper code | |
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Funding: Work supported by National Foundation of Natural Sciences of China (11775216, 11705198, 11675178), and Fundamental Research Funds for the Central Universities (WK2310000061). By seeding with narrow-band Cherenkov radiation from a dielectric loaded waveguide(DLW), stimulated excitation in an optical cavity is presented. The evolution and energy loss of the field oscillating in optical cavity is analysed by the theoretical and numerical calculation. The results show that the high order TM modes of the Cherenkov radiation can be better preserved after a large number of roundtrips in the optical cavity and this scheme offers a potential method of realizing high power Terahertz radiation source in a compact facility. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB045 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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| THPTS046 | The Limited B-Field Integral of Superconducting Longitudinal Gradient Bend Magnet | 4213 |
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| The National Synchrotron Radiation Laboratory (NSRL) is planning a fourth generation diffraction-limited light source–Hefei Advanced Light Source (HALS), it is based on a seven-bend achromat lattice providing an ultralow natural emittance of 34 pm rad. The emittance can be even lower with the use of longitudinal gradient bends (LGBs) and anti-bends (ABs). The designed energy for HALS is 2.4 GeV, superconducting LGB might be employed instead of normal bending magnet since it can improve radiated beam critical energy to hard x-ray regions without using up any straight sections. To get a peak field about 6 T and small B-field profile full width half maximum, SLS-2 type LGB is considered. In this paper, the limited B-field integral (along the beam path) is trying to be find with some restrictions. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS046 | |
| About • | paper received ※ 12 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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