| Paper | Title | Page |
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| MOPGW029 | Preliminary Study of Bunch Compression in the Hefei Light Source | 151 |
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Funding: This work was supported by the Fundamental Research Funds for the Central Universities (Grant No.WK2310000082 and WK2310000077), and the National Natural Science Foundation of China(GrantNo.11475167). Short electron bunch has interesting applications in the synchrotron radiation light sources, such as the production of powerful coherent THz radiation, time resolving spectrum analysis, etc. In this work, we are interested in acquiring the short bunch in the storage ring with a small circumference like Hefei Light Source. In this paper, we tried to approach the short bunch in two separate methods: by increasing the higher harmonic cavity voltage and by reducing the momentum compaction factor. The preliminary result and observations are shown and discussed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW029 | |
| About • | paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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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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| TUPMP021 | Comparison of TiZrV Non-evaporable Getter Films Deposited by DC Magnetron Sputtering or Quantitative Deposition | 1283 |
| SUSPFO057 | use link to see paper's listing under its alternate paper code | |
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| Ti-Zr-V non-evaporable getter (NEG) films have been widely used in vacuum chambers of various accelerators since their discovery. Recently, we have used a new method called ’quantitative deposition’ to deposit Ti-Zr-V NEG films on nichrome substrates. The surface morphology and surface chemical bonding information were collected by scanning electron microscopy. Although the film deposited by DC magnetron sputtering has more uniform grain growth, smoother grain boundaries and higher porosity, the two films all have porous network structure and can be used as getter films. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP021 | |
| About • | paper received ※ 24 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP031 | Research on Secondary Electron Emission Characteristics of Diamond-like Carbon Thin Films | 1306 |
| SUSPFO081 | use link to see paper's listing under its alternate paper code | |
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| In modern particle accelerators, the build-up of electron cloud is a main limiting factor for the achievement of high-quality beam. Among the techniques to mitigate it, coating the internal walls of the beam pipes with a thin film which has a low secondary electron yield (SEY) is considered to be one of the most effective means. From several earlier studies, it was found that diamond-like carbon (DLC) thin films are potential coatings. This paper is mainly about the research on secondary electron emission characteristics of DLC thin films. The secondary electron emission (SEE) tests were done at temperature of 298 K and vacuum pressure of 2×10-9 Torr. Here, we obtained the characteristics of the SEE from DLC film coatings with different thickness under ultrahigh-vacuum (UHV) conditions. The maximum secondary electron yield (SEY), δmax, of the DLC thin films under different primary electron doses were also obtained, respectively. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP031 | |
| About • | paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPGW042 | Study of the Intra-beam Scattering Effects in the HALS Storage Ring | 1501 |
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Funding: This work was supported by the Fundamental Research Funds for the Central Universities (Grant No.WK2310000082 and WK2310000077). The Hefei Advanced Light Source (HALS) is designed to be a dedicated 4th generation diffraction limited light source. In 2018, the baseline lattice of the HALS storage ring has been proposed, with an ultra-low natural emittance of about 25 pm-rad. The preliminary study of intra-beam scattering effects on the beam emittance growth in the HALS storage ring has been performed with this baseline lattice. Due to the limited synchrotron radiation in this storage ring, damping wigglers are expected in this storage ring to reduce the damping time and reduce the emittance. In this paper, we will present the simulation results of the IBS effects, estimated effectiveness of damping wiggler and the corresponding linear optics calibration of the perturbation due to insertion device, and finally the estimated Touschek lifetime will be shown. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW042 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPGW056 | Comparison of Constrained Optimization Methods for Designing a Multi-Bend Achromat Lattice | 1535 |
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| In the design of a multi-bend achromat (MBA) lattice for a diffraction-limited storage ring, there are usually many magnet parameters to be optimized and some stringent constraints to be satisfied. For example, to cancel out nonlinear dynamics effects, the phase advances between some sections are generally required to be set to certain values in the lattice design. For better designing a MBA lattice using an evolutionary algorithm, the handling of constraints will be important, because it is very hard to satisfy the constraints for most or even all of solutions in the early generations of the algorithm. This paper will first describe some methods for handling constraints, which are then applied to designing a hybrid 7BA lattice. The comparison of these methods shows that better lattice solutions can be obtained by including constraints into objective functions. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW056 | |
| About • | paper received ※ 23 April 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019 | |
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| THPMP016 | Design of the Condenser System and Imaging System for a UEM | 3485 |
| SUSPFO054 | use link to see paper's listing under its alternate paper code | |
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| The ultrafast electron microscope provides a useful tool for exploring fine structure and observing dynamic process at nanometer and picosecond scale, which has been extensively applied in chemistry and biological field. After emitting from the electron gun, electron beams are focused on the stage sample by the condenser system and then be projected by the imaging system on the screen. In the present study, a two-lens condenser system is simulated by Parmela and a three-lens imaging system is designed using thin-lens approximation. Besides, the shape factor of metallic spheres which have different radius for perturbation method is measured, which is conductive to measuring the Z/Q parameter and the electric field along the axis of the C-band 3MeV photocathode gun for the UEM. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP016 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| THPTS045 | Preparation of Titanum-Zirconium-Vanadium Films by Quantitative Deposition | 4210 |
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| TiZrV has been used in vacuum technology and electric vacuum devices due to its high pumping speed and low activation temperature in recent years. At the same time, many preparation methods have been developed. Different from the current coating method of magnetron sputtering, this paper discusses the preparation of thin film coating from the viewpoint of vacuum sintering, which is flexible in design and more suitable for operation. Based on the analysis of the surface morphology of the sintered film, the feasibility and operability of the experimental method were explored from the surface compactness of the getter. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS045 | |
| About • | paper received ※ 25 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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