| Paper |
Title |
Page |
| TUPC112 |
Equipment for Electrons Energy Measurement in HLS
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1326 |
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- H. Xu, G. Feng, B. Sun, L. Wang, J. F. Zhang, X. Zhao
USTC/NSRL, Hefei, Anhui
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The parameters necessary to dimension an equipment for the measurement of the beam energy of a storage ring via the resonance depolarisation are collected for HLS . The electron beam polarizes naturally due to the Sokolov-Ternv effect. For Hefei light source(HLS), the polarisation time is approx 4.346 h at 800MeV. The calculated value 4.346h is only for reference. The radial field will be applied to the beam by a pair of striplines mounted in the storage ring vacuum chamber. When input power is 12.5w, with OPRA program, intergrated field is calculated on axial. Different input power V. S integral field is also calculated. Which the depolarization time V. S input power can calculated by the below. The beam loss system for the electron storage ring of HLS can be used to measure the relative change of Touschek lifetime. It is expected that the relative change of Touschek lifetime due to beam depolarization will be measured in the future.
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| WEPC013 |
Commissioning of Medium Emittance Lattice of HLS Storage Ring
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2013 |
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- G. Feng, W. Li, L. Liu, L. Wang, H. Xu, S. C. Zhang
USTC/NSRL, Hefei, Anhui
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Hefei Light Source (HLS) is a second generation light source, whose emittance is about 160 nmrad in normal optics. Lowering beam emittance is the most effective measure to enhance light source brilliance. Considering beam lifetime limitation, a lattice with medium beam emittance was brought forward. Through distributed dispersion in straight section, the beam emittance was reduced to 80 nmrad. At same time, the betatron tunes were kept same as before. In this way, the focusing parameters can be tuned to new one smoothly. With the new lattice parameters, the brilliance of HLS is increased by two factors.
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| WEPC014 |
Beam Lifetime Studies of Hefei Advanced Light Source (HALS) Storage Ring
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2016 |
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- G. Feng, W. Li, L. Liu, L. Wang, C.-F. Wu, H. Xu, S. C. Zhang
USTC/NSRL, Hefei, Anhui
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Hefei Advanced Light Source (HALS) will be a high brightness light source with about 0.2nmrad emittance at 1.5GeV. Ultra low beam emittance and relatively low beam energy of HALS would result in poor beam lifetime. Comparing the beam-gas scattering and Touschek scattering effects, a conclusion can be drawn that Beam lifetime will be affected strongly by Touschek scattering. Touschek lifetime has been studied considering linear and nonlinear effects for the lattice structure. Relations between lifetime and RF cavity voltage, lifetime and emittance coupling, lifetime and gap heights of insertion devices have been calculated respectively. After the optimization, proper cavity voltage and emittance coupling are chosen to get about 1.06 hours of total lifetime including gas scattering losses effect. Installing a third harmonic RF cavity can lengthen the beam bunch to increase the total lifetime to about 3.85 hours. Top up injection operation will be applied to keep bunch current within the required value.
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| WEPC015 |
Baseline Design of HLS Linac Upgrade
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2019 |
| |
- G. Feng, W. Li, L. Shang, L. Wang, C.-F. Wu, H. Xu, S. C. Zhang
USTC/NSRL, Hefei, Anhui
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The existing 200MeV linac of Hefei Light Source (HLS) mainly consists of electron gun, prebuncher, buncher, one 3m S-band linac section, and four 6m S-band linac sections. Energy gain of electron beam at the end of the linac is 200MeV and energy spread is ±0.8%. In order to improve the electron beam quality, An upgrade project is required. Four 80MW klystrons will be used to instead the old ones, which can improve the beam energy stability. This upgrade can also make it possible to increase the linac energy from 200 MeV to 400 MeV without changing the accelerating structure. In the meantime, New operation modes of HLS linac has been found by extensive computer modelling and optimization. Electron beam dynamics simulation from electron gun to the end of linac has been given, which considering space charge effects and wakefields.
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| WEPC063 |
The Concept of Hefei Advanced Light Source (HALS)
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2136 |
| |
- L. Wang, G. Feng, W. Li, L. Liu, C.-F. Wu, H. Xu, S. C. Zhang
USTC/NSRL, Hefei, Anhui
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The Hefei Light Source is a dedicated VUV and soft X-ray light source. The layout of magnet lattice limits the achievalbe beam emittance and available straight section for insertion device. To enhance competitiveness of National Synchrotron Radiation Laboratory in synchrotron radiation application research region, a concept of new dedicated VUV and soft X-ray synchrotron radiation light source was put forward, which is named Hefei Advanced Light Source. Comparing the advantages, difficulties and performance/foundation of energy recovery linac, linac-based free electron laser and storage ring based light source, the scheme of a 1.5GeV storage ring with very low beam emittance was adopted as the baseline design. At same time, a low emittance 1.5 GeV linac would be as its full-energy injector, which can provide ultra-short radiation pulse. The HALS would provide more brilliant and transverse coherent synchrotron radiation in the VUV and soft X-ray range to various users.
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| WEPC064 |
The Possibility of Conversion of Hefei Light Source Storage Ring Into a Dedicated THz Radiation Source
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2139 |
| |
- L. Wang, G. Feng, W. Li, L. Liu, C.-F. Wu, H. Xu, S. C. Zhang
USTC/NSRL, Hefei, Anhui
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In the future of National Synchrotron Radiation Laboratory, a new advanced VUV and soft X-ray light source would be contructed and provide synchrotron radiation with high brilliance and transverse coherence. At that time, the current HLS storage ring would be replaced by the new one. Instead of retire of the old ring, there is another case, that is upgrading current low energy storage ring as a dedicated THz light source. In this paper, the possibility of lattice upgrading were evaluated. And its performance was estimated according to exist theoretical model.
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| WEPC065 |
The Lattice Design of Hefei Advanced Light Source (HALS) Storage Ring
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2142 |
| |
- L. Wang, G. Feng, W. Li, L. Liu, C.-F. Wu, H. Xu, S. C. Zhang
USTC/NSRL, Hefei, Anhui
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The purpose of Hefei Advanced Light Source is to provide high brilliant and coherent synchrotron radiation in the VUV and soft X-ray range to synchrotron radiation users. To enhance high brilliance and transverse coherent, very low beam emittance is required. The design goal of beam emittance is lower than 0.2 nmrad, whose synchrotron radiation is fully transverse coherent beyond the 2.5nm. Considering achievable undulator radiation spectrum and energy dependence of emittance, the energy of storage ring is set as 1.5GeV. Limiting the circumference of storage ring, the more dipole and strong focusing are needed for lowering emittance. On the other side, strong chromatic sextupoles are needed to compensate large natural chromaticity. The storage ring became strong nonlinear. The linear optics and nonlinear dynamics of HALS storage ring were introduced in this paper.
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| WEPC066 |
The Transport Line Upgrade Proposal of Hefei Light Source
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2145 |
| |
- L. Wang, G. Feng, W.-W. Gao, W. Li, L. Liu, H. Xu, S. C. Zhang
USTC/NSRL, Hefei, Anhui
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The injector of Hefei Light Source is a 200 MeV linac. A 55m transport line transfer beam to injection point of storage ring. At current stage, the mismatch of phase space is a potential source limiting the injection efficiency and stable operation of light source. A new focusing configuration of transport line was put forward, where the Twiss parameters matching was implemented. A skew quadrupole was introduced to make horizontal dispersion function matching. This matching between transport line and storage ring would be helpful to improve injection efficiency of HLS storage ring.
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| WEPP083 |
Development of an X-band Hybrid Dielectric-iris-loaded Accelerator
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2713 |
| |
- X. D. He, S. Dong, G. Feng, Y. J. Pei, C.-F. Wu
USTC/NSRL, Hefei, Anhui
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A compact x-band hybrid dielectric-iris-loaded travelling-wave linac with constant impendence structure has been designed. By adjusting the values of and the numbers of cells, the beam energy of 29 MeV, the capture efficiency about 50% and the energy spread about with the beam current being 70 mA and the electric gun voltage being 50KeV are obtained through longitudinal dynamics calculation. The length of accelerator tube is 1.12m . The maximum accelerating gradient is less than 45MV/m. By using electromagnetic code such as MAFIA, the attenuation per unit length of structure , the shunt impedance , the quality factor Q, the group velocity and the phase velocity are got by optimizing the dimensions of the cavities.
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| THPC044 |
Accurate Calculation of Higher Order Momentum Compaction Factor in a Small Ring
|
3074 |
| |
- L. Wang, G. Feng, W. Li, L. Liu, C.-F. Wu, H. Xu, S. C. Zhang
USTC/NSRL, Hefei, Anhui
|
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The key issues to obtain short beam bunch in storage ring is to lowering momentum compaction factor. When the linear momentum compaction factor is small, higher order momentum compaction factor can produce significant effects in the longitudinal beam dynamics. In the small storage ring, higher order momentum comaction factor is determined not only by sextupoles, and also by the fringe field of main magnets. In this paper, the higher order momentum factor formula including the effects of fringe field is deduced. As a example, the momentum compaction factor of HLS storage ring was calculated.
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