| Paper |
Title |
Page |
| THPC024 |
Closed Orbit Correction at the LNLS UVX Storage Ring
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3029 |
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- L. Liu, R. H.A. Farias, X. R. Resende, P. F. Tavares
LNLS, Campinas
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The orbit correction of stored electrons in the LNLS storage ring often needs a few iterations to converge to the smallest distortion. This is caused in part by the residual coupling between transverse planes. This coupling effect can be included in the correction algorithm leading to the best orbit in just one iteration. However, in the LNLS ring, the number of monitors equals the number of vertical correctors but surpasses the number of horizontal correctors. This means that the vertical orbit can be corrected to zero at the position monitors in the decoupled situation but the horizontal orbit cannot. For the coupled case, the incapacity of zeroing the horizontal orbit leaks into the vertical plane. This problem can be addressed by the eigenvector method with constraints.
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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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| 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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| THPC044 |
Accurate Calculation of Higher Order Momentum Compaction Factor in a Small Ring
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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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| THPC138 |
Bunch-by-Bunch Online Diagnostics at HLS
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3309 |
| |
- J. H. Wang, Y. B. Chen, L. J. Huang, W. Li, L. Liu, M. Meng, B. Sun, L. Wang, Y. L. Yang, Z. R. Zhou
USTC/NSRL, Hefei, Anhui
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The design goal for the bunch-by-bunch analogue transverse feedback system at the Hefei Light Source (HLS) is to cure the transverse coupled bunch instabilities. The prototype implemented bunch-by-bunch feedback in 2006. Then we changed the circuit and replaced some components by ones of higher performance in order to get better effect. Diagnostic techniques are important tools to determine instabilities and to confirm the performance of the feedback systems. In addition to transverse feedback this system can provide online beam diagnostics and analysis in transverse and longitudinal directions. The diagnostic functions can record the response of every bunch while the feedback system manipulates the beam. The experimental results are presented.
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