束内散射效应下HALF储存环物理参数的优化设计

罗楚文; 刘刚文; 李伟伟; 胡楠; 李为民; 白正贺; 王琳

doi:10.11884/HPLPB202234.220140

束内散射效应下HALF储存环物理参数的优化设计

doi: 10.11884/HPLPB202234.220140

中国科学技术大学国家同步辐射实验室，合肥 260029

基金项目: 国家重点研发计划项目（2016Y-FA0402000）；国家自然科学基金青年科学基金项目（12005226）；国家自然科学基金面上项目（11475167）

详细信息

作者简介:
罗楚文，lcw038@mail.ustc.edu.cn

通讯作者:
王　琳，wanglin@ustc.edu.cn

中图分类号: TL503
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- 文章访问数: 888
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- 被引次数: 0
出版历程
- 收稿日期: 2022-05-05
- 修回日期: 2022-06-19
- 网络出版日期: 2022-07-07
- 刊出日期: 2022-08-22

Parameters optimization considering intra-beam scattering in HALF lattice design

National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China

摘要

摘要: 合肥先进光源（HALF）是我国规划建设的软X射线与VUV衍射极限储存环光源（DLSR）。如何有效地实现衍射极限束流发射度，是DLSR物理设计中的核心问题之一。基于束流发射度演化方程，针对HALF预研项目的储存环物理设计方案，计算了束内散射（IBS）效应带来的发射度增长，研究了DLSR中关键参数选择对IBS造成的发射度增长的影响。研究表明，在中低能DLSR物理设计中需要综合考虑储存环的周长、同步辐射阻尼时间等关键参数，以更好地抑制束流发射度的增长。在此研究基础上，通过综合考虑用户需求与储存环物理要求，提出了HALF当前工程项目的储存环物理设计方案。进一步综合应用束团拉伸、全耦合等措施后，更高效地抑制了HALF储存环内IBS造成的束流发射度增长。
- 衍射极限储存环 /
- 合肥先进光源 /
- 亮度 /
- 束内散射 /
- 发射度增长
Abstract: Hefei Advanced Light Facility (HALF) is aimed to be a world-class diffraction limited storage ring (DLSR) in the soft X-ray & VUV regime. The characteristics and law of beam emittance evolution due to intra-beam scattering (IBS) in HALF storage ring was studied based on equations of equilibrium emittance. The results show that, it is necessary to comprehensively optimize the key parameters to obtain excellent beam performance in physical design of middle to low-energy DLSR. Applying the key parameters optimization strategy and taking methods to release the emittance growth due to IBS into consideration, the new version of HALF lattice can meet the needs of soft X-ray diffraction limit.
- diffraction-limited storage ring /
- Hefei Advanced Light Facility /
- brilliance /
- intra-beam scattering /
- emittance growth

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图 1 7BA储存环一个周期的磁聚焦结构及线性光学参数

Figure 1. Magnet layout and linear optical functions of one period 7BA lattice

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图 2 发射度及发射度增长率随自然发射度的变化

Figure 2. Change of emittance and emittance growth rate with natural emittance

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图 3 平衡发射度随同步辐射阻尼时间的变化

Figure 3. Equilibrium emittance vs SR damping time

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图 4 储存环周长参数的优化

Figure 4. Parameter optimization of storage ring circumference

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图 5 6BA储存环一个周期的磁聚焦结构及线性光学参数

Figure 5. Magnet layout and linear optical functions of one period 6BAlattice

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图 6 能散及水平方向平衡发射度随束流流强的变化

Figure 6. Change of energy spread and horizontal emittance with beam current

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表 1 7BA储存环主要设计参数

Table 1. Main parameters of the 7BA storage ring

parameter	value
beam energy	2.4 GeV
circumference	672 m
natural emittance	24.7 pm·rad
tune (H, V)	71.30, 23.30
natural chromaticity (H, V)	−97, −110
momentum compaction factor	5×10⁻⁵
natural energy spread	7.97×10⁻⁴
natural damping time (H, V, L)	(37.7,58.8,40.8) ms
energy loss per turn	182.9 keV
RF frequency	500 MHz

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表 2 HALF储存环IBS效应影响下平衡发射度

Table 2. Equilibrium emittance of the storage ring under IBS effects

$ \kappa /\mathrm{{\text{%}}} $	$ {\varepsilon }_{0} $/(pm·rad)	$ \mathrm{\varepsilon } $/(pm·rad)	$ {\sigma }_{\mathrm{p}0}/{10}^{-4} $	$ {\sigma }_{\mathrm{p}}/{10}^{-4} $	$ {\varepsilon }_{{x}0} $/(pm·rad)	$ {\varepsilon }_{{x}} $/(pm·rad)	$ ({\varepsilon }_{{x}}-{\varepsilon }_{{x}0})/{\varepsilon }_{{x}0} $
10	24.7	98.4	7.97	11.5	23.2	92.5	2.99
100	24.7	77.7	7.97	10.5	15.0	47.3	2.15

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表 3 6BA储存环主要设计参数

Table 3. Main parameters of the 6BA storage ring

parameter	value
beam energy	2.2 GeV
circumference	480 m
natural emittance	85.1 pm·rad
tune (H, V)	48.175,17.175
natural chromaticity (H, V)	−75, −59
momentum compaction factor	6.3×10⁻⁵
natural energy spread	6.6×10⁻⁴
damping time (H, V, L)	(22, 32.4, 21.2) ms
energy loss per turn	217.5 keV
RF frequency	500 MHz

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表 4 HALF储存环在IBS效应影响下平衡发射度

Table 4. Equilibrium emittance of the HALF storage ring under IBS effects

$ \kappa /\mathrm{{\text{%}}} $	$ {\varepsilon }_{0} $/(pm·rad)	$ \mathrm{\varepsilon } $/(pm·rad)	$ {\sigma }_{\mathrm{p}0}/{10}^{-4} $	$ {\sigma }_{\mathrm{p}}/{10}^{-4} $	$ {\varepsilon }_{x0} $/(pm·rad)	$ {\varepsilon }_{x} $/(pm·rad)	$ ({\varepsilon }_{x}-{\varepsilon }_{x0})/{\varepsilon }_{x0} $
10	85.1	185.4	6.6	9.19	79.6	173.4	1.178
100	85.1	153.4	6.6	8.35	50.2	90.5	0.803

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表 5 HALF储存环在IBS效应影响下平衡发射度

Table 5. Equilibrium emittance of the HALF storage ring under IBS effects

$ \kappa /\mathrm{{\text{%}}} $	$ {\varepsilon }_{0} $/(pm·rad)	$ \mathrm{\varepsilon } $/(pm·rad)	$ {\sigma }_{\mathrm{p}0}/{10}^{-4} $	$ {\sigma }_{\mathrm{p}}/{10}^{-4} $	$ {\varepsilon }_{x0} $/(pm·rad)	$ {\varepsilon }_{x} $/(pm·rad)	$ ({\varepsilon }_{x}-{\varepsilon }_{x0})/{\varepsilon }_{x0} $
10	84.2	129	6.94	7.98	78.5	120.3	0.53
100	84.2	110.5	6.94	7.56	48.6	63.8	0.31

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