S波段HYBRID聚束-加速结构的样机研制

高斌; 裴士伦; 王辉; 赵世琦; 池云龙

doi:10.11884/HPLPB202133.200162

S波段HYBRID聚束-加速结构的样机研制

doi: 10.11884/HPLPB202133.200162

1.
清华大学工程物理系，北京 100084
2.
中国原子能科学研究院回旋加速器研究设计中心，北京 102413
3.
中国科学院高能物理研究所，北京 100049

基金项目: 国家自然科学基金项目（11475201）；中国科学院青年创新促进会基金项目

详细信息

作者简介:
高　斌（1990—），男，博士，从事直线加速器物理与微波技术研究；gaobin2019@126.com

中图分类号: TM931
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出版历程
- 收稿日期: 2020-06-12
- 修回日期: 2020-10-19
- 刊出日期: 2021-01-07

Development of S-band hybrid bunching-accelerating structure prototype

1.
Department of Engineering Physics, Tsinghua University, Beijing 100084, China
2.
Research and Design Center for Cyclotron, China Institute of Atomic Energy, Beijing 102413, China
3.
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China

摘要

摘要: Hybrid聚束-加速结构是把驻波预聚束器、行波聚束器和标准加速管集成到一起的新型RF结构。简述了对S波段Hybrid聚束-加速结构样机的束流动力学优化和微波设计结果，解释了Hybrid结构导致发射度增长的原因，对此样机进行了射频低功率测试。样机的冷测结果与RF设计结果一致性很好。在冷测频率2 855.21 MHz处，实测S₁₁小于−45 dB，腔间相移偏差小于±2°，VSWR≤1.2对应的带宽大于5 MHz，轴向场分布完全满足动力学要求。
- 聚束系统 /
- Hybrid聚束-加速结构 /
- 非谐振微扰法 /
- 反射相位法 /
- 低功率测试
Abstract: Hybrid bunching-accelerating structure (HBaS) is a novel RF structure integrating a standing-wave(SW) pre-buncher (PB), a traveling-wave (TW) buncher (B) and a standard accelerating structure together. This paper presents the design results, including beam dynamic optimization, microwave design and the cold test of the S-band HBaS prototype, and explicates the reason of transverse emittance increasement caused by the hybrid structure. The low RF power results are in good agreement with the RF design. The measured S₁₁ at operation frequency is less than −45 dB, the phase shift deviation is less than ±2° and the bandwidth is more than 5 MHz (VSWR≤1.2). The axis field distribution fully meets the dynamic requirements.
- bunching system /
- hybrid bunching-accelerating structure /
- non-resonant perturbation measurement /
- SLAC method /
- low power test

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图 1 采用Hybrid聚束-加速结构代替标准聚束系统示意图

Figure 1. Schematic of replacing the standard bunching system with the hybrid bunching-accelerating structure （HBaS）

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图 2 横向发射度增长曲线

Figure 2. Transverse emittance evolutions along the linac

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图 3 HBaS的SUPERFISH模型图

Figure 3. SUPERFISH model for the HBaS

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图 4 Hybrid聚束-加速结构机械设计模型

Figure 4. Mechanical design for the hybrid bunching-accelerating structure

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图 5 焊后Hybrid聚束-加速结构样机

Figure 5. Hybrid bunching-accelerating structure prototype after welding

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图 6 调配前Hybrid聚束-加速结构的整管微波特性

Figure 6. Bead-pull measurement results before tuning

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图 7 调谐后的测量结果

Figure 7. Bead-pull measurement results after tuning

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图 8 调谐前后局部反射系数

Figure 8. Local S_11，n before/after tuning

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表 1 加速单元排布方案

Table 1. β value for the accelerating cells

variant	β value for the cells in the SW section		$ {E}_{\rm{SW}}/{E}_{\rm{TW}} $	β value for the cells in the TW section
variant	SW1	SW2	$ {E}_{\rm{SW}}/{E}_{\rm{TW}} $	TW1	TW2	TW3	TW4	TW5	TW6	TW7	TW8
1	–	–	–	0.75	0.75	0.75	1	1	1	1	1
2	1.26	0.74	0.437	0.75	0.75	0.75	1	1	1	1	1
3	–	–	–	0.75	0.75	0.75	0.75	1	1	1	1
4	1.26	0.74	0.44	0.75	0.75	0.75	0.75	1	1	1	1
5	–	–	–	0.75	0.75	0.75	0.88	0.92	0.95	1	1
6	1.26	0.74	0.425	0.75	0.75	0.75	0.88	0.92	0.95	1	1

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表 2 动力学模拟结果

Table 2. Beam dynamic results for the bunching system

variant	capturing efficiency/%	${E}_{ {\rm{ave} }}$/MeV	trans efficiency/%	$ {E}_{{\rm{ave}}} $/MeV	trans efficiency/%	$ {E}_{{\rm{ave}}} $/MeV	$ \delta E $/MeV
variant	bunching system exit		chicane system exit		linac exit
1	78.9	11.1	51.4	11.8	51.4	101.2	±3.9
2	84.6	11.6	66.5	11.6	66.5	100.6	±4.0
3	83.7	10.9	70.4	11.2	70.4	94.8	±9.9
4	89.1	12.3	71.0	12.3	71.0	101.4	±3.9
5	81.6	11.2	70.4	11.5	70.4	95	±10.1
6	87.4	12.3	72.8	12.3	72.8	101.	±3.9

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表 3 Hybrid聚束-加速结构动力学要求

Table 3. Dynamic requirements for the HBaS

β values for the cells in the SW section		E_SW/E_TW	β values for the cells in the TW section
SW1	SW2	E_SW/E_TW	TW1	TW2	TW3	TW4	TW5	TW6	TW7	TW8～42
1.26	0.74	0.44	0.75	0.75	0.75	0.88	0.92	0.95	1	1

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