射频栅控电子枪的仿真分析及优化设计

王钰杰; 何小中; 秦臻; 唐若

doi:10.11884/HPLPB202537.250020

射频栅控电子枪的仿真分析及优化设计

doi: 10.11884/HPLPB202537.250020

中国工程物理研究院流体物理研究所，四川绵阳 621900

详细信息

作者简介:
王钰杰，1220602107@qq.com

通讯作者:
何小中，hexiaozhong@tsinghua.org。

中图分类号: O463+.1
计量
- 文章访问数: 25
- HTML全文浏览量: 10
- PDF下载量: 2
- 被引次数: 0
出版历程
- 收稿日期: 2025-01-15
- 修回日期: 2025-06-08
- 录用日期: 2025-06-10
- 网络出版日期: 2025-06-23

Simulation analysis and optimization design of RF grid-controlled electron gun

Institute of Fluid Physics, CAEP, Mianyang 621900, China

摘要

摘要: 加速器的束流品质直接影响着其应用性能，电子枪的结构决定了加速器的初始束流状态。优化针对花瓣加速器所适用的射频栅控电子枪，减小其发射度可得到更高的CT成像分辨率。模拟分析基于CST的Particle Tracking求解器得到了归一化发射度0.4918 mm·mrad、峰值流强35 mA的束流，并且讨论了电子枪结构改变对电子枪发射度以及TWISS参数的影响。结果表明，当聚焦极角度改变时对归一化发射度具有较大影响，且在67.5°、60°和45°中，60°度的归一化发射度最小为0.2617 mm·mrad。
- 花瓣加速器 /
- 电子枪 /
- 栅控 /
- 发射度
Abstract: The beam quality of the accelerator directly affects its application performance, and the structure of the electron gun determines the initial beam state of the accelerator. Optimizing the RF grid-controlled electron gun suitable for rhodotron and reducing its emittance can obtain higher CT imaging resolution. The Particle Tracking solver based on CST is simulated and analyzed to obtain a beam with a normalized rms emittance of 0.4918 mm·mrad and a peak current of 35 mA. And discussed the influence of changes in electron gun structure on the emittance of and TWISS parameters.The results show that when the focus Angle changes, the normalized rms emittance is greatly affected. And in 67.5°, 60° and 45°, the minimum normalized rms emittance is 0.2617 mm·mrad when the focus Angle is 60°.
- rhodotron /
- electron gun /
- grid-controlled /
- emittance

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图 1 I型栅网

Figure 1. Type-I grid

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图 2 电子枪及漂移段内归一化RMS发射度的分布

Figure 2. Normalized RMS emittance distribution in electron gun and drift section

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图 3 电子枪的结构图

Figure 3. Structure of the electron gun

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图 4 不同相位粒子阴栅渡越时间分布

Figure 4. Distribution of transit time of particles in different phases

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图 5 一个束团周期在阳极处的电流信号

Figure 5. Current signal of a periodric cluster at the anode

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图 6 不同栅网结构的横截面图

Figure 6. Cross-sectional diagrams of different grid structures

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图 7 不同的栅网结构对应的归一化RMS发射度在电子枪内的纵向分布

Figure 7. Longitudinal distribution of the normalized RMS emittance in the electron gun corresponding to different grid structures

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图 8 不同角度聚焦极结构的剖面图

Figure 8. Sectional views of different focal stage structures

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图 9 不同的聚焦极角度对应的归一化发射度纵向分布

Figure 9. Longitudinal distribution of the normalized RMS emittance in the electron gun corresponding to different focusing electrode angles

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表 1 式（13）与CST模拟结果的部分验证

Table 1. Partial verification of Equation (13) and CST simulation results

radius/mm	phase/(°)	geometric RMS emmittance (simulation)/(mm·mrad)	geometric RMS emmittance (fomula)/(mm·mrad)
1.500	11.0	59.31	59.19
0.645	13.5	31.41	31.38
0.645	21.5	50.92	50.90

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表 2 各相位粒子的结果

Table 2. Results of particles in each phase

phase/(°)	grid voltage/V	anode simulated current/mA	cathode simulated current/mA	transmittance/%	nomalized RMS emmtiance/(mm·mrad)
36	26.336	19.074	25.361	0.752 100	2.880
42	50.739	42.085	58.219	0.722 874	2.190
48	72.943	67.050	94.741	0.707 719	1.680
54	92.705	92.069	131.775	0.698 683	1.300
60	109.808	115.547	166.887	0.692 367	1.070
66	124.064	144.451	210.475	0.686 310	0.828
72	135.317	160.944	235.677	0.682 901	0.681
78	143.444	174.412	256.316	0.680 457	0.613
84	148.357	183.429	270.134	0.679 030	0.576
90	150.000	186.040	274.511	0.677 714	0.569
96	148.357	183.429	270.134	0.679 030	0.576
102	143.444	174.412	256.316	0.680 457	0.613
108	135.317	160.944	235.677	0.682 901	0.681
114	124.064	144.451	210.475	0.686 310	0.828
120	109.808	115.547	166.887	0.692 367	1.070
126	92.705	92.069	131.775	0.698 683	1.300
132	72.943	67.05	94.741	0.707 719	1.680
138	50.739	42.085	58.219	0.722 874	2.190
144	26.336	19.074	25.361	0.752 100	2.880

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表 3 各相位粒子的结果

Table 3. Results of particles in each Phase

phase/(°)	grid voltage/V	anode theoretical current/mA	anode simulated current/mA	cathode simulated current/mA	transmittance/%	nomalized RMS emmtiance/(mm·mrad)
36	26.336	2.590	3.915	4.984	0.785 514	1.200
42	50.739	6.927	8.149	11.640	0.700 086	0.940
48	72.943	11.940	13.211	19.100	0.691 675	0.756
54	92.705	17.107	18.32	26.684	0.686 554	0.621
60	109.808	22.053	23.138	33.888	0.682 779	0.521
66	124.064	26.484	27.403	40.313	0.679 756	0.482
72	135.317	30.168	30.926	45.639	0.677 622	0.436
78	143.444	32.926	33.553	49.619	0.676 213	0.384
84	148.357	34.632	35.173	52.077	0.675 404	0.351
90	150.000	35.209	35.27	56.390	0.625 466	0.321
96	148.357	34.632	35.173	52.077	0.675 404	0.351
102	143.444	32.926	33.553	49.619	0.676 213	0.384
108	135.317	30.168	30.926	45.639	0.677 622	0.436
114	124.064	26.484	27.403	40.313	0.679 756	0.482
120	109.808	22.053	23.138	33.888	0.682 779	0.521
126	92.705	17.107	18.320	26.684	0.686 554	0.621
132	72.943	11.940	13.211	19.100	0.691 675	0.756
138	50.739	6.927	8.149	11.640	0.700 086	0.940
144	26.336	2.590	3.915	4.984	0.785 514	1.200

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表 4 不同聚焦角度对阳极出口处归一化RMS发射度及TWISS参数的影响

Table 4. Effects of different focusing angles on the normalized RMS emittance and TWISS parameters at the anode outlet

	${\varepsilon _{{\mathrm{n}},{\mathrm{RMS}}}} $/(mm·mrad)	α	β/m	γ/m⁻¹
67.5°	0.4918	−0.9757	0.08205	23.8
60°	0.2617	−0.4925	0.01403	88.5
45°	0.2732	−0.1349	0.01302	78.2

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