Beamlet optics analysis of 400 keV accelerator for CRAFT negative ion based neutral beam injection system
-
摘要: 负离子源中性束注入（NNBI）系统是聚变堆主机关键系统综合研究设施（CRAFT）的组成部分，其目标是开展NNBI相关的科学与工程问题研究，为未来聚变堆NNBI系统的研制与运行积累经验。加速器的束流光学特性决定着最终形成束流的发散性，进而影响着束流在加速器和束线中的传输效率，这对NNBI系统的高功率、高能量、长脉冲运行至关重要。为此，采用IBSimu离子束流模拟程序对目前CRAFT NNBI的400 keV加速器电极系统的物理设计进行束流光学特性分析与评估。目前该套电极结构的设计与ITER负离子源类似，束发散的计算结果满足设计要求。在负离子束流密度较高时（100～300 A/m2范围内），具有更小束发散角；引出距离（5～7 mm范围内）和加速距离（88～110 mm范围内）的适当增加，也呈现出束发散角下降趋势。Abstract: The negative ion based neutral beam injection (NNBI) system is one of the testing or demonstrating systems in the frameworks of Comprehensive Research Facility of Fusion Technology (CRAFT). The object of the CRAFT NNBI system is to research the key physics and engineering issues around the NNBI, and to accumulate experience for future development and operation of the NNBI system for fusion reactor. The beamlet optics character of a negative ion accelerator determines the divergence of the formed beam, and further influences the beam transmission efficiency through the accelerator and the beamline, which is very important to the high-power, high-energy, and long-pulse operation of the NNBI system. Therefore, the ion beam simulation code IBSimu was used to analyze and estimate the physics design of the beamlet optics of the 400 keV accelerator for the CRAFT NNBI system. The IBSimu code has been successfully benchmarked and applied to many negative ion sources. The current design of the electrode aperture has a similar structure of the ITER negative ion source, the calculation results of the beamlet divergence can meet the design requirement. A higher extracted ion current density (between 100 to 300 A/m2) draws a lower beamlet divergence. When properly increasing the extraction gap (between 5 to 7 mm) or acceleration gap (between 88 to 110 mm), there is a decreasing tendency of the beamlet divergence.
-
图 1 IBSimu程序数值模拟的基本流程图
Figure 1. Basic flow chart of the numerical simulation with IBSimu code
图 3 CRAFT NNBI负离子源电极结构与电压关系
Figure 3. Aperture structure and voltage relation of the negative ion source for CRAFT NNBI
图 4 不同的离子电流密度的负离子（红色）和电子（黄色）引出与加速轨迹
Figure 4. Trajectories of negative ions (red line) and electrons (yellow line) during extraction and acceleration under different ion current densities
图 5 不同引出电流密度下，负离子束流在地电极出口处的发散角特性
Figure 5. Characteristics of the beamlet divergence at the GG aperture exit under different extracted current densities
图 6 不同模拟条件下，负离子束流在地电极出口处的发散角特性
Figure 6. Characteristics of the beamlet divergence at the GG aperture exit under different simulation conditions
图 7 不同的加速间距下，负离子束流在地电极出口处的发散角特性
Figure 7. Characteristics of the beamlet divergence at the GG aperture exit under different acceleration gaps
-
[1] Takeiri Y. Negative ion source development for fusion application (invited)[J]. Review of Scientific Instruments, 2010, 81: 02B114. doi: 10.1063/1.3274806 [2] Kashiwagi M, Hiratsuka J, Ichikawa M, et al. 100 s negative ion accelerations for the JT–60SA negative-ion-based neutral beam injector[J]. Nuclear Fusion, 2022, 62: 026025. doi: 10.1088/1741-4326/ac388a [3] Tsumori K, Ikeda K, Kisaki M, et al. Challenges toward improvement of deuterium-injection power in the Large Helical Device negative-ion-based NBIs[J]. Nuclear Fusion, 2022, 62: 056016. doi: 10.1088/1741-4326/ac2d59 [4] Hemsworth R S, Boilson D, Blatchford P, et al. Overview of the design of the ITER heating neutral beam injectors[J]. New Journal of Physics, 2017, 19: 025005. doi: 10.1088/1367-2630/19/2/025005 [5] Xie Yanghong, Hu Chundong, Wei Jianglong, et al. Conceptual design of a beam source for negative neutral beam injector of CRAFT facility[J]. Fusion Engineering and Design, 2021, 167: 112377. doi: 10.1016/j.fusengdes.2021.112377 [6] Bacal M, Wada M. Negative hydrogen ion production mechanisms[J]. Applied Physics Reviews, 2015, 2: 021305. doi: 10.1063/1.4921298 [7] Wei Jianglong, Hu Chundong, Xie Yahong, et al. Physics and engineering design of 400 keV H– accelerator for negative ion based neutral beam injection system in China[J]. Review of Scientific Instruments, 2019, 90: 113313. doi: 10.1063/1.5128335 [8] Wei Jianglong, Yang Yuwen, Gu Yuming, et al. An integration design model for a large-scale negative ion accelerator of neutral beam injection system for fusion application[J]. Physics of Plasmas, 2023, 30: 033102. doi: 10.1063/5.0139827 [9] Brown I G. The physics and technology of ion sources[M]. 2nd ed. Weinhein, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2004. [10] Pamela J. A model for negative ion extraction and comparison of negative ion optics calculations to experimental results[J]. Review of Scientific Instruments, 1991, 62(5): 1163-1172. doi: 10.1063/1.1141995 [11] Becker R. NIGUN: A two-dimensional simulation program for the extraction of H− ions[J]. Review of Scientific Instruments, 2004, 75(5): 1723-1725. doi: 10.1063/1.1695610 [12] Kalvas T, Tarvainen O, Ropponen T, et al. IBSIMU: a three-dimensional simulation software for charged particle optics[J]. Review of Scientific Instruments, 2010, 81: 02B703. doi: 10.1063/1.3258608 [13] 王惠三, 简广德, 周才品. 高能强流负离子束系统束光学特性的数值模拟[J]. 核聚变与等离子体物理, 2000, 20(2):93-99 doi: 10.3969/j.issn.0254-6086.2000.02.005Wang Huisan, Jian Guangde, Zhou Caipin. Numerical simulation of the beam optics characteristics in a high energy and high current negative ion beam system[J]. Nuclear Fusion and Plasma Physics, 2000, 20(2): 93-99 doi: 10.3969/j.issn.0254-6086.2000.02.005 [14] De Esch H P L, Kashiwagi M, Taniguchi M, et al. Physics design of the HNB accelerator for ITER[J]. Nuclear Fusion, 2015, 55: 096001. doi: 10.1088/0029-5515/55/9/096001 [15] Agostinetti P, Aprile D, Antoni V, et al. Detailed design optimization of the MITICA negative ion accelerator in view of the ITER NBI[J]. Nuclear Fusion, 2016, 56: 016015. doi: 10.1088/0029-5515/56/1/016015 [16] Wimmer C, Schiesko L, Fantz U. Investigation of the boundary layer during the transition from volume to surface dominated H− production at the BATMAN test facility[J]. Review of Scientific Instruments, 2016, 87: 02B310. doi: 10.1063/1.4932985 [17] Kisaki M, Tsumori K, Ikeda K, et al. Characteristics of plasma grid bias in large-scaled negative ion source[J]. Review of Scientific Instruments, 2014, 85: 02B131. doi: 10.1063/1.4854295 [18] Kojima A, Hanada M, Tanaka Y, et al. Achievement of 500 keV negative ion beam acceleration on JT-60U negative-ion-based neutral beam injector[J]. Nuclear Fusion, 2011, 51: 083049. doi: 10.1088/0029-5515/51/8/083049 -
下载:
点击查看大图
计量
- 文章访问数: 358
- HTML全文浏览量: 116
- PDF下载量: 58
- 被引次数: 0
