Two-dimensional simulation of dense plasma focus
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摘要: 为了探究稠密等离子体焦点装置内等离子体层的运动规律以及相关设计参数的影响，利用自主开发的FOI程序对Mather型放电室结构下的等离子体层加速过程、焦点形成过程进行二维磁流体力学仿真，得到了与美国Livermore国家实验室可见光实验图像相似的结果。同时，研究了装置的不同充气气压、电流幅值、阳极半径和阴阳极间隙对等离子体层轴向加速过程和箍缩效果的影响。计算结果表明，等离子体层会以一定的弧度沿径向压缩气体，这是引起腊肠不稳定现象的原因之一；等离子体层的轴向运动速度与装置充气压力的平方根成反比，与施加的电流成正比，与装置的阳极半径成反比；增大电流的同时需要延长装置阳极的长度，使箍缩发生在电流达到峰值的时刻；阴阳极间隙的大小对等阳极附近离子体层的轴向运动过程影响不大。Abstract: In order to investigate the motion law of the plasma sheath in a dense plasma focus (DPF) device and the influence of related design parameters, this paper uses a self-developed FOI program to conduct two-dimensional magnetohydrodynamic simulation of the plasma sheath motion process and focus formation process in the Mather type discharge chamber structure, and obtains results similar to the visible light experimental images of the Livermore National Laboratory in the United States. At the same time, the influence of different pressure, current, anode radius and cathode-anode gap on the motion law of the plasma sheath is explored. The calculation results show that the plasma sheath will compress the gas radially with a certain degree of curvature, which is one of the reasons for the instability phenomenon; the axial velocity of plasma sheath is inversely proportional to the square root of pressure, and is proportional to the current. The larger the anode size of the device, the smaller the axial velocity of sheath. To increase the current, it is necessary to extend the anode length to match the focusing time with the current peak. The gap between cathode and anode has little effect on the axial motion process of plasma sheath near the anode.
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Key words:
- dense plasma focus /
- magnetohydrodynamics /
- plasma sheath /
- pinch
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图 1 计算域边界条件示意图
Figure 1. schematic diagram of boundary conditions in computational domain
图 5 不同电流幅值对等离子体层轴向运动速度、箍缩时刻和压缩比的影响
Figure 5. influence of different current amplitudes on axial velocity of sheath, pinch time and compression ratio
图 7 阳极半径对箍缩时刻和压缩比的影响
Figure 7. effect of anode radius on pinch time and compression ratio
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[1] 郭洪生, 杨高照, 张建华, 等. 高强度、短脉冲中子源研制及其应用技术研究[C]//第三届全国核技术与应用学术研讨会会议资料文集. 2012: 95Guo Hongsheng, Yang Gaozhao, Zhang Jianhua, et al. Research on the development and application technology of high intensity and short pulse neutron sources[C]//The Third National Academic Symposium on Nuclear Technology and Applications. 2012: 95 [2] Mather J W. Formation of a high-density deuterium plasma focus[J]. Physics of Fluids, 1965, 8(2): 366-377. doi: 10.1063/1.1761231 [3] Filippov N V, Filippova T I, Vinogradov V P. Dense high-temperature plasma in a non-cylindrical Z-pinch compression[J]. Nuclear Fusion, 1962, S2: 577-587. [4] 郭洪生, 李恩平, 何锡钧, 等. 影响DPF焦点装置中子稳定性的因素和改进措施[J]. 原子核物理评论, 2004, 21(3):214-217 doi: 10.3969/j.issn.1007-4627.2004.03.008Guo Hongsheng, Li Enping, He Xijun, et al. Method of stability of neutron yields on denser plasma focus[J]. Nuclear Physics Review, 2004, 21(3): 214-217 doi: 10.3969/j.issn.1007-4627.2004.03.008 [5] 李名加, 范娟, 章法强, 等. 稠密等离子体焦点装置研制[J]. 强激光与粒子束, 2018, 30:115002 doi: 10.11884/HPLPB201830.180230Li Mingjia, Fan Juan, Zhang Faqiang, et al. Development of dense plasma focus device[J]. High Power Laser and Particle Beams, 2018, 30: 115002 doi: 10.11884/HPLPB201830.180230 [6] Hart P J. Plasma acceleration with coaxial electrodes[J]. The Physics of Fluids, 1962, 5(1): 38-47. doi: 10.1063/1.1706489 [7] Lee S. Plasma focus radiative model: Review of the Lee model code[J]. Journal of Fusion Energy, 2014, 33(4): 319-335. doi: 10.1007/s10894-014-9683-8 [8] Ay Y, Abd Al-Halim M A, Bourham M A. Simulation of the plasma sheath dynamics in a spherical plasma focus[J]. The European Physical Journal D, 2015, 69: 205. doi: 10.1140/epjd/e2015-60063-2 [9] Li Hui, Li Shengtai, Jungman G, et al. Dense plasma focus modeling[R]. Los Alamos: Los Alamos National Laboratory, 2017. [10] Jiang S, Higginson D P, Link A, et al. Effect of polarity on beam and plasma target formation in a dense plasma focus[J]. Physics of Plasmas, 2019, 26: 042702. doi: 10.1063/1.5048423 [11] Schmidt A, Anaya E, Anderson M, et al. First experiments and radiographs on the MegaJOuLe Neutron Imaging Radiography (MJOLNIR) dense plasma focus[J]. IEEE Transactions on Plasma Science, 2021, 49(11): 3299-3306. doi: 10.1109/TPS.2021.3106313 [12] Petkov E, Jackson S, Dasgupta A, et al. Characterization of electron beams from a dense plasma focus[J]. Bulletin of the American Physical Society, 2018, 63. [13] 段书超, 王刚华, 谢卫平, 等. FOI-PERFECT程序对电磁驱动高能量密度系统的三维弛豫磁流体力学模拟[J]. 强激光与粒子束, 2016, 28:045014 doi: 10.11884/HPLPB201628.125014Duan Shuchao, Wang Ganghua, Xie Weiping, et al. 3D relaxation MHD modeling with FOI-PERFECT code for electromagnetically driven HED systems[J]. High Power Laser and Particle Beams, 2016, 28: 045014 doi: 10.11884/HPLPB201628.125014 [14] Duan Shuchao, Kan Mingxian, Xiao Bo, et al. Numerical modelling of inverse wire array Z-pinch magnetic reconnection[J]. AIP Advances, 2018, 8: 055018. doi: 10.1063/1.5029323 [15] Duan Shuchao, Li Jing, Dan Jiakun, et al. A TVD implementation of constrained propagation for electromagnetic waves[J]. Advances and Applications in Fluid Mechanics, 2012, 12(2): 101-110. [16] Jin Shi, Xin Zhouping. The relaxation schemes for systems of conservation laws in arbitrary space dimensions[J]. Communications on Pure and Applied Mathematics, 1995, 48(3): 235-276. doi: 10.1002/cpa.3160480303 -
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