中国物理B ›› 2024, Vol. 33 ›› Issue (9): 95201-095201.doi: 10.1088/1674-1056/ad553a

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Exploration of microscopic physical processes of Z-pinch by a modified electrostatic direct implicit particle-in-cell algorithm

Kaixuan Li(李开轩), Cheng Ning(宁成)†, Ye Dong(董烨)‡, and Chuang Xue(薛创)   

  1. Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
  • 收稿日期:2024-04-25 修回日期:2024-05-26 接受日期:2024-06-07 发布日期:2024-08-15
  • 通讯作者: Cheng Ning, Ye Dong E-mail:ning_cheng@iapcm.ac.cn;dong_ye@iapcm.ac.cn
  • 基金资助:
    This research was partly supported by the National Natural Science Foundation of China (Grant Nos. 11675025 and 11135007), and the Innovation Project of China Academy of Engineering Physics (Grant No. CX2019030).

Exploration of microscopic physical processes of Z-pinch by a modified electrostatic direct implicit particle-in-cell algorithm

Kaixuan Li(李开轩), Cheng Ning(宁成)†, Ye Dong(董烨)‡, and Chuang Xue(薛创)   

  1. Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
  • Received:2024-04-25 Revised:2024-05-26 Accepted:2024-06-07 Published:2024-08-15
  • Contact: Cheng Ning, Ye Dong E-mail:ning_cheng@iapcm.ac.cn;dong_ye@iapcm.ac.cn
  • Supported by:
    This research was partly supported by the National Natural Science Foundation of China (Grant Nos. 11675025 and 11135007), and the Innovation Project of China Academy of Engineering Physics (Grant No. CX2019030).

摘要: For investigating efficiently the stagnation kinetic-process of Z-pinch, we develop a novel modified electrostatic implicit particle-in-cell algorithm in radial one-dimension for Z-pinch simulation in which a small-angle cumulative binary collision algorithm is used. In our algorithm, the electric field in $z$-direction is solved by a parallel electrode-plate model, the azimuthal magnetic field is obtained by Ampere's law, and the term for charged particle gyromotion is approximated by the cross product of the averaged velocity and magnetic field. In simulation results of 2 MA deuterium plasma shell Z-pinch, the mass-center implosion trajectory agrees generally with that obtained by one-dimensional MHD simulation, and the plasma current also closely aligns with the external current. The phase space diagrams and radial-velocity probability distributions of ions and electrons are obtained. The main kinetic characteristic of electron motion is thermal equilibrium and oscillation, which should be oscillated around the ions, while that of ion motion is implosion inwards. In the region of stagnation radius, the radial-velocity probability distribution of ions transits from the non-equilibrium to equilibrium state with the current increasing, while of electrons is basically the equilibrium state. When the initial ion density and current peak are not high enough, the ions may not reach their thermal equilibrium state through collisions even in its stagnation phase.

关键词: Z-pinch, particle-in-cell, ion heating, charged particle collisions

Abstract: For investigating efficiently the stagnation kinetic-process of Z-pinch, we develop a novel modified electrostatic implicit particle-in-cell algorithm in radial one-dimension for Z-pinch simulation in which a small-angle cumulative binary collision algorithm is used. In our algorithm, the electric field in $z$-direction is solved by a parallel electrode-plate model, the azimuthal magnetic field is obtained by Ampere's law, and the term for charged particle gyromotion is approximated by the cross product of the averaged velocity and magnetic field. In simulation results of 2 MA deuterium plasma shell Z-pinch, the mass-center implosion trajectory agrees generally with that obtained by one-dimensional MHD simulation, and the plasma current also closely aligns with the external current. The phase space diagrams and radial-velocity probability distributions of ions and electrons are obtained. The main kinetic characteristic of electron motion is thermal equilibrium and oscillation, which should be oscillated around the ions, while that of ion motion is implosion inwards. In the region of stagnation radius, the radial-velocity probability distribution of ions transits from the non-equilibrium to equilibrium state with the current increasing, while of electrons is basically the equilibrium state. When the initial ion density and current peak are not high enough, the ions may not reach their thermal equilibrium state through collisions even in its stagnation phase.

Key words: Z-pinch, particle-in-cell, ion heating, charged particle collisions

中图分类号:  (Z-pinches, plasma focus, and other pinch devices)

  • 52.58.Lq
52.65.Rr (Particle-in-cell method) 52.50.Sw (Plasma heating by microwaves; ECR, LH, collisional heating) 52.20.Hv (Atomic, molecular, ion, and heavy-particle collisions)