中国物理B ›› 2026, Vol. 35 ›› Issue (8): 85201-085201.doi: 10.1088/1674-1056/ae1567

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Theoretical analyses for influences of initial operating parameters on charged-particle transport characteristics in a low-pressure double-wall bounded decaying plasma

Yao-Ting Wang(汪耀庭), Xin-Li Sun(孙鑫礼), Lan-Yue Luo(罗岚月), Zi-Ming Zhang(张子明), He-Ping Li(李和平)†, Dong-Jun Jiang(姜东君), and Ming-Sheng Zhou(周明胜)   

  1. Department of Engineering Physics, Tsinghua University, Beijing 100084, China
  • 收稿日期:2025-07-30 修回日期:2025-09-23 接受日期:2025-10-21 发布日期:2026-08-06
  • 通讯作者: He-Ping Li E-mail:liheping@tsinghua.edu.cn
  • 基金资助:
    Project supported by the National Key Laboratory Fund form Particle Transport and Separation Technology (Grant No. WZKF-2024-2) and the National Natural Science Foundation of China (Grant No. 11775128).

Theoretical analyses for influences of initial operating parameters on charged-particle transport characteristics in a low-pressure double-wall bounded decaying plasma

Yao-Ting Wang(汪耀庭), Xin-Li Sun(孙鑫礼), Lan-Yue Luo(罗岚月), Zi-Ming Zhang(张子明), He-Ping Li(李和平)†, Dong-Jun Jiang(姜东君), and Ming-Sheng Zhou(周明胜)   

  1. Department of Engineering Physics, Tsinghua University, Beijing 100084, China
  • Received:2025-07-30 Revised:2025-09-23 Accepted:2025-10-21 Published:2026-08-06
  • Contact: He-Ping Li E-mail:liheping@tsinghua.edu.cn
  • Supported by:
    Project supported by the National Key Laboratory Fund form Particle Transport and Separation Technology (Grant No. WZKF-2024-2) and the National Natural Science Foundation of China (Grant No. 11775128).

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摘要： The influencing mechanisms of the initial operating parameters including the initial plasma density, electron temperature, plasma width, and externally applied voltage on ion extraction characteristics are studied based on a simplified one-dimensional analytical model for a double-wall bounded decaying plasma system. Firstly, a criterion of the dimensionless plasma width ($L_{\rm min}$) which is normalized with the Debye length for evaluating the state of the sheath expansion is proposed for the first time. Secondly, if the plasma width is larger than the value of $L_{\rm min}$, a complete sheath expansion process including both the supersonic and subsonic sheath expansion phases occurs during plasma decaying. Consequently, on the one hand, the total ion extraction time and the fraction of the extracted ions at the end of stage II, $i.e.$, the sheath expansion and ion rarefaction wave propagation stage during the whole ion extraction process, can be determined by the initial operating parameters; and on the other hand, it is estimated that about 70 % of ions can be extracted at the end of the second stage from the bulk plasma with a consumption of about 62.5 % of the total ion extraction time within the parameter ranges studied in this paper. This research is helpful for a deep understanding of the physical mechanisms of the charged-particle transport, as well as for guiding parameter optimizations with better ion extraction performances in practice.

关键词: ion extraction process, analytical model, parametric analyses

Abstract: The influencing mechanisms of the initial operating parameters including the initial plasma density, electron temperature, plasma width, and externally applied voltage on ion extraction characteristics are studied based on a simplified one-dimensional analytical model for a double-wall bounded decaying plasma system. Firstly, a criterion of the dimensionless plasma width ($L_{\rm min}$) which is normalized with the Debye length for evaluating the state of the sheath expansion is proposed for the first time. Secondly, if the plasma width is larger than the value of $L_{\rm min}$, a complete sheath expansion process including both the supersonic and subsonic sheath expansion phases occurs during plasma decaying. Consequently, on the one hand, the total ion extraction time and the fraction of the extracted ions at the end of stage II, $i.e.$, the sheath expansion and ion rarefaction wave propagation stage during the whole ion extraction process, can be determined by the initial operating parameters; and on the other hand, it is estimated that about 70 % of ions can be extracted at the end of the second stage from the bulk plasma with a consumption of about 62.5 % of the total ion extraction time within the parameter ranges studied in this paper. This research is helpful for a deep understanding of the physical mechanisms of the charged-particle transport, as well as for guiding parameter optimizations with better ion extraction performances in practice.

Key words: ion extraction process, analytical model, parametric analyses

中图分类号:  (Plasma dynamics and flow)

  • 52.30.-q
52.35.Fp (Electrostatic waves and oscillations (e.g., ion-acoustic waves)) 52.50.Qt (Plasma heating by radio-frequency fields; ICR, ICP, helicons) 28.60.+s (Isotope separation and enrichment)