進階搜尋


下載電子全文  
系統識別號 U0026-2801201114044500
論文名稱(中文) 高密度螺旋電漿源內的密度不連續現象
論文名稱(英文) The Current-Free Double Layer in Helicon sources
校院名稱 成功大學
系所名稱(中) 太空天文與電漿科學研究所
系所名稱(英) Assistant, Institute of Space, Astrophysical and Plasma Sciences(ISAPS)
學年度 99
學期 1
出版年 100
研究生(中文) 蘇育正
研究生(英文) Yu-Jeng Su
學號 la697106
學位類別 碩士
語文別 英文
論文頁數 32頁
口試委員 指導教授-向克強
口試委員-陳秋榮
口試委員-河森榮一郎
中文關鍵字 電漿  螺旋電漿源  磁噴嘴  磁鏡 
英文關鍵字 double layer  helicon source  plasma propulsion  magnetic nozzle 
學科別分類
中文摘要 螺旋電漿源(helicon sources)擁有磁鏡般形狀的磁場。當電漿沿著磁力線流動時,這些磁場能夠扮演磁噴嘴(magnetic nozzle)的角色,並將磁噴嘴分為發散區(divergent side)、收斂區(convergent side)以及噴嘴頸(nozzle throat)。此外螺旋電漿源擁有強磁場、低氣壓以及高電漿密度的特性,這些特性是產生密度不連續現象(double layer)的必須條件。
密度不連續的現象在Charles以及Boswell的高密度螺旋電漿源實驗中被發現。他們發現密度、電漿位能以及溫度出現了非常急遽的變化。為了解釋這個現象,Ahedo以及Sa ́nchez發表了一套理論,考慮等溫(isothermal)系統裡面存在兩種不同溫度的電子分布。但是這套理論無法解釋實驗中所觀察到的溫度急遽變化的現象。為了解釋電子溫度的變化,等溫系統將不再適用。
在這篇論文裡面,我們提供了一套新的理論去解釋無碰撞電漿在磁噴嘴中的密度不連續現象。這套理論將結合冷離子、等溫的熱電子以及”幾乎”等溫的冷電子。這套理論可以計算出密度不連續現象的位置以及強度,並且可以決定冷電子溫度的變化強度。而我們所計算的溫度急遽變化強度符合實驗上所觀察到的結果。此外我們也發現電漿會被加速到超音速,且加速的主要來源是磁噴嘴結構的影響,急遽的位能變化對於電漿的加速是相當微小的。
英文摘要 Helicon sources can have mirror-like magnetic fields. These fields act like a magnetic nozzle that divides plasmas into the convergent side, the throat and the divergent side when plasmas flow along the field line. In addition, helicon sources, that have strong magnetic field, low gas pressure and high plasma density, provide the experimental setup for the current-free double layer.
In Charles and Boswell’s experiments [Appl. Phy. Lett. 82, 9 (2003)], a current-free double layer in high-density helicon discharges is observed. They have observed abrupt decreases in density and temperature across the double layer. To explain the experimental results, the physics of a current-free double layer in plasmas that have two components of isothermal electrons with different temperatures has been studied [Ahedo and Sa ́nchez, Phy. Rev. Lett. 130, 135002 (2009)]. However, this isothermal model cannot account for the change of the electron temperature across the double layer as seen in the experiments. To explain the abrupt change of the electron temperature, electrons cannot be isothermal along the magnetic field lines.
In this thesis, a model for the formation of a stationary current-free double layer in collisionless plasmas expanding in a magnetic nozzle is presented. The model consists of cold ions, isothermal hot electrons and fere-isothermal, i.e., almost isothermal, cold electrons and their dynamics. It can determine the position and the amplitude of double layer including the jump in cold electron temperature across the layer. The magnitude of the jump is consistent with the experimental observations. Plasmas are accelerated to the supersonic speed mainly by magnetic nozzle and the contribution from the double layer is small. The effects of ion charge Z on the flow speed at the nozzle throat and at the exit are also discussed.
論文目次 摘要 2
Abstract 3
致謝 4
Chapter 1 Introduction 6
1.1 Helicon sources 6
1.2 Helicon sources with current-free double layer 7
1.3 Plasma propulsions 9
Chapter 2 Current-free double layers 11
2.1 The history of current-free double layers 11
2.2 Double layer formation 12
2.2.1 The current-free double layer 13
Chapter 3 Theoretical model 15
3.1 The magnetic nozzle geometry 15
3.2 The quasineutral solutions 16
3.2.1 Electron dynamics in quasineutral region 17
3.2.2 Ion dynamics in quasineutral region 18
3.3 The plasma dynamics inside the double layer 23
3.3.1 Poisson equation and Sagdeev potential 23
3.3.2 Thermodynamic requirement 25
3.3.3 Results of the model 27
Chapter 4 Conclusions 29
Appendix Ambipolarity and quasineutrality 30
References 31

參考文獻 [1] R. Bowers, C. Legendy and F. Rose, Phys. Rev. Lett, 7, 9 (1961).
[2] Boswell R.W, Phys. Lett, 33A, 457 (1970).
[3] R. W. Boswell, Plasma Phys. Control. Fusion, 26, 10, 1147-1162 (1984).
[4] F. F. Chen, Laser and Particle Beams, 7, 3, 551-559 (1989).
[5] T. Shoji, Y. Sakawa, S. Nakazawa, K. Kadota and T. Sato, Plasma Sources Sci. Technol. 2, 5-10 (1993).
[6] Paul A. Keiter, Earl E. Scime and Matthew M. Balkey, Phys. Plasmas 4, 7 (1997).
[7] R. Boswell, R. Porteous, A. Prytz, A. Bouchoule and P. Ranson, Phys. Lett. A, 91, 4, 163-166 (1982).
[8] S. Shinohara, Jpn. J. Appl. Phys. 36, 4695-4703 (1997).
[9] S. Takechi, S. Shinohara and Y. Kawai, J. Appl. Phys. 36, 4558-4562 (1997).
[10] C. Charles and R. Boswell, Appl. Phys. Lett. 82, 9 (2003).
[11] B. Bezzerides, D. W. Forslund and E. L. Lindman, Phys. Fluids, 21, 12 (1978).
[12] Eric J. Lerner, Industrial Physicist, 16 (2000).
[13] Michael D. West, C. Charles and R. W. Boswell, Journal of Propulsion and Power, 24, 1 (2008).
[14] C. Charles and R. W. Boswell, Phys. Plasmas, 11, 4 (2004).
[15] S. A. Cohen, N. S. Siefert, S. Stange, R. F. Boivin, E. E. Scime and F. M. Levinton, Phys. Plasmas, 10, 6 (2003).
[16] X. Sun, C. Biloiu, R. Hardin and E. E. Scime, Plasma Sources Sci. Technol. 13, 359-370 (2004).
[17] F. W. Perkins and Y. C. Sun, Phys. Rev. Lett. 46, 2 (1981).
[18] L. P. Block, Astrophysics and Space Science, 55, 59-83 (1978).
[19] S. S. Hasan and D. T. Haar, Astrophys. Space Sci. 56, 89-107 (1978)..
[20] A. Meige, R. W. Boswell and C. Charles, Physics of Plasma, 12, 052317 (2005).
[21] M. A. Lieberman and C. Charles, Phys. Rev. Lett. 97, 045003 (2006).
[22] M. Manente, J. Carlsson, I. Musso, C. Bramati, D. Pavarin and F. Angrilli, American Institute of Aeronautics and Astronautics, 8, 11 (2007).
[23] S. Shinohara and K. P. Shamrai, Plasma Phys. Control. Fusion, 42, 865-880
[24] S. Ishiguro, T. kamimura and T. Sato, Phys. Fluids, 28, 7 (1985).
[25] F. F. Chen, Phys. Plasmas 13, 034502 (2006).
[26] E. Ahedo and M. M. Sánchez, Phys. Rev. Lett., 103, 135002 (2009).
[27] http://en.wikipedia.org/wiki/File:Double_layer_formation.png
[28] K. U. Riemann, Transaction on Plasma Sci. 23, 4 (1995).
[29] Ya. B. Zel’dovich and Yu. P. Raizer, Physics of Shock Waves and High Temperature Hydrodynamic Phenomena (Academic, New York, 1966), p. 67.
論文全文使用權限
  • 同意授權校內瀏覽/列印電子全文服務,於2012-01-31起公開。
  • 同意授權校外瀏覽/列印電子全文服務,於2013-01-31起公開。


  • 如您有疑問,請聯絡圖書館
    聯絡電話:(06)2757575#65773
    聯絡E-mail:etds@email.ncku.edu.tw