博碩士論文 976403002 詳細資訊




以作者查詢圖書館館藏 以作者查詢臺灣博碩士 以作者查詢全國書目 勘誤回報 、線上人數:6 、訪客IP:18.218.172.249
姓名 李昆翰(Kun-Han Lee)  查詢紙本館藏   畢業系所 太空科學研究所
論文名稱 電子環射束產生之迴旋脈射不穩定性:電磁波的產生與電子加速
(Wave generation and electron acceleration associated with cyclotron maser instability driven by an electron ring-beam distribution in space plasmas)
相關論文
★ Fast Magnetosonic Shocks in the interplanetary Space and Magnetosphere★ Ring-beam粒子分布之電漿不穩定性模擬研究
★ 非對稱電流片磁重聯產生之不連續面與膨脹波★ 日冕洞與開放磁場區的特性與差異以及長期觀測
檔案 [Endnote RIS 格式]    [Bibtex 格式]    [相關文章]   [文章引用]   [完整記錄]   [館藏目錄]   [檢視]  [下載]
  1. 本電子論文使用權限為同意立即開放。
  2. 已達開放權限電子全文僅授權使用者為學術研究之目的,進行個人非營利性質之檢索、閱讀、列印。
  3. 請遵守中華民國著作權法之相關規定,切勿任意重製、散佈、改作、轉貼、播送,以免觸法。

摘要(中) 在太空電漿物理中,迴旋脈射不穩定性(cyclotron maser instability)是一項重要的無線電波輻射機制,尤其對太陽、行星及震波發射電波幅射,迴旋脈射更是重要的機制。其中著名的觀測現象例如地球極區千米波(auroral kilometric radiation),木星十米波(Jovian decametric radiation)。在迴旋脈射不穩定性中,有兩樣重要的因素,一是相對論效應下的波與粒子共振條件(resonance condition),另一個是居量反轉(population inversion)的粒子分布函數。若將前者表示為粒子速度的函數,將會是一個橢圓方程式;而後者對於迴旋脈射不穩定性的意義則是,在垂直磁場方向,高能粒子的速度空間分布密度大於低能量的粒子。根據這些特點,有許多特殊粒子分布函數能造成迴旋脈射不穩定性,例如損失錐(loss-cone)、環射束(ring-beam)、馬蹄形(horse-shoe)等分布函數。
本論文利用粒子模擬程式研究迴旋脈射不穩定性。初始條件中,我們考慮了背景電漿與相對低密度的環射束電子分布。模擬結果顯示,環射束電子中,平行磁場的電子速度分量在初期造成了雙流體不穩定性(two-stream instability),產生的電漿波與朗格繆爾(Langmuir)波和哨聲(whistler)波耦合。當雙流體不穩定性強度高時,初始電子分布很快地沿著水平磁場方向擴散至低能量區,使得後期才產生的脈射電漿波無法有效率地得到能量。相反的,當環射束電子中,垂直磁場的電子速度分量遠大於平行分量時,脈射不穩定性將能有效率地產生各種電漿波,包括X波、哨聲波和Z波,而O波雖然也有明顯的激發,但強度卻相對弱很多。
當電子環射束分布變成純環狀分布(pure ring distribution)時,模擬結果顯示平行磁場方向傳播的Z波與哨聲波能很有效率地加速電子。此加速機制主要是由波的相速度與振幅控制,而這些波的特性主要受電漿頻率與電子迴旋頻率比例的調控。電子加速的幅度最低約為兩倍,最高可達八倍,初始電子能量從100仟電子伏特到500仟電子伏特。我們進一步利用試驗粒子(test-particle)模式來研究此一加速機制。計算模型中,我們考慮電子與單獨一個或是兩個、四個同時存在的平面波相互作用。計算結果發現,若只有單獨一個平面波,則在速度空間中,電子僅沿著擴散曲線(diffusion curve)移動。若系統中存在著沿平行磁場方向而又反向傳播的波,電子加速可達到最大。
摘要(英) The cyclotron maser instability (CMI) is an important mechanism for radio emissions from the sun, astrophysical shocks and planets, such as solar radio bursts, auroral kilometric radiation (AKR) and Jovian decametric radiation (DAM). The key ingredients for CMI are (a) the relativistic effect in the resonance condition and (b) a population-inversion distribution providing free energy. The relativistic resonance condition yields an ellipse or hyperbola in the particle momentum space rather than a straight line with constant parallel momentum. A population inversion requires a positive gradient along the perpendicular momentum in the distribution function. According to these characteristics, there are several kinds of distribution that can support CMI, such as loss-cone, ring-beam and horse-shoe distributions.
In this thesis, we carry out a series of simulations to study CMI with an initial condition that a population of tenuous energetic electrons with a ring-beam distribution is present in a magnetized background plasma. The simulation results show that the beam component of the ring-beam distribution leads to the two-stream instability at an earlier stage, and the beam mode is coupled to the Langmuir and the whistler modes, leading to excitation of the beam-Langmuir and the beam-whistler waves, respectively. When the beam velocity is large and with a strong two-stream instability, the initial ring-beam distribution is diffused in the parallel direction rapidly, and the wave excitation associated with CMI at a later stage would become weak. On the contrary, when the beam velocity is small and the two-stream instability is weak, CMI can amplify the Z mode, the whistler mode or the X mode effectively while the O mode is relatively weak.
In the cases with a pure ring distribution, we further find strong acceleration of energetic electrons by the parallel Z-mode and the parallel whistler-mode waves generated by CMI. The electron acceleration is mainly determined by the wave amplitude and phase velocity, which in turn is affected by the ratio of electron plasma to cyclotron frequencies. For the initial kinetic energy ranging from 100 to 500 keV, the peak energy of the accelerated electrons is found to reach 2~8 times of the initial kinetic energy. We then study the acceleration process via test-particle calculations in which electrons interact with one, two or four waves. The electron trajectories in the one-wave case are simple diffusion curves. In the multi-wave cases, electrons are accelerated simultaneously by counter-propagating waves and can have a higher final energy.
關鍵字(中) ★ 電子環射束
★ 迴旋脈射不穩定性
★ 電子加速
關鍵字(英) ★ electron ring-beam distribution
★ cyclotron maser instability
★ electron acceleration
論文目次 摘要 i
Abstract ii
Acknowledgements iv
Table of contents v
List of Figures vii
List of Tables xvii
List of Symbols xviii
Chapter 1 Introduction 1
Chapter 2 Simulation model 12
2.1 Electromagnetic full particle simulation code 12
2.2 Initial electron ring-beam distribution and relevant parameters 18
Chapter 3 Generation of Z-, whistler-, X-, O- and Langmuir-mode waves 21
3.1 0.33 24
3.1.1 Case A1: 0.33, =1.2 (100keV) and =30 29
3.1.2 Case A2: 0.33, =1.4 (200keV) and =60 33
3.1.3 Case A3: 0.33, =1.2 (100keV) and =90 36
3.2 1 39
3.2.1 Case B1: 1.0, =1.2 (100keV) and =15 44
3.2.2 Case B2: 1.0, =1.2 (100keV) and =30 47
3.2.3 Case B3: 1.0, =1.2 (100keV) and =90 48
Chapter 4 Electron acceleration by the parallel Z- and the parallel whistler-mode waves 52
4.1 Waves associated with strong acceleration and diffusion 59
4.2 Test-particle calculations 65
4.2.1 Acceleration by a single wave 70
4.2.2 Two-wave resonant trapping 75
Chapter 5 Summary and Discussion 90
References 98
參考文獻 [1] Zarka, P., “The auroral radio emissions from planetary magnetospheres: What do we know, what don't we know, what do we learn from them?”, Adv. Space Res., Vol. 12, p.99, 1992
[2] Gurnett, D.A., "The earth as a radio source - terrestrial kilometric radiation", J. Geophys. Res., Vol. 79, p.4227, 1974.
[3] Wu, C.S., and L.C. Lee, "A theory of the terrestrial kilometric radiation", Astrophys. J., Vol. 230, p.621, 1979.
[4] Lee, L.C., and C.S. Wu, "Amplification of radiation near cyclotron frequency due to electron population inversion", Phys. Fluids, Vol. 23, p.1348, 1980.
[5] Freund, H.P., and C.S. Wu, "Induced gyroresonant emission of extraordinary mode radiation", Phys. Fluids, Vol. 20, p.619, 1977.
[6] Wagner, J.S., T. Tajima, L.C. Lee, and C.S. Wu, "Computer simulation of auroral kilometric radiation", Geophys. Res. Lett., Vol. 10, p.483, 1983.
[7] Wagner, J.S., L.C. Lee, C.S. Wu, and T. Tajima, "A simulation study of the loss cone driven cyclotron maser applied to auroral kilometric radiation", Radio Sci., Vol. 19, p.509, 1984.
[8] Pritchett, P.L., "Relativistic dispersion, the cyclotron maser instability, and auroral kilometric radiation", J. Geophys. Res., Vol. 89, p.8957, 1984.
[9] Pritchett, P.L., "Electron-cyclotron maser radiation from a relativistic loss-cone distribution", Phys. Fluids, Vol. 27, p.2393, 1984.
[10] Pritchett, P.L., "Relativistic dispersion and the generation of auroral kilometric radiation", Geophys. Res. Lett., Vol. 11, p.143, 1984.
[11] Pritchett, P.L., "Electron-cyclotron maser instability in relativistic plasmas", Phys. Fluids, Vol. 29, p.2919, 1986.
[12] Strangeway, R.J., "Wave dispersion and ray propagation in a weakly relativistic electron plasma: Implications for the generation of auroral kilometric radiation", J. Geophys. Res., Vol. 90, p.9675, 1985.
[13] Strangeway, R.J., "On the applicability of relativistic dispersion to auroral zone electron distributions", J. Geophys. Res., Vol. 91, p.3152, 1986.
[14] Freund, H.P., H.K. Wong, C.S. Wu, and M.J. Xu, "An electron cyclotron maser instability for astrophysical plasmas", Phys. Fluids, Vol. 26, p.2263, 1983.
[15] Wu, C.S., "A fast fermi process: Energetic electrons accelerated by a nearly perpendicular bow shock", J. Geophys. Res., Vol. 89, p.8857, 1984.
[16] Leroy, M.M., and A. Mangeney, "A theory of energization of solar wind electrons by the earth's bow shock", Ann. Geophys., Vol. 2, p.449, 1984.
[17] Wu, C.S., et al., "Generation of type III solar radio bursts in the low corona by direct amplification", Astrophys. J., Vol. 575, p.1094, 2002.
[18] Yoon, P.H., C.S. Wu, and C.B. Wang, "Generation of type III solar radio bursts in the low corona by direct amplification. II. further numerical study", Astrophys. J., Vol. 576, p.552, 2002.
[19] Kainer, S., et al., "Nonlinear wave interactions and evolution of a ring-beam distribution of energetic electrons", Phys. Fluids, Vol. 31, p.2238, 1988.
[20] Kainer, S., and R.J. MacDowall, "A ring beam mechanism for radio wave emission in the interplanetary medium", J. Geophys. Res., Vol. 101, p.495, 1996.
[21] Lee, K.H., Y. Omura, L.C. Lee, and C.S. Wu, "Nonlinear saturation of cyclotron maser instability associated with energetic ring-beam electrons", Phys. Rev. Lett., Vol. 103, p.105101, 2009.
[22] Wu, C.S., and H.P. Freund, "A kinetic cyclotron maser instability associated with a hollow beam of electrons", Radio Sci., Vol. 19, p.519, 1984.
[23] Wu, C.S., G.C. Zhou, and J. J. D. Gaffey, "Induced emission of radiation near 2ω by a synchrotron-maser instability", Phys. Fluids, Vol. 28, p.846, 1985.
[24] Wu, C.S., "Kinetic cyclotron and synchrotron maser instabilities: Radio emission processes by direct amplification of radiation", Space Sci. Rev., Vol. 41, p.215, 1985.
[25] Shi, B.R., J. J. D. Gaffey, and C.S. Wu, "Amplification of electromagnetic waves by a ring-beam distribution of moderately relativistic electrons", Phys. Fluids, Vol. 29, p.4212, 1986.
[26] Freund, H.P., J.Q. Dong, C.S. Wu, and L.C. Lee, "A cyclotron-maser instability associated with a nongyrotropic distribution", Phys. Fluids, Vol. 30, p.3106, 1987.
[27] Yoon, P.H., "Amplification of a high-frequency electromagnetic wave by a relativistic plasma", Phys. Fluids B, Vol. 2, p.867, 1990.
[28] Chen, Y.P., G.C. Zhou, P.H. Yoon, and C.S. Wu, "A beam-maser instability: Direct amplification of radiation", Phys. Plasmas, Vol. 9, p.2816, 2002.
[29] Yoon, P.H., C.B. Wang, and C.S. Wu, "Ring-beam driven maser instability for quasiperpendicular shocks", Phys. Plasmas, Vol. 14, p.022901, 2007.
[30] Wu, C.S., R.S. Steinolfson, and G.C. Zhou, "The synchrotron-maser theory of type II solar radio emission processes-the physical model and generation mechanism", Astrophys. J., Vol. 309, p.392, 1986.
[31] Farrell, W.M., "Direct generation of O-mode emission in a dense, warm plasma: Applications to interplanetary type II emissions and others in its class", J. Geophys. Res., Vol. 106, p.15701, 2001.
[32] Wu, C.S., et al., "On low-frequency type III solar radio bursts observed in interplanetary space", Astrophys. J., Vol. 605, p.503, 2004.
[33] Wu, C.S., et al., "Altitude-dependent emission of type III solar radio bursts", Astrophys. J., Vol. 621, p.1129, 2005.
[34] Benz, A.O., and G. Thejappa, "Radio emission of coronal shock waves", Astron. Astrophys., Vol. 202, p.267, 1988.
[35] Lee, K.H., Y. Omura, and L.C. Lee, "A 2D simulation study of langmuir, whistler, and cyclotron maser instabilities induced by an electron ring-beam distribution", Phys. Plasmas, Vol. 18, p.092110, 2011.
[36] Pritchett, P.L., et al., "Free energy sources and frequency bandwidth for the auroral kilometric radiation", J. Geophys. Res., Vol. 104, p.10317, 1999.
[37] Pritchett, P.L., R.J. Strangeway, R.E. Ergun, and C.W. Carlson, "Generation and propagation of cyclotron maser emissions in the finite auroral kilometric radiation source cavity", J. Geophys. Res., Vol. 107, p.1437, 2002.
[38] Lee, L.C., “Theories of non-thermal radiations from planets”, Plasma waves and instabilities at comets and in magnetospheres, American Geophysical Union, Washington, DC, 1989.
[39] Lee, L.C., J.R. Kan, and C.S. Wu, "Generation of auroral kilometric radiation and the structure of auroral acceleration region", Planet. Space Sci., Vol. 28, p.703, 1980.
[40] Winglee, R.M., and G.A. Dulk, "The electron-cyclotron maser instability as a source of plasma radiation", Astrophys. J., Vol. 307, p.808, 1986.
[41] Melrose, D.B., "Emission at cyclotron harmonics due to coalescence of z-mode waves", Astrophys. J., Vol. 380, p.256, 1991.
[42] Omura, Y., and D. Summers, "Dynamics of high-energy electrons interacting with whistler mode chorus emissions in the magnetosphere", J. Geophys. Res., Vol. 111, p.A09222, 2006.
[43] Omura, Y., N. Furuya, and D. Summers, "Relativistic turning acceleration of resonant electrons by coherent whistler mode waves in a dipole magnetic field", J. Geophys. Res., Vol. 112, p.A06236, 2007.
[44] Katoh, Y., and Y. Omura, "Relativistic particle acceleration in the process of whistler-mode chorus wave generation", Geophys. Res. Lett., Vol. 34, p.L13102, 2007.
[45] Katoh, Y., and Y. Omura, "Acceleration of relativistic electrons due to resonant scattering by whistler mode waves generated by temperature anisotropy in the inner magnetosphere", J. Geophys. Res., Vol. 109, p.A12214, 2004.
[46] Furuya, N., Y. Omura, and D. Summers, "Relativistic turning acceleration of radiation belt electrons by whistler mode chorus", J. Geophys. Res., Vol. 113, p.A04224, 2008.
[47] Hikishima, M., Y. Omura, and D. Summers, "Self-consistent particle simulation of whistler mode triggered emissions", J. Geophys. Res., Vol. 115, p.A12246, 2010.
[48] Omura, Y., and Q. Zhao, "Nonlinear pitch angle scattering of relativistic electrons by EMIC waves in the inner magnetosphere", J. Geophys. Res., Vol. 117, p.A08227, 2012.
[49] Summers, D., and Y. Omura, "Ultra-relativistic acceleration of electrons in planetary magnetospheres", Geophys. Res. Lett., Vol. 34, p.L24205, 2007.
[50] Su, Z., F. Xiao, H. Zheng, and S. Wang, "Radiation belt electron dynamics driven by adiabatic transport, radial diffusion, and wave-particle interactions", J. Geophys. Res., Vol. 116, p.A04205, 2011.
[51] Summers, D., B. Ni, and N.P. Meredith, "Magnetospheric physics-timescales for radiation belt electron acceleration and loss due to resonant wave-particle interactions: 2. evaluation for VLF chorus, ELF hiss, and electromagnetic", J. Geophys. Res., Vol. 112, p.A04207, 2007.
[52] Varotsou, A., et al., "Three-dimensional test simulations of the outer radiation belt electron dynamics including electron-chorus resonant interactions", J. Geophys. Res., Vol. 113, p.A12212, 2008.
[53] Lee, K.H., Y. Omura, and L.C. Lee, "Electron acceleration by Z-mode waves associated with cyclotron maser instability", Phys. Plasmas, Vol. 19, p.122902, 2012.
[54] Lee, K.H., Y. Omura, and L.C. Lee, " Electron acceleration by Z-mode and whistler-mode waves ", Phys. Plasmas, Vol. 20, p. 112901, 2013.
[55] Omura, Y., and H. Matsumoto, “KEMPO1: Technical guide to one-dimensional electromagnetic particle code”, Computer Space Plasma Physics: Simulation Techniques and Software, Terra Scientific, Tokyo, 1993.
[56] Omura, Y., “One-dimensional electromagnetic particle code: KEMPO1”, Advanced Methods for Space Simulations, Terra Sci., Tokyo, 2007.
[57] Umeda, T., Y. Omura, T. Tominaga, and H. Matsumoto, "A new charge conservation method in electromagnetic particle-in-cell simulations", Comput. Phys. Commun., Vol. 156, p.73, 2003.
[58] Jackson, J.D., Classical electrodynamics, 3rd ed., Wiley, New York, 1999, pp.531-532.
[59] Walker, A.D.M., Plasma waves in the magnetosphere, Springer-Verlag, New York, 1993.
[60] Summers, D., R.M. Thorne, and F. Xiao, "Relativistic theory of wave-particle resonant diffusion with application to electron acceleration in the magnetosphere", J. Geophys. Res., Vol. 103, p. 20487, 1998.
指導教授 李羅權、大村善治
(Lou-Chuang Lee、Yoshiharu Omura)
審核日期 2014-3-21
推文 facebook   plurk   twitter   funp   google   live   udn   HD   myshare   reddit   netvibes   friend   youpush   delicious   baidu   
網路書籤 Google bookmarks   del.icio.us   hemidemi   myshare   

若有論文相關問題,請聯絡國立中央大學圖書館推廣服務組 TEL:(03)422-7151轉57407,或E-mail聯絡  - 隱私權政策聲明