在宇宙射線和磁流波影響下的 電漿流之理論研究;A Theoretical Study of Outflows in the Presence of Cosmic Rays and Waves

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题名:	在宇宙射線和磁流波影響下的電漿流之理論研究;A Theoretical Study of Outflows in the Presence of Cosmic Rays and Waves
作者:	畢拉爾;Ramzan, Bilal
贡献者:	天文研究所
关键词:	流體力學;等離子體;宇宙射線;波浪;磁場;風;Hydrodynamics;Plasma;Cosmic rays;Waves;Magnetic field;Winds
日期:	2021-10-25
上传时间:	2021-12-07 11:18:03 (UTC+8)
出版者:	國立中央大學
摘要:	本論文從流體力學的理論觀點探討宇宙射線對在重力位井裡的電漿流或電漿風的影響。宇宙射線與在電漿裡的磁流擾動發生交互作用。在這個過程中，宇宙射線在電漿裡擴散和流動。除了熱電漿是流體外，在我們的模型中宇宙射線和自激性阿耳芬波也作流體處理。我們研究在位能井的基底有明確邊界條件下的「三流體」系統（含一個向前傳播的阿耳芬波）和「四流體」系統（同時含向前和向後傳播的阿耳芬波）中物理上允許的穩定態解。作為一個參照模型，一個沒有宇宙射線擴散也沒有波阻尼的「三流體」模型可以用如同處理經典帕克恆星風問題的方式研究。在考慮有宇宙射線擴散的情況下，我們發現有兩種類別的結果。一種是相似於沒有擴散的「三流體」模型，而另外一種則會發展成類似一般的純熱風，因為這個類別的波會消退繼而宇宙射線與熱電漿解耦不再有影響力。我們同時也探討冷卻效應對電漿流的效應。冷卻會造成亞音速純熱風失速，因此我們聚焦在亞音速─超音速過渡或是穿音速解。在相同的邊界條件下，我們比較有無冷卻效應和有無波阻尼的結果。;The impact of cosmic rays on plasma outflow or wind against a gravitational potential is studied theoretically from the perspective of hydrodynamics in this dissertation. Cosmic rays interact with hydromagnetic fluctuations embedded in plasma. In this process, cosmic rays diffuse and advect through the plasma. In addition to thermal plasma, cosmic rays and self-excited Alfv\′en waves are also considered as fluids in our model. We investigate physically allowable steady-state solutions for three-fluid system (with one forward propagating Alfv\′en wave) and four-fluid system (with both forward and backward propagating Alfv\′en waves) with certain boundary conditions at the base of the potential well. As a reference model, a three-fluid model without cosmic-ray diffusion and without wave damping can be studied in the same way as the classic Parker stellar wind problem. In the presence of cosmic-ray diffusion, we discovered two categories of solutions. One is similar to the three-fluid model without diffusion, while the other appears to behave like thermal wind when the waves die out and the cosmic rays become decoupled from the thermal plasma. We also examine the effect of cooling on the outflows. As cooling causes subsonic pure thermal outflow to stall, we focus on subsonic-supersonic transition or transonic solutions. We compare cases with/without cooling and with/without wave damping for the same set of boundary conditions.
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