微粒電漿中電漿微泡的生成與交互作用之動力行為研究

The formation and interactions of plasma bubbles in dusty plasma liquids

曲宏宇(Hong-Yu Chu)

指導教授 ： 伊林

國立中央大學/理學院/物理學系/博士(2006年)

摘要

氣泡在生活中處處可見，而不同產生的機制與其交互作用下的現象均為有趣及有挑戰性的研究話題。如脈衝雷射在水中產生氣泡的方式為一有趣的研究課題，其在雷射醫療中扮演極重要的作用方式。另外微粒電漿液體在近十年內被各國的研究團隊拿來作為模擬液體反應的 系統，如可研究脈衝波，固液體相變，及液體黏彈性的各種特性。故在此論文中試著以脈衝雷射在微粒電漿液體中產生電漿微泡作為研究課題。因微粒電漿為一非線性與多複雜性的系統，故在不同時間尺度下表現不同的動力行為。此論文中將對於不同時間尺度與不同背景壓力下做一系列的探討，包含於10-9~10-6 秒內脈衝雷射誘發微粒爆炸的膨脹行為，10-6~10-3 秒內周圍微粒的膨脹過程，10-3 後微粒空腔形成在不同壓力下由於離子與電子在電漿環境下表現各種不同現象。接著於論文內也討論了，電漿微泡與微粒波間的交互作用，以及微泡與微泡間不同方向性的交互作用。在本論文最後更討論以一方法引入微粒來量測在低壓力下的黏滯係數以及發現微粒庫倫電漿團下可改變電漿鞘的分佈情形。

關鍵字

電漿鞘 ； 電漿微泡 ； 雷射 ； 微粒電漿

並列摘要

Gas bubbles are observed in our daily life, which are generated through self-organization or external drives. One of the techniques generating bubble in liquid is through the vaporization of liquid by the intense laser pulse. It provides many applications in laser surgery and molecular and cellular biophysics.
On the other hand, the dusty plasma system is a weakly ionized plasma containing many micron-size dust particles. Through Coulomb interaction
and charging process, the massive dust grains are strongly coupled with the background plasma. It provides a platform to investigate the Mach
cone structure, the solid-liquid transition, viscoelastic property microscopically in the strongly coupled Coulomb liquid system. As the gas bubble generated in the liquid through the laser-liquid interaction, the plasma bubble can be generated in the dusty plasma liquid by the
intense laser pulse. It is found that the plasma bubble, a localized structure, sustains its shape and travels downward in the dusty plasma liquid. Hence, It brings out several interesting issues at different time scales. In this thesis,
the expansion of the spherical plume is compared with the shock wave model at nsec to ¹sec. The dust particles are pushed by the outward ion
flow associated with the plume and the plasma bubble is formed at usec to msec. After msec, the plasma bubble travels downward associated with a surrounding dipole-like dust flow field at suitable background condition. It is also found that there is a strong interaction between two vertically aligned plasma bubbles. The formation of the wave induced bubble suggests that the spherical void is an extreme case of the dust density wave with large amplitude. In the last part of this thesis, the observation of the dust cluster changing the sheath potential well is shortly discussed.

並列關鍵字

sheath ； plasma bubble ； dusty plasma ； laser

參考文獻

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