在太空中，由於電漿密度極低，其沿磁場方向壓力和垂直磁場方向壓力可以不相同。當沿磁場方向壓力大於垂直磁場方向壓力時會形成救火管不穩定現象。目前發現的救火管不穩定現象分為傳統救火管不穩定和最近由動力與磁流體模式中所發展的新型態救火管不穩定性。傳統的救火管不穩定性是不可壓縮的，且在沿磁場方向有最大的成長速率；而新型態的救火管不穩定性是可壓縮且最大成長速率發生在斜向傳播方向。過去對於研究救火管不穩定大多是基於動力理論及混合粒子碼數值模擬的方法。Wang and Hau [2003] 以壓力非均向之磁流體理論探討了新型態救火管不穩定之線性特徵與非線性演化的過程。
本論文採用壓力非均向之磁流體理論模式來研究沿磁場方向的傳統救火管不穩定性的非線性演化過程，並且探討霍爾電流項和電子壓力效應對傳統救火管不穩定的影響。由模擬結果可得知，霍爾電流項會抑制救火管不穩定性；均向的電子壓力則對於不穩定性的線性發展不造成影響；而非均向的電子壓力會提昇整體的壓力非均向性，使得不穩定性提早發生，且使磁場擾動值增大。

In collisionless space plasma pressure anisotropy may tend to occur. The fire-hose instability may arise when is sufficiently larger than where the subscripts and denote the component along and perpendicular to the background magnetic field, respectively. There exist two kinds of fire-hose instability: one is the classical Alfvén fire-hose mode, and the other is the new fire-hose mode. The classical fire-hose instability is incompressible and has maximum growth rate at parallel propagation; and the new fire-hose instability is compressible and has maximum growth rate at oblique propagation.
In this thesis we study the fire-hose instability in the MHD, Hall MHD and two-fluid models and examine how the electron temperature may affect the evolution of fire-hose instability. The study focuses on the parallel propagation case that involves only the classical fire-hose instability. The results from the Hall-MHD case show that the ion inertial terms may stabilize the instability and lead to propagating waves. While the anisotropic electron temperature may lead to larger magnetic field perturbations.

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雲上哲，離子慣性效應對救火管與磁鏡不穩定性之影響，碩士論文，國立中央大學太空科學研究所，2005。