人造衛星觀測資料顯示在太空電漿環境中，無碰撞電漿通常存在壓力非均向的特性，其熱力狀態非絕熱也不是等溫。本文中我們採用一組能包含雙絕熱及等溫的雙重多向性能量定律，並且考慮離子慣性效應，包括霍爾電流與電子溫度非均向性，來研究波長接近離子慣性長度的線性磁流體波的性質及其所伴隨的救火管不穩定性與磁鏡不穩定性發生之條件。一般而言，當電子溫度非均向性為 時，救火管不穩定性會受到增強而磁鏡不穩定性會受到抑制；反之，當電子溫度非均向性為 時，其結果會相反。甚至，電子溫度非均向性會使得原本穩定的磁流體波產生救火管與磁鏡不穩定性。 Satellite observations have revealed that the thermal pressure of collisionless plasmas usually exhibits the gyrotropic form with two distinct pressure components. Based on the double-polytropic magnetohydrodynamic (MHD) model, Hau and Sonnerup (1993) have found that the properties of MHD waves may greatly be modified by the pressure anisotropy. In this study, we extend the ideal double-polytropic MHD model to include the ion inertial terms arising from the Hall current as well the finite electron temperature for examining the properties of MHD waves. The dispersion relations are derived and the effects of the ion inertial terms on the fire-hose and mirror instabilities are examined. It is shown that for the electron temperature anisotropy of , the fire-hose instability is enhanced and the mirror instability is stabilized, but for the result is reverse. The originally stable MHD waves may even become unstable for sufficiently large electron temperature anisotropy.