Spreiter et al. (1966)由磁性流體力學理論以及守恆關係式，推導出當帶有超音速電漿的太陽風經過艏震波後，在沿日地連線上電漿會產生減速，分向，增溫的現象。透過守恆關係式可知，來自太陽風的壓力項，主要為動壓，在通過艏震波之後，電漿所具有的動壓項將會減弱，而轉換至磁壓項和熱壓項。在研究中，我們將使用ACE、 GEOTAIL、THEMIS 和WIND 衛星資料，以|Bx|/B > 0.9848 (X 方向為日地連線方向) 為條件，選取徑向行星際磁場事件，並取得事件中日地連線附近磁鞘衛星觀測時間區段資料，包括(1)艏震波後位置，(2)磁層頂前位置，以及(3)磁鞘中間區域時，計算動壓項、磁壓項和熱壓項，針對電漿熱壓項和磁壓項的比例關係，和太陽風參數與電漿壓力項變化之間的影響關係，進行分析討論，釐清在徑向行星際磁場環境下，各項影響參數對於磁鞘內壓力項轉換關係的影響程度，所得結果將可對影響磁鞘內壓力項轉換關係的因素有更進一步的了解。 Spreiter et al. (1966) simulated the behavior of supersonic solar-wind plasma passing through Earth’s magnetosphere from the gasdynamics. Their results show a deceleration, diversion and heating of plasma along the Sun-Earth line. The dynamic pressure, the dominant pressure term in solar wind, will reduce and transform into magnetic pressure and thermal pressure. In this proposed study, we will use magnetic fields from the ACE and Wind satellites to identify events of the radial interplanetary magnetic field under the criteria of |Bx|/B > 0.9848, where x is the direction along the Sun-Earth line. We will also use plasma and magnetic fields from THEMIS and Geotail to calculate all the pressure terms, including dynamic pressure, magnetic pressure, and thermal pressure for these events when the satellites are in the magnetosheath near the Sun-Earth line. We will focus on various magnetosheath regions: (1) right behind Earth’s bow shock, (2) right in front of Earth’s magnetopause, and (3) in the middle region of the magnetosheath. By analyzing the pressure-conversion relation and the ratio of thermal pressure to magnetic pressure, we can better understand conversion of solar wind energy in the magnetosheath for radial interplanetary magnetic fields. 研究期間：9908 ~ 10007
