摘要 本文利用中華衛星一號上的電離層電漿及電動效應儀 (IPEI) 在2000年所收集到的相關資料，研究頂部電離層重離子(主要是NO+)含量異常的分布與發生機制。西元2000年正值太陽黑子活動最大期。IPEI所觀測到的重離子分布約可歸納為兩類。第一類是在地磁活動寧靜期所觀測到存在於磁赤道附近的O+離子密度極低區。這些重離子可能是電漿泡自底部快速上升到頂部電離層來。第二類是在巨型磁暴發生期衛星所觀測到的，比在地磁活動寧靜期大得很多，且在地理位置的分布上也較為寬廣，且常偏離磁赤道甚遠。這些重離子除了可能是上升的電漿泡外，也可能是由高緯度極光區所產生的重離子擾動傳播到低緯度區。進一步分析高解析度(1024Hz)的離子密度及速度變化，我們發現重離子含量異常區的波譜特性有別於離子成分含百分百O+的電離層區。隨著NO+及O+比值的增加，在波長(100公尺到10公尺)範圍的功譜密度(P)隨波數(k)的變化不再遵循 的關係式。離子成份如何影響電漿的不規則體結構，雖然不在本篇論文裡探討，卻是另一個值得更深入研究的課題。 Abstract Data from the IPEI payload onboard ROCSAT-1 are used to study the phenomena of the anomalous increase of heavy ions (mainly NO+) in the topside ionosphere for the solar maximum period of Year 2000. We separated the distribution of heavy ions into two different types. One type is that the heavy ions were observed in the O+ depleted region near the dip equator during the geomagnetic quiet time. Such heavy ions are part of the fast rising bubbles that originated from the bottomside ionosphere. The other type is the heavy ions observed during the great magnetic storms. The storm-time NO+ structures are widely distributed and far away from the dip equator. These topside ions may also be associated with bubbles. The other possibility is that these ions were generated in the auroral zone and were driven toward the lower latitudes by the combined effects of the disturbance electric fields produced during the great storm as well as the inter-hemispheric neutral wind. Furthermore, we examined the 1024 Hz high-resolution ion density and velocity spectral. We found that as the ratio NO+/ O+ increases, the power spectral density (P) did not vary with wave number (k) in the form of in the transitional scale range. Though we did not discuss how the ion composition changes affect the plasma irregularity structures in this thesis. It is, however, an interesting subject to be further studied.