已於一九九九年一月發射之中華衛星一號上，放置用以觀測日地物理之儀器，其儀器名稱為電離層電漿及電動效應儀，簡稱 IPEI 。此儀器上有四個探測器，其中一儀器為阻滯電位分析儀，可用以量測中華衛星一號在電離層中飛行所經路徑上的正離子成份、溫度和犄角方向電漿流速。本論文將提出一套模擬三維空間中電子和正離子於阻滯電位分析儀內運動之電腦數值模式，並且與一維空間的流量理論作比較。在電腦模式中顯示出幾點重要的發現：其一，由於氫離子重量較輕，能通過壓制網而到達收集器的氫離子數目小於到達收集器的氧離子數目。其二，正離子的透明度不可僅由網線的粗細或網眼的大小來決定，網與網之間的排列方式亦為一重要因素。其三，在模擬中顯示，當阻滯電位超過離子截止能量附近時，仍有可觀之離子流存在，此與一維流量理論所得到結果不同。其四，當網眼的尺度大於電子的Debye長度時，電子將可通過壓制網直達收集器。 One of the Ionospheric Plasma and Electrodynamics Instrument (IPEI) payload onboard the ROCSAT-1 spacecraft is a Retarding Potential Analyzer (RPA) to measure the ionospheric plasma composition, temperature, and the ram velocity of the flow. A 3-D computer model has been developed to simulate the ion and electron motions inside the RPA of the IPEI payload. The dynamical changes in the charged particles* motions corresponding to different electric potential profiles inside the RPA detector resulted in some distinctive measuring characteristics of the RPA detector which show discrepancies in the measured of currents at the collector plate between the analytical model and the computer simulation. The important discoveries in the computer model are: (a) Due to light mass, the hydrogen ion fluxes to reach the collector are less than the oxygen ion fluxes collected by the collector. (b) Ion transparency can not be represented by the physical grid sizes in the detector. The alignments of the grid wires will also affect the ion transparency. The grid planes should be aligned for the maximum optical transparency to detect light ion fluxes. (c) Cut off energy for ions is not as sharp as indicated in the analytical model. The contamination in the collector current from ion species is possible. (d) Electron contamination at the collector plate is noticed if the mesh sizes are larger than the electron Debye length.
