碩士生: 李灄甡
畢業年分: 2025年7月
論文名稱: 電網系統於四公分射頻離子推進器之性能影響(中文) / The effect of ion optics system on the performance of 4 cm radio-frequency ion thruster (英文)
中文摘要:
離子推進器因具備高比衝、高效率與長壽命等特性，已廣泛應用於深太空探測與高精度軌道控制。射頻離子推進器（RF ion thruster）透過射頻電漿激發，不需使用熱陰極元件，可延長壽命並簡化結構，特別適合小型化與微衛星任務。推進器性能高度依賴於電漿生成與電網系統，其中電網電壓直接影響離子加速與羽流形態，對推力輸出與壽命至關重要。
本研究針對直徑 4 公分射頻離子推進器，探討不同電網偏壓對羽流特性與電網行為之影響。推進器採用感應耦合電漿（Inductively Coupled Plasma, ICP）為電漿來源，配置 screen grid 與 accelerator grid 兩層式電網，並以氬氣為推進劑進行實驗。
透過法拉第探針與電網電流量測，本研究系統性分析不同電壓條件下羽流電流分佈與張角變化。結果顯示，隨 screen grid 電壓提升，羽流電流顯著上升；而在 accelerator grid 施加負偏壓時，初期會擴大羽流張角，但隨偏壓進一步增加，張角逐漸收斂，且電網電流下降。此一結果證實電網偏壓在離子軌跡調控與羽流集中性中扮演關鍵角色。
綜合而言，本研究釐清了兩層式電網系統電壓參數對羽流與電網電流的影響機制，對於射頻離子推進器性能優化與電網設計具重要參考價值。
英文摘要:
Ion thrusters, with their advantages of high specific impulse, high efficiency, and long operational lifetime, have become indispensable electric propulsion technologies for deep-space exploration and precise orbit control. The radio-frequency ion thruster (RF ion thruster), which employs RF plasma excitation, eliminates the need for thermionic cathodes, thereby extending operational lifetime and simplifying structural design, making it an ideal candidate for miniaturization and microsatellite missions. The performance of such thrusters strongly depends on plasma generation and grid system configuration, where grid voltages play a critical role in determining ion acceleration, plume characteristics, thrust output, and overall lifetime.
This study investigates the effects of grid voltage variation on the performance of a 4 cm diameter RF ion thruster. The thruster employs an inductively coupled plasma (ICP) source and is equipped with a two-stage grid system consisting of a screen grid and an accelerator grid. Argon gas was used as the propellant in the experiments.
Through measurements of plume current distribution and divergence angles using a Faraday probe, along with grid current monitoring, this work systematically analyzes plume behavior under different voltage conditions. Results indicate that increasing the screen grid voltage leads to a significant rise in plume current. In contrast, applying a negative bias to the accelerator grid initially increases the plume divergence angle; however, as the bias is further increased, the angle converges while the grid current decreases. This behavior highlights the critical role of grid bias in shaping ion trajectories and enhancing plume collimation.
In conclusion, this study elucidates the influence of two-stage grid voltage parameters on plume characteristics and grid currents, providing valuable experimental insights for optimizing RF ion thruster performance and grid design.
