碩士生: 周多諾 (印尼籍)
畢業年分: 2023年7月
論文名稱: 低功率空心陰極綜合微離子推進器的研發(中文) / Development of integrated micro-ion thrusters with low power hollow cathode (英文)
中文摘要:
成功開發完成成功大學ZAP實驗室第三代射頻（RF）離子推進器，其特色為採用輝光放電式中空陰極作為中和器。實驗結果顯示，該中空陰極能在低直流功率下高效運作；於0.05 A電流下，其擊穿電壓約為800–930 V，並可在200–300 V區間穩定維持放電，整體功率需求低於15 W，若進一步提高電流供應則可降至10 W以下。相較於其他中和器設計，輝光放電中空陰極具備結構緊湊、堅固耐用及可瞬間啟動等優勢。
第三代RF離子推進器亦進行多項改良，包括新增推進劑分配器以及重新設計離子光學系統。分配器將氬氣推進劑導入至電離器壁附近，該區域具有最大渦電場與高電子溫度，有助於提升電離效率。同時，離子光學系統透過降低開孔率並避免網格邊緣設孔，以維持內部壓力並減緩電漿在電離器壁附近的密度下降，進而改善推進效能與羽流集中度。
然而，目前所採用的絕緣材料──聚四氟乙烯（PTFE）與聚醚醚酮（PEEK）──因熔點較低而存在熱限制，可能影響長時間運作的穩定性。因此，後續研究需著重於開發更耐高溫的絕緣材料，並進行更詳細的電漿診斷，以深化對輝光放電中空陰極RF離子推進器性能之理解。本研究證實了低功率、緊湊型RF離子推進器結合輝光放電中空陰極的可行性，展現其於小型衛星推進應用上的潛力。
英文摘要:
The third generation of the NCKU ZAP Lab radio-frequency (RF) ion thruster, featuring a glow discharge hollow cathode, has been successfully developed and tested. The glow discharge hollow cathode demonstrated efficient performance at low DC power levels, requiring less than 15 W of power and sustaining operation at 200–300 V after an initial breakdown at approximately 800–930 V with a current of 0.05 A. By increasing the current supply, the required power can be further reduced to below 10 W. In addition to its low power demand, the glow discharge hollow cathode provides a compact, robust design with the advantage of near-instant start-up, distinguishing it from other neutralizer cathode technologies.
Several design advancements were incorporated into the third-generation RF ion thruster. A gas distributor was added to inject argon propellant near the ionizer wall, coinciding with regions of maximum induced eddy fields and elevated electron temperature, thereby enhancing ionization efficiency. Furthermore, the ion optics system was redesigned by reducing the open area ratio and eliminating borings at the periphery of the grid system. These modifications help sustain internal pressure and mitigate plasma density losses near the ionizer wall, improving overall thruster performance and plume collimation.
Despite these improvements, challenges remain regarding the cathode insulator materials. The current use of polytetrafluoroethylene (PTFE) and polyether ether ketone (PEEK) introduces thermal limitations due to their relatively low melting points, potentially impacting long-term operational stability. Future work should focus on optimizing insulator materials with higher thermal resistance and conducting detailed plasma diagnostics to further characterize the performance of RF ion thrusters integrated with glow discharge hollow cathodes.
This research demonstrates the feasibility of compact, low-power RF ion thrusters with glow discharge cathodes, offering promising potential for small satellite propulsion applications.
