Study on Ceramic Thruster

陶瓷材料具有上级的耐热性能，是航天器推进器最有前途的材料之一。然而，它们很脆，因此到目前为止还没有在真实的飞行任务中使用。它可能由于发射时的机械振动、发射时的热冲击或空间碎片的碰撞而断裂。我们研制了一台500N级硅基整体陶瓷双组元推力器。作为开发的第一步，现有金属推力器的腔室和喷嘴被替换为陶瓷，并进行了一系列合格测试，包括机械振动测试，点火测试和冲击测试。试验结果表明，该方案在满足热冲击和发射环境要求的前提下是可行的。这意味着性能的改善是不可能的，因为喷射器的设计是决定推进剂如何燃烧和推力器如何变热的关键。目前的研究主要集中在陶瓷基推力器的实现上，而对推力器性能的研究较少。研制成功了性能与常规陶瓷推力器相当的陶瓷推力器。

Ceramics are one of the most promising materials for the spacecraft on-board thrusters because of their superior performance on heat resistance. However they are brittle, and thus they have not been used in the real flight missions so far. It might be fractured due to mechanical vibration at launch, thermal shock at firing, or by collision of space debris. We have developed a 500N class bipropellant thruster made of Si-based monolithic ceramic. As a first step of the development, the chamber and nozzle of the existing metallic thruster were replaced to ceramics, and have conducted a series of qualification tests including mechanical vibration tests, firing tests and impact test. Test results confirmed its feasibility in accordance with the thermal shock and launch environment.Momentarily, the design of the injector block is not revised from the conventional version. It means that the improvement of the performance is not expected, because the design of the injector is the key point to decide how the propellant combusts, and how the thruster becomes hot. It implies the possibility of improving the performance by allowing a higher chamber temperature.So far, this study has concentrated to realize the ceramic based thruster, without concerning the performance. As a result, the authors have successfully developed the ceramic thruster which has similar performance to the conventional ones.