Study on Ceramic Thruster

陶瓷材料具有优异的耐热性能，是航天器星载推进器最有前途的材料之一。然而，它们是易碎的，因此到目前为止还没有在真正的飞行任务中使用。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破裂。研制了一种由硅基单片陶瓷制成的500N级双组元推进器。作为研制的第一步，将现有金属推进器的燃烧室和喷管更换为陶瓷，并进行了包括机械振动试验、点火试验和冲击试验在内的一系列合格试验。试验结果验证了该方案在热震和发射环境下的可行性，喷油器模块的设计没有对常规版本进行修改。这意味着性能的改善是不可预期的，因为喷射器的设计是决定推进剂如何燃烧、推进器如何变热的关键。这意味着通过允许更高的燃烧室温度来改善性能的可能性。到目前为止，本研究主要集中在实现陶瓷基推进器，而不是考虑性能。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.