脉冲等离子体推力器放电能量分布式释放的多物理场匹配研究

The ablated pulsed plasma thruster (APPT) is one of the propulsion systems for the micro satellite. However,the efficiency of the APPT is very low (only about 10%). The mechanism study on the discharge energy distribution release in an APPT is proposed in the project, in order to imporve the efficiency of an APPT. Now the energy for an APPT is discharged only on one position during the single time of microsecond order.In stead, the idea in the project is reseasing the discharge energy for an APPT in more positions on the channel of the APPT and during more times of microsecond order.The purpose of the idea is to match the fast discharge process (about microsecond order) to slow ablation process (about millisecond), and make the gas ioned and accelerated, finally improve the efficiency of an APPT.A Knudsen mathematical model for the ablation and a mathematical model for the ionization and plasma movement are put forward in the project.The models will be used to simulate the discharge energy distribution release process in an APPT. What's more, the compromise strategy of the realease between the positions and between the times will be studied. In addition, the experiments on how to realize the discharge energy distribution release in an APPT will also be carried out in the project, so as to confirm the theoretical results.The expectant achievements of the project will not only show how the discharge energy ideal distribution release is, but also provide the theory on the compromise strategy of the distribution release and supply theorecial reference for the design of an APPT with high efficiency.

固体烧蚀型脉冲等离子体推力器（APPT）是微小卫星的理想推进系统之一，但是其效率较低（小于10%）的缺点限制了它的进一步发展和应用。本项目为了提高APPT的工作效率，提出了将目前APPT放电能量在单点单时段的释放过程改变为沿通道的多点和多时段分布式释放过程的思路，期望通过该思路使得APPT微秒尺度放电形成的电磁场与APPT固体推进剂毫秒尺度烧蚀形成的气体密度场相匹配，从而实现APPT通道内多时间尺度物理场的协同工作，最终可以高效电离和加速工质，提高APPT的工作效率。通过本项目研究，有望形成APPT放电能量多点多时段的理想分布式释放的多物理场匹配理论，为高效率APPT的设计提供新的思路。

本项目针对固体烧蚀型脉冲等离子体推力器（APPT）效率较低的缺陷，提出了将APPT放电能量在单点单时段的释放过程改变为沿通道的多点和多时段分布式释放过程的思路，以实现APPT通道内多时间尺度物理场的协同工作，最终可以高效电离和加速工质，提高APPT的工作效率。为实现这一目标，本项目通过仿真和实验手段，研究APPT能量分布释放的多物理场匹配规律。首先，基于固体聚合物烧蚀机理、气体电离机理和电流片加速假设，建立了能够模拟APPT推进剂烧蚀、中性气体电离以及等离子体非连续流动的数值模型；其次，利用所建的模型，对不同工况下APPT的工作过程进行仿真，并对仿真结果进行分析，获得APPT工作过程中的放电能量分布式释放机制；之后，基于新模型，对多点多时段放电脉冲等离子体推力器（Distributed Discharge Ablative Pulsed Plasma Thruster, DD-APPT）的工作过程进行数值仿真研究，探索了DD-APPT放电能量分配对性能的影响，发现提高次级放电能量有利于推力器性能；最后，根据前期理论分析和仿真研究的结论，设计了一套DD-APPT样机，并测取了该样机的工作特性参数，用于计算不同能量分配下样机推力产生的各物理过程消耗的能量值，并据此总结了APPT设计参数对其能量损失的影响规律。DD-APPT样机实验结果表明，使用分布式放电布局后，APPT的效率大幅度提高。本项目为提高APPT工作效率奠定了理论基础。