LIPS-300离子推力器栅极热变形特点实验分析

为探究LIPS-300离子推力器在工作过程中栅极热变形的规律与特点，设计了大气环境下离子推力器双栅极热变形实验，以一环形加热器模拟实际工作时的等离子体热源。实验研究发现:球面栅极在加热过程中急剧变形，同时屏栅变形量大于加速栅，导致栅极间距减小；在冷却过程中，双栅迅速回复变形，栅极间距同步回复。其次,研究发现栅极中心位移在加热过程中的峰值回落现象，与在冷却过程中的负位移现象，同时发现冷却速率对负位移的大小有着不容忽视的影响。为研究上述现象的起因，对栅极组件的径向位移进行了采集，发现栅极安装环的变形是其根本原因。在结构与温度的综合影响下，栅极安装环的变形相较球面栅极更为缓慢，而其受热膨胀会拉伸球面栅极，导致球面栅极中心拱高减小，中心位移峰值回落。

Analysis of Thermal Deformation Characteristics of LIPS-300 Ion Thruster Grid

In order to investigate the characteristics of the thermal deformation of the LIPS-300 ion thruster in the working process, a double grid thermal deformation experiment is designed for the ion thruster in the atmosphere, and a loop heater is used to simulate the plasma heat source. It is observed that the spherical grid deforms sharply during the heating process, and the deformation of the screen grid is larger than that of the accelerator grid, which results in the decrease of the grid gap, while during the cooling process, the double grid rapidly recovers and the grid gap increases rapidly. Secondly, the peak drop of the center displacement of the grid in the heating process and the negative displacement in the cooling process are observed. At the same time, it is found that the cooling rate has an important influence on the magnitude of the negative displacement. In order to study the causes of the above phenomenon, the radial displacement of the grid assembly is collected, and the deformation of the grid mounting ring is found to be the fundamental cause. Under the influence of the structure and temperature, the deformation of the grid mounting ring is slower than that of the spherical grid, and its thermal expansion will stretch the spherical grid, resulting in the peak drop of the spherical grid center displacement.