基于等离子体能量密度的航天器表面电位估计

Evaluation of Spacecraft Surface Potential Based on Plasma′s Energy Density

空间等离子体状态对航天器表面充电具有重要影响。为了利用等离子体状态参数表征可能发生的严重充电事件,研究了基于等离子体能量密度的航天器表面电位快速估计方法。首先通过数值仿真考察了航天器表面铝材料表面电位随等离子体浓度和温度的变化关系,得出了表面电位关于等离子体能量密度的线性拟合公式。然后对拟合公式进行归一化处理,提出了利用无量纲系数估计航天器表面电位的方法,并解释了拟合系数的物理意义。利用单变量变化趋势对估计式中的系数进行拟合,可得到与数值仿真结果十分接近的拟合结果。将电位估计方法应用到其他几种常用的航天器表面材料上,均取得了较好的估计结果。该电位估计方法能够快速得到等离子体参数波动情况下的航天器表面电位变化结果,有助于实现基于空间等离子体天气的航天器表面严重带电事件的快速预报。

The condition of space plasma plays an important role on the spacecraft surface charging.In order to predict the possible severe charging event using plasma′s characteristic parameters,a kind of fast evaluation method for spacecraft surface charging is studied based on the plasma′s energy density.Firstly,the variations of surface potential for spacecraft-used aluminum with respect to the ambient plasma′s density and temperature are obtained by numerical simulation,and a fitting expression based on plasma′s energy density is obtained.Secondly,normalization is performed to the fitting formula and the surface potential evaluation method using non-dimensional parameters is proposed,in which the parameters′physical meaning is provided.Using single variable dependence,the fitting parameters are derived and the evaluation results are very close to that from numerical simulation.The proposed evaluation method is applied to several other spacecraft surface material,and satisfactory results are obtained.This evaluation method can quickly get the surface charging results in the situation where the plasma′s condition fluctuates.So it is useful for the fast prediction of severe spacecraft charging based on space weather.