A numerical model was developed to understand the time evolution of a wake structure around a CubeSat moving in a plasma with transonic speed. A CubeSat operates in the F2 layer of ionosphere with an altitude of 300--600 Km. The average plasma density varies between 10--6 cm --3 -- 10--9 cm--3 and the temperature of ions and electrons is found between 0.1--0.2 eV. The study of a wake structure can provide insights for its effects on the measurements obtained from space instruments. The CubeSat is modeled to have a metal surface, which is a realistic assumption, with a negative electric potential. To solve the equations of plasma, the numerical difference equations were obtained by discretizing the fluid equations of the plasma along with nonlinear Poisson's equation. The electrons were assumed to follow the Boltzmann's relation and the dynamics of ions was followed using the fluid equations. The initial and boundary conditions for the evolution of the structure are discussed. The computation was compared to the analytical solution for a 1D problem before being applied to the 2D model. There was a good agreement between the numerical and analytical solution. In the 2D simulation, we observe the formation of plasma wake structure around the CubeSat. The plasma wake structure consists of rarefaction region where ion density and ion velocity decreases compared to the initial density and velocity.
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机译：开发了一个数值模型以了解绕立方声卫星以跨音速运动的苏醒结构的时间演化。 CubeSat在电离层的F2层中运行，高度为300--600 Km。平均血浆密度在10--6 cm --3-10--9 cm--3之间变化，离子和电子的温度在0.1--0.2 eV之间。对尾迹结构的研究可以提供其对从太空仪器获得的测量结果的影响的见解。 CubeSat被建模为具有一个金属表面，这是一个现实的假设，具有负电势。为了解决等离子体方程，通过将等离子体的流体方程与非线性泊松方程离散化来获得数值差分方程。假定电子遵循玻尔兹曼关系，并且使用流体方程跟踪离子的动力学。讨论了结构演化的初始条件和边界条件。在将计算应用到2D模型之前，将其与1D问题的解析解进行了比较。数值解决方案与解析解决方案之间达成了良好的共识。在2D模拟中，我们观察到CubeSat周围等离子体唤醒结构的形成。等离子体唤醒结构由稀疏区组成，在稀疏区中，离子密度和离子速度比初始密度和速度降低。
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