太阳风磁帆推进性能数值研究

Numerical study on propulsion performance of solar wind magnetic sail

利用考虑行星际磁场作用的磁流体动力学模型,建立了磁帆三维数值模拟方法,对计算方法的可靠性进行了验证,发现了线圈尾部的磁重联现象,研究了太阳风来流速度、等离子体离子数密度以及攻角对磁帆推进性能的影响。得出以下结论:不同速度、不同离子数密度的太阳风主要通过改变z方向电流的大小改变洛伦兹力,进而影响磁帆的推进性能:太阳风离子数密度恒定时,随着来流速度由30 km/s逐渐增大至75 km/s,z方向电流最大值由4 205 A/m~2增至14 709 A/m~2,磁帆所受推力由3.39 N增至13.40 N;太阳风来流速度恒定时,随着离子数密度由1.8×10^(19) m^(-3)增大至4.5×10^(19) m^(-3),z方向电流最大值由6 039 A/m~2增至10 585 A/m~2,磁帆所受推力由6.62 N增至12.27 N。磁帆攻角变化,主要通过磁场构型的变化影响磁帆推进性能:攻角为0°和90°时的磁层半径分别为0.14 m和0.18 m,磁帆所受推力分别为6.62 N和11.03 N,由此推测实际应用中保持线圈轴线与太阳风来流方向平行,可获得更大推力。系统研究了相关因素对磁帆推进性能的影响,可为磁帆的推力调节研究提供参考和支持,对未来磁帆的深入研究具有重要的参考价值。

The three-dimensional numerical simulation of the solar wind magnetic sail was established with the magnetohydrodynamic(MHD) model considering the interplanetary magnetic field.The verification of the calculation method was accomplished by comparison with experimental data.In addition,the observation and confirmation of the magnetic reconnection were achieved at the tail of the coil.The propulsion performance of the magnetic sail was studied in terms of the incoming velocity,the plasma ion number density and the attack angle of of the solar wind.The solar wind with different velocities and different ion number densities mainly influenced the Lorentz force by affecting the current in the z direction,which further affected the propulsion performance of the magnetic sail.As incoming velocity increased from 30 km/s to 75 km/s of solar wind with fixed ion number density,the maximum current in z direction increased from 4 205 A/m~2 to 14 709 A/m~2,and the thrust of magnetic sail increased from 3.39 N to 13.40 N.As the ion number density increased from 1.8×10~(19) m~(-3) to 4.5×10~(19) m~(-3) of solar wind with fixed incoming velocity,the maximum current in z direction increased from 6 039 A/m~2 to10 585 A/m~2,and the thrust increased from 6.62 N to 12.27 N.The variation of the attack angle affected the propulsion performance of magnetic sail by influencing the configuration of magnetic field.With the attack angle of 0° and 90°,the radius of the magnetic cavity was 0.14 m and 0.18 m,respectively.Correspondingly,the thrust of the magnetic sail was 6.62 N and 11.03 N,respectively.It was inferred that larger thrust can be obtained by keeping the axis of the coil parallel to the direction of the solar wind in practical application.The influence of relevant factors on the propulsion performance of magnetic sail was studied systematically,which can provide a reference and support for the research of thrust regulation of the sail,and has important reference value for the further study of magnetic sail.