提出了一个弛豫磁流体力学模型,特别适合电磁驱动真空-等离子体系统的数值模拟.该模型和Seyler采用的弛豫模型有相似之处,即采用全电磁模型,不同的是采用忽略电子惯性项的广义欧姆定律直接作为本构来封闭麦克斯韦方程,减少了独立变量,是适合此类问题的最简模型.分析了磁流体力学模型电磁部分的色散关系,从而论证了其在真空区退化为电磁传播,在等离子体物质区退化为磁扩散近似,并且相速和群速是有上界的.改进了Seyler采用的时间离散方式,从而将时间精度从1阶提高到3阶,时间步长不受刚性源项约束,只受系统最大的特征速度确定的柯朗-弗里德里奇-列维(CFL)条件约束,便于显式计算和大规模并行化.

A relaxation magnetohydrodynamics (MHD) model is proposed for the computation of an electromagnetically driven vacuum-plasma system.It is similar to seyler’s proposal in adopting full electromagnetic model,but is different in adopting the relaxed generalized Ohm’s law (electron inertia term omitted) as a constitutive relation to close the Maxwell’s equations.Therefore it is the most simplified model for the concerned correlative problems (Hall term could also be included without increasing independent variables).The dispersion relation is given to show its transition from electromagnetic propagation in vacuum to resistive MHD in plasma in a natural way.The phase and group velocities are finite for this system.A better time stepping is adopted to give a 3rd full order convergence in time domain without the stiff relaxation term restriction.Therefore it is convenient for explicit & parallel computations.