标题： 横向等离子体加速在磁 nozzle 中的全局性质和稳定性 显示英文标题

标题： Global properties and stability of transonic plasma acceleration in the magnetic nozzle

摘要： 结果显示，收敛-发散磁场（磁喷嘴）中的跨音速等离子体加速遵循由磁场完全定义的唯一全局解。 该解在之前的近轴近似中已通过解析方法获得，此处将其与轴对称二维（rz）磁流体动力学（MHD）模拟结果进行比较。 结果显示，解析解能很好地描述轴附近区域，但也适用于任意磁面。 不同长度的喷嘴和不同等离子体速度边界值的模拟表明，等离子体流通过速度和压力分布中的类似激波过渡，切换到唯一的跨音速加速轮廓。 具有任意（非真空）初始磁场的模拟显示，磁场发生全局调整，使得跨音速加速速度轮廓遵循修改后的磁场的解析预测。 显示英文摘要

摘要： It is shown that transonic plasma acceleration in the converging-diverging magnetic field (magnetic nozzle) follows the unique global solution which is fully defined by the magnetic field. Such solution, which was analytically obtained earlier in the paraxial approximation, is compared here with results of the axisymmetric two-dimensional (rz) magnetohydrodynamics(MHD) simulations. It is shown that analytical solution describes well the region near the axis but also can be applied to arbitrary magnetic surfaces. The simulations with different length of the nozzle and different boundary values for plasma velocity show that the plasma flow switches to the unique transonic acceleration profile via the shock-like transition in the velocity and pressure profiles. The simulations with arbitrary (not vacuum) initial magnetic field demonstrate the global adjustment of the magnetic field such that the transonic acceleration velocity profile follows the analytic predictions with the modified magnetic field.