论文标题
电荷饥饿方案中alfvén波的传播
Propagation of Alfvén waves in the charge starvation regime
论文作者
论文摘要
我们提出了在电荷饥饿方面传播Alfvén波的数值仿真结果。这是血浆密度低于为波提供电流所需的临界值所需的临界值。我们分析了一个保守的方案，其中AlfvénWaves从电荷密度超过临界值并以高洛伦兹因子沿临界值的区域接收电荷。由alfvén波和带有电荷的系统组成的系统，我们称之为电荷载体alfvén波（CC-AW），通过具有小但非零等离子体密度的介质移动。我们发现，CC-AW与固定介质之间的相互作用具有2串等不稳定性，从而导致沿未扰动的磁场的方向出现强电场。这种不稳定性的生长速率是CCAW遇到的介质的等离子频率。我们的数值代码遵循数百个波周期的系统。数值计算表明，电场的最终强度是Alfvén波幅度的几％。在线性生长阶段与不稳定性相关的正弦振荡电流产生的辐射很少。但是，在非线性相中，波动的电流密度在血浆频率附近产生强烈的EM辐射，并限制了不稳定性的生长。
We present numerical simulation results for the propagation of Alfvén waves in the charge starvation regime. This is the regime where the plasma density is below the critical value required to supply the current for the wave. We analyze a conservative scenario where Alfvén waves pick up charges from the region where the charge density exceeds the critical value and advect them along at a high Lorentz factor. The system consisting of the Alfvén wave and charges being carried with it, which we call charge-carrying Alfvén wave (CC-AW), moves through a medium with small, but non-zero, plasma density. We find that the interaction between CC-AW and the stationary medium has a 2-stream like instability which leads to the emergence of a strong electric field along the direction of the unperturbed magnetic field. The growth rate of this instability is of order the plasma frequency of the medium encountered by the CC-AW. Our numerical code follows the system for hundreds of wave periods. The numerical calculations suggest that the final strength of the electric field is of order a few percent of the Alfvén wave amplitude. Little radiation is produced by the sinusoidally oscillating currents associated with the instability during the linear growth phase. However, in the nonlinear phase, the fluctuating current density produces strong EM radiation near the plasma frequency and limits the growth of the instability.
