论文标题

比较无碰撞等离子体环境中的逆梁和温度各向异性驱动的大道电子不稳定性

Comparing the counter-beaming and temperature anisotropy driven aperiodic electron firehose instabilities in collisionless plasma environments

论文作者

Moya, Pablo S., Lopez, Rodrigo A, Lazar, Marian, Poedts, Stefaan, Shaaban, Shaaban M

论文摘要

电子消防型不稳定性是研究最多的动力学不稳定性之一,尤其是在空间等离子体的背景下,其动力学主要由无碰撞波颗粒相互作用控制。本文对因各向异性温度或电子反聚体种群而激发的上的电子消防型不稳定性进行了比较分析。两个对称的反梁提供了一种有效的动力学各向异性,类似于单个(非驱动)种群的温度各向异性,沿磁场方向的温度大于垂直方向的温度。因此,反梁等离子体容易受到诸如消防状态的不稳定性(FIS),平行和倾斜的分支。在这里,我们专注于倾斜的横梁FI,当自由能由对称的柜台提供时,这也是一个aperiodic。我们的结果表明,对于相对较小的漂移或横梁速度($ u $),不超过热速度($α$),就有相同的波浪数和相同的斜角(相对于磁场方向)的间隔,而上的FIS存在于相同的间隔中,但相同的频率(相对于磁场方向),但逆转fi(CBFI)的增长速度始终比那些温度更高。但是,对于$ u/α> 1 $,还可以预测另一个静电两流不稳定性(ETSI),其增长率可能高于CBFI的增长率,在这种情况下,可能会占主导地位。

The electron firehose instabilities are among the most studied kinetic instabilities, especially in the context of space plasmas, whose dynamics is mainly controlled by collisionless wave-particle interactions. This paper undertakes a comparative analysis of the aperiodic electron firehose instabilities excited either by the anisotropic temperature or by the electron counter-beaming populations. Two symmetric counter-beams provide an effective kinetic anisotropy similar to the temperature anisotropy of a single (non-drifting) population, with temperature along the magnetic field direction larger than that in perpendicular direction. Therefore, the counter-beaming plasma is susceptible to firehose-like instabilities (FIs), parallel and oblique branches. Here we focus on the oblique beaming FI, which is also aperiodic when the free energy is provided by symmetric counter-beams. Our results show that, for relative small drifts or beaming speeds ($U$), not exceeding the thermal speed ($α$), the aperiodic FIs exist in the same interval of wave-numbers and the same range of oblique angles (with respect to the magnetic field direction), but the growth rates of counter-beaming FI (CBFI) are always higher than those of temperature anisotropy FI (TAFI). For $U/α> 1$, however, another electrostatic two-stream instability (ETSI) is also predicted, which may have growth rates higher than those of CBFI, and may dominate in that case the dynamics.

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源