Whistler instability stimulated by the suprathermal electrons present in space plasmas
Whistler instability stimulated by the suprathermal electrons present in space plasmas
复制标题
DOI：
10.1007/s10509-019-3661-6
复制
发表时间：
2019-10-01
影响因子：
1.9
通讯作者：
Fichtner, H.
中科院分区：
文献类型：
--
作者：
Lazar, M.;Lopez, R. A.;Fichtner, H.
在缺乏有效碰撞的情况下，等离子体粒子分布与热平衡的偏差由自生不稳定性控制。哨声不稳定性是一个臭名昭著的例子，通常负责调节空间等离子体中观察到的电子温度各向异性（A=T垂直于/T平行于磁场方向），例如，太阳风和行星磁层。存在于这些环境中的超热电子改变了等离子体的色散和稳定性，对动力学不稳定性和由此产生的波动产生预期的后果，这反过来又散射了电子并降低了它们的各向异性。为了捕捉这些相互作用，我们使用准线性动力学方法和PIC模拟，这提供了一个全面的表征哨声不稳定性的影响下的超热电子。分析进行了各种各样的等离子体条件，范围从低β等离子体遇到的外日冕或行星磁层的高β太阳风特性大日光层的距离。哨声涨落在超热电子的增强下，激发了温度各向异性的弛豫，且这种影响随等离子体β参数的增大而增大。
In the absence of efficient collisions, deviations from thermal equilibrium of plasma particle distributions are controlled by the self-generated instabilities. The whistler instability is a notorious example, usually responsible for the regulation of electron temperature anisotropy A=T perpendicular to/T parallel to respective to the magnetic field direction) observed in space plasmas, e.g., solar wind and planetary magnetospheres. Suprathermal electrons present in these environments change the plasma dispersion and stability properties, with expected consequences on the kinetic instabilities and the resulting fluctuations, which, in turn, scatter the electrons and reduce their anisotropy. In order to capture these mutual effects we use a quasilinear kinetic approach and PIC simulations, which provide a comprehensive characterization of the whistler instability under the influence of suprathermal electrons. Analysis is performed for a large variety of plasma conditions, ranging from low-beta plasmas encountered in outer corona or planetary magnetospheres to a high-beta solar wind characteristic to large heliospheric distances. Enhanced by the suprathermal electrons, whistler fluctuations stimulate the relaxation of temperature anisotropy, and this influence of suprathermals increases with plasma beta parameter.