2D particle-in-cell simulations of the electron temperature anisotropy driven whistler instability in plasmas having kappa velocity distributions
2D particle-in-cell simulations of the electron temperature anisotropy driven whistler instability in plasmas having kappa velocity distributions
复制标题
具有 kappa 速度分布的等离子体中电子温度各向异性驱动的哨声不稳定性的二维细胞内粒子模拟
DOI：
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
R. Mace
中科院分区：
文献类型：
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作者：
R. F. Abdul;A. Matthews;R. Mace
本研究提出了二维粒子模拟的结果，电子温度各向异性驱动的哨声不稳定性的等离子体中的电子物种是由一个bi-kappa速度分布建模。这些模拟利用我们之前开发的方法来生成初始多维kappa速度分布。在PIC模拟中使用多维Kappa载荷提供了对具有非平衡速度分布的等离子体中的波演化的非线性制度的见解。考虑三种情况，对应于κ e = 2、3和∞（麦克斯韦情况）。由于合理的模拟运行时间所需的电子各向异性的大值的使用，麦克斯韦电子运行具有最快的增长率，最早达到饱和。在κ e = 2的情况下，增长速率最慢。波动场的频谱分析揭示了相当大的波强度的频率和波数，满足线性哨声波色散关系。在kappa分布的运行中，最强烈的波动区域包括的频率和波数，仅定性地与线性哨声波理论相一致。结果表明，饱和后，有一定程度的朗道阻尼的斜哨声模式，返回能量的电子物种。斜模式的阻尼率在麦克斯韦情况下最高，在κ e = 2时最低。在平行于环境磁场的方向上的电子显着的超热加速的证据也被观察到。因此，电子分布的幂律指数被各向异性的哨声湍流所降低。
This study presents the results of 2D particle-in-cell (PIC) simulations of the electron temperature anisotropy driven whistler instability for plasmas in which the electron species is modeled by a bi-kappa velocity distribution. These simulations utilize our previously developed method to generate the initial multi-dimensional kappa velocity distributions. The use of multi-dimensional kappa loadings in PIC simulations provides insights into the non-linear regime of wave evolution in plasmas having non-equilibrium velocity distributions. Three cases are considered, corresponding to κ e = 2 , 3, and ∞ (Maxwellian case). Owing to the use of a large value of electron anisotropy required for reasonable simulation run times, the Maxwellian electron run has the fastest growth rate, reaching saturation earliest. The κ e = 2 case exhibits the slowest growth rate. Spectral analysis of the fluctuating fields reveals considerable wave intensity at frequencies and wavenumbers that satisfy the linear whistler wave dispersion relation. In the runs with kappa distributions, the regions of most intense fluctuations comprise frequencies and wavenumbers that agree only qualitatively with linear whistler wave theory. The results suggest that after saturation, there is some degree of Landau damping of the oblique whistler modes, which returns energy to the electron species. The rate of damping of the oblique modes is highest in the Maxwellian case and lowest for κ e = 2. Evidence of significant superthermal acceleration of electrons in the direction parallel to the ambient magnetic field is also observed. Thus, the power-law index of the electron distribution is reduced by the anisotropic whistler turbulence produced.
影响因子：
16.6
作者：
Jinxing Li;J. Bortnik;X. An;Wen Li;V. Angelopoulos;R. Thorne;C. Russell;B. Ni;X. Shen
通讯作者：
Jinxing Li;J. Bortnik;X. An;Wen Li;V. Angelopoulos;R. Thorne;C. Russell;B. Ni;X. Shen