Nicolaou Georgios, Livadiotis George
Department of Space and Climate Physics, Mullard Space Science Laboratory, University College London, Dorking, Surrey RH5 6NT, UK.
Southwest Research Institute, San Antonio, TX 78238, USA.
Entropy (Basel). 2020 May 13;22(5):541. doi: 10.3390/e22050541.
The velocities of space plasma particles often follow kappa distribution functions, which have characteristic high energy . The of these distributions are associated with low particle flux and, therefore, it is challenging to precisely resolve them in plasma measurements. On the other hand, the accurate determination of kappa distribution functions within a broad range of energies is crucial for the understanding of physical mechanisms. Standard analyses of the plasma observations determine the plasma bulk parameters from the statistical moments of the underlined distribution. It is important, however, to also quantify the uncertainties of the derived plasma bulk parameters, which determine the confidence level of scientific conclusions. We investigate the determination of the plasma bulk parameters from observations by an ideal electrostatic analyzer. We derive simple formulas to estimate the statistical uncertainties of the calculated bulk parameters. We then use the forward modelling method to simulate plasma observations by a typical top-hat electrostatic analyzer. We analyze the simulated observations in order to derive the plasma bulk parameters and their uncertainties. Our simulations validate our simplified formulas. We further examine the statistical errors of the plasma bulk parameters for several shapes of the plasma velocity distribution function.
空间等离子体粒子的速度通常遵循具有特征高能的κ分布函数。这些分布的尾部与低粒子通量相关，因此，在等离子体测量中精确解析它们具有挑战性。另一方面，在广泛的能量范围内准确确定κ分布函数对于理解物理机制至关重要。对等离子体观测的标准分析从下划线分布的统计矩确定等离子体整体参数。然而，同样重要的是量化导出的等离子体整体参数的不确定性，这决定了科学结论的置信水平。我们研究通过理想静电分析仪从观测中确定等离子体整体参数。我们推导了简单公式来估计计算出的整体参数的统计不确定性。然后我们使用正向建模方法来模拟典型的平顶静电分析仪的等离子体观测。我们分析模拟观测以推导等离子体整体参数及其不确定性。我们的模拟验证了我们的简化公式。我们进一步研究了几种等离子体速度分布函数形状下等离子体整体参数的统计误差。
