论文标题
多束粒子速度分布的多光束能量力矩
Multi-beam Energy Moments of Multibeam Particle Velocity Distributions
论文作者
论文摘要
高分辨率电子和离子速度分布F(V)由N有效地分离梁组成,已通过NASA的磁层多尺度任务(MMS)观测值和重新连接模拟来测量。通常使用标准速度矩通常假设整个分布的单个平均值 - 速度,这可能会导致多层F(V)的违反直觉结果。一个示例是一对相等和相反的冷粒梁的(假)标准热能矩,即使每个光束的热能为零,也不为零。相比之下,两个或多个光束的多束力矩没有错误的热能。通过采取每个光束的标准力矩,然后将横梁求和来获得多束力矩。在本文中,我们将概括这些概念,探索它们的后果,并将其应用于F(V),即Tri-Maxwellians的总和。标准能量矩和多束能量矩具有连贯和不连贯的形式。不连贯的力矩的例子是热能密度,压力和热能通量(焓通量加热通量)。相应的相干力矩是庞大的动能密度,RAM压力和大量动能通量。不一致力矩的假部分定义为标准不一致力矩与相应的多束矩之间的差异。一对相应的连贯和不连贯的力矩的总和将称为未分解的力矩。未分解的力矩独立于总和是标准光线还是多束,因此在研究测量f(v)的力矩时具有优势。
High resolution electron and ion velocity distributions, f(v), which consist of N effectively disjoint beams, have been measured by NASA's Magnetospheric Multi-Scale Mission (MMS) observatories and in reconnection simulations. Commonly used standard velocity moments generally assume a single mean-flow-velocity for the entire distribution, which can lead to counterintuitive results for a multibeam f(v). An example is the (false) standard thermal energy moment of a pair of equal and opposite cold particle beams, which is nonzero even though each beam has zero thermal energy. By contrast, a multibeam moment of two or more beams has no false thermal energy. A multibeam moment is obtained by taking a standard moment of each beam and then summing over beams. In this paper we will generalize these notions, explore their consequences and apply them to an f(v) which is sum of tri-Maxwellians. Both standard and multibeam energy moments have coherent and incoherent forms. Examples of incoherent moments are the thermal energy density, the pressure and the thermal energy flux (enthalpy flux plus heat flux). Corresponding coherent moments are the bulk kinetic energy density, the RAM pressure and the bulk kinetic energy flux. The false part of an incoherent moment is defined as the difference between the standard incoherent moment and the corresponding multibeam moment. The sum of a pair of corresponding coherent and incoherent moments will be called the undecomposed moment. Undecomposed moments are independent of whether the sum is standard or multibeam and therefore have advantages when studying moments of measured f(v).