多束粒子速度分布的多束能量矩
Multi-beam Energy Moments of Multibeam Particle Velocity Distributions
摘要：
高分辨率的电子和离子速度分布，f（v），其中包括N个有效的不相交的光束，已被美国宇航局的磁层多尺度任务（MMS）观测站和重连模拟测量。通常使用的标准速度矩通常假设整个分布的平均流速是单一的，这可能导致多波束f（v）的反直观结果。一个例子是一对相等且相反的冷粒子束的（假）标准热能矩，即使每个束具有零热能，它也是非零的。相比之下，两个或更多个光束的多光束矩没有假热能。通过对每个梁取一个标准矩，然后对多个梁求和，得到多梁矩。在本文中，我们将推广这些概念，探讨其后果，并将其应用到一个f（v），这是三个麦克斯韦之和。标准和多光束能量矩都有相干和非相干的形式。非相干矩的例子是热能密度、压力和热能通量（焓通量加热通量）。相应的相干矩是体动能密度、RAM压力和体动能通量。非相干矩的假部分定义为标准非相干矩与相应的多光束矩之差。一对相对应的相干矩和非相干矩之和将被称为未分解矩。未分解的矩与和是标准的还是多波束的无关，因此在研究测量的f（v）的矩时具有优势。
英文摘要：
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).
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
