The challenge to understand the zoo of particle transport regimes during resonant wave-particle interactions for given survey-mode wave spectra
The challenge to understand the zoo of particle transport regimes during resonant wave-particle interactions for given survey-mode wave spectra
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DOI：
10.3389/fspas.2024.1332931
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发表时间：
2024-03
影响因子：
3
通讯作者：
Oliver Allanson;Donglai Ma;A. Osmane;Jay M. Albert;Jacob Bortnik;Clare E. J. Watt;Sandra C. Chapman;Joseph Spencer;Daniel J. Ratliff;Nigel P. Meredith;Thomas Elsden;Thomas Neukirch;David P. Hartley;Rachel Black;N. Watkins;S. Elvidge
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作者：
Oliver Allanson;Donglai Ma;A. Osmane;Jay M. Albert;Jacob Bortnik;Clare E. J. Watt;Sandra C. Chapman;Joseph Spencer;Daniel J. Ratliff;Nigel P. Meredith;Thomas Elsden;Thomas Neukirch;David P. Hartley;Rachel Black;N. Watkins;S. Elvidge
准线性理论已被证明能很好地描述磁层、空间、天体物理和实验室等离子体“弱湍流”情景中的一系列输运现象。众所周知，当电磁波的振幅和增长率足够“小”，带宽足够“大”时，均匀背景场情况下的共振扩散准线性理论可以形式化地描述粒子动力学。然而，重要的是要注意，对于预期引起准线性输运的给定波谱，准线性理论确实可以适用于给定范围的共振俯仰角和能量，但可能不适用于一些更小或更大的共振俯仰角和能量值。也就是说，即使在均匀背景磁场的情况下，准线性理论的适用性也可以是俯仰角相关的。如果准线性理论确实适用，那么具有不同俯仰角的粒子的运动仍然具有不同的时间尺度。使用高性能的测试粒子代码，我们提出了一个详细的分析，准线性理论的适用性，以一系列不同的波谱，否则“出现准线性”，如果提出的，例如，卫星监测模式数据。我们提出这些分析作为波的振幅，波的相干性和共振粒子的速度（能量和俯仰角）的函数，并contextualise的结果使用理论的共振重叠和小振幅的标准。在这样做时，我们确定和分类五种不同的运输制度，是一个函数的粒子间距角。在我们的论文中的结果表明，可以有一个显着的各种粒子的响应（作为俯仰角的函数）非常相似的调查模式的电磁波产品，即使他们似乎满足所有适当的准线性标准。近年来，在这一领域出现了一系列非常有趣和重要的结果，我们主张继续努力：（一）新的运输理论的发展，以了解这些，和其他不同的电子响应的重要性;（二）这是由突发和调查模式的航天器数据之间的关系的统计分析。
Quasilinear theories have been shown to well describe a range of transport phenomena in magnetospheric, space, astrophysical and laboratory plasma “weak turbulence” scenarios. It is well known that the resonant diffusion quasilinear theory for the case of a uniform background field may formally describe particle dynamics when the electromagnetic wave amplitude and growth rates are sufficiently “small”, and the bandwidth is sufficiently “large”. However, it is important to note that for a given wave spectrum that would be expected to give rise to quasilinear transport, the quasilinear theory may indeed apply for given range of resonant pitch-angles and energies, but may not apply for some smaller, or larger, values of resonant pitch-angle and energy. That is to say that the applicability of the quasilinear theory can be pitch-angle dependent, even in the case of a uniform background magnetic field. If indeed the quasilinear theory does apply, the motion of particles with different pitch-angles are still characterised by different timescales. Using a high-performance test-particle code, we present a detailed analysis of the applicability of quasilinear theory to a range of different wave spectra that would otherwise “appear quasilinear” if presented by e.g., satellite survey-mode data. We present these analyses as a function of wave amplitude, wave coherence and resonant particle velocities (energies and pitch-angles), and contextualise the results using theory of resonant overlap and small amplitude criteria. In doing so, we identify and classify five different transport regimes that are a function of particle pitch-angle. The results in our paper demonstrate that there can be a significant variety of particle responses (as a function of pitch-angle) for very similar looking survey-mode electromagnetic wave products, even if they appear to satisfy all appropriate quasilinear criteria. In recent years there have been a sequence of very interesting and important results in this domain, and we argue in favour of continuing efforts on: (i) the development of new transport theories to understand the importance of these, and other, diverse electron responses; (ii) which are informed by statistical analyses of the relationship between burst- and survey-mode spacecraft data.