Collaborative Research: Electron Heat Flux Regulation in the Solar Wind

了解和描述日光层内和整个宇宙中发生的基本过程是重要的，这对于未来人类探索空间以及研究空间环境对现代文明的影响可能至关重要。太阳风是有害辐射传播的媒介。对太阳风的准确描述对于理解这些扰动从太阳到地球的传播是必要的。该项目研究太阳风物理学。这项工作支持培养一名研究生和博士后研究人员。这项研究旨在解决“是什么调节了太阳风热通量？“太阳风中的电子有效地传导热量，从而沿着逆太阳方向沿着携带热通量。在调节热通量的物理过程中，哨声热通量不稳定性被认为在无碰撞热通量区是重要的，而在碰撞区，二元碰撞是经典的调节机制。这两个过程都与径向膨胀效应相竞争。这些竞争过程的相对重要性，即不稳定性，碰撞和膨胀，仍然是一个突出的，因此，它们共同构成了一个引人注目的研究课题。该项目将利用磁化等离子体中自洽准线性理论和碰撞动力学理论，模拟径向变化的太阳风中波和电子热通量的演变。这一理论将由来自各种航天器的、经过良好校准的太阳风电子分布函数测量数据以及质子参数、磁场和等离子体波数据的输入数据驱动，并将对照这些数据进行检验，这些数据来自0.3至1 Au的各种航天器。这种对太阳风电子及其携带的热通量性质的综合和合作研究将大大有助于提高我们对日光层内发生的基本过程的理解。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Understanding and characterizing fundamental processes that take place within the heliosphere and throughout the universe is important, and it could be vital for future human explorations of space, as well as for studying the space environmental impact on modern civilization. Solar wind is the medium through which harmful radiation travels. An accurate description of the solar wind is necessary to understand the propagation of these disturbances from the Sun to the Earth. This project studies solar wind physics. The work supports training of a graduate student and post-doctoral researcher.The research aims to address the compelling science question of "what regulates the solar wind heat flux?" The electrons in the solar wind efficiently conduct heat, thus carrying the heat flux along the anti-sunward direction. Among physical processes that regulate the heat flux, whistler heat-flux instabilities are suggested as being important in the collisionless heat flux regime, while in the collisional regime, the binary collisions are the classical regulation mechanism. Both processes compete against the radial expansion effects. The relative importance of these competing processes, that is, instabilities, collisions, and expansion, remains an outstanding and thus, together they constitute a compelling research topic. The project will use the self-consistent quasilinear theory and kinetic theory of collisions in magnetized plasma to model the evolution of the waves and electron heat flux in the radially-varying solar wind. The theory will be driven by inputs from, and tested against, the well-calibrated measurements of the solar wind electron distribution function from various spacecraft between 0.3 and 1 AU, as well as proton parameters, magnetic field and plasma wave data. Such an integrated and collaborative research on the nature of solar wind electrons and the heat flux they carry will greatly contribute toward improving our understanding of the fundamental processes that take place within the heliosphere.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.