Collaborative Research: SHINE--Stochastic Particle Acceleration by Turbulence in Solar Flares

观测到的来自太阳耀斑和太阳高能粒子(SEP)的辐射表明存在非热粒子和非常热的等离子体。虽然人们普遍认为能量的来源是磁重联，但这些高能粒子的起源仍存在相当大的争议。根据新的观测(特别是来自RHESSI的高分辨率数据)，PI提出了大部分释放的能量最初被转化为等离子体湍流，然后湍流加速粒子并进一步加热等离子体。因此，该团队计划研究各向异性湍流、级联和衰减在太阳等离子体加速中的作用。他们计划使用超越简单MHD处理的精确色散关系来评估波-波和波-粒子相互作用。他们的目标是将这些结果合并到太阳耀斑模型中，以呈现可以通过观测测试的自洽的耀斑图景。斯坦福大学的Pi和他的同事们已经开发了数值代码来研究粒子加热、加速、运输和辐射。威斯康星州的Co-Pi和他的团队在磁等离子体湍流领域拥有丰富的专业知识，并开发了与研究相关的区域中的湍流处理代码。PI和他的同事们最近的工作表明，湍流可以解释新观测的许多特征。他们预计耀斑等离子体中会出现湍流，他们的模拟也证实了这一点。Co-PI在可压缩MHD湍流的理解方面也取得了进展。因此，斯坦福-威斯康星州的这个团队认为，结合湍流产生和演化的物理学，以及它与太阳等离子体的耦合，现在将使太阳耀斑模型的研究取得进展。斯坦福大学和威斯康星州PIS的互补专业知识可以提供在这一重要问题上取得突破所需的工具。这项研究预计将具有很强的教育性，不仅涉及两所大学的博士后研究员和研究生，还包括本科生。这项研究的结果将通过斯坦福大学哈斯公共服务中心的赞助在当地的教育和公共机构中公布。

The observed radiation from solar flares and solar energetic particles (SEPs) indicates the presence of nonthermal particles and very hot plasmas. While it is generally believed that the source of the energy is magnetic reconnection, the origin of these high energy particles is a matter of considerable debate. Based on new observations (notably high resolution data from RHESSI), the PIs have proposed that most of the energy released is initially converted into plasma turbulence, which then accelerates particles and heats the plasma further. This team thus plans to investigate the role of anisotropic turbulence cascade and damping in the acceleration of solar plasmas. They plan to use accurate dispersion relations that go beyond simple MHD treatments in their evaluation of wave-wave and wave-particle interactions. Their goal is to incorporate these results into a solar flare model to present a self-consistent picture of flares that can be tested by observations. The Stanford PI and his associates have developed numerical codes to study particle heating, acceleration, transport, and radiation. The Wisconsin Co-PI and his group have substantial expertise in the area of magnetic plasma turbulence and have developed codes for treating turbulence in the regimes relevant to the study. Recent work by the PI and his associates has shown that turbulence can explain many features of the new observations. They expect turbulence to be present in flare plasmas and their simulations confirm this. The Co-PI has also made progress in the understanding of compressible MHD turbulence. This Stanford-Wisconsin team thus believes that incorporating the physics of turbulence generation and evolution, and its coupling with solar plasma, will now permit advances in solar flare modeling. The complementary expertise of the Stanford and Wisconsin PIs could provide the tools necessary for a breakthrough in this important problem. This research is expected to have a strong educational aspect by involving not only postdoctoral fellows and graduate students at both institutions, but also undergraduate students. The results of this research will be presented at local educational and public institutions through the auspices of Stanford's Haas Center for Public Service.