非局部热输运在耀斑驱动的色球蒸发中的作用
The Role of Non-local Thermal Transport in Flare-Driven Chromospheric Evaporation
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中文总结 AI 辅助
该研究通过MHD模拟比较三种热传导模型，发现非局部SNB模型能更真实地模拟耀斑加热后的色球蒸发，为下一代太阳耀斑模拟提供可行方案。
中文摘要 AI 辅助
热传导在太阳耀斑期间的能量输运中起着重要作用。耀斑将太阳大气加热至数千万开尔文，加上平均自由程超过1兆米，可导致热通量变为非局部的。我们使用磁流体力学Lare2d代码模拟了一次重联加热事件，采用了三种不同的热传导模型：沿磁场的经典Spitzer-Harm（SH）模型、带有热通量限制器（FL）的局部输运模型，以及非局部的Schurtz、Nicolai、Busquet（SNB）模型，后者常用于激光等离子体代码中，并已与完整的Vlasov-Fokker-Planck处理进行了基准测试。我们比较了使用每种模型的模拟中加热后大气层的演化。由于热通量受到抑制，SNB产生的峰值温度显著高于SH。此外，使用SNB输运时，色球蒸发发生较晚，且具有更强的极紫外发射强度。FL模拟的温度演化和色球蒸发与SNB相似，但不同的通量限制器值分别对峰值温度、下流速度和极紫外发射强度效果最佳，因此不存在对所有情况都最优的单一值。我们得出结论，SNB模型提供了一种在MHD尺度上纳入非局部热输运的可行方案，这对于提高下一代太阳耀斑模拟的真实性和准确性至关重要。
英文摘要
Thermal conduction plays an important role in energy transport during solar flares. Flares heat the solar atmosphere to tens of MK which, combined with mean free paths in excess of 1Mm, can cause the heat flux to become non-local. We use the magnetohydrodynamic Lare2d code to simulate a reconnective heating event with three different thermal conduction models: classical Spitzer-Harm (SH) along the magnetic field, local transport with a heat flux limiter (FL), and the non-local Schurtz, Nicolai, Busquet (SNB) model which is routinely used in laser-plasma codes and has been bench- marked against full Vlasov-Fokker-Planck treatment. The evolution of the atmosphere post heating is compared between simulations using each of these models. Due to a supressed heat flux, SNB gives rise to significantly higher peak temperatures than SH. Further, with SNB transport chromospheric evaporation occurs later and has stronger extreme ultraviolet emission intensity. FL simulations have similar temperature evolution and chromospheric evaporation to SNB, however different values of the flux limiter work best for peak temperature, downflow velocity and EUV emission intensity, and so there is no one optimal value for all cases. We conclude that the SNB model provides a practicable solution to incorporate non-local thermal transport at MHD scales, which will be crucial to improve the realism and accuracy of the next generation of solar flare simulations.
发表机构
- University of Warwick（华威大学）
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