Confinement of hot, hard X-ray producing electrons in solar flares
Confinement of hot, hard X-ray producing electrons in solar flares
复制标题
太阳耀斑中产生热硬 X 射线的电子的限制
DOI：
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发表时间：
1979
期刊：
影响因子：
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通讯作者：
C. Lilliequist
中科院分区：
文献类型：
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作者：
D. Smith;C. Lilliequist
研究了太阳硬X射线辐射的可能的热模型，其中包括电子被快速加热到4×10/sup 8/K的小体积，以确定在什么条件下这种模型比非热模型更有效。在这些模型中，主要的能量损失机制是热传导引起的源膨胀，通过对这些机制的综述和系统化，使其偏离了经典的值。一种这样的机制是热通量在其最大可能值饱和，对应于电子的直接对流。另一种机制是由于回流电流的不稳定而导致热通量的异常限制，回流电流必须补偿携带热量的电子电流。分析了一个简单的一维模型，在该模型中，一段恒定密度的通量管被加热到4×10/sup 8/K。由上述无碰撞过程确定的传导前沿沿膨胀源头部的通量管移动。建立了一种更真实的一维一流体两温度模型，该模型具有时空变化的能量源，能量以有限的速率传递给电子。这导致了一些离子加热和质量运动，而这些运动本身只代表了很小的能量损失。然而，随着离子温度的升高，热流密度的反常极限发生变化，膨胀损失显著增加。《更少》
Possible thermal models for solar, hard X-ray emission, consisting of small volumes in which the electrons are rapidly heated to 4 x 10/sup 8/ K, are examined to determine under what conditions such models can be more efficient than nonthermal models. The primary energy-loss mechanism in these models is source expansion due to heat conduction which deviates from its classical value by mechanisms which are reviewed and systematized. One such mechanism is saturation of the heat flux at its maximum possible value, corresponding to direct convection by electrons. Another mechanism is anomalous limitation of the heat flux due to instability of the return current which must compensate the electron current carrying the heat. A simple, one-dimensional model in which a section of the flux tube of constant density is heated to 4 x 10/sup 8/ K is analyzed. A conduction front, determined by the above collisionless process, moves along the flux tube at the head of the expanding source. A more realistic, one-dimensional, one-fluid, two-temperature model with a spatially and temporally varying energy source which delivers energy to the electrons at a finite rate is formulated and solved numerically. This results in some ion heating and mass motions which, by more » themselves, represent only a small energy loss. However, because of changes in the anomalous limitation of the heat flux with higher ion temperature, the expansion losses increase considerably. « less