THE MULTI-SPECIES FARLEY–BUNEMAN INSTABILITY IN THE SOLAR CHROMOSPHERE
THE MULTI-SPECIES FARLEY–BUNEMAN INSTABILITY IN THE SOLAR CHROMOSPHERE
复制标题
太阳色球中的多物种法利-布内曼不稳定性
DOI：
10.1088/0004-637x/783/2/128
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
J. Fontenla
中科院分区：
文献类型：
--
作者：
C. Madsen;Y. Dimant;M. Oppenheim;J. Fontenla
太阳色球层的经验模型显示强烈的电子加热刚好高于其温度最低值。电阻耗散和冲击波等机制似乎不足以解释从紫外线和连续测量中推断出的这种加热的持久性和均匀性。本文进一步发展了Farley-Buneman不稳定性（FBI）理论，该理论可能对这种加热有很大贡献。它扩展了Fontenla提出的单离子理论，开发了一种多离子物种的方法，可以更好地模拟太阳色球层中以金属为主的离子等离子体。该分析产生线性色散关系，该线性色散关系预测触发不稳定性所需的临界电子漂移速度。使用碰撞频率的仔细估计和色球层的一维半经验模型，这一新理论预测，不稳定性可能由低至4 km s-1的速度触发，远低于中性声速。在地球电离层中，FBI经常发生在不稳定触发速度显著超过中性声速的情况下。由此，我们预计从光球层上升的中性流具有足够的能量，可以很容易地产生电场和具有足够幅度的电子霍尔漂移，使FBI在色球层中很常见。如果是这样的话，这个过程将提供一种机制，将中性流和湍流能量转化为安静太阳中的电子热能。
Empirical models of the solar chromosphere show intense electron heating immediately above its temperature minimum. Mechanisms such as resistive dissipation and shock waves appear insufficient to account for the persistence and uniformity of this heating as inferred from both UV lines and continuum measurements. This paper further develops the theory of the Farley–Buneman instability (FBI) which could contribute substantially to this heating. It expands upon the single-ion theory presented by Fontenla by developing a multiple-ion-species approach that better models the diverse, metal-dominated ion plasma of the solar chromosphere. This analysis generates a linear dispersion relationship that predicts the critical electron drift velocity needed to trigger the instability. Using careful estimates of collision frequencies and a one-dimensional, semi-empirical model of the chromosphere, this new theory predicts that the instability may be triggered by velocities as low as 4 km s-1, well below the neutral acoustic speed. In the Earth's ionosphere, the FBI occurs frequently in situations where the instability trigger speed significantly exceeds the neutral acoustic speed. From this, we expect neutral flows rising from the photosphere to have enough energy to easily create electric fields and electron Hall drifts with sufficient amplitude to make the FBI common in the chromosphere. If so, this process will provide a mechanism to convert neutral flow and turbulence energy into electron thermal energy in the quiet Sun.