We estimate the role of heat flux from hot magnetic loops and open flux tubes into the surrounding corona as a possible source of heating of the corona. We show that hot magnetic-flux tubes (Type-II spicules) provide a more efficient source of coronal heating than hot magnetic loops, as the closed magnetic structure of a loop substantially restricts the heat flux into the corona. In order to compensate for radiation and thermal-conduction losses, approximately $10^{4}$ Type-II spicules with a temperature of several million Kelvin are required, which is about 1% of the number of spicules simultaneously observed on the solar disk. Our analysis shows that the principal source of energy that heats the coronal plasma is photospheric convection, which generates electric currents of about $10^{10}$ – $10^{12}$ A in magnetic loops and spicules. Dissipation of the currents increases significantly in the partially ionized plasma, i.e. when ion–atom collisions and the associated Cowling conductivity occur. This results in two important effects: heating of plasma in magnetic structures up to several million Kelvin, and ejection of hot plasma from open magnetic-flux tubes to the corona, replenishing the corona with hot plasma. The ejection of hot plasma results from the heating of the spicule foot-point by electric-current dissipation, which grows with a sporadic increase in the velocity of photospheric convection, for example, due to five-minute oscillations or the Rayleigh–Taylor instability. As a result, the rate of heating the photospheric foot-points of the spicules by ring currents exceeds radiation losses, which leads to a jump in the pressure gradient and the ejection of hot plasma into the corona from the open tips of the magnetic-flux tubes.

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日冕磁性结构热流加热日冕的可能性

我们估计了从热磁环和开放通量管进入周围日冕的热通量的作用，作为日冕加热的可能来源。我们表明，热磁通量管（II 型针状体）提供比热磁环更有效的日冕加热源，因为环的闭合磁结构基本上限制了进入日冕的热通量。为了补偿辐射和热传导损失，大约需要 10 美元 ^{4} 美元的温度为几百万开尔文的 II 型针状体，这大约是在太阳盘上同时观察到的针状体数量的 1%。我们的分析表明，加热日冕等离子体的主要能量来源是光球对流，它在磁环和针状体中产生大约 $10^{10}$ – $10^{12}$ A 的电流。部分电离等离子体中的电流耗散显着增加，即当发生离子-原子碰撞和相关的 Cowling 电导率时。这会导致两个重要的影响：将磁性结构中的等离子体加热到几百万开尔文，以及从开放的磁通管向电晕喷射热等离子体，用热等离子体补充电晕。热等离子体的喷射是由电流耗散加热针状体足点引起的，电流耗散随着光球对流速度的零星增加而增长，例如，由于五分钟的振荡或瑞利-泰勒不稳定性。结果，环流加热针状体光球足点的速率超过了辐射损失，