Abstract

The process of the rise and development of low-frequency instability of kinetic Alfven waves (KAW) and kinetic ion-acoustic waves (KIAW) in preflare solar plasma near the footpoints of magnetic loops, i.e., in the area that corresponds to the height of low-middle chromosphere, has been studied. The observational data obtained in the framework of international missions Hinode, SDO, and IRIS demonstrate that a magnetic field’s amplitude can vary in the interval from a few dozen up to few hundred gausses. The existence of large-scale weak electric fields (“sub-Dreicer” in generally accepted terminology) during a long enough time (with respect to the time of instability development) can be considered in the framework of the used concept as the main source of the wave generation. One more source of instability is slow drift motions of plasma, which are the result of spatial inhomogeneties of temperature and density of a medium. Our former investigations of the obtained solutions of dispersive relation for low-frequency kinetic waves, which are generated due to the development of correspond instabilities, have established an important fact: for some semiempirical models of the solar atmosphere, the kinetic waves generated during the linear stage of the development are members of the family of kinetic Alfven waves and the family of kinetic ion-acoustic waves. It has been proven that the considered wave generation can take place in plasma with pure Coulomb conductivity as well as in plasma with saturated, small-scale Bernstein turbulence. The latter can appear in the investigated area as result of natural evolution of instability of the first harmonics of quasi-Bernstein modes. This mode has much lower threshold with respect to the amplitude of a sub-Dreicer field than low-frequency kinetic waves. Besides this fact, the waves considered have a low enough degree of plasma nonisothermality, which is needed for the appearance of instability. The principal possibility for excitation of nondamped kinetic waves with small amplitudes in the area under investigation has also been proven. It is very important for the increase in the probability for realization of the process of three-wave interaction and appearance of the spikes of microwave emission in the preflare state of the active region and, correspondingly, for making the combined short-term prediction of a flare in it.

中文翻译：

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有源区火炬过程早期电磁回路等离子体中的低频动波

摘要

在耀斑前太阳等离子体中，在磁环脚附近（即在对应于高度的区域中）的动力学Alfven波（KAW）和动力学离子声波（KIAW）低频不稳定性的上升和发展过程。低中度色球层，已经被研究过。在国际任务Hinode，SDO和IRIS的框架中获得的观测数据表明，磁场的振幅可以在几十至数百高斯的区间内变化。可以在使用的概念的框架内考虑在足够长的时间内（相对于不稳定的发展时间）存在大范围的弱电场（在普遍接受的术语中为“次降噪器”）。波的产生。不稳定的另一个原因是等离子体的缓慢漂移运动，这是温度和介质密度在空间上不均匀的结果。我们以前对低频动波的色散关系的解的解决方案的研究，是由于相应的不稳定性的发展而产生的，它已经建立了一个重要的事实：对于太阳大气的某些半经验模型，线性过程中产生的动波发展的阶段是动力学阿尔夫文波家族和动力学离子-声波家族的成员。已经证明，可以在具有纯库仑电导率的等离子体中以及在具有饱和小尺度伯恩斯坦湍流的等离子体中发生所考虑的波。后者可能是拟伯恩斯坦模的一次谐波的不稳定性的自然演化的结果。该模式相对于次Dreicer场的振幅具有比低频动波低得多的阈值。除此事实外，所考虑的波具有足够低的等离子体非等温度，这对于出现不稳定性是必需的。还证明了在研究区域内激发振幅较小的非阻尼动波的主要可能性。这对于提高实现三波相互作用过程的可能性以及在有源区域的前耀斑状态下出现微波发射的尖峰的可能性非常重要，并且相应地，对于组合的短期预测也非常重要。耀斑。所考虑的波具有足够低的等离子非等温度，这是出现不稳定所必需的。还证明了在研究区域内激发振幅较小的非阻尼动波的主要可能性。这对于提高实现三波相互作用过程的可能性以及在有源区域的前耀斑状态下出现微波发射的尖峰的可能性非常重要，并且相应地，对于组合的短期预测也非常重要。耀斑。所考虑的波具有足够低的等离子体非等温度，这对于出现不稳定现象是必需的。还证明了在研究区域内激发振幅较小的非阻尼动波的主要可能性。这对于增加实现三波相互作用过程的概率以及在有源区域的前耀斑状态下出现微波发射的尖峰的可能性非常重要，并且相应地，对于组合的短期预测也非常重要。耀斑。