论文标题
圆柱喷气机的有效加速：辐射冷却和纠结磁场的影响
Efficient acceleration of cylindrical jets: effects of radiative cooling and tangled magnetic field
论文作者
论文摘要
与De Laval喷嘴一样，发散的超音速流正在加速，并且已经将同样的概念用于宇宙中磁性流动流动的加速。在这里，我们研究了“不变”圆柱超音速流的动力学，并表明它们可以通过辐射冷却和纠结磁场的影响来加速它们。根据我们对Pulsar风星脉冲的研究，还配合了喷射材料的辐射冷却（冷却效果），将有序磁场转化为湍流磁场（转换效果）和湍流磁场的耗散（耗散效果）。尽管每种冷却和转化效应都是一个无效的加速过程，但是当冷却，转换和耗散效应同时起作用时，磁化圆柱喷头的末端速度约为最大值可能值的一半。在最大加速度的情况下，辐射效率也约为射流总亮度的一半。非理想MHD效应流动加速的概念可能有助于研究活跃银河核中的相对论喷射，其中预计射流轴附近的区域将是圆柱形和扭结不稳定的。
Diverging supersonic flows are accelerating, as in the case of a de Laval nozzle, and the same concept has been applied for acceleration of magnetohydrodynamic flows in the universe. Here, we study the dynamics of "non-diverging" cylindrical supersonic flows and show that they can be accelerated by effects of radiative cooling and the tangled magnetic field. In addition to radiative cooling of the jet materials (cooling effect), conversion of the ordered magnetic field into the turbulent one (conversion effect) and dissipation of the turbulent magnetic field (dissipation effect) are formulated according to our study on pulsar wind nebulae. Although each of the cooling and conversion effects is an ineffective acceleration process, the terminal velocity of magnetized cylindrical jets attains about half of the maximum possible value when the cooling, conversion and dissipation effects work simultaneously. The radiation efficiency is also about half of the total luminosity of the jet in the case of maximal acceleration. The concept for flow acceleration by the non-ideal MHD effects may be useful for studying relativistic jets in active galactic nuclei, in which the region near the jet axis is expected to be cylindrical and kink unstable.
