标题： 太阳发电机理论中的未解问题 显示英文标题

标题： Outstanding Issues in Solar Dynamo Theory

摘要： 太阳的磁活动，表现为黑子周期，在其对流层深处通过一种涉及等离子体和磁场之间非平凡相互作用的发电机机制产生。 磁流体动力学发电机理论的最新进展使我们更接近于更好地理解太阳磁场周期的物理机制。 同时，对太阳内部大尺度流动的日震观测现在使得可以限制一些用于太阳周期模型的参数。 在本综述的第一部分，我简要描述了目前对太阳周期的理解状况。 在第二部分，我强调了一些与发电机$\alpha$-效应、磁场浮力以及活动性类似蒙德极小期的起源相关的太阳发电机理论中的关键问题。 我还讨论了对诸如湍流扩散、纬向环流和湍流通量泵送等关键物理过程的约束不足如何混淆了这些过程在磁通量传输中的相对作用。 我认为，除非解决其中一些问题，否则任何太阳周期模型都不能声称是“标准模型”，也不能信任这些模型的预测；换句话说，我们仍未达到这一目标。 显示英文摘要

摘要： The magnetic activity of the Sun, as manifested in the sunspot cycle, originates deep within its convection zone through a dynamo mechanism which involves non-trivial interactions between the plasma and magnetic field in the solar interior. Recent advances in magnetohydrodynamic dynamo theory have led us closer towards a better understanding of the physics of the solar magnetic cycle. In conjunction, helioseismic observations of large-scale flows in the solar interior has now made it possible to constrain some of the parameters used in models of the solar cycle. In the first part of this review, I briefly describe this current state of understanding of the solar cycle. In the second part, I highlight some of the outstanding issues in solar dynamo theory related to the the nature of the dynamo $\alpha$-effect, magnetic buoyancy and the origin of Maunder-like minima in activity. I also discuss how poor constraints on key physical processes such as turbulent diffusion, meridional circulation and turbulent flux pumping confuse the relative roles of these vis-a-vis magnetic flux transport. I argue that unless some of these issues are addressed, no model of the solar cycle can claim to be ``the standard model'', nor can any predictions from such models be trusted; in other words, we are still not there yet.