Does magnetic reconnection have a characteristic scale in space and time?

地球不断地被不断膨胀的太阳大气层（称为太阳风）所包围，太阳大气层携带着带电粒子（等离子体）和太阳磁场。地球自身的磁场延伸到太空中，保护我们免受太阳风的影响，形成了一个被称为磁层的空腔。一个被称为磁重联的过程允许太阳的磁场与地球的磁场连接，导致粒子和能量从太阳风转移到磁层。其中一些粒子可能会沿着地球的磁场线行进并撞击大气层，导致大气层发出被称为极光（通常称为北方光）的光。事实上，磁场重联是地球磁层中最重要的输运过程。还有令人信服的观测证据表明，磁场重联过程发生在太阳表面附近的大气层（日冕），磁场重联可能对理解恒星的形成、宇宙射线的起源（来自太空的高能粒子）、吸积盘（在恒星、星系和黑洞周围发现）以及行星、恒星和星系中磁场的产生很重要。在更近的地方，理解和控制磁重联对核聚变反应堆的发展至关重要。虽然对磁重联过程有了基本的了解，但它究竟是如何、在哪里以及何时发生的仍然不清楚。最近对磁层中等离子体流动和电流以及极光增亮的观测提供了无标度行为的证据，即这些量的波动没有典型的大小，可以在很大范围内看到。这种行为是分形的典型特征，在自然界中经常可以看到，例如海岸线的形状和雪崩的大小。这些无标度的观测反过来又促进了磁重联本身是无标度的想法。然而，没有直接证据证明这一点，这与传统的磁重联过程的理解相反。英国南极调查局的研究人员开发了一种遥感磁层磁场重联的新技术，将航天器和地面极光成像仪的观测与称为SuperDARN（超级双极光雷达网）的雷达网结合起来使用。我们将使用这种技术在很宽的尺度范围内对空间和时间上的磁重联结构进行统计分析。通过这样做，我们将测试的假设，磁重联是无标度的，并提供了一个新的多尺度磁重联模型的约束。

The Earth is continually enveloped by the expanding atmosphere of the Sun (known as the solar wind) that carries with it charged particles (plasma) and the Sun's magnetic field. The Earth's own magnetic field, extending into space, protects us from this solar wind, forming a cavity known as the magnetosphere. A process known as magnetic reconnection allows the Sun's magnetic field to connect to that of the Earth leading to the transfer of particles and energy from the solar wind into the magnetosphere. Some of these particles may travel along the Earth's magnetic field lines and strike the atmosphere, causing it to give off light in displays known as the aurora (commonly known as the northern lights). In fact, magnetic reconnection is the most significant transport process in the Earth's magnetosphere. There is also compelling observational evidence that magnetic reconnection processes take place in the Sun's atmosphere near its surface (the solar corona) and magnetic reconnection may be important for understanding the formation of stars, the origin of cosmic rays (high energy particles coming from space), accretion disks (found around stars, galaxies and black holes), and the generation of magnetic fields in planets, stars and galaxies. Closer to home, understanding and controlling magnetic reconnection is vital in the development of nuclear fusion reactors. Whilst there is a basic understanding of the magnetic reconnection process, exactly how, where, and when it occurs is still not understood. Recent observations of plasma flows and electric currents in the magnetosphere and of brightenings in the aurora, have provided evidence of scale-free behaviour i.e. that fluctuations in these quantities do not have a typical size and are seen across a wide range of sizes. This behaviour is typical of fractals and is often seen in nature such as in the shape of coastlines and the size of snow avalanches. These scale-free observations have, in turn, promoted the idea that magnetic reconnection is itself scale-free. However, there is no direct evidence for this and it is contrary to the traditional understanding of the magnetic reconnection process. Researchers at the British Antarctic Survey have developed a new technique to remotely sense magnetic reconnection in the magnetosphere using a combination of observations made from spacecraft and on the ground with auroral imagers and a radar network known as SuperDARN(the Super Dual Auroral Radar Network). We will use this technique to characterise statistically the structure of magnetic reconnection in both space and time over a wide range of scales. By doing this we will test the hypothesis that magnetic reconnection is scale-free and provide a constraint for new multi-scale magnetic reconnection models.