The Sun frequently accelerates near-relativistic electron beams that travel out through the solar corona and interplanetary space. Interacting with their plasma environment, these beams produce type III radio bursts—the brightest astrophysical radio sources seen from Earth. The formation and motion of type III fine frequency structures is a puzzle, but is commonly believed to be related to plasma turbulence in the solar corona and solar wind. Combining a theoretical framework with kinetic simulations and high-resolution radio type III observations using the Low-Frequency Array, we quantitatively show that the fine structures are caused by the moving intense clumps of Langmuir waves in a turbulent medium. Our results show how type III fine structure can be used to remotely analyse the intensity and spectrum of compressive density fluctuations, and can infer ambient temperatures in astrophysical plasma, substantially expanding the current diagnostic potential of solar radio emission.

太阳经常加速穿过日冕和行星际空间的近相对论电子束。这些光束与它们的等离子体环境相互作用，产生 III 型射电暴——从地球上看到的最亮的天体物理射电源。III型精细频率结构的形成和运动是一个谜，但通常认为与太阳日冕和太阳风中的等离子体湍流有关。将理论框架与动力学模拟和使用低频阵列的高分辨率无线电 III 型观测相结合，我们定量地表明，精细结构是由在湍流介质中移动的朗缪尔波的强烈团块引起的。我们的结果显示了如何使用 III 型精细结构来远程分析压缩密度波动的强度和光谱，