Low-frequency fluctuations are pervasively observed in the solar wind. The present paper theoretically calculates the steady state spectra of low-frequency electromagnetic (EM) fluctuations of the Alfvénic type for thermal equilibrium plasma. The analysis is based upon a recently formulated theory of spontaneously emitted EM fluctuations in magnetized thermal plasmas. It is found that the fluctuations in the magnetosonic mode branch is constant, while the kinetic Alfvénic mode spectrum is dependent on a form factor that is a function of perpendicular wave number. Potential applicability of the present work in the wider context of heliospheric research is also discussed.
低频涨落普遍存在于太阳风中。本文从理论上计算了热平衡等离子体中阿尔文型低频电磁涨落的稳态谱。分析基于最近提出的磁化热等离子体中自发电磁涨落理论。研究发现，磁声波分支的涨落谱为常数，而动力学阿尔文波分支的谱依赖于垂直波数的形状因子。本文还讨论了该工作在更广泛日球层研究中的潜在应用。