Magnetohydrodynamic wave as a tool for solar plasma diagnostics and heating

Magnetohydrodynamic (MHD) waves interact with the solar magnetic structures and have the potential to heat solar plasma and be used as a tool for plasma diagnostics. Despite extensive research, the precise mechanisms by which waves contribute to energy transport and dissipation remain incompletely understood. Additionally, utilizing wave characteristics for accurate diagnostics of the coronal plasma structure presents a significant challenge. Here, we utilize the Goode Solar Telescope to demonstrate transverse oscillations of the dark fibrils within the umbra of a sunspot and investigate their role in plasma heating. Additionally, we use EUV observations to show a quasi-periodic fast-mode MHD wave passing through a coronal hole could serve as a tool for plasma diagnostics. Our study finds that transverse oscillations are prevalent in the umbra of sunspots and carry a wave energy flux that significantly exceeds the loss rate of the solar active regions. Furthermore, the discovery of the MHD wave lensing effect provides a new mechanism for coronal hole diagnostics, with potential application to polar regions. These findings confirm the crucial role of MHD waves in coronal heating and demonstrate their potential as diagnostic tools for coronal plasma parameters. The studies provide new perspectives for understanding the multi-scale energy conversion and wave-magnetic field interactions in the solar atmosphere.