Why is the Pot warmer than the Stove

5 Jan 2022

At https://phys.org/news/2022-01-liquid-metal-insight-mechanism-sun-corona.... ... the phenomenon of corona heating remains one of the mysteries of solar physics, it is said. Why is the pot warmer than the stove? The corona reaches temperatures of several million degrees celsius. Assessing a hot trail to explain the effect leads to just below the corona where plasma waves travel at the same speed as sound waves. In an experiment using molten alkali metal, rubidium, and pulsed magnetic fields, a German team has developed a model, and experimentally confirmed the theoretically predicted behaviour of plasma waves [Alfven waves to be exact] according to a study published in Physical Review Letters, this week. It is now established that magnetic fields play a dominant role in feeding the sun's corona. However, it is controversial as to how or why that happens. Is it due to changes in magnetic field directions, for example, or is it due to dampening? It doesn't  mention the role of electricity, as part of the process, but the team explored Alfven waves - which are ionised. The frequency and propagation of Alfven waves increased with the strength of the magnetic field.

It goes on to describe the experiment and its implications, as well as the problems setting it up. Further experiments are planned. Meanwhile, the Parker Solar Probe and the Solar Orbiter probe. are expected lp p[roduce further inofrmation. See https://doi.org/10.1103/PhysRevLett.127.275001                                                               ,