Joan Jordi Boldu O Farrill Treviño (Uppsala University/IRF): Probing the solar wind evolution with kinetic waves (Licentiate)

Tuesday 5 Dec 2023, 13:00 → 14:00 Europe/Stockholm

Title: Probing the solar wind evolution with kinetic waves
Speaker: Joan Jordi Boldu O Farrill Treviño
Affiliation: Uppsala University/IRF
Time: Thursday 5 December 2023, 1300 to 1400
Location: 10132Å Häggsalen (https://link.mazemap.com/T0Wnxt61)
Opponent: Prof. Herbert Gunell from Umeå University

Abstract: Charged particles constantly stream outward from the Sun to fill the solar system. These particles, consisting mainly of protons and electrons, form a plasma called the solar wind. The solar wind interacts with every celestial body in the solar system, giving rise to different phenomena, such as the auroras observed at high latitudes on Earth or disruption of the systems onboard artificial satellites.

The general structure of the solar wind has been established several decades ago, however, we still do not fully understand how the solar wind properties, like temperature and velocity distribution, evolve as it propagate outward in the solar system. Observations of these properties cannot be explained from a conventional fluid description. In a system approximated as a fluid, particle collisions dictate its thermodynamic state. However, the solar wind is a weakly collisional plasma that deviates from thermodynamic equilibrium. Therefore, the radial evolution of the solar wind properties must be driven by different processes. In particular, wave-particle interactions are an important regulator of the solar wind properties, because of the strong connection between the electromagnetic fields and the charged particles.

In this thesis, we probe how the velocity distribution of solar wind particles evolves as it travels from the Sun to the Earth. Specifically, we study the contribution of waves on the observed solar wind properties at different distances and how these waves can affect the interplanetary environment. We focus on two types of plasma waves frequently observed in the solar wind, Langmuir and ion-acoustic waves. We present their occurrence rates at different heliocentric distances and suggest wave generation mechanisms based on Solar Orbiter observations.