Correlaciones entre distribuciones kappa y parámetro de colisión en la magnetósfera terrestre.

Abstract

Using data collected by the THEMIS mission from 2007 to 2012, we have investigated possible correlations between the Kappa index (κ) and a collision parameter (ξcol) in the protons that make up the magnetosphere. Our research aims to validate the proposed hypothesis that particle collisions play a crucial role in the thermalisation of the plasma, leading to the observation of Maxwellian-type distributions. We expected that the collision rate could influence the presence or absence of highenergy-tail kappa distributions in the Earth’s magnetosphere. Using the energy flux data, we fitted kappa-type distributions. In addition, we introduced a new parameter, the collision frequency ratio, which depends on the background magnetic field, particle density and temperature. However, the results obtained showed significant discrepancies from our initial expectations. Contrary to our hypothesis, we observed that in the magnetosphere a higher collision rate is strongly associated with low values of the kappa index, indicating high-energy tails. On the other hand, lower values of the collision frequency ratio seem to be associated with higher Kappa values, behaving like Maxwellian distributions. These results challenge our expectations and raise new questions about the role of collisions in the Earth’s magnetosphere.