Dynamical evolution of magnetic flux ropes in the solar wind

The conservation of magnetic flux in systems of very low dissipation, as the interplanetary medium, is used to analyze magnetic clouds in significant expansion. In particular, we analyze the fast and huge event observed at one astronomical unit in the solar wind on Nov. 9-10, 2004. We compare magnetic and velocity observations to two self-similar and free expansion models that allow us to correct the mixing spatial-variation/time-evolution observed in situ by the spacecrafts. As magnetic clouds are astrophysical objects that transport a very important amount of magnetic flux and helicity from the Sun to the interplanetary medium, we compare the values of these global quantities obtained using the present models with those values coming from the commonly used static Lundquist's model.