Charge state distributions of heavy solar wind ions measured in interplanet
ary space can be used to probe the physical conditions in the solar corona.
This paper presents a study of the charge state distributions and the magn
etic topology of 56 coronal mass ejections (CMEs) observed in interplanetar
y space by the Ulysses spacecraft. The analysis of the data from the Solar
Wind Ion Composition Spectrometer (SWICS) instrument and the Vector Helium
Magnetometer (VHM) experiment onboard Ulysses shows a clear correlation bet
ween the charge state distributions and the magnetic topology of CMEs. Almo
st all CMEs whose charge state distributions are shifted to higher charge s
tates with respect to the ambient solar wind have the structure of magnetic
clouds, whereas CMEs with the same charge state distributions as the surro
unding solar wind do not show magnetic cloud structure. This correlation is
found for CMEs observed at low, mid, and high solar latitudes. On the basi
s of the numerical solution of the ionization/recombination equations for o
xygen and silicon, it is investigated which changes of the electron tempera
ture, electron density, and the speed of the ions in the source region of t
he CMEs can reproduce the observations. It is shown that the main reason fo
r the observed enhancement of higher charge states in the cloud CMEs is an
increased electron temperature. However, the evolution of the density and v
elocity of the CMEs before the charge states freeze in cannot be neglected.