SOLARNET Conference: The Many Scales of the Magnetic Sun

Solar prominences consist of a thin thus low-collisional and partially ionized plasma.
Therefore, the coupling of ions and neutral atoms is much weaker than in photosphere,
and ions are affected by the Lorentz-force, while neutral atoms are not.
To investigate this issue, we performed simultaneous observations of the spectral lines
of several ions and neutral atoms with THEMIS at the Observatorio del Teide, Tenerife.
The selected spectral lines are optically thin, so that we probe also the inner part
of the prominence. We find that lines of ions are broadened compared to such from
neutral atoms, and Sr II 4216 is even broader than Fe II lines. Lines from neutral
metals (Mg I b2, Na I D1) appear broader than He I 5016, a line from the singlet
system. Doppler velocities also differ among the observed lines and show a typical
sequence. Probably the situation is more complicated than just having one ionized
and one neutral plasma component.