Spectral diagnostic of active prominences

Active prominences exhibit plasma motions, resulting in difficulties with the interpretation of spectroscopic observations. As they are under the strong influence of radiation coming from the solar disk, Doppler dimming or brightening effects may arise, depending on which lines are observed and on the velocity of the plasma. Interlocking between the different atomic energy levels and non local thermodynamic equilibrium lead to non-trivial spectral line profiles, and this calls for complex numerical modelling of the radiative transfer in order to understand the observations. We present such a tool, which solves the radiative transfer and statistical equilibrium for H, He I, He II, and Ca II, in moving prominences where radial plasma motions are taking place. The powerful diagnostic capabilities of a combination of lines emitted by these elements will be demonstrated.