  Even quiescent solar prominences may become active and sometimes erupt. These
events are occasionally linked to coronal mass ejections. However we know very
little about the plasma properties during the activation and eruption
processes. We present new computations of the helium line profiles emitted by
an eruptive prominence. The prominence is modelled as a plane-parallel slab
standing vertically above the solar surface and moving upward as a solid body.
The helium spectrum is computed with a non local thermodynamic equilibrium
radiative transfer code. The effect of Doppler dimming / brightening is
investigated in the resonance lines of He I and He II formed in the EUV, as
well as on the He I 10830 A and 5876 A lines. We focus on the line profile
properties and the resulting integrated intensities. It is shown that the
helium lines are very sensitive to Doppler dimming effects. We also study the
effect of frequency redistribution in the formation mechanisms of the resonance
lines and find that it is necessary to use partial redistribution in frequency
for the resonance lines.
