  Marked velocity excesses of ions relative to neutrals are obtained from two
time series of the neighboring emission lines He I 5015 and Fe II 5018 in a
quiescent prominence. Their Doppler shifts show time variations of
quasi-periodic character where the ions are faster than the neutrals 1.0 <
V_macro(Fe II)/V_macro(He I) < 1.35 in series-A and, respectively, <1.25 in
series-B. This 'ratio excess' confirms our earlier findings of a 1.22 ion
velocity excess, but the present study shows a restriction in space and time of
typically 5 Mm and 5 min.
  The ratio excess is superposed by a time and velocity independent 'difference
excess' -0.3 < V_macro(Fe II)-V_macro(He I) < +0.7 km/s in series-A (also
indicated in series-B). The high repetition rate of 3.9 sec enables the
detection of high frequency oscillations with several damped 22 sec periods in
series-A. These show a ratio excess with a maximum of 1.7. We confirm the
absence of a significant phase delay of He neutrals with respect to the Fe
ions.
