Plasma flow pulsations in earth's magnetic tail

On November 9, 1972 Imp 7 was in the plasma sheet from 0430 to 1000 UT and detected strong earthward plasma flows. A series of nine temporal pulsations were observed to vary in bulk speed from 0 to about 1500 km/s and to occur at 15-30 minute intervals. A positive correlation exists between the speed variations and changes in the standard deviation of the magnetic field. Evident periodicity was not found corresponding to Imp 7 pulsations and other magnetospheric or solar wind data. It is felt that the pulsations may indicate that tail reconnection is unsteady in periods of 10-30 minutes.