DC ELECTRIC-FIELD MEASUREMENTS WITH THE GUARA SPREAD-F ROCKET

Data presented in this paper provide the first high-altitude (> 600 km ) rocket measurements of electric fields associated with spread-F plum es measured simultaneously with a VHF coherent backscatter radar. In r egions outside of spread-F plasma depletions the electric field is pri marily vertical, implying zonal plasma flow. The mean zonal drifts of the ambient plasma-inferred from the rocket data are larger than avera ge quiet time values, which can be attributed to the presence of activ e spread-F irregularities. Within the spread-F depletions, the vertica l electric field becomes comparable to the zonal component, and indivi dual plasma depletions are found to rise with speeds of up to 100 m/s. No large (> 10 mV/m) electric fields are observed in the plume region .