On transient electric fields observed in chemical release experiments by rockets

As a follow‐up to the successful chemical release experiment Trigger in 1977, the Trigger Optimized Repetition rocket was launched from Esrange on October 24, 1984. As in the Trigger experiment, a large‐amplitude electric field pulse of 200 mV/m was detected shortly after the explosion. The central part of the pulse was found to be clearly correlated with an intense layer of swept up ambient particles behind a propagating shock front. The field was directed toward the center of the expanding ionized cloud, which is indicative of a polarization electric field source. Expressions for this radial polarization field and the much weaker azimuthal‐induced electric field are derived from a simple cylindrical model for the field and the expanding neutral cloud. Time profiles of the radial electric field are shown to be in good agreement with observations.