CRIT II electric, magnetic, and density measurements within an ionizing neutral stream

Measurements from rocket borne sensors inside a high velocity neutral barium beam show a factor of six increase in plasma density in a moving ionizing front. This region was co‐located with intense fluctuating electric fields (δE ≈ 300 mV/m) at frequencies well under the lower hybrid frequency for a barium plasma. Large quasi‐DC electric and magnetic field fluctuations were also detected with a large component of the current and the electric field parallel to B o . An Alfvén wave with a finite electric field component parallel to the geomagnetic field was observed to propagate along B o , where it was detected by an instrumented sub‐payload.