Measurements of electron beam and neutral gas emissions in a space plasma during an ionospheric modification experiment.

摘要

The principal objective of this research was to investigate observations of current collection enhancements due to nitrogen gas emissions from a highly charged, isolated rocket payload in the ionosphere. These observations were made during the second Cooperative High Altitude Rocket Gun Experiment (CHARGE-2) which was an electrically tethered dual payload system. The current collection enhancement was observed on a "daughter" payload located 100 to 426 m away from a "mother" payload, approximately perpendicular to the Earth's magnetic field, which was firing a 1 keV electron beam at up to 48 mA. The unambiguous response of emitting neutral gas from a highly charged vehicle located well away from the disturbed region surrounding the electron beam's mother payload was unique to this experiment.; These results are interpreted in terms of neutral gas ionization in close proximity to the daughter vehicle during the short periods of gas emission. The gas source was a modified nitrogen gas rate control system (RCS). The ionization source was most likely accelerated ionospheric electrons. The results indicate that it is possible to enhance the electron current collection capability of positively charged vehicles and reduce overall charging potentials by means of deliberate neutral gas release into a space plasma. Calculations also seem to suggest that ion current out of the ionization region was not a dominant factor in net current balance.; A secondary research objective was to investigate magnetic field-aligned electron beam ionization of the atmosphere using ground based vhf radar. Only one radar event could be correlated with both electron beam emission and expected range. This occurred during an RCS induced current collection enhancement which was itself unique among all RCS gas releases. During this event a high voltage power supply, connected in series between the mother payload and the tether wire to the daughter payload, drove the electron beam emitting payload several hundred volts negative with respect to the surrounding plasma. The fact that this was the only detectable radar event, if validated by future experiments, may suggest a method for launching an electron beam from a rocket payload with minimal vehicle charging degradation.