Meredith, Nigel Peter; (1990) Narrow band imaging and Doppler imaging of natural and artificial gas and plasma clouds in the interplanetary medium and in the Earth's magnetosphere. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The properties and dynamics of gas and plasma clouds within the solar wind and in the magnetosphere may be determined by studying the motion and evolution of these clouds in the appropriate region. These clouds may occur naturally, as in the case of cometary atmospheres, or they may be generated by injection of suitable tracer materials from rockets or satellites. Optical observations of the resulting distributions of ions and neutrals, under all of the above conditions, have been performed using an Imaging Photon Detector, in conjunction with a set of narrow-band interference filters. Line of sight velocity maps of the ions and neutrals have been obtained using a Doppler Imaging System, consisting fundamentally of a Fabry-Perot etalon coupled to an Imaging Photon Detector. The spatial distributions of the neutral cometary species CN and C₂ have been monitored over a wide range of heliocentric distances to yield important information on possible production and destruction mechanisms. The study of cometary plasmas is characterized by the fact that cometary ions, in particular CO⁺ and H₂O⁺, can be used as tracers for the dynamical processes taking place. The large-scale and nearnucleus images of the ion coma and tail of the comets Giacobini-Zinner and Hailey are compared and contrasted with each other and with the spacecraft results. Imaging and Doppler Imaging Systems have been used to observe several artificially injected plasma clouds in both the magnetosphere and the near space environment. When released in the magnetosphere, the migrating ions trace out the distant field and provide direct evidence of the topology of the field. In the near space environment, the interaction of the plasma with the solar wind resembles in many respects the processes occurring in the plasma tails of comets.

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