Electron optical simulations of variable sensitivity systems for top-hat electrostatic space plasma analysers

Glyn Collinson and Dhiren Kataria (Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey, UK)

Electrostatic analysers are required to operate under a broad range of particle flux. The current approach to providing good sensitivity under all conditions is to build and fly multiple sensor heads (such as the Cluster PEACE instrument). This doubles the required mass and power requirements for the instrument. A far more elegant solution would a single sensor with variable sensitivity. We present three possible electrostatic methods for varying the sensitivity (geometric factor) of a space plasma analyser, and a discussion of the advantages and disadvantages of each method.