The computer simulated design of an improved plasma analyser towards an electron spectrometer for Solar Orbiter

The requirements for the proposed Electron Analyser System (EAS) for the ESA Solar Orbiter spacecraft pose significant challenges that cannot be addressed with existing electrostatic analyser technology. The thesis covers three core issues that are required to be addressed for this instrument. The first is the design of an electrostatic analyser head to meet the stringent requirements of the Solar Orbiter mission that could not be met with an existing geometry. A systematic series of computer simulations were undertaken, starting with an existing flight-proven geometry (Cluster II PEACE-LEEA), and covering the entire parameter space of a number of possible solutions. The final proposed geometry provides the required 10% energy resolution whilst minimizing the reduction in instrument sensitivity. In addition to this, a deflection system now provides the proposed instrument with a at analyser-constant, energy resolution and geometric factor response over the required +_45 field of view. The second issue addressed is the generalized desire for an electrostatic variable sensitivity system in Top-Hat electrostatic Analysers. Three potential solutions were studied in detail. A method was identified which permitted an order of magnitude reduction in sensitivity, whilst improving all other instrument parameters. The final study was the first to examine the effectiveness of existing secondary electron rejection mechanisms. This is particularly important for EAS, since secondary electrons have an energy distribution that overlaps significantly with the low energy Solar Wind that the instrument will be required to measure. Several improvements to rejection mechanisms have been suggested that potentially increases secondary electron rejection by a factor of four