A novel approach to ultraviolet auroral imaging using microchannel plate technology
This thesis is an account of the work undertaken in proving that the imaging of the Earth's aurora in far ultraviolet wavelengths using microchannel plate (MCP) optics from a platform in low-Earth-orbit (LEO) is feasible. Using POLAR UVI imager data and particle flux data from the FAST spacecraft, the relationship between electron and proton energy flux and the UV auroral intensity during the substorm of August 26, 1998 is investigated. The findings show that protons are a significant contributor to the electron aurora. The analysis of this data coupled with a review of previous imagers demonstrates the ongoing need for auroral imaging allowing the science case for a LEO imager to be presented alongside baseline goals for the required performance of the MCP optics, to be established. Illumination of an early, prototype optic with a quasi-parallel beam of ultraviolet light determines the suitability of MCP optic technology for auroral imaging from LEO. Successful focussing of UV light using the optic is demonstrated and verified by Monte Carlo simulation. The results of this work demonstrate that MCPs are a suitable technology with which to produce a LEO auroral imager. A conclusion supported by the preliminary analysis of additional MCPs specifically deigned for such an imager. Tests of a slumped microchannel plate detector of small curvature radius, deigned for use with a slumped MCP optic, are described. The use of a slumped detector provides the required curved focal surface without the expense of the more common grinding technique, and the results prove that the technique is viable. A preliminary design study of an MCP-based imager for use in an 800 km LEO is conducted, and its performance compared to baseline goals derived in part from the analysis of POLAR/FAST data with encouraging results.