A wide field ultrasoft X-ray camera for astronomy
In a collaboration between the University of Leicester X-ray Astronomy Group and the Center for Space Research at the Massachusetts Institute of Technology an imaging X-ray telescope has been developed to carry out a partial sky survey of the extreme-ultraviolet (EUV) region of the spectrum in the waveband 50 to 250A. The instrument is designed to be flown on NASA Astrobee or Black Brant sounding rockets. The history of EUV astronomy and the types of object likely to be of interest in the EUV are reviewed. The development of the WFSXC payload is described with particular emphasis on the development of the focal plane instrument, a microchannel plate detector with resistive anode image readout. The gain performance of the detector is summarised and the use of MgF2 and CsI photocathodes to enhance its quantum efficiency is described, CsI giving efficiencies 10-20 times higher than uncoated MCPs. Also, the use of a resistive anode to provide a low distortion high resolution image readout is demonstrated. Thin film filters are used to define the instrument bandpasses and reject geocoronal background and their design and testing are described. The linear absorption coefficients of beryllium and parylene N, derived from the measured filter transmissions, are compared with theoretical predictions of the absorption in the 50-300A waveband showing good agreement up to 300A for beryllium and 100A for parylene. The WFSXC payload was flown twice experiencing technical problems on both occasions. The anaylsis and interpretation of the data from these flights is presented in the latter chapters of this thesis and the likely causes of the problems determined.