Advances in soft x-ray performance of microchannel plate detectors.

This thesis discusses the design and improvement of microchannel plate (MCP) chevron detectors for imaging soft X-ray astronomy. Particular attention is focused on the MCP quantum detection efficiency and output pulse height distribution. Graded density electrodes are shown to be a suitable two dimensional image encoding system for MCP's. Details are given of a specially constructed vacuum system for testing chevron MCP detectors. Significant reductions in output pulse height distribution FWHM are demonstrated by applying an accelerating potential between the two MCP's of a chevron. Preliminary work on the development of a curved surface MCP detector, for use with grazing incidence optics, is reported and recommendations given for future development. The rational behind using CsI reflection photocathodes to improve the MCP's quantum detection efficiency is examined. Existing CsI photocathode techniques are reviewed and extended to allow the deposition of 14,000 A thick layers.;A detailed set of efficiency measurements is presented. Increased high angle efficiencies are obtained by using a repeller grid with a CsI coated MCP. The results of attempting to produce an MCP with an input electrode that does not penetrate into the channels are also described. The overall usefulness of a repeller grid is discussed. Significant intrinsic energy resolution is achieved, for the first time, from a CsI coated MCP chevron. The resolution is sufficient to allow two colour photometry, separating energies above and below 1 keV. One attempt to improve the energy resolution is documented together with suggestions for further ways in which this might be achieved.h.