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|Title: ||The Development of a Wide Field UV Imager for Planetary Space Missions|
|Authors: ||Molyneux, Philippa Mary|
|Supervisors: ||Bannister, Nigel|
|Award Date: ||22-Jun-2012|
|Presented at: ||University of Leicester|
|Abstract: ||This thesis describes the development of the Jupiter system Ultraviolet Dynamics
Experiment (JUDE): a far ultraviolet (FUV) imager designed for the JUICE mission to Jupiter and Ganymede. To date the only in situ UV instruments to study Jupiter’s aurora have been spectrographs or spectral imagers, which are unable to provide instantaneous large-scale images. JUDE will obtain such images, thus providing information on highly variable, small scale features in Jupiter’s auroral regions, allowing models of the global magnetospheric dynamics that produce the emissions to be refined. The imager will also observe Ganymede’s FUV auroral emissions, which have not yet been comprehensively studied.
Two preliminary designs for the JUDE optics have been proposed: one based on reflective optics (developed at the University of Liège, Belgium) and one based on novel microchannel plate (MCP) optics. An overview of both optical designs is given in Chapter 2, along with a description of the detector and readout electronics that will complete the instrument. Chapters 3 and 4 then detail a feasibility study for the MCP optic version, based on sequential ray tracing modelling of the system and laboratory tests of similar optics. The results of the modelling suggest that diffraction effects would severely limit the achievable resolution of the MCP optic. Similarly, images obtained by real MCP optics of two different specifications indicate that the theoretical resolution of each optic is not achievable, although in this case problems in the optic manufacturing process are more to blame than diffraction. Hence, the MCP optic version of JUDE would be unable to produce high quality images of small auroral features at Jupiter, and is rejected in favour of the reflective optic design.
JUDE is a broadband instrument, but the isolation of two FUV emission lines at 130.4 nm and 135.6 nm is desirable, as the relative intensity of these lines at Ganymede provides information on the moon’s atmosphere. Chapter 5 outlines an investigation into the possibility of isolating these emissions using a combination of reflective multilayer coatings and commercially available transmission filters. The results are promising: in the absence of significant background emissions in the FUV region, the ratio of the two lines was calculated using simultaneous equations to within ~1% of the known value.
Although MCP optics were found to be unsuitable for JUDE, they are ideal for other applications with less stringent resolution requirements. A summary of potential imagers based on variations of the JUDE MCP optic design is given in Chapter 6.|
|Rights: ||Copyright © the author, 2012|
|Appears in Collections:||Leicester Theses|
Theses, Dept. of Physics and Astronomy
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