Thermomechanical Analysis and Development of a Novel Monochromator First Crystal Using an Interference Fit: A complete redesign of first crystal assemblies from first principles

Stimson, Joshua (2019) Thermomechanical Analysis and Development of a Novel Monochromator First Crystal Using an Interference Fit: A complete redesign of first crystal assemblies from first principles. Doctoral thesis, Birmingham City University.

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Synchrotrons are particle accelerators that generate high intensity X-ray light, which is used in various disciplines including medicine (for protein sequencing), engineering (for strain analysis) and archaeology (for examination of fragile artefacts). These processes require monochromatic X-ray radiation, leading to the need for synchrotron monochromator devices. These devices are subject to demands of greater beam power and smaller footprints, such that higher resolutions can be achieved and more beamlines can be installed, as higher beam powers boost the signal to noise ratio of the experiments. This has exposed limitations in current, conventional first crystals assembly, as the heat dissipation required is very high; the first crystal receives the full beam power, and only 5-10 % is diffracted to the second crystal with the rest absorbed as heat. Through a focus on five key areas of weakness in first crystal design philosophy, a novel monochromator assembly has been constructed. The novel assembly is unconstrained at room temperature and through the use of mechanical properties is held in a firm grip at cryogenic temperatures. The deformations caused by clamping and cooling in the novel design and in a conventional design were compared experimentally; the novel design was found to exhibit surface deformations an order of magnitude lower when clamped and cooled than those observed in the conventional design due to cooling alone. The novel design had the temperature of both the crystal and heat exchanger monitored and was found to be in excellent thermal contact at cryogenic temperatures.

Item Type: Thesis (Doctoral)
Additional Information: Many thanks to the Diamond Light Source for funding this project, without which I could not have completed this work. Heartfelt thanks to Michael Ward and Peter Docker, for helping me every step of the way from base principles to experimental testing, and for always having time for a (decaf) tea or coffee and a chat, and to Richard Cornish for always showing interest. Special thanks to John Sutter, Sofia Diáz-Moreno and Jim Kay, for showing interest in my research and helping review papers, provide vital data and spend time conversing despite very busy schedules. Also to Nitika Chadha, whose practical problems helped shift my focus and clear my mind when I was stuck. And eternal gratitude to my father, Chris Stimson, for inspiring my scientific mind and instilling a work ethic from childhood; my mother, Sue Stimson, for always believing in me and praying for me; my brother, Connor Stimson, who always helps keep me grounded (brutally, at times); and especially my wife, Becky Stimson, who has inspired (and forced) me to work and has stood by me through the stressful times and kept me sane.
20 February 2019Completed
Uncontrolled Keywords: Monochromator, Interference Fit, Heat Management
Subjects: CAH10 - engineering and technology > CAH10-01 - engineering > CAH10-01-02 - mechanical engineering
Divisions: Doctoral Research College > Doctoral Theses Collection
Depositing User: Kip Darling
Date Deposited: 19 Mar 2019 16:21
Last Modified: 12 Jan 2022 13:05

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