UBC Theses and Dissertations
Thermal conductivity in ISOL target materials : development of a numerical approach and an experimental apparatus Au, Mia
The method of Isotope Separation On-Line (ISOL) is one of the most successful ways to produce rare nuclei. Hitting a target material with accelerated particles generates heat and reaction products which then diffuse and effuse through the target material before they are released for ionization and extraction for experiments in nuclear physics, astrophysics, materials science, pharmaceuticals, and many more. The target material temperature dominates the release process and is limiting the primary beam intensity. Heat is dissipated from the beam spot through the target material, making the effective thermal conductivity of the target material critical for the ISOL process. Specifically-engineered microstructures have the potential to achieve better release properties. To address the thermal challenges in target materials, a deeper understanding of the thermal conductivity of these engineered materials is required. In this work, a numerical method is developed for evaluating the effective thermal conductivity of representative microstructures. A combined parallel and series model agrees with numerical data of four representative microstructures when thermal radiation through pores is considered by fitting a morphological parameter and a parameter describing the portion of series connections. Separately, a steady-state experimental-numerical method is used to determine the effective thermal conductivity of porous β-SiC slip-cast material and β-SiC pressed pellet material as a function of temperature up to 1200˚C and 1050˚C respectively. In addition, a new experimental apparatus for effective thermal conductivity is presented from conceptual design to operation. This thesis works towards understanding thermal transport through target materials. The new numerical method for material analysis, effective thermal conductivity measurements on SiC, and the establishment of the CHI system at TRIUMF for thermal conductivity measurements on target materials help build towards systematic studies of engineered materials in ISOL and beyond.
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