The nEXO experiment is a proposed 5-ton enriched liquid xenon time projection chamber (TPC) that will search for the neutrino-less double beta decay of 136Xenon. Work is being done regarding the liquid xenon fluid system focused on fluid turnover and internal heat source management. The detector utilizes charge tile readout chips located within the cryogenic media to amplify and digitize a total of 50,000 individual light and charge channels inside the nEXO TPC. Simulations indicate that with the current detector operating pressure and temperature the excess heat from the Application-Specific Integrated Circuit (ASIC) chips will cause localized power densities sufficient to create sustained boiling. This boiling presents an increased risk for electric discharges inside the detector that could damage components.
This research attempts to advance the understanding of the thermal properties of liquid xenon at atmospheric and elevated pressure in an effort to prevent boiling inside the detector. A combination of computational fluid dynamics simulations and experimental data using flat surface resistors in a cryogenic liquid test cell provided a precision measurement of the onset of nucleate boiling in liquid xenon. This information was used to develop prototype designs for high radiopurity silicon and silicon carbide heat sinks which can then be attached to functioning ASIC chips and tested in the cryogenic test cell.
|Commitee:||Iannelli, Joseph, Saad, Messiha, Lewis, Robert R.|
|School:||Washington State University|
|School Location:||United States -- Washington|
|Source:||DAI-B 82/9(E), Dissertation Abstracts International|
|Subjects:||Mechanical engineering, Thermodynamics, Fluid mechanics|
|Keywords:||Boiling analysis, Convection, Cryogenics, Liquid Xenon, Thermal fluid simulations, NEXO detector|
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