Thermal Design Study of the Electrical Cabling System of Cryogenic Payloads in the Einstein Telescope

This thesis presents a thermal design study of the electrical wiring system in the cryogenic payloads of the Einstein Telescope's low-frequency interferometer (ET-LF). In cryogenic gravitational wave detectors, electrical wires act as significant sources of parasitic heat loads due to both Joule heating and thermal conduction, directly affecting detector performance. A key contribution of this work is the selection and integration of specific payload instruments and their corresponding electrical requirements based on a comparative analysis of the Advanced Virgo Plus (AdV+) and KAGRA detectors. The instruments chosen serve as the foundation for a proposed instrumentation concept tailored to the needs of ET. A thermal model of electrical wires was developed, including conduction and Joule heating, and used to evaluate six thermal scenarios under different cooling strategies and wiring schemes. The final result is a design proposal for a low-heat-load electrical wiring system for the ET-LF payload, supported by an optimization methodology that considers geometry, material selection, and thermal anchoring. This thesis was submitted in partial fulfillment of a B.Sc. degree in Chemical and Process Engineering at the Karlsruhe Institute of Technology (KIT).