Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"Cryogenic Cooling"”.
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Analysis of Cryogenic Cooling of Toroidal Field Magnets for Nuclear Fusion Reactors
… We investigate the heat transfer inside the cooling channels and uid dynamics inside the cooling channels. System-level issues are also investigated, including impact of an insulated versus non-insulated design on cooling performance and cryodistribution architectures to provide coolant …
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Improved thermal design of the cryogenic cooling system for a superconducting synchronous generator.
Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering.
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Investigation of cryogenic cooling for a high-field toroidal field magnet used in the SPARC fusion reactor design
… through the HTS-based magnets, a new set of cryogenic fluids are being considered for forced flow cooling. This thesis analyzes the thermophysical properties of helium, hydrogen, and neon, and constructs a numerical model to investigate the forced flow cooling for REBCO HTS tapes under the …
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Infrared photoconductive PbTe film processing and oxygen sensitization
… use narrow gap semiconductor materials requiring cryogenic cooling to provide measurable signals above thermally generated noise. Our study investigates one class of photodetectors, namely photoconductive semiconductor films. When embedded within resonant cavities, these films are additionally …
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High field, high efficiency terahertz pulse generation by optical rectification
… pump beam imaging, pump pulse optimization, cryogenic cooling, and THz antirefiection coating. Finally, experimental results will be presented showing a THz generation efficiency of 3.7%, which is 10x higher than current state-of-the-art. The generated few-cycle THz pulses can be used for …
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Ultra-sensitive Mid-infrared Detection Using Phononic Crystal Resonator-based Oscillator
… and fast response time but typically require cryogenic cooling, and (2) thermal-based sensors, which can operate at room temperature but suffer from low sensitivity and slow response times. In this thesis, I demonstrate room-temperature MIR detectors based on surface acoustic wave (SAW) …
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A cryogenic multiaxis range-resolved laser interferometer
… must be both large and cold, which requires cryogenic cooling of the mirrors, instrumentation, and detectors. The precision to which the moving cryogenic components of the instrument must be measured and controlled demands a robust low power position metrology system, and a cryogenic …
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Vapor-liquid-solid (VLS) growth of lead chalcogenide thin films for infrared sensing applications
… but expensive and cumbersome due to the need for cryogenic cooling, while thermal detectors are inexpensive but not very sensitive. The goal of this project is to develop materials for uncooled IR sensors with improved performance. Lead selenide (PbSe) detectors are direct narrow band gap …
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Multi-element superconducting nanowire single photon detectors
… (SNSPDs) and the unavoidable overhead of cryogenic cooling make SNSPDs particularly likely to be used in applications that require detectors with the highest performance available. These applications are also the most likely to benefit from and fully utilize the large amount of information …
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Towards room-temperature Terahertz Quantum Cascade Lasers : directions and design
… Their main limitation is that they require cryogenic cooling, which dominates their ownership cost. Therefore, achieving room-temperature operation is essential for the widespread adoption of THz QCLs. This thesis analyzes the limitations of THz QCL maximum lasing temperature (Tmax) and …
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Superconducting Asynchronous Logic for Ultra-low Power High Performance Computing
… consumption, while still accounting for the cryogenic cooling overhead of the superconducting electronics. Beyond the dramatic power performance improvement with this logic technology and architecture, it also allows for designers to rapidly prototype hardware computing optimizations without …
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The Wide-Field Infrared Transient Explorer (WINTER): a new near-infrared time-domain survey
… near-infrared astronomical imaging without cryogenic cooling. The custom camera combines six InGaAs detectors with a novel tiled fly’s-eye optical design to cover a >1 degree-squared field of view with a 90\% fill factor. WINTER observes in the Y-, J-, and shortened-H-band filters (0.9-1.7 …
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High fidelity quantum gates with ions in cryogenic microfabricated ion traps
… source and suppression of this decoherence at cryogenic temperatures, and demonstrates fundamental logic gates in a surface electrode ion trap. Construction of the apparatus requires the development of a number of experimental techniques. Design, numerical simulation and implementation of a …
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Modeling of a compact terahertz source based on the two-stream instability.
… to operate. Optical sources necessitate cryogenic cooling and are presently capable of producing milliwatt levels of power at THz frequencies. We propose a millimeter and sub-millimeter wave source based on a well-known phenomenon called the two-stream instability. The two-beam source …
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The Acoustic Expander: A New Expansion Machine for Use in Cryogenic Refrigeration
… expansion machine with potential applications to cryogenic refrigeration and liquefaction. Cryogenic expansion machines produce mechanical energy from the expansion of a working fluid from high-pressure to low-pressure thereby cooling the low-pressure fluid for use in refrigeration. The novelty of …
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Modelling and Control of Magnetic Fusion Plants Based on ARM CPU and STM32 MCU Platforms
… plants like electric distributors, water, and cryogenic cooling pumps, running on off-the-shelf hardware (PLC/PAC/PXI). The presented work result falls under the PCS subsystem categorisation and follows a path starting with the study of the model for the vertical stabilisation of the plasma …
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Bayesian atmospheric retrieval for exoplanets : uniqueness of exoplanet spectra, characterizations of super-earths, and evaluations of dedicated space telescope designs
… payload module. I demonstrate that costly cryogenic cooling to observe the mid-infrared spectrum beyond ~ 11 [mu]m is not required while visible light observations down to - 400 nm are essential for the mission success. The observational study of exoplanet atmospheres is in its infancy and …
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Numerical Study Of A High-speed Miniature Centrifugal Compressor
… is a key component of a reverse Brayton cycle cryogenic cooling system. The system is commonly used to generate a low cryogenic temperature environment for electronics to increase their efficiency, or generate, store and transport cryogenic liquids, such as liquid hydrogen and oxygen, where …
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Effects of milling methods, cooling strategies and end-mill coatings on machinability in high speed end-milling of Inconel- 718 using carbide end-mills
… affinity with many cutting tools. Appropriate cooling strategies, milling methods, tool coatings and cutting speeds play important roles in addressing these problems. This research presents the results of the effects of end-milling methods (Up and down-milling), cooling strategies (Conventional …
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Analysis and Design of High-Speed Induction Machines for Submerged Cryogenic Pumps
L'abstract é presente nell'allegato / the abstract is in the attachment