The thermodynamics inside the helium liquefier in the FREIA laboratory still contains many unknowns. The purpose of this project is to develop a theoretical model and implement it in MATLAB, with the help of the CoolProp library. This theoretical model of the FREIA liquefaction cycle aims at finding the unknown parameters not specified in the manual of the manufacturer, starting from the principle of enthalpy conservation. Inspiration was taken from the classical liquefaction cycles of Linde-Hampson, Claude and Collins. We developed a linear mathematical model for cycle components such as turboexpanders and heat exchangers, and a non-linear model for the liquefaction in the phase separator. Liquefaction yields of 10% and 6% were obtained in our model simulations, with and without liquid nitrogen pre-cooling respectively - similar to those in the FREIA liqueuefier within one percentage point. The sensors placed in FREIA showed similar pressure and temperature values, even though not every point could be verified due to the lack of sensors. We observed an increase of more than 50% in yield after adjustments of the heat exchanger design in the model, especially the first one. This constitutes a guideline for possible future improvements of the liquefier. / Termodynamiken bakom heliumförvätskaren i FREIA-laboratoriet innehåller fortfarande många okända aspekter. Detta kandidatarbete syftar till att utveckla en teoretisk modell och implementera den i MATLAB med hjälp av biblioteket CoolProp. Denna modell av FREIA:s förvätskningscykel syftar till att hitta de okända parametrar som inte specificerats av tillverkaren, och baserar sig på principen om entalpins bevarande. Inspiration togs från de klassiska förvätskningscyklerna Linde-Hampson, Claude och Collins. Vi utvecklade en linjär matematisk modell för cykelkomponenter såsom expansionsturbiner och värmeväxlare, och en icke-linjär modell för själva förvätskningen i fasseparatorn. En förvätskningsverkningsgrad på 10% och 6% uppnåddes i våra modellsimuleringar, med respektive utan förkylning med flytande kväve - liknande verkningsgraderna i FREIA- förvätskaren inom en procentenhet. Sensorerna placerade i FREIA visade på liknande tryck och temperaturer, även om bristen på sensorer gjorde att vi inte kunde bekräfta varje punkt. Vi observerade en ökning på mer än 50% i verkningsgrad efter att ha justerat värmeväxlardesignen något, speciellt för den första. Detta kan utgöra riktlinjer för var man framöver kan förbättra den faktiska förvätskaren. / <p>Subject reader/Ämnesgranskare: Roger Ruber</p>

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Há alguns anos, diversos estudos da influência dos parâmetros do tratamento térmico vêm sendo desenvolvidos, para a obtenção de propriedades que permitam atingir os requisitos de trabalho e que gerem ferramentas de vida útil estendida. Nesse contexto, tem sido demonstrado que o tratamento criogênico não só provoca a transformação da austenita residual, trazendo melhorias no dimensional da ferramenta, mas também pode promover a precipitação de carbonetos finos, com ganho em tenacidade e propriedades de desgaste.Neste estudo são relatados os resultados obtidos de ensaios de dureza, desgaste, impacto Charpy e microscopia TEM, efetuado em amostras de aço H13.Os tratamentos térmicos foram realizados em forno a vácuo com resfriamento por nitrogênio sob 5 bar de pressão, sendo utilizados os seguintes parâmetros: austenitização1040ºC, têmpera, e revenimento a 540ºC. As amostras foram comparadas com a condição de base que passou por tratamento térmico convencional, as outras condições foram submetidas a um revenido alternado com o banho criogênico. Nas rotas criogênicas o tempo de encharque em nitrogênio líquido foi de 1, 24 e 48 horas. Uma análise desses resultados permitiu constatar que o tratamento criogênico melhora a resistência ao desgaste, e influencia levemente a dureza. / A few years ago, several studies of the influence of parameters heat treatment have been developed to obtain properties that could meet the job requirements and managing tools for extended life. In this context, it has been demonstrated that the cryogenic treatment not only causes the transformation of austenite residual, bringing improvements in dimensional tool, but also can promote the precipitation of fine carbides, and an increase in toughness and wear properties. In this study there are the results of the test of hardness, two body abrasion wear, Charpy impact followed by microscopy TEM analyses were performed in samples from H13 steel. The heat treatments were performed in a vacuum furnace with cooling by nitrogen under pressure of 5 bar, and used the following parameters: austenitizing 1040°C, quenching, and tempering at 540°C. The aim was compared the H13 performance under of conventional heat treatment and cryogenic bath after quenching and before tempering. Soaking times in the cryogenic temperature were: 1, 24, and 48 hours. Analyses this results has shown the heat treatment increased the wear resistance, and slightly affects the hardness.

Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-26T12:16:03Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Estudo das propriedades mecânicas e tribológicas do aço modificado ABNT M2 através da otimização de tratamentos térmicos e criogênicos.pdf: 121658018 bytes, checksum: bfd16276bda8accde8024249e4dd9ede (MD5) / Approved for entry into archive by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-26T12:16:55Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Estudo das propriedades mecânicas e tribológicas do aço modificado ABNT M2 através da otimização de tratamentos térmicos e criogênicos.pdf: 121658018 bytes, checksum: bfd16276bda8accde8024249e4dd9ede (MD5) / Made available in DSpace on 2017-01-26T12:16:55Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Estudo das propriedades mecânicas e tribológicas do aço modificado ABNT M2 através da otimização de tratamentos térmicos e criogênicos.pdf: 121658018 bytes, checksum: bfd16276bda8accde8024249e4dd9ede (MD5) Previous issue date: 2016-06-20 / O aço rápido ABNT M2 e usado frequentemente na confecção de ferramentas de usinagem. Esse aço, quando submetido a tratamentos térmicos de temperatura e revenido, tratamentos responsáveis por transformar uma microestrutura esferoidizada em uma microestrutura martensítica com grãos finos e reforçada por carbetos, se torna um material com alta dureza e com boa resistência ao desgaste, duas características importantes para ferramentas. Em busca de processos que produzam melhores propriedades, em 1930, pesquisadores introduziram nas rotas convencionais o tratamentos denominado de subzero (< 80º C), com o objetivo de alcançar a temperatura de transformação completa da austenita em martensita. Com o avanço das pesquisas, surgiu um novo tratamento térmico denominado de Tratamento Criogênico profundo, que consiste em resfriar a ferramenta em temperaturas próximas a do nitrogênio liquido (-196º C) e mantê-la nessa temperatura por um período de tempo, geralmente 24horas. Inúmeros resultados mostram que a introdução da criogenia nos ciclos de tratamento convencionais resulta em ganho de resistência ao desgaste, propriedade que e fundamental nas ferramentas. Atribui-se esse ganho a dois fenômenos: transformação completa da austenita em martensita e a precipitação de finos carbetos distribuídos homogeneamente na estrutura martensitica. Nesse contexto, o objetivo desse trabalho foi analisar a influencia do Tratamento Criogênico em conjunto com os tratamentos de temperatura e revenido sobre propriedades mecânicas e tribológicas do aço rápido ABNT M2 modificado, variando-se a temperatura de austerização (1185º C, 1200º C e 1215º C), a temperatura de revenimento (520º C. 535º C e 550º C) e o tempo em temperatura criogênica (20 e 28 horas). A metodologia empregada consiste em um planejamento e otimização experimental, utilizando o método de Taguchi L9. As propriedades mecanicas das amostras foram analisadas em termos de microdureza Vickers, dureza Rockwell C, ensaio Charpy e ensaio de desgaste abrasivo. Os resultados encontrados nos ensaios mecânicos foram submetidos a analise estatística ANOVA. As microestruturas das amostras foram investigadas em termos de microscopia óptica, microscopia eletrônica de varredura (MEV) e difração de raios X. Os resultados permitiram traçar superfícies de respostas, possibilitando a determinação dos parâmetros ótimos de tratamento. A melhor temperatura de Austerização e a de 1200º C, o Tratamento Criogênico melhorou todas as propriedades mecânicas, principalmente com tempos de 20 horas, e a Temperatura de Revenimento e fundamental sobre os resultados finais, sendo 550º C a temperatura que gerou os melhores resultados. / The speed steel ABNT M2 is often used in the manufacture of machining tools. This steel, when subjected to heat treatments of quenching and tempering, treatments responsible for transforming a spheroidized microstructure in a martensitic microstructure with fine grains and reinforced by carbides becomes a material with high hardness and good wear resistance, two important feature for tools. In search processes that produce the best properties in 1930, researchers introduced in conventional routes treatments called subzero (<80º C), in order to achieve complete transformation temperature of austenite into martensite. With the advancement of research, a new heat treatment called Deep Cryogenic Treatment, consisting in cooling the tool at temperatures near the liquid nitrogen (-196 ° C) and keep it at this temperature for a period of time, usually 24 hours. Numerous results show that the introduction of cryogenics treatment in conventional cycles results in wear resistance gain property that is essentials in tools. It attributed this gain to two phenomena: complete transformation of austenite into martensite and the precipitation of fine carbides distributed homogeneously in the martensitic structure. In this context, the aim of this study was to analyze the influence of Treatment Cryogenic together with the quenching treatment and tempering on the mechanical and tribological properties of high speed steel ABNT M2 modified, varying the austenitization temperature (1185º C, 1200º C and 1215º C) tempering temperature (520 ° C 535 ° C and 550 ° C) and the time at cryogenic temperature (20 and 28 hours). The methodology consists of a planning and experimental optimization, using the method Taguchi L9. The mechanical properties of the samples were analyzed in terms of Vickers hardness, Rockwell hardness C, Charpy test and wear resistance test. The results in mechanical tests were subjected to statistical analysis ANOVA. The microstructures of the samples were investigated in terms of optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction. The results trace responses surfaces, enabling the determination of the optimal treatment parameters. The best austenitizing temperature is 1200 º C, the Treatment Cryogenic improved all the mechanical properties, especially with times of 20 hours, and the tempering temperature is critical for the final results, with 550º C temperature led to the best results.

Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-26T10:43:23Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Influência do tratamento criogênico nas propriedades mecânicas e tribológicas do aço ABNT M2.pdf: 19371042 bytes, checksum: 86cfc4da7ebbbbb0684e4a589f03b84f (MD5) / Approved for entry into archive by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-26T10:44:23Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Influência do tratamento criogênico nas propriedades mecânicas e tribológicas do aço ABNT M2.pdf: 19371042 bytes, checksum: 86cfc4da7ebbbbb0684e4a589f03b84f (MD5) / Made available in DSpace on 2017-01-26T10:44:23Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Influência do tratamento criogênico nas propriedades mecânicas e tribológicas do aço ABNT M2.pdf: 19371042 bytes, checksum: 86cfc4da7ebbbbb0684e4a589f03b84f (MD5) Previous issue date: 2015-06-18 / O aumento da resistência mecânica dos aços sempre foi objeto de investigação desde os tempos mais remotos. Nos últimos dois séculos, com o aumento da industrialização, a demanda por materiais cada vez mais resistentes se tornou ainda maior. Dentre os materiais metálicos, os aços ferramentas são os mais pesquisados na busca de aumento de dureza, resistência ao desgaste e tenacidade, requisitos essenciais à sua utilização. Nos últimos anos tem sido demonstrado que o tratamento criogênico profundo aplicado aos aços ferramentas provoca, além da transformação da austenita residual em martensita, a precipitação de finos carbetos na matriz metálica, aumentando principalmente a resistência ao desgaste. Esta pesquisa tem como objetivo estudar a influência do tratamento criogênico profundo nas propriedades mecânicas e tribológicas do aço ABNT M2. Foram realizados ensaios de dureza HRC, microdureza HV e HK, impacto Charpy, desgaste abrasivo, microscopia óptica e microscopia eletrônica de varredura em amostras de aço ABNT M2 submetidas ao tratamento térmico convencional (têmpera e revenido) e ao tratamento térmico convencional com tratamento criogênico. O tratamento criogênico foi realizado por nebulização direta com taxa de resfriamento e aquecimento de 0,3° C/min e permanência de 24 horas na temperatura de -190° C. As temperaturas de austenitização empregadas foram de 1170° C, 1200° C e 1230° C. Foram analisadas amostras com aplicação de revenido antes, após e antes/após o tratamento criogênico. Concluiu-se que o tratamento criogênico profundo aplicado antes do revenido em amostras austenitizadas à temperatura de 1200° C aumenta a dureza, a resistência ao desgaste abrasivo e a tenacidade do material tratado. / The increased resistance of steels has always been under investigation since the earliest times. In the last two centuries, with the rise of industrialization, the demand for increasingly resistant materials became even greater. Among the metallic materials, tool steels are the most investigated in the search for higher hardness and wear resistance, essential to use requirements. In recent years it has been demonstrated that deep cryogenic treatment applied to tool steels causes not only the transformation of residual austenite into martensite, precipitation of fine carbides in the metal matrix, mainly by increasing wear resistance. This research aimed to study the influence of deep cryogenic treatment on mechanical properties and tribological steel AISI M2. Hardness tests were performed HRC, HV and HK microhardness, Charpy impact, abrasive wear, optical and scanning electron microscopy in ABNT M2 steel samples subjected to conventional heat treatment (quenching and tempering) and conventional heat treatment with cryogenic treatment. The cryogenic treatment was performed by direct nebulization with heating and cooling rate of 0.3° C/min and 24 hours residence in -190° C. The austenitization temperatures used were 1170° C, 1200° C and 1230° C. Samples were analyzed with tempering application before, after and before after the cryogenic treatment. It was concluded that deep cryogenic treatment applied before tempering samples austenitized at a temperature of 1200° C increases the hardness, abrasive wear resistance and toughness of the treated material.

abstract: Seeking an upper limit of the Neutron Electric Dipole Moment (nEDM) is a test of charge-parity (CP) violation beyond the Standard Model. The present experimentally tested nEDM upper limit is 3x10^(26) e cm. An experiment to be performed at the Oak Ridge National Lab Spallation Neutron Source (SNS) facility seeks to reach the 3x10^(28) e cm limit. The experiment is designed to probe for a dependence of the neutron's Larmor precession frequency on an applied electric eld. The experiment will use polarized helium-3 (3He) as a comagnetometer, polarization analyzer, and detector. Systematic influences on the nEDM measurement investigated in this thesis include (a) room temperature measurements on polarized 3He in a measurement cell made from the same materials as the nEDM experiment, (b) research and development of the Superconducting QUantum Interference Devices (SQUID) which will be used in the nEDM experiment, (c) design contributions for an experiment with nearly all the same conditions as will be present in the nEDM experiment, and (d) scintillation studies in superfluid helium II generated from alpha particles which are fundamentally similar to the nEDM scintillation process. The result of this work are steps toward achievement of a new upper limit for the nEDM experiment at the SNS facility. / Dissertation/Thesis / Doctoral Dissertation Physics 2019

Le but de cette thèse est d'atteindre l'état de mouvement fondamental sur des disques optomécaniques en arseniure de gallium. La mécanique quantique prévoit en effet que la quantité d'énergie d'un système physique (mécanique ou autre) ne peut jamais être réduite totalement à zéro. Il existe cependant un état de plus basse énergie, que l'on appelle l'état fondamental. L'effet physique utilisé pendant cette thèse pour extraire de l'énergie du système (et ainsi atteindre l'état fondamental) est le couplage opto-mécanique. Les micro-disques supportent des résonances optiques à symétrie axiale appelées modes de galerie ainsi que des résonances mécaniques appelées modes de respiration. Le couplage entre ces deux modes peut être intuitivement compris comme suit: lorsque le disque "respire" mécaniquement, la circonférence du disque ressentie par le mode optique change, ce qui induit un décalage de sa longueur d'onde de résonance. A l'inverse, le mode optique exerce une pression de radiation sur les parois du disque, qui peut amplifier ou atténuer le mouvement mécanique. Le refroidissement opto-mécanique est d'autant plus efficace que les résonances (optique comme mécanique) ont de faibles taux de dissipation. Une grande partie de ce travail de thèse à donc été dédiée à la réduction de ces pertes. Des efforts technologiques ont permis d'obtenir des structures lisses et régulières, pour éviter la diffusion (et donc la dissipation) de lumière par rugosités. Afin de réduire la dissipation mécanique, une structure novatrice incluant des boucliers mécaniques à été développée, et à permis de réduire la dissipation mécanique d'un facteur 100. L'état du système après refroidissement opto-mécanique dépend par ailleurs de sa température initiale. Il est donc avantageux de placer l'échantillon dans un cryostat. L'appareil utilisé au cours de cette thèse permet de refroidir l'échantillon jusqu'à une température de 2,6 K. Les expériences de photonique en environnement cryogénique imposant des contraintes en terme de stabilité, il a été nécessaire de d'opter pour une approche avec guide d'onde intégré. Le développement de guides d'ondes entièrement suspendus a permis d'apporter et de collecter la lumière depuis le disque de manière optimale. Toutes ces efforts ont permis de descendre à un taux d'occupation mécanique de 30 quanta. Cependant de nombreuses améliorations peuvent encore être implémentées, afin d'ancrer ces résonateurs fermement dans l'état fondamental, ce qui permettrait d'effectuer par exemple des expériences d'intrication quantique / The main goal of this PhD work has been to reach the quantum ground state on gallium arsenide optomechanical disks. Quantum mechanics predict that the amount of energy within a given system cannot be brought to zero. Nevertheless a state of minimal energy exists, called the ground state. The physical mechanism used to extract energy from the system (and thus reach the ground state) is the optomechanical coupling. The miniature disks support optical and mechanical resonances, respectively called whispering gallery modes and radial breathing modes. The coupling between these two modes can be intuited as follows: when the disk breathes mechanically, its perimeter increases. The optical mode evolves now in a wider cavity, and its resonance wavelength therefore changes. Conversely, the optical mode exerts radiation pressure on the disk boundaries, which can either amplify or damp the mechanical motion. Optomechanical cooling is more efficient if the dissipation rates of the optical and mechanical resonances are low. An important part of this PhD work has therefore been dedicated to the reduction of dissipation. Technological efforts have been made to fabricate smooth and regular structures, so as to limit optical scattering. A novel approach consisting of a mechanical shield has allowed to reduce mechanical damping by a factor of 100. The system state after optomechanical cooling depends on its initial temperature. It is therefore advantageous to place the system in cryogenic environment prior to starting the optomechanical cooling. The apparatus used throughout this PhD work can cool the optomechanical device down to 2.6 K. As optical experiments in cryogenic environment require a good mechanical stability, it is necessary to opt for fully integrated devices where the optomechanical resonator and the waveguide bringing the light to it are processed on the same chip. The development of fully suspended waveguides has moreover allowed to inject and collect light from the device more efficiently. All these improvements have allowed to reach a state of 30 excitation quanta in the mechanical resonator. However many ideas can still be tried to keep enhancing the devices, so as to anchor them more firmly in the ground state. This would open the way to more advanced experiments, such as entanglement of mechanical oscillators

<p>The topic of this thesis concerns the LHC, the next large particle accelerator at CERN which will start operating in 2007. Being based on superconductivity, the LHC needs to operate at very low temperatures, which makes great demands on the cryogenic system of the accelerator. To cope with the heat loads induced by the particle beam, a beam screen cooled with forced flow of supercritical helium is used.</p><p>There is an interest in upgrading the energy and luminosity of the LHC in the future and this would require a higher heat load to be extracted by the beam screen cooling system. The objective of this thesis is to quantify different ways to upgrade this system by mainly studying the effects of different pressure and temperatures levels as well as a different cooling medium, neon.</p><p>For this a numerical program which simulates one-dimensional pipe flow was constructed. The frictional forces were accounted for by the empirical concept of friction factor. For the fluid properties, software using empirically made correlations was used. To validate the numerical program, a comparison with previous experimental work was done. The agreement with experimental data was good for certain flow configurations, worse for others. From this it was concluded that further comparisons with experimental data must be made in order to tell the accuracy of the mathematical model and the correlations for fluid properties used.</p><p>When using supercritical helium, thermo-hydraulic instabilities may arise in the cooling loop. It was of special interest to see how well a numerical program could simulate and predict this phenomenon. It was found that the numerical program did not function for such unstable conditions; in fact it was much more sensitive than what reality is.</p><p>For the beam screen cooling system we conclude that to cope with the increased heat loads of future upgrades, an increase in pressure level is needed regardless if the coolant remains helium, or is changed to neon. Increasing the pressure level also makes that the problems with thermo-hydraulic instabilities can be avoided. Of the two coolants, helium gave the best heat extraction capacity. Unlike neon, it is also possible to keep the present temperature level when using helium.</p>

The topic of this thesis concerns the LHC, the next large particle accelerator at CERN which will start operating in 2007. Being based on superconductivity, the LHC needs to operate at very low temperatures, which makes great demands on the cryogenic system of the accelerator. To cope with the heat loads induced by the particle beam, a beam screen cooled with forced flow of supercritical helium is used. There is an interest in upgrading the energy and luminosity of the LHC in the future and this would require a higher heat load to be extracted by the beam screen cooling system. The objective of this thesis is to quantify different ways to upgrade this system by mainly studying the effects of different pressure and temperatures levels as well as a different cooling medium, neon. For this a numerical program which simulates one-dimensional pipe flow was constructed. The frictional forces were accounted for by the empirical concept of friction factor. For the fluid properties, software using empirically made correlations was used. To validate the numerical program, a comparison with previous experimental work was done. The agreement with experimental data was good for certain flow configurations, worse for others. From this it was concluded that further comparisons with experimental data must be made in order to tell the accuracy of the mathematical model and the correlations for fluid properties used. When using supercritical helium, thermo-hydraulic instabilities may arise in the cooling loop. It was of special interest to see how well a numerical program could simulate and predict this phenomenon. It was found that the numerical program did not function for such unstable conditions; in fact it was much more sensitive than what reality is. For the beam screen cooling system we conclude that to cope with the increased heat loads of future upgrades, an increase in pressure level is needed regardless if the coolant remains helium, or is changed to neon. Increasing the pressure level also makes that the problems with thermo-hydraulic instabilities can be avoided. Of the two coolants, helium gave the best heat extraction capacity. Unlike neon, it is also possible to keep the present temperature level when using helium.