Search

Additive manufacturing of high-quality copper using electron beam melting techniques has demonstrated significant progress toward suitability for production of vacuum electronics components. Additively manufactured low oxygen level copper wafers, as printed and annealed, have been tested in an RF cavity designed for surface resistivity measurements. Strings of coupled cavities for S-band and X-band traveling wave tubes have been designed for vertical additive manufacturing in powder bed systems, enabling significant cost reduction. The S-band RF cavity string design has been additively manufactured, processed and RF tested.

Quantum computers (QC), if realized, could disrupt many computationally intense fields of science. The building block element of a QC is a quantum bit (qubit). Qubits enable the use of quantum superposition and multi-state entanglement in QC calculations, allowing a QC to simultaneously perform millions of computations at once. However, quantum states stored in a qubit degrade with decreased quality factors and interactions with the environment. One technical solution to improve qubit lifetimes and network interactions is a circuit comprised of a Josephson junction-based qubit located inside of a high Q-factor superconducting 3D cavity.It is known that niobium resonators can reach $Q_{0}>10^{11}$Q0>1011. However, existing cavity geometries are optimized for particle acceleration rather than hosting qubits. RadiaBeam Technologies, in collaboration with Argonne National Laboratory and The University of Chicago, has developed a niobium superconducting radio frequency quarter-wave resonant cavity (QWR) for quantum computation. A 6 GHz QWR was optimized to include tapering of the inner and outer conductors, a toroidal shape for the resonator shorting plane, and an inner conductor tip to reduce parasitic capacitance. In this paper, we present the results of the resonator design optimization, fabrication, processing, and testing.

The absorption coefficient during pulsed, conduction-mode electron beam spot melting of 304 stainless steel was measured at different combinations of accelerating voltage [60,80] kV, beam current [10,15,20] mA, pulse length [0.6–12] mS and beam inclination angle [0, 15, 35, 55, 65]°. Ignoring evaporative and radiative heat loss, the absorption coefficient was determined directly by fitting in-situ thermocouple measurements to an analytical function, with an average adjusted R-square fit parameter of 0.9996 over the 103 measurements. The absorption coefficient was found to be insensitive to both beam current and accelerating voltage, but decreased with increasing inclination angle. Measurements are compared to estimates generated from Monte-Carlo electron trajectory simulations using the CASINO software, with good agreement for all process parameter combinations, experimentally demonstrating the capability of Monte-Carlo methods to estimate local electron beam heat transfer.

Ataxia-telangiectasia (A-T) is a recessive disorder caused by biallelic pathogenic variants of ataxia-telangiectasia mutated (ATM). This disease is characterized by progressive ataxia, telangiectasia, immune deficiency, predisposition to malignancies, and radiosensitivity. However, hypomorphic variants may be discovered associated with very atypical phenotypes, raising the importance of evaluating their pathogenic effects. In this study, multiple functional analyses were performed on lymphoblastoid cell lines from 36 patients, comprising 49 ATM variants, 24 being of uncertain significance. Thirteen patients with atypical phenotype and presumably hypomorphic variants were of particular interest to test strength of functional analyses and to highlight discrepancies with typical patients. Western-blot combined with transcript analyses allowed the identification of one missing variant, confirmed suspected splice defects and revealed unsuspected minor transcripts. Subcellular localization analyses confirmed the low level and abnormal cytoplasmic localization of ATM for most A-T cell lines. Interestingly, atypical patients had lower kinase defect and less altered cell-cycle distribution after genotoxic stress than typical patients. In conclusion, this study demonstrated the pathogenic effects of the 49 variants, highlighted the strength of KAP1 phosphorylation test for pathogenicity assessment and allowed the establishment of the Ataxia-TeLangiectasia Atypical Score to predict atypical phenotype. Altogether, we propose strategies for ATM variant detection and classification.

Modifications in the geometry of a superconducting RF cavity due to various processing procedures are presented in a convenient matrix formulation. Specifically, the effect of chemical etching, cooling down, and preloading are characterized, while the corresponding frequency shifts are calculated with a reliable software. This matrix method was used in the fabrication of the first cornell energy recovery linac (ERL) 7-cell cavity. Cavity fabrication can be broken down into three main stages: deep-drawing cups, welding the cups in pairs to obtain "dumbbells" and end groups, and, finally, welding the obtained components into a completed cavity. Frequency measurements and precise machining were implemented after the second stage. A custom RF fixture and data acquisition system were designed and validated for this purpose. The system comprised of a mechanical press with RF contacts, a network analyzer, a load cell and custom LABVIEW and MATLAB scripts. To extract the individual frequencies of the cups from these measurements, the established algorithm of calculations was analysed and corrected. Corrections for the ambient environment were also incorporated into the measurement protocol. Using the procedure presented, the frequency deviation of the completed 1.3 GHz 7-cell cavity was 360 kHz, corresponding to an average error about 75 μm in length for every cell.

International audience

In French, the local mixed enterprise corporation (SEML) have been involved in the regional development for 50 years but paradoxically most of the research about them deals with their legal nature. This thesis places the SEML into the crossed control work between the State, the Local Authorities and the Deposit and Consignment Office. First the State privileged tool, they have gradually taken refuge in the Local Authorities, together with the diversification of their fields of intervention. Thus they testify to the power stakes between decentralization and recentralization, free enterprise and social and economic control. Locally, governing methods and urban cultures have an influence on their role and their positioning, as attested by the analysis of the towns of Bordeaux, Rennes and Montpellier. The European influences feed the prospective debate with different experiences on urban planning, land ownership and the respective role of public and private participants, the SEML being part of both the movement of the European Local Public Enterprises and the Public Private Partnerships. Thus the contribution of this thesis lies in the approach of urban and territorial policies under the scrutiny of one of the operational participants in their implementation, being both a participant and a witness., En France, les Sociétés d'Economie Mixte Locales (SEML) participent depuis 50 ans à l'aménagement du territoire mais paradoxalement la plupart des recherches les concernant traitent de leur nature juridique. Cette thèse resitue les SEML dans les jeux de régulations croisées entre l'Etat, les Collectivités Locales et la Caisse des Dépôts et Consignations. D'outil privilégié de l'Etat elles sont passées progressivement sous l'égide des collectivités locales, accompagnant la diversification des champs d'intervention de celles-ci. Elles sont ainsi témoin des enjeux de pouvoir entre décentralisation et recentralisation, libéralisme et régulation économique et sociale. Localement, les modes de gouvernance et les cultures urbaines influent sur leur rôle et leur positionnement tel qu'en témoigne l'analyse des agglomérations de Bordeaux, Rennes et Montpellier. Les influences européennes alimentent le débat prospectif avec des expériences différentes de la planification urbaine, de la propriété foncière et du rôle respectif des acteurs publics et privés, les SEML s'inscrivant tout à la fois dans le mouvement des Entreprises Publiques Locales européennes et des Partenariats Public Privé. L'apport de cette thèse réside ainsi dans l'approche des politiques urbaines et territoriales avec le regard d'un des acteurs opérationnels de la mise en œuvre de celles-ci, tout à la fois acteur et témoin.