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Full-Text Articles in Physical Sciences and Mathematics
Investigation Of Low-Stress Silicon Nitride As A Replacement Material For Beryllium X-Ray Windows, David B. Brough
Investigation Of Low-Stress Silicon Nitride As A Replacement Material For Beryllium X-Ray Windows, David B. Brough
Theses and Dissertations
The material properties of low stress silicon nitride make it a possible replacement material for beryllium in X-ray windows. In this study, X-ray windows made of LPCVD deposited low stress silicon nitride are fabricated and characterized. The Young's modulus of the LPCVD low stress silicon nitride are characterized and found to be 226±23 GPa. The residual stress is characterized using two different methods and is found to be 127±25 MPa and 141±0.28 MPa. Two support structure geometries for the low stress silicon nitride X-ray windows are used. X-ray windows with thicknesses of 100 nm and 200 nm are suspended on …
Development Of A Mevva Based Beryllium-7 Plasma Source, David K. Olson
Development Of A Mevva Based Beryllium-7 Plasma Source, David K. Olson
Theses and Dissertations
We have designed a new type of plasma gun ion source for a Malmberg-Penning trap based on Metal Vapor Vacuum Arc (MeVVA) ion source designs. Our primary intent with this MeVVA-type source is to create a confinable beryllium-7 (7-Be) plasma. 7-Be is a peculiar isotope due to its varying radioactive decay half-life in different electro-chemical configurations. It is also found in an unexpected abundance at high altitudes of the Earth's atmosphere. It is possible ioniziation affects the radioactivity of the isotope, partly explaining this discrepancy with atmospheric models. The short half-life of 7-Be requires us to replace the sample inside …