Chapters authored
Pressure Inhomogeneities across Large Samples Using Gas Pressure Media at Low Temperatures
In-situ inert gas high pressure vessels for neutron scattering for pressures of up to 1.0 GPa, and temperatures as low as 1.5 K, pose a particular problem due to the P × T phase diagram of the pressure media. Hydrostatic pressure under constant pressure and volume, passing through the pressure versus temperature phase diagram (P × T) of the gas to achieve low temperatures (1.5 K < T < 30 K) will cause an overall pressure reduction at base temperatures of at most 25% of the pressure read at the P × T. A methodology for pressurization to ensure minimal pressure loss as temperature falls below the pressure media phase change and at the same time minimizing pressure inhomogeneity throughout the length of the sample is presented within this work. The technique proved to reduce the isochore loss of pressure by a factor of 5. Moreover, for the first-time direct experimental quantitative evidence of the reduction in pressure inhomogeneities across large samples is reported here, and the average inhomogeneity reduction in pressure across top and bottom of a 45 mm long sample is better than a factor of 3.
Part of the book: Boundary Layer Flows