Experimental investigation of first- and second-sound shock waves in liquid helium II

The cryogenic shock tube is used to generate a gasdynamic shock which propagates through saturated helium vapor and subsequently reflects from the upper surface of a column of LHeII. Superconducting thin-film detectors, produced by evaporation of aluminum in an oxygen atmosphere, yield highly repeatable arrival time data for the incident gasdynamic shock and the resultant first- and second-sound shocks in the liquid. Accurate x-t diagrams of the shock trajectories have been constructed for initial liquid temperatures of T(0) = 1.522, 1.665, 1.751, 1.832, 1.989, 2.031, and 2.095°K. Consistent discrepancies are observed between experimental and theoretical wave trajectories. The detector signals qualitatively verify theoretical predictions that the temperature decreases through the pressure shock and increases through the temperature shock. Amplitude measurements based on static detector calibrations indicate that the magnitude of the temperature jump across the pressure shock agrees approximately with the theoretical calculation. Temperature jump measurements for the coupled second-sound shock imply shock-induced relative velocities, w =v(n)-v(s), on the order of 2.5 m/sec. For initial conditions close to the [lambda]-transition (e.g., T(0) = 2.095°K), the pressure jump across the first-sound shock is sufficient to cause a change in phase from LHeII to LHeI. This change is experimentally evidenced by detector outputs indicating the absence of the temperature shock in the wake of a sufficiently strong pressure shock

Development of a system to provide diagnostics-while-drilling.

This report describes development of a system that provides high-speed, real-time downhole data while drilling. Background of the project, its benefits, major technical challenges, test planning, and test results are covered by relatively brief descriptions in the body of the report, with some topics presented in more detail in the attached appendices

Art in Victoria : 1960-1986

The authors describe the arts in Victoria since 1945, focusing on the role of art galleries and art schools and on the work of individual artists. Includes 75 artists' statements and biographical notes