Determination of the interaction potential of the noble gases from shock wave structure experiments. Feasibility of a modified electron beam densitometer technique to measure diffusive separation in shock waves in helium-argon mixtures

• Main Author: Barcelo, Brian Thomas
• Format: Others
• Published: 1971
• Online Access: https://thesis.library.caltech.edu/1253/1/Barcelo_bt_1971.pdf; Barcelo, Brian Thomas (1971) Determination of the interaction potential of the noble gases from shock wave structure experiments. Feasibility of a modified electron beam densitometer technique to measure diffusive separation in shock waves in helium-argon mixtures. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/QH9Z-BH10. https://resolver.caltech.edu/CaltechETD:etd-04022009-092506 <https://resolver.caltech.edu/CaltechETD:etd-04022009-092506>

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Shock wave experiments were conducted in the GALCIT* seventeen-inch low density shock tube to measure the interaction potential of the following nonradioactive noble gases: neon, argon, krypton, and xenon. The experimental shock profiles obtained by employing the electron beam densitometer technique were compared to the Monte Carlo numerical simulation of the shock wave structure. The comparison determined the intermolecular potential for these gases, a potential assumed to be of the form [...] = const/r[superscript s]. The values resulting for the free parameter s in the inverse repulsive power law were 9, 10, 11, and 12 for xenon, krypton, argon, and neon, respectively. In a second phase of the experiments, the feasibility of a modified electron beam densitometer technique was investigated for measuring the shock wave structure in a binary mixture of helium and argon. It was desired to obtain both the argon and helium density profiles through the shock wave by varying the electron beam energy in two experiments of identical shock conditions (gas concentrations, Mach number, initial pressure, etc.). Theoretical calculations of the collision cross-section indicated only a slight possibility of separating the density profiles of the two species with the range of electron energy possible in the experimental apparatus (7000 to 15000 volts). Experiments conducted with initial gas concentrations of 10%, 20%, 50%, and 80% argon in shock waves with a Mach number of approximately four confirmed these suspicions but permitted qualitative conclusions in agreement with other similar investigations. *Graduate Aeronautical Laboratories California Institute of Technology.