A study of arc column rotation in a 4 ring ac arc heater without an external magnetic field is presented. Arc column speed is found to depend upon arc current, arc heater pressure, amount and direction of air injection and electrode geometry. The methods used for the experiments and the evaluation of the filmed data are described and justified. Arc heater efficiency and stability has been improved as a result of this work. (Author).
The design and performance of a four-ring three-phase ac ARC Heater are described. Successful operation at pressures of 10 to 33 atmospheres, temperatures of 2000 to 5000 degrees K and efficiencies of 25 to 60 percent has been demonstrated. Improvements in heater components will allow pressures of 70 atmospheres to be obtained. (Author).
A study of arc column rotation in a 4 ring ac arc heater without an external magnetic field is presented. Arc column speed is found to depend upon arc current, arc heater pressure, amount and direction of air injection and electrode geometry. The methods used for the experiments and the evaluation of the filmed data are described and justified. Arc heater efficiency and stability has been improved as a result of this work. (Author).
Three avenues for increasing the enthalpy attainable from scalable high performance arc heaters were studied: radiation loss reduction, magnetic control of arc terminations and geometry changes. The radiation loss work showed centerline arc column enthalpies over 30,000 Btu/lb. Because the arc column is optically thin, substantial reduction of radiation loss seems infeasible. Large arc devices will be limited more by radiation than small. Modest improvements in performance were achieved with magnetic interactions, which were found to be extremely complex. Proper proportioning of radial and axial field components was quite important, especially in maintaining scalability. Marked undesirable effects occurred when the auxiliary field coil was located near the electrode gap. Distinct performance improvements were achieved by changes in geometry, with air injection and chamber design the most significant for the low flow, high current region studied. (Author).
It is well established that population inversions between the (001) and (100) vibrational energy levels of CO2 can be created by rapid expansions of CO2-N2-H2O or He mixtures through supersonic nozzles. New experimental results are presented for such inversions. These experiments were conducted in both the 3-Megawatt Arc Tunnel and the 12.7 cm Shock Tunnel at the Naval Ordnance Laboratory. The results support previously published theoretical predictions obtained with a numerical, time-dependent, nonequilibrium nozzle flow analysis employing a simplified vibrational kinetic model. This theory is also compared with experimental data obtained by other investigators. (Author).
Gasdynamic Lasers: An Introduction is a 12-chapter introductory text to major development generations of gasdynamic lasers, focusing on their underlying physical and fundamental aspects. The opening chapters discuss the basic detailed physical phenomena that ultimately are responsible for producing gasdynamic laser action and the methods of calculating the performance of these devices. These topics are followed by a chapter on confirmation of the performance calculations through arc and shock tunnel experiments. The discussion then shifts to vibrational relaxation process behind normal shock waves in CO2-N2-He mixtures and assesses their population inversions occurring in the nonequilibrium flow. Other chapters explore the concepts of downstream mixing and optical cavity in gasdynamic lasers, as well as the laser beam extracted from these devices. A systematic study of aerodynamic windows that use supersonic flow across the aperture is presented in the concluding chapters, along with the phenomena associated with gasdynamic laser diffusers. This introductory text will be of great value to professional scientists and engineers, as well as to students and workers in the field who are interested in interdisciplinary applied science.
