ELECTRIC ARCS IN TURBULENT FLOWS, III

Work is reported on the development of methods to measure arc temperature, axial pressure gradient, plasma flow velocity and radiative heat flux in long cylindrical turbulent arcs. Axis temperature and radial temperature distribution of laminar and turbulent 50 amp. nitrogen arcs of 11.2 atm. pressure were found to be of similar size, with some reservation about the accuracy of the 'side on' turbulent temperature measurement. The problem of measuring average turbulent arc temperatures was discussed; measurements in 'end on' observation and the use of the Milne-Larentz method appear to give better results than 'side on' observation of absolute line intensities. Measurements of the pressure gradient in a 11.2 atm., 125 amp. argon arc show a 1.8 power dependence of pressure gradient on flow rate, indicating that this relationship, well known from cold flow experiments, also holds under the conditions of the experimental arc temperatures. Plasma velocities were measured by time sequential photography of the turbulent arc structure. (Author)