IONIZATION IN SEEDED DETON by

It has been reported that equilibrium ionization is achieved in about 20 microseconds behind oxy-hydrogen and oxy-acetylene detonation waves (1), and that the electrical conductivity of the gas behind the detonations is of the order of 10-) mhos/cm. To obtain magnetohydrodynamic interaction with reasonable magnetic fieldsconductivities of the order of 10 mhos/cm are required of combustion gases. This thesis reports on an investigation of oxy-acetylene detonations at 1/10 atmosphere initial pressure, which were seeded with Potassium Acetylide (C2HK) to obtain the high conductivity mentioned above. Finely ground Potassium Acetylide was injected into the initial mixture and the concentration of the resulting aerosol was determined by a sedimentation technique. The electrical conductivity was determined by a magnetohydrodynamic interaction method developed by Lin et al (4). The measured conductivities were plotted as a function of the mole per cent of Potassium added and compared with the results of thermodynamic equilibrium calculations. Predicted and measured conductivities have approximately the same dependence on the concentration of Potassium, which was varied from 0.1 per cent to 10 per cent. Absolute values agreed within a factor of two, the agreement improving with increasspg mole fraction of Potassium; an extrapolated value of 10-19 sq cm being used for the electron-gas collision cross section in the calculation of the conductivity. There is some uncertainty in this value, and a value twice this gave good agreement between theory and experiment. The maximum measured conductivity was 2.7 mho/cm and occurred at about 3 mole per cent Potassium in the product gases. Thesis Supervisor: J. A. Fay Title: Associate Professor of Mechanical Engineering