Initiation of Chemical Reactions in Energetic Materials Using Plasmas and Arc Channels.

摘要

Experiments were conducted to determine the spatial and temporal distribution of the plasma temperature, pressure, number density, and velocity in the plasma-flow-field of an electrothermal source. The experiments revealed a decreasing plasma pressure, plasma temperature and plasma number density as plasma is leaving the capillary source and expands in air. The plasma jet velocity 2 inches from the source exit was found to be about 1300 m/s. Following plasma flow-field characterization, a set of experiment were conducted on the plasma-propellant interaction with increased propellant bed temperature. Experiments were conducted on JA-2 solid propellant with controlled bed temperature. Obtained results were used to develop a semi-empirical model that includes the bed temperature. Increased burn rates were observed with increased bed temperature, which appears to follow a power BR = A P(sup a) (T/T ambient) (sup b). Further investigation on plasma parameters, through optical emission spectroscopy measurements, allowed modifying the model to include plasma radiative heat flux and plasma number density in the proposed model. Arc channels were initiated in the central perforation of the propellant sample using two arc energy regimes, low and medium energies. The low energy, milli- joule range, has shown weight change of +/- 0.03 mg. Medium energy range between 260 and 1050 joules has shown an increased weight loss (increased burn rate) with increased arc energy. Experimental data has a linear fit Am = 2 x 10(exp - 4) (E + 282), where delta m is the mass loss in mg and E is the arc energy in joules. The linear fit has R(sup 2) (caret) 0.91. Arc modeling using approximated modified Coulomb logarithm has shown over-prediction of arc plasma parameters, as seen from arc temperature calculated by the model when compared to spectral results.