Radiation absorption of propellant gas [in electrothermochemical launchers]

Plasma radiation plays an important role in ETC concepts for improving gun performance. A significant part of the electrical energy added into the charge chamber is converted into radiation. The interaction of radiation with a solid propellant can cause an enhanced burning or a temperature compensated ignition. Both effects have been experimentally observed and reported by various research groups. In gun applications with electrical ignition (ETC gun) the reaction products of the propellant, the propellant gases, are normally located between the radiation source and the solid propellant. These molecules can absorb a significant part of the irradiated energy especially in the UV region of spectrum. Thus, the optical properties of the propellant gas define the efficiency of the interaction between plasma radiation and the solid propellant surface. Experimental results of interaction at high pressure in a closed vessel between the pulsed electrical discharge and the propellant gas are presented. It is shown that the observed increase of pressure due to the absorption of radiation in the propellant gas is in good agreement with the results of the numerical simulations. These calculations are based on the iterative solution of the time-dependent magnetohydrodynamic equations and the radiation transport equation.