Computational model of collisionalradiative nonequilibrium plasma in an airdriven type laser propulsion
Abstract
A thrust power of a gasdriven laserpropulsion system is obtained through interaction with a propellant gas heated by a laser energy. Therefore, understanding the nonequilibrium nature of laserproduced plasma is essential for increasing available thrust force and for improving energy conversion efficiency from a laser to a propellant gas. In this work, a timedependent collisionalradiative model for air plasma has been developed to study the effects of nonequilibrium atomic and molecular processes on population densities for an airdriven type laser propulsion. Many elementary processes are considered in the number density range of 10^{12}/cm^{3}≤N≤10^{19}/cm^{3} and the temperature range of 300 K≤T≤40,000 K. We then compute the unsteady nature of pulsively heated air plasma. When the ionization relaxation time is the same order as the time scale of a heating pulse, the effects of unsteady ionization are important for estimating air plasma states. From parametric computations, we determine the appropriate conditions for the collisionalradiative steady state, local thermodynamic equilibrium, and corona equilibrium models in that density and temperature range.
 Publication:

Beamed Energy Propulsion: 6th International Symposium
 Pub Date:
 May 2010
 DOI:
 10.1063/1.3435431
 Bibcode:
 2010AIPC.1230..148O
 Keywords:

 radiative transfer;
 plasma interactions;
 plasma density;
 excited states;
 47.70.Mc;
 52.38.Mf;
 52.25.Dg;
 31.50.Df;
 Radiation gas dynamics;
 Laser ablation;
 Plasma kinetic equations;
 Potential energy surfaces for excited electronic states