Internal energy relaxation in nitrogen plasmas

Kinetics;The State-to-State Vibrational and Rotational kinetics of the nitrogen mixture is modeled;Computational fluid dynamics (CFD);Computational methods for modeling hypersonic reactive flows;Chemistry;Chemical modeling of atmospherical re-entry conditions

Heritier, Kevin ; Panesi ; Marco

关键词: Kinetics;    The State-to-State Vibrational and Rotational kinetics of the nitrogen mixture is modeled;    Computational fluid dynamics (CFD);    Computational methods for modeling hypersonic reactive flows;    Chemistry;    Chemical modeling of atmospherical re-entry conditions;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/49582/Kevin_Heritier.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This work discusses the chemical kinetics of nitrogen molecules relaxing in a heat bath at constant temperature in a background gas composed of electrons and nitrogen atoms. The QCT (Quasi-Classical Trajectory) model recently developed at NASA Ames Research Center is used to study energy transfers and population distribution of nitrogen molecules due to collisions with atoms. An ab-initio model developed at the University College London (UCL) is used to study electron impact excitation. Initially, the chemical reactor is filled with cold gas which is suddenly heated up by several thousands of degrees Kelvin to reproduce strong non-equilibrium conditions. The large differences between translational and internal energy in the gas mixture promote energy transfers between the different internal states of the molecules. This work aims at studying the population of the internal states of the nitrogen molecules and the time evolution of the internal energy modes in order to construct a model for atmospheric re-entry conditions. Different assumptions will be made in order to quantify the free electron temperature. In literature,this temperature is often chosen to be equal to the translational temperature. This hypothesis will be discussed and compared to a new model that compute the electron temperature based on the conservation the free electron energy.