Calculation of State-Specific Rate Coefficients for Non-equilibrium Hypersonics Applications

Speaker: Richard L. Jaffe, Entry Systems Technology Division, NASA Ames Research Center
June 3, 2014

Presentation

Abstract

During entry of spacecraft into planetary atmospheres at hypersonic speeds the gaseous envelope surrounding the vehicle is heated to extreme temperatures and the atmospheric gases reach a new chemical equilibrium composition, often at a temperature between 6,000 K and 12,000 K. In order to accurately model this process, one must know rate coefficients or cross sections for the relevant collisional dissociation, exchange reactions and ro-vibrational relaxation. We have been using accurate theoretical methods to compute ro-vibrational state-specific rate coefficients needed to model the high-temperature chemistry for N₂-O₂ and CO₂-N₂ mixtures to describe Earth and Mars entry, respectively. This presentation will focus on dissociation and relaxation processes encountered during Earth entry at 8-12 km/s.

Biography

Richard Jaffe has a long career as a computational chemist at Ames Research Center. Currently, he is carrying out fundamental research in hypersonics—studying the detailed collisional processes that take place in the bow shock layer of spacecraft during atmospheric entry. During his tenure at Ames, he has applied computational chemistry methods to the study of atmospheric reactions, carbon nanotube-liquid interactions, materials science, polymer physics and spectroscopy. He has a Ph.D. in Physical Chemistry from Yale University was a post-doctoral research associate at the University of Rochester before coming to Ames.

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