Spectroscopic Diagnostics of Thermochemical Nonequilibrium Hydrogen Plasma Flow

Abstract

A method to diagnose thermochemical nonequilibrium hydrogen plasma flow nonintrusively by emission spectroscopy has been developed. The rotational, vibrational, and electron temperatures have been obtained by the preprocessed line intensity fitting of Fulcher- band of molecular hydrogen, and the degree of dissociation by the actinometry. In the preprocessed line intensity fitting, the temperatures are guessed on the basis of the similarity of Boltzmann distribution to make the searching domain smaller. As a result, it has become possible to identify the plasma temperatures more easily. Then our method has been applied to the inductively coupled plasma wind tunnel todeterminethefreestreamconditions.Theobtainedtotalenthalpy,whichiscomposedoftheinternalenergy,kinetic energy, and chemical energy, shows a reasonable tendency to be almost inversely proportional to the mass flow rate under the condition of fixed input power. The possible error in the temperatures, the degree of dissociation, and the total enthalpy is evaluated in the component-by-component manner. Nomenclature A = transition probability C = excitation rate coefficient Ethre = threshold energy F = rotational energy G = vibrational energy h = Pranck constant I = emission intensity J = rotational quantum number k = Boltzmann constant N = number density ne = electron number density Ri = Gas constant of ith speices Te = electron temperature Tele = electronic excitation temperature Trot = rotational temperature Ttra = translational temperature Tvib = vibrational temperature Y = mass fraction v = vibrational quantum number � = degree of dissociation � = frequency