Passive Measurement of Hydrogen Ground State Rotational and Vibrational Temperatures in Kinetic Plasmas

D.R. Farley, D.P. Ludberg and S.A. Cohen

关键词: APPROXIMATIONS;    BORN APPROXIMATION;    DISTRIBUTION;    ELECTRONS;    EXCITATION;    GROUND STATES;    HYDROGEN;    KINETICS;    PLASMA;    QUADRUPOLES;    SPECTRA;    SYMMETRY Hydrogen;    Diagnostics;    Optical Spectroscopy;   

DOI  :  10.2172/988887
RP-ID  :  PPPL-4548
PID  :  OSTI ID: 988887
Others  :  TRN: US1007027

学科分类：原子、分子光学和等离子物理

美国|英语

来源: SciTech Connect

【 摘 要 】

A dipole-quadrupole electron-impact excitation model, consistent with molecular symmetry rules, is presented to fit ro-vibronic spectra of the hydrogen Fulcher-?? Q-branch line emissions for passively measuring the rotational temperature of hydrogen neutral molecules in kinetic plasmas with the coronal equilibrium approximation. A quasi-rotational temperature and quadrupole contribution factor are adjustable parameters in the model. Quadrupole excitation is possible due to a violation of the 1st Born approximation for low to medium energy electrons (up to several hundred eV). The Born-Oppenheimer and Franck-Condon approximations are implicitly shown to hold. A quadrupole contribution of 10% is shown to fit experimental data at several temperatures from different experiments with electron energies from several to 100 eV. A convenient chart is produced to graphically determine the vibrational temperature of the hydrogen molecules from diagonal band intensities, if the ground state distribution is Boltzmann. Hydrogen vibrational modes are long-lived, surviving up to thousands of wall collisions, consistent with multiple other molecular dynamics computational results. The importance of inter-molecular collisions during a plasma pulse are also discussed.