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

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

Princeton University. Plasma Physics Laboratory.

关键词: Approximations;    Spectra;    Hydrogen, Diagnostics, Optical Spectroscopy;    Excitation;    70 Plasma Physics And Fusion Technology;   

DOI  :  10.2172/988887
RP-ID  :  PPPL-4548
RP-ID  :  DE-AC02-09CH11466
RP-ID  :  988887

美国|英语

来源: UNT Digital Library

【 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-α 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.