Energetic Hydrogen Atoms in High Frequency Plasmas

摘要

Generation of energetic hydrogen atoms, with energy in the range 4-8 eV, was detected throughout the volume of a surface wave generated (500 MHz) plasma column in H_2 at pressure p = 0.01 mbar. The H_β, H_γ, H_δ, and H_ε, line profiles were found to be bi-Gaussian towards the plasma column end. The kinetic temperatures corresponding to the Doppler broadening of the H_β, H_γ, H_δ, lines are higher than the rotational temperature of the hydrogen molecular Fulcher-α band and the wall temperature. At pressure p = 0.2 mbar, the kinetic temperature of excited H (n = 4-7) atoms, as determined from the fitting of the spectral lines with a single-Gaussian profile, increases with upper level principal quantum number. The experimental results have been analyzed in the framework of a global self-consistent kinetic model describing this surface wave sustained plasma column.