Keywords: SpectroscopyResearch 019.jpg One fearture a special feedback system to keep the spectral lines at a constant intensity resulted in greatly improved accuracy in measurements taken from the resulting spectra Iron was introduced to the plasma by flowing argon over heated ferric chloride in the large resistively wired tubes extending horizontally- one being held by Dr Bridges Additional smaller tubes were used for the water-cooling or gas flow systems National Institute of Standards and Technology 1970-07-20 National Institute of Standards and Technology PD-USGov-NIST PD-USGov National Bureau of Standards National Institute of Standards and Technology Spectroscopy |