Excitation Temperature in Time-Resolved Spectra of Single Condensed Spark Discharges*

From relative intensities of Fe I lines, a study has been made of the excitation temperatures in short-time high current condensed spark discharges, both in the integrated light from single sparks and from time-resolved spectrograms. In all cases a Boltzmann distribution of the atoms among the various excited energy-states has been found to exist, with the temperature as the distribution parameter. A statistical equilibrium between the electron gas and the excited atoms is presumed to exist, in which case the excitation temperature is the temperature of the electron gas. The spectrum of the initial phase of the spark is characterized by short-lived broadened lines of N II and O II. During the latter phase of the discharge (4–14 microseconds), in spite of extreme variations in current and radiation intensity from the source, the temperature was found to be approximately constant (6000–7000°K) both for damped and oscillatory discharges.