Measurement of the argon continuum radiation in the near vacuum ultraviolet

Absolute argon continuum emission coefficients have been measured from 330 nm down to 110 nm in the near v.u.v. The radiation originates from a stationary 1 atm arc plasma with temperatures between 16900 and 21500 K. At these high temperatures, single ionization is almost complete and the plasma contains also a number of doubly ionized particles. These cause very intense recombination edges around 120 nm, which have been included in a recent theory. The agreement with these calculations is very good throughout the spectrum for lower plasma temperatures. Measurements at higher temperatures confirm only the results for the Ar(II) edges around 120 nm. At higher wavelengths the experimental values lie above the theoretical ones and do not show the predicted structure. This discrepancy may be partly due to omissions in the calculations and partly to line wing problems in the experiment.