ABSTRACT
The effect of impurities m a recombining plasma was studied by use of a coated aluminum slab. Materials of gold and nickel were coated on an aluminum slab with the thickness of 1000Å and 3000Å by evaporation, in order to observe the effect of atomic number dependence on radiation cooling The gold impurity had a strong cooling effect compared with Ni. The thickness of 3000Å and 1000Å were so thick that strong aluminum spectral lines could not be produced Chromium impurity was used to study the thickness effect on the gain coefficient of Al XI 105.7Å.. The intensity of Al XI 105.7Å linearly increased with the plasma length for all Cr thicknesses. No gain were observed in our experimental conditions.
