An Investigation into the Gettering Powers of Various Metals for the Gases Hydrogen, Oxygen, Nitrogen, Carbon Dioxide and Air

Abstract

Measurements of the ``gettering'' or clean-up ability of aluminum, magnesium, thorium, uranium, misch metal, zirconium and barium for the common gases were made. In most cases the measurements were quantitative and represent gettering powers unassisted by an electric discharge or other source of ions. The effect of temperature conditions on the gettering and keeping properties of several of the getters is given. The superior gettering powers of the diffuse layers produced by vaporizing the getters in the presence of a gas, as compared to those of the bright getter deposits produced in a high vacuum were confirmed. Barium and misch metal were found to be the most active of the materials tried, and the convenient forms which barium is now commercially obtainable would seem to make it first choice for most work, though it is not effective in the presence of Hg vapor. Magnesium and aluminum showed little activity without the presence of a discharge. Thorium and uranium showed considerable activity for H2 and O2, but the high temperatures needed for flashing, make them rather inconvenient to use.