Proton Production by Electron Collisions in Molecular Hydrogen

The collision processes leading to the production of protons by single electron collisions with molecular hydrogen were investigated. A mass spectrometer was used for the analysis. The electron beam, along which ions were produced, was coaxial with a cylindrical conductor, and the radial field within this conductor due to the electron space charge was used as an energy selector for the ions. The ions measured were those moving initially at right angles to the electron beam. The "fast" protons (ions having several electron volts of energy) found by Bleakney were observed, and a rough measurement of the cross section for their production was made. The cross section was found to reach a maximum of about 0.015 ${\mathrm{cm}}^2$/${\mathrm{cm}}^3$ for 110-volt electrons. No evidence was found for the slow protons observed by Bleakney. It is believed that these were formed by secondary collision processes. From the theory developed by Smith, it is possible to compute roughly the initial energy distribution of the ions. The distributions are in accord with the potential energy curves of the hydrogen molecule..