Secondary Electron Emissions from Metal Surface by High-Energy Ion and Neutral Atom Bombardments

To obtain ${\gamma }_e$ for ${\mathrm{H}}_2^{+}$ ion bombardment on metal targets, an expression for the secondary electron emission coefficient by fast positive ion bombardment is obtained after adopting a method of calculation similar to that employed by Sternglass. It is shown that the experimental values of ${\gamma }_e$ for ${\mathrm{H}}_2^{+}$ ion bombardment agree with the calculated values provided it is assumed that inside the target a hydrogen molecular ion is dissociated into a proton and a hydrogen atom, each having half the energy of the molecular ion. The dissociation cross section of a hydrogen molecular ion inside the target may be given by ${\sigma }_d=K\surd T$, where $K=1.2\mathrm{}$, ${\sigma }_d$ is expressed in units of ${10}^{-17\mathrm{}}$ ${\mathrm{cm}}^2$, and $T$ is in Mev.