Cross sections and equilibrium charge fractions whenD2+is incident on Cs vapor

The total cross section for charge exchange or breakup when ${\mathrm{D}}_2^{+}$ is incident on Cs has been measured in the energy range 3.0-23 keV. The cross section has a value of (1362 ± 80) × ${10}^{-17\mathrm{}}$ ${\mathrm{cm}}^2$ at 3 keV and falls rapidly with increasing energy, reaching a value of (594 ± 40) × ${10}^{-17\mathrm{}}$ ${\mathrm{cm}}^2$ at 23 keV. The equilibrium fraction of ${\mathrm{D}}^{-}$ obtained when ${\mathrm{D}}_2^{+}$ is incident on Cs has also been measured. The equilibrium fraction of ${\mathrm{D}}^{-}$ is (10.5 ± 2.0)% at 3 keV, (7.3 ± 1.6)% at 5 keV, (3.4 ± 0.7)% at 11.5 keV, (2.0 ± 0.4)% at 17.3 keV, and (1.5 ± 0.3)% at 23 keV. The equilibrium fraction of ${\mathrm{D}}^{-}$ obtained when ${\mathrm{D}}_2^{+}$ is incident on Cs at an energy $E$ is shown experimentally to be the same as the equilibrium fraction of ${\mathrm{D}}^{-}$ obtained when ${\mathrm{D}}^{+}$ is incident on Cs at an energy $\frac{1}{2}E$. The angular distribution of the reaction products when ${\mathrm{D}}_2^{+}$ ions are incident on Cs includes appreciable scattering into angles which are larger than 1°. An explanation of these large scattering angles is offered.