Ion Beam Measurements of Cesium Recombination Cross Sections

The recombination cross sections of both atomic and molecular cesium ions have been measured using an ion-beam technique. An ion beam is passed through a modulated space-charge-neutralized electron cloud, and the emergent atoms and molecules are detected. This technique allows the molecular and atomic recombinations to be found independently. The atomic cross section at an effective electron temperature of 1540°K is found to be (1.7±1.2)×${10}^{-19\mathrm{}}$ ${\mathrm{cm}}^2$, corresponding to a recombination coefficient of (3.1±2.3)×${10}^{12}$ ${\mathrm{cm}}^3$/sec. The molecular recombination cross section at an effective electron temperature of 1380°K is (1.2±1.0)×${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$, corresponding to a recombination coefficient of (2.5±1.8)×${10}^{-8\mathrm{}}$ ${\mathrm{cm}}^3$/sec.