CHARGE-EXCHANGE COLLISIONS BETWEEN HYDROGEN IONS AND CESIUM VAPOR IN ENERGY RANGE 3 NS AND CESIUM VAPOR IN ENERGY RANGE 0.5-20 KEV

Charge-exchange collisions have been studied when H+ ions and ground state H0 atoms are incident on Cs vapor. Measurements of the positive, neutral, and negative beam components after passage through the target were made as a function of the Cs target thickness at several energies between 0.5 and 20 keV. All three beam components were found to approach charge equilibrium monotonically. The maximum H- equilibrium yield is (21 ± 4)%, which occurs at an H+ energy of 0.75 keV. The H- yield decreases with increasing energy, and is 0.4% at 20 keV. At energies below 4 keV the H+ equilibrium yield is very small compared with the yield of H0 and H-. For energies greater than 10 kev the H- equilibrium yield is very small compared with the yield of H0 and H+. The cross sections σ+0, σ+-, σ0+, and σ0- were measured. The subscripts + and - refer to the H+ and H- ions, 0 as an initial subscript refers to a ground-state H0 atom, and 0 as a final subscript refers to an H0 atom in the particular states produced. The cross section σ+0 decreases with increasing energy, and ranges from (9.4 ± 2.0) × 10-15 cm2 at 1 keV to (7.5 ± 1.1) × 10-16 cm2 at 15 keV. The cross section σ+- decreases with increasing energy in the range 2-15 keV, and has the value (2.1 ± 0.6) × 10-17 cm2 at 5 keV. The cross section σ0+ increases with increasing energy, having the value (1.2 ± 0.2) × 10-17 cm2 at 2 keV, and (1.74 ± 0.26) × 10-16 cm2 at 15 keV. The cross section σ0- decreases with increasing energy, having the value (1.5 ± 0.3) × 10-16 cm2 at 2 keV and (1.4 ± 0.2) × 10-17 cm2 at 15 keV. © 1969 The American Physical Society.