Numerical study of cesium effects on negative ion production in volume H-and D- ion sources

We present the results of model calculation on H-/D- isotope effects in the tandem volume source. The model includes the surface production due to cesium injection. On the electron density ne dependence of H-/D-production, we have observed an interesting phenomena. Namely D- production, i.e D- density, is higher than H- production in low ne, but in high ne H-production is higher than D- production. The atomic density plays an important role in the density inversion between H- and D- ions. (author)