A HYDRODYNAMIC MODEL OF THE NEGATIVE-ION SOURCE

Fluid equations are used to interpret the electron, positive- and negative-ion properties of a bucket source. Assuming an exponential dependence for the electron density in the axial direction, forms for the electric potential and electron temperature are derived. These are used to obtain expressions for the number density and current density profiles for each of the species in the plasma, and where possible compared with the Culham ion source results. Good qualitative (and some quantitative) agreement is established between the theoretical model and probe measurements of the plasma source properties.