Ion source for neutral beam injection meant for plasma and magnetic field diagnostics.

At the Lawrence Berkeley National Laboratory a diagnostic neutral beam injection system for measuring plasma parameters, flow velocity, and local magnetic field is being developed. The system is designed to have a 90% proton fraction and small divergence with beam current at 5-6 A and a pulse length of approximately 1 s occurring once every 1-2 min. The ion source needs to generate uniform plasma over a large (8 x 5 cm(2)) extraction area. For this application, we have compared rf driven multicusp ion sources operating with either an external or an internal antenna in similar ion source geometry. The ion beam will be made of an array of six sheet-shaped beamlets. The design is optimized using computer simulation programs.