Advances in the Ion Source Research and Development Program at ISIS

This paper covers the advances in the ion source research and development Program at ISIS over the last 2 years. The work is a combination of theoretical finite element analysis calculations and experiments conducted on a purpose built development rig. The broad development goals are higher beam current with longer pulse length. A Finite Element Analysis (FEA) model is used here to understand the steady state and dynamic thermal behavior of the source, and to investigate the design changes necessary to offset the extra heating. Electromagnetic FEA modeling of the extraction region of the ISIS H- ion source has suggested that the present set up of extraction electrode and 90 deg sector magnet is sub-optimal, with the result that the beam profile is asymmetric, the beam is strongly divergent in the horizontal plane and there is severe aberration in the focusing in the vertical plane. The FEA model of the beam optics has demonstrated that relatively simple changes to the system should produce a dramatic improvement in performance. The theoretical and experimental results are compared here.