The Effect of Space Charge Force on Beams Extracted from Ecr Ion Sources.

A new 3 dimensional ray tracing code BEAMenspace 3D, with a simple model to calculate the space charge force of multiple ion species, is under development and serves as a theoretical tool to study the ECRIS beam formation. Excellent agreement between the BEAMenspace 3D calculations and beam profile and emittance measurements of the total extracted helium 1+ beam from the RTECR ion source was obtained when a low degree of beam neutralization was assumed in the calculations. The experimental evidence indicates that the positive space charge effects dominate the early RTECR ion source beam formation and beamline optics matching process. A review of important beam characteristics is made, including a conceptual model for the space charge beam blow up. Better beam transport through the RTECR beamline analysis magnet has resulted after an extraction geometry modification in which the space charge force was more correctly matched. This work involved the development of an online beam characteristic measuring apparatus which will also be described.