Comparison of the charge state distributions of electron cyclotron resonance ion sources working in high B mode at different frequencies

The behavior of the two superconducting electron cyclotron resonance ion sources of Michigan State University-National Superconducting Cyclotron Laboratory and of INFN-Laboratori Nazionali del Sud, operating respectively at 6.4 and 14 GHz is compared in this note. The charge state distributions present a similar shape, when both the sources are optimized for the production of high charge state ions. The beam intensity is roughly proportional to the square of the frequency which may be explained by the difference in plasma density. (C) 1998 American Institute of Physics.