A NEW 14 GHZ ELECTRON-CYCLOTRON-RESONANCE ION-SOURCE FOR THE HEAVY-ION ACCELERATOR FACILITY ATLAS

A 14 GHz electron-cyclotron-resonance (ECR) ion source has been design ed and built at Argonne National Laboratory. The source is a modificat ion of the AECR [D. J. Clark, C. M. Lyneis, and Z. Q. Xie, 14th Partic le Accelerator Conference (PAC), IEEE Conference 91 CH3038-7, 1991 (un published), p. 2796 and C. M. Lyneis, Z. Q. Zie, D. J. Clark, R. S. La m, and S. A. Lundgren, 10th International Workshop on ECR Ion Sources, Oak Ridge, ORNL CONF-9011136, 1990 (unpublished), p. 47.] at Berkeley and incorporates the latest results from electron-cyclotron-resonance (ECR) developments to produce intense beams of highly charged ions, i ncluding an improved magnetic confinement of the plasma electrons with an axial mirror ratio of 3.5. The aluminum plasma chamber and extract ion electrode as well as a biased disk on axis at the microwave inject ion side donate additional electrons to the plasma, making use of the large secondary electron yield from aluminum oxide. The source is capa ble of ECR plasma heating using two different frequencies simultaneous ly to increase the electron energy gain for the production of high cha rge states. The main design goal is to produce several e mu A of at le ast U-238(35+) in order to accelerate the beam to coulomb-barrier ener gies without further stripping. First charge state distributions for g aseous elements have been measured and 210 e mu A(16)O(7+) has been ac hieved. A normalized, 90% emittance from 0.1 to 0.2 pi mm mrad for kry pton and oxygen beam has been found.