ATLAS 10 GHz electron cyclotron resonance ion source upgrade project

A major upgrade of the first ATLAS 10 GHz electron cyclotron resonance (ECR ) ion source, which began operations in 1987, is in the planning and procur ement phase. The new design will convert the old two-stage source into a si ngle-stage source with an electron donor disk and high gradient magnetic fi eld that preserves radial access for solid material feeds and pumping of th e plasma chamber. The new magnetic-field profile allows for the possibility of a second ECR zone at a frequency of 14 GHz. An open hexapole configurat ion, using a high-energy-product Nd-Fe-B magnet material, having an inner d iameter of 8.8 cm and pole gaps of 2.4 cm, has been adopted. Models indicat e that the field strengths at the chamber wall, 4 cm in radius, will be 9.3 kG along the magnet poles and 5.6 kG along the pole gaps. The individual m agnet bars will be housed in austenitic stainless steel, allowing the magne t housing within the aluminum plasma chamber to be used as a water channel for direct cooling of the magnets. Eight solenoid coils from the existing E CR will be enclosed in an iron yoke to produce the axial mirror. Based on a current of 500 A, the final model predicts a minimum B field of 3 kG with injection and extraction mirror ratios of 4.4 and 2.9, respectively. (C) 20 00 American Institute of Physics. [S0034-6748(00)57502-9].