Progress report of the third Generation ECR ion source fabrication

Recent progress in the construction of the 3rd Generation ECR ion source at the 88" cyclotron in Berkeley is reported. Test results of a full scale prototype superconducting magnet structure, which has been described in the last ECR Ion Source Workshop, lead to an improved coil design for the 3rd Generation ECR ion source. Solenoids of the new design have been fabricated and exceeded the design field values without quench. The new sextupole coils are currently being wound and will be tested this summer. This magnet structure consists of three solenoids and six race track coils with iron poles forming the sextupole. It is described in the report along with the structural support and coil winding specifications. The coils are designed to generate a 4T axial mirror field at injection and 3T at extraction and a radial sextupole field of 2.4 T at the plasma chamber wall. The high axial magnetic field of the 3rd Generation ECR ion source influences ion beam extraction considerably and we have initiated simulations of the extraction and beam transport system in order to enhance transmission through the injection beam line of the 88" cyclotron.