Aspects of the continuous wave, optically pumped H- ion source at TRIUMF

After reconstruction within a superconducting solenoid, the TRIUMF optically pumped H- ion source is now operational and has provided 5 μA of proton beam with 50% polarization extracted from the TRIUMF cyclotron. During the development of the source several types of extraction systems for the proton ECR source have been explored. Among different kinds of extraction electrodes a three-electrode, small hole grid system driven in an accel-accel mode has been found to be advantageous in providing stable operation with a maximum of beam at a very specific setting. A Na polarization above 70% has been achieved for a Na thickness of less than 5x1013 atoms/cm2. The final polarization is lowered due to the presence of a significant unpolarized background beam and due to the presence of the proton beam in the optically pumped Na vapour. (author)