The HERA RF-Driven Multicusp H− Ion Source

Abstract

The HERA RF‐Volume Source is the only source that has delivered routinely an H− current of 40 mA without Cs. The current has now been improved to 60 mA. While for HERA operation a pulse length of less than 200 μsec is necessary, operation with a pulse length of 3 msec was demonstrated at DESY in cooperation with SNS, FNAL and CERN.The physics of the extraction plasma region has been the subject of very detailed investigations with special sets of collars and different materials. Tests with plasma chambers of different sizes have been done. Significant changes have since been made in the source design. A more efficient RF coupling to the plasma was developed. Together with a new funnel system this source delivers higher H− currents and a lower H− /electron ratio. The high voltage and vacuum technology was improved and a new electron dump technique was introduced. The steps to a new improved source design are described in this paper.