The Hera Volume H-Source

The HERA RF-Volume Source is the only source that delivers routinely a H^–current of 40 mA without Cs. It has been running for years without interruption for maintenance. The production mechanism for H^–ions in this type of source is still under discussion. Laser photodetachment measurements have been done at DESY in order to measure the H^–distribution in the source. The measurements were done also under extraction conditions at high voltage. The dependency of the quality of the H-beam H-beam H-beam on the frequency was investigated. A frequency range of 1.65 – 9 Mhz was scanned and the emittance was measured for several H-currents up to 40 mA. The results of our investigations make further source improvements possible. Recently currents of 60 mA were reached. The design of the source is explained and alternatives are discussed.