Development of H/sup -/ sources at Brookhaven National Laboratory

Negative hydrogen ion sources have been developed at Brookhaven National Laboratory for several years, with the initial goal to design a source for accelerator applications and later on to design a large unit for applications in neutral beam injectors of magnetic fusion devices. Three types of sources were investigated, a hollow discharge duoplasmatron yielding H/sup -/currents up to 60 mA, a Penning source yielding H/sup -/ currents up to 440 mA, and a magnetron source yielding H/sup -/ currents up to 1 A. All sources operate with a mixture of hydrogen gas and cesium vapors, and H/sup -/ ions are most likely produced on cesium covered electrode surfaces. A larger model of a Penning/magnetron source was constructed and will be tested soon; it incorporates among other new features a system for the cooling of the cathode