A high intensity dc H− source for low energy injection

Abstract

While a 20 mA dc H− source system at 25–30 keV beam energy has been developed at TRIUMF several years ago, another recent demand on the system is to provide a 4 to 5 mA H− at the 4–6 keV energy range. We found that at this low energy range, the existing source/extraction system can only give ∼1 mA with poor emittance due to strong space-charge effect. Fortunately, a very special source/extraction mechanism together with the use of neutralization was discovered and developed to overcome this difficulty. Up to 4 mA with a normalized rms emittance of 0.15 π mm mr has been achieved at 6 keV. This performance finds its usefulness for injection systems where lower beam energy and higher beam intensity are required. A copy of the TRIUMF system was constructed and successfully tested in the summer of 2000 for the “H− Acceleration Project” for the K130 cyclotron at Jyväskylä University, Finland.