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.

Photoelectron emission from metal surfaces induced by VUV-emission of filament driven hydrogen arc discharge plasma

“…The LIISA (Light Ion Ion Source Apparatus) ion source is a TRIUMFtype DC (tantalum) filament-driven multi-cusp arc discharge volume production ion source. LIISA is designed to provide up to 3 mA of H − at 5.9 keV injection energy to the JYFL K130 cyclotron [7]. The typical beam requirement of approximately 1 mA is reached with 70 V / < 10 A discharge voltage / current.…”

“…The line-of-sight plasma volume was limited by the 9.5 mm diameter puller electrode aperture and the (6 mm / 8 mm diameter) collimator between the target and the plasma. The target materials used in this study are metals which are typically found in negative hydrogen ion sources as chamber materials (Al, Cu, SS) [8,9,10], filament materials (Ta) [7,11], plasma grid materials (Mo) [12] or so-called collar materials (SS, Mo) [13,14]. The effect of Al, Cu and SS wall materials and Ta covered walls on the volume production of negative hydrogen ions has been studied in [3,15,16].…”

Hydrogen plasma induced photoelectron emission from low work function cesium covered metal surfaces

“…The measurements were performed with a filament-driven multi-cusp arc discharge plasma generator, which is a commonly used technology in volume production H À ion sources, e.g., LIISA H À ion source at JYFL. 31 The vacuum chamber is evacuated down to 10 À8 mbar background pressure with a 880 ls À1 turbomolecular pump before introducing 99.9999% purity hydrogen into the discharge volume. 70 V/4 A arc discharge voltage/current (280 W discharge power) and a plasma chamber (hydrogen) pressure of 2 Â 10 À2 mbar were used in the measurements.…”

Ion source research and development at University of Jyväskylä: Studies of different plasma processes and towards the higher beam intensities

“…In order to have enough space for new 18 GHz ECRIS, the filament driven H − ion source (called LIISA), 16 6.4 GHz ECRIS, 17 and 14 GHz ECRIS have to be relocated. The JYFL 14 GHz ECRIS was moved close to the 90…”