Development of RF-driven negative hydrogen ion source for J-PARC

Ueno, Akira  ; Namekawa, Yuya; Okoshi, Kiyonori ; Ikegami, Kiyoshi*; Takagi, Akira*; Oguri, Hidetomo  ; Yamazaki, Saishun

In order to achieve the design beam power of 1MW, a negative hydrogen ion source with a peak beam current of 60 mA is under development. The status of an rf-driven source using an rf-antenna developed at SNS of ORNL (Oak Ridge National Laboratory) is reported. The beam extraction system is the same with the J-PARC ion source, which is using a lanthanum hexaboride (LaB6) filament. The inner diameter of the plasma chamber is enlarged form 100 mm to 120 mm in order to install a water cooled plate attached to the plasma electrode (PE) and a cesium (Cs) oven. The end flange is modified to install the rf-antenna. A rod-filter flange is installed to produce a low-temperature plasma around the PE. In the conditions of the pulsed rf duty of 2.5%(1ms25Hz), Cs oven temperature of 175 C and the water cooled PE (PE temperature of 33 C), a negative hydrogen ion beam with a peak beam current of 60 mA is successfully produced.