Filament lifetime test of the negative ion source for the high intensity proton accelerator

Oguri, Hidetomo  ; Namekawa, Yuya*

The high intensity proton accelerator facility project (J-PARC) aims to pursue frontier science in materials science, nuclear physics and nuclear technology, using an accelerator complex at the highest beam power in the world. An H ion source for the project is required to produce a beam current of 60 mA and an emittance of 0.20 mm.mrad with a duty factor of 2.5 %. In addition, the ion source must be run for 500 h continuously without maintenance. As a result of the beam test, the beam current and the emittance of 72 mA and 0.15 mm.mrad were achieved in the Cs seeded operation, respectively. Because a lifetime of the filament cathode is one of the main restrictions for the maintenance cycle, we started to perform a filament lifetime test. As the result of the test, we succeeded for 258 h arc operation at the arc power of 30 kW with the duty factor of 3 %. Moreover, the results showed that there is a possibility of achievement 800 h lifetime by change the connection between filament and arc power supply and the optimization of the filament shape.