Cesium seeding experiment for J-PARC H ion source

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

The J-PARC H ion source succeeds in producing a beam current of 38 mA without seeding Cs. It satisfies the requirement of the J-PARC 1st stage in which a beam power will be 0.6 MW. However a beam current of more than 60 mA is necessary for the J-PARC 2nd stage in which a beam power will be 1 MW. Therefore, two R&D(research and development)'s are being carried out in order to increase the beam current. One is without seeding Cs and the other is with seeding Cs. In the latter R&D, a beam current of 70 mA is produced with a W-filament and an arc-power of 15 kW. The low arc-power, will be helpful for reducing the Cs consumption rate. The lower Cs consumption rate is necessary for the stabler operation against sparking in high voltage gaps. The practicability of the ion source with seeding Cs is examined by optimizing the filament material and shape, the Cs seeding system including the temperature control of each part of plasma chamber and the plasma confinement magnetic field.