Status of the J-PARC RF ion source

Okoshi, Kiyonori ; Ueno, Akira ; Ikegami, Kiyoshi*; Takagi, Akira*; Asano, Hiroyuki; Oguri, Hidetomo 

In order to satisfy the requirements of the J-PARC second stage, which will produce a 1MW beam, the Cs-free LaB-filament-driven H ion source was replaced to a cesiated RF-driven H ion source (RF ion source) during the summer shutdown period in 2014. By developing and testing the RF ion source on an off-line test-stand for about five years, it successfully and stably produced a peak current of more than 60mA within the acceptance of the following RFQ linac with the required beam duty-factor of more than 1.25% (500s 25Hz). For about one year, the RF ion source has been operated with a peak current of 33mA routinely, which causes low beam loss in the J-PARC operated with a 500kW beam. It has been also operated with a peak current of 55mA for a few weeks in each two months for the J-PARC beam study striving toward the 1MW beam operation. The beam current is controlled within the error of 0.1mA by feed-backing the RF power and the Cs density during the operation. Except for the only one failure of the internal RF-antenna in the beginning of the operation, there was no serious trouble. The RF ion source with the 33mA peak current operation is successfully operated for approximately 1100 hours.