Characteristics of low level RF system for DTL1 beam commissioning of J-PARC linac

Kobayashi, Tetsuya; Suzuki, Hiroyuki*; Anami, Shozo*; Yamaguchi, Seiya*; Kawamura, Masato*; Fukui, Yuji*; Kadokura, Eiichi*; Kamikubota, Norihiko*; Takagi, Makoto*; Yoshida, Susumu*; Kawase, Masato*

The beam study of the low-energy front of J-PARC linac has been in progress in the KEK site. Last year, DTL1 (the first tank of three DTL's) was installed in addition to RFQ and the Medium Energy Beam Transport line, and the beam commissioning up to 20MeV has been performed successfully. In this paper, the low level RF (LLRF) System for this beam test is summarized and the performance of the RF feed back control system and monitor system of the phase and amplitude of the accelerating fields (324 MHz) is presented. It was found that the feed back system for Bunchers is also necessary to stabilize and to compensate for the beam induced fields.