Perfectly matched pulsed 2MHz RF network and CW 30MHz RF matching network for the J-PARC RF-driven H ion source

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

In order to satisfy the J-PARC second stage requirements a cesiated RF-driven H ion source using a internal-antenna developed at the Spallation Neutron Source (SNS) was developed. As similar as the SNS ion source, two matching networks for pulsed high-temperature 2MHz-RF plasma and CW low-temperature 30MHz-RF plasma are used. Each of them is composed of two vacuum variable condensers (VVCs). In order to supply pulsed 60kW - 2MHz-RF power from the power supply (PS) on the ground level, a one-turn isolation transformer using FINEMET cores is installed between the PS and the J-PARC ion source. Up to 46kW of pulsed 2MHz-RF power is successfully input to the plasma stably and with almost no reflected power.