Development of water choke model for high-voltage deck of ITER neutral beam

Tsuchida, Kazuki; Watanabe, Kazuhiro; Yamanaka, Haruhiko; Takemoto, Jumpei; Inoue, Takashi; Tanaka, Shigeru*; Yamashita, Yasuo*

In ITER Neutral Beam (NB) injection system, the negative ion source and the accelerator should be cooled to generate high energy and high power beam for the prolonged operation. Those devices will be settled at high electric potential of -1 MV and an water choke is needed in the cooling water line to insulate the high voltage. The water choke for ITER should meet the following specifications; high water pressure (2 MPa) and high leak current (several ten mA) due to the reduction of resistivity in hot water (65 C), etc. So, we developed a ceramic insulation tube for the water choke of ITER NB system and it's performance was confirmed by mechanical and withstand voltage tests. From the test results, it was confirmed the developed ceramic tube has sufficient performance (110 kV/tube) as a part of ITER water choke. The anti-corrosion and anti-dissolution of the sealing materials in the ceramic tube was also confirmed under the high leak current condition.