Speaker
Koji Takahashi
(Department of ITER Project)
Description
The new mirror angle detector for ITER EC launchers, applying a rotary capacitor , a RF feeder, RF circuits and several hundreds MHz RF has been developed. The rotary electrode is attached to the rotation axis of the mirror and the stationary electrode is connected to a RF feeder. The reflected RF wave at the rotary capacitor comes back to the feeder and phase of the reflected RF wave changes depending up on capacitance due to the overlap condition between the two electrodes. The phase change tells us the rotation angle of the mirror. It has been difficult to cool the stationary electrode that must be electrically isolated. Then, application of a co-axial choke stub to the support of the stationary electrode has been utilized since it acts as the electrical isolator. As a result, cooling water can be supplied to the stationary electrode through the center conductor of the choke stub. To solve this issue, a co-axial choke stub tuned at designated RF frequency is applied for for the support of the stationary electrode since it acts as a notch filter to electrically isolate it.
The angle monitor was designed as the radius of the rotary and stationary electrodes, the electrodes’ gap, the stub length and RF frequency were 50mm, 42mm, 2m, 78mm and 900MHz, respectively to verify the applicability to the EC launchers. Then, the mock-up were fabricated and tested. It was obtained that phase difference of the reflected RF wave at the rotation angle change of 14º was 26º, which was well agreed with the design value of 25.7º. It is concluded that the new mirror angle detector is applicable to the rotatable mirror of the EC launchers.
Co-authors
Ganji Abe
(Department of ITER Project, Japan Atomic Energy Agency, Ibaraki, Japan)
Koji Takahashi
(Department of ITER Project, Japan Atomic Energy Agency, Ibaraki, Japan)
Mark Henderson
(ITER Organization, Route de Vinon-sur-Verdon 13067 St. Paul-lez-Durance, France)
Masami Isozaki
(Department of ITER Project, Japan Atomic Energy Agency, Ibaraki, Japan)
Noriyuki Kobayashi
(Department of ITER Project, Japan Atomic Energy Agency, Ibaraki, Japan)
Ryosuke Ikeda
(Department of ITER Project, Japan Atomic Energy Agency, Ibaraki, Japan)
Shinichi Moriyama
(Department of ITER Project, Japan Atomic Energy Agency, Ibaraki, Japan)
Takayauki Kobayashi
(Department of ITER Project, Japan Atomic Energy Agency, Ibaraki, Japan)
Toshimichi Omori
(ITER Organization, Route de Vinon-sur-Verdon 13067 St. Paul-lez-Durance, France)
Yasushi Oda
(Department of ITER Project, Japan Atomic Energy Agency, Ibaraki, Japan)
