Speaker
Sunao Maebara
(Rokkasho Fusion Research Institute)
Description
For the IFMIF/EVEDA accelerator prototype RFQ linac, the operation frequency of 175MHz was selected to accelerate a large current of 125mA. The driving RF power of 1.28MW by 8 RF input couplers has to be injected into the RFQ cavity for CW operation mode. For each RF input coupler, nominal RF power of 160kW and maximum transmitted RF power of 200kW are required.
For this purpose, an RF input coupler based ona6 1/8 inch co-axial waveguide was designed. The RF coupler has cooling channels into the loop antenna and inner/outer-conductors around the RF window, and the RF window module is replaceable by flanged connection.
RF power tests using a high voltage standing wave on a high-Q load circuit were carried out. This circuit consists of the RF input coupler, a co-axial phase shifter and stub tuner. The RF input coupler and the stub tuner are located in both circuit edge, and these work as a short plate. Therefore, a standing wave due to incident/reflected RF power can be generated when RF power injection into this circuit.
Using this standing wave, equivalent RF power of 200kW-14 sec CW operation was performed after four days of RF aging. No RF contact defects, unnecessary low-Q value and extraordinary outgassing were observed. This article describes RF power tests of RF input coupler using a high voltage standing wave for the IFMIF/EVEDA accelerator prototype RFQ linac.
Co-author
Sunao Maebara
(Rokkasho Fusion Research Institute, JAPAN ATOMIC ENERGY AGENCY, Kitakami, Aomori, Japan)
