Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6746345 | Fusion Engineering and Design | 2015 | 6 Pages |
Abstract
The ITER electron cyclotron system is designed to inject a 20Â MW RF beam by using twenty-four 170Â GHz/1Â MW gyrotrons. JAEA is currently developing a gyrotron having a high-order mode (TE31,11) to reduce the heat load in the cavity resonator and achieve an output power greater than 1Â MW. The measured radiation profile at the front of the diamond window agreed with the results of the calculation. In order to suppress RF loss in the equatorial and upper port launchers, a high-quality HE11 mode is required at the exit of the matching optics unit (MOU). An HE11 mode purity of 96% was achieved by finely adjusting the two mirrors in the MOU. During the oscillation start-up phase, mode competition with counter-rotating TE29,12 mode was observed on the higher magnetic field side which caused arcing and pressure increase in the gyrotron. To avoid the counter-rotating TE29,12 mode from being excited, a start-up scenario that controls the voltage between the anode and cathode electrodes at the initial phase of operation was introduced, which was able to achieve a stable start-up of TE31,11 mode. A 1.2Â MW output power having a total electric efficiency of 43% was obtained in high-power experiments. In steady-state operation, a 1000Â s oscillation length and output power of 0.51Â MW was achieved.
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Energy Engineering and Power Technology
Authors
Ryosuke Ikeda, Ken Kajiwara, Yasuhisa Oda, Koji Takahashi, Keishi Sakamoto,