The progress of on-building ECRH system on J-TEXT

As a flexible and controllable auxiliary heating method, electron cyclotron electron heating and current drive has been widely used in various plasma confinement devices and also will be used on J-TEXT. The main parts of the J-TEXT electron cyclotron systems under development are donated by the Culham Science Center, including six 60 GHz/200 kW/5 s (0.5 s) gyrotrons, six magnets and anode power supplies for the gyrotrons, transmission parts, etc. For these systems, the output mode of the gyrotron is TE₀₂ mode and converted to TE₀₁ mode for low loss transmission. Then the HE₁₁ mode for efficient coupling is obtained at the end of the transmission lines by a TE₀₁ - TE₁₁ - HE₁₁ mode conversion sequence. A 100kV/60A pulse step modulation power supply has been developed to feed all the six gyrotrons. The control system based on the Compact Reconfigurable I/O - 9068 platform of National Instruments for monitoring, timing and protection is being designed. Other units such as the cooling loops, a new quasi-optical launcher and a spared auxiliary power supply are on the way. It hopes that four to six EC subsystems can be finally used on the J-TEXT tokamak, and the first one is scheduled to be completed at the end of 2015. (author)