Abstract
A FAst DIrectional Switch (FADIS) of 2-frequency (2-ƒ ) gyrotron system for the JT-60SA project is being developed under collaboration between Japan Atomic Energy Agency (JAEA) and Kyushu University. At first, the frequency drift and dip in the gyrotron operation were measured to consider which kind of FADIS is preferred for application in the Electron Cyclotron Heating and Current Drive (ECHCD) system for the JT- 60SA. Various types of the FADIS have been considered. A square corrugated waveguide diplexer system with double resonant rings was considered as one of the most attractive FADIS systems for stable high-power and long-pulse operations in the 2-ƒ JT-60SA ECHCD system.
Highlights
Local current generation by Electron Cyclotron Current Drive (ECCD) has been used to suppress Neoclassical Tearing Mode (NTM) activities in many tokamaks such as the JT-60U [1,2,3], the ASDEX-U [4], the DIII-D [5]
A collaboration task on the FAst DIrectional Switch (FADIS) for the 2- f gyrotron system has begun between Japan Atomic Energy Agency and Kyushu University for the effective NTM suppression in various experimental scenarios on the JT-60SA
Various types of the FADIS have been considered for the 2- f application for the JT-60SA Electron Cyclotron Heating and Current Drive (ECHCD) system
Summary
Local current generation by Electron Cyclotron Current Drive (ECCD) has been used to suppress Neoclassical Tearing Mode (NTM) activities in many tokamaks such as the JT-60U [1,2,3], the ASDEX-U [4], the DIII-D [5]. Synchronous switched injection for mode rotation of the NTM magnetic island has been proposed as a more effective suppression method relative to the continuous injection. The synchronous injection experiments were conducted with different phasing between the mode rotation and the modulated ECCD injection in the JT-60U [3]. Perturbed magnetic field components resulting from the NTM activity began to be decreased by the synchronous injection in in-phase experiments, while they were not changed so much and were increased by ECCD injection being out of phase by 90 and 180 degrees for the mode rotation, respectively. The synchronous in-phase injection was effective for the NTM suppression in experiments at ASDEX-U [4]. Various types of the FADIS have been considered under the measured frequency dip and controllability in the JT-60SA ECHCD system.
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