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P08 · Observation of Energetic Particle Mode by Using Microwave Reflectometer

T. Tokuzawa¹, S. Yamamoto², K. Kawahata¹, S. Sakakibara¹, K. Toi¹, M. Osakabe¹, and LHD Experimental Group¹

¹National Institute for Fusion Science, Toki 509-5292, Japan
²Osaka University, Suita 565-0871, Japan

Abstract: Two heterodyne reflectometer systems are utilized for the fluctuation measurement in the Large Helical Device (LHD). By using the extraordinary polarized wave, we can measure the corresponding value to the combined fluctuation with the electron density and the magnetic field in the plasma core region even if the radial electron density profile is flat. E-band system has three channels of fixed frequencies of 78, 72, 65 GHz. The system is very convenient to observe magnetohydrodynamics (MHD) phenomena such as energetic particle driven Alfvén eigenmodes, even if the system works as an interferometer mode. The detailed behaviour of the energetic particle mode is studied when low-n MHD burst is occurred. It seems to be caused that the spatial distribution of high energy particle is changed by such a MHD-burst. Also to know the radial distribution of MHD mode, frequency swept R-band reflectometer is applied for the first time. It seems to be successfully detected the energetic particle mode and toroidal Alfvén eigenmode.

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