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(EX/P4-18) Excitation and Propagation of Low Frequency Waves in a FRC Plasma

S. Okada1), K. Yamanaka1), S. Yamamoto1), T. Masumoto1), K. Kitano1), T. Asai1), F. Kodera1), M. Inomoto1), S. Yoshimura1), M. Okubo1), S. Sugimoto1), S. Ohi1), S. Goto1)
1) Plasma Physics Labo., Graduate School of Engineering, Osaka University, Suita-city, Japan

Abstract.  Plasma with field reversed configuration (FRC) has extremely high beta value - it consists only of poloidal field and the magnetic field strength changes from that of the external, solenoidal confining field to zero at the magnetic axis. To this FRC plasma, low frequency (55-100 kHz, or 1/5-1/3 ion gyro frequency in the external field) ringing magnetic field which decayed with e-folding time of 30 microsec is applied by an antenna from outside the plasma. Though the main component of the applied field is in the axial direction and the azimuthal component is smaller than other components, the main component of the excited wave magnetic field in the plasma is azimuthal ( b$\scriptstyle \theta$). Axial phase velocity vz and the dispersion relation of b$\scriptstyle \theta$ disturbance near and outside the separatrix is close to that of the Shear Alfvén wave. While, inside the separatrix, vz is close to the sound velocity. Plasma heating by this wave is anticipated if the electric power fed to the antenna is increased, if the number of the antenna is increased or if continuouse wave source is employed.

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IAEA 2003