Excitation and propagation of low frequency wave in a FRC plasma

Abstract

Low frequency f = ⅕ − ⅓fci, (fci: ion gyro frequency in the external field Bw) waves are excited with an antenna which is compatible with a reactor in a plasma with field reversed configuration (FRC). Near and outside the separatrix rs of the FRC plasma, though the applied wave is mainly in compressional mode, azimuthal and radial components are observed in the magnetic field disturbance of the excited wave, which propagate with the dispersion relation consistent with the shear Alfvén wave. These disturbances penetrate deep into the FRC plasma across the surface where the wave frequency exceeds local ion gyro frequency and propagate along magnetic lines of force with sound velocity, which behaviour is consistent with the shear Alfvén wave with finite temperature correction. Axial magnetic disturbance propagates axially and radially from the antenna across the plasma column.