Generation of polarized shear Alfvén waves by a rotating magnetic field source

Experiments are performed in the Large Plasma Device at the University of California, Los Angeles to study the propagation of field-aligned, polarized kinetic shear Alfvén waves radiated from a rotating magnetic field source created via a novel phased orthogonal loop antenna. Both right and left hand circular polarizations are generated at a wide range of frequencies from 0.21≤ω/Ωci<0.93. Propagation parallel to the background magnetic field near the Alfvén velocity is observed along with a small parallel wave magnetic field component implying a shear mode. The peak-to-peak magnitude of the wave magnetic field, 33 cm away from the antenna, is on the order of 0.8% of the background field and drops off in the far field. The full width at half maximum of the wave energy changes little over a distance of 2.5 parallel wavelengths while the exponential decrease in wave energy as a function of distance can be attributed to collisional damping. Evidence of electron heating and ionization is observed during the pulse.