Shear Alfven wave radiation from a source with small transverse scale length

Shear Alfven waves are studied in the kinetic and inertial regimes. The waves are launched from an antenna which is on the order of the electron collisionless skin-depth, delta=c/omega(pe), in size. The experiment is performed in the LArge Plasma Device, LAPD [W. Gekelman , Rev. Sci. Instrum. 62, 2875 (1991)] at the University of California, Los Angeles, using a new antenna design that modulates parallel plasma electron current. The plasma is 100 skin-depths in diameter and 3.6 Alfven wavelengths long. The results include the calculation of the wave currents based on measurements of the wave magnetic field. Differences in the perpendicular phase velocity of the wave in the kinetic regime as compared to the inertial regime are also reported. Results generally compare favorably with predictions of a theory which includes collisional damping and kinetic electron dynamics with fluid ions. (C) 2000 American Institute of Physics. [S1070-664X(00)04610-3].