Antenna coupling and absorption mechanisms in a helicon source operation

Summary form only given. The ANTENAII computer code, a modified version of the ANTENA code written by McVey, is used to study and model helicon sources. A drifting beam with a small Maxwellian spread characterizing the fast electrons (E/sub e-beam/=30 eV and a width of T/sub e-beam/=3 eV) along with the bulk Maxwellian electron distribution (T/sub e-bulk/=3 eV), comparable to what has been observed experimentally has been added to the code to examine their influence on helicon wave power absorption. We have studied the effects of electron cyclotron damping on power absorption that can occur at low magnetic fields (B/spl ap/1-50 G). The contribution of the off-diagonal hot plasma dielectric tensor terms and that of the transit-time damping to the power dissipated is also examined. We examine different helicon antenna structures and describe the relative processes of wave absorption by collisional, Landau, transit-time and cyclotron damping for a wide range of parameters. Preliminary studies of plasma transport as well as radial plasma uniformity in helicon sources are presented with the aid of the interface of our ANTENAII code with the 2-D fluid transport model, INDUCT95, developed by Vittelo et al. (1995).