Antenna coupling and absorption mechanisms in a helicon source operation

Abstract

Summary form only given, as follows. The MAX_EB computer code was used to study and model helicon sources. MAX_EB, a two-dimensional (r,z) simulation code, calculates the electromagnetic wave fields and power absorption in an inhomogeneous cold plasma immersed in a non-uniform magnetic field. A phenomenological collision frequency is used to simulate power dissipation. The current distribution of the launching antenna which provides the full antenna spectra is included in the model. We are in the process of improving the code to include thermal effects. A local k/sub z/ value will be estimated from the calculated 3-D (r,/spl theta/,z) electromagnetic wave fields. This k/sub z/ value will be used to approximate the hot plasma dielectric tensor. Preliminary studies of the power absorption profile that includes the Landau damping term are presented. We will benchmark the modified MAX_EB code with our ANTENA2 code for an axially uniform plasma in a uniform axial magnetic field. 2-D profile on the wave properties and power absorption is investigated. Detailed studies of the wave fields and electron heating profile due to collisional and collisionless wave absorption mechanisms in a nonuniform plasma for the dominant azimuthal mode numbers are presented.