A 1D cylindrical kinetic wave code for helicon plasma sources

Abstract We describe a 1D plasma kinetic code UFEM, which is specifically designed for the treatment of radiofrequency wave excitation and propagation in cylindrical low temperature plasmas. The code should find extensive application in the design and study of helicon wave driven plasma sources which are increasingly used for industrial plasma processing. The code includes the effects of collisional dissipation and the important parallel electron dynamics, such as Landau damping, that are necessary for the description of wave absorption. It employs a finite element discretization of rf fields in terms of electromagnetic potentials that is suitable for wave calculations in the lower hydrid range of frequencies where helicon waves typically propagate. Finite Larmor radius effects are known to be negligible in industrial plasma sources. These are therefore neglected leading to a considerable simplification of the dielectric tensor; in particular, the complex issue of the equilibrium gradient terms is avoided. The user can choose from a menu of several standard antenna types so that antenna optimizations can be readily performed. Four different variations of cylindrical system geometry can be used. The important issues of complex antenna near-fields and short wavelength modes can be treated fully self-consistently. We also perform a benchmark of the UFEM and ISMENE 5 codes for four different wave conditions over the Alfven to lower hybrid frequency ranges. Finally we conclude with a presentation of code results for the conditions of a typical helicon plasma source driven by a realistic antenna.

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