Fundamental heating with stellarator wave modes

• Published in: Physics of plasmas 1998-02, Vol.5 (2), p.486-498
• Main Authors: Svidzinski, V. A., Swanson, D. G.
• Format: Article
• Language: English
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/1.872731

A perturbation method is developed to find the structure of Alfvén wave modes in a cylindrical waveguide filled with a cold, collisional, uniform plasma with a vacuum layer between the plasma and a conducting wall when the magnetic field is a superposition of a uniform and an inhomogeneous l=2 field created by helical windings. The influence of the helical field on the wave mode structure is treated as a perturbation. It is shown that the m=−1 azimuthal component of a modified m=+1 fast Alfvén wave is left-hand polarized in the central part of the plasma. This implies a coupling between the m=+1 fast (right-hand polarized) wave and m=−1 slow (left-hand polarized) waves due to the inhomogeneity of the l=2 fields. The coupling efficiency is examined for different plasma parameters. Results demonstrate that efficient coupling between the modes occurs for appropriate plasma parameters in this model, indicating that efficient plasma heating at the fundamental ion cyclotron frequency is possible in stellarators.