EC beam tracing in fusion plasmas

• Published in: Fusion engineering and design 2001, Vol.53 (1), p.9-21
• Main Authors: Poli, E., Pereverzev, G.V., Peeters, A.G., Bornatici, M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Beam tracing; Collimated wave beams; Computational methods; Controled nuclear fusion plants; EC heating; Electromagnetic wave diffraction; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Geometrical optics; Installations for energy generation and conversion: thermal and electrical energy; Light absorption; Optical collimators; Ordinary differential equations; Plasmas; Wavefronts
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/S0920-3796(00)00471-3

The aim of the beam tracing technique is to include in the description of short-wavelength electromagnetic wave beams the effects of diffraction, which are neglected by the standard ray tracing method, but can play a significant role in focused or collimated wave beams. Beam tracing is, from a physical point of view, very close to other similar approaches, such as the parabolic equation and the complex eikonal description. In the beam tracing method, however, the problem is greatly simplified, since the full wave equation is reduced to a set of ordinary differential equations that describe the behaviour of the beam axis, the width of the beam and the curvature of the wave front. The propagation of an electromagnetic wave beam in a simplified (slab) geometry can be studied analytically. These calculations allow investigation of situations in which the role of diffraction becomes significant, and clarification of the basic mathematical features of the formalism. In order to solve the problem for realistic plasma geometries and arbitrary launching conditions for the wave beam, a numerical approach is necessary. A new code is presented, in which the beam tracing equations are integrated. Examples of absorption and current drive profiles are shown for RTO/RC ITER.