Paraxial WKB Method Applied to the Lower Hybrid Wave Propagation
Authors: N. Bertelli, O. Maj, E. Poli, R. Harvey, J.C. Wright, P.T. Bonoli, C.K. Phillips, A.P. Simov, E. Valeo and J.R. Wilson
Abstract:
The paraxial WKB (pWKB) approximation, also called beam tracing method, has
been employed in order to study the propagation of lower hybrid (LH) waves in a
tokamak plasma. Analogous to the well-know ray tracing method, this approach
reduces Maxwell's equations to a set of ordinary differential equations, while, in
addition, retains the effects of the finite beam cross-section, and, thus, the effects of
diffraction.
A new code, LHBEAM (Lower Hybrid BEAM tracing), is presented, which solves
the pWKB equations in tokamak geometry for arbitrary launching conditions and
for analytic and experimental plasma equilibria. In addition, LHBEAM includes linear
electron Landau damping for the evaluation of the absorbed power density and the
reconstruction of the wave electric field in both the physical and Fourier space. Illustrative
LHBEAM calculations are presented along with a comparison with the ray tracing code GENRAY and the full wave solver TORIC-LH.
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Submitted to: Physics of Plasmas (June 2012)
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Download PPPL-4780 (pdf KB pp)
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