  Plasma turbulence, and edge density fluctuations in particular, can under
certain conditions broaden the cross-section of injected microwave beams
significantly. This can be a severe problem for applications relying on
well-localized deposition of the microwave power, like the control of MHD
instabilities. Here we investigate this broadening mechanism as a function of
fluctuation level, background density and propagation length in a
fusion-relevant scenario using two numerical codes, the full-wave code IPF-FDMC
and the novel wave kinetic equation solver WKBeam. The latter treats the
effects of fluctuations using a statistical approach, based on an iterative
solution of the scattering problem (Born approximation). The full-wave
simulations are used to benchmark this approach. The Born approximation is
shown to be valid over a large parameter range, including ITER-relevant
scenarios.
