Bragg resonance picture of one-dimensional fluctuation reflectometry beyond the Born approximation (abstract)

By using HELM1D, a numerical, one-dimensional Helmholtz equation solver, we have studied the scattering phase shifts of S-polarized O modes in fluctuation reflectometry both within and beyond the Born approximation. Comparisons are made between these numerical results and analytical expressions obtained through the use of the Born approximation. As the fluctuation amplitude increases, various peaks of the phase response evolve with distinct growth rates. This leads to steepening and distortion of the scattering phase shift due to a single wave-number fluctuation. The simultaneous coexistence of large amplitude fluctuations with nearby wave numbers complicates the task of resolving the response at each wave number