IPF-FD3D is a finite difference time domain code developed at IGVP that solves Maxwell's equations and the electron equations of motion in a cold plasma. It can simulate the propagation of waves in time dependent magnetised plasmas and arbitrary dielectrics. It can be set up to work in 1, 2, and 3 dimensions.
The advantage of this kind of code is the explicit time stepping of the differential equations, which allows the modelling of arbitrary time-dependent processes and multifrequency simulations. The figure shows a 3D modeling of a moderately oversized TE01-TE02 mode converter. Plotted are the input and output electric field distributions.
The code is used mainly for the investigation of Doppler reflectometry diagnostics, and for calculating the absorption of corrugated surfaces. Simulations of reflectometry spectra are carried out in order to interpret the measurements. The simulations are set up with background density fluctuations obtained from turbulence codes. Reflectometry at fluctuating cutoffs is investigated. The figure shows a microwave beam propagating from the upper right into an ASDEX Upgrade discharge, with dashed density contours and the cutoff in blue.
In our recent paper we find signifikant modifications to the measured wavenumer spectrum by strong turbulent fluctuations: Lechte_et_al-Doppler-reflectometry-simulations-of-k-spectrum_2017.pdf
A movie illustrating the Doppler reflectometry principle is here: Doppler-Reflectometry-Graphical-Demonstration-Movie
We offer PhD topics in reflectometry: reflectometry-PhD-topics-v04.pdf
Carsten LechteDr. rer. nat.
Leader, Microwave Technology