First step towards a synthetic diagnostic for cross-polarization scattering measurements of magnetic turbulence on DIII-D*

A cross-polarization scattering (CPS) diagnostic measures localized magnetic fluctuations in fusion plasmas. CPS on DIII-D utilizes the probe beam of a Doppler backscattering (DBS) diagnostic combined with a cross-view CPS receiver system, which allows simultaneous measurement of magnetic and density fluctuations with good spatial resolution and wavenumber coverage. A synthetic CPS diagnostic is essential to interpret data and perform detailed validation tests of non-linear turbulence simulations due to the complex plasma propagation of the probe and receive beams. This work reports the first step towards a synthetic CPS diagnostic utilizing GENRAY, a 3-D ray tracing code, to simulate propagation of the DBS probe and CPS scattered rays within the plasma. The factors that determine measured wavenumbers and spatial locations are discussed and initial comparison with experimental data is presented. Future development steps for the synthetic diagnostic include 2 and 3D full wave simulations.