Development of a Heavy Ion Beam Probe Synthetic Diagnostic for Wendelstein 7-X*

The optimized magnetic field geometry of Wendelstein 7-X (W7-X) reduces neoclassical transport, with turbulence becoming the governing mechanism for confinement. Challenges characterizing anomalous transport due to turbulence highlight the need for direct measurements of particle transport, instead of relying on particle balance estimates. A Heavy Ion Beam Probe (HIBP) diagnostic can simultaneously measure the plasma electrostatic potential and density fluctuations and thus contribute important information to the characterization of anomalous particle transport and motivates its installation on W7-X.

A synthetic diagnostic provides the forward model necessary to predict the diagnostic’s response to different operating and plasma conditions. Additional inputs to the forward model are the fluctuations and equilibrium electrostatic potential obtained from the global electromagnetic gyrokinetic code GENE-3D. With this, measurements under different plasma scenarios in W7-X are predicted and the sensitivity, resolution, and limitations of the diagnostic can be estimated. Furthermore, upon installation of the HIBP on W7-X, a synthetic diagnostic becomes an invaluable tool for the interpretation of experimental data and its analysis. The developed model and predicted capabilities obtained are presented in this work.