Validation of equilibrium tools on the COMPASS tokamak

•Three equilibrium codes—EFIT++, FREEBIE and VacTH—have been successfully set up and validated on COMPASS.•FREEBIE can predictively calculate the equilibrium and corresponding poloidal field coil currents.•EFIT++ can reconstruct equilibria generated by FREEBIE from synthetic, optionally noisy diagnostic data.•VacTH is a promising tool for real time plasma shape reconstruction.•Optimized parameters are estimated for EFIT++ and VacTH by a statistical analysis. Various MHD (magnetohydrodynamic) equilibrium tools, some of which being recently developed or considerably updated, are used on the COMPASS tokamak at IPP Prague. MHD equilibrium is a fundamental property of the tokamak plasma, whose knowledge is required for many diagnostics and modelling tools. Proper benchmarking and validation of equilibrium tools is thus key for interpreting and planning tokamak experiments. We present here benchmarks and comparisons to experimental data of the EFIT++ reconstruction code (Appel et al., 2006), the free-boundary equilibrium code FREEBIE (Artaud and Kim, 2012), and a rapid plasma boundary reconstruction code VacTH (Faugeras et al., 2014). We demonstrate that FREEBIE can calculate the equilibrium and corresponding poloidal field (PF) coils currents consistently with EFIT++ reconstructions from experimental data. Both EFIT++ and VacTH can reconstruct equilibria generated by FREEBIE from synthetic, optionally noisy diagnostic data. Hence, VacTH is suitable for real-time control. Optimum reconstruction parameters are estimated.