Performance assessment of critical waveguide bends for the ITER in-vessel plasma position reflectometry systems

•Critical in-vessel waveguide components of ITER’s PPR diagnostic were investigated.•Simulations of the 90° bend show excellent performance over full range (15–75GHz).•Simulations of the 90° bend compare favorably with laboratory tests up to 43GHz.•Results show that the 90° bend can be further optimized for O-mode only operation.•Performance of the 125° bend is optimized with an hyperbolic secant geometry.