Assessment of the measurement performance of the in-vessel system of gap 6 of the ITER Plasma Position Reflectometer using a Finite-Difference Time-Domain Maxwell full-wave code
Résumé
We conducted a first assessment of the measurement performance of the in-vessel components at Gap 6 of the ITER Plasma Position Reflectometry (PPR) with the aid of a synthetic Ordinary Mode (O-mode) broadband Frequency-Modulated Continuous-Wave (FMCW) reflectometer implemented with REFMUL, a 2D Finite-Difference Time-Domain full-wave Maxwell code. These simulations take into account the system location within the vacuum vessel as well as its access to the plasma. The plasma case considered is a baseline scenario from Fusion for Energy. We concluded that for the analyzed scenario: (i) the plasma curvature and non-equatorial position of the antenna have neglectable impact on the measurements; (ii) the cavity-like space surrounding the antenna can cause deflection and splitting of the probing beam and (iii) multi-reflections on the blanket wall cause a substantial error preventing the system from operating within the required error margin