Design and performance analysis of a high field side antenna for plasma position reflectometry control on DTT

Abstract

The Divertor Test Tokamak (DTT) will allow the test and validation, in reactor-like regimes, of control diagnostics relevant to DEMO operation. In DEMO, Plasma Position Reflectometry (PPR) will provide non-magnetic measurements of plasma position and shape, involving the use of several poloidally distributed lines-of-sight (LOS). A multi-LOS PPR is presently under design on DTT to gather more experimental knowledge on the operation of such systems out of the usual equatorial plane LOS. Priority has been given to planning the High-field-side (HFS) reflectometers due to their impact on the design of the first wall and vessel. To cope with the severe space and access constraints imposed to the antenna placement on the inner side of the tokamak vessel, two optimized, small-footprint, bistatic and monostatic hog-horn antenna designs are proposed. To demonstrate the viability of a PPR implementation on DTT's HFS, we present herein 3D full-wave simulations in the DTT single null plasma scenario, laboratory measurements of a 3D-printed bistatic antenna prototype, and a preliminary thermal analysis of the antenna when embedded in the plasma-facing wall structures under standard plasma operation conditions.