Development of a Concept of Reflectometric Diagnostics for the ITER Tokamak for Plasma Probing from the High-Magnetic-Field Side

Abstract

The capabilities of the reflectometric diagnostics in the ITER facility during plasma probing from the high-magnetic-field side are investigated. This technique allows measurements of the density profile and the plasma turbulence-rotation velocity at the lower extraordinary wave from a plasma with a critical density to the center of the plasma column. The system also allows one to probe the plasma column at the ordinary wave. It is proposed to use a combined mirror–horn antenna system. Under conditions where there is limited space for placing horns, this results in a significant (up to 20 dB) increase in the signal, compared to the system of two horns considered earlier. The results of calculations on optimizing the elements of the waveguide transmission line using a two-dimensional full-wave code are presented. The possibility of employing the Doppler effect to study plasma rotation by using antennas for controlling the shape of the plasma column while performing reflectometry at the lower extraordinary wave is considered. This effect is estimated theoretically in the actual ITER plasma configuration.