Adaptive-Array electron cyclotron emission diagnostics using data streaming in a software defined radio system

Measurement of the Electron Cyclotron Emission (ECE) spectrum is one of the most popular electron temperature diagnostics in nuclear fusion plasma research. A 2-dimensional ECE imaging systemwas developed with an adaptive-Array approach. Aradio-frequency (RF) heterodyne detection system with Software Defined Radio (SDR) devices and a phased-Array receiver antenna was used to measure the phase and amplitude of the ECE wave. The SDR heterodyne system could continuously measure the phase and amplitude with sufficient accuracy and time resolution while the previous digitizer system could only acquire data at specific times. Robust streaming phase measurements for adaptive-Arrayed continuous ECE diagnostics were demonstrated using Fast Fourier Transform (FFT) analysis with the SDR system. The emission field pattern was reconstructed using adaptive-Array analysis. The reconstructed profileswere discussed using profiles calculated from coherent single-frequency radiation from the phase array antenna.