Study of the spatial measurement of electron density in the EAST discharge using a multichannel terahertz solid-source interferometer

Abstract A vertical single-channel 0.65 THz solid-source interferometer (SSI) has been established at Experimental Advanced Superconducting Tokamak (EAST) for real-time electron density measurements and feedback. A line array detection scheme was proposed and successfully deployed on EAST to enhance the spatial resolution of the SSI system. The scheme utilizes an AlGaN/GaN line array high electron mobility transistor detector, and three channels of line-integrated electron density signals were measured. A representative density measurement was conducted with an intermediate frequency of 850 kHz in a discharge with a current ( I p ) of 400 kA and electron cyclotron resonance heating power ( P ECRH ) of 1.1 MW on EAST. Additionally, the detection of density perturbations by the SSI system during plasma discharges demonstrates its capability to study small-scale spatial magnetohydrodynamic phenomena. Further optical refinements and the development of advanced data processing algorithms are anticipated to enhance the measurement accuracy and overall performance of the line array detection scheme.