Impact of MARFE on interferometric electron density measurements in the EAST tokamak

Accurate electron density diagnostics are essential for plasma stability and control in tokamak operations. However, Multifaceted Asymmetric Radiation From the Edge (MARFE) can significantly distort interferometric measurements by introducing strong refractive effects and may cause signal loss, especially under high-density conditions. This study aims to evaluate how MARFE events interfere with electron density measurements, and to identify their spatial signatures and diagnostic consequences in the EAST tokamak. To this end, we present a novel combination of a vertical solid-state source interferometer, a horizontal far-infrared polarimeter-interferometer, and edge imaging with a high-speed charge-coupled device camera. Integrating this diagnostic suite with ray-tracing simulations enables spatially resolved reconstruction of MARFE-induced density profiles and assessment of signal distortion mechanisms. Results show that MARFE structures lead to significant signal distortion in edge channels, whereas central channels maintain better resilience. The estimated MARFE peak density exhibits clear correlation with impurity radiation intensity, supporting the interpretation that impurity-induced radiation cooling drives local density compression.