TEXT upgrade far‐infrared interferometer system

A high‐resolution 2‐D interferometer is being developed to measure electron density profiles in the TEXT‐upgrade tokamak. Excellent port access allows both horizontal and vertical chords, which will be used to resolve plasma asymmetries. Close channel spacing is employed to give good spatial resolution. In addition, the system can be operated in an imaging mode to resolve the steep gradients expected in H‐mode operation.