Two-dimensional interferometric imaging of moving plasma disturbances in the ZT-40M reversed-field pinch, using time-delayed correlation techniques

An eight-chord interferometer array, together with a single-chord interferometer separated toroidally by 90°, shows propagating global plasma density disturbances in the final 1 ms prior to discharge termination in ZT-40M. A time-delayed correlation technique applied to the nine-chord data allows reconstruction of the shape of the propagating disturbance and discriminates against competing random density fluctuations.