Synchronized operation of new, spectrally filtered X-point fast camera with multiple fast cameras to study filamentary transport in MAST-U

A spectrally filtered fast visible camera viewing the lower X-point is installed on the Mega Ampere Spherical Tokamak - Upgrade (MAST-U) to study the filamentary plasma transport in standard and advanced divertor configurations. The X-point camera has a complementary metal–oxide–semiconductor sensor with high light sensitivity, capable of 12-bit, 16 500 fps operation at full frame resolution of 1024 × 1024 pixels. It is coupled to the front lens via a coherent fiber optic bundle and a pair of relay lenses. Spatial camera calibration is performed to map the real space onto 2D pixel coordinates of the camera image, which enables identification and tracking of plasma filaments. For the first time, the X-point camera is operated in synchronization with other fast cameras, one viewing the main chamber plasma tangentially and the other in the Super-X divertor chamber, at a 100 kHz frame rate with a time lag <1 μs. This technique enables us to compare the filamentary transport in the Super-X divertor chamber in MAST-U with the midplane and X-point regions along the same flux tube.