High definition imaging in the Mega Ampere Spherical Tokamak
An absolutely calibrated, visible imaging diagnostic has been deployed on the MAST spherical tokamak. Two sets of three colour channels are defined using a combination of stacked multi-cavity interference filters, colour-glass filter and a colour-pixel sensor. The system is compact with a single viewing pupil which facilitates unambiguous comparisons of measurements in 2D. System has a 12-bit dynamic range, 5-10ms integration time (100-200Hz frame rate), a wide field of view that encompasses 1.6m at the plasma equator and 2.5mm projected pixel size. Spectral characteristics are robust across the field of view and designed such that the edge and plasma interior charge-exchange impurity line-emission are spatially-separated for both MAST neutral particle beams. Second set of colour channels measure beam emission and two colours of plasma bremsstrahlung.