A bremsstrahlung diagnostic has been deployed on the Mega Ampere Spherical Tokamak ( MAST ) , with matrix viewing of the full plasma cross section in a narrow region of the continuum free of spectral lines. An uncooled CCD detector is used to provide 100 Hz 128 3 128 matrix viewing of the plasma emissivity which is spectrally selected using an interference filter of only , 0.5 nm bandwidth. The apparently conflicting demands of a large field of view for the plasma and the small solid angle for narrow spectral bandwidth is accommodated in a compact lens, filter, and detector arrangement. Using measured electron temperature and density profiles the Z eff profile evolution is determined.
