Silicon absolute extreme ultraviolet ͑AXUV͒ photodiodes have been employed in a disruption radiometer diagnostic for measurement of radiant power in the DIII-D tokamak with a 170 kHz bandwidth. This is motivated by a need to improve the understanding of radiative processes in tokamak disruptions. The diagnostic described in this article has a single line of sight though the central plasma. Accounting for the photon energy dependence of the AXUV photodiode responsivity is made possible by optical filtering, with the aid of spectra from an extreme ultraviolet survey spectrometer. The appropriate effective responsivity for interpretation of the data is lower than the nominal value typically used for the detector. In the current quench phase of disruptions, it is less than half the nominal value. Comparisons with results from a foil bolometer find good agreement.

Edge localized mode (ELM) effects in the DIII-D pedestal and boundary plasmas were measured with multiple fast diagnostics in matched, lower single-null, ELMing H-mode discharges with the ion B · $B drift either toward or away from the divertor. Data show a strong dependence of the delay in inner vs. outer divertor ELM D a on drift direction, and a weaker drift dependence of the inner vs. outer delay of P rad , in addition to the strong density dependence seen in previous work. Time dependent boundary plasma modeling during an ELM was done with the UEDGE code including a six-species fluid carbon model and the effect of B-field induced particle drifts. The ELM was modeled as an instantaneous, outer midplane peaked, increase of diffusion coefficients from the top of the pedestal to the SOL. The simulations show delays in the inner vs. outer divertor ELM transients that are similar to the measured delays at moderate density.