Characterization of the AURORA FXR Photon Radiation Field for SREMP Studies

Radiation transport and electromagnetic field calculations were performed in order to characterize the field sources for source region EMP experiments performed in the AURORA flash x-ray facility. Electron-photon transport calculations were performed to obtain the energy-angular dependent photon output of the AURORA bremsstrahlung converters. Four spatial representations of the AURORA photon source were investigated: plane wave, point source at the AURORA hot spot, 4 point sources at the converter centers, and 4 sources uniformly distributed over the converter surfaces. Photon transport and electron transport calculations were performed to obtain the photo-Compton current and air ionization within the HDL Blue Cylinder EMP test chamber. Field calculations were performed for air-filled and evacuated test chamber conditions. Based on examination of the fields sensitivities to the photon source representation, we conclude that the 4-point or 4-distributed spatial source representation with our calculated energy-angular distribution is satisfactory for EMP calculations. The plane wave and hot spot representations we find to be unsatisfactory.