X‐Ray Spectra from Dense Plasma Focus Devices

X‐ray spectra with energies up to 350 keV are reported for two paraboloidal plasma focus devices, the Mark I and Mark III device. Low energy x rays with energies between 5.46 and 29.2 keV were measured with Ross filters. Both time resolved and time integrated spectra were obtained. The higher energy x rays from 60 to 350 keV were measured with K‐5 nuclear emulsions. The energies of the individual electrons produced by the photoelectric effect and by Compton scattering in the nuclear emulsion were measured and the x‐ray spectra were deduced. The x‐ray spectra from each device can be represented by the function (dN/dE)E = AE−m. In the Mark I device, A = (0.85 ± 0.28) × 108 ergs (keV)1.5 and m = (2.5 ± 0.8); in the Mark III device, A = (3.8 ± 1.0) × 108 ergs (keV)1.5 and m = (2.5 ± 1.0), where E is the photon energy in kiloelectron volts. Both spectra are similar in shape, but the x‐ray intensity from Mark III, with four times the bank energy, is greater. The x rays appear to be produced by thick target brem...