Coded aperture imaging of fusion source in a plasma focus operated with pure D2 and a D2-Kr gas admixture

The coded aperture imaging (CAI) technique has been used to investigate the spatial distribution of DD fusion in a 1.6 kJ plasma focus (PF) device operated in, alternatively, pure deuterium or deuterium-krypton admixture. The coded mask pattern is based on a singer cyclic difference set with 25% open fraction and positioned close to 90° to the plasma focus axis, with CR-39 detectors used to register tracks of protons from the D(d, p)T reaction. Comparing the coded aperture imagingprotonimages for pure D₂ and D₂-Kr admixture operation reveals clear differences in size, density, and shape between the fusion sources for these two cases.