Fusion reactions in a plasma focus operated with³He-D₂and⁴He-D₂gas mixtures

A 3 kJ plasma focus (PF) device was operated with two different gas mixtures: 3 He-D 2 and 4 He-D 2 , both having He/D atomic ratios of 1 : 1. For the 3 He-D 2 mixture, the fusion reactions D( 3 He,p) 4 He and D(d,p) 3 H were measured simultaneously using CR-39 nuclear track detectors located inside a pinhole camera positioned on the forward PF axis. A double-layer arrangement of two 1000 μm thick CR-39 detectors permitted the separate registration of protons from the D( 3 He,p) 4 He and D(d,p) 3 H reactions. For the 4 He-D 2 mixture, the D(d,p) 3 H protons were registered by a single CR-39 layer. Radial track density distributions were obtained for each series of experiments. For the 3 He-D 2 mixture, it was found that D( 3 He,p) 4 He and D(d,p) 3 H fusion yields were of similar magnitude, but the D( 3 He,p) 4 He fusion is concentrated close to the pinch column, whereas the D(d,p) 3 H fusion occurred relatively far from the pinch. The results for D(d,p) 3 H fusion in the 4 He-D 2 mixture enabled an informative comparison to bemade with the corresponding 3 He-D 2 data.