Effects of the neutral gas density distribution in a DPF neutron yield

Summary form only given. The dense plasma focus PACO (2 kJ, 31 kV, 250 kA, Mather-type gun) gives an average neutron yield Y=2/spl times/10/sup 8/ when it is operated using D/sub 2/ at an homogeneous pressure p=1.5 mb in the discharge chamber. In this p-static operation, the frequency of good shots (Y>10/sup 7/) is f/spl ap/50%. In this work we show the results on Y and f when PACO is operated in gas-puff way with two different modalities: a) A gas cloud is injected into the vacuum, from a set of holes distributed in a diameter of the inner electrode near of the Pyrex insulator. The pattern of the high density cloud front and its dynamics, is determined using a very fast density probe, and the profile of this front is verified with shadow photographs illuminating the cloud with an exploding wire device. b) With a relative low value of p in the discharge chamber (p=0.5 mb) a jet of high density D/sub 2/ is injected along the axis from the inner electrode just in the focus zone. The cone pattern and its dynamics were experimentally determined through the same diagnostic methods used in the case a).