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

The dense plasma gives an average neutron yield Y = 2 x 108 when it is operated using D2 at an homogeneous pressure p = 1.5 mb in the discharge chamber, in this p-static operation, the frequency of good shots (Y > 107) is f ∼ 50%. In this work the authors show the results on Y and f when PACO is operated in gas-puff way with two different modalities: (1) A gas cloud is injected into the vacuum, from a set of holes distributed in a diameter of the inner electrode near the Pyrex insulator. The gas is introduced from the back of the hollow inner electrode by means of a fast valve. The cloud expands in the interelectrode space, and reaches the extreme of the coaxial cavity in some hundreds of microseconds from the valve aperture instant. In this way of operation the value of Y remains similar to the p-static operation, but the frequency f is improved up to f ∼ 80%. (2) With a relative low value of p in the discharge chamber a jet of high density D2 is injected along the axis from the inner electrode just in the focus zone. The jet is produced with a nozzle designed in order to obtain subsonic velocity, and the gas is injected through the same fast valve. In this jet operation mode the PACO performance was improved, reaching f ∼ 70% and Y ∼ 109