Pavel Kubes, Daniel Klir, Jozef Kravarik, and Karel Rezac
Abstract: Neutrons from deuteron–deuteron fusion reactions were used for the study of pinch dynamics in a modified small plasma-focus device at a current peak of 200 kA. In front of the inner electrode (anode), an antielectrode was placed. Neutron yield reached 105 − 107 per shot. The time-resolved neutron signals were registered with two scintillation detectors positioned end-on and side-on at the same distance of 150 cm from the interelectrode gap. They enabled the comparison of difference in energies and estimation of directions of fast deuterons producing neutrons. The XUV frames imaged the pinch configuration at the moment of X-ray and neutron emission and differed in shots with high and low neutron yields. Interferograms enabled the evaluation of distribution of plasma density. The presence of the antianode decreased the neutron yield and influenced the distribution of the plasma density in front of the anode.
Pavel Kubes and his colleagues at the Warsaw, Poland Center for Dense Plasma Studies, have studied a modification of the DPF, using an “anti-anode” another electrode placed opposite to the main anode along the device’s axis. Unfortunately, the modification decreased neutron yield. It is important that such negative results be published, as well as positive ones, to prevent other researchers from going down the same routes.