A table-top plasma focus and its neutron emission

Summary form only given. A 2.2 KJ, compact plasma focus device put on a small table was developed for a movable neutron source. The electrode geometry represents an accelerator of Mather type. Both anode (16 mm diam) and cathode are 85 mm in length and machined from oxygen-free copper. Two cathodes of different configuration were used. The first one (50 mm diam) is made of a cylinder and the second one (56 mm diam) made of 8 rods (14 mm in diam). An alumina insulator, 30 mm in length, was chosen. The DPF is powered by a 14 uF capacitor bank; a field distortion spark gap serves as switch. With the DPF in operation at 18 kV, a current peak of 230 kA occurs at 1.6 us, corresponding to a circuit inductance about 67 nH. The working gas is deuterium which was filled into the discharge chamber through a filter of an electrically heated palladium tube after the chamber was evacuated to a pre-fill vacuum of 10/sup -5/ Torr. Neutron output as measured with a silver activation counter was recorded side-on, i.e., perpendicular to the pinch axis, as a function of deuterium gas pressure for the cylinder cathode and the rods cathode. The neutron yield is strongly correlated with the amplitude of the well-known "dip" in di/dt curve.