As a first step toward the development of a compact and portable, quasi-continuous pulsed neutron source, we have demonstrated a 'fast miniature plasma focus (PF) device' as a compact nuclear fusion apparatus. The system operates with deuterium gas and produces an average neutron yield (Y 90 • ) of (1 ± 0.27) × 10 4 neutrons/shot at ∼70 kA peak discharge current. In the range of 1.5-4 mbar, a distinct and sharp dip in the current derivative signal indicates a strong pinching action with subsequent emission of hard x-rays followed by a neutron pulse. The yield and the time history of the neutrons were measured by both active and passive detection techniques (such as a 3 He proportional counter, NE102A plastic scintillator and CR-39 SSNTDs). The overall dimensions of the apparatus, which includes a capacitor bank, sparkgap switch and the focus chamber, are 0.2 m × 0.2 m × 0.5 m and the total mass of the system is ∼25 kg. The scope of this paper is to evaluate/demonstrate the potential of such a fast miniature PF device as a compact and portable fusion apparatus producing neutrons while operating at relatively low energy.

No abstract

The anisotropies of neutron and high energy deuteron emissions from the NX2 plasma focus device ͓M. V. Roshan et al., Phys. Lett. A 373, 851 ͑2009͔͒ are studied. The nuclear activation of graphite targets is used to measure the fluences of high energy deuterons in the axial and radial directions. Two bismuth germanate scintillation detectors connected to multichannel analyzer systems are used for the detection of 511 keV gamma rays resulting from positron annihilation in the two targets. In addition, fast neutron activation detectors are employed to measure the axial and radial fluences of fusion neutrons. These detection systems are calibrated using the simulation code MCNPX ͓L. S. Waters et al., AIP Conf. Proc. 896, 81 ͑2007͔͒. Two distinct regimes of neutron and deuteron anisotropies are observed for the NX2 device. For deuterium gas pressures below 10 mbar, the neutron anisotropy increases with increasing pressure, while the overall neutron yield remains low. For gas pressures of 10-14 mbar, the neutron anisotropy is essentially constant, while, with increasing pressure, the neutron yield rises rapidly and the deuteron anisotropy falls.

No abstract