Neutron and high energy deuteron anisotropy investigations inplasma focus device

摘要

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 (2009)] are studied. The nuclear activation of graphitetargets 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 usedfor the detection of 511 keV gamma rays resulting from positron annihilation in the two targets. Inaddition, fast neutron activation detectors are employed to measure the axial and radial fluences offusion neutrons. These detection systems are calibrated using the simulation code MCNPX [L. S.Waters et al., AIP Conf. Proc. 896, 81 (2007)]. Two distinct regimes of neutron and deuteronanisotropies are observed for the NX2 device. For deuterium gas pressures below 10 mbar, theneutron 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, withincreasing pressure, the neutron yield rises rapidly and the deuteron anisotropy falls