Neutron and high energy deuteron anisotropy investigations in plasma focus device

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.

Breakthrough in 4π ion emission mechanism understanding in plasma focus devices

“…Some applications include radioisotope production67, thin film material processing8, synthesis of nanophase materials910, ion implantation11, lithography12, radiography imaging13 and neutron sources14.…”

“…Some studies have focused on wider-angle ion emission distributions in PFDs71835363738. Measurement of high energy neutrons at an angle of about 180° assumed to be due to energetic ions in the backward direction of the electrode axis36; detection of deuterium accelerated in the backward direction more than 90° in a PFD by using activation of graphite foil7; measurement of deuterium at 0°, 60° and 180° angular positions in the upstream and downstream directions along the z -axis of a PF-1000 device by PM-355 detectors suggesting that a portion of fast ion population are originated from the regions between electrode arrays18; ion images recorded during discharges with a complex structure, usually in the form of a central bunch and an annular stream composed of many micro-beams37; development of a full kinetic model proposed on predicting ion beams in both z directions, albeit with much stronger beams in the forward direction35, and last but not least the observation of a wide-angle x-ray image formation with cathode x-ray shadows in a PFD space39.…”

“…Measurement of high energy neutrons at an angle of about 180° assumed to be due to energetic ions in the backward direction of the electrode axis36; detection of deuterium accelerated in the backward direction more than 90° in a PFD by using activation of graphite foil7; measurement of deuterium at 0°, 60° and 180° angular positions in the upstream and downstream directions along the z -axis of a PF-1000 device by PM-355 detectors suggesting that a portion of fast ion population are originated from the regions between electrode arrays18; ion images recorded during discharges with a complex structure, usually in the form of a central bunch and an annular stream composed of many micro-beams37; development of a full kinetic model proposed on predicting ion beams in both z directions, albeit with much stronger beams in the forward direction35, and last but not least the observation of a wide-angle x-ray image formation with cathode x-ray shadows in a PFD space39. In particular, a recent study on hydrogen ion angular distributions in 19 kJ PFD using CR-39 detectors displayed at 9 discrete angles from −80° to 90° on a circular frame of 11 cm diameter around the anode tip concluded that high current density ion beams are observed even in far off-axis positions and the ions with energies lower than 300 keV are distributed widely over the emission angle of ±80°, while the higher-energy protons (>1 MeV) are confined in the half cone angle of ±30° 38.…”

Correlation Analysis of Intense and High-Energy Deuteron Beam, Pinch Images, and Neutron Yield

“…The NX2 plasma focus device is a high-repetition-rate (up to 16 Hz) medium-energy Mather-type plasma focus device [12]. Energy storage was provided by a 27.6-µF capacitor bank coupled to the plasma focus electrodes through four pseudospark switches.…”

Neutron spectra from beam-target reactions in dense Z-pinches

“…We also note that it is common in the experimental literature to use anisotropy of the neutron yield as a signature of BT neutron production. [17][18][19] Less frequently, isotropy of the neutron yield has been used to infer a TN source. 20 However, in this work, we show that it is possible to get an isotropic neutron yield and spectra from a BT source due to magnetization of the accelerated ions.…”