Numerical experiments on plasma focus neutron yield versus pressure compared with laboratory experiments

Abstract

Published literature shows that the neutron yield of the plasma focus has been modeled in two papers using a thermonuclear mechanism. However, it is more widely held that plasma focus neutrons are produced mainly by nonthermalized mechanisms such as beam-target. Moreover these papers use several parameters which are adjusted for each machine until the computed neutron yield Y n data agree with measured Y n data. For this paper numerical experiments are carried out, using the Lee model code, incorporating a beam-target mechanism to compute the Y n versus pressure data of plasma focus devices PF-400 J and FN-II. The Lee model code is first configured for each of these two machines by fitting the computed current waveform against a measured current waveform. Thereafter all results are computed without adjusting any parameters. Computed results of Y n versus pressure for each device are compared with the measured Y n versus pressure data. The comparison shows degrees of agreement between the laboratory measurements and the computed results.

Imaging of Plasma Focus Fusion by Proton Coded Aperture Technique

“…The dimension of the CR-39 detectors used are 3.0 9 3.0 cm 2 for 0°and 4.5 9 3.0 cm 2 for 45°, while L M for the mask was 0.8 cm (square), so the FOVs in the source plane were 6.8 9 6.8 cm 2 for 0°and 4.5 9 2.4 cm 2 for 45°. Based on numerical simulations of PF dynamics, the expected dimensions of the PF pinch column are about 10 mm length and 2 mm diameter [11], which are easily within the fully coded FOV. The resolution of a CAI camera is effectively the magnified pixel size in the source plane.…”

Numerical Experiments Providing New Insights into Plasma Focus Fusion Devices

“…Temperature and number densities are computed during this phase using shock-jump equations. A communication delay between shock front and current sheath due to the finite small disturbance speed [6,26,39] is crucially implemented in this phase. The model parameters, radial phase mass swept-up and current factors f mr and f cr are incorporated in all three radial phases.…”

Comparison of Plasma Dynamics in Plasma Focus Devices PF1000 and PF400

“…The experimental data ofcurrent curve at 28 kV and 6.6 Torrfor the PF400 is taken from the work by Lee et al [2009]. As usual we first fit the current wave form, for finding the model parameters fm, fc, fmr and fcras discussed in the case of PF1000.…”

“…As usual we first fit the current wave form, for finding the model parameters fm, fc, fmr and fcras discussed in the case of PF1000. To obtain the reasonably good fit the following bank and tube parameters (L 0 , C 0 and z 0 refitted and r 0 fitted) are used: The computed current waveform fitted to the measured current waveform [Lee et al 2009] is shown in Figure 2. The fit is good up to the end of the radial pinch phase.…”