Numerical experiments on the PF1000 plasma focus device operated with nitrogen and oxygen gases

Abstract

The indicative values of reduced Pease–Braginskii (P–B) currents are estimated for a nitrogen and oxygen plasma focus. The values of depletion times indicate that in N2 and O2 with estimated 3–4% of pinch energy radiating away over the duration of the pinch, we may expect some cooling effects leading to small reductions in radius ratio. In other gases with higher atomic number, the pinch duration is much more than the depletion time, so radiative contraction may be anticipated. The Lee model was employed to study the soft X-ray from PF1000 operated with nitrogen and oxygen. We found nitrogen soft X-ray yield in the water window region of 3.13 kJ, with the corresponding efficiency of 0.9% of the stored energy [Formula: see text], while for the oxygen it was found to be [Formula: see text] = 4.9 kJ, with the efficiency of 1.4% [Formula: see text]. The very modest enhancement of compression (radius ratios around 0.1) in the pinches of these two gases gives rise to rather modest pinch energy densities (PEDs) under 109 Jm[Formula: see text]. This is in contrast to Kr or Xe where it had been shown that the radiative collapse leads to radius ratios of 0.007 and 0.003, respectively, with PEDs going to large values considerably exceeding 10[Formula: see text] Jm[Formula: see text].

Effect of atomic number and pressure on plasma pinch properties and characteristic soft x-ray emission in PF1000

“…Therefore, we may conclude that our computed results are justified with those from Z-pinch. By comparing our results of numerical simulation with the research results [4,32], both the characteristics soft x-ray and PED increase with the increase in atomic number (N 2 , O 2 , and Ne) of used gases due to two factors: radius ratio and the effective ion charge while in our study we continue the increase in atomic number (Ar) of gas. We also focus on the effect of induced voltage, absorption correction factor, and ion density on the characteristics soft x-ray as it is found that both Y sxr and PED increase for high atomic number gases (N 2 , O 2 , and Ne) and then sharply reduce for Ar gas because the radius ratio and hence the number of ions inside the pinch of Ar plasma reduces significantly.…”

“…The experimental current trace for different gases in this device is not available. Though this set of model parameters is expected to vary considerably within a wide range of gases, even in a pressure range for a given gas, these are kept fixed throughout our present series of numerical experiments for different gases [4,15,17].…”

“…The study of pinch plasmas as a bright soft x-ray source is well established. Although it is simple to construct [1,2] the dense plasma focus (DPF) emits x-ray emission efficiently when compared with other pinches including the X-pinch [3] and vacuum spark [4]. Applications in the x-ray spectrum range include spectroscopy [5], microscopy and microlithography [6], for pumping lasers [7], crystallography [8], medical and industrial radiography [9], for back-lighter [10], and for engineering micromachining [11].…”

Characteristics of Ion Beam for Various Gases in a Spherical Plasma Focus Device

“…The Lee code is configured to conduct the numerical experiments using the following standard parameters of this device [34] These model parameters have been obtained by fitting the computed current trace with the measured one at 14.3 Torr D-T in KPU200 SPF [33]- [34]. Though, this set of model parameters is expected to vary slightly within a wide range of gases, even in a pressure range for a given gas [36]- [37] these are kept constant in our present numerical experiments for different gases in the pressure range of 0.1 -19 Torr.…”

Correlation of Pinch Properties with Minimum Pinch Radius in UNU/ICTP PFF for Different Pressure of Argon Gas

“…The radial trajectories and tube voltage, pinch temperature, radiations, and ion density for different pressure were studied numerically including and excluding self-absorption term for argon, krypton, and xenon gases (Akel & Lee, 2013). The soft X-ray yield, pinch energy density (stored capacitor energy injected into the pinch column divided by its volume), and minimum pinch radius were correlated with pressure variation in PF1000 for nitrogen and oxygen gases using Lee code (Akel et al 2017).…”