Comprehensive Study on Soft X-Ray Emission from Admixtures of Nitrogen and Neon Gases in the APF Plasma Focus Device

The present work is an investigation on the effect of working gas composition as well as applied voltage and operating pressure on the behavior of SXR emitted from the APF device. Three volumetric ratios(90:10), (75:25), and (50:50) of nitrogen:neon (N₂:Ne) admixture were used with operating conditions at applied voltages of 11, 12, and 13 kV and operating pressures of 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 torr. Using (N₂:Ne) gas mixture ratios of (90:10) and (75:25) and at applied voltage of 11 kV, the optimum pressure for maximum intensity of SXR was 3.5 torr. However, for the percentage of (50:50), it shifts to higher pressure of 4 torr. At higher applied voltages of 12 and 13 kV, the optimum pressures shift to higher values, 4 torr for both volumetric ratios (90:10) and (75:25), and 4.5 torr for the ratio of (50:50). It was found that the intensity of SXR increases with the increase of neon (Ne) percentage in the admixture of (N₂:Ne) and applied voltage. The highest intensity was for the volumetric ratio of (50:50) operating at the voltage of 13 kV. Our results illustrated that mixing neon (Ne) with nitrogen (N₂) as the working gas in the PF is a power source of SXR emission.     

Neon Soft X-Ray Yield Optimization from PF-SY1 Plasma Focus Device

Based on the consideration of that for operation of the plasma focus in neon, a focus pinch compression temperature of 200–500 eV (2.3 × 10⁶–5 × 10⁶ K) is suitable for good yield of neon soft X-rays (SXR), numerical experiments have been investigated on the plasma focus device PF-SY1 using the latest version Lee model code. The Lee model code is firstly applied to characterize the PF-SY1 Plasma Focus. Keeping the bank parameters and operational voltage unchanged but systematically changing other parameters, numerical experiments were performed finding the optimum Y _sxr was 0.026 J. Thus we expect to increase the neon Y _sxr of PF-SY1 from its present typical operation; without changing the capacitor bank and the electrode configuration merely by changing the operating pressure. The Lee model code was also used to run numerical experiments on PF-SY1 with neon gas for optimizing soft X-ray yield with reducing L ₀, varying z ₀ and ‘a’. From these numerical experiments we expect to increase the neon Y _sxr of PF-SY1 with reducing L ₀, from the present 0.026 J at L ₀ = 1600 nH to maximum value of near 26 J at an achievable L ₀ = 10 nH.     

Numerical Experiments on Neon Soft X-Ray Optimization of AECS-PF2 Plasma Focus Device

Numerical experiments have been investigated on modified AECS-PF2 with neon filling gas using the latest version of Lee model. The model was applied to characterize the 2.8 kJ plasma focus AECS-PF2, finding a neon soft X-ray yield (Y_sxr) of 0.04 J in its typical operation. By numerical experiments the optimum combination of pressure of 0.57 Torr, anode length of 9 cm and anode radius of 1.57 cm was found. The optimum Y_sxr found also to be 0.87 J. Thus we expect to increase the neon Y_sxr of AECS-PF2 22-fold from its present typical operation; without changing the capacitor bank, merely by changing the electrode configuration. The Lee model code was also used to run numerical experiments on AECS-PF2 with neon gas for optimizing soft X-ray yield with reducing L₀, varying z₀ and ‘a’. From these numerical experiments we expect to increase the neon Y_sxr of AECS-PF2 with reducing L₀, from the present 0.04 J at L₀ = 280 nH to maximum value of near 21 J at an achievable L₀ = 15 nH at the pressure 2.8 Torr.     

Comprehensive Study of Neon HXR and SXR Emitted from APF Plasma Focus Device

Experimental results related to HXR and SXR properties of Neon plasma on the APF plasma focus device is presented. The experiments were carried on over a wide range of neon pressure and at voltages 11, 12 and 13 kV using plastic scintillator (NE102A) coupled with high gain PMT and six filtered photo PIN diodes. For the charging voltages of 11–13 kV with 2.17–3.04 kJ stored energy, the optimum operating pressure in neon is found to be in the range of 3.5–5 torr and the highest HXR emission was observed in the pressure of 5 torr at the voltage 13 kV and the maximum average HXR production is (9.84 ± 0.59) ×10^–7 volt sec. The behavior of SXR intensities were registered by different filters and it was found out that Al-Mylar 6 μm and Cu 10 μm has the highest and lowest amount of X-ray transmission.     

Study of the Soft and Hard X-Ray Emitted by APF Plasma Focus Device in Different Pressures

In this paper, an investigation on the X-rays emitted in different pressures by APF plasma focus devices using filtered PIN-diodes and fast plastic scintillation detector is reported. The highest X-ray emission was observed in the pressure of 1.6 torr and the behavior of X-ray intensities registered by different filters versus applied pressure were seemed to be similar. The X-ray angular distribution was bimodal, peaked approximately at ±18°. The intensity of X-rays decreased abruptly along the central axis of the device where the cylindrical plasma pinch was formed.     

Numerical Analysis of Amirkabir Plasma Focus (APF) Device for Neon and Argon Gases

In this paper the experimental results in different working conditions in Amirkabir Plasma Focus (APF) Device have been compared with the numerical results of a two-dimensional simulation code based on Lee’s model. The experiments were done with pure Neon and Argon as operating gases over a wide range of working conditions (gas pressures and discharge voltages). It is observed that by a proper choice for values of the efficiency factors, comparison between numerical and experimental results shows a good agreement.     

Investigation of Nitrogen HXR with Neon Admixture on the APF Plasma Focus

An investigation on the HXR emitted from APF plasma focus device operated with different volumetric ratios of nitrogen-neon (N₂:Ne) admixture working gas at different voltage-pressure limits is presented. The optimum pressures obtained at the applied voltages of 12, and 13 kV were 3.5 torr for percentage of (50:50) of (N₂:Ne) admixture and 3 torr for percentages of (75:25) and (90:10) in admixture and also for pure N₂, while at the voltage of 11 kV, the optimum pressures were 3 torr for percentage of (50:50) and 2.5 torr for percentages of (75:25), (90:10), and pure N₂. At each applied voltages of 11, 12, and 13 kV, with increasing percentage of N₂ in the (N₂:Ne) admixture, the intensity of HXR was found to increase where the low intensity was for percentage of (50:50) of (N₂:Ne) and the higher intensity was for pure N₂. The results illustrate that the voltage and the composition of working gas are effective parameters in the HXR emission from a plasma focus device.     

Experimental Study of Hard X-ray Emission with Different Anode Tips in APF Plasma Focus Device

To investigate the effect of different anode tips on the hard X-ray (HXR) emission from APF plasma focus device (16 kV, 36 μf, and 115 nH) we considered two shapes of anode tips, i.e., flat or conic, with Cu, Al and W anode tip materials. The highest HXR intensity was observed with conic W anode insert and the lowest with flat Al anode insert. In comparison with the hollow anode tube the HXR signals obtained from flat and especially conic W inserts nearly tending to have the same intensity along the axis of the device. Therefore the shape and the material of the anode tip has significant effect on the production of HXR emissions. This study show that the employment of a convenient shape of anode tip results to more isotropic emission of HXR.     

Anisotropic Investigation of Hard X-ray Emission with Flat Anode Tips in APF Plasma Focus Device

In this paper behavior of hard X-ray (HXR) anisotropy and its intensity along the anode bar from APF plasma focus facility (16 kV, 36 μf, and 115 nH) with different anode tip materials investigated experimentally. Magnetic probe signals registered to choose only discharges with high degree of current sheath symmetry. The signals obtained by scintillation detectors by a special arrangement at each angular position show that the employment of higher Z anode insert materials not only increase the intensity of HXR signal, but also result to high degree isotropic emission of HXR. The side on emitted intensity along the anode bar has been studied by moving the detector in the direction of central electrode axis. The results confirm the importance of anode tip material on HXR signal intensity.     

Numerical Experiments on IR-MPF-100 Plasma Focus Operated in Neon and Deuterium Gases

In this paper, using the current fitting method, the Lee model parameters are computed for the IR-MPF-100 plasma focus (maximum energy ～115 kJ) operated in the neon and deuterium gases and the results are presented in the different operational conditions. The values of f_c, f_cr and f_mr were obtained 0.43, 0.55 and 0.05 respectively for the neon gas in all values of pressure and voltage. f_m varies as a function of pressure and voltage. f_m varies from 0.03 to 0.04 for 23.3 kJ of energy and it is almost constant equal to 0.024 for 10.2 kJ of energy. In the case of deuterium gas, f_c and f_cr are found 0.3 and 0.4 respectively. In this case, \({\text{f}}_{\text{m}}\) varies between 0.028 and 0.1 and f_mr varies between 0.05 and 0.20. It is noted that in the case of deuterium gas, f_m and f_mr decrease with the pressure increasing approximately and in the case of neon gas f_m increases with pressure increasing. So we calculate neutron yield and soft X-ray yield using the Lee model code for the different operational conditions.     

Soft X-Ray Emission Optimization Study with Nitrogen Gas in a 1.2 kJ Plasma Focus

Measurement of soft x-ray emission from a low-energy plasma focus operated with nitrogen within the pressure range of 0.1–1.0 mbar is presented. The x-rays are detected by using an assembly of Quantrad Si PIN-diodes with differential filtering and with a multipinhole camera. In the 1.0–1.3 keV and 1.0–1.5 keV windows, the x-ray yield in 4 geometry is 1.03 J and 14.0 J, respectively, at a filling pressure of 0.25 mbar and the corresponding efficiencies are 0.04% and 1.22%. The total x-ray emission in 4 geometry is estimated at 21.8 J, which corresponds to the system efficiency of about 1.9%. The soft x-ray emission is found dominantly as a result of electron beam activity on the anode tip, which is confirmed by the images recorded by a pinhole camera.     

Soft X-Ray Emission in the Water Window Region with Nitrogen Filling in a Low Energy Plasma Focus

For operation of the plasma focus in nitrogen, a focus pinch compression temperature range of 74–173 eV (0.86 × 10⁶–2 × 10⁶ K) is found to be suitable for good yield of nitrogen soft X-rays in the water window region. Using this temperature window, numerical experiments using five phase Lee model have been investigated on UNU/ICTP PFF and APF plasma focus devices with nitrogen filling gas. The Lee model was applied to characterize and optimize these two plasma focus devices. The optimum nitrogen soft X-ray yield was found to be Y_sxr = 2.73 J, with the corresponding efficiency of 0.13 % for UNU/ICTP PFF device, while for APF device it was Y_sxr = 4.84 J, with the corresponding efficiency of 0.19 % without changing the capacitor bank, merely by changing the electrode configuration and operating pressure. The Lee model code was also used to run numerical experiments for optimizing soft X-ray yield with reducing L₀, varying z₀ and ‘a’. From these numerical experiments we expect to increase the nitrogen soft X-ray yield of low energy plasma focus devices to maximum value of near 8 J, with the corresponding efficiency of 0.4 %, at an achievable L₀ = 10 nH.     

Soft X-ray Imaging using a Neon Filled Plasma Focus X-ray Source

A 3 kJ Mather-type UNU/ICTP plasma focus device with neon filling is used, for the first time, as a soft X-ray source for imaging of thin biological samples including insects. A charge-coupled-device (CCD) based pinhole projection system, placed in a differentially pumped chamber, is used for radiography using neon soft X-rays. The image brightness, contrast and resolution have been optimized by varying soft X-ray yield, pinhole size, camera chamber length and X-ray filters. The system can simply be modified for table-top soft X-ray microscopy of thin biological samples.     

A Study on Plasma Polymerization of Acrylic Acid Using APF Plasma Focus Device

The most conventional way for polymerization of acrylic acid on different substrates is using RF devices and introducing of other devices is under way. In this work we have a new study on formation of polymer Acrylic Acid using APF plasma focus device. The formation of plasma polymer acrylic acid is discussed using results obtained from attenuated total reflectance infrared spectroscopy (ATR). The results show that after 15 shots, nitrogen pulses performed polymerization on the specimens and the main peaks of ATR spectra assured poly acrylic acid formation on SBR substrate.     

Computational Study of Emitted Spectra from the Neon Plasma Focus

The expected emission spectra (full, Bremsstrahlung, recombination, and line) of neon focussed plasma have been studied for different conditions. Expected neon plasma spectra at certain electron temperature range have been plotted. The suitable electron temperatures ranges for neon plasma soft X-ray emission and extreme ultraviolet emission have been investigated. The X-ray ratio curves for various electron temperatures with probable electron and ion densities of the neon plasma produced have been computed with the assumption of non-local thermodynamic equilibrium model for the distribution of the ionic species. These ratio curves could be used for electron temperatures deduction of neon plasma focus.     

Model Parameters Versus Gas Pressure in Two Different Plasma Focus Devices Operated in Argon and Neon

For the plasma focus device AECS PF-2 operated in Ar and INTI PF in Ne, model parameters of mass and current in the axial phase of plasma focus were found by matching the measured and calculated current waveforms over a range of pressures. The results show a value of f_m = 0.05 ± 0.01 over 0.2–1.2 Torr in Ar; and f_m = 0.04 ± 0.01 over 0.7–4.1 Torr in Neon. The value of f_c = 0.7 was fitted for all cases. Combining these results with those published for several other small machines it would appear that, where measured current waveforms are not available for example in designing new machines, a good compromise would be to take a guideline value of f_m = 0.05 and f_c = 0.7 for both Argon and Neon.     

Study of Dense Nitrogen Plasma Irradiation of Aluminum Targets by APF Plasma Focus Device

The nitridation of Al surfaces is obtained by irradiating nitrogen ions from APF device. The Vickers Micro-Hardness values are improved approximately three times for the nitrided samples comparing to the non-nitrided ones. The X-ray diffraction analysis is carried out in order to explore the phase changes in the near surface structure of the metals. The Nuclear Reaction Analysis shows the depth of the nitride composed on the metal surfaces clearly and quantitatively. The results of Scanning Electron Microscopy indicate changes in surface morphology which are the emergence of a smooth and uniform film scattered on the surface of the nitrided specimens.     

Ion Beam Emission in a Low Energy Plasma Focus Device

The characteristics of the Ar ion beam generated in a low energy plasma focus device were investigated. A Mather-type PF device filled with argon gas driven by an 11 μF single capacitor bank was used. A Faraday cup, operating in the bias ion collector mode, is used to estimate the energy spectrum and ion flux along the PF axis. The results of the experiments show the dependence of the energy spectrum on the gas pressure and the anode shape.     

Investigation of the Neutron Angular Distribution and Neutron Yield on the APF Plasma Focus Device

This paper presents an experimental study of neutron yield as well as neutron angular distribution on the APF plasma focus device. The system operates with pure deuterium gas in varying the filling pressure and working voltages of 11.5 and 13.5 kV. The maximum average of neutron yield is (2.88 ± 0.29 × 10⁸) neutrons per shot at the pressure of 7 torr. The neutron angular distribution is measured with housing an array of seven silver activation Geiger-Muller counters at the angles of 0°, ±30°, ±60°, and ±90° in a distance of 90 cm from the anode tip. The results of neutron angular distribution suggest that the neutron production mechanism may be predominantly beam target model.     

Studies of the Hard X-ray Emission from the Filippov Type Plasma Focus Device, Dena

This article is about the characteristics of the hard X-ray (HXR) emission from the Filippov type plasma focus (PF) device, Dena. The article begins with a brief presentation of Dena, and the mechanism of the HXR production in PF devices. Then using the differential absorption spectrometry, the energy resolved spectrum of the HXR emission from a 37 kJ discharge in Dena, is estimated. The energy flux density and the energy fluence of this emission have also been calculated to be 1.9 kJ cm⁻² s⁻¹ and 9.4 × 10⁻⁵ J cm⁻². In the end, after presentation of radiography of sheep bones and calf ribs, the medical application of the PF devices has been discussed.