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.     

Experimental Study of Current Discharge Behavior and Hard X-ray Anisotropy by APF Plasma Focus Device

Amirkabir (APF) is a new Mather-type plasma focus device (16 kV, 36 μf, and 115 nH). In this work we present some experimental results as variation of discharge current signal respect to applied voltage at the optimum pressure, focusing time of plasma versus gas pressure, and variations of current discharge with different insulator sleeve dimensions. As we prospected optimum pressure tending to increase as we tried to higher voltage levels. The time taken by the current sheath to lift-off the insulator surface and therefore quality of pinched plasma depends on the length of the insulator sleeve. The results show that the insulator diameter can influence on pinch quality. Behavior of hard X-ray (HXR) signals with the pressure and also anisotropy of HXR investigated by the use of two scintillation detectors. The distribution of HXR intensity shows a large anisotropy with a maximum intensity between 22.5° and 45° and also between −22.5° and −67.5°.     

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.     

Characterization of the Soft X-Ray Emission from the APF Plasma Focus Device Operated in Neon

Experimental results related to soft X-ray (SXR) properties of Neon plasma on the APF plasma focus device is presented. The experiments were carried on over wide range of neon pressure and at voltages 11, 12 and 13 kV six filtered photo PIN diodes and pin-hole camera. 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. The behavior of SXR intensities was registered by different filters and found out that Al-Mylar 6 μm and Cu 10 μm has the highest and lowest amount of X-ray transmission, respectively.     

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.     

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.     

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.     

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.     

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.     

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.     

Correlation of Neutron and X-ray Emission from Plasma Focus with Pre-ionization

The effect of pre-ionization caused by depleted uranium (₉₂U²³⁸) on the correlation of neutron and X-ray emission from 1.8 kJ plasma focus is investigated by employing photomultiplier tubes (XP2020) coupled with fast (50 × 50) mm² cylindrical plastic scintillators (NE102A) along with GM tube and Quantrad Si PIN diodes with a pair of appropriate filters. It is found that neutron and Cu–K_α emission along with total X-ray yield are significantly increases with pre-ionization as compared to those without pre-ionization. Moreover, pre-ionization improves the shot to shot reproducibility of the system and broadens the operating pressure regime both for neutron and X-ray emission.     

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.     

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.     

Dependence of Hard X-ray Emissions with the Charging Pressure in a Small Plasma Focus

The dependence with the filling pressure of the hard X-ray emission of a 250 J Plasma-Focus device is presented. The study was performed on the range of Hydrogen pressures between 5 and 23 mbar. It was found that the pressure dependence of the hard X-ray intensity presents a maximum at 16.4 mbar. A threshold in the voltage drop on the pinch was observed for the X-ray emission, which agrees with the Dreicer theory for electrons runaway.     

An Optimized Design of Anode Shape Based on Artificial Neural Network for Achieving Highest X-ray Yield in Plasma Focus Device

In this paper, an optimized design of anode shape in order to achieve highest X-ray yield in a plasma focus device filled with nitrogen gas based on artificial neural networks (ANNs) is presented. Multi-layer perceptron neural network structure with the back-propagation algorithm is used for the training of the proposed model. The model has achieved good agreement with the training data and has yielded satisfactory generalization. This shows that the ANN model is an accurate and reliable approach to predict the highest X-ray yield in plasma focus devices.     

Effect of Quartz and Pyrex Insulators Length on Hard-X ray Signals in APF Plasma Focus Device

This paper, presents the variation of hard X-ray (HXR) intensity in the APF plasma focus device for different insulator sleeves. For Pyrex and Quartz insulators, the lengths of 40 and 50 mm seems optimal to yield maximum HXR intensity, respectively. Also using the Pyrex insulator leads to production of higher HXR intensity than the Quartz insulator. The results illustrate that the length and the material of the insulator has a considerable effect on the HXR intensity.     

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.     

X-ray Emission from Plasma Focus: Envisioned by Various Competitive Detectors

A study of X-ray emission from a Mather-type plasma focus device by simultaneously employing various X-ray detectors like silicon pin diode, photoconducting detectors (PCDs)—CVD-diamond and gallium arsenide (GaAs), plastic scintillator coupled with photomultiplier tube with and with out optical fiber is presented. The pin diode and PCDs are masked with 10 μm thick cobalt filter. The device is energized by 9 μF capacitor bank charged at 18 kV (1.45 kJ), giving a peak discharge current of about 175 kA, with hydrogen as the filling gas. The optical fiber coupling is found to be beneficial in minimizing the electromagnetic noise generated during the system operation.     

Soft X-ray Emission Optimization Studies with Krypton and Xenon Gases in Plasma Focus Using Lee Model

The X-ray emission properties of krypton and xenon plasmas are numerically investigated using corona plasma equilibrium model. Numerical experiments have been investigated on various low energy plasma focus devices with Kr and Xe filling gases using Lee model. The Lee model was applied to characterize and to find the optimum combination of soft X-ray yields (Y_sxr) for krypton (~4 Å) and xenon (~3 Å) plasma focus. These combinations give Y_sxr = 0.018 J for krypton, and Y_sxr = 0.5 J for xenon. Scaling laws on Kr and Xe soft X-ray yields, in terms of storage energies E₀, peak discharge current I_peak and focus pinch current I_pinch were found over the range from 2.8 to 900 kJ. Soft X-ray yields scaling laws in terms of storage energies were found to be as $ {\text{Y}}_{{{\text{sxr}},{\text{Kr}}}} = 0.0003 \times {\text{E}}_{0}^{1.43} $ Y sxr , Kr = 0.0003 × E 0 1.43 and $ {\text{Y}}_{{{\text{sxr}},{\text{Xe}}}} = 0.0064 \times {\text{E}}_{0}^{1.41} $ Y sxr , Xe = 0.0064 × E 0 1.41 for Kr and Xe, respectively, (E₀ in kJ and Y_sxr in J) with the scaling showing gradual deterioration as E₀ rises over the range. The maximum soft X-ray yields are found to be about 0.5 and 27 J from krypton and xenon, respectively, for storage energy of 900 kJ. The optimum efficiencies for soft X-ray yields (0.0002 % for Kr) and (0.0047 % for Xe) are with capacitor bank energies of 67.5 and 225 kJ, respectively.     

Practical Optimization of AECS PF-2 Plasma Focus Device for Argon Soft X-ray Operation

For operation of the plasma focus in argon, a focus pinch compression temperature range of 1.4–5 keV (16.3 × 10⁶–58.14 × 10⁶ K) is found to be suitable for good yield of argon soft X-rays (SXR) Ysxr. This is based on reported temperature measurements of argon plasmas working at regime for X-ray output. Using this temperature window, numerical experiments have been investigated on AECS PF-2 plasma focus device with argon filling gas. The model was applied to characterize the 2.8 kJ plasma focus AECS PF-2. The optimum Ysxr was found to be 0.0035 J. Thus, we expect to increase the argon Ysxr of AECS PF-2, 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 on AECS PF-2 with argon gas for optimizing soft X-ray yield with reducing L₀, varying z₀ and ‘a’. From these numerical experiments we expect to increase the argon Ysxr of AECS PF-2 with reducing L₀, from the present computed 0.0035 J at L₀ = 270 nH to maximum value of near 0.082 J, with the corresponding efficiency is about 0.03%, at an achievable L₀ = 10 nH.