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.     

Energy and Angular Distributions of High-Energy Nitrogen Ion of Plasma Focus Device SBUMTPF1 by Aluminum Filters Coated on Polycarbonate Nuclear Track Detector

The main objective of this study is to determine energy distribution and angular distribution of nitrogen ions produced in plasma focus device SBUMTPF1 measured with polycarbonate nuclear track detector. To achieve this goal, the detectors were covered by different thicknesses of aluminum filters, using physical vapor deposition method and by coated films the anisotropic distribution of nitrogen ions was investigated. For determination of nitrogen ion energy distribution, the detectors were settled in the distance of 21.5 cm and in 0° angle to the end of anode and for determination of angular distribution of ions, 1,200 nm aluminum coated detectors in 10 cm distance and at angles of 0°, 15°, 30°, 45° and 60° with respect to the anode were used. For better ion detection, a pinhole of 200 μ was used for energy distribution measurement and a pinhole of 500 μ was used for angular distribution measurement. In all experiments electrical discharges were done in the voltage of 23 ± 0.5 kV and nitrogen with the pressure of 0.5 mbar was used as working gas. By using SRIM code, the ranges of nitrogen ions were measured in aluminum. SBUMTPF1 angular distribution curve show a peak at a 30° angle against the anode axis. Besides, the suitable thickness range of aluminum filter for data registration was from 1,240 to 2,620 nm.     

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.     

Role of Ion Beam Irradiation and Annealing Efect on the Deposition of AlON Nanolayers by Using Plasma Focus Device

AlON nanolayers are synthesized on Al substrate by the irradiation of energetic nitrogen ions using plasma focusing. Samples are exposed to multiple(5, 10, 15, 20 and 25) focus shots. Ion energy and ion number density range from 80 keV to 1.4 MeV and 5.6×1019m-3 to 1.3×1019m-3, respectively. Moreover, the efect of continuous annealing(473 K and 523 K) on an AlN surface layer synthesized with 25 focus shots is also examined. The main features of the X-ray difraction(XRD) patterns with increasing focus shots are:(i) variation in the crystallinity of AlN along(111),(200) and(311) planes,(ii) increasing average crystallite size of AlN(111) plane, and(iii) stress relaxation observed in AlN(111) and (200) planes. The crystallinity of AlN surface layer is comparatively better at 473 K annealing temperature. A broadened difraction peak related to an aluminium oxide phase showing weak crystallinity is observed for 15 focus shots while non-bounded oxides are present in all other deposited layers. Raman and Fourier transform infrared spectroscopy(FTIR) analysis confirm the presence of AlN and Al2O3 for the surface layer annealed at 473 K temperature. Raman analysis shows that the overlapping of AlN and Al2O3 results in the development of residual stresses. Scanning electron microscope(SEM) results demonstrate that the formation of rounded grains(range from 20 nm to 200 nm) and variations in their microstructures features depend on the increasing number of focus shots. Decomposition of larger clusters into smaller ones is observed.     

Role of Ion Beam Irradiation and Annealing Effect on the Deposition of AlON Nanolayers by Using Plasma Focus Device

AlON nanolayers are synthesized on Al substrate by the irradiation of energetic nitrogen ions using plasma focusing. Samples are exposed to multiple （5, 10, 15, 20 and 25） focus shots. Ion energy and ion number density range from 80 keV to 1.4 MeV and 5.6×10^19 m^- 3 to 1.3×10^19 m ^-3, respectively. Moreover, the effect of continuous annealing （473 K and 523 K） on an AlN surface layer synthesized with 25 focus shots is also examined. The main features of the X-ray diffraction （XRD） patterns with increasing focus shots are： （i） variation in the crystallinity of AlN along （111）, （200） and （311） planes, （ii） increasing average crystallite size of AlN （111） plane, and （iii） stress relaxation observed in AlN （111） and （200） planes. The crystallinity of AlN surface layer is comparatively better at 473 K annealing temperature. A broadened diffraction peak related to an aluminium oxide phase showing weak crystallinity is observed for 15 focus shots while non-bounded oxides are present in all other deposited layers. Raman and Fourier transform infrared spectroscopy （FTIR） analysis confirm the presence of AlN and Al203 for the surface layer annealed at 473 K temperature. Raman analysis shows that the overlapping of AlN and Al2Oa results in the development of residual stresses. Scanning electron microscope （SEM） results demonstrate that the formation of rounded grains （range from 20 nm to 200 nm） and variations in their microstructures features depend on the increasing number of focus shots. Decomposition of larger clusters into smaller ones is observed.     

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.     

High Energetic Deuteron Ion Irradiation of Al Samples by Dense Plasma Focus Device

In this paper energetic ion beams of a 90 kJ filippov type plasma focus were utilized to irradiation aluminum samples. The working gases were pure D₂, and D₂+Kr2%. The phenomena of melting, micro cracks, evaporation, and sputtering of the surface layer have been noticeable on the samples. Surface smoothing was remarkable when a heavy rare element added to D₂. Adding Kr to the D₂ filling gas lead to collapsing bubbles and greater surface damage. Micro hardness of surface layer tends to decrease particularly in the central region of the sample where destruction is more intense. The decrease in micro hardness for D₂+2%Kr is more than that compared to deuteron ion treated sample.     

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.     

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.     

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.     

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.     

Preparation of Titanium Carbide Thin Film Using Plasma Focus Device

In this work, we report titanium carbide (TiC) formation on the stainless steel—304 substrates by using a low energy (2 kJ) Mather-type plasma focus (PF) device. The argon–acetylene admixture (in 3:1 ratio) was used as the filling gas at a pressure of 1 torr. The thin films were deposited with different number of focus deposition shots (5, 15 and 25 shots), at 0° angular position with respect to the anode axis and at constant distance from the anode tip (10 cm). Deposited thin films have been investigated for their structure by X-Ray diffractometry (XRD) and surface morphology by scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. The average size of crystallites (from XRD), crystalline growth of structures (from SEM), and size of grains and surface roughness (from AFM) were investigated, which increase by increasing the number of focus deposition shots.     

Numerical Study of Radiation Emission from the Argon Plasma Focus

Ion populations and emitted spectrum of argon plasma have been calculated using the POPULATE and SPECTRA codes of the RATION suite at different conditions (electron temperatures, electron densities, ion densities, plasma size) for LTE and NLTE models. Expected argon plasma spectra at certain electron temperature range have been plotted. The suitable electron temperatures ranges for argon plasma soft X-ray (3–4 keV) emission and EUV (60–200 eV) emission have been investigated. POPULATE and SPECTRA codes have been presented as a good assisted tools for plasma focus diagnostics.     

Increase of Diagnostic Mirror Lifetime Using TiN Coated Stainless Steel by Using a Plasma Focus Device

Plasma-surface interaction experiments on TiN coated stainless steel 316L (S.S.316L) using a plasma focus (PF) device have been performed in an attempt to investigate whether we can use the hardness property of TiN against erosion to increase the lifetime of the mirrors used in plasma diagnostics equipment. Firstly, two similar S.S.316L samples were chosen for this purpose. One of the samples was coated with TiN by using a PF device, while the other was kept intact as a reference for investigating the effect of TiN coating. Then, in order to study the coating effects, these samples were exposed to 200 shots of hydrogen plasma with a total duration of 7 s in a tokamak. Before and after exposure, samples were analyzed by using atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and a spectrophotometer. It was found that the uncoated sample was severely damaged, its reflection dropped significantly, and it developed some cracks and lines, while no significant change was observed on the surface characteristic of the coated sample. Moreover the weight loss of the uncoated sample was higher in comparison to the coated one. Therefore the results of this experiment showed that the coating of S.S.316L by TiN using a PF device is a useful method to strengthen it against plasma erosion and with further optimization it could possibly be used in preparing plasma diagnostics mirrors.     

Using Mather-Type Plasma Focus Device for Fabrication of Tungsten Thin Films

Tungsten (W) thin films were deposited on stainless steel–304 substrates using a low energy (2?kJ) plasma focus device. The samples were synthesized at various distances with respect to anode tip (7, 10 and 13?cm) and using same number of focus deposition shots (25 shots). X-ray diffraction (XRD), energy dispersive X-ray atomic force microscopy (AFM) and micro hardness were used to investigate the prepared samples. XRD analysis revealed that the degree of crystallinity of deposited thin films decrease with increasing the distance from the anode tip. AFM results showed that size of the grains on the surface of the films and the surface roughness of deposited samples constantly increase with the increasing of the axial position. Moreover, the hardness measurements revealed that the highest mechanical hardness is obtained when the film is deposited at 7?cm axial position.     

Properties of Ion Beams Generated by Nitrogen Plasma Focus

Numerical experiments have been systematically carried out using the modified Lee model code on various plasma focus devices operated with nitrogen gas. The ion beam properties (ion beam energy, ion beam flux, ion beam fluence, beam ion number, ion beam current, power flow density, and damage factor) of the plasma focus have been studied versus gas pressure for each plasma focus device. The results show that, for these studied plasma focus devices, the mean ion energies decrease with increasing gas pressure, while the beam ion number increases with higher pressure. The fluence, flux, ion current, power flow density and damage factor have maximum values at the optimum pressure. It is shown that, the maximum power flow densities range from 10¹² to 10¹⁴ W m^?2 and the damage factor values reach almost 10⁹–10¹¹ W m^?2 s^0.5. The obtained results provide much needed benchmark reference values and scaling trends for ion beams of a plasma focus operated in nitrogen gas. These results could be used as an indicator for ion properties emitted from nitrogen plasma focus for various applications including material processing.     

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.     

Porous Structure Formation on Silicon Surface Treated by Plasma Focus Device

Pores formation has been observed on silicon surface, induced by plasma focus treatment. The scanning electron microscope observation shows the presence of different pores sizes which scale from micro to nano dimensions. A spacial dependency of pores distribution according to pore sizes is revealed. This distribution is reproducible. The relative nano/micro pores formation is dependent of the experimental conditions (distance from anode and number of shots). The dynamic of pores formation and reason of pores distribution is discussed suggesting the implication of liquid-phase process. The ablated copper from the anode is deposited in noticeable amount on the silicon surface. The lateral distribution and diffusion of copper are investigated using Rutherford Backscattering spectroscopy technique.     

Measurements and Simulations of Neutron Emission Versus Deuterium Filling Pressure in Plasma Focus Device PF-24

A series of experiments were carried out using the middle energy (dense) plasma focus device PF-24 with deuterium as a working gas under pressure in a range between 2 and 5 mbar for 17 kV of charging voltage. The relationship between these operating deuterium pressures in reference to the total neutron yield (Y_n) was estimated. The 5-phase Lee code was used to simulate the measured discharge current and neutron yield (Y_n) using a phenomenological beam-target neutron generating mechanism, which was incorporated in the model. Comparison of the Y_n versus pressure using fitted model parameters was made at each point of pressure. The good agreement between measured and computed Y_n values was achieved for discharges with lower neutron emission. The measured Y_n (below 2.6?×?10⁹ n/discharge—the median value) has been reproducible by the model for 73% of simulated discharges, while above the median value its prediction were incorrect. The kinetic plasma parameters which were measured and computed using the Lee code for different pressures are: the time to a current sheath collapse (t_c), the average axial current sheath velocity (v_z) and the so called velocity factor (RF). Good agreement was found in the whole range of deuterium pressures between the computed and measured results for these kinematic quantities. Presented findings in this work suggest that the character of neutron emission is more complex than it would seem from classical interpretation of neutron production based on a beam-target model.