Effect of Low-Pressure Nitrogen DC Plasma Treatment on the Surface Properties of Biaxially Oriented Polypropylene, Poly (Methyl Methacrylate) and Polyvinyl Chloride Films

In this study, commercial biaxially oriented polypropylene (BOPP), polyvinyl chloride (PVC) and poly (methyl methacrylate) (PMMA) films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemical changes that appeared on the surface of the samples were investigated using Fourier transform infrared (FT-IR) spectroscopy and attenuated total reflectance Fourier transform infrared (ATR- FTIR) spectroscopy after treatment for 2 min, 4 min and 6 min in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy (AFM) and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times.     

Flame Retardant Properties of Plasma Pretreated/Metallic Salt Loaded Cotton Fabric Before and After Direct Dyeing

In this research work, cotton fabrics were pretreated with low temperature plasma (LTP) and then inoculated in various metallic salts and flame retardancy of cotton fabric was investigated. More polar functional groups were present on the substrate surface after LTP pretreatment. Titanium dioxide (TiO₂), zinc sulfate (ZnSO₄), lead (II) acetate [Pb(C₂H₃O₂)₂], aluminium sulfate [Al₂(SO₄)₃] and silver nitrate (AgNo₃) were used as metallic salts. The flame retardancy of the samples was characterized by limiting oxygen index (LOI) and char yield. Good flame retardant activity for Al₂(SO₄)₃ and AgNo₃ treated fabrics were achieved, however, the effect of TiO₂ and ZnSO₄ on flame retardany of cotton fabrics was moderate. It was concluded that, nitrogen plasma pretreatment, improve the flame retardant properties of cotton samples. The plasma treated and Aluminium sulfate loaded cotton fabric sample has a LOI value of 23.3. It shows that, nitrogen plasma pretreatment has synergistic effect on metallic salts for improving the flame retardant properties of cotton samples. In this research work, the dyeability of samples after loading with metallic salts was investigated. Also effect of dyeing on flame retardant properties was studied. The cotton fabrics treated with metallic salts demonstrate an excellent dyeability property. Color intensities of the dyed fabrics were measured by using a UV VIS–NIR Reflective Spectrophotometer, over the range of 200–800 nm. The results showed that, by using silver nitrate as mordant before dying, the relative color strength (K/S values) of the dyed fabrics has been increased. Water drop test and wash fastness determination (ISO 105-C01) were conducted. Also Electronic Crock meter/Rubbing Fastness Tester AATCC 8 was used to determine the color fastness of textiles. We also concluded that dyeing the plasma treated and inoculated cotton fabrics do not have any negative effect on flame retardancy of cotton fabric.     

Argon/Hexamethyldisiloxane Plasma Effects on Poly Propylene Film Surface Properties

In this work a DC plasma reactor was used for deposition of plasma polymerized coating from hexamethyldisiloxane–Ar (35/65%) mixture on polypropylene films. Surface energy parameter have been calculated using Owens–Wendt approaches with the sessile drop method are used to obtain the dispersive γ^D and polar γ^P component of surface free energy. The surface morphology of samples were investigated using scanning electron microscope. Also the chemical properties and wetability of prepared samples were tested using Fourier transform infrared spectroscopy and contact angle measurement, 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.     

Al2O3/Y2O3/ZrO2 Ceramic Composite Properties Investigation by Plasma Focus Device

The Al₂O₃–Y₂O₃–ZrO₂ eutectic composition samples were prepared using the Al₂O₃, Y₂O₃, ZrO₂ powder treated at 900 °C for 30 min, pressed at 5 ton for 15 s and sintered at 1500 °C for 2 h. The locally made dense plasma focus (DPF) system with energy 2.8 kJ was used to surface modification of these samples. The samples, mounted at distance about 2 cm from the anode, were exposed to three shots of the DPF in Ar gas at a pressure of 0.8 mbar. The phase and elemental analysis of the untreated and plasma treated samples were conducted by the Raman and EDX spectroscopy. The Raman spectroscopy showed the formation of new phases (α-Al₂O₃ and c-ZrO₂) in the treated samples. The micro-hardness of the plasma treated samples was increased by about 280 % in comparison with the untreated sample.     

(p,p) non-Rutherford backscattering analysis of silicon carbide

In this paper, (p,p) non-Rutherford elastic backscattering (NBS) measurements with 1.6 MeV proton beams have been used to determine the areal density and C/Si stoichiometric ratio in 300–1000 nm SiC_x(H_y) films deposited on silicon substrates by Chemical Vapour Deposition (CVD) using two different gas sources, methane (CH₄) and ethylene (C₂H₄). At the same time, oxygen is also found in some of these samples. The results show that (p,p) NBS can be used to determine the areal density and C/Si ratio with a reasonable accuracy, especially when samples are thick or the terminal energy of the accelerator is low for analysis using a helium beam.     

Neutron Radiography Experiments at JRR-4, (II)

Experiments have been performed at JRR-4 (Japan Research Reactor) to investigate the capability of neutron radiographic techniques in applying to the nondestructive inspection of UO₂-PuO₂ mixed-oxide fuels. The object of the inspection was to detect “Pu particles” in the mixed-oxide fuels. In place of the actual fuel, two stages of TiO₂-EU₂O₃ mixed-oxide fuel dummy samples (the 1st stage for preliminary experiments and the 2nd stage for simulating the ATR fuel) were fabricated and radiographed with the direct exposure method using a Gd converter screen and high resolution films.

Neutron radiographs of the 1st stage dummy samples showed the excellent capability of the detection technique. Those of the 2nd stage dummy samples, however, revealed the detection limit of the technique, which showed that the present technique had not enough capability to satisfy the requirements in the inspection and that improvements of the detection technique especially on the contrast should be accomplished.     

Adsorption of methyl violet and brilliant blue onto poly(vinyl alcohol) membranes grafted with N-vinyl imidazole/acrylic acid

Poly(vinyl alcohol) films were grafted with two monomers using gamma radiation, acrylic acid and N-vinyl imidazole. The ability of these membranes to adsorb the dyes, methyl violet and brilliant blue, has been investigated. The data show that untreated or alkali treated membranes adsorb methyl violet, but they did not adsorb brilliant blue. In contrast, acidic treated membranes do adsorb brilliant blue, and did not adsorb methyl violet. This indicates that these membranes could be used for the separation of both dyes. Also it was found that the dye uptake increases with the increase in the degree of grafting.     

Measurement of Thermal Neutron Cross Section of 137Cs(n, γ)138Cs Reaction

A calculational model for a modified diffusion coefficient has been developed to incorporate the neutron streaming effect in heterogeneous low-density channels accurately into diffusion theory calculations. The model uses a supercell, and the axial and radial diffusion coefficients of the heterogeneous inner cell are so defined that they can reproduce Benoist's axial and radial diffusion coefficients of the supercell when the diffusion coefficient of the outer cell is given as 1/3 Σ_tr . In the case of the axial diffusion coefficient, the axial buckling effect is taken into account by modifying the neutron path length within the streaming channel in calculating the collision probabilities. This model has been applied to an RZ fast reactor Core model with a gas expansion module (GEM). By using the axial diffusion coefficient obtained with the presented model, calculational error of GEM worth was reduced to less than 1/7 compared to the formula of Rowlands and Eaton.     

Positron beam and Raman analysis of hydrogen plasma treated and annealed Cz-Si

Positron beam annihilation Doppler-broadening (PADB) and Raman studies were carried out on H-plasma treated and annealed p-type Cz-Si. Samples were treated by a 13.56 MHz H-plasma for 2 h at RT (∼30 °C) and 250 °C, respectively. Annealing was done in air between 100 and 600 °C for annealing times between 10 and 480 min. The Raman spectra of the RT treated samples show no (or only very weak) H₂-molecule signals, in contrast to the samples H-plasma treated at 250 °C. Raman intensity changes as a function of temperature are observed, which are attributed to the evolution of voids or platelets. The positron annihilation data correlate with these results, since annealing of the RT plasma treated samples reduces the Doppler-broadening S-values with increasing temperature and/or annealing time. Together with an increasing positron diffusion length this suggests that defects acting as positron trapping centers are (partially) annealed out. For the sample plasma treated at 250 °C the following depth dependent behavior of the Doppler parameters is found. Below 100 nm depth the Doppler parameters follow the same trend as those of the RT treated samples. In a zone between 100 and 200 nm depth the S parameter strongly increases after annealing at 600 °C. This is attributed to the formation of positronium (Ps), indicative for the presence of nano-cavities capable of trapping molecular hydrogen in this region.     

Low Pressure Hexamethyldisiloxane (HMDSO)/Nitrogen Plasma Treatment on the Wettability and Surface Free Energy of Biaxial-Oriented Polypropylene (BOPP) Films

In this paper the influence of DC glow discharge HMDSO-N₂ plasma on wettability and surface properties of Biaxial-oriented polypropylene (BOPP) polymeric surfaces, has been investigated. The effects of plasma exposure time and HMDSO percent on the surface energy and wettability of the BOPP films were characterized using Fourier transform infrared spectroscopy (FTIR), Atomic force microscopy (AFM) and contact angle measurement. A clear change in the surface energy of BOPP films due to plasma treatment was observed. In this work we report changing surface properties of BOPP films instead of plasma treatment time and HMDSO ratios.     

Compact ignition test reactor (CITR)

Design considerations have been developed for a compact ignition test reactor (CITR). The objectives of this tokamak device are to achieve ignition, to study the characteristics of plasmas that are self-heated by alpha particles, and to investigate burn control. To achieve a compact design, the toroidal field magnet consists of copper-stainless steel plates to accommodate relatively high stresses; it is inertially cooled by liquid nitrogen. No neutron shielding is provided between the plasma and the toroidal field magnet. The flat-top of the toroidal field magnet is 10 s. Strong auxiliary heating is employed. In one design option, adiabatic compression in major radius is employed to reduce the neutral beam energy required for adequate penetration; thiscompression boosted design option has a horizontally elongated vacuum chamber; illustrative parameters are a compressed plasma witha=0.50 m, R=1.35 m,B _T =9.1 T, and a neutral beam power of 15 MW of 160 keVD ⁰ beams. A design option has also been developed for alarge bore device, which utilizes a circular vacuum chamber. Thelarge bore design provides increased margin and flexibility; both direct heating with RF or neutral beam injection and compression boosted startup are possible. The large bore design also facilitates the investigation of high-Q driven operation. Illustrative plasma parameters for full use of the large bore area=0.85 m,R=1.90 m, andB _T =7.5 T.     

On the measurement of 10Be on the 1 MV compact AMS system at the Centro Nacional de Aceleradores (Spain)

In this work we present the most recent improvements performed by our group on ¹⁰Be measurements on the 1 MV AMS system recently set up at the CNA (Centro Nacional de Aceleradores), in Seville (Spain). Our efforts have been focused on the study of the viability of our system for BeO and BeF^? measurements. To achieve this, different standard materials have been measured to demonstrate the reliability of the system for BeO measurements in a wide ¹⁰Be/⁹Be atomic ratio range and several environmental samples have been studied both at the 1 MV AMS CNA facility and at the 6 MV AMS ETH-PSI facility of Zurich to validate our measurements. The results show a good agreement between laboratories. New experiments also have been carried out selecting 1+ and 2+ charge states at the exit of the accelerator and inserting Si₃N_3.1 foils with different thicknesses to separate ¹⁰Be from its isobar, ¹⁰B. The influence of each foil on the overall transmission (detected ¹⁰Be compared to BeO^? injected into the accelerator) and background level was also assessed. In addition some tests were also done to assess the viability of BeF₂ and BaBeF₄ measurements at our system. Several metal matrices and cathode preparation procedures for BeO samples were investigated to maximize current and cathode lifetime.     

Interaction of hydrogen plasma with carbon-tungsten composite layer

Interaction of neutral hydrogen atoms with the layer of hydrogenated carbon-tungsten composite was studied. A 1 μm thick layer was prepared by sputter deposition from C and WC-targets in Ar/C₂-H₂ gas mixture. After deposition the samples were treated in weakly ionized highly dissociated hydrogen plasma created in a microwave discharge at a power of 1 kW. The gas flow was 13 l/h and pressure was 90 Pa. Temperature of the samples during treatment was about 850 K. After plasma treatment the samples were analyzed by AES (Auger electron spectroscopy) depth profiling, XPS (X-ray photoelectron spectroscopy) and SEM (scanning electron microscopy). It was found that during hydrogen plasma treatment selective etching of the C-W layer occurred. Carbon was preferentially removed from the C-W layer, and after about 10 min of treatment practically only tungsten with a huge porosity was detected.     

Plasma Internal Inductance in the Presence of External Resonant Fields in IR-T1 Tokamak

In this paper we presented experimental investigation of effects of local limiter biasing (V_biasing = +200 v, V_biasing = +320 v) on the plasma parameters as plasma current, loop voltage, poloidal beta, plasma pressure, plasma energy, plasma resistance, plasma temperature, plasma displacement, Shafranov parameter and plasma internal inductance in IR-T1 tokamak. For these purposes, array of magnetic probes and also a diamagnetic loop have been used. The results show that applied biased voltage V_biasing = +200 v causes to decrease of about 40 % in plasma internal inductance. The plasma resistance and the plasma displacement have been decreased by V_biasing = +200 v. The main result of the application of V_biasing = +200 v is flatting the plasma parameters profiles. In other words, the addition of biasing voltage V_biasing = +200 v to plasma could be effective for improving the quality of tokamak plasma discharge by creating the steady state plasma. The plasma current, plasma pressure, plasma energy, plasma temperature and shift parameter have increased after the application of limiter biasing with V_biasing = +320 v but they decrease rapidly.     

Determination of K shell absorption jump factors and jump ratios in the elements between Tm(Z = 69) and Os(Z = 76) by measuring K shell fluorescence parameters

The K shell absorption jump factors and jump ratios have been measured in the elements between Tm (Z = 69) and Os(Z = 76) without having any mass attenuation coefficient at the upper and lower energy branch of the K absorption edge. The jump factors and jump ratios for these elements have been determined by measuring K shell fluorescence parameters such as the total atomic absorption cross-sections, the K_α X-ray production cross-sections, the intensity ratio of the K_β and K_α X-rays and the K shell fluorescence yields. We have performed the measurements for the calculations of these values in attenuation and direct excitation experimental geometry. The K X-ray photons are excited in the target using 123.6 keV gamma-rays from a strong ⁵⁷Co source, and detected with an Ultra-LEGe solid state detector with a resolution 0.15 keV at 5.9 keV. The measured values have been compared with theoretical and others’ experimental values. The results have been plotted versus atomic number.     

Gamma ray and neutron shielding properties of some concrete materials

Shielding of gamma-rays and neutrons by 12 concrete samples with and without mineral additives has been studied. The total mass attenuation and linear attenuation coefficients, half-value thicknesses, effective atomic numbers, effective electron densities and atomic cross-sections at photons energies of 59.5 and 661 keV have been measured and calculated. The measured and calculated values were compared and a reasonable agreement has been observed. Also the recorded values showed a change with energy and composition of the concrete samples. In addition, neutron shielding has been treated in terms of macroscopic removal cross-section (Σ_R, cm⁻¹) concept. The WinXCom and NXcom programs were employed to calculate the attenuation coefficients of gamma-rays and neutrons, respectively.     

Radiation induced effects in segmented poly(siloxaneurethaneureas) based on aliphatic and aromatic diisocyanates

Poly(siloxaneurethaneureas) (PSURURs) prepared from aromatic and aliphatic isocyanates were investigated upon exposure to ionising radiation. Radicals are formed both in siloxane and urethane segments. In comparison with aliphatic analogues it was found that in aromatic PSURURs: (1) concentration of all radicals is lower, (2) relative concentration of methylene radicals formed in siloxane units is higher, (3) the radiation yield of H₂ is more than three times smaller and (4) it seems that efficiency of cross-linking is less significant.     

Plasma graft of poly(ethylene glycol) methyl ether methacrylate (PEGMA) on RGP lens surface for reducing protein adsorption

Poly(ethylene glycol)methyl ether methacrylate(PEGMA) was grafted on fluorosilicone acrylate rigid gas permissible contact lens surface by means of argon plasma induced polymerization to improve surface hydrophilicity and reduce protein adsorption. The surface properties were characterized by contact angle measurement, x-ray photoelectron spectroscopy (XPS) and atomic force microscopy respectively. The surface protein adsorption was evaluated by lysozyme solution immersion and XPS analysis. The results indicated that a thin layer of PEGMA was successfully grafted. The surface hydrophilicity was bettered and surface free energy increased. The lysozyme adsorption on the lens surface was reduced greatly.     

Plasma Confinement Modification in IR-T1 Tokamak by Velocity Shear Stabilization

E × B velocity shear effects on the plasma confinement were investigated in the IR-T1 tokamak. The investigations have been done at the presence of external applied electric and Resonant Helical magnetic Fields (RHF). In this work, experimental data have been measured by using two arrays of the Langmuir probes in both the radial and poloidal directions. A velocity shear stabilization mechanism has also been proposed to be responsible for an improvement in plasma confinement. The results show that E_r × B drift velocity (V_E×B) reduces about 90 % due to applied biasing and RHF at edge plasma. We have also observed that positive biasing and RHF lead to a significant decrease (>80 %) for radial turbulent transport (Γ_E×B) at edge plasma. In this paper, the electrostatic Reynolds stress (Rs) and the shearing rate γ_E×B have been calculated. We have also compared the Rs and γ_E×B at presence of the biasing and RHF and without biasing and RHF. A good correlation between confinement modifications and E_r × B velocity shear has been found suggesting that confinement enhancement originates at the edge plasma as a consequence of the formation of a particle transport barrier just inside the limiter.