N2 Ratio Research Articles

Reactive oxygen and nitrogen species in Ar + N2 + O2 atmospheric-pressure nanosecond pulsed plasmas in contact with liquid

In this paper, a nanosecond pulse gas-liquid discharge is generated in Ar and Ar with admixtures of N2 or O2. The discharge images and waveforms of pulse voltage and discharge current are used to characterize gas-liquid discharge characteristics; optical emission spectroscopy and Fourier-transform infrared spectroscopy are employed to diagnose the reactive species in the gas phase, and chemical probe methods are employed to investigate plasma-induced reactive species (H2O2, NO2−, and NO3−) in the liquid phase. The effects of added contents of N2 or O2 in Ar discharge on the formation of reactive species are investigated. It is found that the productions of gaseous O and O3 increase obviously with the increasing O2 ratio and the productions of gaseous N2 (C-B), NO, NO2, and N2O increase with the increasing N2 ratio. Additionally, for the reactive species measured in the liquid phase, the increase in the N2 ratio in Ar discharge is beneficial for increasing the concentrations of NO3− and NO2− and decreasing the concentrations of H2O2, while the increase in the O2 ratio in Ar discharge decreases the concentrations of H2O2 and inhibits the production of NO2−.

Tillage, compaction and wetting effects on NO3, N2O and N2 losses

Denitrification is sensitive to changes in soil physical properties that affect solute transport, air content and gas diffusion. Using lysimeters, containing intact soil from intensively tilled (IT) and no-tilled (NT) soil used to grow forage crops, we examined how simulated animal treading at different moisture contents (above and below field capacity; >FC and <FC respectively) affected losses of nitrous oxide (N2O), dinitrogen (N2) and nitrate (NO3). We applied 15N-labelled NO3 (250kg N ha–1) to the soil surface after treading (applied at 220 kPa to 40% of the soil surface), or to untrodden soil. Drainage occurred following weekly application of water over the experiment (two pore volumes over 84 days). Treading at >FC greatly increased denitrification, especially from IT soil and produced the greatest amount of N2 (64kg N ha–1), N2O (8.2kg N ha–1), as well as the lowest N2O to N2O+N2 ratio (0.08) and NO3 leaching (136kg N ha–1 below 30cm). In both the uncompacted or compacted soils <FC, emissions of N2O were greater (1.5–2.7% of N applied) and the N2O to N2O+N2 ratios were closer to 0.2 compared to compaction at >FC. Treading at <FC had minimal or no effect on denitrification compared to untrodden soil. Fluxes of N2 and N2O were strongly influenced by the weekly irrigation–drainage cycle. The N2 production and reduction in NO3 leaching were best correlated with increases in microporosity and reduced saturated hydraulic conductivity following treading. Although recovery of 15N was high (84.3%), the remainder of the balance was likely lost as either N2 or, of greater concern, as N2O. Practically, animal trampling on wet soils, especially when recently cultivated, should be avoided.

Optimisation of gaseous nitriding process parameters for hard surface layer of duplex stainless steel

The optimisation for gaseous nitriding process parameters of duplex stainless steel was performed using Taguchi approach. The nitriding process parameters of temperature, time and gas mixture ratio of NH3 and N2 are considered as input parameters. Three responses are chosen which are surface hardness, wear weight loss and coefficient of friction. The optimum process parameters for surface hardness and coefficient of friction are similar with 550°C, 16 hour and 0.3 NH3/N2. The study revealed that temperature and time are the most significant factor influencing the responses of nitrided surface of DSS. The formation of hard surface layer contains expanded austenite with thickness layer until 135 μm and maximum hardness of 1,440 Hv. The hardness values produced five times greater than untreated DSS. The worn surface after wear test has improved with mild wear and smooth abrasion mark.

Optimisation of gaseous nitriding process parameters for hard surface layer of duplex stainless steel

The optimisation for gaseous nitriding process parameters of duplex stainless steel was performed using Taguchi approach. The nitriding process parameters of temperature, time and gas mixture ratio of NH3 and N2 are considered as input parameters. Three responses are chosen which are surface hardness, wear weight loss and coefficient of friction. The optimum process parameters for surface hardness and coefficient of friction are similar with 550°C, 16 hour and 0.3 NH3/N2. The study revealed that temperature and time are the most significant factor influencing the responses of nitrided surface of DSS. The formation of hard surface layer contains expanded austenite with thickness layer until 135 μm and maximum hardness of 1,440 Hv. The hardness values produced five times greater than untreated DSS. The worn surface after wear test has improved with mild wear and smooth abrasion mark.

The change of carbohydrate antigen 19-9 as a prognostic marker after neoadjuvant chemotherapy in patients with borderline resectable and locally advanced pancreatic cancer

Introduction: Although the patients with neoadjuvant chemotherapy (NACT) showed better survival than those who underwent upfront surgery for borderline resectable (BRPC) and locally advanced pancreatic cancer (LAPC), prognostic markers for responders was not confirmed. Method: BRPC (n = 81, 69.2 %) and LAPC (n = 36, 30.8 %) patients who underwent surgery after NACT were included from 2012 to 2017 in tertiary referral center. They were divided into 2 groups based on carbohydrate antigen (CA) 19-9 regression rate (CRR) of 65 % before and after NACT and oncologic outcome was compared. Result: The median pre and post-chemotherapy CA19-9 were 137 U/ml (IQR: 32-371) and 28.7 U/ml (IQR: 13-94.6), respectively. CRR < 65 % (n = 59) showed higher N2 ratio than CRR ≥ 65 % group (n = 58) significantly (20.3 % vs 1.7%, p = 0.021) in perioperative results. Otherwise, there were no significant differences including imaging response (partial response on preoperative computed tomography; 32.2 vs 48.3 %, p = 0.091, maximum standardized uptake value on positron emission tomography; 4.5 vs 3.8, p = 0.310), pathologic tumor regression grade (5.6 vs 11.1 %, p = 0.489) and R1 resection rate (28.8 vs 19.0%, p = 0.279) between CRR < 65 % and CRR ≥ 65 % groups. The patients with CRR ≥ 65 % showed better survival than patients with CRR < 65 % (n = 59) (median survival; 26 vs 47 months, p = 0.024). Multivariate analysis revealed that CRR < 65 % was independent prognostic factor in survival (hazard ratio [HR]; 2.096, p = 0.025, 95% confidence interval [CI]; 1.095-4.009) and recurrence (HR; 1.583, p = 0.053, 95% CI; 0.994-2.523). Conclusion: CRR after NACT can be used for prognostic marker in patients with BRPC and LAPC. However, other markers are needed to evaluate resectability after NACT.

Ternary and quarternary TiBN and TiBCN nanocomposite coatings deposited by arc ion plating

Binary TiN monolayer coating cannot meet the demands of the industrial application. a route for improving its performance is the addition of new element: silicon, boron or carbon. Therefore the main objective of this work is the preparation of TiBN and TiBCN coatings with a nanocomposite structure offering a higher micro-hardness as well as an improved wear resistance. Arc ion plating was used for the deposition of the TiBN and TiBCN coatings on Si (100) and cemented carbide substrates. TiBN nanocomposites coatings was deposited using TiB2 composite target in pure N2 whereas for TiBCN coatings was in mixed C2H2 and N2. The components, microstructure and mechanical properties behavior of the nanocomposite coatings were investigated. TiBN coatings consisted of the crystalline phases TiN, TiB2 and amorphous BN. A maximum micro-hardness of about 3160 HV was observed at a 0.5 Pa N2 pressure while the micro-hardness correlates well with N2 pressure. TiBCN coatings prepared with the N2 and C2H2 process exhibit a nanocomposite structure of nanocrystalline TiN and TiB2, morphous C, CN and BN. Compared to TiBN, lower micro-hardness of the TiBCN coatings down to 1761 HV was measured for at 1/2 gas flow ratio of C2H2 and N2. For grinding material cemented carbide, the friction coefficient of TiBN coating was nearly 0.4 while the friction coefficient of TiBCN coatings was lower 0.2 with the increasing of C2H2 and N2 flow ratio.

Growth and characterization of InxAl1−xN films on silicon substrate by magnetron sputtering method

In this paper, InxAl1−xN films were prepared on silicon substrate by magnetron sputtering method. By changing the sputtering conditions of InxAl1−xN films such as substrate temperature, working pressure, gas flow ratio, the films with different crystalline and surface microstructure were prepared which lead to different performances of the films. The crystalline of the films was measured by x-ray diffraction (XRD), and the surface morphology and roughness of the films was characterized by scanning electron microscope (SEM). The results showed that the microstructure of InxAl1−xN film grown when the substrate temperature, the working pressure and the flow ratio of Ar and N2 are 600 °C, 0.6 Pa and 20:20 sccm respectively, is best in as-prepared InxAl1−xN films under different processing conditions, the indium content of the film is x = 0.69, and the preferred crystalline orientation of the film is (002) planes. The properties of InxAl1−xN films were measured by Hall test system and Raman analysis instrument. Hall test results showed that the mobilities of the films are between 300 cm2 V−1s−1 and 800 cm2 V−1s−1, and the carrier concentrations are between 9.8 × 1017 cm−3 and 3.2 × 1019 cm−3. Raman analysis indicated that the film has obvious A1(LO) and E2(high) optical phonon modes. In a word, the films prepared under optimized conditions have good electrical properties and less stress, so InxAl1−xN films can have great potential to be used for high-frequency devices.

Nanosecond pulsed uniform dielectric barrier discharge in atmospheric air: A brief spectroscopic analysis.

The paper proposes a simple and convenient approach to represent the discharge uniformity of nanosecond-pulse dielectric barrier discharge (DBD) in air by observation of the ratio of N2+ (B3Σu+ → X3Σg+, 0-0, 391.4 nm) to N2 (C3Πu → B3Πg, 2-5, 394.3 nm) intensities. The DBDs at different pulse peak voltages, discharge gap distances, dielectric materials and thicknesses were investigated by recording their single-pulse-shot discharge images and N2+/N2 ratios to verify the feasibility of the above innovative approach. The results show that the ratios of N2+/N2 are in the range of 0.18-0.6within our experimental parameters, which is respect to the reduced electric field (E/N, where E is the field strength and N is gas number density) strength of 260-440 Td (1 Td = 10-17 V·cm2). And it is indicated that a lower N2+/N2 ratio would be found in a higher pulse peak voltage or/and a lower discharge gap distance, which benefits for improving the discharge uniformity of nanosecond-pulse DBD. The thickness and permittivity of dielectric material also affect the E/N strength and discharge uniformity to a certain extent, but the effects are ambiguous due to additional factors of dielectric materials. In addition, the theoretical basis and application scope of this approach were also discussed.

Studying the influence of nitrogen seeding in a detached-like hydrogen plasma by means of numerical simulations

The leading candidate for impurity seeding in ITER is currently nitrogen. To date, there have only been a few studies on the plasma chemistry driven by N2/H2 seeding and its effect on the molecular-activated recombination of incoming atomic hydrogen ions in a detached-like scenario. Numerical simulations are needed to provide insights into such mechanisms. The numerous plasma chemical reactions that may occur in such an environment cannot be entirely included in a 2- or 3-dimensional code such as Eirene. A complete global plasma model, implemented with more than 100 plasma chemical equations and 20 species, has been set up on the basis of the Plasimo code. This study shows that two main nitrogen-including recombination reaction paths are dominant, i.e. the ion conversion of NH followed by dissociative recombination, and the proton transfer between and N2, producing N2H+. These two processes are referred to as N-MAR (nitrogen molecular-activated recombination) and have subsequently been implemented in Eunomia, which is a spatially resolved Monte Carlo code designed to simulate the neutral inventory in linear plasma machines such as Pilot-PSI and Magnum-PSI. To study the effect of N2 on the overall recombination, three studies have been set up, and from a defined puffing location with a constant total seeding rate of H2 + N2, three N2 ratios were simulated, i.e. 0%, 5% and 10%. The parameter monitored is the density of atomic hydrogen, being the final hydrogenic product of any recombination mechanism in the scenario considered. The difference in H density between the 0% case and the 10% case is about a factor of three. The importance of NH as an electron donor is highlighted, and the N-MAR reaction routes are confirmed to enhance the conversion of ions to neutrals, making the heat loads to the divertor plate more tolerable. This work is a further step towards a full understanding of the role of N2-H2 molecules in a detached divertor plasma.

Effects of ultraviolet C, controlled atmosphere, and ultrasound pretreatment on free ferulic acid in canned sweet corn kernels.

Because canned sweet corn kernel (CSCK) products are subject to high market competitiveness, producing them with a higher content of free ferulic acid (FFA), a functional ingredient, using non-thermal and green technologies may be an alternative solution for Thai exporters. This study aimed to investigate the effects of pre-canning ultraviolet C (UVC), controlled atmosphere (CA), and ultrasound treatments on the FFA content, texture, and colour of CSCKs. UVC irradiation (0, 1.94 and 4.01kJ/m2) was tested in combination with storing corn under CA at %O2:%CO2:%N2 ratios of 21:0.03:78, 3:10:87, and 3:15:82 before canning. Based on the FFA content, two UVC-CA pretreatments were selected for the ensuing experiment. The effects of the selected UVC-CAs in combination with 0, 10, or 20min of 35kHz ultrasound before canning were measured. The FFA content, moisture, texture, and colour of the CSCKs treated with the nine UVC-CA combinations were not significantly different. Corn irradiated with 1.94kJ/m2 UVC and stored under 3:15:82 %O2:%CO2:%N2 before canning exhibited the highest FFA content, followed by corn treated with no UVC and stored at 3:15:82 %O2:%CO2:%N2. Corn treated with ultrasound combined with the two selected UVC-CA treatments showed no differences in FFA content, moisture, texture, or colour. Corn kernels treated with UVC-CA-ultrasound had a higher FFA content than untreated kernels. UVC-CA-ultrasound pretreatment showed a trend of increasing CSCK FFA content with no change in physical properties. Thus, UVC-CA-ultrasound pretreatment appears to be an alternative process that might add value to CSCKs by increasing FFA content.

Control of Ion Species and Energy in High-Flux Helicon-Wave-Excited Plasma Using Ar/N2 Gas Mixtures

The atomic nitrogen (N) ion flux and impacting ion energy are the two important parameters, which influence the performance of production of plasma nitridation applications such as N-doped graphene. In this paper, a novel method is described to control the flux and ion energy of atomic N ion (N+) and molecular N2 ion (N2+) using a helicon-wave-excited plasma (HWP) with Ar/N2 gas mixtures. It shows that by varying the flow-rate ratio of N2/(N2+Ar) ( $\alpha$ ), the ratio of [N+]/[N2+] ( $\beta$ ) can be controlled obviously, and $\beta $ could be increased up to 1.2 at $\alpha = 0.5$ , which is much higher than that in pure N2 HWP discharge ( $\beta \sim 0.2$ ). The maximum density and flux of atomic N+ are obtained, which are $2.5\times 10^{18}\,\,\text {m}^{-3}$ and $8.6\times 10^{21}\,\,\text {m}^{-2}\text {s}^{-1}$ , respectively. The results show that the addition of Ar into N2 plasma can be employed to remarkably increase the [N+]/[N2+] due to electron-impact ionization involving the metastable state of Ar. The N+ ion beams are formed with a speed near to Mach 3, and the ion-beam energy is increased from 30 to 50 eV with increasing $\alpha $ to 0.75.

Total electron content responses to HILDCAAs and geomagnetic storms over South America

Abstract. Total electron content (TEC) is extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. This subject is of greatest importance for space weather applications. Under disturbed conditions the two main sources of electric fields, which are responsible for changes in the plasma drifts and for current perturbations, are the short-lived prompt penetration electric fields (PPEFs) and the longer-lasting ionospheric disturbance dynamo (DD) electric fields. Both mechanisms modulate the TEC around the globe and the equatorial ionization anomaly (EIA) at low latitudes. In this work we computed vertical absolute TEC over the low latitude of South America. The analysis was performed considering HILDCAA (high-intensity, long-duration, continuous auroral electrojet (AE) activity) events and geomagnetic storms. The characteristics of storm-time TEC and HILDCAA-associated TEC will be presented and discussed. For both case studies presented in this work (March and August 2013) the HILDCAA event follows a geomagnetic storm, and then a global scenario of geomagnetic disturbances will be discussed. Solar wind parameters, geomagnetic indices, O ∕ N2 ratios retrieved by GUVI instrument onboard the TIMED satellite and TEC observations will be analyzed and discussed. Data from the RBMC/IBGE (Brazil) and IGS GNSS networks were used to calculate TEC over South America. We show that a HILDCAA event may generate larger TEC differences compared to the TEC observed during the main phase of the precedent geomagnetic storm; thus, a HILDCAA event may be more effective for ionospheric response in comparison to moderate geomagnetic storms, considering the seasonal conditions. During the August HILDCAA event, TEC enhancements from ∼ 25 to 80 % (compared to quiet time) were observed. These enhancements are much higher than the quiet-time variability observed in the ionosphere. We show that ionosphere is quite sensitive to solar wind forcing and considering the events studied here, this was the most important source of ionospheric responses. Furthermore, the most important source of TEC changes were the long-lasting PPEFs observed on August 2013, during the HILDCAA event. The importance of this study relies on the peculiarity of the region analyzed characterized by high declination angle and ionospheric gradients which are responsible for creating a complex response during disturbed periods.

Nitrogen-rich hyper-crosslinked polymers for low-pressure CO2 capture

A series of poly[methacrylamide-co-(ethylene glycol dimethacrylate)] (poly(MAAM-co-EGDMA)) porous polymeric particles with high CO2-philicity, referred to as HCP-MAAMs, were synthesised for CO2 capture. The polymers with a MAAM-to-EGDMA molar ratio from 0.3 to 0.9 were inherently nitrogen-enriched and exhibited a high affinity towards selective CO2 capture at low pressures. A techno-economic model based on a 580 MWel supercritical coal-fired power plant scenario was developed to evaluate the performance of the synthesised adsorbents. The presence and density of NH2 moieties within the polymer network were determined using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The thermogravimetric analysis (TGA) showed that the polymers were thermally stable up to 515–532 K. The maximum CO2 adsorption capacity at 273 K was 1.56 mmol/g and the isosteric heat of adsorption was 28–35 kJ/mol. An increase in the density of amide groups within the polymer network resulted in a higher affinity towards CO2 at low pressure. At a CO2:N2 ratio of 15:85, CO2/N2 selectivity at 273 K was 52 at 1 bar and reached 104 at ultra-low CO2 partial pressure. The techno-economic analysis revealed that retrofitting a HCP-MAAM-based CO2 capture system led to a net energy penalty of 7.7–8.0%HHV points, which was noticeably lower than that reported for MEA or chilled ammonia scrubbing capture systems. The specific heat requirement was superior to the majority of conventional solvents such as MDEA-PZ and K2CO3. Importantly, the economic performance of the HCP-MAAM retrofit scenario was found to be competitive to chemical solvent scrubbing scenarios.

Emission spectroscopy of expanding laser-induced gaseous hydrogen-nitrogen plasma.

Microplasma is generated in an ultra-high-pure H2 and N2 gas mixture with a Nd:YAG laser device that is operated at the fundamental wavelength of 1064 nm. The gas mixture ratio of H2 and N2 is 9 to 1 at a pressure of 1.21 ± 0.03 105 Pa inside a chamber. A Czerny-Turner-type spectrometer and an intensified charge-coupled device are utilized for the recording of plasma emission spectra. The line-of-sight measurements are Abel inverted to determine the radial distributions of electron number density and temperature. Recently derived empirical formulas are utilized for the extraction of values for electron density. The Boltzmann plot and line-to-continuum methods are implemented for the diagnostic of electron excitation temperature. The expansion speed of the plasma kernel maximum electron temperature amounts to 1 km/s at a time delay of 300 ns. The microplasma, initiated by focusing 14 ns, 140 mJ pulses, can be described by an isentropic expansion model.

Global analysis of agricultural soil denitrification in response to fertilizer nitrogen

Terrestrial soil denitrification is of great importance for closing the nitrogen (N) cycle, yet the current understanding of soil denitrification response to N fertilization remains uncertain. While there has been a focus on factors controlling N2O fluxes from agricultural soils because of its global warming effect, much less is known about factors controlling total denitrification losses, yet these can be sufficiently large to affect N use efficiency. Here, we collated 353 observations from 74 papers and conducted a global-scale meta-analysis to explore the effects of N fertilization on agricultural soil denitrification (N2O+N2) where the acetylene inhibition technique was used. Relative to the control, N fertilization significantly increased soil denitrification by an average of 174%, although the magnitude of this increase differed significantly across environmental and soil conditions. Soil denitrification was more responsive to N fertilization in grasslands than in croplands. The changes in soil denitrification increased exponentially when the rates of synthetic N fertilizer application≤250kgNha−1, but above this threshold, there were no further increases. The responses of soil denitrification to N fertilization were negatively correlated with soil clay content, C:N ratio, and bulk density. The comparable responses of soil N2O emissions (165%) and denitrification to N fertilization resulted in a small insignificant decrease of the N2O:N2 ratio. Organic fertilizer applied with and without synthetic N fertilizer can contribute to lower N2O emissions probably by facilitating the last step of soil denitrification to N2 production. Taken together, we conclude that these findings can provide important insights on regulating soil denitrification, which might contribute to improvement of N use efficiency and elimination of its negative impacts in agro-ecosystems.

Colossal permittivity of carbon nanotubes grafted carbon fiber-reinforced epoxy composites

Giant dielectric-constant-ceramic materials have been paid much attention for their potential applications in high-capacity capacitors due to their high energy storage density. Dielectric constants of composite materials are generally low compared with ceramic materials. In this paper, carbon nanotubes (CNTs) were successfully prepared on carbon fibers (CFs) surface by chemical vapor deposition (CVD) and CNTs-CFs/epoxy composites were obtained by hot-pressure molding. Effects of CVD atmosphere on composites dielectric performance were investigated. The composites exhibited a surprisingly high dielectric constant about 200,000 (60 kHz) when the ratio of C2H2, H2 and N2 was 6:6:12 in the CVD process.

Nitrogen Losses in Sediments of the East China Sea: Spatiotemporal Variations, Controlling Factors, and Environmental Implications

AbstractGlobal reactive nitrogen (N) has increased dramatically in coastal marine ecosystems over the past decades and caused numerous eco‐environmental problems. Coastal marine sediment plays a critical role in N losses via denitrification and anaerobic ammonium oxidation (anammox) and release of nitrous oxide (N2O). However, both the magnitude and contributions of denitrification, anammox, and N2O production in sediments still remain unclear, causing uncertainty in defining the N budget for coastal marine ecosystems. Here potential rates of N losses, and their contributions and controlling factors, were investigated in surface sediments during six cruises from 429 sites of the East China Sea. The potential rates of denitrification, anammox, and N2O production varied both spatially and seasonally, but the contribution of anammmox to total N2 production (%anammox) and N2O:N2 ratio only varied spatially. Both organic carbon and nitrate (NO3−) were important factors controlling N losses, N2O:N2 ratio, and %anammox. Our results also showed that marine organic carbon induced by eutrophication plays an important role in stimulating reactive N removal and increasing N2O production in warm seasons. The sediment N loss caused by denitrification, anammox, and N2O production in the study area were estimated at 2.2 × 106 t N yr−1, 4.6 × 105 t N yr−1, and 8 × 103 t N yr−1, respectively. Although sediments remove large quantities of reactive N, they act as an important source of N2O in this region influenced by NO3−‐laden rivers.

DEPOSITION AND CHARACTERIZATION OF MAGNETRON CO-SPUTTERED InAlN FILM AT DIFFERENT Ar:N2 GAS FLOW RATIOS

This work presents the influence of changing Ar:N2 gas ratio on the growth and properties of InAlN films. InAlN films were deposited on [Formula: see text]-type Si(111) substrates by using magnetron co-sputtering method in 6:12, 10:10, 12:8 and 12:6 Ar:N2 mixtures at 300[Formula: see text]C. The surface, structural, electrical and optical properties of the deposited films were evaluated at different Ar:N2 ratios. The grain size and film thickness were increased by increasing the Ar flow with respect to N2. Structural characterization by X-ray diffraction (XRD) revealed an improvement in the crystalline quality of the [Formula: see text]-axis-oriented InAlN film by adjusting the Ar:N2 ratio to 12:8, however no diffraction peak corresponding to InAlN was detected at 6:12 Ar:N2 mixture. The surface roughness of InAlN film exhibited an increasing trend whereas the electrical resistivity of the film was decreased by increasing the Ar:N2 ratio. The bandgap of InAlN film was calculated from the optical reflectance spectra and it was found to change by changing the Ar:N2 gas ratio. The analysis of results from this work shows that the InAlN film with improved physical properties can be obtained through reactive magnetron co-sputtering method by adjusting the Ar:N2mixture to 12:8.

Nitridated Pd/B4C multilayer mirrors for soft X-ray region: internal structure and aging effects.

Reactive sputtering with a mixture of argon and nitrogen (N2 partial pressure of 4%, 8%, and 15%) as the working gas is used to develop the high reflectance Pd/B4C multilayers for soft X-ray region application. Compared to the pure Ar fabricated sample, the interface roughness of the nitridated multilayer is slightly increased while the compressive stress is essentially relaxed from -623 MPa (pure Ar) to -85 MPa (15% N2). A maximum reflectance of 32% is measured at the wavelength of 9.5 nm for the multilayer fabricated with 15% N2. After storing the multilayers in an air environment for 6-17 months, a distinct aging effect is observed on the nitridated samples. The transmission electron microscopy results indicate that a large part of the top layers of the nitridated samples is deteriorated with severe interdiffusion, essential decrease in d-spacing, and compacted multilayer structure. The deterioration is less pronounced for the multilayers fabricated with a higher ratio of N2. Energy dispersive X-ray spectroscopy reveals that the concentration of nitrogen and boron in the degraded area is much reduced compared to the intact layers. A primitive model of upward diffusion of nitrogen and boron is proposed to explain the aging effects of the nitridated structure.

Experimental studies on the power–frequency breakdown voltage of CF3I/N2/CO2 gas mixture

Trifluoroiodomethane is a promising alternative to SF6 because of its good insulation properties and much less serious greenhouse effect than SF6. Previous studies have shown that the insulation performance of CF3I mixed with CO2 or N2 can equal that of SF6. This study explored the frequency breakdown characteristics of CF3I and SF6 mixed with two buffer gases. The effects of air pressure and field strength were analyzed. The fixed mixing ratio of CF3I and SF6 was 30% in the experiment. The breakdown experiment was conducted by changing the mixing ratio of CO2 and N2. Results showed that the CO2/N2 mixture ratio did not exert a synergetic effect, and the CF3I/CO2 breakdown performance was better than that of CF3I/N2 in the quasi-uniform and highly non-uniform electric fields. CO2 possibly provided the C atoms for the entire system to maintain a certain balance in C, and this balance inhibited the decomposition of CF3I. The breakdown performance of SF6/N2 was good in quasi-uniform field, whereas that of SF6/CO2 was good in the highly non-uniform field.