Hasil untuk "Plasma engineering. Applied plasma dynamics"

Praveena Kakarla, Vimala C

Lung diseases remain a major global health concern, affecting the supply of oxygen to other parts of the body. There are several types of lung diseases, including asthma, COPD, and pneumonia. Numerous methods have been developed to identify these lung diseases; however, they still have several shortcomings, including long processing times, complex structures, and poor classification accuracy. To address these issues, a lung disease classification system is developed using the proposed method. First, pre-processing techniques are applied to improve image quality by reducing noise and enhancing contrast using Modified Histogram Equalization and Cross-guided Bilateral Filtering. The images are collected from the NIH ChestX-ray dataset. Next, Extended Lyrebird Optimization is utilized to select the optimal features, and the Squeeze-Excited DenseNet201 (SE-DenseNet201) model is employed for feature extraction. Finally, an Atrous Convolutional Self-Attention-based Capsule Network model is utilized for classification, and the Kookaburra Optimization Algorithm is employed for hyperparameter tuning. The proposed approach is evaluated using the NIH ChestX-ray dataset and achieves an accuracy of 92.70%, with 92.13% precision and 92.99% recall.

A. S. Joglekar, A. G. R. Thomas

Vlasov-Poisson-Fokker-Planck (VPFP) simulations of large-amplitude electron plasma waves, where the bounce frequency is much larger than the collision frequency, $ω_B \gg ν_\text{ee}$, show that the evolution of these waves exhibits three phases; I. A short-lived trapping phase during which collisional effects are minimal. II. A long-lived detrapping phase during which collisional effects are most influential. III. A short-lived Landau damping phase where the effect of collisions becomes minimal again. While the dispersion relation during the trapping and Landau damping phase is well known, the wave behavior during the detrapping phase is not as well understood. The simulations show that during the detrapping phase, the interplay between weak electron-electron collisions and strong wave-electron interactions results in an increasing frequency shift further from the linear root, $ω_\text{EPW}$. At the conclusion of the detrapping phase, the distribution function is nearly Maxwellian, the frequency shift rapidly diminishes, and the wave damps at a larger rate than the Landau damping rate. Empirical fits to the damping rates, frequency shift enhancement rate, and the lifetime of the plasma waves are provided as functions of collision frequency, wavenumber, and wave amplitude.

Sandeep Malik, A. Akbulut, U. Demirbilek et al.

K. Eder, A. Stegmeir, W. Zholobenko et al.

We report on developments in the edge and scrape-off layer turbulence code GRILLIX to self-consistently simulate plasma turbulence coupled to a fluid neutral gas model. The neutrals model is extended from a single fluid moment (neutrals density) to three moments, describing additionally the dynamics of neutrals parallel momentum and neutrals pressure. GRILLIX employs the flux-coordinate-independent (FCI) approach, wherein the mesh is neither conformal to the wall nor the magnetic field. A new flux evaluation method consistent with FCI allows for implementing plasma recycling at the boundaries that preserves particles to high precision. The improved plasma-neutrals model is applied to simulate an ASDEX Upgrade attached L-mode discharge. Diffusion and viscosity of neutrals parallel momentum introduce a loss channel for ion parallel momentum. This increases the plasma-neutrals interaction time, which is expected to facilitate detachment. Evolution of neutrals pressure leads to a smoother neutrals distribution. Through the charge-exchange coupling, fluctuation amplitudes of ion temperature filaments in the divertor region are reduced. When additionally applying self-consistent recycling boundary conditions, neutrals density and ionization rates at the strike-lines further increase, which impacts the heat load distribution on the target plates.

Stijn Van Rompaey, E. Morais, G. Stefanidis et al.

This study explores the electrical, optical, and thermal properties of nanosecond pulsed plasmas at pressures ranging from 0.5 to 2.0 bar in a pure CH4 atmosphere. The plasma pulse energy was assessed using various techniques to identify the most accurate method, while outlining the limitations of others. The most accurate method indicates a plasma pulse energy between 6 and 15 mJ that drops with increasing pressure at a constant applied voltage. Optical characterisation involved time-resolved discharge dynamics through high-resolution intensified charge-coupled device imaging with optical filters and optical emission spectroscopy. This approach allowed to assess the pressure effect on plasma volume and electron density, which were found to range from 0.66 to 1.00 mm3 and 7.0–10.5 × 1017 cm−3, respectively. The high electron density indicates that the plasma operates in spark mode, achieving ionisation levels up to 5.6%. Additionally, the gas heating kinetics were explored using CH(A) and C2 Swan band emissions, validated by Rayleigh scattering spectroscopy, revealing the gas heating dynamics up to 35 µs. The peak temperature decreases from 3082 K to 1070 K upon increasing pressure from 0.5 to 2.0 bar at constant plasma pulse energy of 12 mJ. Soot generation was also investigated, revealing a significant pressure dependence, with the onset of particle growth time increasing exponentially from 15 μs at 0.5 bar to 60 μs at 2.0 bar. These findings suggest that this nanosecond pulsed spark plasma operates in a highly non-equilibrium state, with high electron density. Altogether, this work offers a comprehensive characterisation of a CH4 nanosecond pulsed plasma, establishing a foundation for optimising its application in hydrocarbon conversion processes.

K. Kourtzanidis, S. Starikovskaia

Nanosecond discharges are characterized by a shift in energy branching toward the excitation of electronic levels and dissociation, making them particularly attractive for plasma chemistry. Understanding the spatio-temporal structure of these discharges is especially important. This paper presents a detailed 2D-axisymmetric numerical analysis of a nanosecond discharge propagating in a long tube and in pure nitrogen. The modeling is conducted using a self-consistent plasma fluid solver under the local mean energy approximation, including photoionization. The discharge develops at moderate pressures, 1–10 Torr, in the form of a fast ionization wave (FIW). Simulations are performed for both negative and positive polarities of the voltage pulse applied to the high-voltage electrode. The computational results are validated against available experimental data, including FIW velocity within the studied pressure range, electron density, longitudinal electric field, and the radial distribution of N2(C  3Πu ) emission on a nanosecond timescale.

Daniel A. L. V. Cunha, F. M. Marega, L. A. Pinto et al.

Plasma surface treatment of ceramic particles has emerged as a promising approach for developing biocomposites intended for use in tissue engineering applications. Introducing functional groups on particle surfaces promotes changes in material surface properties, enhancing adhesion, biocompatibility, and reactivity. It can also mitigate degradation during the processing of polymer matrices in composite materials. Therefore, carefully choosing the functionalizing agent responsible for generating the functional groups and selecting appropriate functionalization parameters are significant steps in the plasma surface treatment process. However, in a tissue engineering context, an excess of the functionalizing agent can be harmful, increasing cell toxicity and inhibiting the stimulation of cell growth, consequently delaying or even hindering tissue regeneration. This article examines how the functionalizing agent excess of l-lactic acid (LA) applied in the plasma surface treatment of the filler affects the thermal, rheological, biological, and wettability properties of poly(lactic acid) (PLA) and zinc oxide (ZnO) biocomposites. The investigation reveals that the surface treatment effectively mitigated the catalytic effects of ZnO on PLA degradation during melt processing, regardless of the excess functionalizing agent. There was minimal impact on the material’s rheological, thermal, and wettability characteristics, but the LA residue significantly influenced cell proliferation and the biological response. These findings show the importance of removing excess functionalizing agents to obtain biocomposites suitable for tissue engineering applications.

Lan-Yue Luo, Z. Donkó, R. Masheyeva et al.

The effect of oxygen admixture in an argon capacitively coupled radio-frequency plasma is investigated experimentally and computationally in a symmetrical discharge cell, at pressures ⩽10 Pa. In the experiments, tunable diode laser absorption spectroscopy is applied to monitor the densities of the Ar 1s5 ( →772.376nm 2p6) and 1s3 ( →772.421nm 2p2) metastable atoms in the plasma as a function of the oxygen content in the working gas. In order to enhance computational efficiency, the modelling is divided into two steps. First, the electron energy probability function (EEPF) is obtained from a particle-in-cell/Monte Carlo collision simulation of the Ar/O2 plasma without considering the dynamics of the excited levels of Ar atoms. As the second step, this EEPF is fed into a code that solves the balance equations of Ar atoms in numerous excited levels. These equations comprise the effects of diffusion, direct and stepwise excitation processes, stepwise and pooling ionization, as well as radiative transfer between the various Ar atomic levels, and the quenching of the excited Ar atoms by O2 molecules. Using this approach is justified by the fact that the EEPF is insensitive to the excited level dynamics at low pressures, as shown in previous studies. The measurements and simulations are found to yield consistent results, indicating the correctness of the literature values of the quenching coefficient of Ar 1s5 and 1s3 by oxygen molecules.

Suyog Amrutrao

This study presents India’s import and export patterns with its top ten trading partners. It aims to identify the variables that impact India’s trade ties and their implications for its economic growth. The paper examines trade data, market trends, and monetary policies. The study highlights the advantages and disadvantages of India’s international trade framework, focusing on key commodities, trade volumes, and bilateral trade agreements. The outcome shows how strategically significant these top trading partners have been in shaping India’s trade environment and provides insight into possible areas of policy action to improve trade performance. This study contributes to the understanding of India’s role in the global trade landscape and provides recommendations for fostering more substantial and equitable trade relationships.

Mashael M. AlBaidani

The time-fractional generalized Burger–Fisher equation (TF-GBFE) is utilized in many physical applications and applied sciences, including nonlinear phenomena in plasma physics, gas dynamics, ocean engineering, fluid mechanics, and the simulation of financial mathematics. This mathematical expression explains the idea of dissipation and shows how advection and reaction systems can work together. We compare the homotopy perturbation transform method and the new iterative method in the current study. The suggested approaches are evaluated on nonlinear TF-GBFE. Two-dimensional (2D) and three-dimensional (3D) figures are displayed to show the dynamics and physical properties of some of the derived solutions. A comparison was made between the approximate and accurate solutions of the TF-GBFE. Simple tables are also given to compare the integer-order and fractional-order findings. It has been verified that the solution generated by the techniques given converges to the precise solution at an appropriate rate. In terms of absolute errors, the results obtained have been compared with those of alternative methods, including the Haar wavelet, OHAM, and q-HATM. The fundamental benefit of the offered approaches is the minimal amount of calculations required. In this research, we focus on managing the recurrence relation that yields the series solutions after a limited number of repetitions. The comparison table shows how well the methods work for different fractional orders, with results getting closer to precision as the fractional-order numbers get closer to integer values. The accuracy of the suggested techniques is greatly increased by obtaining numerical results in the form of a fast-convergent series. Maple is used to derive the approximate series solution’s behavior, which is graphically displayed for a number of fractional orders. The computational stability and versatility of the suggested approaches for examining a variety of phenomena in a broad range of physical science and engineering fields are highlighted in this work.

Prithvi Basu

Two-photon polymerization (2PP) is revolutionizing micro- and nanoscale manufacturing by enabling true 3D fabrication with feature sizes far below the diffraction limit—capabilities that traditional lithography cannot match. By using ultrafast femtosecond laser pulses and nonlinear absorption, 2PP initiates polymerization only at the laser’s focal point, offering unmatched spatial precision. This paper highlights key advancements driving the field forward: the development of new materials engineered for 2PP with improved sensitivity, mechanical strength, and the introduction of high-speed, parallelized fabrication strategies that significantly enhance throughput. These innovations are shifting 2PP from a prototyping tool to a viable method for scalable production. Applications now range from custom biomedical scaffolds to complex photonic and metamaterial structures, demonstrating their growing real-world impact. We also address persistent challenges—including slow writing speeds and limited material options—and explore future directions to overcome these barriers. With continued progress in materials and hardware, 2PP is well positioned to become a cornerstone of next-generation additive manufacturing.

Xolile Fuku, Ilunga Kamika, Tshimangadzo S. Munonde

A national energy crisis has emerged in South Africa due to the country’s increasing energy needs in recent years. The reliance on fossil fuels, especially oil and gas, is unsustainable due to scarcity, emissions, and environmental repercussions. Researchers from all over the world have recently concentrated their efforts on finding carbon-free, renewable, and alternative energy sources and have investigated microbiology and biotechnology as a potential remedy. The usage of microbial electrolytic cells (MECs) and microbial fuel cells (MFCs) is one method for resolving the problem. These technologies are evolving as viable options for hydrogen and bioenergy production. The renewable energy technologies initiative in South Africa, which is regarded as a model for other African countries, has developed in the allocation of over 6000 MW of generation capacity to bidders across several technologies, primarily wind and solar. With a total investment value of R33.7 billion, the Eastern Cape’s renewable energy initiatives have created 18,132 jobs, with the province awarded 16 wind farms and one solar energy farm. Utilizing wastewater as a source of energy in MFCs has been recommended as most treatments, such as activated sludge processes and trickling filter plants, require roughly 1322 kWh per million gallons, whereas MFCs only require a small amount of external power to operate. The cost of wastewater treatment using MFCs for an influent flow of 318 m³ h⁻¹ has been estimated to be only 9% (USD 6.4 million) of the total cost of treatment by a conventional wastewater treatment plant (USD 68.2 million). Currently, approximately 500 billion cubic meters of hydrogen (H₂) are generated worldwide each year, exhibiting a growth rate of 10%. This production primarily comes from natural gas (40%), heavy oils and naphtha (30%), coal (18%), electrolysis (4%), and biomass (1%). The hydrogen produced is utilized in the manufacturing of ammonia (49%), the refining of petroleum (37%), the production of methanol (8%), and in a variety of smaller applications (6%). Considering South Africa’s energy issue, this review article examines the production of wastewater and its impacts on society as a critical issue in the global scenario and as a source of green energy.

Richard Amorin, Eric Broni-Bediako, Eric Stemn

Liquefied Petroleum Gas (LPG) is gaining high usage as a domestic fuel worldwide. The Government of Ghana is determined to increase access to 50% by 2030. However, due to its high flammability, unsafe gas usage has resulted in various casualties nationwide. This work, therefore, assessed the safety knowledge and handling of LPG across three cities in the Western Region of Ghana. A total of 1144 LPG users participated in the research. Information gathered included the origin and material used for cylinder manufacturing, cylinder integrity test, refilling, transportation, storage, leakage detection and rectification, cylinder maintenance, safety valves, and other accessories such as LPG hoses and burners. The assessment showed that most users lacked basic safety knowledge regarding safe gas handling. It was evident that 99.2% had never examined and pressure-tested their cylinders for integrity purposes, with 98.0% not knowing when their cylinders would be due for either disposal or a mandatory pressure test. Further, the majority transported and stored their gas cylinders incorrectly. Also, 30.4% have been using their hoses for ≥ 5 years, with the majority replacing them not based on the recommended usage period but rather on damage. These practices are alarming, warranting an urgent need to intensify safety education on the safe use of this greener fuel. Several practical implications of the research that can improve the safe handling and use of LPG at the household level have been discussed.

Chin-An Ku, Geng-Fu Li, Chen-Kuei Chung

With the evolution of micro/nanotechnology, anodic aluminum oxide (AAO) has received attention for sensor applications due to its regular and high-aspect-ratio nanopore structure with an excellent sensing performance, especially for electrical and optical sensors. Here, we propose the application of these capacitance and porous properties in a facile nanoporous AAO liquid sensor and study an efficient and economical method for preparing AAO substrates for liquid-phase substance sensing. By applying hybrid pulse anodization (HPA), a growth rate of approximately 5.9 μm/h was achieved in AAO fabrication. Compared to traditional low-temperature (0–10 °C) and two-step anodization with a growth rate of 1–3 μm/h, this process is significantly improved. The effect of pore widening on the performance of electrical sensors is also investigated and discussed. After pore widening, the capacitance values of AAO for air as a reference and various liquids, namely deionized water, alcohol, and acetone, are measured as 3.8 nF, 295.3 nF, 243.5 nF, and 210.1 nF, respectively. These results align with the trend in the dielectric constants and demonstrate the ability to clearly distinguish between different substances. The mechanism of AAO capacitive liquid-phase sensors can mainly be explained from two perspectives. First, since an AAO capacitive sensor is a parallel capacitor structure, the dielectric constant of the substance directly influences the capacitance value. In addition, pore widening increases the proportion of liquid filling the structure, enabling the sensor to clearly differentiate between substances. The other is the affinity between the substance and the AAO sensor, which can be determined using a contact angle test. The contact angles are measured as values of 93.2° and 67.7° before and after pore widening, respectively. The better the substance can fully fill the pores, the higher the capacitance value it yields.

Zhaohui Wu, Hao Peng, Xiaoming Zeng et al.

We present the first experimental realization of a four-dimensional (4D) plasma hologram capable of recording and reconstructing the full spatiotemporal information of intense laser pulses. The holographic encoding is achieved through the interference of a long object pulse and a counter-propagating short reference pulse, generating an ionized plasma grating that captures both spatial and temporal characteristics of the laser field. A first-order diffractive probe enables the retrieval of encoded information, successfully reconstructing the spatiotemporal profiles of Gaussian and Laguerre-Gaussian beams. The experiment demonstrates the ability to encode artificial information into the laser pulse via spectral modulation and retrieve it through plasma grating diffraction, high-lighting potential applications in ultraintense optical data processing. Key innovations include a single-shot, background-free method for direct far-field spatiotemporal measurement and the obser-vation of laser focus propagation dynamics in plasma. The plasma grating exhibits a stable lifetime of 30-40 ps and supports high repetition rates, suggesting usage for high-speed optical switches and plasmatic analog memory. These advancements establish plasma holography as a robust platform for ultrafast laser manipulation, with implications for secure optical communication, analog computing,and precision spatiotemporal control of high-intensity lasers.

Chenhua Ren, Bangdou Huang, Cheng Zhang et al.

The surface charge dynamics due to the interaction between a nanosecond pulsed atmospheric pressure plasma jet (APPJ) and a grounded dielectric surface is investigated by two-dimensional axisymmetric fluid simulation. The development of APPJ can be divided into three stages: (1) the primary discharge, (2) the return and forward strokes, and (3) surface ionization wave (SIW). It is verified that the forward stroke plays a critical role on the polarity of surface charges, which can be further controlled by pulse parameters (e.g. pulse width and voltage amplitude). The enhanced forward stroke, characterized by an elevated electric field with a relatively uniform distribution along the APPJ channel, raises the potential drop across the plasma column and creates the conditions for the field reversal near the target. These flip the axial electric field and drive electrons moving towards the target, as a result of which, the polarity of surface charges reverses. This indicate that as the potential drop cross the plasma column exceed the applied voltage, the direction of electric field revers and can cause the polarity reversion of surface charge. Thus, the reversal instant can happen at the voltage plateau, the voltage falling edge or after the applied voltage has reduced to zero. Due to the time sequence of surface charge reversing at different radial positions, which induces a remarkable radial field component, a negative SIW further develops along the dielectric target. As feedback, this phenomenon results in both enhanced net charge transfer to the dielectric and intensive energy deposition (electron Joule heating) of APPJ in the vicinity of the target. This study opens a new route towards the application optimization of APPJ in multiple fields via the feedback effect of surface charges on APPJ-surface interaction.

Karan Sharma, Manishkumar D. Yadav, Abhishek Sharma et al.

Abstract The rapid accumulation of plastic waste due to its non-biodegradability and increasing global consumption presents a significant environmental challenge. Conventional thermochemical waste management techniques, such as pyrolysis and gasification, offer partial solutions but suffer from secondary pollutant formation, inefficiencies, and scalability issues. Thermal plasma-assisted processes, operating at extreme temperatures of 1,500–5,000 °C, present a promising alternative by leveraging high-energy plasma arcs to achieve complete waste destruction, converting plastic into syngas and inert slag while minimizing hazardous by-products like dioxins and tars. Despite being studied over decades, the commercialization of plasma technologies remains limited due to high capital costs, proprietary technology barriers, and suboptimal reactor designs. The scalability of these systems depends on optimizing energy efficiency and feedstock adaptability, which can be addressed through advanced reactor design. This review systematically evaluates thermal plasma technology for plastic waste treatment through chemical engineering analysis of plasma-specific reaction kinetics under rapid heating conditions, coupled heat/mass modelling in high-temperature reactors, and computational optimization of torch configurations and reactor geometries. Key knowledge gaps are analyzed, including electrode erosion dynamics, plasma gas selection trade-offs, unaddressed radiation effects, and lack of thermal plasma-specific kinetic-modelling and experimentation, while presenting strategies to overcome these limitations through both modeling and experimental approaches.

A. Qadri, Niaz Wali, Muhammad Farooq et al.

Ensuring access to clean water, particularly in industrial settings, remains a significant challenge in the 21st century. Conventional wastewater treatment methods often suffer from inefficiencies, high operational costs, and limited scalability, necessitating the development of advanced, cost-effective, and sustainable alternatives. This study investigates the potential of underwater plasma discharge for flowing wastewater treatment under high fluid flow rates, focusing on the impact of discharge parameters—particularly applied voltage and frequency—on plasma dynamics. Optical emission spectroscopy was used to characterize key plasma parameters, including electron temperature ( Te), gas temperature (Tg), and electron number density (ne). Degradation experiments were conducted in both oxygen-enriched and ambient air conditions at a fixed flow rate of 0.3 l min−1, achieving a degradation efficiency of 63.57% for methylene blue (MB) and 65.24% for rhodamine B (Rh-B) in the presence of 400 SCCM  oxygen flow rate. In contrast, degradation efficiencies in air were 52.47% for MB and 55.50% for Rh-B. Compared to conventional dye degradation techniques, this method offers rapid and efficient pollutant breakdown in continuously flowing samples, demonstrating its potential as a scalable and energy-efficient plasma-based water treatment technology.

S. L. Yap, L. H. Muhammad, H. Tan et al.

This study investigates the complex relationship between different cathode radii (b) and neutron yield ( $Y_{n}$ ), for the 2.73-kJ United Nations University/International Centre for Theoretical Physics Plasma Fusion Facility (UNU/ICTP PFF) plasma focus (PF) device when gas admixtures are introduced. The Lee model code is applied to characterize the UNU/ICTP PFF and for optimizing deuterium and argon (D:Ar) neutron production. The latest codes revealed how varying cathode radii and gas admixtures affect $Y_{n}$ and plasma dynamics. The maximum computed $Y_{n}$ generated per shot is $2.42\times 10^{7}$ n with beam energy of 80.7 kJ at a gas admixture weight ratio of ca. 19% and the pure D counterpart produced $9.57\times 10^{6}$ n with a beam energy of 68.97 kJ, both corresponding to 2.0-cm cathode radii. This shows a significant increase of ca. 153%. The study revealed that $Y_{\mathrm {th}}$ made a negligible contribution to the total $Y_{n}$ . The pinch lifetime increases with increasing proportion of Ar gas. As the Ar weight ratio increases, the overall mass of the plasma increases, due to heavier Ar atoms.

Nadja Raab, Nikolas Zeh, Robin Kretz et al.

Especially for the production of artificial, difficult to express molecules a further development of the CHO production cell line is required to keep pace with the continuously increasing demands. However, the identification of novel targets for cell line engineering to improve CHO cells is a time and cost intensive process. Since plasma cells are evolutionary optimized for a high antibody expression in mammals, we performed a comprehensive multi-omics comparison between CHO and plasma cells to exploit optimized cellular production traits. Comparing the transcriptome, proteome, miRNome, surfaceome and secretome of both cell lines identified key differences including 392 potential overexpression targets for CHO cell engineering categorized in 15 functional classes like transcription factors, protein processing or secretory pathway. In addition, 3 protein classes including 209 potential knock-down/out targets for CHO engineering were determined likely to affect aggregation or proteolysis. For production phenotype engineering, several of these novel targets were successfully applied to transient and transposase mediated overexpression or knock-down strategies to efficiently improve productivity of CHO cells. Thus, substantial improvement of CHO productivity was achieved by taking nature as a blueprint for cell line engineering.