Hasil untuk "Plasma engineering. Applied plasma dynamics"

Efemena Otejiri Oliogu, Stephen Emeka Arinze, Oghenekparobo Ernest Agbogun et al.

As the global labour market becomes highly saturated, most Nigerian graduates are finding it difficult to start a sustainable career path. Hence, it is highly imperative for Nigerian graduates to be both financially literate and entrepreneurially oriented should they desire to forge a career path. This study investigated the effects of entrepreneurial orientation (EO) and financial literacy (FL) on career readiness among Accounting, Banking, and Finance students in Dennis Osadebay University (DOU), Asaba, Nigeria. A quantitative design was utilized. Questionnaires were distributed to 193 Accounting, Banking, and Finance students in the Faculty of Management Sciences. 25 students were surveyed to test the questionnaire’s reliability using Cronbach’s alpha. Regression analysis was the primary estimation technique used to test the relationships among financial literacy, entrepreneurial orientation, and career readiness. Cognitive factors (financial literacy) and behavioural factors (entrepreneurial orientations such as innovativeness, proactiveness, and risk-taking) are positively associated with students’ career readiness. These findings underscore that both financial literacy and entrepreneurial orientation are critical factors shaping students’ career readiness.

Z. Bai, Yi Zhang, Cong Chen

Raymond J. Arebalo, Augustin J. Sanchez, Nathan Tompkins

Microfluidic devices are used in numerous scientific fields and research areas, but device fabrication is still a time- and resource-intensive process largely confined to the cleanroom or a similarly well-equipped laboratory. This paper presents a method to create microfluidic devices in under three hours using the silicone polymer polydimethylsiloxane (PDMS) and a laser cut positive master using PDMS double casting without a cleanroom or other large capital equipment. This method can be utilized by an undergraduate student with minimal training in a laboratory with a modest budget. This paper presents “Same Day Microfluidics” as a fabrication method accessible to research groups not currently fabricating their own microfluidic devices and as an option for established research groups to more quickly create prototype devices. The method is described in detail with timing, materials, and technical considerations for each step and demonstrated in the context of a Y-channel coflow device.

Gururaj Hatti, Rushikesh Shinde, Sandesh Mindolkar et al.

Metal Matrix Composites offer superior mechanical properties compared to monolithic alloys, making them highly suitable for demanding engineering applications. This study investigates the mechanical behavior of an Aluminum 7075 alloy reinforced with Tungsten Carbide (WC) and Cow Dung Ash (CDA) fabricated via stir casting. The primary objective of this study was to evaluate the effect of hybrid reinforcement on the composite's hardness. The results indicated that the incorporation of WC and CDA significantly enhanced the hardness of the Al 7075 matrix. Specifically, the hybrid composite containing 3.5 wt.% WC and 1.5 wt.% CDA exhibited the highest hardness (35 HRB), representing a substantial improvement compared to the lower-WC compositions studied. These findings suggest that modifying Al 7075 with WC and CDA is a viable strategy for developing cost-effective high-strength composites.

Jiachen Tong, Haiying Li, Bin Xu et al.

Deep learning technologies have been widely used in fluid data processing to reconstruct various flow fields. However, due to the complex particle dynamics, relying exclusively on data-driven methods lacks reflection of physical mechanisms. In this article, an electron density reconstruction model of sensor data based on a physics-informed convolutional transposed neural network (PICTNN) is proposed. Employing the continuity equation of plasmas, a physics-informed loss function is constructed to enhance model stability during training through logarithmic maximum normalization. As a validation of the method, based on the density dataset of wakes obtained using the computational fluid dynamics method, the 2-D reconstruction of plasma wakes under different Mach numbers and angles of attack (AOAs) is tested. The results demonstrate excellent preservation of physical features, with Pearson correlation coefficients between the reconstructed data and the computational fluid dynamics simulations reaching up to 0.95. Additionally, this model has been successfully applied to reconstruct 2-D wake distributions from 1-D measurement data. The wake electron density reconstruction model may enhance the effective use of experimental data and extend the measurement capabilities of hypersonic wake devices, offering significant engineering implications.

Xinlei Zheng, Haotian Zheng, Zihan Sun et al.

The discharge and surface charge dynamics, as well as the local streamer-to-filament transition of a three-electrode surface discharge under repetitive nanosecond pulses with a frequency of 1 kHz at atmospheric pressure, are studied through experiments and simulations. Evolutions of plasma morphology and electric field vector, as obtained by an intensified charge-coupled device camera and an improved electric field induced second harmonic method, respectively, are utilized to analyze discharge dynamics. A 2D fluid model combined with a 0D kinetic model is established to study the accumulation behavior of surface charge and mechanism of the local streamer-to-filament transition. The simulation results demonstrate a qualitative agreement with the experimental measurements on the discharge evolution, waveforms of discharge current and key features of the electric field. The results show that a three-electrode surface discharge includes three discharge phases: the primary streamer, local enhanced discharge and reverse breakdown. The local enhanced discharge occurs near the high-voltage (HV) electrode, characterized by a local streamer-to-filament transition and subsequent emission belt parallel to the edge of HV electrode, after the primary streamer bridges the two electrodes. The local streamer-to-filament transition is attributed to the local accumulation of active species with a lower threshold energy in the high field region (∼25 kV cm−1) similar to that of the secondary streamer in pin-plane discharges. The emission belt is formed by the high-density charge spot at the filament head, a phenomenon attributable to charge migration under the influence of an applied electric field. The spatial non-uniformity of plasma channel is a general feature in non-uniform field discharges and is a key process that induces the discharge mode transition.

L. Fulcheri, E. Dames, V. Rohani

M. Scarpari, X. Zhang, K. Borowiec et al.

Plasma disruptions represent a critical challenge for high-performance tokamak operations, as they can compromise machine integrity and reduce operational availability. Although future fusion devices essentially need to incorporate strategies to minimise disruption occurrence, complete avoidance remains unattainable. Consequently, assessing and characterising unmitigated disruption consequences is fundamental for the design and qualification of next-generation fusion power plants. This work supports the pre-conceptual design of ST-E1, a low aspect-ratio Tokamak Fusion Power Plant developed by Tokamak Energy Ltd., by presenting a comprehensive disruption modelling approach applied across different design stages. The methodology integrates both physics and engineering considerations to evaluate the impact of disruptions on machine performance and structural integrity. From an engineering perspective, several ST-E1 layout options were analysed to investigate the electromagnetic response of key components under disruption-induced loads, enabling comparison between alternative design solutions. On the physics side, a broad set of disruption scenarios was explored, scanning operational space parameters, plasma-material interactions, and associated thermal loads. Furthermore, the study examined variations in disruption behaviour arising from different reference equilibria, focusing on a range starting from Double Null to Single Null configurations, reflecting the increasing up-down asymmetry consequences. The results reveal significant contrasts in plasma dynamics and structures electromagnetic behaviour between configurations, highlighting the importance of disruption modelling in guiding design choices. These analyses have proven instrumental in shaping ST-E1 development, offering critical insights for mitigating risks and optimising future fusion reactor designs.

N. Savard, G. Fubiani, M. Dehnel

Recent studies have shown that variations in particle-per-cell count and cell size can significantly affect the accuracy of 1D implicit energy- and charge-conserving electrostatic particle-in-cell simulations of capacitively coupled radio frequency discharges, even when the sheath is resolved and the quasi-neutral region is relaxed. This challenges the expected advantages of implicit schemes and may stem from the complexity of active stochastic sheath heating. To test whether passive sheaths can mitigate this issue, we study a similar 1D discharge with perpendicular electron heating, which produces passive sheath dynamics. We find that the same resolution sensitivity persists: coarser spatial resolution requires more particles per cell and still yields reduced accuracy compared to well resolved solutions. Furthermore, we observe that in our implementations, it is difficult to identify simulation parameters (time step, cell size, and particle-per-cell count) where implicit schemes are both more accurate and faster than momentum-conserving explicit codes. On non-uniform grids, we show that energy-conserving explicit and implicit methods yield similar results when the time step is small. Finally, we explore how trends in the resultant discharge characteristics vary with reduced resolution in energy-conserving simulations beyond what is feasible with momentum-conserving explicit schemes and find that while overall trends are generally preserved, the specific values and the magnitude of their changes can differ significantly.

W. Ling, C. Jing, J. Wan et al.

Our earth is immersed in the near-earth space plasma environment, which plays a vital role in protecting our planet against the solar-wind impact and influencing space activities. It is significant to investigate the physical processes dominating the environment, for deepening our scientific understanding of it and improving the ability to forecast the space weather. As a crucial part of the National Major Scientific and Technological Infrastructure–Space Environment Simulation Research Infrastructure (SESRI) in Harbin, the Space Plasma Environment Research Facility (SPERF) builds a system to replicate the near-earth space plasma environment in the laboratory. The system aims to simulate the three-dimensional (3-D) structure and processes of the terrestrial magnetosphere for the first time in the world, providing a unique platform to reveal the physics of the 3-D asymmetric magnetic reconnection relevant to the earth's magnetopause, wave–particle interaction in the earth's radiation belt, particles’ dynamics during the geomagnetic storm, etc. The paper will present the engineering design and construction of the near-earth space plasma simulation system of the SPERF, with a focus on the critical technologies that have been resolved to achieve the scientific goals. Meanwhile, the possible physical issues that can be studied based on the apparatus are sketched briefly. The earth-based system is of great value in understanding the space plasma environment and supporting space exploration.

Hao Shang, W. Ning, Saikang Shen et al.

C. Bonneville, Youngsoo Choi, D. Ghosh et al.

Numerically solving partial differential equations (PDEs) can be challenging and computationally expensive. This has led to the development of reduced-order models (ROMs) that are accurate but faster than full order models (FOMs). Recently, machine learning advances have enabled the creation of non-linear projection methods, such as Latent Space Dynamics Identification (LaSDI). LaSDI maps full-order PDE solutions to a latent space using autoencoders and learns the system of ODEs governing the latent space dynamics. By interpolating and solving the ODE system in the reduced latent space, fast and accurate ROM predictions can be made by feeding the predicted latent space dynamics into the decoder. In this paper, we introduce GPLaSDI, a novel LaSDI-based framework that relies on Gaussian process (GP) for latent space ODE interpolations. Using GPs offers two significant advantages. First, it enables the quantification of uncertainty over the ROM predictions. Second, leveraging this prediction uncertainty allows for efficient adaptive training through a greedy selection of additional training data points. This approach does not require prior knowledge of the underlying PDEs. Consequently, GPLaSDI is inherently non-intrusive and can be applied to problems without a known PDE or its residual. We demonstrate the effectiveness of our approach on the Burgers equation, Vlasov equation for plasma physics, and a rising thermal bubble problem. Our proposed method achieves between 200 and 100,000 times speed-up, with up to 7% relative error.

David A Schulenberg, M. Vass, M. Klich et al.

The effects of neutral gas heating along the direction of the gas flow inside the discharge channel of a parallel plate micro atmospheric pressure plasma jet, the COST-jet, on the spatio-temporal dynamics of energetic electrons are investigated by experiments and simulations. The plasma source is driven by a single frequency sinusoidal voltage waveform at 13.56 MHz in helium with an admixture (0.05–0.2%) of nitrogen. Optical emission spectroscopy measurements are applied to determine the spatio-temporally resolved electron impact excitation dynamics from the ground state into the He I (3s)3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^3$$\end{document}S1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_1$$\end{document} state and the rotational temperature of nitrogen molecules at different positions along the direction of the gas flow inside the 30 mm long discharge channel. The gas temperature, which is assumed to be equal to the N2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document} rotational temperature, is found to increase along the discharge channel. This effect is attenuated as the nitrogen concentration is increased in the gas mixture, leading to an eventually constant temperature profile. The experimental data also reveal a plasma operating mode transition along the discharge channel from the Ω\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Omega$$\end{document}- to the Penning-mode and show good agreement with the results of 1d3v kinetic simulations, which spatially resolve the inter-electrode space and use the gas temperature as an input value. The simulations demonstrate that the increase of the gas temperature leads to the observed mode transition. The results suggest the possibility of using the nitrogen admixture and the feed gas temperature as additional control parameters, (i) to tailor the plasma operating mode along the direction of the gas flow so that the production of specific radicals is optimized; and (ii) to control the final gas temperature of the effluent. The latter could be particularly interesting for biological applications, where the upper gas temperature limit is dictated by the rather low thermal damage threshold of the treated material.

M. Scarpari, S. Minucci, G. Sias et al.

Nuclear fusion is entering the era of power plant-scale devices, which are now undergoing extensive studies to support the design phase. Plasma disruptions pose a high risk to these classes of devices because of the large stored thermal and magnetic energy which might jeopardize machine integrity and availability. Therefore, disruptions within these devices must be virtually eliminated, and any disruptions which do happen must be highly mitigated. However, the characterisation, prediction and technology used to mitigate disruptions is still an area of active development. In this paper, the authors investigate the disruptions within ST40, with particular attention at the identification of causes and effects associated with disruptions, both from a physics basis and an engineering standpoint. This paper aims at presenting preliminary predictive analyses of ST40 plasma scenarios by exploiting Machine Learning techniques applied to an experimental database populated by plasma pulses executed during the ST40 2021–2022 experimental campaign. The database contains both disrupted and non-disrupted pulses. Using Machine Learning, common features within disruptions are automatically classified and identified, mapping the controllable operational space in terms of plasma displacement and variation of specific plasma internal parameters. The classification was validated by benchmarking the numerical reconstruction of the plasma dynamics with experimental data recovered from the plasma diagnostics. Subsequent Machine Learning analyses allowed the extrapolation of new disrupted plasma configurations for preliminary predictive simulations of the plasma column displacement. Thanks to the numerical simulations performed in MAXFEA environment, it is possible to investigate the plasma vertical displacement both during disrupted and regularly terminated plasma scenarios and to provide lessons to be learnt for the next ST40 experimental campaign and for the design of future ST devices.

S. Barman, S. Bhattacharjee

Micro-glass capillaries emerge as an important tool for the lossless guiding and focusing of ion beams (Kojima 2018 J. Phys. B: At. Mol. Opt. Phys. 51 042001). The self-focusing mechanism of the capillaries is primarily governed by charged patches induced on their inner walls by the incident beam (Stolterfoht et al 2002 Phys. Rev. Lett. 88 133201). However, the dominance of space charge forces over self-focusing forces in intense (J ≈ 1 A m−2) ion beams establishes a self-focusing limit (Maurya et al 2019 J. Phys. D: Appl. Phys. 52 055205), posing challenges to beam focusing beyond this limit. In this work, a novel method is introduced, demonstrating electrical control over the charge patch dynamics through an externally applied bias voltage, thereby enabling the focusing of Ar ion beams beyond the self-focusing limit. Experimental results reveal that adjusting the biasing voltage allows overcoming the self-focusing limit, resulting in the generation of a high-intensity ( Jout≈3.05×105 A m−2) nano-beam (∼160 nm). Furthermore, electrical control is shown to enhance the performance of both straight and tapered capillaries (SC/TC), with the TC being more effective for nano-beam generation. A Particle-In-Cell (PIC) simulation code has been developed to explain the experimental results. The implications of high-intensity nano ion beams in advancing nanopatterning, nanoscale material analysis, and matter wave interferometry, underscore significant contributions to research and innovation within electronics, materials science, nanotechnology, and emerging quantum technologies.

M. I. Baranov

Goal. Development of the generalized physical principle of development of plasma channel of a high-voltage electrical pulse spark discharge in the homogeneous dielectric of the different aggregate state. Methodology. Basis of physical optics, theoretical electrical engineering, electrophysics bases of technique of high-voltage and large pulse currents, bases of high-voltage pulse technique and measuring technique. Results. Development of physical principle of development of plasma channel of an electric pulse spark discharge is executed in a homogeneous gas dielectric on the applied example of the use in calculations and experiments of the double-electrode discharge system (DEDS) with a long air interval, testing action of standard interconnect аperiodic pulse of high-voltage of temporal shape of Tm/Тd≈200 μs/1990 μs of positive polarity. The generalized formula is got for the calculation of total length of lc of the real way of development of an pulse spark discharge in an air dielectric, which allowed to formulate the offered physical principle in the following kind: «The plasma channel of an pulse spark discharge in a gas dielectric spreads from one of its points to other after a way length of lc, providing the least falling on it of electric voltage of Uc». It is shown that this principle in the first approaching can be applied and to the homogeneous liquid and hard dielectrics. Comparison of the developed physical principle of distribution of plasma channel of an electrical spark discharge is executed in a dielectrical environment with fundamental Fermat physical principle (a law) for distribution of light in an optically transparent environment, which specifies on mathematical likeness and closeness on destiny of these physical principles. Calculation estimations of falling of electric voltage of Uc on total length of lc of the real zigzag way of development in the air dielectric of DEDS a «edge-plane» with the least length of its discharge interval of lmin=1,5 m is presented, that a value Uc does not exceed 9 % from the experimental level of aggressive voltage of Umd≈611,6 кV in this DEDS for the аperiodic pulse of voltage of Tm/Тd≈200 μs/1990 μs. It is set that the estimated time of td advancement of leader channel of electric pulse discharge in air DEDS (lmin=1,5 m) on its real way total length of lc≈1,53 m makes td≈15,3 μs, and experimental duration of cut of Tdc of the indicated аperiodic impulse of voltage utilized in experiments, characterizing time of short circuit by the plasma channel of discharge of air interval in DEDS, appears equal Тdc≈td≈17 μs. Originality. The generalized physical principle of development of plasma channel of a high-voltage electrical pulse spark discharge is first developed in the homogeneous dielectric of the different aggregate state. Practical value. Application in electrical engineering practice and high-voltage pulse technique of the offered principle of distribution in the dielectrics of plasma channel of an pulse spark discharge will allow to develop both new and to perfect the existent methods of computer design of electro-discharge processes in the gas, liquid and hard insulation of different high-voltage electrical power engineering and electrophysics devices, directed on the increase of reliability of their operation.

N. S. Alharthi, R. Tolba

The present study focuses on investigating the properties of finite nonlinear ion-electrostatic pulses in a multicomponent plasma consisting of two positive ions and superthermal electrons. Understanding the behavior and characteristics of these pulses is crucial for gaining insights into the dynamics and phenomena occurring within these plasmas. Here, hydrodynamic equations that account for both ions and superthermal electrons are used to derive a Sagdeev potential as an analytical tool to analyze the pulses. The aim of the investigation is to explore the conditions under which large-amplitude solitary waves can exist in this plasma system. Numerical analysis techniques are also employed to examine how various plasma parameters influence the characteristics of these solitary waves by analyzing their corresponding Sagdeev potentials. A novel direct method is further applied to investigate the basic behavior exhibited by electrostatic excitations within this system by solving potential equations directly. This research not only sheds light on fundamental aspects but also reveals new solutions within these potentials that allow for different types of wave propagation, including solitary or explosive pulses as well as periodic or shock-like waves. The findings from this investigation have significant implications for furthering the understanding of complex plasmas and may help in identifying ionized particles escaping from Titan’s atmosphere.

N. Nassiri-Mofakham

The nonlinear structure and dynamics of dispersive solitons and breather waves described by Korteweg‐de Vries and nonlinear Schrödinger equations are studied. The theoretical and numerical study of the generalized hydrodynamic equations, accounting for wave dissipation and particle production‐loss mechanism, are considered. The reductive expansion method has been used in the context of the instability problem of multi‐fluid dynamics, applied to the study of electrostatic solitons and ion‐acoustic waves. A nonlocal model of interacting solitary‐breather waves has been presented. Applications of the theory, concerning the ion streaming instability in the framework of plasma physics, are presented.

Pratik Ghosh, B. Chaudhury, Shishir Purohit

Microwave interactions reveal electromagnetic properties of complex materials like plasma that aid in under-standing plasma’s wide range of applications in manufacturing, aerospace, and more. The interactions generally comprise transmission, absorption, and scattering of microwaves with the dense plasma profile. Traditional computational methods face a challenge in simulating the complex interaction between the microwave and asymmetric plasma profiles due to the trade-off between the number of computations and the accuracy of the result, which encourages exploring other techniques. Data-driven deep learning techniques due to their ability to decipher hidden pattern from input data finds application in solving various advanced scientific/engineering problems. The technique has been applied to investigate complex microwave plasma interactions. The proposed deep learning model, trained on different asymmetric plasma profiles and corresponding scattered microwave E-field patterns, achieved 300-500 times faster and accurate predictions that are within acceptable limits. Thus, affirms the model’s applicability in accelerating future studies on plasma dynamics.

M. Zhang, C. Sang, M. Zhao et al.

Efficient handling of high heat flux on the plasma‐facing components, particularly the divertor targets, poses a significant challenge for the Chinese Fusion Engineering Testing Reactor (CFETR) with fusion power of Gigawatt. This work investigates the divertor plasma detachment of CFETR with a standard ITER‐like divertor geometry by neon (Ne) or argon (Ar) impurity seeding using UEDGE code. The cross‐field drifts terms are switched off, and fluid neutral models and a “fixed‐fraction” impurity model are applied to enable efficient simulations for the study of CFETR detachment. In order to reduce the heat load on the divertor targets below the acceptable level (<10 MW/m2), the impurity fraction (f), pumping speed (S), and upstream density are varied to identify the suitable operations window during Ne seeding. The effects of Ne and Ar impurities on the plasma detachment are compared. It is found that with the power across the core‐edge interface PSOL = 200 MW and separatrix density of 2.8  ×$$ \times $$  1019 m−3$$ {\mathrm{m}}^{-3} $$ , Ne impurity fraction ≥1.7%, and Ar impurity fraction ≥0.24% can achieve the partial detachment. Achieving similar total radiation power (˜148 MW), the Ne fraction is 2.3% and the Ar fraction is 0.24%. Moreover, the simulation results indicate that Ar exhibits better power radiation efficiency and core compatibility compared with Ne.