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We investigate the generation of terahertz (THz) radiation from laser-wakefield acceleration (LWFA) in a helium gas jet. We consider a three-dimensional setup incorporating a realistic gas density distribution and use particle-in-cell simulations to study the interaction of a femtosecond intense laser pulse with the gas medium. Our results show that LWFA can efficiently produce THz radiation. In the simulations, we use multiple probes to record the electric and magnetic fields arising from the interaction. In addition, we compare the results of fixed and moving window simulation boxes used to capture electromagnetic fields in the THz range. We demonstrate that a moving window with a 600 μm width can be significantly useful for THz studies. We further analyze the spectrum of spatially and temporally resolved electromagnetic radiation and its emission angle. Our results are consistent with experimental data. Our findings provide valuable insights into the potential of LWFA as a strong source of THz radiation. [ABSTRACT FROM AUTHOR]

• Proposing a comprehensive study on the electro-thermal analysis and dynamic arc behavior of a single discharge chamber in an MCA. • Evaluating the proposed model by using the FEM method and magneto-hydrodynamic (MHD) theory. • Investigating the arc behavior inside and outside the discharge chamber. • Analyzing dynamic arc parameters such as current density, arc velocity, temperature gradient and total heat flux by considering dimensional changes of MCA. • The results indicate that the changes in distance between electrodes have more effects than other structural characteristics of MCA on dynamic arc parameters and arc motion. In order to improve the ability to extinguish the arc caused by lightning surge overvoltage, a type of smart arrester, known as multi-chamber arrester (MCA), has been developed. These arresters are used as lightning protection devices to protect the transmission and distribution lines. In this paper, a two-dimensional mathematical transient model of the MCA is presented using the finite element method (FEM). This model serves as the foundation for investigating the arc motion characteristics of the arrester and analyzing its arc-extinguishing ability. To establish an accurate representation of the arc plasma, the Magneto-hydrodynamic (MHD) theory is employed within a single discharge chamber. Subsequently, the arc motion, trajectory, and dynamic changes following an electrical breakdown event are evaluated. Additionally, the effects of discharge chamber dimensions and distance between electrodes on the arc behavior are explored. Finally, by considering the structural factors of the MCA, the dynamic arc parameters including current density, velocity, temperature gradient, and total heat flux are investigated. The simulation results reveal that the dynamic evolution of the arc in the discharge chamber is most affected by the change in distance between electrodes. [ABSTRACT FROM AUTHOR]

Greenhouse gases are major contributors to global warming, and their concentration is increasing due to the widespread use of fossil fuels. Coal bed methane (CBM) offers a potential solution to this issue. However, the gas adsorption mechanisms of CBM, particularly in the context of coal-derived asphaltenes, are not fully understood. This study provides a comprehensive theoretical investigation of the competitive adsorption of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrogen (N 2 ) in the processes of CO 2 - and N 2 -enhanced coalbed methane recovery, with a focus on coal-derived asphaltenes functionalized with CH 4 , NH, O, and S groups. Using the Grand Canonical Monte Carlo (GCMC) simulation method and performing Molecular Dynamics (MD) simulations, we studied the adsorption process. To investigate the electronic effects and nature of the interactions, we performed density functional theory (DFT) calculations. The adsorption energy values and non-covalent interactions (NCI) for the adsorption of gases signify the physical adsorption (van der Waals interaction), with CO 2 exhibiting the highest (absolute) adsorption energy. The Monte Carlo results indicated that elevated temperatures led to a reduction in adsorption capacity. Coal-derived asphaltenes demonstrated greater selectivity for CO 2 compared to CH 4 and N 2 in competitive adsorption, especially at elevated temperatures. Our findings highlight the significant potential of our asphaltene model, not only in mitigating CO 2 greenhouse gas emissions but also in recovering CH 4 , which is a valuable resource. [ABSTRACT FROM AUTHOR]