A numerical simulation of a pulsed floating electrode dielectric barrier discharge (FE-DBD) at atmospheric pressure, used for melanoma cancer cell therapy, is performed using a plasma model in COMSOL Multiphysics software. Distributions of electron density, space charge, and electric field are presented at different instants of the pulsed argon discharge. Significant results related to the characteristics of the plasma device used, the inter-electrodes distance, and the power supply are obtained to improve the efficiency of FE-DBD apparatus for melanoma cancer cell treatment. The FE-DBD presents a higher sensitivity to short pulse durations, related to the accumulated charge over the dielectric barrier around the powered electrode. At higher applied voltage, more energy is injected into the discharge channel and an increase in electron density and electric consumed power is noted. Anticancer activity provided by the FE-DBD plasma is improved using a small interelectrode distance with a high electron emission coefficient and a high dielectric constant with a small dielectric thickness, allowing higher electron density, generating reactive species responsible for the apoptosis of tumor cells.

A three-dimensional numerical modelling of a time-dependent, turbulent thermal plasma jet was developed to synthetize silicon nanopowder. Computational fluid dynamics and particle models were employed via COMSOL Multiphysics^®v. 5.4 (COMSOL AB, Stockholm, Sweden) to simulate fluid and particle motion in the plasma jet, as well as the heat dependency. Plasma flow and particle interactions were exemplified in terms of momentum, energy, and turbulence flow. The transport of nanoparticles through convection, diffusion, and thermophoresis were also considered. The trajectories and heat transfer of both plasma jet fields, and particles are represented. The swirling flow controls the plasma jet and highly affects the dispersion of the nanoparticles. We demonstrate a decrease in both particles’ velocity and temperature distribution at a higher carrier gas injection velocity. The increase in the particle size and number affects the momentum transfer, turbulence modulation, and energy of particles, and also reduces plasma jet parameters. On the other hand, the upstream flame significantly impacts the particle’s behavior under velocity and heat transfer variation. Our findings open the door for examining thermal plasma impact in nanoparticle synthesis, where it plays a major role in optimizing the growth parameters, ensuring high quality with a low-cost technique.

The main purpose of the present work consists in the study of supply frequency and sodium vapor pressure effects on the sodium lamp properties. The retained model is a two-temperature channel type that reproduces quite well the electrical and thermal behaviors as well as the main radiative characteristics of mercury-sodium discharge plasma and can be easily coupled with the lamp circuitry software.

In this research, we studied the performance analysis of inductively coupled radiofrequency plasma “RF-ICP” torch used in multi-material processing. A 2D numerical model built with COMSOL Multiphysics was used to study the discharge behavior and evaluate the overall efficiency transmitted into the plasma system. The temperature and velocity flow of the plasma were investigated. The numerical results are consistent with previous experimental studies. The temperature and velocity profiles are represented under a wide range of RF power and for different sheath gas flow rates. With increasing power, the radial peak temperature typically shifts towards the wall. The resistance of the torch rises whereas the inductance diminishes with increasing RF power. The overall dependency of the coupling efficiency to the RF power is also estimated. The stabilization of the plasma flow dependency to the sheath swirl flow was investigated. The incorporation of Helium (0.02%) into an Argon gas was established to minimize the energy lost in the sidewall. The number and spacing of induction coil numbers affects the temperature and flow field distribution. A valuable approach to designing and optimizing the induction plasma system is presented in the proposed study. The obtained results are fundamental to specify ICP torch design criteria needed for multi-material processing.

LED lighting still suffers from its thermal problem linked mainly to the increase in junction temperature. The situation becomes more and more aggravated when it comes to decorative lighting. Indeed, this type of lighting application sometimes requires that the heat sink of the LED lamp be integrated into a narrow space, such as false or sloped ceilings, which limits the transfer of heat to the outside. In this context, the current study reports a numerical analysis of natural convection heat transfer around rectangular heat sink for LEDs lighting applications. The radiator is put in an inclined cavity with an orientation angle varying from 0̊ to 60̊. The effects of the enclosure inclination and its length on thermal behavior, flow structure in the cavity as well as on optical properties of the light source were highlighted. The CFD simulation showed a significant effect on the heat transfer rate when varying the cavity length (presented as an aspect ratio A) and its orientation. A = 4 was determined as an optimal cavity aspect ratio, and it was found that higher orientations are more sensitive to the increase of the length of the cavity. For θ = 60̊, the luminous efficiency is ameliorated by about 10% when increasing the cavity length from one to four. Accordingly, we proposed correlations in simple form to predict the heat transfer rate for different configurations studied.