The Journal of Technological and Space Plasmas
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Frobenius-Perron Operator Approach to the Beam-Beam Interaction in Circular Colliders
Get PDFUnlike most publications devoted to the application of the self-consistent method of the nonlinear Vlasov-Poisson system to the study of beam-beam interaction, in this article an alternative strategy using the elegant approach of the Frobenius-Perron operator for symplectic twist maps has been developed. A detailed analysis of the establishment of an equilibrium density distribution in phase space, as well as the behavior of the perturbed distribution function with respect to the coherent stability of the two beams, has been carried out.
Using the Renormalization Group technique for the reduction of the Frobenius-Perron operator, the case where the unperturbed rotation frequency (unperturbed betatron tune) of the map is far from any structural resonance driven by the beam-beam kick perturbation has been analyzed in detail. It has been shown that up to second order in the beam-beam parameter, the renormalized map propagator with nonlinear stabilization describes a random walk of the angle variable, implying that there exists an equilibrium distribution function depending only on the action variable.
The linearized Frobenius-Perron operators for each beam imply a discrete form of the linearized Vlasov equations, which essentially comprises a new method for calculating coherent beam-beam instabilities using a matrix mapping technique. In the special case of an isolated coherent beam-beam resonance, a stability criterion for coherent beam-beam resonances has been found in closed form.
An intriguing particular concerning the effect of repeated beam-beam collisions on collider luminosity has been derived explicitly. An addition of luminosity per kick (small though, of the order of the beam-beam parameter) in the course of successive beam-beam collisions could be achieved.
Discharge structure of Ar/Cl2 inductively coupled plasma: A cyclic study of discharge conditions at fixed power
Get PDFDischarge structure refers to the morphology of different plasma quantities, such as electron temperature, reaction rate, plasma potential, mass flux, net charge and species density, which are determined by plasma transport mechanism and chemical processes. This morphology is rather difficult to refine in complex electronegative plasma for it is contained in a multiple-physics-field coupled system. Regarding this difficulty, the combination of self-consistent simulation, theory analysis and experimental diagnostic of this system is needed. In the scope of present article, the fluid simulation and analytic theory are utilized to investigate the Ar/Cl2 inductively coupled plasma, via a cyclic tuning of discharge pressure and feedstock gas content parameters at fixing the power. Classic discharge structure, e.g., delta, parabola, flat-top, and hollow, and specific discharge mechanisms. e.g., self-coagulation, physics coagulation, de-coagulation, grouping behavior, and the ambi-polar diffusion of mediately electronegative plasma that is tolerant to the self-coagulation, are revealed. Besides, the two types of discharge stratification, i.e., space and species, are presented. Many non-neutralities are generated during the transport process of electronegative plasma when it gives rise to the discharge structure, which are summed and analyzed for better understanding the electronegative plasmas.
H-driven degradation of PFAS in the gas/liquid interface using electrochemistry configuration of cold plasma
Get PDFPlasma water treatment has emerged as a powerful technology capable of abate perfluoroalkyl substances (PFAS) in water matrices. With the electrochemical configuration and cathodic polarity, the electrified plasma/liquid interface (EPLI) not only produces in-situ hydrated electrons ( ) that readily react with PFAS, but also produced radicals in the plasma effluent. This study uses chemical reaction networks (CRN) to investigate the chemical pathways of PFAS degradation by EPLI-induced , allowing for a direct comparison with the bench experiments of Stratton et al. (Environ. Sci. Technol. 2017, 51, 3, 1643) and Alam et al. (Chemical Engineering Journal, 2024, 489, 151349). The computational results indicate that Perfluorooctanoic Acid (PFOA) degradation by EPLI-induced has a Faradaic efficiency of less than 0.01% given the typically low concentration of PFOA in water matrices, meaning that the majority of engages with water reduction, generating gaseous hydrogen. EPLI-induced alone cannot account for the energy efficiency observed in bench experiment of Stratton et al. and Alam et al., suggesting the presence of other plasma-induced radicals. This work evaluates the gas-phase H radical as crucial for degrading PFOA at the gas/liquid interface, which is created by the plasma effluent in contact with the water matrix. This work paves the way for construct effective plasma-based industrial reactors to degrade PFAS, suggesting the formation of radical-H in the plasma effluent as a key parameter to be optimized
Optimization of Argon Plasma Working Pressure through Parallel PIC Simulations for Enhancement of Material Surface Treatment
Get PDFIn this study, a novel method for simulating plasma dynamics using parallel programming has been developed. The equations based on Particle-in-Cell (PIC) method were utilized and adapted for this purpose. We utilized 35 processors from Sharif High Performance Computing (HPC) center and divided the plasma volume into 35 parts, with each part\u27s PIC equation solved on a separate processor. Once the computations were completed, the results from all processors were combined to form a complete plasma volume. The simulations revealed that there is an optimal pressure for argon, at which the ion flux onto the electrode surface is maximized. Increasing the absolute value of the electrode potential also increases this flux. Therefore, for a given potential, selecting the optimal pressure is crucial for the most effective surface modification using argon plasma. In this work, for applied voltage of -500 V, the optimum pressure was 100 mTorr
Environmentally Friendly Sterilization and Enhancement of Cellulose Using RF Plasma Process
Get PDFCellulose-based materials are widely used in wound care due to their biocompatibility, biodegradability, and fluid-handling capacity. While chemical functionalisation is commonly employed to impart antimicrobial activity, the role of physical surface modification in regulating bacterial adhesion remains less explored. In this study, low-pressure radiofrequency (RF) oxygen plasma was used as a dry and environmentally friendly approach to modify the surface of medical-grade cellulose without altering its bulk properties. Plasma treatment was performed in both glow and afterglow regions, enabling controlled exposure to reactive oxygen species. Surface modification resulted in pronounced nanoscale roughening and fissured topography of cellulose microfibers, as observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Plasma-induced oxidation of the cellulose surface, characterised previously by X-ray photoelectron spectroscopy (XPS), accompanied the morphological changes. Bacterial adhesion experiments using a non-pathogenic Escherichia coli model strain revealed significantly enhanced bacterial attachment on plasma-treated cellulose compared to untreated controls, with the strongest effect observed for glow-region treatments. The increased adhesion is attributed to the combined effects of surface roughness amplification and plasma-induced chemical functionalisation, which together increase the effective contact area between bacteria and the substrate. Rather than aiming to inhibit bacterial attachment, this work explores a physico-mechanical design concept in which surface topography is intentionally modified to favour bacterial binding to the dressing material itself. The observed behaviour is interpreted qualitatively using concepts from membrane mechanics as a phenomenological framework, without invoking a quantitative predictive model. While the present study does not assess net bacterial load reduction in wound environments, it establishes a materials-level basis for a “capture-and-remove” hypothesis, whereby preferential bacterial adhesion to a removable dressing could contribute to microbial load management during dressing changes. These findings highlight the potential of plasma surface engineering as a versatile tool for tailoring the biointerface of cellulose-based biomedical materials
Letter: Influence of inhomogeneous electrode biasing on the plasma parameters of inverted H2 fireballs
Get PDFIn this letter we present measurements of the influence on inhomogeneous electrode biasing on the basic plasma parameters of inverted fireballs in a hydrogen plasma. The measurements were performed in hydrogen because it is often used in many reactive plasmas, which are very important for technical or industrial applications. The dependence of the plasma parameters on voltages and currents on the electrodes are described in this work. It will be shown that the density profiles and the plasma potentials inside an inverted fireball can be shaped to a certain extend by asymmetric potentials on the anode
Experimental Investigation on Compact Current Non Thermal Plasma Assisted Hydrocarbon Reforming Hydrogen Rich Gas
Get PDFOn-board vehicle hydrogen-rich gas extraction of gasoline reforming utilizing for fuel cells and GDI-engine lean burn combustion enhancement NOx trap applications. A non-thermal plasma discharge electrode that produces a reduce current, increased voltage 15kV source arc plasma fuel reformer is designed to operate at an arc frequency of 50 Hz. The operating factors gasoline equivalence ratio between 4 and 6.and electronically control by the fuel injector and eliminating ground spark plug plasma arc generation. The plasma arc non-thermal reformer gasoline converted into gas that contains partial oxidation contains combustible gases like hydrogen (H2), CO, non-combustible gases like CO2, N2, and a small quantity of H2O. The nonthermal plasma technology alternative for on-board hydrogen vehicle applications
Technical Report: The Polomac approach to fusion energy
Get PDFDeutelio is a private initiative promoting an alternative path to fusion energy. The Tokamak research line pursued worldwide since 1970 met several difficulties, heavily jeopardising the objective of commercial energy production from fusion before 2050, as a support to the global effort towards Net Zero Emissions. As a result, new plasma magnetic confinement concepts, such as Stellarators or overlooked alternatives like the poloidal confinement are being pursued to achieve more efficiency and better performance.
The Polomac is a poloidal magnetic configuration where the outboard magnetic lines are deviated aside together with the plasma, to open some accesses to the dipole coils located inside the plasma. These accesses, called magnetic tunnels, are used to support, feed and cool the dipole coil. They avoid the impact with plasma which led to abandon past poloidal experiments, despite their good stability and confinement efficiency.
The poloidal confinement can achieve Deuterium-Tritium reactor conditions with a magnetic field 3 times weaker than the Tokamak, in steady state rather than pulsed. With the same high field as in the Tokamak the poloidal confinement can achieve Deuterium-Deuterium reaction, thus avoiding the development of the breeding blanket to produce the Tritium.
This paper presents the Polomac system, explains the development strategy of Deutelio through a small prototype focused to tune and assess the magnetic tunnels, and describes the possibility of deuterium-deuterium reaction
Nonlinear Cnoidal Waves and Formation of Patterns and Coherent Structures in Intense Charged Particle Beams
Get PDFThe longitudinal dynamics of an intense high energy beam moving in a resonator cavity has been studied in some detail. Through the method of separation of variables and its obvious straightforward generalization, a solution of the Vlasov equation for the distribution function of an intense charged particle beam in the longitudinal direction has been obtained. The thus found Bernstein-Greene-Kruskal (BGK) equilibrium has been utilized to construct stationary wave patterns in the special case when the velocity distribution (energy error distribution) is Maxwellian. These are cnoidal wave patterns, showing rather intriguing and in a sense unexpected analogy between the equilibrium wave patterns in an intense charged particle beam and similar wave clusters originally observed in shallow water.
Based on the hydrodynamic model, fully equivalent to the coupled nonlinear system of the Vlasov equation for the distribution function of an intense beam in the longitudinal direction and the equation for the resonator cavity potential, an amplitude equation in the most general form has been derived. A very interesting and important property of the nonlinear amplitude equation is the fact that it is of hyperbolic type (nonlinear wave equation with complex coefficients) in the entire interval of admissible values for the wave number except for a single critical point, in which it is of parabolic type (non-linear Schrodinger equation with complex coefficients).
First optimization steps for the Nanocluster Synthesis of Platinum-Yttrium Alloys: Insights from a sputter gas aggregation source
Get PDFNanoclusters (NCs) are critical in advanced technologies due to their unique size-dependent properties, offering significant potential in catalysis, energy storage, energy conversion and electronic devices. In this study, the first steps were taken towards optimizing the synthesis of nanoclusters from platinum-yttrium alloys for cost-efficient fuel cell technologies, employing a magnetron sputtering system combined with a gas aggregation source. Copper was used as a benchmark material to investigate the effects of varying gas flow rates, aggregation lengths, and coating times on cluster size. Subsequently, experiments with yttrium and platinum were conducted. NC sizes in the range of 4 to 12 nm could be synthesized. These results provide a comprehensive parameter map for NC synthesis and contribute to the further development of this kind of synthesis for sustainable fuel cell technology by reducing platinum consumption and improving catalytic efficiency