Plasma Formation Research Articles

Design and optimization analysis of key parameters for a compact ion source for BNCT

The 2.45 GHz Electron Cyclotron Resonance Ion Source (ECRIS) is widely recognized as an effective device for producing high-intensity H+, H2 +, and H3 + beams. In medical cyclotron applications, ion sources are required to be compact and highly adjustable. A compact design not only reduces the equipment size, facilitating integration and installation, but also enhances system stability and reliability. High precision in adjustment ensures the quality and stability of the ion beam, meeting the stringent requirements of medical treatments. Therefore, designing a high-performance compact ECR ion source is crucial for improving the performance and efficiency of medical cyclotrons. In this study, we designed an ECR ion source with a discharge chamber radius of only 25 mm and investigated its plasma formation using a three-dimensional model. We explored the effects of different microwave window positions on the extracted beam current, calculated, and determined the optimal position. Additionally, we studied the variations in the fractions of H+, H2 +, and H3 + ions in the chamber with respect to pressure and microwave power, and discussed the plasma processes within the ECR ion source chamber based on these findings.

High-order harmonic generation in boron carbide laser-induced plasma: comparison with carbon and boron plasmas, two-color-pumping-induced enhancement, quasi-phase-matching, and tuning of harmonics

The study of the laser-induced molecular plasma produced during the ablation of boron carbide as a medium for high-order harmonic generation is reported. The efficiency of harmonics generation in this laser-induced plasma is compared with the plasma produced on the surfaces of boron and carbon targets at the intensities of heating and driving pulses of 2 × 1010 and 3 × 1014 W/cm2, respectively. The stability of harmonic emission from boron carbide plasma was notably better compared with the boron and carbon plasmas. The influence of laser-induced plasma formation, the role of ablated components, the delay between heating and driving pulses, and the characteristics of converting pulses on the harmonic efficiency and harmonic cut-off in boron carbide plasma are studied.

CHANGES IN THE INDICATORS OF THROMBUS FORMATION AND FIBRINOLYSIS IN THE PATHOGENESIS OF CEPHALOHEMATOMA IN NEWBORNS

Background. Long-term resorption of cephalohematoma may be accompanied by the formation of surgical complications. The rate of resorption of cephalohematoma has uncertain dynamics and may depend on the characteristics of hemostasis in newborns.Aim. To define the level of thrombus formation and fibrinolysis in venous blood plasma in newborns with cephalohematomas.Methods. There were 90 newborns under observation, 30 – with medium and large-sized cephalohematomas (the cephalohematoma was punctured), 30 – with small-sized cephalohematomas (the cephalohematoma was not punctured). The control group – 30 healthy newborns. The level of thrombosis and fibrinolysis indicators was determined by flow cytometry on a Cytoflex LX device using multiplex analysis kits. Results. On the 10th day, the level of prothrombin in newborns of the first group was 1,33 times higher than in the control group, and 1,47 times higher than in the second group of the study. On the 10th day, the concentration of antithrombin III in the first and second groups exceeded the control group by 5.28 and 8,82 times, and on the 28th day of the study by 6,9 and 7,.28 times. The concentration of type 1 plasminogen activation inhibitor in the first and second groups was higher than in the control group by 3,11 and 5,25 times on the 10th day, and on the 28th day of the study by 2,88 and 3,93 times. The level of D-dimer on the 10th day in the first and second groups was 1,43 and 1,71 times higher, and on the 28th day in both groups it was 1,6 times higher than the control group.Conclusion. Reparation for cephalohematomas is associated with mechanisms of resorption of subperiosteal hemorrhage and depends on the fibrinolytic activity of the hemostatic system. It is likely that the isolation of the cephalohematoma from the systemic circulation under conditions of inhibition of plasminogen activity may be the cause of long-term persistence of subperiosteal hemorrhage.

Influence of species kinetics on discharge characteristics in oxygen helicon plasma

Abstract Oxygen (O2) helicon plasmas in multiple wave modes were excited by a right-helical antenna with an upper metal endplate at low pressure. Mode transitions were observed at increasing input power or magnetic field, characterized by obvious jumps of plasma parameters. Blue Core appears at high magnetic fields (~700 G) and input powers (~1700 W), with a large radial gradient of plasma density, ion line intensity, and electron temperature. Emission spectra demonstrate that the blue lights originate from O II lines. We found that the intensity ratio of O II to O I of Blue Core in O2 is lower by one order than that in N2 or Ar despite their similar ionization rates and plasma densities in Blue Core area. A high-temperature B-dot probe together with a waveform fitting procedure was used to present the measured oscillating waveforms of m =+1 helicon waves, showing distinct wave structures of different eigenmodes. Cavity mode resonance is suggested to be responsible for the formation of standing waves of discrete eigenmodes. A pressure balance model was developed to estimate the species densities around the central area in different modes, showing massive dissociation of O2 molecules and high density of O atoms locally, so that O2 helicon plasma behaves a species feature of monatomic gas discharge. The obviously low intensity of O II lines compared to O I lines of Blue Core in O2 is related to the quite high excitation threshold of O+ ions (~30 eV) although electron density and temperature are relatively high. The combined effects of dispersed reaction energy distribution, massive molecule dissociation and negative ion creation are considered to be the main causes for requirement of much higher RF power and magnetic field for Blue Core formation in O2 helicon plasma than that in Ar. The calculated radial profile of power deposition and the captured plasma morphology confirm that the dominant central electron heating is the essential reason for the large radial gradients of plasma density and electron temperature which contributes to the serious neutral depletion and Blue Core formation.

GGR Handbook of Rock and Mineral Analysis Chapter 5 The Inductively Coupled Plasma

This chapter (The Inductively Coupled Plasma) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of A Handbook of Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).Chapter 5 (from Section 1 of the handbook dealing with fundamentals of measurement and instrument design) is a comprehensive treatment of the inductively coupled plasma – a significant cornerstone of modern geoanalytical spectrometry. The Chapter includes discussion of plasma formation and key components of the ICP source. This is followed by an examination of the challenges of sample introduction into the plasma, particularly focussed on the introduction of liquid samples. The physical structure of the plasma, its robustness and interference effects are fully examined prior to a section dealing with how the operation of plasma is optimised in practise.

A mechanistic model of in vitro plasma activation to evaluate therapeutic kallikrein-kinin system inhibitors.

The kallikrein-kinin system (KKS) is a complex biochemical pathway that plays a crucial role in regulating several physiological processes, including inflammation, coagulation, and blood pressure. Dysregulation of the KKS has been associated with several pathological conditions such as hereditary angioedema (HAE), hypertension, and stroke. Developing an accurate quantitative model of the KKS may provide a better understanding of its role in health and disease and facilitate the rapid and targeted development of effective therapies for KKS-related disorders. Here, we present a novel, detailed mechanistic model of the plasma KKS, elucidating the processes of Factor XII (FXII) activation, the kallikrein feedback loop, cleavage of high molecular weight kininogen leading to bradykinin (BK) production, and the impact of inhibitors. The model incorporates both surface and solution-phase reactions of all proteins in the KKS, describing how binding site concentration affects the rate of surface reactions. The model was calibrated and validated using a variety of published and in-house experimental datasets, which encompass a range of dextran sulphate (DXS) concentrations to initiate contact activation and various KKS inhibitors to block bradykinin production. Our mathematical model showed that a trace amount of activated FXII is required for subsequent FXII activation. The model also reveals a bell-shaped curve relationship between the activation of the KKS and the number of DXS surface binding sites. Simulations of BK generation in healthy and HAE plasma demonstrated the impact of C1 esterase inhibitor (C1inh) deficiency via increased peak BK levels and accelerated formation in HAE plasma. The efficacy of KKS inhibitors, such as CSL312, ecallantide, and C1inh, was also evaluated, with CSL312 showing the most potent inhibition of BK generation. The present model represents a valuable framework for studying the intricate interactions within the plasma KKS and provides a better understanding of the mechanism of action of various KKS-targeted therapies.

Plasma formation during flash sintering of boron carbide – Part II: Effect on sintering and optimisation of process variables

Field assisted sintering techniques, such as Flash Sintering (FS), allow rapid heating and densification of ceramics within seconds at significantly reduced environmental temperatures. FS of oxides has been extensively researched since 2010, whereas the potential densification of non-oxides such as carbides is rarely investigated. In the first part of this investigation the atmospheric breakdown and plasma formation under FS-conditions relevant to SiC and B4C was researched. In the present work, the FS of B4C was investigated with and without plasma formation for comparison, and the influence and optimum combination of the other main FS-parameters determined. The results showed that at a furnace temperature of 1500 °C, it is possible to densify B4C by DC FS with or without an initial plasma formation. However, though plasma formation did not itself lead to densification of the material, the plasma-induced removal of the B2O3-layer on the surface of the powder led to a significant improvement in subsequent densification during FS. The effect of the Ar-plasma generated in removing the surface oxide from B4C-particles was confirmed by SEM and XPS. Other process variables such as carbon additives, thermal insulation and hold time also significantly influenced the densification of B4C by FS. With the optimised conditions, 96 % dense B4C, with a grain size of 10 μm and a hardness of 31 GPa (HV1) was produced by pressureless FS in 5 min at a furnace temperature of 1500 °C.

Wave steepening and shock formation in ultracold neutral plasmas

We present observations of wave steepening and signatures of shock formation during expansion of ultracold neutral plasmas formed with an initial density distribution that is centrally peaked and decays exponentially with distance. The plasma acceleration and velocity decrease at large distance from the plasma center, leading to central ions overtaking ions in the outer regions and the development of a steepening front that is narrow compared to the size of the plasma. The density and velocity change dramatically across the front, and significant heating of the ions is observed in the region of steepest gradients. For a reasonable estimate of electron temperature, the relative velocity of ions on either side of the front modestly exceeds the local sound speed (Mach number M≳1). This indicates that by sculpting steep density gradients, it is possible to create the conditions for shock formation, or very close to it, opening a new avenue of research for ultracold neutral plasmas.

Coriolis forces modify magnetostatic ponderomotive potentials

It is possible to produce a ponderomotive effect in a plasma system without time-varying fields, if the plasma flows over spatial oscillations in the field. This can be achieved by superimposing a spatially oscillatory perturbation on a guide field, then setting up an electric field perpendicular to the guide field to drive flow over the perturbation. However, subtle distinctions in the structure of the resulting electric field can entirely change the behavior of the resulting ponderomotive force. Previous work has shown that, in slab models, these distinctions can be explained in terms of the polarization of the effective wave that appears in the co-moving frame. Here, we consider what happens to this picture in a cylindrical system, where the transformation to the co-moving (rotating) frame is not inertial. It turns out that the non-inertial nature of this frame transformation can lead to counterintuitive behavior, partly due to the appearance of parallel (magnetic-field-aligned) electric fields in the rotating frame even in cases where none existed in the laboratory frame. Apart from the academic interest of this study, the practical impact lies in being better able to anticipate the antenna configuration on the plasma periphery of a cylindrical plasma that will lead to optimal ponderomotive barrier formation in the interior plasma.

Ultrafast imaging of laser-induced modifications in planar targets via single-shot in-line holography

Abstract We present a holographic single-shot coherent diffractive imaging method based on in-line holography that allows the ultrafast characterization of 2D transmission maps of semi-transparent planar targets such as foils in amplitude and phase. Holographic information is obtained from the interference of the transmitted primary beam with the fields scattered from the modified or unknown target regions. A specialized iterative phase retrieval is used to incorporate the holographic nature of the approach and to accelerate and improve convergence. The achievable quality and reproducibility of the reconstructed transmission maps as well as optimal setup parameters are investigated using realistic pre-characterized reference targets. We used non-circular laser-induced hole structures in 30 nm thin gold foils that represent the final state of a laser modification and show that the far field error of the reconstructed diffraction images can be used to estimate and optimize the reconstruction quality in the object plane in order to obtain accurate and reproducible transmission maps. Our results mark the important first step towards the full spatio-temporal analysis of all stages of laser material modification or laser ablation in two-color pump probe experiments, including plasma formation, equilibration, and expansion.

Innovative approaches in the food industry: Microwave plasma technology and applicability in foods

In this study, the use of microwave technique, which is becoming increasingly widespread in the food sector, and the advantages of microwave plasma technology, which has not yet been used much in the food sector, and the production of microwave plasma assembly in laboratory size. In food technology, plasma can be applied hot and cold. Inert gases are used in plasma formation and low-level microwave energy is also used. Additionally, the use of oxygen gas in the current system increases oxidative stress on microorganisms found in foods. Since plasma formation occurs under strong vacuum, it also effectively provides microbial inactivation in food systems. Cold and low-pressure plasma technology has emerged as a promising and innovative method for the microbial inactivation on dry food surfaces. Therefore, microwave plasma system has an important potential to use in many food systems such as spices, dried fruits and vegetables. In this context, the microwave plasma setup was created by us in this study. A strong vacuum system is required for the formation of microwave plasma. In addition, it has been determined that the application time is very important for the application of microwave plasma in foods and that there are structural deterioration in foods over a certain period of time. As a result, it is understood that food poisoning can be prevented by using microwave plasma in foods, and this will contribute to extending the shelf life of foods, and therefore the technique needs to be further investigated and considered in food applications.

Exploring formation of Quark-Gluon Plasma through two-particle correlations functions in A+A and p+p data

This paper is the result of team’s hard work, which delves into the correlation functions in proton-proton and PbPb(Lead-Lead) collisions, scrutinizing their relevance in the formation of quark-gluon plasma. This project first simulated these high-energy collisions and generated a comprehensive dataset of proton-proton and PbPb(Proton-Proton) interactions. The entire analysis is designed around the task of calculating azimuthal and pseudorapidity correlation functions, and wish to compare the differences and similarities between the two collision types. Also delved into these correlation functions in proton-proton collisions as potential evidence for QGP(Quark-gluon plasma), a type of matter typically found in heavy metal collisions such as Pb-Pb. The results reveal unique patterns lurking in the correlation functions that suggest that QGPs may form even in smaller collision systems. Also Quark-Gluon Plasma (QGP) is a state where quarks and gluons move freely at extremely high energy densities. The two-particle correlation function helps identify QGP by measuring how particles are correlated after a collision. Specific patterns in these correlations, like a “ridge” structure, indicate the collective behavior of particles, signaling the formation of QGP. These findings are expected to shed more light on the intricate dynamics in particle collisions and the specific conditions that lead to the formation of QGPs.

Spectral analysis of high-order harmonic generation in carbon plasma using linearly, radially, and azimuthally polarized femtosecond pulses

We demonstrate high-order harmonic generation in carbon plasma using linearly, radially, and azimuthally polarized beams from a femtosecond laser (1030 nm, 40 fs, 50 kHz). The conditions for carbon plasma formation during laser ablation were optimized by adjusting the heating pulse energy in the cases of the single-color (1030 nm) and two-color (1030 nm + 515 nm) pump schemes to generate harmonics up to the 39th order. The application of radial and azimuthally polarized annular single-color (1030 nm) beams at optimal conditions of plasma formation allowed the demonstration of the spectral division and inclination of the vector harmonics. An asymmetric distribution of harmonics was obtained using the vortex beam generated during the propagation of laser radiation through the quarter-wave plate and S-waveplate.

Investigation of non-equilibrium phenomena in nitrogen RF inductively coupled plasma discharges: a state-to-state approach

Abstract This work presents a vibrational and electronic (vibronic) state-to-state (StS) model for nitrogen plasmas implemented within a multi-physics modular computational framework to study non-equilibrium effects in inductively coupled plasma (ICP) discharges. The vibronic master equations are solved in a tightly coupled fashion with the flow governing equations eliminating the need for invoking any simplifying assumptions when computing the state of the plasma, leading to a high-fidelity physical modeling. The model’s computational complexity is reduced via a maximum entropy coarse-graining approach, verified through zero-dimensional isochoric calculations. The coarse-grained StS model is employed to study the plasma discharge in the ICP facility at the von Karman Institute for Fluid Dynamics, Belgium. Results reveal pronounced discrepancies between StS predictions and those obtained based on local thermodynamic equilibrium (LTE) models, which are conventionally used in the simulation of such facilities. The analysis demonstrates a substantial departure of the internal state populations of atoms and molecules from the Boltzmann distribution. This has significant implications for energy coupling dynamics, affecting the discharge morphology. Further analysis reveals a quasi-steady-state population distribution in the plasma core, allowing for the construction of an efficient and ‘self-consistent’ macroscopic two-temperature (2T) formulation. Non-LTE simulations indicate significant disparities between the StS model and the commonly used Park 2T model, whereas the newly proposed 2T model aligns closely with StS simulations, capturing key features of non-equilibrium plasma formation. In particular, the current study highlights the importance of the vibrational-translational energy transfer term in shaping the plasma core morphology, suggesting a notable sensitivity to heavy-impact vibrational excitations and dissociative processes.

Electromagnetic plasma micro actuator for active airflow control

This study presents a novel electromagnetic plasma micro actuator capable of generating ionic wind at an extremely low voltage. Ionic and electron movements, driven by the Lorentz force, introduce a lateral injection of initiation carriers, resulting in a significant reduction in discharge onset voltage. Straight ionic wind was demonstrated using a tapered gap electrode, which allowed continuous movement of plasma filament along the electrode at the speed of 4 m/s when a DC pulse of 900 V was applied. The results suggest that the proposed device may address key challenges faced by current ionic wind generators, such as high voltage requirements and limited device lifespans. In addition, a notable change in the airflow was observed when the direction of ionic wind was altered, indicating the feasibility of active airflow control with stable plasma formation and fast response times.

Phthalate monoesters affect membrane fluidity and cell-cell contacts in endometrial stromal adherent cell lines and spheroids

Phthalate monoesters have been identified as endocrine disruptors in a variety of models, yet understanding of their exact mechanisms of action and molecular targets in cells remains incomplete. Here, we set to determine whether epidemiologically relevant mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) can affect biological processes by altering cell plasma membrane fluidity or formation of cell-cell contacts. As a model system, we chose endometrial stromal cell lines, one of which was previously used in a transcriptomic study with MEHHP or MEHHP-containing mixtures. A short-term exposure (1 h) of membrane preparations to endocrine disruptors was sufficient to induce changes in membrane fluidity/rigidity, whereas different mixtures showed different effects at various depths of the bilayer. A longer exposure (96 h) affected the ability of cells to form spheroids and highlighted issues with membrane integrity in loosely assembled spheroids. Finally, in spheroids assembled from T-HESC cells, MEHHP interfered with the formation of cell-cell contacts as indicated by the immunostaining of zonula occludens 1 protein. Overall, this study emphasized the need to consider plasma membrane, membrane-bound organelles, and secretory vesicles as possible biological targets of endocrine disruptors and offered an explanation for a multitude of endocrine disruptor roles documented earlier.

Enhanced DC surface discharge characteristics of epoxy composites treated by dielectric barrier discharge plasma fluorination and its mechanisms

Surface flashover is a destructive high-voltage discharge phenomenon greatly limiting the update of modern power electronic and electrical equipment. Surface plasma treatment is a high-energy, eco-friendly, and convenience method, it changes the surface properties and owns potential to improve flashover voltage. In the present work, plasma fluorination (PF) technique are used to treat EP/Al2O3 composites, surface morphology, element and bonds content, surface trap, conductivity, charging, and DC flashover voltage are tested and simulated, the effects of plasma on surface discharge are explained through the investigation from microscopic molecular reactions to macroscopic flashover characteristics. It indicates the 20 min PF modified sample exhibits the superior DC flashover performance, increasing by 17 % compare to untreated sample. During PF modification, the epoxy chains are degraded and fluorinated, the degradation rather than fluorination of molecular chains introduce large amounts of shallow traps into the composites, accelerating carriers’ migration and improving surface conductivity, causing surface charges to dissipate through surface conductance. Consequently, the surface electric field distortion degree reduces, and the subsequent gas ionization and plasma formation in the gas phase is suppressed, leading to the improvement of DC flashover voltage after PF modifications.

Model of astrophysical jets in magnetic fields of laser relativistic plasmas

A brief review of the results of experimental modeling of cosmic jets in superstrong magnetic fields of laser relativistic plasma is given. It is noted that the development of cyclotron instability with the generation of cyclotron radiation plays a key role in a number of processes in a plasma with a magnetic field — self-localization of plasma in the form of solitons, conversion of rotational motion of plasma into translational motion, cyclotron acceleration of charged particles, separation (stratification) of a plasma jet into separate plasma formations.

ТЕОРЕТИЧНЕ ДОСЛІДЖЕННЯ ТЕПЛОВИХ ПРОЦЕСІВ НА ВУГЛЕЦЕВИХ ЕЛЕКТРОДАХ В РЕЗУЛЬТАТІ ДІЇ ПЛАЗМИ ПРИ ГЕНЕРАЦІЇ НАНОСТРУКТУР У ВАКУУМНІЙ ДУЗІ

A mathematical model has been refined to determine the thermophysical and thermomechanical processes on electrodes during the plasma formation of nanostructures. The model takes into account the effects of electrode spots, evaporation, sputtering, and thermal stresses in the electrode bodies. Calculations of temperature distribution on the surfaces of the graphite cathode and anode were carried out, considering the conditions necessary for obtaining nanostructures. An analysis of the thermophysical processes on the surfaces of the graphite cathode and anode during the transition to the working regime was conducted. The stability of the electrodes during plasma generation of nanostructures was determined by changes in the geometry of the electrodes. Calculations of the temperature fields on the end surface of the graphite cathode showed that with a continuous increase in the cathode surface temperature, the nature of its distribution does not change fundamentally. Calculation of temperature fields along the radius of the graphite cathode at different moments in time during the transition to the working regime showed a slight impact of evaporation on the change in the cathode's geometry. Determining the temperature fields along the generatrix of the anode showed the greatest impact of evaporation on the small area of the anode closest to the cathode. The dependencies of the acting stresses on temperature for the graphite cathode and anode were obtained. Studies of the dynamics of changes in thermal stresses on the electrodes during the formation of nanostructures in a plasma environment indicate that the values of thermal stresses are far from the material's strength limit. A theoretical study of the thermophysical and thermomechanical processes on the graphite cathode was carried out and compared with experimental measurements. The calculation of the electrodes' lifespan during the creation of carbon nanostructures in a plasma environment was 2.52∙105 s. The experimental lifespan of the graphite cathode is 2.88∙105 s, which is quite close to the calculated value. The coincidence of the obtained theoretical and experimental results indicates the viability of the developed model. The article may be of interest when designing equipment for obtaining nanostructures in a plasma environment and for further research on the physical parameters of electrodes.

Detached Plasma Studies in GOL-NB with Extra Gas Injection

The magnetic system of an open trap usually includes expansion sections located between highfield magnetic mirrors and end surfaces that receive plasma. In the GOL-NB device, an arc plasma gun is located in one of the expanders, which creates a low-temperature starting plasma in the confinement area. The parameters of the surface plasma sheath affect the electrical connection of the confinement area with the walls and, thereby, affect the contribution of the line-tying effect to the plasma stability and the longitudinal energy losses from the trap. The experiments with additional hydrogen injection into the plasma gun were carried out at GOL-NB. We observed a radiating plasma formation detached from the surface, which visually corresponds to that in radiating divertors in tokamaks. In both standard and detached modes, decaying plasma existed near the receiving electrodes during the entire observation time after the discharge current was terminated. In the central trap of GOL-NB, some structures in the Fourier spectrogram of magnetic fluctuations manifest earlier in the detachment mode than in the standard mode and have lower frequencies. We associate these structures with the onset of interchange-like modes due to the loss of plasma stabilization by the line-tying to the conducting ends. The observed plasma response to the additional gas supply confirmed our understanding of the line-tying effect as the main factor stabilizing the plasma core in the initial phase of density accumulation in the central trap.