Plasma Model Research Articles

Emicizumab-mediated hemostatic function assessed by thrombin generation assay in an in vitro model of factor VIII-depleted thrombophilia plasma.

Patients with hemophilia A (PwHA) may have concurrent deficiency of representative anticoagulant proteins, protein (P)C, PS, and antithrombin (AT), which reduces bleeding frequency. However, emicizumab-driven hemostasis in PwHA with such thrombophilic potential remains unclarified. This study investigated the influence of natural anticoagulants on emicizumab-driven coagulation in HA model plasma. Various concentrations of PS and AT were added to PS-deficient plasma and AT-deficient plasma in the presence of anti-FVIII antibody (FVIIIAb; 10BU/mL). PC-deficient plasma was mixed with normal plasma at various concentrations in the presence of FVIIIAb. Emicizumab (50µg/mL) was added to these thrombophilic HA model plasmas, prior to tissue factor/ellagic acid-triggered thrombin generation assays. Co-presence of emicizumab increased peak thrombin values (PeakTh) dependent on PS, AT, and PC concentrations. Maximum coagulation potentials in the PS-reduced HA model plasmas remained normal in the presence of emicizumab. PeakTh were close to normal in the presence of 50%AT irrespective of emicizumab, but were higher than normal in the presence of 25%AT. Addition of recombinant FVIIa (corresponding to an administered dose of 90μg/kg) enhanced coagulation potential to normal levels. Our findings provide novel information on hemostatic regulation in emicizumab-treated PwHA with a possible thrombophilic disposition.

Predictive modeling of the JET D–T plasma boundary

AbstractThe SOLPS‐ITER3.0.8 code with new Grad‐Zhdanov module was applied for predictive modeling of tritium plasma and deuterium‐tritium mixture in tokamak JET. The moderate power scenario of shot JPN #85278 modeled earlier for deuterium plasma was taken as a starting point. Effect of puffing increase, which was applied in experiment, on divertor conditions and inter‐ELM tungsten sputtering for both working gases and on isotope separation in their mixture is analyzed. Both for attached and for semi‐detached outer targets, the tritium plasma shows moderate increase in SOL width compared to deuterium one. The tungsten sputtering at the outer target in the inter‐ELM period for tritium is an order of magnitude bigger than that for deuterium. The D–T separation in the D–T mixture is moderate.

A Study of the Atomic Processes of Highly Charged Ions Embedded in Dense Plasma

The study of atomic spectroscopy and collision processes in a dense plasma environment has gained a considerable interest in the past few years due to its several applications in various branches of physics. The multiconfiguration Dirac-Fock (MCDF) method and relativistic configuration interaction (RCI) technique incorporating the uniform electron gas model (UEGM) and analytical plasma screening (APS) potentials have been employed for characterizing the interactions among the charged particles in plasma. The bound and continuum state wavefunctions are determined using the aforementioned potentials within a relativistic Dirac-Coulomb atomic structure framework. The present approach is applied for the calculation of electronic structures, radiative properties, electron impact excitation cross sections and photoionization cross sections of many electron systems confined in a plasma environment. The present study not only extends our knowledge of the plasma-screening effect but also opens the door for the modelling and diagnostics of astrophysical and laboratory plasmas.

Self-consistent model and numerical approach for laser-induced non-equilibrium plasma

This paper presents a self-consistent multi-dimensional mathematical model and a numerical approach for simulating the low-temperature plasma induced by the femtosecond laser filament. Addressing limitations in current models, we analyze key aspects of the laser plasma behavior, including plasma generation, detailed chemical kinetics, energy exchange channels, total energy balance, and hydrodynamics. The developed model and LOTASFOAM code are applied to study the temporal and spatial decay of the plasma produced by a femtosecond laser pulse in pure nitrogen at atmospheric pressure. The paper also includes a discussion on the spatial and temporal dynamics of electronically excited states of nitrogen in the decaying laser plasma.

The magnetised plasma Richtmyer–Meshkov instability: elastic collisions in an ion–electron multifluid plasma

The influence of an applied magnetic field on the collisional plasma Richtmyer–Meshkov instability (RMI) is investigated through numerical simulation. The instability is studied within the five-moment multifluid plasma model without any simplifying assumptions such as infinite speed of light, negligible electron inertia or quasineutrality. The plasma is composed of ion and electron fluids, and elastic collisions are modelled with the Braginskii transport coefficients. A collisional regime is investigated and the magnetic field is applied in the direction of shock propagation, which is perpendicular to the density interface. The primary instability is influenced by several terms affecting the evolution of circulation, the most significant of which are the baroclinic, magnetic field torque and intraspecies collisional terms. The applied magnetic field results in a reduction of interface perturbation growth, agreeing qualitatively with previous numerical simulations for the case of an ideal multifluid plasma RMI. The only major difference in the present case's instability mitigation by applied magnetic field, relative to the ideal case with applied magnetic field, is that the elastic collisions replace and obstruct the secondary vorticity suppression mechanism through collisional dissipation of vorticity. Additionally the collisions, influenced by the combination of self-generated and the applied magnetic field, introduce anisotropy to the problem. The primary suppression mechanism for the RMI is unchanged relative to the ideal case, i.e. the magnetic field torque resisting baroclinic deposition of vorticity in the ion fluid.

Kappa distribution from particle correlations in nonequilibrium, steady-state plasmas.

Kappa-distributed velocities in plasmas are common in a wide variety of settings, from low-density to high-density plasmas. To date, they have been found mainly in space plasmas, but are recently being considered also in the modeling of laboratory plasmas. Despite being routinely employed, the origin of the kappa distribution remains, to this day, unclear. For instance, deviations from the Maxwell-Boltzmann distribution are sometimes regarded as a signature of the nonadditivity of the thermodynamic entropy, although there are alternative frameworks such as superstatistics where such an assumption is not needed. In this work we recover the kappa distribution for particle velocities from the formalism of nonequilibrium steady-states, assuming only a single requirement on the dependence between the kinetic energy of a test particle and that of its immediate environment. Our results go beyond the standard derivation based on superstatistics, as we do not require any assumption about the existence of temperature or its statistical distribution, instead obtaining them from the requirement on kinetic energies. All of this suggests that this family of distributions may be more common than usually assumed, widening its domain of application in particular to the description of plasmas from fusion experiments. Furthermore, we show that a description of kappa-distributed plasma is simpler in terms of features of the superstatistical inverse temperature distribution rather than the traditional parameters κ and the thermal velocity v_{th}.

Evaluation of a Nondepleted Plasma Multiprotein-Based Model for Discriminating Psychiatric Disorders Using Multiple Reaction Monitoring-Mass Spectrometry: Proof-of-Concept Study.

Psychiatric evaluation relies on subjective symptoms and behavioral observation, which sometimes leads to misdiagnosis. Despite previous efforts to utilize plasma proteins as objective markers, the depletion method is time-consuming. Therefore, this study aimed to enhance previous quantification methods and construct objective discriminative models for major psychiatric disorders using nondepleted plasma. Multiple reaction monitoring-mass spectrometry (MRM-MS) assays for quantifying 453 peptides in nondepleted plasma from 132 individuals [35 major depressive disorder (MDD), 47 bipolar disorder (BD), 23 schizophrenia (SCZ) patients, and 27 healthy controls (HC)] were developed. Pairwise discriminative models for MDD, BD, and SCZ, and a discriminative model between patients and HC were constructed by machine learning approaches. In addition, the proteins from nondepleted plasma-based discriminative models were compared with previously developed depleted plasma-based discriminative models. Discriminative models for MDD versus BD, BD versus SCZ, MDD versus SCZ, and patients versus HC were constructed with 11 to 13 proteins and showed reasonable performances (AUROC = 0.890-0.955). Most of the shared proteins between nondepleted and depleted plasma models had consistent directions of expression levels and were associated with neural signaling, inflammatory, and lipid metabolism pathways. These results suggest that multiprotein markers from nondepleted plasma have a potential role in psychiatric evaluation.

An alternative method to mimic mode conversion for ion cyclotron resonance heating

Ion cyclotron range of frequency waves in hot plasmas exhibit spatial dispersion effects and the wave equation takes the integro-differential form. Under the local plasma model assumption, the wave equation can be simplified to the differential form and adapts to the numerical scheme of the finite element method (FEM). Even though direct absorption of fast waves by ions and electrons can be described well by the local plasma model, linear mode conversion associated with non-local effects is absent. To deal with this issue, an alternative method is put forward in this paper where quasi-electrostatic fluid waves based on the multi-fluid warm plasma model are employed to take the place of ion Bernstein waves in mode conversion. On this basis, an interative fluid-kinetics (INTFLUK) code based on the FEM is developed for full-wave simulation in hot plasmas. Derivation of the wave equations as well as benchmarking of the INTFLUK code against other wave simulation codes are carried out. In both one- and two-dimensional cases, the validity of the INTFLUK code was verified by comparison of the wave field distributions and power deposition. As a useful illustration of the INTFLUK code including the scrape-off layer and a realistic antenna, the influence of the poloidal antenna phasing difference on ion cyclotron resonance heating is analyzed. Finally, it should be noted that the method in this paper has the potential to be extended to the three-dimensional case, which will be considered in the near future.

Modelling the capacitance of the elongated plasma in tokamak

The capacitance model suitable for the non-circular cross-section plasma is studied based on the capacitance model of the circular cross-section plasma. The coaxial elliptic-torus capacitor property is further derived and used to determine the capacity of non-circular cross-section tokamak plasma, such as EAST (Experimental Advanced Superconducting Tokamak). By testing all the physical terms in this model, we find that the capacitance Cp\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Cp$$\\end{document}) is increasing exponentially with the increase of elongation ratio (k2/k1), while the minor radius ratio (a2/a1) is just reversed at the flat-top of plasma current, and the capacitance property is implicitly included in the H-mode study during the L–H transition. It is noted that Cp-H mode is the least and Cp-I mode is approximately equal to Cp-L mode under the L-mode, I-mode and H-mode regimes based on this capacitance model in EAST. Consequently, it may be integrated into an equivalent circuit of the tokamak transformer or transport computer code of the edge plasma for use in precise simulations of fusion plasma behavior in the future, such as ITER (International Tokamak Experimental Reactor) or BEST (Burning-plasma Experimental Superconducting Tokamak) in China.

In situ measurement of the electron elastic reflection coefficient at a plasma-exposed silicon dioxide surface

Plasma simulations require accurate input data that describe the interactions of electrons with plasma-exposed surfaces. One important, rarely studied interaction is elastic reflection. This article presents measurements of the elastic reflection coefficient made in situ, i.e. during plasma exposure, in an inductively coupled plasma (icp) reactor that has an azimuthally asymmetric, rf-biased substrate electrode. The rf current and voltage across the sheath adjacent to this electrode were measured, along with the ion current density and electron temperature, for argon plasmas at 0.67 and 1.33 Pa. Using the measurements and a numerical sheath model, the currents contributed by electrons that are emitted from the rf-biased electrode are determined. Some emitted electrons are elastically reflected from the opposing surface, the fused quartz window below the icp source. Deflection of these electrons by 13.56 MHz electric and magnetic fields in the plasma can prevent them from returning to the rf-biased electrode, producing a second-harmonic current at 27.12 MHz. The transport of the emitted electrons is simulated by a plasma model that includes electric and magnetic effects, transit-time effects, elastic reflection at the electrode as well as the window, and multiple passes through the plasma. From the plasma model and the measured 27.12 MHz current, the elastic reflection coefficient at the quartz window was determined, for electron energies from 25 eV to 1.2 keV. The measured reflection coefficient was higher than literature values for clean Si, but it had a similar energy-dependence. An approximate analytical form for its energy-dependence is presented, as well as an uncertainty analysis.

RAM‐SCB Runs on Request at CCMC

AbstractThe Ring current–Atmosphere interactions Model (RAM) with Self‐Consistent magnetic (B) field (SCB) combines a large‐scale kinetic model of ring current plasma with a three‐dimensional (3‐D) force‐balanced model of the terrestrial magnetic field. RAM‐SCB simulates the evolution of major ion species (H+, O+, and He+ by default) and electrons as a function of azimuth, radial distance, energy, and pitch angle. Simulation outputs include the Dst index, and pressure and differential flux of the modeled species, thus providing benefit as a science code and to inform surface charging hazard within the model domain. Version 2.2 of this open‐source simulation code has now—as of 8 August 2023—been made available for Runs‐On‐Request via the Community Coordinated Modeling Center.

A Machine Learning Approach to Identify Individualized Baseline MRI, Plasma, Cardiovascular and Lifestyle Predictors of a 5‐Year Cognitive Decline

AbstractBackgroundThe mapping between risk factors and biomarkers with cognitive performance and decline in the older adults is complex and varies significantly across different age and sex groups. Our goals were to (i) develop a machine learning (ML) model to predict baseline cognition and cognitive decline over a 5‐year follow‐up using only baseline assessments, and (ii) identify important modifiable and non‐modifiable predictors of cognitive decline across different age strata.MethodWe utilized longitudinal data from 2219 participants (mean age (SD): 70 (12) years, 49% male) from Mayo Clinic Study of Aging who had 43 features belonging to cardiovascular health, plasma, MRI (diffusion and structural), and lifestyle measures. Cognition was measured using a global cognition z‐score. We built ML models to predict baseline cognition and rate of cognitive decline over 5‐years (linear regression slopes over all individual followup measurements for each participant) using baseline assessments as inputs. We then built a model for each category separately and as a pooled model with all measures included, incorporating education and sex as demographic features in all models (Fig. 1). We applied a multi‐layer stack ensemble ML technique that utilized repeated k‐fold bagging to maximize accuracy. Importance of the top predictors were assessed in three age strata (55‐65 years (31%), 65‐80 years (46%), 80‐95 years (23%)).ResultThe pooled model explained the largest variance for prediction of baseline cognition and cognitive decline (Fig. 2). In individuals ≤80 years, lower NfL was most predictive of higher baseline cognition. A combination of imaging and plasma features predicted the 5‐year cognitive decline. Additionally, in individuals ≤65 years, diabetes and hypertension were important predictors of faster cognitive decline and in those >80, lower BMI and midlife physical/cognitive activity was an important predictor of faster cognitive decline (Fig. 3).ConclusionThe plasma model was best for baseline cognition prediction and imaging model was best for cognitive decline prediction. There was significant heterogeneity in important features across the age strata. In individuals >65 years, plasma GFAP was the most important predictor of cognitive decline. Our model allowed identification of key risk factors that predicted cognitive decline.

Low-Energy Electron Scattering from Pyrrole and Its Isomers.

Low-energy electron scattering from pyrrole and its isomers, such as 2-H pyrrole, cyclopropanecarbonitrile, and Z-2 butenenitrile, is explored in detail in this article. The electron interaction with the target molecules was studied through R-matrix theory. We have used minimal STO-3G and advanced DZP basis sets on a fine energy grid from 0.1 to 12 eV electron energy in the calculation. The properties of the STO-3G and DZP-based targets, such as their ionization energy, polarizability, dipole moment, rotational constant, principal moment of inertia, ground-state energy, and orbital energies, were investigated and compared to previously reported data. The elastic and inelastic channels showed the appearance of shape and Feshbach resonances for pyrrole and its isomers. The ultralow-energy region resonance was observed for Z-2 butenenitrile at 0.47 eV. With STO-3G and DZP basis sets, we estimated elastic, excitation, and momentum-transfer cross sections. The differential cross section for the present polar molecules was studied at 5 eV. The dissociative electron attachment channel for pyrrole and its isomers was studied for the pyrrolide anion. The data presented here will be helpful in astrophysical, astrochemical, atmospheric, and low-energy plasma modeling due to the presence of pyrrole and its isomers and the pyrrolide anion in the celestial bodies. The estimated data are also helpful in the biomedical field, radiation therapy, and pharmaceuticals.

Gas heating by inductively coupled low-pressure chlorine process plasmas

The mechanism of gas heating in low-pressure inductively coupled chlorine plasma is analyzed using a self-consistent two-dimensional axisymmetric fluid plasma model that is coupled with the compressible Navier–Stokes equations. For gas pressures of 10 and 20 mTorr and the discharge power in the range 0.1–1.3 kW, the main reactions contributing to gas heating were the ion–ion recombination reactions and the quenching of electronically excited chlorine atoms. At the same time, the energy released by the electron impact dissociation reaction of molecular chlorine is negligible due to its high degree of dissociation within the plasma bulk. The comparison between the results of our simulations and the fitting equation proposed in the literature show qualitative agreement, although there is significant quantitative discrepancy.

Analytic Solution of the System of Integro-Differential Equations for the Plasma Model in an External Field

Analytic Solution of the System of Integro-Differential Equations for the Plasma Model in an External Field

Martian global current systems and related solar wind energy transfer: hybrid simulation under nominal conditions

ABSTRACT The magnetized solar wind drives a current system around Mars that maintains its induced magnetosphere. The solar wind also transfers its energy to the atmospheric ions, causing continuous atmospheric erosion, which has a profound impact on the planet’s evolution history. Here, we use Amitis, a Graphics Processing Unit (GPU)-based hybrid plasma model to first reproduce the global pattern of the net electric current and ion currents under an interplanetary magnetic field perpendicular to the solar wind flow direction. The resultant current distribution matches the observations and reveals more details. Using the electric field distribution characterized earlier with the same model, we calculate for the first time the spatial distribution of energy transfer rate to the plasmas in general and to different ion species at Mars. We find out that (1) the solar wind kinetic energy is the dominant energy source that drives Martian induced magnetosphere, (2) the energy flux of the shocked solar wind flows from the magnetic equatorial plane towards the plasma sheet in the induced magnetotail, (3) both the bow shock and the induced magnetospheric boundary are dynamos where plasma energy is transferred to the electromagnetic field, and (4) the planetary ions act as loads and gain energy from the electromagnetic field. The most intense load region is the planetary ion plume. The general pattern of the energy transfer rate revealed in this study is common for induced magnetospheres. Its variabilities with the upstream conditions can provide physical insight into the observed ion escape variabilities.

Nonplanar ion-acoustic solitary and cnoidal waves in a non-Maxwellian plasma: Study on nonplanar (modified) Kawahara equation

This study aims to examine the properties of the nonplanar (cylindrical and spherical) ion-acoustic solitary waves (SWs) and cnoidal waves (CWs) in a collisionless, unmagnetized electron-ion (EI) plasma having a Cairns–Tsallis distribution for the electrons. This study is structured around two main lines. The first trend involves deriving the nonplanar Korteweg-de Vries (KdV) equation by utilizing the method of reductive perturbation (MRP). This equation describes small-amplitude (non)planar acoustic waves (AWs). Furthermore, the nonplanar Kawahara equation (KE) is formulated to examine the significant magnitude of planar and nonplanar SWs and CWs. The current plasma model supports compressive and rarefactive IA solitary and cnoidal structures, depending upon the associated physical factors such as the nonextensive parameter (nonextensivity) and nonthermal parameter (nonthermality). When the plasma compositions reach some critical values, such as the critical value of nonthermality, the coefficient of the quadratic nonlinear term vanishes. Hence, both nonplanar modified KdV (mKdV) equation and modified KE (mKE) with cubic nonlinearity are derived to accurately depict the dynamics of both small and large amplitudes of nonplanar SWs and CWs and any other structures related to this family of evolution equations. The influences of the nonextensivity and nonthermality on the profile of (non)planar KdV soliton and the (non)planar Kawahara SWs and CWs are numerically examined using some semi-analytical and numerical approximations. Also, the impact of the nonextensivity on the profile of (non)planar mKdV soliton and the (non)planar modified Kawahara SWs and CWs is reported. It is tracked down that the variety of different plasma parameters significantly alters the characteristic properties of the small and large amplitude ion-acoustic waves (IAWs) discussed by the nonplanar KdV-type equations.

Electrostatic solitary waves in a bi-ion plasma with two suprathermal electron populations – application to Saturn’s magnetosphere

ABSTRACT Non-thermal particle distributions characterized by a high-energy tail are ubiquitous in space plasmas. They are usually described by a kappa distribution function, that has been shown to be an excellent fit in most real circumstances. Among other space missions, Cassini and Voyager have both recorded evidence of a coexistence of non-thermal electron populations (with different characteristics) in Saturn’s magnetosphere, and subsequent studies showed that these are well-described by using different tailor-fit realizations of the (parametrized) kappa distribution. Motivated by these observations we have formulated a multifluid plasma model incorporating two types of (positive) ions and two distinct kappa-distributed electron populations, in order to study electrostatic solitary waves (ESWs) in Saturn’s magnetosphere from first principles. Our analysis reveals that the spectral index (in fact, the κ parameter value related to the cold electron population mainly) is vital in explaining the difference among different types of non-linear structures. A comparison with spacecraft observations suggests that our theoretical model provides an efficient framework for the interpretation of ESW observations in Saturn’s magnetosphere. Our qualitative predictions may also apply to other planetary magnetospheres, where a similar multispecies plasma composition may be present.

Constraining the equation of state with heavy quarks in the quasi-particle model of QCD matter

In a quasi-particle model of QCD matter at finite temperature with thermal masses for quarks and gluons from hard thermal loops, the equation of state (EOS) can be described by an effective temperature dependence of the strong coupling g(T). Assuming the same effective coupling between the exchanged gluon and thermal partons, the EOS can also be related to parton energy loss. Based on the quasi-particle linear Boltzmann transport (QLBT) model coupled to a (3+1)-dimensional viscous hydrodynamic model of the quark-gluon plasma (QGP) evolution and a hybrid fragmentation-coalescence model for heavy quark hadronization, we perform a Bayesian analysis of the experimental data on D meson suppression RAA and anisotropy v2 at RHIC and the LHC. We achieve a simultaneous constraint on the QGP EOS and the heavy quark transport coefficient, both consistent with the lattice QCD results.

N-dodecane partial oxidative reforming in gliding arc discharge plasma and kinetic model

A gliding arc discharge (GAD) plasma reactor was developed for partial oxidative reforming (POR) H2 production. Air was used as carrier gas and oxidant. The effects of the molar ratio of oxygen to carbon(O/C), input power and residence time on POR reaction were investigated. Under O/C ratio 0.75, input power 35 W and residence time 35 s, the energy yield of H2 was 68.7 L/kWh and the main products were H2 and CO. The GAD plasma was diagnosed with OES. A zero-dimensional(0-D) reaction kinetic model of was established. The simulation results were consistent with the experimental ones. The mechanism of C12H26 conversion, the generation and consumption of products were discussed in detail. The experiment results were in good agreement with the simulated ones. The primary path of n-dodecane conversion was the direct cracking reaction and H2 mainly derived from the recombination reaction between H atom and CH4, C3H6 and C2H6.