Plasma Formation Research Articles

Medium-induced radiation with vacuum propagation in the pre-hydrodynamics phase

The recent discovery of the potential of jet quenching observables to constrain the initial stages after a heavy-ion collision makes imperative to have a better understanding of the process of medium-induced radiation before the formation of the quark-gluon plasma (QGP) and its impact on observables at high-pT. In this work, we generalize the BDMPS-Z framework for medium-induced radiation to account for additional emissions occurring before the creation of the QGP. For simplicity, we assume that during the pre-hydrodynamics phase the hard parton propagates as in vacuum. This set-up, allows us to isolate the contribution from the additional initial radiation by comparing with the usual scenarios in which the emitter is created inside the medium but with different starting points. Using both a numerical implementation of the fully resummed emission spectrum and the usual analytical approximations, we find that replacing an initial slab of the medium by vacuum yields to a significant reduction of the emission spectrum for low radiated gluon energies, while the high-energy tails remain largely unmodified. Finally, we assess the effect of replacing the initial medium by vacuum propagation on the single-inclusive particle suppression RAA and high-pT azimuthal asymmetry v2. Our findings indicate that considering vacuum propagation prior to hydrodynamization leads to an increase in the v2, thus corroborating the importance of the treatment of jet quenching in the initial stages for the correct description of both observables.

Numerical investigation of hydrogen production from low-pressure microwave steam plasma

Hydrogen is recognized as a suitable energy carrier that can facilitate the storage and transport of renewable energy. In this context, hydrogen production from microwave-excited steam plasma is one of the least researched techniques and lacks numerical study due to the complex plasma kinetics and difficullty of the simulation process. Therefore, in this study, a kinetic model is developed for steam plasma, considering forty-one reactions and fourteen species. Two-dimensional microwave steam plasma is modeled using COMSOL Multiphysics software for the first time. At a microwave power of 800 W, plasma formation and hydrogen production from low pressure (1 Torr) and high temperature (150 °C) steam plasma are numerically studied within the time domain of 10−10 to 10−4 s. The presented results demonstrate that the maximum electron density reaches 5 1017m−3 at 10−4s, and 16.8% of the water molecules dissociate to form various species. The conversion rate of water molecules to hydrogen is calculated as 24%. According to the thermodynamic evaluations, the proposed system's energy and exergy efficiencies are 10.31% and 10.14%, respectively, with a hydrogen production rate of 0.68 μg/s. Furthermore, the effect of the applied microwave power on plasma properties and hydrogen production is parametrically studied. Despite the proportional relationship between the input power and hydrogen production, no correlation is found between microwave power and system efficiency.

NON-RESONANT MICROWAVE DISCHARGE START-UP IN HELIOTRON J

The non-resonant microwave discharge in strong magnetic fields was investigated in Heliotron J under the condition, ωce/ωMW > 1 (ωce and ωMW are the angular electron cyclotron frequency and the angular microwave frequency, respectively). Following the production of a non-resonant microwave discharge plasma, it undergoes several phases in sequence: breakdown and formation of pre-ionized plasma, increase in linear and nonlinear phases of plasma density, and quasi-stationary stage. Several modes of non-resonant microwave discharge were investigated. In the power-scanning mode in non-resonant microwave discharge, a higher plasma density than that in the constant-power mode is achieved. The maximum average density achieved in the experiments is substantially greater than the critical density for O-wave (ordinary waves) 7.45 ⸱1016 m -3 and can reach the value of 2.5⸱10 18 m -3. .

Semianalytical calculation of the trajectory of relativistic nuclear collisions in the QCD phase diagram

We extend a semianalytical model that includes the finite nuclear thickness to calculate the energy density $\ensuremath{\epsilon}(t)$ and conserved-charge densities including the net-baryon density ${n}_{\mathrm{B}}(t)$ produced at mid-spacetime-rapidity in central Au + Au collisions. Assuming the formation of a quark-gluon plasma with an ideal gas equation of state of either quantum or Boltzmann statistics or with a lattice QCD-based equation of state, we extract the temperature $T$ and chemical potentials ${\ensuremath{\mu}}_{\mathrm{B}}, {\ensuremath{\mu}}_{\mathrm{Q}}$, and ${\ensuremath{\mu}}_{\mathrm{S}}$ as functions of time. This then allows us to semianalytically calculate the $T\text{\ensuremath{-}}{\ensuremath{\mu}}_{\mathrm{B}}$ trajectory of relativistic nuclear collisions in the QCD phase diagram, which should benefit the studies of high density physics including the search for the critical endpoint. This model is also useful for exploring the trajectories in the more general $T\text{\ensuremath{-}}{\ensuremath{\mu}}_{\mathrm{B}}\text{\ensuremath{-}}{\ensuremath{\mu}}_{\mathrm{Q}}\text{\ensuremath{-}}{\ensuremath{\mu}}_{\mathrm{S}}$ QCD phase space.

Design of an optimised movable electrostatic diagnostic for the investigation of plasma properties in a large negative ion source

This contribution describes the design of a movable Langmuir probe system to be permanently installed in the SPIDER negative ion source. This diagnostic aims at measuring the axial profiles of plasma density, electron temperature and floating potential in both the driver and the expansion region, with a view to further investigate the positive ion dynamics. Furthermore, a deeper understanding of the plasma formation mechanism and of the RF coupling can be provided, e,g. via the estimation of the Electron Energy Distribution Function (EEDF) inside the driver. Thermal analyses were performed to define both the allowable duration of the probe exposure to the plasma and the extent of the voltage sweep. The maximum exposure time for the probe shaft is 10 s, thus a fast manipulation system is included in the design. The integration in the SPIDER source is described, considering all the limitations due to the space availability, the presence of the RF generators and the vacuum-compatibility requirements. To comply with all the constraints, several solutions are proposed for the probe head design.

A retrospective cohort study of the effect of intravenous tranexamic acid infusion on geriatric hip fractures patients undergoing proximal femoral nail antirotation

Background: Tranexamic acid (TXA) has been used in the management of bleeding. We are conducting a retrospective cohort study to analyse the effect of intravenous TXA infusion on the surgical outcomes of geriatric hip fracture cases which undergoes proximal femoral nail antirotation. Methods: In this study, 364 patients who had undergone proximal femoral nail antirotation between January 2018 and December 2019 in United Christian Hospital have been recruited. Two-hundred thirteen patients were recruited in controlled group and 151 patients were recruited in TXA group. One gram of TXA acid was injected intravenously on induction of anaesthesia and before surgical incision. Outcomes including length of stay, operation time, intraoperative blood loss, haemoglobin and haematocrit drop and post-operative blood transfusion have been measured. Results: There was a reduction in operative time, intraoperative blood loss, post-operative haemoglobin and haematocrit drop and post-operative blood transfusion in TXA group, with a reduction in the intraoperative blood loss (Controlled group: 97.8 ± 67.7 ml, TXA group: 76.0 ± 71.4, Difference −22.3%, p-value: 0.0036) and post-operative haematocrit drop (Controlled group: 0.04 ± 0.03, TXA group: 0.03 ± 0.03, Difference −25%, p-value: 0.05) being statistically significant. The length of stay is not statistically significant between the two groups. TXA is an antifibrinolytic agent which acts by binding to plasminogen which inhibits plasma formation. It has a potential reduction in blood loss in major operations. Conclusion: Intravenous TXA infusion helps to reduce blood loss in a patient undergoing proximal femoral nail antirotation. It is safe to use in the geriatric group of patients. We would recommend the usage of TXA infusion to improve the surgical outcome.

Effects of ion temperature on detached plasma formation using a linear divertor simulator TPDsheet-U

The effect of ion cyclotron resonance heating (ICRH) on the detached plasma formation process was investigated using a linear divertor simulator, TPDsheet-U. We measured the stored energy (ion temperature), electron temperature, electron density, and Balmer series emission intensity ratio of the plasma while increasing the ICRH RF power from 0 to 400 W. It was observed for the first time that the electron temperature of detached plasma increased and the Balmer series emission intensity ratio became smaller when the ion temperature was increased by applying a resonance frequency ωRF, which is about 1.2 times the ion cyclotron frequency ωci of hydrogen ions. This suggests that increasing the ion temperature causes a transition from a detached plasma to an attached plasma.

Recrystallization in string-fluid complex plasmas

The process of string-like cluster formation in complex plasmas is investigated. Excellent qualitative agreement between experiment and simulation showed that the reduced repulsion in the interparticle potential was enough to induce the formation of this structure

Electromagnetic enhanced ignition of octogen explosive at subnormal temperatures: A numerical study

The thermal decomposition and ignition of high-performance high explosives occur via a mechanism where the solid phase sublimes and the parent molecules decompose rapidly in the gas phase to form unstable and charged intermediates. These intermediates continue to react and form the final products to release energy and do work. We have observed that the presence of electromagnetic energy significantly reduces the ignition temperature of a common high explosive, and data suggest that this occurs via electromagnetic interactions with the charged gas-phase intermediates. Here, we modified the thermal decomposition kinetic expressions for octogen (High Melt eXplosive, HMX) to couple the effects of an incident microwave (MW) field. This modified kinetic model is used to investigate our previous experimental work which showed that the surface temperature at ignition of HMX powder is reduced by the MW field. The Fridman–Macheret α-model is a common approach in plasma chemistry and was incorporated into the Henson/Smilowitz HMX kinetics; this effectively reduces the activation energy (Ea) by vibronically excited charged reactive intermediates. A modified kinetic model was implemented into the COMSOL Multiphysics Software. The thermal time to ignition was validated; as a result, plasma formation reduced the surface temperature by ∼23 °C compared to thermal ignition. With a validated kinetic model that can simulate both pure thermal ignition and mixed thermal/plasma ignition, we are able to simulate our previous experimental work showing that plasma ignition reduces the surface temperature at ignition compared to thermal initiation.

The Relationship between Coagulation and Infertility: A Mini-Review

Infertility is a common problem that affects many couples worldwide, with an estimated 48.5 million couples experiencing infertility. The causes of infertility are diverse and complex, with a combination of genetic, environmental, and lifestyle factors contributing to the problem. While reproductive medicine has advanced significantly in recent years, the diagnosis and treatment of infertility remains a challenge, particularly in cases where the cause is not clear. One factor that has been found to contribute to infertility is abnormalities in coagulation. Coagulation is an essential process that helps to prevent bleeding and promote healing after injury. However, when coagulation is abnormal, it can lead to various health problems including infertility. Studies have shown that coagulation disorders may affect reproductive function by interfering with blood flow, ovulation and implantation may lead to inflammation and oxidative stress. Moreover, the balance between coagulation and fibrinolysis is crucial in coagulum formation and liquefaction of seminal plasma in males. Despite the growing body of research on the relationship between coagulation and infertility, there is still much to be learned. In this review, we will examine the current understanding of the relationship between coagulation abnormalities and infertility. We will discuss the potential mechanisms by which coagulation disorders may affect reproductive function and explore the evidence linking coagulation disorders to infertility, recurrent pregnancy loss, and implantation failure. Finally, we will consider the implications of these findings for clinical practice and future research.

Analysis of the efficiency of MHD cycle supported by nanosecond pulsed discharge pre-ionization

A numerical analysis of plasma generation by a nanosecond pulsed discharge in a strong magnetic field was performed. A 2D model of the plasma formation and decay in magnetohydrodynamic (MHD) channel has been elaborated. A comparison with experimental results demonstrates good agreement between calculated and measured plasma distribution in the channel. Preliminary analysis of the efficiency of the MHD-generator based on the nanosecond dielectric barrier discharge flow pre-ionization shows that the ratio of the power required to maintain ionization in the flow to the power extracted from the flow in MHD process is ∼3% for an ideal Faraday MHD generator with segmented electrodes with BY ∼ 5 T and supersonic flow speed uZ ∼ 1600 m s−1. Such a high energy efficiency of the generator allows us to consider this concept of the generator as promising for energy generation and flow control.

Effect of the thermalization of secondary electron energies on plasma formation during the irradiation of heavy ions

This study aims at understanding the effect of the thermalization of secondary electrons produced by incident heavy-ion impact ionization on plasma formation. The motions of the secondary electrons were simulated using pseudo-initial secondary electron energy distribution functions. These simulations allowed us to estimate the times when thermalization occurred and the probabilities of secondary electrons escaping the electric field created near the incident ion path according to the initial secondary electron energy distribution functions. The probabilities and thermalization processes were found to be almost independent of these functions which indicated that the secondary electrons were thermalized before the plasma was formed.

Jet fragmentation via azimuthal angular correlations of electrons from heavy flavor decay in pp, p -Pb, and Pb-Pb collisions using PYTHIA8+Angantyr calculations

Measurements in heavy flavor azimuthal angular correlation provide insight into the production, propagation, and hadronization of heavy flavor jets in ultrarelativistic hadronic and heavy-ion collisions. These measurements across different colliding systems, such as $p\text{\ensuremath{-}}A$ and $A\text{\ensuremath{-}}A$, help us isolate the possible modification in particle production due to cold nuclear matter (CNM) effects and the formation of quark-gluon plasma (QGP), respectively. Jet correlation studies give direct access to the initial parton dynamics produced in these collisions. This article studies the azimuthal angular correlations of electrons from heavy flavor hadron decays in $pp, p$-Pb, and Pb-Pb collisions at $\sqrt{{s}_{NN}}=5.02$ TeV using $\text{PYTHIA8}+\text{Angantyr}$. We study the production of heavy flavor jets with different parton level processes, including multiparton interactions, different color reconnection prescriptions, and initial and final state radiation processes. In addition, we add the hadron-level processes, i.e., Bose-Einstein and rescattering effects, to quantify the effect due to these processes. The heavy flavor electron correlations are calculated in the different trigger and associated ${p}_{\mathrm{T}}$ intervals to characterize the impact of hard and soft scattering in the various colliding systems. The yields and the sigmas associated with the near-side (NS) and away-side (AS) correlation peaks are calculated and studied as a function of associated ${p}_{\mathrm{T}}$ for different trigger ${p}_{\mathrm{T}}$ ranges.

On the Role of Runaway Electrons in Stimulating the RF Breakdown and Plasma Formation in Torsatrons Uragan-3M, Uragan-2M

We consider a scenario of the initial stage of the RF breakdown of a working gas in torsatrons Uragan-3M and Uragan-2M and the roles of runaway electrons in this process. In our previous works, we studied only the acceleration factor of the breakdown process which occurs, when the intensity of the flow of runaway electrons increases due to the stimulation by an additional ultrahigh-frequency discharge at the front edge of a magnetic field pulse. This work attempts to describe the individual phenomena that accompany the initial stage of plasma formation in the confinement areas of torsatrons Uragan-3M and Uragan-2M in the presence of the flow of runaway electrons.

Simultaneous measurement of carbon emission and gas temperature via laser-induced breakdown spectroscopy coupled with machine learning.

A method, which can accurately measure carbon emission and gas temperature simultaneously in real-time from a laser-induced breakdown spectrum (LIBS) via machine learning, is proposed in this study. In typical, peak intensity ratios had been used to map species concentrations prior to plasma formation, after removing the broadband continuum of the spectrum; however, the dependence of these peak intensity ratios on the concentration changes with the change in gas density. Therefore, considering the fact that the strength and shape of this broadband continuum is a function of the gas density for a given optical setup, we attempted to collect a spectrum by shortening the time delay after the laser fire, such that the spectrum can contain some of the broadband continuum. Since the analytical quantification of this broadband continuum is not trivial, we employed a machine learning approach to acquire a model that simultaneously predicts the gas temperature and CO2 concentration. The predictive performance of the model trained with spectra that contain the broadband continuum was much better than that without it; the gradient-weighted regression activation mapping (Grad-RAM) analysis revealed that the model utilizes the broadband spectrum for temperature prediction and correction of changes in peak intensity due to temperature changes in the concentration prediction process.

Laser-Induced Ion Formation and Electron Emission from a Nanostructured Gold Surface at Laser Fluence below the Threshold for Plasma Formation.

The laser formation of positive and negative ions on a nanostructured metal surface is observed at laser fluence below the plasma formation threshold. The laser radiation energy dependences of the yield of positive and negative Au ions and charged clusters as well as electrons from the laser-induced nanostructures on the surface of gold are obtained at laser fluence below the plasma formation threshold using a pulsed laser with a wavelength of 355 nm and a pulse duration of 0.37 ns. It is shown that the ratio of the signals of positive and negative ions is constant over the entire range of the laser radiation energies, while the ion signal dependence on the laser radiation energy is described by a power function with an exponent of 9. The role of gold nanoparticles with a size of less than 5 nm in the formation of Au ions and charged Au clusters is discussed.

Data transfer for STAR grid jobs

The Solenoidal Tracker at RHIC (STAR) is a multipurpose experiment at the Relativistic Heavy Ion Collider (RHIC) with the primary goal to study the formation and properties of the quark-gluon plasma. STAR is an international collaboration of member institutions and laboratories from around the world. Yearly data-taking period produces PBytes of raw data collected by the experiment. STAR primarily uses its dedicated facility at BNL to process this data, but has routinely leveraged distributed systems, both high throughput (HTC) and high performance (HPC) computing clusters, to significantly augment the processing capacity available to the experiment.The ability to automate the efficient transfer of large data sets on reliable, scalable, and secure infrastructure is critical for any large-scale distributed processing campaign. For more than a decade, STAR computing has relied upon GridFTP with its x509-based authentication to build such data transfer systems and integrate them into its larger production workflow. The end of support by the community for both GridFTP and the x509 standard requires STAR to investigate other approaches to meet its distributed processing needs.In this study we investigate two multi-purpose data distribution systems, Globus.org and XRootD, as alternatives to GridFTP. We compare both their performance and the ease by which each service is integrated into the type of secure and automated data transfer systems STAR has previously built using GridFTP. The presented approach and study may be applicable to other distributed data processing use cases beyond STAR.

Full-wave and plasma simulations of microstrip excited, high-frequency, atmospheric pressure argon microdischarges

Two-dimensional fully coupled electromagnetic (EM) wave-plasma simulations are used to study the formation, early transient and quasi-steady state of the argon plasma excited by a two-dimensional discontinuous microstrip line. The EM waves that normally propagate in the microstrip transmission line, radiate and scatter at the position of the gap and the electric field is enhanced primarily at the corner of the gap. The microdischarge is preferentially formed at this position of the EM field hotspot and in low frequencies propagates on the dielectric surface, much like a microwave surface streamer. In longer times, diffusion dominates and the whole gap is filled with plasma of maximum density in the order of 1020 while it occupies a volume larger than the gap. Cycle-averaged mean electron temperatures range from 2.8 to 3.9 eV, while the plasma reaches a quasi-static regime in approximately 2 µs having reconfigured the transmission and radiation patterns of the slitted microstrip line. The tunability of the microstrip due to plasma formation provides means for sustaining the discharge in a stable regime. For the same input EM power, the electron temperature increases with increasing excitation frequency while electron densities found to decrease. For the same wave frequency, a decrease of the electron densities with increasing gap is also found in addition to a restriction of the discharge expansion. Finally, thicker dielectrics result to higher electron densities and electron temperatures as well as absorbed power from the plasma. These findings are attributed to the dependence of absorbed EM power and skin depth on the EM wave angular frequency, the critical for shielding electron density as well as the restructuring of the S-parameters due to the changes in operational parameters.

Non-thermal plasma dielectric barrier discharge reactor stability analysis using fiber bragg grating sensor

The main focus in this study is to determine the stability of the plasma generated by a Dielectric Barrier Discharge (DBD) reactor in the presence and without glass beads as dielectric enhancement. The stability of plasma was determined based on plasma temperature which measured within plasma stream. The DBD plasma reactor was designed, fabricated and being operated in an open air system. Fiber Bragg grating (FBG) was used to measure the plasma temperature. The applied voltage was increased up to 8 kV to determine breakdown voltage and evaluate plasma stability with and without the presence of glass beads as dielectric enhancement. Experimental results revealed that plasma started to generate at applied voltage about 3.0 kV. Plasma formation found generated with stable at applied voltage 8 kV for both with and without the presence of glass beads. With the presence of glass beads, the plasma temperature found much higher about 180 °C compare with without glass beads which is about 90 °C, and yet the plasma generation is still stable.

Supersonic water jets as point-like sources of extremely high pressure

Two interacting supersonic water jets and collisions of a water jet with an aluminum target are studied experimentally and by hydrodynamic simulations. Supersonic water jets form, when shocks generated by underwater electrical explosions of conical wire arrays converge. The arrays are supplied by a ∼250 kA, ∼1 μs rise time current pulse. Underwater explosion of two conical arrays placed face to face produces jets propagating in air with velocities of ∼2.5×103 m/s leading to hot plasma formation at a temperature of ∼2200–3000 K, pressure ∼1.7×1010 Pa, and density >1029 m−3. When a single array explodes underwater in front of an aluminum target, the collision of the jet with the target produces a local pressure of ∼3×1010 Pa on the surface of the target.