Neutral Jet Research Articles

Techno-economic assessment of modified Fischer-Tropsch synthesis process for direct CO2 conversion into jet fuel

Direct use of CO2 through modified Fischer-Tropsch synthesis (FTS) process presents a viable approach for the production of carbon–neutral jet fuel. However, achieving high performance for the CO2-FTS process remains a significant challenge. Current technology can only achieve low CO2 conversion and low jet fuel yield using tailored catalysts, which hinders the commercial deployment of direct CO2-FTS process. This paper presents a techno-economic assessment (TEA) of jet fuel production via CO2-FTS process at commercial-scale. Two ex-situ water removal configurations: (a) multi-stage CO2-FTS process and (b) CO2-FTS with tail gas recycle process were conducted to assess their potential for performance improvement. Process performance was evaluated using a model developed in Aspen Plus® linking with Aspen Custom Modeller® (ACM), while economic evaluation was carried out in Aspen Process Economic Analyzer®. The CO2-FTS model was based on first principles and modified Anderson-Schulz-Flory (ASF) distribution. Results indicated that both ex-situ water removal configurations can significantly improve the process performance. CO2-FTS process with 90% tail gas recycle has the best performance for both technical and economic analysis. The process achieved 85.8% CO2 conversion and 35.6% jet fuel yield with the lowest energy demand of 4.57 MWh per tonne of produced jet fuel. Moreover, it boasts the lowest minimum selling price (MSP) of jet fuel at US$2.6/kg despite incurring the second-highest capital expenditure cost of M$ 451.3. A comparison of the two ex-situ water removal configurations at 61.9% and 76.5% CO2 conversion, suggests that both processes exhibit comparable technical performances, yet the recycling of tail gas holds the potential to reduce economic costs. Consequently, this study will inspire researchers on process improvement and cost reduction of the commercial-scale CO2-FTS jet fuel production.

Mechanisms and characterization of a novel hybrid laser-enhanced particle laden electrochemical fabrication process for high quality micro-dimples on germanium wafers

The first-generation semiconductor materials represented by silicon (Si) and germanium (Ge) still hold a dominant position in many fields, including micro-electromechanical systems (MEMS) and integrated circuits (ICs). The processing of these materials continues to attract significant research attention for improvements in quality and efficiency. This study proposes a novel hybrid laser-enhanced particle-laden electrochemical machining (LEPL-ECM) process, whereby pulsed laser irradiation is utilized to selectively and locally enhance the electrical conductivity of Ge at specific locations. A neutral electrolyte jet, containing abrasive diamond particles, is applied to the location on the wafer surface opposite the laser irradiation, facilitating a localized and enhanced electrochemical dissolution. The effect of micro-particle erosion effectively removes the generated oxides and potential passivation layers, ensuring continuous and efficient electrochemical reactions. Consequently, high-quality micro-dimples with an entrance diameter of about 380–800 μm, a depth of around 138–300 μm, and a quasi-mirror surface with the roughness (Sa) of as low as 59.8 nm can be achieved within 90 s. Furthermore, the effects of the applied voltage, laser power and processing time on the resulting dimple characteristics and surface quality are discussed, along with a detailed morphology characterization. Dense micro-pits, radial streamlined micro-grooves and a special transitional region have been observed on dimple center, sidewall and near the edge, respectively, and the formation mechanism have been analyzed. Finally, a simulation of the electrolyte jet induced fluid pressure and velocity as well as the particle trajectory and distributions within and surrounding the dimple structure was conducted, which reveals that the synergistic mechanism associated with the hybrid material removal process involves both electrochemical corrosion and abrasive erosion.

Semi-inclusive deeply inelastic electron nucleus scattering in the eN collinear frame

Our understanding of the parton-level structure in the nucleon comes predominantly from the electron deeply inelastic scattering measurements with very high precision. It deserves further study. We therefore calculate the neutral current jet production semi-inclusive deeply inelastic scattering process in this paper. Neutral current implies that interactions can be mediated by the photon, Z0 boson and their interference. The initial electron is assumed to be polarized and then scattered off by a target particle with spin 1. After obtaining the differential cross section, we calculate sets of quantities, including structure functions, azimuthal asymmetries, parity-violating asymmetries and charge asymmetries. They can be measured in the experiments. We find that these quantities are expressed in terms of the parton distribution functions and the electroweak coefficients. These coefficients are different from that in the γ⁎N collinear frame. As a result, our calculation provides a set of new quantities for determining the electroweak couplings as well as the parton distribution functions in the deeply inelastic scattering. It is helpful to test the universality of the parton distribution functions or to understand the hadronic weak interactions and strong interactions simultaneously.

Intrinsic asymmetries in semi-inclusive deeply inelastic scattering at the Electron-Ion Collider

We calculate the neutral current jet production semi-inclusive deeply inelastic scattering process in this paper. Neutral current implies that interactions can be mediated by the photon, $Z^0$-boson and their interference. The initial electron is assumed to be polarized and then scattered off by a target particle with spin-1/2. Calculations are carried out up to twist-3 level in the quantum chromodynamics parton model by applying the collinear expansion formalism where multiple gluon scattering is taken into account and gauge links are obtained automatically. After obtaining the differential cross section, we introduce the definition of the intrinsic asymmetry. This quantity reveals the asymmetry in the distribution of the quark intrinsic transverse momentum. We find that these asymmetries can be expressed in terms of the transverse momentum dependent parton distribution functions and the electroweak couplings. As a result, our calculations provide a set of new quantities for analyzing the parton distribution functions and the electroweak couplings. It is helpful to understand the hadronic weak interactions and strong interactions in the deeply inelastic scattering process simultaneously.

Carbon Neutral Jet Fuel From The Sun

Aldo Steinfeld from ETH Zurich discusses an industrial plant capable of producing carbon neutral jet fuel from sunlight

Turbulence structure of neutral and negatively buoyant jets

Abstract

Experimental investigation into turbulent negatively buoyant jets using combined PIV and PLIF measurements

Turbulent negatively buoyant jets occur when the buoyancy of a jet opposes its source momentum. In these flows, the fluid will rise until it reaches a stagnation point and a return flow is established, forming a fountain (Hunt and Burridge, 2015). This study looks at both the initial negatively buoyant jet stage of this flow, before the return flow has established, and the fully developed fountain stage. Two-dimensional particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) are used to simultaneously measure the velocity and scalar concentration fields. An experimental and image processing procedure for the PLIF is introduced that accounts for pulse-to-pulse variations in laser power and beam profile for an Nd:YAG laser, which has been demonstrated to reduce the error in scalar concentration measurements. The flow is investigated experimentally using a 1m3 tank of salt-water ambient with freshwater + ethanol negatively buoyant jets, allowing for measurements to be taken at Fro=30 and Reo=5900. The entrainment coefficient for a negatively buoyant jet has been estimated as α ≅ 0.054, lower than a neutral jet at α ≅ 0.058. A finding consistent with existing literature (Bloomfield and Kerr, 2000; McDougall, 1981).

Jet-hadron correlations relative to the event plane at the LHC with ALICE

In ultra relativistic heavy-ion collisions at the Large Hadron Collider (LHC), conditions are met to produce a hot, dense and strongly interacting medium known as the Quark Gluon Plasma (QGP). Quarks and gluons from incoming nuclei collide to produce partons at high momenta early in the collisions. By fragmenting into collimated sprays of hadrons, these partons form 'jets'. The outgoing partons scatter and interact with the medium, leading to a manifestation of medium modifications of jets in the final state, known as jet quenching. Within the framework of perturbative QCD, jet production is well understood in pp collisions. We use jets measured in pp interactions as a baseline reference for comparing to heavy-ion collision systems to detect and study jet quenching. The jet quenching mechanism can be studied through the angular correlations of jets with charged hadrons and is examined in transverse momentum (pT) bins of the jets, pT bins of the associated hadrons, and as a function of collision centrality. A robust and precise background subtraction method is used in this analysis to remove the complex, flow dominated, heavy-ion background. The analysis of angular correlations for different orientations of the jet relative to the event plane allows for the study of the path-length dependence of medium modifications to jets. The event plane dependence of azimuthal angular correlations of charged hadrons with respect to the axis of an R=0.2 reconstructed full (charged + neutral) jet in Pb–Pb collisions at sNN=2.76 TeV in ALICE is presented. Results are compared for three angular bins of the jet relative to the event plane in mid-peripheral events. The yields relative to the event plane are presented and then quantified through yield ratio calculations. The results show no significant path-length dependence on the medium modifications.

A numerical study of ponderomotive ion acceleration in a dense plasma driven by a circularly polarized high-intensity laser beam normally incident on thin foils

AbstractWe use an Eulerian Vlasov code to study the efficient ion acceleration in dense targets by the ponderomotive force of a high-intensity circularly polarized laser beam, normally incident on a dense plasma. The code solves the one-dimensional relativistic Vlasov–Maxwell equations for both electrons and ions. We follow in details the mechanism of formation and evolution of a double-layer structure, where electrons are pushed steadily in the forward direction by the ponderomotive force of the laser beam, trapping an ion population, while an induced space charge electric field pulls ions behind them, forming a double-layer structure supported by the strong ponderomotive pressure of the intense laser beam. We consider the case of a high-density deuterium plasma with n/ncr = 100, where ncr is the critical density. Three cases are studied, by varying the width of the dense target and the intensity of the laser beam (with the normalized vector potential or quiver momentum a0 = 50 and a0 = 100), to follow the physical processes involved in the ion acceleration and the final formation of a neutral plasma jet ejected from the back of the target. We follow the transition from a situation where the laser pulse radiation pressure is acting on the double layer in the target, to a situation where below a given thickness a fraction of the laser energy is transmitted through the target. The absence of noise in the Eulerian Vlasov code allows us to follow accurately the evolution of the phase-space structures of the distribution functions.

A Lagrangian Particle Transport and Diffusion Model for Non-passive Scalars

We present a model of the transport and diffusion of materials whose density differs from the ambient air density or where there is excess momentum above the ambient flow. The model describes the evolution of the material concentration and can be applied to both positively and negatively buoyant pollutants. In order to calculate the transport and diffusion, we use a Monte-Carlo technique to follow the Lagrangian trajectories of many particles. This makes the model suitable for the calculation of transport and diffusion in non-homogeneous areas such as complex terrain or within an urban canopy. Results are compared with wind-tunnel observations of neutral jet releases under different conditions. Comparisons with wind-tunnel observations are made also for releases of negatively and positively buoyant materials. The agreement with observations is good.

High-Velocity Neutral Plasma Jet Formed by Dense Plasma Deflagration

High-velocity high-energy-density plasma jets are an invaluable tool for studying plasma-material interactions under extreme thermal, physical, chemical, and electrostatic stresses. Such a jet has been generated in an experimental facility utilizing a pulsed plasma deflagration accelerator. Time-averaged and fast-frame-rate intensified charge-coupled device images of the plasma jet are presented, showing a concentrated high-density plasma near the exit that is characterized with laser interferometry.

Vlasov simulation of ion acceleration by an intense laser beam normally incident on a thin target

We use an Eulerian Vlasov code to study the radiation pressure acceleration of ions and the formation of plasma jets when a high-intensity circularly polarized laser beam is normally incident on a thin target. The code solves the one-dimensional (1D) relativistic Vlasov-Maxwell equations for both electrons and ions. We consider a deuterium plasma with a density n = 25ncr (ncr is the critical density, i.e. the cutoff density for the laser beam propagation). In the case we present, the target is sufficiently thin that a fraction of the incident laser beam is transmitted through it. Along with this, we observe first a leak or ejection of electrons in the forward direction from the back of the target, which is followed by the formation and ejection of a neutral plasma jet (a regime called “leaky light sail radiation pressure acceleration”). The Vlasov code allows to follow the evolution of the system, with an accurate representation of the phase-space structures of the distribution functions.

Neutral atomic jet generation by laser ablation of copper targets.

This work aimed the obtainment of a neutral atomic jet departing from a plume generated by laser ablation of copper targets. A pair of electrodes together with a transducer pressure sensor was used to study the ablated plume charge composition and also to measure the ion extraction from the plasma plume. The neutral beam was produced with this setup and the relative abundance of neutrals in the plasma was measured, it decreases from 30% to 8% when the laser fluence is varied from 20 J/cm(2) to 32 J/cm(2). The necessary voltage to completely remove the ions from the plume varied from 10 V to 230 V in the same fluence range. TOF analysis resulted in center of mass velocities between 3.4 and 4.6 km/s, longitudinal temperature in the range from 1 × 10(4) K to 2.4 × 10(4) K and a Mach number of M = 2.36, calculated using purely hydrodynamic expansion approximation.

Modelling penetration and plasma response of a dense neutral gas jet in a post-thermal quenched plasma

This paper is about the dynamics of gas jet injection and propagation into the cold, current quench (CQ) discharge following the thermal quench (TQ) phase of a disruption event. Understanding the processes involved in the interpenetration between a dense, fast-moving supersonic gas jet and a magnetized plasma is fundamental to the solution of the disruption mitigation problem using massive gas injection. An analytical model was developed that provides the penetration depth of the jet in the CQ discharge. The model developed incorporates the injector, the vacuum space between injector and plasma, and the low beta CQ plasma through which the jet penetrates. The radially moving gas stagnates at some point inside the plasma by formation of a ‘bottle shock’, resulting in a certain penetration depth. Consistent with experimental findings, it is shown that high fuelling efficiency >70% and good penetration beyond the q = 2 surface is possible in such plasma discharges, but in normal (unquenched) plasma discharges penetration of dense gas jets will be quite poor. The paper also sheds light on how the external plasma responds to allow interpenetration of perfectly insulating gas jet through a strong magnetic field B2/2μ0 ≫ ρu2. The paper also develops semi-analytical models for the response of the cold, high-current, collision-dominated plasma to the insertion of a dense neutral jet: the propagation of cooling waves out along the magnetic field lines, the heated and ionized surface layer which also expands outwards along the magnetic field lines, and the electrical breakdown of the neutral gas within the jet volume. Although good penetration in the ITER post-TQ discharge can be achieved, the plasma resistivity is only marginally enhanced. This may render repetitive gas inject ineffective, as the concept requires a sizable resistivity enhancement to initiate a current profile contraction, and resulting kink-tearing activity to suppress runaway avalanching.

Two-dimensional visualization of cluster beams by microchannel plates

An advanced technique for a two-dimensional real time visualization of cluster beams in a vacuum as well as of the overlap volume of cluster beams with particle accelerator beams is presented. The detection system consists of an array of microchannel plates (MCPs) in combination with a phosphor screen which is read out by a CCD camera. This setup together with the ionization of a cluster beam by an electron or ion beam allows for spatial resolved investigations of the cluster beam position, size, and intensity. Moreover, since electrically uncharged clusters remain undetected, the operation in an internal beam experiment opens the way to monitor the overlap region and thus the position and size of an accelerator beam crossing an originally electrically neutral cluster jet. The observed intensity distribution of the recorded image is directly proportional to the convolution of the spatial ion beam and cluster beam intensities and is by this a direct measure of the two-dimensional luminosity distribution. This information can directly be used for the reconstruction of vertex positions as well as for an input for numerical simulations of the reaction zone. The spatial resolution of the images is dominated by the granularity of the complete MCP device and was found to be in the order of σ≈100μm.

Ion acceleration and plasma jets driven by a high intensity laser beam normally incident on thin foils

AbstractWe study the problem of the radiation pressure acceleration of ions and the formation of plasma jets, driven by a high-intensity circularly polarized laser beam normally incident on thin plasma targets. We use an Eulerian Vlasov code to solve the one-dimensional relativistic Vlasov-Maxwell equations for both electrons and ions. We consider the case of a high density plasma with n/ncr = 100, where ncr is the critical density. Three cases are studied with different target thicknesses, to investigate the physical processes involved when decreasing the target thickness from several electron skin depths down to the order of one skin depth. The results show a more important acceleration of the ions when the thickness is decreased. Although we observe in all cases a neutral plasma jet ejected from the back of the target, the evolution of the system which leads to the formation of this neutral plasma jet is different in the three cases considered. In each case, this evolution will be studied in details. Also, a leak or ejection of electrons from the back of the target is observed in the thinnest case treated (thickness of the order of the skin depth), before the formation of the neutral plasma jet, a regime called leaky light sail radiation pressure acceleration. The absence of noise in the Eulerian Vlasov code allows an accurate representation of the phase-space structures of the distribution functions.

THE SPINDLE: AN IRRADIATED DISK AND BENT PROTOSTELLAR JET IN ORION

We present Hubble Space Telescope observations of a bent, pulsed Herbig–Haro jet, HH 1064, emerging from the young star Parenago 2042 embedded in the H ii region NGC 1977 located about 30' north of the Orion Nebula. This outflow contains eight bow shocks in the redshifted western lobe and five bow shocks in the blueshifted eastern lobe. Shocks within a few thousand AU of the source star exhibit proper motions of ∼160 km s−1 but motions decrease with increasing distance. Parenago 2042 is embedded in a proplyd—a photoevaporating protoplanetary disk. A remarkable set of Hα arcs resembling a spindle surround the redshifted (western) jet. The largest arc with a radius of 500 AU may trace the ionized edge of a circumstellar disk inclined by ∼30°. The spindle may be the photoionized edge of either a ∼3 km s−1 FUV-driven wind from the outer disk or a faster MHD-powered flow from an inner disk. The HH 1064 jet appears to be deflected north by photoablation of the south-facing side of a mostly neutral jet beam. V2412 Ori, located 1' west of Parenago 2042 drives a second bent flow, HH 1065. Both HH 1064 and 1065 are surrounded by LL Ori-type bows marking the boundary between the outflow cavity and the surrounding nebula.

Ion acceleration and plasma jet formation in the interaction of an intense laser beam normally incident on an overdense plasma: a Vlasov code simulation

We use an Eulerian Vlasov code for the numerical solution of the one-dimensional relativistic Vlasov?Maxwell set of equations to study the acceleration of ions during the interaction of a high-intensity circularly polarized laser beam normally incident on an overdense plasma target. Both electrons and ions are treated with a kinetic equation. We consider the case when the laser free space wavelength ? 0 is greater than the scale length of the jump in the plasma density at the target plasma edge Ledge (? 0 Ledge). The laser beam intensity is a Gaussian-shaped pulse. We consider a density such that n/ncr=25 (ncr is the critical density). The ponderomotive pressure due to the incident high-intensity laser radiation pushes the electrons at the target plasma surface, producing a sharp density gradient, which gives rise to a charge separation. The resulting electric field accelerates the ions. Two cases are considered, namely the case of a relatively thin target (about five skin depth) and the case of a much larger target. The evolution of the charge separation, the associated electric field and the formation of a neutral plasma jet ejected toward the rear side of the target differ in the two cases considered. In the case of a thin target, we observe the ion population accelerated to higher velocities. The absence of noise in the Eulerian Vlasov code allows a detailed representation of the phase-space structures of the distribution functions associated with the two cases considered, which shows substantial differences to be discussed in this paper.

Generation of an atomic beam by using laser ablation for isotope separation purposes

Atomic vapor laser isotope separation has been studied at the Institute for Advanced Studies for nuclear purposes since 1982, and recently it has been questioned about its potentialities for the aerospace area. Many applica- tions from nuclear propulsion to electricity generation and space navigation have been found, which justify the study of isotope separation for aerospace applications. 2ne of the Ney process, and the orst step for atomic vapor laser isotope separation, is the production of a neutral vapor jet. This paper discussed the potentiality of using laser ablation as a tool to generate neutral metal vapor jet for isotope separation purposes. The basis for the discussion is a set of experimental results obtained at the Institute for Advanced Studies. The experiments were described, the results were analyzed using basic theoretical treatment found in the literature, and it was concluded that laser ablation is a potential tool for the generation of a neutral vapor jet for atomic vapor laser isotope separation purposes.

Optical electron-beam diagnostics of free supersonic jet of nitrogen activated by electron-beam-generated plasma

Electron-beam-induced optical emission spectroscopy has been used for the first time to measure the rotational temperature and number density of gas in a free supersonic neutral nitrogen jet and in that activated by electron-beam plasma. The electron-beam plasma was generated by a low-energy electron beam at a distance of 10 mm downstream from the edge of a conical supersonic nozzle. For diagnostics of the activated jet, the spectrum of intrinsic optical emission of plasma was subtracted from the spectrum of emission induced by the probing electron beam in the activated jet. It was established that the rotational temperature in the activated jet is increased as compared to that in the neutral jet, while the density at the jet axis is decreased. The electron-beam activation of nitrogen in the jet leads to a 35% increase in the rotational temperature.