Aluminum Plasma Research Articles

Effect of polarization on spectroscopic characterization of laser produced aluminium plasma

Laser-induced breakdown spectroscopy (LIBS) is a well-established technique widely used in fundamental research and diverse practical fields. Polarization-resolved LIBS, a variant of this technique, aims to improve the sensitivity, which is a critical aspect in numerous scientific domains. In our recent work we demonstrated that the degree of polarization (DOP) in the emission depends on the spatial location and time in a nano second laser generated aluminium plasma1. Present study investigates the effect of polarized emission on the estimation of plasma parameters. The plasma parameters are estimated using the conventional spectroscopic methods such as Boltzmann plot and line intensity ratio for the estimation of electron temperature and Stark broadening for estimating the electron density. The estimated plasma temperature using Boltzmann plot method shows large errors in electron temperature for the locations where DOP is higher. However, the electron density estimated using the Stark width does not show such variation. The observed ambiguity in temperature estimation using the Boltzmann plot method appears to be a consequence of deviation from expected Maxwell Boltzmann distribution of population of the involved energy levels. These findings highlight the need of assessing the DOP of the plasma before selecting the polarization for PRLIBS or temperature estimation using Boltzmann plots in elemental analysis.

RHDLPP: A multigroup radiation hydrodynamics code for laser-produced plasmas

In this paper, we introduce the RHDLPP, a flux-limited multigroup radiation hydrodynamics numerical code designed for simulating laser-produced plasmas in diverse environments. The code bifurcates into two packages: RHDLPP-LTP for low-temperature plasmas generated by moderate-intensity nanosecond lasers, and RHDLPP-HTP for high-temperature, high-density plasmas formed by high-intensity laser pulses. The core radiation hydrodynamic equations are resolved in the Eulerian frame, employing an operator-split method. This method decomposes the solution into two substeps: first, the explicit resolution of the hyperbolic subsystems integrating radiation and fluid dynamics; second, the implicit treatment of the parabolic part comprising stiff radiation diffusion, heat conduction, and energy exchange. Laser propagation and energy deposition are modeled through a hybrid approach, combining geometrical-optics ray-tracing in sub-critical plasma regions with a one-dimensional solution of the Helmholtz wave equation in super-critical areas. The thermodynamic states are ascertained using an equation of state, based on either the real gas approximation or the quotidian equation of state (QEOS). For ionization calculations, the code employs a steady-state collisional-radiation (CR) model using the screened-hydrogenic approximation. Additionally, RHDLPP includes RHDLPP-SpeIma3D, a three-dimensional spectral simulation post-processing module, for generating both temporally-spatially resolved and time-integrated spectra and imaging, facilitating direct comparisons with experimental data. The paper showcases a series of verification tests to establish the code's accuracy and efficiency, followed by application cases, including simulations of laser-produced aluminium (Al) plasmas, pre-pulse-induced target deformation of tin (Sn) microdroplets relevant to extreme ultraviolet lithography light sources, and varied imaging and spectroscopic simulations. These simulations highlight RHDLPP's effectiveness and applicability in fields such as laser-induced breakdown spectroscopy, extreme ultraviolet lithography sources, and high-energy-density physics.

Prospective findings from the Dongfeng-Tongji cohort: Exposure to various metals, the expression of microRNA-4286, and the incidence of acute coronary syndrome

Mounting evidence suggests that metal/metalloid exposure is related to the adverse health effects. Our prior investigation revealed a positive relation between the plasma level of microRNA-4286 (miR-4286) and an increased risk of developing acute coronary syndrome (ACS). However, it is a lack of studies evaluating the connection between metal/metalloid exposure and miRNA expression on ACS. In the prospective Dongfeng-Tongji cohort, we performed a nested case-control study. A total of 480 ACS and 480 controls were carefully selected based on similar age, sex, and blood collection time. Using inductively coupled plasma mass spectrometry, we assessed the plasma concentrations of 24 different metals. Quantitative real-time polymerase chain reaction was used to analyze the plasma miR-4286. We examined the relations of plasma metals with miR-4286 levels, the incidence of ACS, and the potential interactions. Using the multivariate conditional logistic regression models, we observed that the adjusted odds ratios (95% confidence intervals [CI]) for incident ACS were 1.79 (1.03, 3.12; P-trend = 0.03), 0.60 (0.41, 0.87; P-trend = 0.008), and 0.66 (0.46, 0.93; P-trend = 0.02), when comparing the extreme tertiles of aluminum, rubidium, and selenium, respectively. There was a relation between the concentration of rubidium in plasma and a decrease in the level of plasma miR-4286 (percent difference [95% CI]: −13.36% [-22.74%, −2.83%]; P-trend = 0.01). Both multiplicative (P interaction = 0.009) and additive interactions (relative excess risk due to interaction [95% CI]: 0.82 [0.59, 1.06]) were noted in our observation regarding the relationship between plasma aluminum and miR-4286 in incident ACS. The findings indicated that plasma aluminum was positively while plasma rubidium and selenium were negatively linked to an increased risk of developing ACS. Plasma aluminum exposure and plasma miR-4286 expression might synergistically affect the incident ACS risk. Controlling aluminum exposure was important for ACS prevention, especially for individuals with high expression of plasma miR-4286.

Development of a planar ICP ion source for fusion based neutron generator

In this paper preliminary results of a new planar ICP ion source for neutron generator is investigated. This ion source has a cylindrical planar Aluminum plasma chamber. Set of Niobium permanent magnets have been arranged as multicusp geometry around the chamber to improve the plasma density and reduce the operational pressure. A copper made helical antenna has been used which is connected to the 2 kW 13.56 MHz radiofrequency power source including matching network. Preliminary results of ion beam measurements using 1 and 3 mm diameter apertures on plasma electrodes, represents improvement of ion current from μA range to mA with Helium operational gas. A primary result with Deuterium gas indicates that the ion current improves up to 7 mA by applying multicusp magnetic field around the plasma chamber at similar operational parameters with 1 kW of RF power. Theoretical and experiments are performed to regulate the optimum distance between plasma and the accelerating electrodes to have parallel deuteron ion beam at around 65 kV electrical potential between them. Accelerating electrode configuration which suppresses the secondary electron generated on the target surface is designed and fabricated based on the simulation results.

Development of laser-ablated aluminum plasma plume during the irradiation of laser pulse

In this paper, we theoretically simulate the dynamic evolution of plasma from the interaction between a nanosecond pulsed laser and aluminum targets. The self-luminous image of the plasma plume during the laser loading process was experimentally obtained using high-speed photography. Theoretical and experimental results demonstrated that the plasma shielding effect and plasma lateral expansion have a significant effect on the plasma plume. It will affect laser–target coupling and further affect the evolution of plasma plumes. The detonation wave contained in the early stage of the laser-induced plasma plume directly affects the subsequent shock wave.

Reconstruction and analysis of transient evolution images of laser-produced plasma plumes.

We introduce a method for the analysis and simulation of transient images of laser-produced plasma (LPP) plumes. This method comprises three steps: (i) calculating the two-dimensional distribution of plasma parameters using a radiation hydrodynamics model, (ii) constructing radiation paths through ray tracing, and (iii) solving the radiation transport equation along these paths. In our simulations, we have meticulously considered factors that could influence the imaging results, including the quantum efficiency to different radiation wavelengths, the imaging lens' transmittance, the target surface's reflectivity, and the absorption, emission, and scattering quantum effect of the detector processes occurring in the plasma. We applied this method to analyze and simulate the transient images of aluminum plasma plumes in a background air environment at a pressure of 2000 Pa. The results demonstrate that our method not only produces simulated images that align with experimental results but also provides a reliable distribution of plasma state parameters and clearly identifies the ion species radiating in different bands. Given its capability in transient image reconstruction and its adaptability as a tool for spectral simulation and analysis of LPPs, we believe this method holds significant potential for spectral diagnostics in fields such as laser-induced breakdown spectroscopy, extreme ultraviolet lithography sources, and high-energy-density physics, among others.

Edge lithography based on aluminum dry etching

Traditional nanolithography methods, such as electron beam or ion beam lithography, can be expensive and slow, limiting their applications. Edge lithography offers a promising alternative for efficiently and effectively creating nanoscale patterns using lower-cost lithography equipment with higher throughput. Our paper presents a new edge lithography technique to pattern fine structures with coarse patterns utilizing aluminum plasma dry etching without thin film deposition. The aluminum oxide layer generated on the sidewall of the Al structure during the etching process defines the final nanostructures. Our experiments show that this layer is formed through the oxidation of the aluminum layer itself, providing a simple and practical approach to creating complex nanostructures without additional steps or materials. In addition, using the non-switching pseudo-Bosch etching process, we transferred the nano-edge pattern formed in aluminum oxide into the silicon substrate. Our technique allows for cost-effective and efficient nanoscale patterning for various applications.

The generation of a fourth-harmonic probe and its application in Nomarski interferometry at Shengguang-II.

In this work, a design for the generation of a 4ω (263-nm) probe converted from a 1ω (1053-nm) laser is presented. The design is based on a beta-barium borate and potassium dihydrogen phosphate two-step frequency-conversion process. A suitable configuration for Nomarski interferometry based on the 4ω probe is proposed, for measuring the electron density of laser-produced plasmas. The signal-to-noise ratio of the output 4ω probe to 1ω and 2ω light after frequency quadrupling and harmonic separation is 103 with a 0.5 GW/cm21ω input but decreases to ∼102 at intensities below 0.1 GW/cm2. Additional noise suppression by a factor of 104 is achieved using filters before the interferometer recording camera. The spatial resolution of the diagnostic can reach 5.2 µm for a 10% modulation transfer function. An experiment validating the probe diagnostic system is conducted at the Shengguang-II laser facility. A clear interferogram of an aluminum plasma is obtained with 0.1 GW/cm2 input, suggesting a maximal electron density of about 2.5 × 1020 cm-3 as retrieved through an inverse-Abel transform. The design proposed in this paper is appropriate for a small laser device or a large laser facility that lacks a separate diagnostic beam, and it is an inexpensive solution as it requires small-aperture 1ω input at a relatively low intensity. All the key parameters necessary to implement the design are provided in detail, making it straightforward to reproduce or transplant the system for specific uses.

Four-framed X-ray imaging crystal spectrometer for time-resolved laser plasma diagnostics

X-ray imaging crystal spectrometers with high spectral and spatial resolutions are the important diagnostic tools for acquiring high-quality plasma information in the study of laser–matter interactions. In this paper we propose a new multi-channel imaging crystal spectrometer with coupling X-ray framing camera to record the dynamic evolution of a laser-induced plasma: a four-channel imaging mica crystal spectrometer with a spatial resolution of 40–60 μm for diagnosing the aluminum (Al) plasma targets was developed. Calibration experiments revealed that the spectral resolution is higher than 1700 at Al Kα3 characteristic lines (1496.4eV). Further, we established an aiming method based on the positioning ball and two monitoring CCDs. The optical design, mechanical design, and experimental measurements of the four-channel imaging mica crystal spectrometer are discussed.

Radiative cooling effects on reverse shocks formed by magnetized supersonic plasma flows

We study the structure of reverse shocks formed by the collision of supersonic, magnetized plasma flows driven by an inverse (or exploding) wire array with a planar conducting obstacle. We observe that the structure of these reverse shocks varies dramatically with wire material, despite the similar upstream flow velocities and mass densities. For aluminum wire arrays, the shock is sharp and well-defined, consistent with magneto-hydrodynamic theory. In contrast, we do not observe a well-defined shock using tungsten wires, and instead we see a broad region dominated by density fluctuations on a wide range of spatial scales. We diagnose these two very different interactions using interferometry, Thomson scattering, shadowgraphy, and a newly developed imaging refractometer that is sensitive to small deflections of the probing laser corresponding to small-scale density perturbations. We conclude that the differences in shock structure are most likely due to radiative cooling instabilities, which create small-scale density perturbations elongated along magnetic field lines in the tungsten plasma. These instabilities grow more slowly and are smoothed by thermal conduction in the aluminum plasma.

Numerical Simulation of the Interaction of High-Velocity Plasma Jets Injected in the Earth’s Ionosphere

The paper presents a numerical simulation of the dynamics of high-velocity aluminum plasma jets with multiple injection in the Earth’s ionosphere. Scenarios of single injection, counter injection, and collimation of plasma jets at a given convergence angle are considered. The gas-dynamic parameters of plasma formations and their optical characteristics are determined.

Average-atom Ziman resistivity calculations in expanded metallic plasmas: Effect of mean ionization definition.

We present calculations of electrical resistivity for expanded boron, aluminum, titanium, and copper plasmas using the Ziman formulation in the framework of the average-atom model. Our results are compared to experimental data, as well as to other theoretical calculations, relying on the Ziman and Kubo-Greenwood formulations, and based on average-atom models or quantum-molecular-dynamics simulations. The impact of the definition of ionization, paying particular attention to the consistency between the definition and the perfect free electron gas assumption made in the formalism, is discussed. We propose a definition of the mean ionization generalizing to expanded plasmas the idea initially put forward for dense plasmas, consisting in dropping the contribution of quasibound states from the ionization due to continuum ones. It is shown that our recommendation for the calculation of the quasibound density of states provides the best agreement with measurements.

Optical emission features of laterally colliding laser-produced plasmas at different ambient pressures

Optical emission characteristics of seed plasma and stagnation region of laterally colliding laser produced aluminium plasmas are investigated under various background gas pressures of air and argon ambient. The intensity of ionic and neutral emissions from seed plasma region increases with the increase of ambient pressure. Neutral emission from the stagnation region increases whereas the intensity of ionic emission decreases with the increase of ambient pressure. Decrease of collision rate between the seed plasmas results in the decrease of ionic emission from the interaction region. For higher inter seed plume separation, maximum spectral emission from stagnation region is observed at an intermediate pressure range of 10−2 mbar. Emission intensity and the life time of both ionic and neutral emission are greater in heavier Ar ambient. In the case of seed plasmas, the electron density decreases whereas the electron temperature increases with the increase of ambient gas pressure and is greater in Ar ambient. The variations of plasma parameters are quite less in stagnation region.

Effect of Al2O3 and MoS2 reinforcement on microstructure, mechanical, and wear properties of plasma sprayed aluminium hybrid composite coating

This study investigates the role of incorporating alumina (Al2O3) and molybdenum disulfide (MoS2) into an aluminium (Al) plasma sprayed coating on microstructure, mechanical, and wear properties. For this, we fabricated four different coatings with various compositions viz. Al,Al + 10 wt% Al2O3, Al+ 5 wt% MoS2, Al+ 10 wt% Al2O3 + 5 wt% MoS2 utilizing a plasma spraying. The microstructure analysis reveals that the reinforcements are distributed uniformly within the coating, and relative density of Al hybrid composite coating has enhanced significantly to 97.5%. Furthermore, mechanical properties like hardness and elastic modulus increased to 112.5% and 77.1%, respectively. Then, reinforcement of Al2O3 and MoS2 into the Al coating significantly reduces the wear rate and coefficient of friction of the coating as 45.5% and 72.3% respectively. These improved tribological properties of the coating can be accredited to the enhanced hardness and lubrication characteristics of the reinforcements. The findings suggest that incorporating both Al2O3 and MoS2 into an Al plasma sprayed coating can be a promising approach for improving the coating's microstructural, mechanical, and tribological properties, making it suitable for a variety of industrial applications.

Digital holographic measurement of electron temperature and density of laser-produced plasmas with an ultrashort laserpulse.

Holography, which can provide the information of phase as well as amplitude of a laser probe, could be a powerful method to diagnose the electron density and temperature of a plasma simultaneously. In this paper, digital holography with an ultrashort laser pulse is applied to diagnose laser-produced aluminum plasmas. Detailed analyses show that the reconstruction of the wave amplitude could be profoundly affected by the difference between the phase and group velocity of the ultrashort laser pulse in the plasma, which makes it a challenge to accurately reconstruct the amplitude in the case when ultrashort laser pulses are utilized for high-temporal resolution of holography.

Erratum

Microwave and Optical Technology LettersEarly View ERRATUMFree Access Erratum This article corrects the following: Determining the temperature of aluminum plasma produced by laser-induced breakdown spectroscopy based on its ultraviolet emission spectra Xinhao Wang, Guqing Guo, Xuanbing Qiu, Ting Gong, Xiaohu He, Chuanliang Li, Volume 65Issue 5Microwave and Optical Technology Letters pages: 1229-1234 First Published online: April 21, 2022 First published: 10 May 2023 https://doi.org/10.1002/mop.33757AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Erratum to “Determining the temperature of aluminum plasma produced by laser-induced breakdown spectroscopy based on its ultraviolet emission spectra”, Microw Opt Technol Lett. 2023; 65:1229-1234 by Xinhao Wang, Guqing Guo, Xuanbing Qiu, Ting Gong, Xiaohu He, Chuanliang Li. In the published article, there was an unintended error where the author's abbreviated name information was incorrect. The correct abbreviation for the author's name is Li, CL instead of Li, CAL. The full name of the author is Chuanliang Li. We apologize for the error. REFERENCE 1Wang X, Guo G, Qiu X, Gong T, He X, CL Li. Determining the temperature of aluminum plasma produced by laser-induced breakdown spectroscopy based on its ultraviolet emission spectra. Microw Opt Technol Lett. 2023; 65: 1229- 1234. doi:10.1002/mop.33283 Early ViewOnline Version of Record before inclusion in an issue ReferencesRelatedInformation

Kinetics analysis and enhancement mechanism of aluminum-enhanced plasma nitriding for 42CrMo steel

Aluminum-enhanced plasma nitriding (Al-PN) was developed by a complex treatment of electrolyzing aluminum nitrate and plasma nitriding (PN) for 42CrMo steel; the kinetics and enhancement mechanism was analyzed. Optical microscope and X-ray diffractometer were used to determine the microstructure and phases constituents of the samples. The results show that much thicker case depth is obtained, with hard phases of AlN and FexAl formed in the surface layer by Al-PN treatment, which brings about much harder surface layer and excellent wear resistance. The kinetics analysis shows that the diffusion coefficient is enhanced by Al-PN, and the diffusion activation energy is reduced from 100.531 kJ/mol by PN to 45.177 kJ/mol by Al-PN. The relationship between case depth, temperature T (K) and holding time t (s) is obtained as: dAl-PN = 1.17 × 10−5exp(−5434T)t. (753 K ≤ T ≤ 793 K). Finally, the verification tests confirmed that the developed kinetics agrees quite well with the measured values; therefore, it can be used to predict the case depth for a designed process parameters in practical applications.

Geometrical Analysis of the Stagnation Zone in Laterally Colliding Plasmas: Effects of Plasma Plume Separation and Ablating Target Material

The influence of an ablating target’s atomic mass on the development and growth of the interaction zone in laterally colliding plasmas has been investigated. As diagnostic tools, fast imaging and optical emission techniques were used to evaluate the characteristics of the seed plasma as well as the interaction zone created by different target materials (i.e., aluminum and silicon). The current findings show that the dynamical, spectral, and geometrical properties of the generated interaction zone are affected by the features of the ablated species and the geographical separation of the interacting plumes. The interaction of aluminum plume species results in a sharper, more intense, and more directed stagnation zone than that reported for silicon targets using a 450 nm filter. Furthermore, the investigation of the interaction area emission from both regions for aluminum (Al) and silicon (Si) plasma explains the variation in plasma properties in the stagnation zone. As a part of this work’s description, a comparative study of the dynamics and characteristics of the homogenous interaction region produced by colliding plasma plumes by laser ablation of flat Al and Si targets has been presented, which can provide deep insight into the characterization of colliding laser-produced plasma expansion and related physical and technical properties.

Spatio-temporal dynamics of anisotropic emission from nano-second laser produced aluminium plasma

We report the polarization of spectral emission from aluminium plasma generated using a ns laser. The results show an interesting behaviour of polarization flips with the plasma plume propagation direction.

Experimental and computational investigation into the hydrodynamics and chemical dynamics of laser ablation aluminum plasmas.

Laser ablation plasma chemistry is governed by a complex interplay between hydrodynamic plasma-gas mixing processes, thermodynamics, and rapid high-temperature chemical reactions. In this work, we investigate the gas-phase oxidation chemistry of ns-laser ablation aluminum plasmas in air using optical spectroscopy combined with advanced multi-physics modeling. Experimental measurements demonstrate the formation of AlO in the plasma plume as early as 1 μs while computational results reveal that several AlxOy species are distributed in the periphery of the plume at even earlier times (<20 ns) in the presence of large temperature gradients and strong shockwaves. Interactions with the ablation crater during rapid plume expansion are shown to initiate vortex formation, followed by mixing dynamics that work to pull AlO into the vortices to react with gas-phase Al to form Al2O. Oxygen and several aluminum oxides are simultaneously pulled up through the stem of the fireball, encouraging further intermixing between reacting species and enhanced molecular formation. This work concludes that chemical dynamics in laser ablation plasmas is driven by diffusion processes, concentration gradients, and plume hydrodynamics while strong shockwaves generated during laser ablation do not impede chemical reactions.