Article
Materials Science, Multidisciplinary
Keita Katayama, Toshiki Kinoshita, Ren Okada, Hiroshi Fukuoka, Takehito Yoshida, Minoru Yaga, Tamao Aoki-Matsumoto, Ikurou Umezu
Summary: In this study, the behavior of laser-induced plumes after collision was investigated by colliding silicon and germanium in a helium background gas. The results showed that the counter-propagating shock wave played a crucial role in the backward movement and mixing of the plumes under certain conditions. Additionally, the pressure and type of background gas also had an influence on the degree of mixing of the plumes.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2022)
Article
Chemistry, Physical
Emily H. H. Kwapis, Jacob W. W. Posey, Enrique Medici, Kira Berg, Ryan W. W. Houim, Kyle C. C. Hartig
Summary: Laser ablation plasma chemistry in aluminum plasmas is investigated using optical spectroscopy and multi-physics modeling. It is found that aluminum oxides are formed in the plasma plume due to temperature gradients and strong shockwaves. The interaction between the ablation crater and the plume leads to vortex formation and enhanced molecular formation. This study concludes that diffusion processes, concentration gradients, and plume hydrodynamics drive the chemical dynamics in laser ablation plasmas, and strong shockwaves do not impede chemical reactions.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Physics, Applied
S. S. Harilal, E. J. Kautz, M. C. Phillips
Summary: We present the spatiotemporal evolution of emission and absorption signatures of Al species in a nanosecond laser-produced plasma (LPP). The measurements were conducted using time-of-flight (TOF) emission and laser absorption spectroscopy, providing kinetic information of the excited state and ground state populations. Multiple peaks were observed in the temporal profiles of the emission and absorption signatures, corresponding to different spatial locations and times. The absorption spectra were used to measure linewidths, column density, and kinetic temperature, while the emission spectra were used to measure excitation temperature. The combination of TOF and spectral measurements offers a more complete understanding of the spatiotemporal dynamics of the LPP.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Optics
Emily H. Kwapis, Maya Hewitt, Kyle C. Hartig
Summary: Shadowgraphic measurements combined with gas-dynamics theory were used to study the shock physics of nanosecond laser ablation of cerium metal targets. Time-resolved shadowgraphic imaging was performed to measure the propagation and attenuation of the laser-induced shockwave in different background pressures, revealing that higher ablation laser irradiances and lower pressures lead to stronger shockwaves with higher propagation velocities. The Rankine-Hugoniot relations were also employed to estimate the properties of the shock-heated gas, predicting larger pressure ratios and higher temperatures for stronger laser-induced shockwaves.
Article
Chemistry, Physical
Jiangyou Long, Ziyu He, Deyi Ou, Yajun Huang, Pengchao Wang, Qinglei Ren, Xiaozhu Xie
Summary: In this study, the formation of dense nanostructures on silicon carbide surfaces through femtosecond laser micromachining was investigated. The morphology and distribution of these nanostructures were found to be influenced by laser parameters, and the formation mechanism was observed through microscopic imaging.
SURFACES AND INTERFACES
(2022)
Article
Optics
Emil H. Kwapis, Maya Hewitt, Kyle C. Hartig
Summary: Shadowgraphic measurements combined with gas-dynamics theory are used to investigate the physics of shockwaves generated by nanosecond laser ablation of cerium metal targets. Time-resolved shadowgraphic imaging is employed to measure the propagation and attenuation of the laser-induced shockwave through air and argon atmospheres at different background pressures. The Rankine-Hugoniot relations are also used to estimate the properties of the shock-heated gas behind the shock front.
Article
Spectroscopy
Hantian Zhang, Hao Sun, Yi Wu, Qianhong Zhou
Summary: This study focuses on the influence of gas pressure on the dynamic characteristics of laser-induced plasma, revealing that higher gas pressure leads to greater electron number density and electron temperature within the central of LIP and a faster decay rate. A torus structure in LIPs is generated during the later stage of plasma decay, significantly affecting the distribution of electron number density, electron temperature, and the intensity of plasma emission.
SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY
(2021)
Article
Spectroscopy
Emily H. Kwapis, Eliel Villa-Aleman, Kyle C. Hartig
Summary: This research aims to investigate the influence of atmospheric conditions and oxidation reactions on the spectroscopic characteristics of laser-induced plutonium surrogate plasmas. Time-resolved spectra of nanosecond laser ablation cerium plasmas were measured in various atmospheres containing different concentrations of oxygen. The results showed that in oxygen-rich environments, the presence of CeO decreased from around 60 & mu;s to 50 & mu;s, and significant growth of CeO molecular emission bands was observed. The formation and depletion of CeO in the laser-produced plasma were further studied using integrated intensities of the CeO D1-X1 transition and strong atomic Ce peaks.
SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY
(2023)
Article
Chemistry, Multidisciplinary
Song Cai, Juan Wang, Qi Li, Wenhao Liu, Guoqi He, Zheying Zhang, Yi Ji
Summary: Plasma characteristic models were established in cylindrical coordinates based on the plasma expansion characteristics of pulsed laser processing. Experimental and calculation results verified the correctness of the models and provided theoretical guidance and process optimization for laser machining of materials.
Article
Physics, Applied
Elizabeth J. Kautz, Mark C. Phillips, Sivanandan S. Harilal
Summary: In this study, laser-induced fluorescence (LIF) was utilized to enhance emission signals from plasma generated by ultrafast laser filaments on an Al 6061 alloy target. This approach effectively reduced self-reversal features and improved detection sensitivity for standoff and remote element and isotope detection. The findings highlight the potential of LIF for boosting signal-to-noise ratio in filament-induced breakdown spectroscopy applications.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Thermodynamics
Shiyu Li, Jinxin Wang, Xiao Wang, Yongpan Cheng, Wei-Cheng Yan
Summary: This study uses a numerical model to investigate the mechanism of laser ablation for space debris removal. The model incorporates various physical processes involved in laser ablation, such as heating, melting, and evaporation of the target material (Aluminum), formation of plume and plasma, and plasma shielding. Validation of the model is achieved by comparing simulated results with experimental data, demonstrating the accuracy of the model in describing laser ablation processes. The study systematically examines the effects of laser irradiance, wavelength, and pulse width on laser ablation. Continuous laser ablation and the influence of laser pulse time interval are also explored.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Optics
Siqi He, Qi Min, Maogen Su, Haidong Lu, Yanhong Wu, Shiquan Cao, Duixiong Sun, Denghong Zhong, Chenzhong Dong
Summary: We developed a post-processing optical imaging model based on two-dimensional axisymmetric radiation hydrodynamics, benchmarked with laser-produced Al plasma optical images obtained via transient imaging. The model reproduces the emission profiles of a laser-produced Al plasma plume in air at atmospheric pressure, and clarifies the influence of plasma state parameters on radiation characteristics. It solves the radiation transport equation on the real optical path, mainly used to study the radiation of luminescent particles during plasma expansion. The model provides outputs such as electron temperature, particle density, charge distribution, absorption coefficient, and spatio-temporal evolution of the optical radiation profile, aiding in element detection and quantitative analysis of laser-induced breakdown spectroscopy.
Article
Optics
Yang Ou, Jianjun Wu, Yu Zhang, Jian Li, Yuanzheng Zhao
Summary: This paper investigates the influence of different alloy particles on the plume characteristics of polymeric material under laser irradiation. The results show that each alloy particle can contribute to the stable and massive formation of the ablation plume. Among them, Al-Si doping exhibits the best propulsion performance.
OPTICS AND LASER TECHNOLOGY
(2022)
Article
Physics, Multidisciplinary
R. H. H. Scott, K. Glize, L. Antonelli, M. Khan, W. Theobald, M. Wei, R. Betti, C. Stoeckl, A. G. Seaton, T. D. Arber, D. Barlow, T. Goffrey, K. Bennett, W. Garbett, S. Atzeni, A. Casner, D. Batani, C. Li, N. Woolsey
Summary: The study used a subignition scale laser and a shallow-cone target to investigate laser-plasma interactions, finding that convective stimulated Raman scatter was the dominant instability under certain conditions. Experimental evidence of two plasmon decay was only observed when the density scale length was reduced. The study also found that hot electrons had electron temperatures between 35 and 45 keV, with laser energy-coupling to hot electrons at 1%-2.5%.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Applied
Elizabeth J. Kautz, David J. Senor, Sivanandan S. Harilal
Summary: The study focused on the emission of deuterium (2 H alpha) in plasmas generated from femtosecond laser ablation of a Zircaloy-4 target with varying focusing lens positions. Changes in emission intensity, plume morphology, and crater dimensions were observed. The results showed that adjusting the laser focal point position can significantly impact the emission intensity and plasma characteristics.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
S. S. Harilal, E. J. Kautz, M. C. Phillips
Summary: We present the spatiotemporal evolution of emission and absorption signatures of Al species in a nanosecond laser-produced plasma (LPP). The measurements were conducted using time-of-flight (TOF) emission and laser absorption spectroscopy, providing kinetic information of the excited state and ground state populations. Multiple peaks were observed in the temporal profiles of the emission and absorption signatures, corresponding to different spatial locations and times. The absorption spectra were used to measure linewidths, column density, and kinetic temperature, while the emission spectra were used to measure excitation temperature. The combination of TOF and spectral measurements offers a more complete understanding of the spatiotemporal dynamics of the LPP.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Optics
Ryan T. Rhoades, Reagan R. D. Weeks, Seth E. Erickson, Caroline Lecaplain, Sivanandan S. Harilal, Mark C. Phillips, R. Jason Jones
Summary: The broadband and high-resolution absorption spectra of molecular cerium oxide (CeO) are obtained using dual-comb spectroscopy in a laser-produced plasma. Simultaneous measurements of Ce and CeO are used to investigate the time-resolved dynamics of the system. The high spectral resolution allows for the simultaneous detection of numerous closely spaced rotational transitions in complex CeO bands.
Article
Nanoscience & Nanotechnology
Elizabeth J. Kautz, Sten Lambeets, Jacqueline Royer, Daniel E. Perea, Sivanandan S. Harilal, Arun Devaraj
Summary: Compositional partitioning during uranium alloy oxidation was studied using complementary ex situ-in situ atom probe tomography. The results revealed the formation of hypostoichiometric uranium oxide under all environmental conditions. Redistribution of molybdenum, hydrogen, carbon, and silicon impurities was observed, affecting the composition of the oxide film.
SCRIPTA MATERIALIA
(2022)
Article
Physics, Applied
Reagan R. D. Weeks, Yu Zhang, Sivanandan S. Harilal, Mark C. Phillips, R. Jason Jones
Summary: Dual-comb spectroscopy (DCS) is a novel diagnostic tool for analyzing excitation temperatures and column densities in laser-produced plasmas (LPPs). In this study, DCS was used to measure the excitation temperatures and column densities of Nd, Gd, and Fe in a multielement alloy. The results showed that the excitation temperatures of Nd I and Gd I were consistent at all time-delays, while the Fe I temperature was higher and the column density ratios varied with delay.
JOURNAL OF APPLIED PHYSICS
(2022)
Review
Physics, Multidisciplinary
S. S. Harilal, M. C. Phillips, D. H. Froula, K. K. Anoop, R. C. Issac, F. N. Beg
Summary: This article provides an overview of optical diagnostic tools frequently used for the characterization of laser-produced plasmas (LPPs), focusing on the low to moderate laser intensity regime. The review emphasizes the techniques, assumptions, and challenges associated with these diagnostic tools.
REVIEWS OF MODERN PHYSICS
(2022)
Article
Physics, Fluids & Plasmas
Yingchao Huang, Sivanandan S. Harilal, Abdul Bais, Amina E. Hussein
Summary: Optical emission spectroscopy, known as LIBS, is a rapid soil analysis technique. However, challenges like matrix effects and quantification issues need further study, especially for heterogeneous samples like soils. Advancements in machine learning can overcome these challenges and enhance the potential of LIBS in soil analysis.
IEEE TRANSACTIONS ON PLASMA SCIENCE
(2023)
Editorial Material
Physics, Fluids & Plasmas
Sivanandan S. S. Harilal, Uri Shumlak, Justin Little
Summary: ICOPS is an annual conference that brings together plasma physics researchers to discuss various applications of plasma science and technology. It is organized by the PSAC of the IEEE NPSS.
IEEE TRANSACTIONS ON PLASMA SCIENCE
(2023)
Article
Physics, Applied
M. P. Polek, E. J. Kautz, T. Ahmed, B. R. Kowash, F. N. Beg, S. S. Harilal
Summary: The ion emission properties of laser-produced plasmas were investigated with varying laser intensities and angles. The ion profiles consist of multiple peaks and each peak follows a unique trend as a function of laser intensity, angle, and distance. Simple analytical models can explain the ion properties, and the variations in ion velocity and density agree with theoretical models of acceleration, expansion, and plasma flow.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Optics
Mark C. Phillips, Elizabeth J. Kautz, Sivanandan S. Harilal
Summary: High-resolution tunable laser absorption spectroscopy is used to measure time-resolved absorption spectra for six neutral uranium transitions in a laser-produced plasma. Analysis of the spectra shows that kinetic temperatures are similar for all six transitions, but excitation temperatures are higher than kinetic temperatures from 10-100 microseconds, indicating departures from local thermodynamic equilibrium.
Article
Physics, Fluids & Plasmas
Elizabeth J. J. Kautz, Mark C. C. Phillips, Prasoon K. K. Diwakar, Alla Zelenyuk, Sivanandan S. S. Harilal
Summary: The kinetics of ion and neutral atom emissions in nanosecond laser-produced plasmas were investigated for different metal targets and an alloy. It was found that the most probable velocities of ions and atoms decrease with increasing atomic mass. The velocities of ions from the alloy target represent a weighted average of all ions. Both ions and atoms exhibit decreased velocities with increasing heat of vaporization and melting temperature. The kinetic energies of neutral atoms from pure metal targets have some variability with atomic mass, whereas those from the alloy target are more similar, possibly due to collisions between species in the Knudsen layer.
PHYSICS OF PLASMAS
(2023)
Article
Spectroscopy
Elizabeth J. Kautz, Mark C. Phillips, Sivanandan S. Harilal
Summary: We measured the time-resolved emission spectroscopic signatures of Ta, TaO, and TaN from a laser-produced plasma. Varying the O2/N2 percentages in the gaseous environment, we observed that Ta oxide emission is more prominent in later stages of plasma evolution, while strong atomic emission is present in the early stages in air. The emission intensity of TaO increases, and its peak intensity appears earlier with increasing O2 availability. Additionally, we found that the presence of O2 favors TaO formation over TaN in the plasma chemistry.
SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY
(2023)
Article
Chemistry, Physical
Elizabeth J. Kautz, Alla Zelenyuk, Bharat Gwalani, Matthew J. Olszta, Mark C. Phillips, Manuel J. Manard, Clare W. Kimblin, Sivanandan S. Harilal
Summary: The role of ambient oxygen gas in laser ablation plumes on molecular and nanoparticle formation and agglomeration was studied. The presence of O2 impacts the emission spectra, cluster size, and agglomeration behavior of nanoparticles. These findings are important in understanding debris formation in an explosion event.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Optics
Elizabeth J. Kautz, Annie Xu, Ajay V. Harilal, Mathew P. Polek, Andrew M. Casella, David J. Senor, Sivanandan S. Harilal
Summary: Laser induced breakdown spectroscopy is a promising method for the rapid analysis of Li and its isotopes. However, challenges arise from spectral broadening, fine and hyperfine structures, and self-reversal effects. This study investigates the impact of ambient gases on line broadening and self-reversal of Li isotopes in laser produced plasmas. The results show that lower pressures and optimized plasma conditions can improve the accuracy of isotopic analysis.
Article
Chemistry, Physical
Elizabeth J. Kautz, Alla Zelenyuk, Bharat Gwalani, Mark C. Phillips, Sivanandan S. Harilal
Summary: This study investigates the evolution from gas-phase oxidation to nanoparticle and agglomerate formation in nanosecond laser-produced plasmas of a multi-principal element alloy target. The results highlight the importance of the target composition in the formation of gas-phase molecules, as well as the morphology, composition, and structure of nanoparticles and agglomerates formed.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Physics, Fluids & Plasmas
Elizabeth J. Kautz, Mark C. Phillips, Alla Zelenyuk, Sivanandan S. Harilal
Summary: The temporal evolution of atoms and molecules in a laser-produced plasma from metal targets was investigated using optical emission spectroscopy. The results showed that the partial pressure of O-2 strongly influences spectral features and molecular formation in laser-produced plasmas.
PHYSICS OF PLASMAS
(2022)