Line Intensities Research Articles

Investigating chloride-induced corrosion in reinforced concrete structures using Laser-Induced Breakdown Spectroscopy

Reinforced concrete structures face significant annual expenditures in combating rebar corrosion, with chloride penetration identified as a major contributor. This study employs laser-induced breakdown spectroscopy (LIBS) to quantitatively predict the chloride-induced corrosion rate in such structures. Eighty samples, characterized by known chloride content (ranging from 0% to 1.0%), underwent controlled corrosion processes with predetermined degrees measured as bar weight loss. The investigation included two cement types, Type I and Type V, along with samples incorporating pozzolanic materials (FA, SF, and GGBFS,) in addition to plain OPC samples. LIBS was subsequently employed to detect chlorine presence in each concrete sample, recording the corresponding intensity of the chlorine line. After the initial data acquisition, peak analysis was performed to identify the dominant spectral peaks, ensuring that the most relevant signals were isolated. Following this, the intensity of the chloride emission line from the LIBS spectrum was recorded and correlated with its corresponding chloride signal, establishing a quantitative relationship between the LIBS output and chloride presence. A model was then developed to link the LIBS signal intensity to its corresponding chloride concentration in the sample. In parallel, the corrosion rate associated with each specific chloride concentration was measured and then linked to the LIBS-derived chloride concentrations, creating a framework that ties the LIBS output to the actual rebar degradation within the concrete. Comparisons with previous studies demonstrated superior conformity of the developed models. The study also presents optimized parameters for the LIBS setup. Notably, results indicated a high correlation between LIBS intensity and chloride concentration, with the developed model accurately predicting the degree of corrosion.

Abstract A046: Development of a scoring system to classify HER2 protein expression in circulating tumor cells through immunofluorescence following isolation using Parsortix® instruments

Abstract Background. HER2 testing through immunohistochemistry (IHC) is routinely performed on tissue biopsy samples from metastatic breast cancer (MBC) patients, resulting in a HER2 score that is used in patient stratification and treatment decisions. However, tissue biopsy is invasive, with little opportunity for re-examination while liquid biopsy is minimally invasive and allows monitoring of disease progression through recurrent sample collection. This study aimed to establish an assay (Research Use Only) allowing scoring of HER2 protein expression in circulating tumor cells (CTCs), by immunofluorescence (IF) staining, using cancer cell lines of known HER2 expression. Method. Cultured cancer cell lines with HER2 expression comparable to tissue samples (i.e. HER2 0, 1+, 2+ and 3+ by IHC score) were used in this study (SKBR3 [3+], HCC1954 [3+], SKOV-3 [2+/3+], ZR-75-1 [2+], MCF-7 [0 – 1+] and Hs 578T [0]). Cultured cancer cells were spun onto CellKeep™ slides and stained with ANGLE’s Portrait HER2 IF panel, comprising a nuclear dye, an anti-HER2 antibody, epithelial, mesenchymal and leukocyte markers. Slides were imaged on a BioView Allegro Plus, a platform equipped with artificial intelligence for automated imaging, CTC candidate identification and reporting. The workflow was implemented using samples from 5 MBC patients with known HER2 IHC scores, whose blood was drawn into Streck Cell-Free DNA tubes and processed on ANGLE's Parsortix® instrument, a marker-independent microfluidic device which isolates CTCs based on size and deformability, before being stained with the Portrait HER2 assay. The cohort is being expanded and currently includes three HER2 0 and two HER2 3+ patients as diagnosed by tissue IHC. Results. By observing mean fluorescence intensity (MFI) of each cancer cell line reported to be reflective of each IHC score, thresholds were set to establish a protein scoring system. 95%, 95% and 91% of SKBR3, HCC1954 and SKOV-3, respectively, fell in the 3+ class, 83% of ZR-75-1 fell in the 2+ class, 69% of MCF-7 fell in the 1+ class and 25% and 89% of MCF-7 and Hs 578T, respectively, fell in the 0 class. ≥1 CTC were found in all 5 subjects (mean=405, median=146), with 60% donors presenting mesenchymal CTCs, 20% epithelial CTCs and 20% epithelial and mesenchymal CTCs. HER2+ CTCs were found in both HER2 3+ donors, but not in the HER2 0 donors. HER2+ CTCs from both donors fell in the 3+ class based on MFI, despite one donor receiving Herceptin treatment (1 CTC) and the other being treatment naïve (435 CTCs). Conclusion. This study showed it is possible to establish a HER2 protein scoring system using cultured cancer cell lines stained with the Portrait HER2 assay and demonstrates the potential utility of liquid biopsy in tracking HER2 status. This scoring system will be applied to CTCs isolated from an extended cohort of MBC patients with known tissue biopsy HER2 IHC results to test the robustness of the system and assess concordance of CTC and tissue biopsy scores. FISH will be performed on the samples from MBC patients to confirm results. Citation Format: Alex Young, Laila Vlietinck, Bethan Edwards, Liam Cook, Chassidy Johnson, Mariacristina Ciccioli, Anne-Sophie Pailhes-Jimenez. Development of a scoring system to classify HER2 protein expression in circulating tumor cells through immunofluorescence following isolation using Parsortix® instruments [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A046.

Evidence for clustering in iron-doped strontium titanate

Electron paramagnetic resonance spectra of iron-doped strontium titanate have been studied at room temperature for Fe concentrations between 0.2 and 1.0 mol%. The linewidth of the line associated with the 1/2 ↔ –1/2 transition of Fe3+ changes very little with with Fe concentration and the line intensity goes through a maximum between 0.40 and 0.60 mol%. The results suggest that the solid solution of Fe3+ in SrTiO3 is not random, but exhibits significant clustering effects.

Time-dependent metal ionization and the persistence of collisionally excited emission lines in the diffuse ionized gas of star forming galaxies

Abstract We extend our time-dependent hydrogen ionization simulations of diffuse ionized gas to include metals important for collisional cooling and diagnostic emission lines. The combination of heating from supernovae and time-dependent collisional and photoionization from midplane OB stars produces emission line intensities (and emission line ratios) that follow the trends observed in the Milky Way and other edge-on galaxies. The long recombination times in low density gas result in persistent large volumes of ions with high ionization potentials, such as O iii and Ne iii. In particular, the vertically extended layers of Ne iii in our time-dependent simulations result in [Ne III] 15μm/[Ne II] 12μm emission line ratios in agreement with observations of the edge-on galaxy NGC 891. Simulations adopting ionization equilibrium do not allow for the persistence of ions with high ionization states and therefore cannot reproduce the observed emission lines from low density gas at high altitudes.

Influence of species kinetics on discharge characteristics in oxygen helicon plasma

Abstract Oxygen (O2) helicon plasmas in multiple wave modes were excited by a right-helical antenna with an upper metal endplate at low pressure. Mode transitions were observed at increasing input power or magnetic field, characterized by obvious jumps of plasma parameters. Blue Core appears at high magnetic fields (~700 G) and input powers (~1700 W), with a large radial gradient of plasma density, ion line intensity, and electron temperature. Emission spectra demonstrate that the blue lights originate from O II lines. We found that the intensity ratio of O II to O I of Blue Core in O2 is lower by one order than that in N2 or Ar despite their similar ionization rates and plasma densities in Blue Core area. A high-temperature B-dot probe together with a waveform fitting procedure was used to present the measured oscillating waveforms of m =+1 helicon waves, showing distinct wave structures of different eigenmodes. Cavity mode resonance is suggested to be responsible for the formation of standing waves of discrete eigenmodes. A pressure balance model was developed to estimate the species densities around the central area in different modes, showing massive dissociation of O2 molecules and high density of O atoms locally, so that O2 helicon plasma behaves a species feature of monatomic gas discharge. The obviously low intensity of O II lines compared to O I lines of Blue Core in O2 is related to the quite high excitation threshold of O+ ions (~30 eV) although electron density and temperature are relatively high. The combined effects of dispersed reaction energy distribution, massive molecule dissociation and negative ion creation are considered to be the main causes for requirement of much higher RF power and magnetic field for Blue Core formation in O2 helicon plasma than that in Ar. The calculated radial profile of power deposition and the captured plasma morphology confirm that the dominant central electron heating is the essential reason for the large radial gradients of plasma density and electron temperature which contributes to the serious neutral depletion and Blue Core formation.

The CH3D Absorption Spectrum Near 1.58 μm: Extended Line Lists and Rovibrational Assignments

Monodeuterated methane (CH3D) contributes greatly to absorption in the 1.58 μm methane transparency window. The spectrum is dominated by the 3ν2 band near 6430 cm−1, which is observed in natural methane and used for a number of planetary applications, such as the determination of the D/H ratio. In this work, we analyze the CH3D spectrum recorded by high-sensitivity differential absorption spectroscopy in the 6099–6530 cm−1 region, both at room temperature and at 81 K. Following a first contribution to this topic by Lu et al., the room-temperature line list is elaborated (11,189 lines) and combined with the previous 81 K list (8962 lines) in order to derive about 4800 empirical lower-state energy values from the ratio of the line intensities measured at 81 K and 294 K (2T-method). Relying on the position and intensity agreements with the TheoReTS variational line list, about 2890 transitions are rovibrationally assigned to twenty bands, with fifteen of them being newly reported. Variational positions deviate from measurements by up to 2 cm−1, and the band intensities are found to be in good agreement with measurements. All the reported assignments are confirmed by Ground-State Combination Difference (GSCD) relations; i.e., all the upper-state energies (about 1370 in total) have coinciding determinations through several transitions (up to 8). The energy values, determined with a typical uncertainty of 10−3 cm−1, are compared to their empirical and variational counterparts. The intensity sum of the transitions assigned between 6190 and 6530 cm−1 represents 76.9 and 90.0% of the total experimental intensities at 294 K and 81 K, respectively.

Enhancing silicon spectral emission in LIBS using Tesla coil discharge

Laser-induced breakdown spectroscopy (LIBS) is a powerful technique for elemental analysis, offering rapid analysis, minimal sample preparation, wide elemental coverage, and portability. To enhance the detection sensitivity of LIBS, increasing the spectral emission intensity is crucial. This paper explores the use of Tesla coil (TC) discharge as an alternative to spark discharge in silicon LIBS. The study examines the influence of TC discharge on both time-integrated and time-resolved spectra, with and without TC discharge; the corresponding electron temperature and density are obtained. The results show that TC discharge significantly amplifies the spectral intensity, improving signal sensitivity in LIBS analysis. Specifically, in the laser energy range from 7.4 to 24.0 mJ, TC discharge increased the average spectral line intensities of Si (II) 385.60 nm and Si (I) 390.55 nm by factors of 8.4 and 5.1, respectively. Additionally, the average electron temperature and density were enhanced by approximately 3.2% and 4.2%, respectively, under TC discharge. The advantages of TC discharge include higher energy deposition, extended discharge duration, reduced electrode erosion, and enhanced safety. This research contributes to advancing LIBS technology and expanding its applications in various fields.

Measurements of line parameters for 12C16O2 near λ = 1.05 μm by cavity ring-down spectrometer

The absorption spectra of 12C16O2 within the wavenumber range of 9358–9648 cm−1 have been precisely measured using a continuous-wave cavity ring-down spectrometer at room temperature. Employing synthetic gas mixtures comprising carbon dioxide, nitrogen, and argon, the line parameters, including line intensities and self-, N2- and Ar- broadening coefficients have been retrieved in the 2003r-00001 (r = 1,2,3) bands. This retrieval process was facilitated by a multi-spectral fitting program that utilizes Voigt line profiles. A comparative analysis of our measured line intensities and self-broadening coefficients with those present in established databases, such as HITRAN2020, CDSD296, AMES-2021, and HITEMP2010, has been conducted. The line intensities and self-broadening coefficients for 12C16O2 deviate by an average of less than 1 % from the values reported in the HITRAN2020 database. The J-dependence of N2- and Ar- broadening coefficients has been investigated by comparing this work with experimental results and theoretical predictions from other vibrational bands. This research offers important experimental references for the improvement of computational models and the exploration of Venus and Mars.

Study of soft X-ray radiation of plasma produced by interaction of laser radiation with copper targets at the “Kanal-2” facility

As part of the work on creating an x-ray microscope, experimental and theoretical studies of laser plasma of solid copper targets in the soft x-ray range were carried out. With a laser pulse duration of 2.5 ns (FWHM), the power density of the Nd:glass laser on the target is varied in the range 0.8 × 1013–4.2 × 1013 W/cm2. Experimental results demonstrated the presence of intense plasma emission in spectral ranges of water and carbon windows, and the number of photons of the most intense lines was calculated. Spatio-temporal studies of copper plasma have demonstrated intense emission in the wavelength range shorter than 15 Å, and the images of plasma emission in time-integrated and linear sweep modes are shown. The simulations of the interaction of the specified laser radiation flux with copper targets were carried out taking into account the transfer of self-radiation in plasma. The non-local thermodynamic equilibrium optical properties of the plasma were used. As a result of calculations, profiles of density, temperature, electron thermal conductivity flux, emissivity of plasma, and self-radiation flux were obtained. The calculated spectrum of the outgoing radiation is consistent with that obtained at the experiment.

Surface cleaning with atmospheric pressure plasma jet investigated by in-situ optical emission spectroscopy and laser-induced breakdown spectroscopy

Cleaning of surfaces with atmospheric pressure plasma jet (APPJ) is investigated by in-situ optical emission spectroscopy (OES) and laser-induced breakdown spectroscopy (LIBS). The APPJ device operates a spark discharge of kW power in Argon gas flow resulting in a powerful plasma jet expanding into air. For cleaning experiments samples are coated with lubricant layers of 1.1 to 7.1 µm thickness. Light collected at the sample surface during APPJ treatment is analyzed spectroscopically and used to monitor the cleaning process. LIBS chemical imaging delivers spatial cleaning profiles of plasma treated surfaces. From measured emission intensities of CN molecular band and Na atomic line the cleaning efficiencies for carbon and Na containing contaminants are determined. The power of APPJ plasma generator, distance between sample and jet nozzle, scan speed, and Argon gas flow are varied to optimize the surface treatment. Thermal and non-thermal processes contribute to cleaning. For the carbon containing contaminant thermal processes are dominating (∼90 %) while also non-thermal processes (∼30–45 %) are relevant for the Na containing component. A cleaned surface area per time from 0.3 to 10 cm2/s is investigated. Cleaning efficiency up to 95 % is obtained highlighting the potential of APPJ surface cleaning under ambient conditions.

Theoretical investigation of iodine plasma through detailed electron impact excitation cross-section calculations and collisional-radiative model analysis

Abstract In the present study, we consider the electron impact excitation of neutral iodine and its application in developing a collisional-radiative model for plasma diagnostics of iodine plasma. Electron impact excitation cross- sections are calculated using fully relativistic distorted wave theory. The required atomic structure calculations for iodine are carried out using the relativistic multi-configuration Dirac-Fock method. The excitation energies obtained are reported and compared with values from the NIST database. The electron impact excitation cross-sections are calculated from the ground (5p5 2P3/2) and first- excited state (5p5 2P1/2) to the several upper fine structure levels. Our cross- section results align well with previous studies, reported by Ambalampitiya et al. [Atoms, 9, 103, 2021] using the Breit-Pauli B-spline R-matrix method. Further calculated cross-section results are incorporated into the collisional-radiative model. Our model also includes electron impact ionization, de-excitation, three- body recombination, and radiative decay. We validate our model using emission spectra from inductively coupled iodine plasma. For this purpose, we used the recorded intensities for the emission lines, 486.23 nm, 511.92 nm, 523.45 nm, 589.40 nm, and 608.24 nm are compared with those obtained from our model to calculate electron temperature and electron density of the iodine plasma.

Forecasts and Statistical Insights for Line Intensity Mapping Cross-correlations: A Case Study with 21 cm × [C ii]

Intensity mapping—the large-scale mapping of selected spectral lines without resolving individual sources—is quickly emerging as an efficient way to conduct large cosmological surveys. Multiple surveys covering a variety of lines (such as the hydrogen 21 cm hyperfine line, carbon-monoxide rotational lines, and [C ii] fine-structure lines, among others) are either observing or will soon be online, promising a panchromatic view of our Universe over a broad redshift range. With multiple lines potentially covering the same volume, cross-correlations have become an attractive prospect, both for probing the underlying astrophysics and for mitigating observational systematics. For example, cross-correlating 21 cm and [C ii] intensity maps during reionization could reveal the characteristic scale of ionized bubbles around the first galaxies, while simultaneously providing a convenient way to reduce independent foreground contaminants between the two surveys. However, many of the desirable properties of cross-correlations in principle emerge only under ideal conditions, such as infinite ensemble averages. In this paper, we construct an end-to-end pipeline for analyzing intensity mapping cross-correlations, enabling instrumental effects, foreground residuals, and analysis choices to be propagated through Monte Carlo simulations to a set of rigorous error properties, including error covariances, window functions, and full probability distributions for power-spectrum estimates. We use this framework to critically examine the applicability of simplifying assumptions such as the independence and Gaussianity of power-spectrum errors. As worked examples, we forecast the sensitivity of near-term and futuristic 21 cm × [C ii] cross-correlation measurements, providing recommendations for survey design.

Integration of ML methods with CR model-based optical diagnostic for the estimation of electron temperature in Ga laser produced plasma

Accelerated diagnostic of plasma plays a significant role in controlling and optimizing plasma-mediated processing, particularly for plasma with higher temporal and spatial gradients, such as laser produced plasma (LPP). In the present work, two advanced machine learning (ML) algorithms, random forest regression, and gradient boosting regression are integrated with noninvasive collisional radiative (CR) model-based optical diagnostics to facilitate accurate diagnostics. A comprehensive fine-structure resolved CR model framework is developed by incorporating our consistent cross section data obtained from the Relativistic Distorted Wave method [Suresh et al., “Fully relativistic distorted wave calculations of electron impact excitation of gallium atom: Cross sections relevant for plasma kinetic modelling,” Spectrochim. Acta B: At. Spectrosc. 213, 106860 (2024)]. An extensive dataset of CR model simulated intensities is created to train and test the ML methods. The present CR model is applied to characterize the Gallium LPP coupling with the optical emission spectroscopic measurements of Guo et al. [“Time-resolved spectroscopy analysis of Ga atom in laser induced plasma,” Laser Phys. 19, 1832–1837 (2009)] at different delay times. Further, a detailed correlation study of the line intensity ratios is performed to observe the qualitative behavior of the plasma parameters. The electron temperature results obtained from the CR model, ML, and line ratio methods were compared and found to be in excellent agreement. Overall, the present study demonstrates diagnostic approaches that can benefit the LPP community significantly by providing a rapid understanding of the plasma behavior across various operating conditions.

Magnetic Field Alignment Relative to Multiple Tracers in the High-mass Star-forming Region RCW 36

We use polarization data from SOFIA HAWC+ to investigate the interplay between magnetic fields and stellar feedback in altering gas dynamics within the high-mass star-forming region RCW 36, located in Vela C. This region is of particular interest as it has a bipolar H ii region powered by a massive star cluster, which may be impacting the surrounding magnetic field. To determine if this is the case, we apply the histogram of relative orientations (HRO) method to quantify the relative alignment between the inferred magnetic field and elongated structures observed in several data sets such as dust emission, column density, temperature, and spectral line intensity maps. The HRO results indicate a bimodal alignment trend, where structures observed with dense gas tracers show a statistically significant preference for perpendicular alignment relative to the magnetic field, while structures probed by the photodissociation region (PDR) tracers tend to align preferentially parallel relative to the magnetic field. Moreover, the dense gas and PDR associated structures are found to be kinematically distinct such that a bimodal alignment trend is also observed as a function of line-of-sight velocity. This suggests that the magnetic field may have been dynamically important and set a preferred direction of gas flow at the time that RCW 36 formed, resulting in a dense ridge developing perpendicular to the magnetic field. However, on filament scales near the PDR region, feedback may be energetically dominating the magnetic field, warping its geometry and the associated flux-frozen gas structures, causing the observed preference for parallel relative alignment.

SOFIA/upGREAT far-infrared spectroscopy of bright rimmed pillars in IC 1848

Using the upGREAT instrument on SOFIA, we imaged the [C II] 158 µm fine structure line emission in bright-rimmed pillars located at the southern edge of the IC 1848 H II region, and carried out pointed observations of the [O I] 63 and 145 µm fine structure lines toward selected positions. The observations are used to characterize the morphology, velocity field, and the physical conditions in the G1–G3 filaments. The velocity-resolved [C II] spectra show evidence of a velocity shift at the head of the brightest G1 filament, possibly caused by radiation pressure from the impinging UV photons or the rocket effect of the evaporating gas. Archival Herschel PACS and SPIRE observations imply H2 column densities in the range 1021 –1022 cm−2 , corresponding to maximum visual extinction AV ≃ 10 mag, and average H2 volume density of ≃4500 cm−3 in the filaments. The [C II] emission traces ∼17% of the total H2 column density, as derived from dust SED fits. Photon-dominated region models are unable to explain the observed line intensities of the two [O I] fine structure lines in IC 1848, with the observed [O I] 145 µm line being too strong compared to the model predictions. The [O I] lines in IC 1848 are overall weak and the signal-to-noise ratio is limited. However, our observations suggest that the [O I] 63/145 µm intensity ratio is a sensitive probe of the physical conditions in photon-dominated regions such as IC 1848. These lines are thus excellent targets for future high-altitude balloon instruments, less affected by telluric absorption.

Toward electron temperature profiles in hot-dense plasmas from x-ray spectral ensembles

High repetition rate laser systems enable new strategies for diagnosing plasma behavior with large datasets. Here, we define an ensemble technique that relies on randomized targeting of x-ray tracer micro-stripes. On each shot, a high-intensity laser pulse is focused on a solid target with Ti tracer stripes embedded in an Al foil, randomly targeting a micro-stripe, a portion of a stripe, or a gap between stripes. High-resolution, time-integrated x-ray spectrometers capture line emission from the portion of the micro-stripe that is heated to sufficiently high electron temperatures. Accumulation of many such cases is used to construct ensemble distributions of x-ray line intensities that encompass all relative offsets of the laser focus to the micro-stripe centers. Synthetic intensity distributions are likewise generated using collisional-radiative modeling. Bayesian fitting of modeled to measured intensity distributions establishes the most likely radial temperature profiles, enabling comparison to hydrodynamic models and calling into question the cylindrical symmetry of these micro-stripe-embedded systems. Ensemble techniques have significant potential for high-energy-density plasma diagnostics, especially with the advent of high repetition rate experiments.

Mechanism of metastable krypton atom preparation via laser-induced ionization

Preparation of metastable Kr atoms in the 5s[3/2]2 level via laser-induced ionization has been achieved. The temporal evolution of the intensity of Kr atomic spectral lines at 760.15 nm, 811.29 nm, and 431.96 nm was used to elucidate the production mechanisms of metastable Kr atoms. These mechanisms primarily involve two processes: the “excitation + radiation” process, dominated by multiphoton excitation and initial plasma-induced electron impact excitation, and the “ion-electron recombination” process, governed by avalanche ionization. The decay time constants of Kr atomic spectral lines, corresponding to the “excitation + radiation” and “ion-electron recombination” processes respectively, were obtained experimentally under both strong and weak ionization conditions. The experiments revealed delay in preparations of metastable Kr atoms between these two processes. To reduce the loss of metastable Kr atoms and effectively utilize their peak concentration, we drew inspiration from metastable rare gas lasers and proposed the “cycling” idea to keep metastable Kr atoms produced by these two processes as synchronized as possible. We used 811.29 nm laser to excite metastable Kr atoms generated rapidly during the “excitation + radiation” stage to the 5p[5/2]3 level. The Kr atoms returned to the 5s[3/2]2 level through spontaneous radiation, merging with metastable Kr atoms that were slowly produced during the “ion-electron recombination” stage. We hope that the “cycling” idea can shorten the delay in preparations of metastable Kr atoms from both processes and enhance the peak concentration of metastable Kr atoms. However, the experimental results didn't meet expectations, as we observed a decrease in the 811.29 nm fluorescence after laser excitation, attributed to the accumulation of 5p[5/2]3 level Kr atoms. These atoms undergo energy pooling to populate the 4d’[3/2]1 and 5d[7/2]3 levels, followed by absorption of 811.29 nm laser energy leading to photoionization. Reducing the concentration of 5p[5/2]3 level Kr atoms helps mitigate the reionization issue.

Electron-impact excitation data for W2+ in support of tungsten spectroscopy and re-deposition measurements for magnetically-confined plasmas

Abstract To better understand plasma wall interactions involving tungsten, accurate atomic structure and electron-impact driven collisional processes for near-neutral ion stages of tungsten are required. Complementing existing work on neutral and singly ionised tungsten, atomic structure and collisional calculations for W2+ electron-impact excitation have been completed. These excitation calculations are an important component of S/XB coefficients for near-neutral charge states, which may be used to spectroscopically infer re-deposition of tungsten at the plasma-solid boundary of fusion relevant devices. With W2+ in particular having emission lines that can be observed at ultraviolet (UV) wavelengths, while higher charge states of tungsten are unlikely to have lines possible to observe outside of the vacuum UV range. The atomic structure was generated using the General-purpose Relativistic Atomic Structure Package (GRASP0), implementing the Multi-configuration Dirac Fock approach. This structure was the basis for a subsequent Dirac R-matrix electron-impact excitation calculation to provide Maxwellian averaged rate coefficients. A synthetic spectrum was generated from this data using a collisional-radiative model to predict the strongest W III spectral lines and these lines were compared to emission from the Compact Toroidal Hybrid (CTH) plasma device. Several of the strongest W III lines are observed in CTH and agree well with the modelled line wavelengths and intensities, a table of these lines is provided that could be observed in other devices.

CII] line intensity mapping the epoch of reionization with the Prime-Cam on FYST. II. CO foreground masking based on an external catalog

The Fred Young Submillimeter Telescope (FYST) line intensity mapping (LIM) survey will measure the power spectrum (PS) of the singly ionized carbon 158 $ fine-structure line CII to trace the appearance of the first galaxies that emerged during and right after the epoch of reionization (EoR, $6<z<9$). We aim to quantify the contamination of the (post-)EoR CII LIM signal by foreground carbon monoxide (CO) line emission ($3 < J_ up < 12$) and assess the efficiency to retrieve this CII LIM signal by the targeted masking of bright CO emitters. Using the IllustrisTNG300 simulation, we produced mock CO intensity tomographies based on empirical star formation rate-to-CO luminosity relations. Combining these predictions with the CII PS predictions of the first paper of this series, we evaluated a masking technique where the interlopers are identified and masked using an external catalog whose properties are equivalent to those of a deep Euclid survey. Prior to masking, our CII PS forecast is an order of magnitude lower than the predicted CO contamination in the 225 GHz ( CII emitted at $z=6.8-8.3$) band of the FYST LIM survey, at the same level in its 280 GHz ( CII emitted at $z=5.3-6.3$) and 350 GHz ( CII emitted at $z=4.1-4.8$) bands, and an order of magnitude higher in its 410 GHz ( CII emitted at $z=3.4-3.9$) band. For our fiducial model, the optimal masking depth is reached when less than 10<!PCT!> of the survey volume is masked at 350 and 410 GHz but around 40<!PCT!> at 280 GHz and 60 <!PCT!> at 225 GHz. At these masking depths we anticipate a detection of the CII PS at 350 and 410 GHz, a tentative detection at 280 GHz, whereas at 225 GHz the CO signal still dominates our model. In the last case, alternative decontamination techniques will be needed.

Laser-induced plasma analysis of ammonia-oxygen and ammonia-oxygen-enriched-air flames at elevated pressures

This study employed Laser-induced breakdown spectroscopy (LIBS) to measure the fuel-oxidizer ratio (FOR) of ammonia combustion with oxygen-enriched air and pure oxygen flames at elevated pressures (100 - 300 kPa). The correlations between the spectral line intensity ratios of nitrogen (N), hydrogen (H), oxygen (O), and equivalence ratio were used to quantify the FOR of flames at various pressures. The effect of pressure on the stability and precision of the calibration profiles for the elemental intensity ratios in flames was investigated. It was observed that the H/O correlation decreases with pressure increase for both ammonia flames. N/O correlations decrease with elevated pressure for the ammonia-oxygen flame. Furthermore, the nitrogen (NII) spectral emission lines at 568 nm and 595 nm were used to estimate the plasma temperature, while the hydrogen (Hα) line at 656 nm was used for electron number density measurements.