Electron Density Measurements Research Articles

Design and development of a single-laser 2D Thomson scattering measurement system for TS-6 merging tokamak/magnetic reconnection experiments

Nd:YAG Thomson scattering diagnostics is reliable measurement of electron temperature and density, but its 2D extension conventionally needs as many polychromators as measuring points and as many lasers as measuring paths. To reduce the numbers and costs, we designed and developed a single-laser 2D measurement system by use of multiple reflection and time-of-flight of laser light. A single laser pulse reflects between mirrors on both sides of the vacuum vessel and makes seven round trips, which enables measurement at m × 7 points with only m polychromators and a single laser. Here, we present the design to satisfy the resolution required for TS-6 merging tokamak and magnetic reconnection experiments and the system development, especially the time-separation of scattered light signals from different points with time-of-flight delays. The measured Thomson scattering signals from 7 × 2 points and the measured Raman scattered signals from points in four laser paths indicate the feasibility of Thomson scattering measurement at m × 4 points.

Nanocrystal Agglomerates of Curcumin Prepared by Electrospray Drying as an Excipient-Free Dry Powder for Inhalation.

Curcumin has shown beneficial effects on pulmonary diseases with chronic inflammation or abnormal inflammatory responses, including chronic obstructive pulmonary disease, asthma, and pulmonary fibrosis. Clinical applications of curcumin are limited due to its chemical instability in solution, low water solubility, poor oral bioavailability, and intestinal and liver first-pass metabolism. Pulmonary delivery of curcumin can address these challenges and provide a high concentration in lung tissues. The purpose of the current work was to prepare a novel inhalable dry powder of curcumin nanocrystals without added excipients using electrospray drying (ED) with improved dissolution and aerosolization properties. ED of curcumin was performed at 2 and 4% w/v concentrations in acetone. Physicochemical properties of the formulated powders were evaluated by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), density and powder flow measurements, and in vitro dissolution. The in vitro deposition studies were conducted using next-generation impactor (NGI) and aerosol performance and aerodynamic particle size parameters were calculated for prepared formulations. ED could produce agglomerates of nanocrystals with a size of about 500 nm at an acceptable yield of about 50%. PXRD and FTIR data revealed that prepared nanocrystals were in a stable crystalline state. The bulk and tapped density of prepared agglomerates were in the range appropriate for pulmonary delivery. Formed nanocrystals could significantly improve the dissolution rate of water-insoluble curcumin. The optimized formulation exhibited acceptable recovered dose percentage, high emitted dose percentage, optimum mean mass median aerodynamic diameter, small geometric standard deviation, and high fine-particle fraction that favors delivery of curcumin to the deep lung regions. The ED proved to be an efficient technique to prepare curcumin nanocrystals for pulmonary delivery in a single step, at a mild condition, and with no surfactant.

Validating the simulation of beam-ion charge exchange in MAST Upgrade

Simulation of the impact of charge-exchange (CX) reactions on beam ions in the Mega Amp Spherical Tokamak (MAST) Upgrade was compared to measurements carried out with a fission chamber (neutron fluxes) and a fast ion deuterium-alpha (FIDA) diagnostic. A simple model was developed to reconstruct the outer-midplane neutral density based on measurements of deuterium-alpha emission from edge neutrals, and on Thomson scattering measurements of electron density and temperature. The main computational tools used were the ASCOT orbit-following code and the FIDASIM code for producing synthetic FIDA signals. The neutral density reconstruction agrees qualitatively with SOLPS-ITER modelling and yields a synthetic passive FIDA signal that is consistent with measurement. When CX losses of beam ions are accounted for, predicted neutron emission rates are quantitatively more consistent with measurement. It was necessary to account for CX losses of beam ions in simulations to reproduce the measured passive FIDA signal quantitatively and qualitatively. The results suggest that the neutral density reconstruction is a good approximation, that CX with edge neutrals causes significant beam-ion losses in MAST Upgrade, typically 20% of beam power, and that the ASCOT fast-ion CX model can be used to accurately predict the redistribution and loss of beam ions due to CX.

Post-midnight irregularities in equator and its adjacent regions of topside ionosphere obtained by the CSES satellite

The post-midnight irregularities in equator and its adjcent regions, which have remained least explored so far, are investigated using the in situ electron density (Ne) measurements from 2019 to 2021 obtained by the China Seismo-Electromagnetic Satellite (CSES) in the topside ionosphere. The followings are salient points of our findings: 1) Equatorial and low latitude post-midnight irregularities are distributed along the dip equator, exhibiting a wavenumber 4 longitude variation pattern and a seasonal variation pattern characterized by peaks in summer and winter and valleys in spring and autumn during low solar activity (LSA) period in the topside ionosphere, 2) The longitude variation pattern of post-midnight irregularities aligns with that of the background Ne, with irregularities concentrated at the peaks of background Ne, 3) The occurrence rate of post-midnight irregularities increases significantly with higher solar flux, which can be attributed to the rapid increase in the background Ne under LSA conditions. Additionally, the growth rate of occurrence rate varies across different longitudes, with the Pacific and the Atlantic longitudes standing out as prominent regions, and 4) Post-midnight irregularities in the topside ionosphere may have two possible origins. One is irregularities generated at the lower altitudes that drift upward into the topside ionosphere, while the other is the irregularities generated directly in the topside ionosphere. The latter is supported by the presence of conditions conducive to irregularity generation in the topside ionosphere during midnight hours in LSA period. Given the scarcity of research on post-midnight irregularity compared to post-sunset irregularity, further investigations are essential to fully comprehend their generation mechanisms. The abundance of post-midnight Ne measurements from the CSES satellite offers a valuable opportunity for this research, which can enhance our understanding of post-midnight ionospheric dynamics, and their variations with solar activity.

Investigating the Effects of Cold Plasma on Cancer Cell Migration in the Presence of a Static Magnetic Field

Cold plasma is used in a wide range of applications [1]–[3] One of the primary uses of plasma is in the field of medicine. Moreover, many techniques have been suggested to enhance plasma performance, among which the inclusion of an external static magnetic field is one [4], [5]. This paper used a low-power (20-watt) RF 13.56 MHz plasma to investigate the effect of cold plasma on cancer cells' migration rate in the presence of a static magnetic field. The result of the scratch healing assay is shown in Figure 1 (Ⅰ and Ⅱ). The results are evaluated after 24 hours. Figure 1 (Ⅰ-A) is before plasma treatment (control), (Ⅰ-B) is without treatment, (Ⅰ-C) is 15 seconds of plasma treatment, and (Ⅰ-D) is plasma and SMF treatment. The area of free space in the created gap has been evaluated by image processing software. The percentage of free space compared to the total space is specified in the diagram (Figure1-Ⅱ). As shown in the figure, the empty space for the state where the plasma is combined with the magnetic field is twice the state of the plasma alone. One of the main components of plasma that changes the presence of a magnetic field is the density and temperature of electrons in cold plasma. The electron temperature was evaluated based on the Boltzmann plot method, and the electron density measurement was calculated using the Saha-Boltzmann equation (figure 1-Ⅲ). The Boltzmann diagram is drawn using the used plasma spectrum, which was used in the previous work [6]. The calculation indicates that the electron temperature Te and electron density ne is estimated as 1.04 eV and for the absence of SMF, and 1.24 eV and for the presence of SMF, respectively Although several factors are involved in the effect of plasma, in this work, the temperature and electron density of the plasma were evaluated. Because apart from the direct impact on the target, the electron also affects the density of the ions. The findings indicate that the presence of a stationary magnetic field in close proximity to a plasma significantly regulated the migratory rate of cancer cells.Figure 1. (Ⅰ) scratch healing assay, (Ⅱ) percentage of gap for treatments, (Ⅲ) electron temperature calculation with Boltzmann plot.[1] S. Padureanu et al., “Non-Thermal Plasma-Activated Water: A Cytogenotoxic Potential on Triticum aestivum,” Agronomy, vol. 13, no. 2, 2023, doi: 10.3390/agronomy13020459.[2] V. Ioannou and S. Laizet, “Numerical investigation of plasma-controlled turbulent jets for mixing enhancement,” Int. J. Heat Fluid Flow, vol. 70, no. October 2017, pp. 193–205, 2018, doi: 10.1016/j.ijheatfluidflow.2018.02.008.[3] L. Guo et al., “Mechanism of virus inactivation by cold atmospheric-pressure plasma and plasmaactivated water,” Appl. Environ. Microbiol., vol. 84, no. 17, 2018, doi: 10.1128/AEM.00726-18.[4] X. Cheng et al., “Enhancing cold atmospheric plasma treatment of cancer cells by static magnetic field,” Bioelectromagnetics, vol. 38, no. 1, pp. 53–62, 2017, doi: 10.1002/bem.22014.[5] R. Mehrabifard, H. Mehdian, K. Hajisharifi, and E. Amini, “Improving Cold Atmospheric Pressure Plasma Efficacy on Breast Cancer Cells Control-Ability and Mortality Using Vitamin C and Static Magnetic Field,” Plasma Chem. Plasma Process., vol. 40, no. 2, pp. 511–526, Nov. 2020, doi: 10.1007/s11090-019-10050-5.[6] R. Mehrabifard, Z. Kabarkouhi, F. Rezaei, K. Hajisharifi, H. Mehdian, and E. Robert, “Physical understanding of the static magnetic field’s synergistic enhancement of cold atmospheric pressure plasma treatment,” Apr. 2023, Accessed: Sep. 21, 2023. [Online]. Available: https://arxiv.org/abs/2304.05833v1 Figure 1

High temporal resolution of pedestal dynamics via machine learning on density diagnostics

At the Joint European Torus, the reference diagnostic to measure electron density is Thomson scattering. However, this diagnostic has a low sampling rate, which makes it impractical to study the temporal dynamics of fast processes, such as edge localized modes. In this work, we use machine learning to predict the density profile based on data from another diagnostic, namely reflectometry. By learning to transform reflectometry data into Thomson scattering profiles, the model is able to generate the density profile at a much higher sampling rate than Thomson scattering, and more accurately than reflectometry alone. This enables the study of pedestal dynamics, by analyzing the time evolution of the pedestal height, width, position and gradient. We also discuss the accuracy of the model when applied on experimental campaigns that are different from the one it was trained on.

Ground and Space-based response of the ionosphere during the geomagnetic storm of 02–06 November 2021 over the low-latitudes across different longitudes

The strong geomagnetic storm of class G3 that occurred on 03 November 2021 (Dst min = −118 nT, Kp = 8) was the first of this class recorded during the ascending phase of solar cycle 25. In this study, we examined the response of the ionosphere during the geomagnetic storm period from 02–06 November 2021 using the Total Electron Content (TEC) observations from a chain of Global Navigation Satellite System (GNSS) receiver stations in five longitudinal sectors i.e, Asian, East-African, West-African, South-American, and Pacific-west sectors, in the low-latitudes and space-based Swarm satellite electron density, Ne and TEC measurements. The Rate of Change of TEC Index (ROTI) was derived from the ground and space based TEC measurements to examine the occurrence of ionospheric irregularities. The Rate of change of electron density index (RODI) was also derived from Swarm Ne measurements to identify the occurrence of ionospheric irregularities at Swarm altitudes. A positive ionospheric storm effect was observed in all the longitudinal sectors considered in this study. A clear hemispherical asymmetry, with higher VTEC in the northern hemisphere was observed. The determining factors for ionospheric responses to this storm are; local time of the storm’s onset, local time of storm’s minimum SYM-H, and changes in thermospheric O/N2 ratio. These geomagnetic storm effects were discussed in terms of the Prompt Penetration Electric Field (PPEF) storm induced wind lifting effect and Disturbance Dynamo Electric Field (DDEF). The geomagnetic storm inhibited the occurrence of ionospheric irregularities in all the sectors, during the main phase, except for three IGS receiver stations in South American sector. Overall, a longitudinal dependence of the enhancement/inhibition of ionospheric irregularities was observed. The generation of post-sunset irregularities was attributed to the local time occurrence of maximum ring current, PPEF and DDEF.

The Plasma In Situ Detection on China’s Space Station Wentian Module: Instrument Description and First Results

The plasma in situ detector is a multi-sensor package designed to in situ measure the bulk parameters of the local ionospheric plasma. The plasma in situ detector is comprised of three sensors: Langmuir probe (LP), retarding potential analyzer (RPA) and ion drift meter (IDM). LP measures electron density and temperature. RPA measures ion density, temperature and ion horizontal velocity. IDM measures the transverse horizontal component of the ram velocity. The plasma in situ detector has been installed outside the wentian module cabin, and the boom has been successfully deployed which extends the spherical sensor of LP beyond the sheath of the cabin. RPA and IDM were installed at the front of the experiment package, with the horizontal axis direction along the forward flight direction of the space station. This paper discusses the general performance characteristics of the in situ detector, the functional performance of each sensor, and initial results of some classical ionospheric features being observed.

The microwave dielectric properties of the low‐temperature firing BaZnP2O7 ceramics with Co2+ substitution

AbstractIn this study, the microwave dielectric properties of Co2+‐substituted BaZnP2O7 ceramics prepared through conventional solid‐state synthesis were investigated. X‐ray diffraction, Rietveld refinement, energy‐dispersive spectroscopy, and Raman spectroscopy all indicated that BaZn1−xCoxP2O7 ceramics sintered at 875°C were composed of a single phase. The lattice strain and crystallite size were estimated using Williamson–Hall (W–H) method. Both the scanning electron microscopy images and density measurements showed that Co2+ ions had an effect on the grain growth and densification of ceramics. The microwave dielectric properties were influenced by the intrinsic and extrinsic factors that varied with the increase of x value. An optimal performance (εr = 7.62, Q × f = 600 45 GHz, and τf = −74 ppm/°C) was achieved at x = .01. The porosity and relative density played a significant role in the dielectric constant εr: the denser the ceramic structure, the larger the dielectric constant. The Q × f and τf values were negatively correlated with the full width at half maximum of the Raman vibrational peak at approximately 1049 cm−1. Moreover, the Q × f value was improved compared to that of the undoped BaZnP2O7 ceramics. Therefore, cobalt ion substitution is an effective strategy to enhance the performance of microwave dielectric ceramics.

Effect of chemical vapor infiltration on the flexural properties of C/C-SiC composites prepared by the precursor infiltration pyrolysis method

Carbon/carbon-silicon carbide (C/C-SiC) composites were prepared by impregnation, hot-pressing with curing, carbonization at 800 oC and high-temperature heat treatment (800-1600 oC) using a 2D laminated carbon cloth as the reinforcing filler, and furfurone resin mixed with silicon, carbon from furfurone resin and SiC powders as the matrix. The effects of the addition of the three powders as well as subsequent chemical vapor infiltration (CVI) by methane on the density, microstructure and bend strength of the composites were investigated by scanning electron microscopy, density measurements, X-ray diffraction and mechanical testing. Both the SiC powders formed by the reaction at 1 600 oC between the added Si and C particles and the added SiC powder, play a role in the reinforcement of the materials. In three-point bending, the composites had a pseudoplastic fracture mode and showed interlaminar cracking. After 10 h CVI with methane, pyrolytic carbon was formed at the interface between some of the carbon fibers and the resin carbon matrix, which produced maximum increases in the density and flexural strength of the composites of 4.98% and 38.86%, respectively.

Molecular docking, drug-likeness and DFT study of some modified tetrahydrocurcumins as potential anticancer agents

The present study utilized molecular docking and density functional theory (DFT) approaches, and ADMET (absorption, distribution, metabolism, excretion, and toxicity) properties to investigate the binding interactions, reactivity, stability, and drug-likeness of curcumin (1), tetrahydrocurcumin (2), and tetrahydrocurcumin derivatives (3–6) as potential anti-cancer agents. MGL (Molecular Graphic Laboratory) and Discovery Studio Visualizer (DSV) software employed for docking studies. Pharmacokinetic and pharmacodynamic (ADME-Tox) analyses were conducted using SwissADME and pKCSM web servers. Total Electron Density (TED) measurements identified molecular adsorption sites, considering various factors, including quantum chemical characteristics, to assess compound effectiveness using DFT method implanted in the Gaussian software. The binding energy (Eb) from docking simulations was used to evaluate inhibitory potential. ADMET analysis suggested favorable oral bioavailability and pharmacokinetics for all studied substances, excluding compound 4. DFT and docking investigations highlighted compounds 1, 2, and 6 as optimal scaffolds for drug design based on in silico screening tests.

Evaluation of electron density measurements of Swarm and CSES satellites for using in ionospheric studies

Evaluation of electron density measurements of Swarm and CSES satellites for using in ionospheric studies

Surface Modification of Ti-Nb Alloy in Alkaline Solution to Enhance Bioactivity

Titanium alloys, especially titanium-niobium alloy have been reported as a potential biomaterial with good biocompatibility and non-toxicity. However, there is a lack of studies in alkaline surface treatment of new beta titanium alloy fabricated by vacuum arc melting (VAM) and powder metallurgy (PM) technique with high addition of niobium percentage. The purpose of this research was to examine the feasibility of surface modification on new beta Ti-40wt% Nb alloy in sodium hydroxide solution in order to form bioactive alkaline titanate layer. The characterization involved in this study is X-ray diffraction analysis (XRD), scanning electron microscope (SEM), microhardness, density measurement and optical microscope (OM). Development of amorphous alkaline titanate layer consisted of titanium hydrate, sodium titanate and oxide mixture of titanium oxide, niobium, niobium oxide were revealed by XRD. SEM shows titanate hydrogel layer form on Ti alloy PM thicker than on Ti alloy VAM. Microhardness and density measurement for Ti alloy VAM is greater than Ti alloy PM. OM shows porous surface on Ti alloy PM compare to VAM. This research suggests that the formation of sodium titanate layer on the surface of Ti-Nb alloy enhance bioactivity with better osteointegration and present higher formation of apatite which is crucial for the desired biomedical implant.

Joint measurement of electron density, temperature, and emission spectrum of Nd:YAG laser-produced tin plasma

We present the results of joint measurements of electron density (ne), temperature (Te), and emission spectra of an Nd:YAG-driven tin plasma. Collective Thomson scattering provides space- and time-resolved ne and Te data during drive laser irradiation, and extreme ultraviolet (EUV) emission spectra, which is space-resolved in the target normal, are measured using a flat-field grazing incidence spectrometer (GIS). As the distance from the target increased, the emission intensity quickly decreases, and the peaks of the spectra gradually shift to longer wavelengths. This can be explained by the rapid decrease in ne, and thus, self-absorption, with an increase in distance. We obtain the EUV spectra by calculating the transfer of photons along the line-of-sight of the GIS, using theoretical emissivity and opacity, and applying the measured spatial distribution of ne and Te. The results quantitatively demonstrate that the self-absorption effect is significant; the emission from the core regions is mostly reabsorbed by the surrounding plasma. The calculated spectra are compared with the measured spectra. While good agreement is achieved in the spectral region of 13.3 and 15.3 nm, considerable differences are found in the 12.5–13 and 15.5–17.5 nm region. The results demonstrate the significance of this joint measurement for further validation of the atomic process model considering self-absorption effect, which is critical for the future high-density, solid laser-driven EUV source.

Performance evaluation of IRI-Plas 2017 model with ionosonde data measurements of ionospheric parameters

This study presents an evaluation of the performance of the International Reference Ionosphere Model augmented with the Plasmasphere (IRI Plas 2017) from the Addis Ababa Ionosonde Station, Ethiopia, for measuring ionospheric parameters at geographic (9.00o N, 38.70o E) and geomagnetic (0.16o N, 110.44o E) location on selected days of 2014. During comparison hourly and daily variability of the ionospheric parameters of the electron density profile (Neh), maximum electron density (NmF2) and maximum height (hmF2) measurements are considered. When evaluating the IRI Plas model using ionosonde data, the percentage deviation and correlation coefficient (R) were used as measures of IRI Plas model performance. In general, the overall results of the study show that the IRI Plas 2017 model mostly overestimates at most altitudes and hours of electron density measurements. The IRI Plas model has an acceptable fit with the ionosonde electron density measurements at altitudes of 100 km–200 km, mostly during the hours between 03LT and 09 LT and 15 LT–21 LT, while the model biases in other altitudes and hours with overestimates or underestimates in the ionosonde electron density measurements. The IRI-Plas 2017 model has a good correlation after midnight and around midday hours, with about ±2% point deviation from the ionosonde electron density measurement. The model has a high percentage deviation value for electron density measurements, mostly between altitudes of 200 km and 450 km and during early nighttime and before midnight hours. IRI-Plas model measurements of NmF2 and hmF2 are mostly underestimated from the ionosonde data during the nighttime (21 LT–09 LT) and overestimated during the daytime (09 LT–21 LT). The NmF2 values measured with the model are more consistent with ionosonde values than hmF2 values.

On the In Situ Observations of Irregularities During Rocket Flights From Thumba for Different Geophysical Conditions and the Associated Causative Mechanisms

AbstractElectron density and Neutral Wind (ENWi) probe and/or Langmuir probe were flown on three different rocket flights from equatorial station Thumba (8.5°N, 77°E), during daytime, eclipse time, and post sunset time respectively, of low solar activity period, to study ionization irregularities in the E region of the ionosphere. The spectral characteristics observed using the payloads were analyzed during the three different rocket flights. The 15 January 2010 solar eclipse event and “SOUREX 1” wind and electron density measurements confirm the validity of the wind shear theory for equatorial regions during the eclipse and post sunset periods, when electrojet is weak, using wind and electron density irregularity measurements from the same instrument (ENWi) for the first time. The spectral indices in the range of −1.2 to −1.78 and the strong wind shear due to gravity wave winds during the eclipse time as well as the post sunset time, confirm the role of neutral turbulence in the generation of irregularities in the 95–112 km altitude region. The spectral index of −2.0 to −2.7 and the presence of irregularities in the negative gradient regions establishes the role of wind‐driven gradient drift instability (GDI) in generating irregularities during the SOUREX 1 post sunset flight for altitudes below 93 km. Further, the role of gradient drift instability in triggering ionization irregularities during the daytime on 14 January 2010 is unraveled by the spectral index of −2.03 and the presence of irregularities in the positive gradient regions alone.

Accelerating σ-Bond Metathesis at Sn(II) Centers.

Molecular main-group hydride catalysts are attractive as cheap and Earth-abundant alternatives to transition-metal analogues. In the case of the latter, specific steric and electronic tuning of the metal center through ligand choice has enabled the iterative and rational development of superior catalysts. Analogously, a deeper understanding of electronic structure-activity relationships for molecular main-group hydrides should facilitate the development of superior main-group hydride catalysts. Herein, we report a modular Sn-Ni bimetallic system in which we systematically vary the ancillary ligand on Ni, which, in turn, tunes the Sn center. This tuning is probed using Sn L1 XAS as a measure of electron density at the Sn center. We demonstrate that increased electron density at Sn centers accelerates the rate of σ-bond metathesis, and we employ this understanding to develop a highly active Sn-based catalyst for the hydroboration of CO2 using pinacolborane. Additionally, we demonstrate that engineering London dispersion interactions within the secondary coordination sphere of Sn allows for further rate acceleration. These results show that the electronics of main-group catalysts can be controlled without the competing effects of geometry perturbations and that this manifests in substantial reactivity differences.

Quasi-thermal Noise Spectroscopy Analysis of Parker Solar Probe Data: Improved Electron Density Model for Solar Wind

We present a comprehensive analysis of electron density measurements in the solar wind using quasi-thermal noise (QTN) spectroscopy applied to data from the first 15 encounters of the Parker Solar Probe mission (2018 November–2023 March). Our methodology involves the identification of the plasma line frequency and the calculation of plasma density based on in situ measurements. By analyzing over 2.1 million data points, we derive a power-law model for electron density as a function of radial distance from the Sun in the range of 13 to 50 R ☉: n e(r) = (343,466 ± 19921) × r (−1.87±0.11). This model provides improved estimates for localizing interplanetary solar radio bursts. Moreover, obtained electron densities can be used for calibrating particle instruments on board the Parker Solar Probe. We discuss its limitations and potential for further refinement with additional Parker Solar Probe encounters.

Deep learning assisted microwave-plasma interaction based technique for plasma density estimation

The electron density is a key parameter to characterize any plasma. Most of the plasma applications and research in the area of low-temperature plasmas (LTPs) are based on the accurate estimations of plasma density and plasma temperature. The conventional methods for electron density measurements offer axial and radial profiles for any given linear LTP device. These methods have major disadvantages of operational range (not very wide), cumbersome instrumentation, and complicated data analysis procedures. The article proposes a deep learning (DL) assisted microwave-plasma interaction-based non-invasive strategy, which can be used as a new alternative approach to address some of the challenges associated with existing plasma density measurement techniques. The electric field pattern due to microwave scattering from plasma is utilized to estimate the density profile. The proof of concept is tested for a simulated training data set comprising a low-temperature, unmagnetized, collisional plasma. Different types of symmetric (Gaussian-shaped) and asymmetrical density profiles, in the range 1016–1019 m−3, addressing a range of experimental configurations have been considered in our study. Real-life experimental issues such as the presence of noise and the amount of measured data (dense vs sparse) have been taken into consideration while preparing the synthetic training data-sets. The DL-based technique has the capability to determine the electron density profile within the plasma. The performance of the proposed DL-based approach has been evaluated using three metrics- structural similarity index, root mean square logarithmic error, and mean absolute percentage error. The obtained results show promising performance in estimating the 2D radial profile of the density for the given linear plasma device and affirms the potential of the proposed machine learning-based approach in plasma diagnostics.

New O Partial Photoionization Cross Sections Resolve Ionospheric EUV Remote Sensing Issues

AbstractThe ionospheric O+ number density can be measured remotely during the day by observing its optically thick 83.4 nm radiance. Some ambiguity is present in the process of retrieving the density due to uncertainties in the initial excitation rate. This can be removed by observing a companion optically thin emission at 61.7 nm originating from the O+(3s 2P) state, providing that the ratio of the initial excitation rates is known. Analyses of ICON EUV data using an 83.4/61.7 emission ratio of order 10 result in O+ densities lower by ∼2 than other measurements. Key to relating the two emissions is accurate knowledge of the partial photoionization cross sections and the spectroscopy of O+—the topic of this paper. Up to now, no independent evaluation of the ratio of the 83.4/61.6 emission ratio exists. The recent availability of state‐of‐the‐art calculations of O partial photoionization cross sections into a variety of O+ states presents an opportunity to evaluate the O+(2p4 4P)/O+(3s 2P) ionization rate ratio. We calculate excitation of these parent states of the emissions including both direct and cascade excitation from higher lying O+ energy states. The resulting theoretical prediction gives ratios that range from 13.5 to 12 from solar minimum to maximum, larger than the value of 10 used by the ICON 83.4 and 61.7 nm algorithm. The higher theoretical values for the ratio reconcile the ∼2 discrepancy between simultaneous ICON and other electron density measurements.