Analysis Electron Research Articles

Holistic numerical calibration of the iMESA electrostatic analyzer.

A drifted Maxwellian velocity distribution is the most common model used to interpret the data from low-energy charged-particle instruments onboard spacecraft that are used to investigate the ambient plasma environment in the low Earth orbit (LEO). An original method is presented for determining the flow parameters (density, temperature, and flow energy) of such a distribution from the output of the integrated miniaturized electrostatic analyzer, which has been successfully flown on several LEO missions. Rather than attempting to deconvolve from the on-orbit data the analyzer's response to an ideal, monoenergetic input, numerical simulation is used to predict and parameterize the response of the device to an input distribution that includes an isotropic, non-zero temperature, yielding a straightforward method for extracting the flow parameters from the spacecraft data. The method is computationally simple enough to be incorporated into a robust algorithm suitable for rapid batch processing or real-time analysis of data.

АУТИГЕННОЕ МИНЕРАЛООБРАЗОВАНИЕ КАК ОБЪЕКТИВНЫЙ ФАКТОР ТРАНСФОРМАЦИИ ТЕХНОГЕННЫХ РОССЫПЕЙ

The paper presents the data of analytical scanning electron microscopy and mineralogical methods for studying the morphology and chemical composition of spiral man-induced products, metal spheroids and native gold from the alluvial mining waste. In all samples, including the tungsten “spiral”, mercurous gold was found. The spheroids were diagnosed as lead ones with a fine impregnation of alumina-silicate substance, antimony and copper ones with autigenic isometric and xenomorphic mineral deposits on the surface, etc. The inclusion of carbon in many newly formed minerals confirms the leading role of this element in the process of technogenic mineral formation as a reducing agent. The identified chemical diversity of numerous ore and rock phases is explained by complex physico-chemical processes occurring in the technogenic system, in which not only the residual gold is transformed, but also new ore-mineral complexes, including gold-containing ones, arise.

Compact scanning retarding potential analyzer

A miniature scanning electrostatic energy analyzer has been developed for measurements of the ion energy distribution in low-pressure plasma discharges. The retarding potential analyzer utilizes four grids to reject the incident electron flux and discriminate the ion energy. It features a compact size of 5-mm diameter and 2.5-mm thickness and uses a simple configuration to mount the grids and provide voltage isolation using high temperature ceramic cement that avoids complicated grid alignment or MEMS fabrication techniques. Mounting on a fast-scanning two-axis probe drive eliminates overheating of the ceramics and subsequent current leakage, which permits insertion into challenging locations and provides profiles of the ion energy in the plasma discharge. Guidelines for the analyzer design for high density operation are discussed, and the performance of the analyzer is shown for measurements in a hollow cathode plume in xenon plasmas.

The Effect of Complexing Reagents on Flotation of Sulfide Minerals and Cassiterite from Tin-Sulfide Tailings

ABSTRACT Using a combination of UV-spectrophotometry, IR-Furie spectroscopy, analytical scanning electron (LEO 1420VP INCA OXFORD ENERGY 350) and laser (KEYENCE VK-9700) microscopy the effect of complexing reagents DBDTC, TMPPh, TOFA, and IM-50 on adsorption layer on the surface of chalcopyrite, galena, arsenopyrite, and cassiterite was studied. The individual formation character of the adsorption layer on each of the listed minerals was identified and the sizes of thin discrete films of the newly formed reagent phase, the strength of their fixation, and the coverage area of the mineral surface were determined. Kinetic photometry established the effective flocculation of cassiterite slimes by a thermomorphic polymer with a phosphine group TMPPh, which helps to reduce the loss of tin with fine fractions. TOFA is a selective tin collector and has advantages over IM-50 in terms of the fixation contrast on cassiterite and quartz. Tests of the developed reagent modes using a composition of complexing reagents have shown the possibility of obtaining sulfide and tin concentrates that met the requirements of metallurgical processing.

Evaluating the Performance of a Plasma Analyzer for a Space Weather Monitor Mission Concept

AbstractWe use historical analysis of solar wind plasma and coronal mass ejections to define the range of performance required for an ion analyzer for future space weather monitoring missions. We adopt the design of a top hat electrostatic analyzer, capable of measuring the plasma protons and constructing their three‐dimensional distribution functions. The design is based on previous heritage instruments and allows monitoring of extreme space weather events. In order to evaluate the future observations and their analysis methods, we model the expected response of the instrument in simulated plasma conditions. We evaluate a novel analysis method which can determine on board the plasma bulk properties, such as density, velocity, and temperature from the statistical moments of the observed velocity distribution functions of the plasma particles. We quantify the accuracy of the derived parameters critical for space weather purposes, by comparing them with the corresponding input solar wind parameters. In order to validate the instrument design, we examine the accuracy over the entire range of the input parameters we expect to observe in solar wind, from benign to extreme space weather conditions. We also use realistic parameters of fast solar wind streams and interplanetary coronal mass ejections as measured by the Advanced Composition Explorer spacecraft, to investigate the performance of the example instrument and the accuracy of the analysis. We discuss the achieved accuracy and its relevance to space weather monitoring concepts. We address sources of significant errors, and we demonstrate potential improvements by using a fitting analysis method to derive the results.

The integrated miniaturized electrostatic analyzer: A space plasma environment sensor.

The integrated Miniaturized Electrostatic Analyzer (iMESA) was a satellite-based ionospheric sensor that operated on NASA's Space Test Program Satellite (STPSat-3) from December 2013 to July 2019. The instrument's scientific objective was to (1) measure the plasma density in low Earth orbit, (2) measure the plasma temperature in low Earth orbit, and (3) quantify the spacecraft potential with respect to the ambient plasma potential in the ionosphere. iMESA sampled the ionosphere every 10 s by measuring the ion current density through the ESA as a result of the motion of the spacecraft through the plasma. Current density spectra were transmitted to the ground where they were post-processed into ion density spectra and then analyzed numerically to determine the ion density, ion temperature, and spacecraft potential. This article discusses the instrument design and simulation, the determination of a geometric factor, and data processing procedures and evaluates the final data product with regard to the mission success criteria. The ion density and ion temperature captured by the iMESA instrument are on the same order and range as the values predicted in the literature. The spacecraft potential was also quantified. The conclusion after the evaluation of the instrument's data product is that the scientific mission is successful on all three points.

Design and Optimization of a High-Time-Resolution Magnetic Plasma Analyzer (MPA)

In-situ measurements of space plasma throughout the solar system require high time resolution to understand the plasma’s kinetic fine structure and evolution. In this context, research is conducted to design instruments with the capability to acquire the plasma velocity distribution and its moments with high cadence. We study a new instrument design, using a constant magnetic field generated by two permanent magnets, to analyze solar wind protons and α-particles with high time resolution. We determine the optimal configuration of the instrument in terms of aperture size, sensor position, pixel size and magnetic field strength. We conduct this analysis based on analytical calculations and SIMION simulations of the particle trajectories in our instrument. We evaluate the velocity resolution of the instrument as well as Poisson errors associated with finite counting statistics. Our instrument is able to resolve Maxwellian and κ-distributions for both protons and α-particles. This method retrieves measurements of the moments (density, bulk speed and temperature) with a relative error below 1%. Our instrument design achieves these results with an acquisition time of only 5 ms, significantly faster than state-of-the-art electrostatic analyzers. Although the instrument only acquires one-dimensional cuts of the distribution function in velocity space, the simplicity and reliability of the presented instrument concept are two key advantages of our new design.

Electrostatic energy analyzer for nanotechnology applications

Electrostatic energy analyzers are key instruments in the wide field of the Electron Spectroscopy, and the Auger Electron Spectroscopy is one of commonly used technique within this area. The paper presents a new energy analyzer based on combination of a face-field and CMA configurations and some experimental Auger spectra obtained from nanostructures synthesized. The data obtained show that the presented analyzer's energy resolution and design parameters are superior to the data of the well known standard CMA.

Structure and Mineralogy of Hydrophilic and Biwettable Sub-2 µm Clay Aggregates in Oil Sands Bitumen Froth

A primary concern of commercial mined oil sands operations is the extent to which one can minimize the content of water and solids contaminants in the solvent-diluted bitumen products resulting from the bitumen production processes. During bitumen production, particles of about 2 µm or less may be responsible for the stabilization of water-in-bitumen emulsions that form during aqueous extraction of bitumen and purification of bitumen froth subsequently during the froth treatment processes, thus leading to the presence of those contaminants in solvent-diluted bitumen products. In this study, we separate and analyze sub-2 µm clay solids isolated from typical bitumen froth fed to a froth treatment plant at a commercial mined oil sands operation. Analytical transmission electron microscopy (TEM) with spatially-resolved energy-dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) demonstrate key differences in morphology and composition between sub-2 µm clay aggregates with two distinct wettability characteristics: hydrophilic vs. biwettable particle surfaces. In particular, clay platelets with <200 nm lateral dimensions and thicknesses of a few atomic layers, which are intermixed within coarser sub-2 µm clay aggregates, are found to confer clear differences in morphological characteristics and wettability behaviors to the sub-2 µm clay aggregates. The <200 nm clay platelets found within sub-2 µm biwettable clays tend to arrange themselves with random orientations, whereas <200 nm clay platelets within sub-2 µm hydrophilic clays typically form well-ordered face-to-face stacks. Moreover, in biwettable sub-2 µm clay aggregates, <200 nm clay platelets often cover the surfaces of ~1–2 µm sized mineral particles, whereas similarly sized mineral particles in hydrophilic sub-2 µm clay aggregates, in contrast, generally have exposed surfaces without clay platelet coverage. These biwettable vs. hydrophilic behaviors are attributed to a difference in the surface characteristics of the <200 nm clay platelets caused by toluene-unextractable organic carbon coatings. Nanometer-scale carbon mapping reveals an inhomogeneous toluene-unextractable organic carbon coating on the surfaces of <200 nm platelets in biwettable clays. In contrast, hydrophilic clays have a significantly lower amount of toluene-unextractable organic carbon, which tends to be concentrated at steps or near metal oxide nanoparticles on clay particle surfaces. Mixing surface-active organic species, such as asphaltene, resin, or carboxylic organic acids of various types with inorganic solids can lead to a dramatically enhanced emulsion stability. Consequently, understanding the origin and characteristics of sub-2 µm clay solids in bitumen froth is important to (i) clarify their potential role in the formation of stable water-in-oil emulsions during bitumen production and (ii) improve froth treatment process performance to further reduce contaminant solids in solvent-diluted bitumen products. We discuss the implications of our results from these two perspectives.

Electrical characterization of carbon plasma generated by excimer laser ablation of graphite

The vacuum expansion of a transient carbon plasma produced by KrF excimer laser at moderate fluences is investigated by separating different types of ions with an electrostatic energy analyzer. In the retarding field of the analyzer, the ion current reveals a multi-peak structure and the signal deconvolution allows obtaining information on the ion abundance and thermal velocity. A significant increase of C2+ and C1+ fast ions production with the laser pulse energy is observed, while the amount of slower singly charged ions in the thermal plasma part is less affected by the irradiation conditions. By time-integration of the recorded current, the total collected charge vs. retarding potential characteristic is built and a derivative method allows obtaining the energy distribution function on the plasma plume axis, in good agreement with the shifted Maxwell-Boltzmann distribution. Future developments of this method are possible through comparison with theoretical fractional ion populations.

Development, installation, and offline-beam testing of a chopping and deflecting system for the High Current Injector at IUAC

A chopping and deflecting system (CDS) has been designed, fabricated, and tested to provide the chopped beam with various frequencies, to the experimental facilities of the Inter-University Accelerator Centre (IUAC), New Delhi. The CDS comprises four pairs of deflecting electrodes with an ascending gap from 15 mm to 21 mm to achieve the utmost effective electric field and the highest current within the same input voltage. The design, physical structure, and slit location of CDS have been verified with various simulation codes. The 90-degree beamline of a low energy ion beam facility was extended to install and test the CDS assembly to validate its electric design. The beamline was aligned using theodolite and dimensions measurement was carried out using a coordinate measuring machine (CMM). A floating type-high voltage power supply has been developed indigenously to apply the DC voltage across the four pairs of deflecting electrodes, and the amount of deflection was measured accordingly at slit location. A beam profile digitizer was used to measure the precise beam deflection within the error of ~ 0.25 mm. The measured beam deflection matches very well with the simulated value. The measured data shows that the amount of beam deflection is independent of the charge state, energy, and mass of the charged particle beam. The various ion beams of different energy, charge state, and mass were injected into the CDS system to verify the accuracy, precision, and repeatability of the measurements. The ion beam test results extend the capability of CDS to use as an electrostatic charge state analyzer. The beam test results reveal that deflection voltage directly depends on the ratio of energy to charge state (E/q). The development, installation, and offline-beam test are discussed in the article.

Coronagraphic observations of the lunar sodium exosphere 2018–2019

Remote observations of the lunar sodium corona have been obtained with the Goddard Lunar Coronagraph located at the Winer Observatory in Sonoita, Arizona. We previously reported the results of observations in the spring, 2017, observing season (Killen et al., 2019). We report herein the results of the 2018–2019 observing campaign. We show definitive effects on the corona - the extended lunar sodium exosphere above 150 km from the surface - of enhanced ion flux onto the Moon as measured by the ARTEMIS ElectroStatic Analyzer. The three observations in this dataset with the largest column abundances are associated with entrance of the Moon into the magnetosheath. The enhancement in the exosphere due to ion flux is not long-lived after the enhanced ion influx decreases, confirming the findings of Killen et al., 2012. The column abundance is greatest at both the dawn and dusk terminators as predicted and simulated by Smyth and Marconi, 1995. The cause of the increased scale height at the terminators is consistent with radiation pressure acceleration anti-sunward. We report a shallow decline of column abundance with increasing latitude which is also consistent with radiation pressure acceleration. Most of our measured scale heights are on the order of 800–1800 km, increasing at high latitudes, consistent with the data set published in Killen et al., 2019. Although the intensity extrapolated to the surface decreases with latitude, the scale height increases with latitude, so that the exospheric column decreases more slowly with increasing latitude than does a cosine function.

The Solar Orbiter Solar Wind Analyser (SWA) suite

The Solar Orbiter mission seeks to make connections between the physical processes occurring at the Sun or in the solar corona and the nature of the solar wind created by those processes which is subsequently observed at the spacecraft. The mission also targets physical processes occurring in the solar wind itself during its journey from its source to the spacecraft. To meet the specific mission science goals, Solar Orbiter will be equipped with both remote-sensing and in-situ instruments which will make unprecedented measurements of the solar atmosphere and the inner heliosphere. A crucial set of measurements will be provided by the Solar Wind Analyser (SWA) suite of instruments. This suite consists of an Electron Analyser System (SWA-EAS), a Proton and Alpha particle Sensor (SWA-PAS), and a Heavy Ion Sensor (SWA-HIS) which are jointly served by a central control and data processing unit (SWA-DPU). Together these sensors will measure and categorise the vast majority of thermal and suprathermal ions and electrons in the solar wind and determine the abundances and charge states of the heavy ion populations. The three sensors in the SWA suite are each based on the top hat electrostatic analyser concept, which has been deployed on numerous space plasma missions. The SWA-EAS uses two such heads, each of which have 360° azimuth acceptance angles and ±45° aperture deflection plates. Together these two sensors, which are mounted on the end of the boom, will cover a full sky field-of-view (FoV) (except for blockages by the spacecraft and its appendages) and measure the full 3D velocity distribution function (VDF) of solar wind electrons in the energy range of a few eV to ∼5 keV. The SWA-PAS instrument also uses an electrostatic analyser with a more confined FoV (−24° to +42° × ±22.5° around the expected solar wind arrival direction), which nevertheless is capable of measuring the full 3D VDF of the protons and alpha particles arriving at the instrument in the energy range from 200 eV/q to 20 keV/e. Finally, SWA-HIS measures the composition and 3D VDFs of heavy ions in the bulk solar wind as well as those of the major constituents in the suprathermal energy range and those of pick-up ions. The sensor resolves the full 3D VDFs of the prominent heavy ions at a resolution of 5 min in normal mode and 30 s in burst mode. Additionally, SWA-HIS measures 3D VDFs of alpha particles at a 4 s resolution in burst mode. Measurements are over a FoV of −33° to +66° × ±20° around the expected solar wind arrival direction and at energies up to 80 keV/e. The mass resolution (m/Δm) is > 5. This paper describes how the three SWA scientific sensors, as delivered to the spacecraft, meet or exceed the performance requirements originally set out to achieve the mission’s science goals. We describe the motivation and specific requirements for each of the three sensors within the SWA suite, their expected science results, their main characteristics, and their operation through the central SWA-DPU. We describe the combined data products that we expect to return from the suite and provide to the Solar Orbiter Archive for use in scientific analyses by members of the wider solar and heliospheric communities. These unique data products will help reveal the nature of the solar wind as a function of both heliocentric distance and solar latitude. Indeed, SWA-HIS measurements of solar wind composition will be the first such measurements made in the inner heliosphere. The SWA data are crucial to efforts to link the in situ measurements of the solar wind made at the spacecraft with remote observations of candidate source regions. This is a novel aspect of the mission which will lead to significant advances in our understanding of the mechanisms accelerating and heating the solar wind, driving eruptions and other transient phenomena on the Sun, and controlling the injection, acceleration, and transport of the energetic particles in the heliosphere.

Plasma potential and fluctuations measurements by HIBD with 90° cylindrical energy analyzer on the ISTTOK tokamak

The Heavy Ion Beam Diagnostic (HIBD) is known as unique tool for direct measurements of plasma potential in fusion devices such as tokamaks and stellarators. On small ISTTOK tokamak (R = 0.45 m, a = 0.085 m, B = 0.5 T, Ip = 4 kA, <ne> = 4 × 1018 m−3) the HIBD is operated with primary Xe+ ion beam with E = 22−24 keV of energy and a Multiple Cell Array Detector (MCAD) to measure the product of plasma neσ and its fluctuations simultaneously at a number of sample volumes along primary beam trajectory across the plasma. To upgrade the ISTTOK HIBD capabilities to measure the plasma potential and its fluctuations a multichannel 90° cylindrical electrostatic energy analyzer (CEA) operated in a beam deceleration mode has been proposed.This paper presents the first results of the plasma potential and its fluctuations measurements by the one-channel CEA prototype operated in two-times deceleration mode and in real conditions of the HIBD experiments on ISTTOK. Using an indirect CEA calibration approaches, the value of the potential Φ ∼ −350 V has been measured in the plasma core. Also, the plasma potential fluctuations Φ∼ ∼ 40 V have been observed. The obtained results demonstrate and confirm the applicability of the 90° cylindrical electrostatic energy analyzer and its operation in deceleration mode for the plasma potential and its fluctuations measurements by HIBD.

Mechanism of Structural Changes in the Surface State and Physicochemical Properties of Columbite and Eudialyte upon Exposure to Low-Temperature Plasma

The mechanism of change in the structurally sensitive surface characteristics and physicochemical properties of rare-metal minerals (columbite and eudialyte) as a result of exposure to low-temperature atmospheric-pressure plasma is studied by means of DRIFT, analytical electron (SEM) and atomic force (AFM) microscopy, and measuring microhardness, electrokinetic potential, and angles of wetting. Results demonstrate the fundamental possibility of using low-temperature plasma to improve the efficiency of softening and altering the structural and chemical properties, surface hydrophobicity, and sorption activity of rare-metal minerals.

Changes in the Surface Morphology, Microhardness, and Physicochemical Properties of Natural Minerals under the Influence of a Dielectric Barrier Discharge

Analytical electron (SEM-EDX) and confocal laser scanning microscopy (CLSM), microhardness testing, determining the contact angle of wetting, and other means are used to study the mechanism behind changes in the structural state of surfaces, and the mechanical, physicochemical, and technological properties of semiconductor ore minerals (sulfides) and natural quartz under conditions of a pulsed dielectric barrier discharge at atmospheric pressure in air. Due to the action of the products of low-temperature plasma and other effective factors resulting from a discharge, the minerals soften (general maximum relative reduction in microhardness ~7–30%), and the morphology, roughness, contact angle of wetting of the surfaces of mineral polished sections, and the flotation activity of sulfide minerals change with respect to the duration of plasma treatment.

Charge-separated spectra of suprathermal highly charged bismuth ions in a dual laser-produced plasma soft x-ray source.

We investigated the charge-separated spectra of highly charged suprathermal bismuth (Bi) ions from a dual laser-produced plasma soft x-ray source developed for soft x-ray microscopy. The charge distribution of these suprathermal ions emitted from a solid planar Bi target was measured by an electrostatic energy analyzer. The maximum ionic charge state was observed to be Z = 17 and to possess a maximum energy of about 200 keV. This evaluation provides important information essential for the development of debris mitigation schemes in a soft x-ray microscope.

Short-Term Introduction of Fullerene C60 Nanoparticles in Rat Small Intestine Induces the Rapid Development of Hepatocyte Pathology

Fullerenes C60 are used in various fields of industry; therefore, issues of studying their biosafety for living organisms, their biodistribution in organs and tissues organs and tissues of laboratory animals, and their induction of cellular pathologies are very important. In recent years, analytical and transmission electron microscopy (TEM) have proven their efficiency in detecting carbon nanoparticles in biological samples. Combining these methods can reveal pathological changes in cells induced by nanoparticles and detect accumulations of nanoparticles in them. The aim of the study was to reveal cellular pathologies upon direct short-term administration of fullerene C60 nanoparticles into the gastrointestinal tract (GIT) of rats and to detect nanoparticles in samples of the small intestine and liver. The histological and ultrastructural analysis did not reveal pathological changes in the small intestine, but degenerative changes in hepatocytes were indicated in the form of accumulation of lipid inclusions. High-performance liquid chromatography and analytical TEM revealed no accumulations of fullerene C60 nanoparticles in the studied samples. Probably, hepatosteatosis may be a consequence of the indirect influence of C60 nanoparticles on liver cells. Apparently, the surface of fullerene C60 undergoes modifications in the GIT, and its contact with the cells of the small intestine induces the synthesis of proinflammatory cytokines, with their subsequent entry into the liver, leading to the rapid development of fatty degeneration. Revealing and identifying modified C60 nanoparticles and their metabolites, in turn, is a complex problem, which in the future can be solved using radiotracers, mass spectrometry, and modern metabolomic technologies.

Quantitation of Iron(III) Ions Complexed by Tetraphenylporphyrin and Its Effect on the Structure of Ultrafine Poly(3-Hydroxybutyrate) Fibers

We demonstrate a methodical approach to quantitation of iron ions on the surface and in bulk of ultrafine fibrous materials of poly(3-hydroxybutyrate) (P3HB), taking the tetraphenylporphyrin iron(III) chloride (FeClTPP) complex as an example. Ultrafine fibers based on the P3HB biopolymer and containing 1–5 wt % of FeClTPP are fabricated by electrospinning. As analytical techniques, UV spectroscopy and electron paramagnetic resonance (EPR) are successfully used for quantitation of iron(III) species. We identify the effect of the complex on the crystalline phase and segmental mobility of P3HB molecules in amorphous domains of the ultrafine fibers. Adding small amounts of FeClTPP (up to 5%) leads to a marked increase in the crystallite size and the degree of P3HB crystallinity and to densification of the amorphous regions. Our findings suggest that UV spectroscopy and EPR are promising analytical techniques for quantitation of iron ions in nonwoven fibrous sorbents designed for removal of oil products and heavy metals from waste waters.

The Acceleration of Lunar Ions by Magnetic Forces in the Terrestrial Magnetotail Lobes

AbstractIn order to study the acceleration of ions originating from the tenuous exosphere and surface of the Moon, we analyzed data from the ElectroStatic Analyzer (ESA) and Flux Gate Magnetometer (FGM) carried by the Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) spacecraft. Previous investigations have modeled the acceleration of lunar ions by the motional electric field of the surrounding plasma. However, in the terrestrial magnetotail, where the lunar ion density can equal or even exceed the ambient plasma density, other forces may play an important role in the tenuous plasma environment. Determining what forces govern lunar ion motion is important in understanding their interaction with the ambient plasma in the unique environment of the magnetotail. Based on a detailed analysis of two individual ARTEMIS observations, we find that magnetic pressure and magnetic tension forces may play an important role in accelerating the lunar ions.