Helium Content Research Articles

The relationship between He and Cl− as a criterion for the formation of groundwater composition

The analysis of the relationship between 1611 parallel determinations of helium and chloride concentrations in the groundwater of crystalline shields and sedimentary basins was performed. The comparison showed that groundwaters have helium and chlorides concentrations in the range of 1.8 × 10−8 to 6.8 mol/m3 and of 5.6 × 10−3 to 6488 mol/m3, respectively, and relatively stable He/rCl ratios equal to 5.5 × 10−5 in sedimentary basins and 7.5 × 10−4 in crystalline shields. Such behavior of helium and chlorides shows that the formation of the groundwater composition is determined primarily by the processes of mixing fresh meteoric and saline sea waters with ancient brines from great depths. During sedimentation, sea water penetrates the subsurface and mixes with ancient brines. On land, fresh meteoric waters dilute the mixtures of seawater and ancient brines. Most of the radiogenic 4He and chlorides comes from the subsurface ancient brine. The radiogenic 4He in the host rocks plays a secondary role. Therefore, the concentration of 4He in saline groundwater reflects the size of the impurities of the ancient brine with a very high content of 4He, rather than the residence time within the subsurface.

Paleotemperature reconstruction using environmental isotopes and noble gases in groundwater in Morocco

A Turonian limestone-dolomite aquifer from the Tadla basin of Morocco was analysed using a multi-tracer approach (δ18O, δ2H, δ13C, 3H, 14C and noble gases) to reconstruct the paleotemperature evolution from the late Pleistocene to the Holocene. The Turonian aquifer was found to be suitable for a groundwater-based paleoclimate reconstruction, representing the Holocene–late Pleistocene epochs. After correction for young water contribution, mean residence times (MRTs) of groundwater were calculated using the Pearson radiocarbon model. Additionally, terrigenic helium content was used as an age indicator. Noble gas temperature (NGT) results from wells with groundwater ages corresponding to glacial periods showed an average of 17.2 ± 1.7°C. In contrast, samples of recent recharge water gave a mean NGT of 25.2 ± 1.3°C. This reveals a temperature difference of 8.0 ± 2.1 °C between the Holocene and late Pleistocene. This significant Pleistocene–Holocene temperature difference observed in Africa has considerable significance and can be extended to address an important topic relating to the nature of the wet epochs during which the fossil aquifers of North Africa were recharged. It is evident that this aquifer was recharged during both interglacial (warm) and glacial (cool) wet periods.

Granite is an Effective Helium Source Rock: Insights from the Helium Generation and Release Characteristics in Granites from the North Qinling Orogen, China

AbstractGlobal helium (He) shortage is a challenging problem; however, the types of helium source rock and the mechanisms of He generation and release therein remain still poorly understood. In this study, in order to evaluate the potential of granite as an effective helium source rock, we collected granitic samples from the North Qinling Orogen, Central China, in the south of the helium‐rich Weihe Basin. The helium generation and release behaviors in granite were studied through analysis of U and Th concentrations, EMPA images, and He and Ar concentrations and isotopic ratios extracted by crushing and stepwise heating. The results indicate that Ar has a better retention and a lower mobility than He. 3He/4He ratios released by crushing and stepwise heating are 0.016–0.056 RA and 0.003–0.572 RA, respectively, where RA is the atmospheric 3He/4He of 1.4×10‐6, reflecting a crustal and radiogenic source. Helium concentrations extracted by the two ways are 0.13–0.95 ucm3 STP/g and 7.82–115.62 ucm3 STP/g, respectively, suggesting that matrix‐sited He accounts for more than 98% of total helium preserved in granite. In addition, the total generated He amounts in granites are calculated based on the measured U and Th concentrations in granitic samples. Dividing the preserved He quantities by the generated He amounts, it turned out that less than 10% of He produced since the formation of the granite is preserved in the rock over geological time, suggesting that more than 90% generated He can be transferred to the Weihe Basin. Temperature and fracture are the two critical factors controlling He release. Based on the relationship between He diffusivity of granites and temperature and the He closure temperatures of a variety of U‐ and Th‐rich minerals (27–250°C), we estimate that He can be partially released out of granite at the depths <400 m and totally released at the depths >7800 m. Fractures provide effective transfer of free He from deep source rocks to shallow reservoirs. Finally, a model on granite as an effective helium source rock is established. We suggest exploring He resources in hydrocarbon basins with granitic basement (or adjacent to granite bodies), high geothermal field, and young active fractures.

Krypton-81 dating of the deep Continental Intercalaire aquifer with implications for chlorine-36 dating

Deep groundwater samples from the Continental Intercalaire (CI) aquifer in the Northern Tunisian Sahara have been analyzed for noble gases 3He, 4He, Ne and 81Kr, and for 14C to better constrain the groundwater residence time of this large transboundary aquifer. Its significant radiogenic 4He content and background-level 14C both indicate water older than a few tens of thousands of years. Distinct helium concentrations and Ne/He ratios suggest different groundwater flow paths through the Tozeur and Kebili regions. 81Kr is applied for the first time on the CI aquifer, providing more direct evidence for the presence of old groundwater with 81Kr/Kr ratios at 63% – 15% of the atmospheric value, corresponding to residence times of 150 – 630 ka. These newly obtained 81Kr ages enable a re-evaluation of the previously reported data from the Tozeur region in order to better constrain the input values of 36Cl/Cl and Cl. The initial 36Cl/Cl ratio is found to be 4 – 6 times larger than previously assumed, and the initial Cl concentration 6 – 15 times smaller. The results of 81Kr dating and the recalibrated 36Cl dating define an eastward age progression across >500 km of flow path from the Algerian to Tunisian sections. This study exemplifies the utility of 81Kr not only as an independent and conservative chronometer, but also as a supplemental measurement to better calibrate the parameters required for other age tracers, including cosmogenic 36Cl and radiogenic 4He.

Consistent Patterns of Change in Energetic and Fabrication Characteristics of Arcing in Inert Gas Mixtures

The influence of the shielding gas composition and the non-consumable electrode construction on the total and effective efficiency of welding was studied. It was found that value total efficiency is at minimum at 25 % helium content and is increasing with the He concentration growth in the gas mixture. The alteration of arc force impact on the welded metal depending on the current rate, shielding gas composition and cathode processing history was demonstrated. It was found that the arcs with a focused cathode spot feature higher value of the integral forced impact on the welded metal, comparing to the arcs with a diffuse cathode spot, regardless the shielding gas composition.

Impact of material migration and radiation damage on the reflectivity of molybdenum mirrors: laboratory test for DEMO

Molybdenum mirrors were irradiated with high-Z (Mo) and low-Z (He) ions to simulate the effect of plasma exposure on diagnostic mirrors to be applied in D-T fusion devices. Selected mirrors before irradiation were additionally coated with tungsten thin films of various thicknesses to simulate the real conditions in the reactor: tungsten erosion and migration. Irradiations were followed by reflectivity measurements and detailed microscopy observations. The threshold dose for the degradation of optical performance by 4He+ irradiation is below 0.1 × 1017 cm−2. The presence of tungsten films (4 and 10 nm in thickness) decreases total reflectivity by 30%–40% in the short wavelength and 5% (4 nm-thick film) and 12% (10 nm-thick film) in the infrared. Ion irradiation further worsens reflectivity by 5%–10%. The size of blisters visible on the surface of mirrors after irradiation depends on the thickness of tungsten films. Helium content after irradiation with helium ions of a dose 6 × 1017 cm−2 decreased during two years by 70% from the value measured directly after the implantation.

Signature of helium rain and dilute cores in Jupiter's interior from empirical equations of state

Measurements of Jupiter's gravity field by Juno have been acquired with unprecedented precision, but uncertainties in the planet’s hydrogen–helium equation of state (EOS) and the hydrogen–helium phase separation have meant that differences remain in the interior model predictions. We deduce an empirical EOS from Juno gravity field observations in terms of the hydrostatic equation and then investigate the structure and composition of Jupiter by comparison of the empirical EOS with Jupiter's adiabats obtained from the physical EOS. The deduced helium mass fraction suggests depletion of helium in the outermost atmosphere and helium concentration in the inner molecular hydrogen region, which is a signature of helium rain in Jupiter's interior. The deduced envelope metallicity (the heavy-element mass fraction) is as high in the innermost envelope as 11–13 times the solar value. Such a high metallicity provides sharp support to the dilute core model with the heavy elements dissolved in hydrogen and expanded outward. No matter how the core mass is varied, the empirical EOS derived from the two-layer interior model generally suggests higher densities in the innermost envelope than does the best-fit Jupiter's adiabat; this result is, again, a signature of dilute cores in Jupiter's interior. Moreover, no matter the core mass, the empirical EOS is found to exhibit an inflexion point in the deep interior, around 10 Mbar, which can be explained as the combined effect of helium concentration in the upper part and dilute cores in the lower part.

メタン・ヘリウム混合ガスハイドレートの生成−ヘリウム低濃度領域の場合−

メタン・ヘリウム混合ガスハイドレートの生成−ヘリウム低濃度領域の場合−

Модификация метода реконструкции концентраций гелия в глубинных подземных водах

Модификация метода реконструкции концентраций гелия в глубинных подземных водах

Probabilistic Estimation of the Helium Resources in the Central and Southern Areas of the Lena–Tunguska Petroleum Province

Abstract —We propose and test a method for probabilistic estimation of the scale and structure (distribution of helium concentrations in free gas, accumulations of different sizes, localization zones, and stratigraphic complexes) of helium and helium-containing gas resources. Summarizing the available geological information about the structure of the sedimentary cover and data on the revealed accumulations of helium-containing gases, we have first made probabilistic estimation of the scale and structure of their resources as well as helium resources in the central and southern areas of the Lena–Tunguska province. The forecast results will serve as a reliable basis for geological and economic estimation of helium resources, for long-term planning of gas field development in East Siberia and the Republic of Sakha, and for helium industrialization in these regions.

FACTORS DETERMINING THE CHANGE OF HELIUM CONCENTRATION IN UNDERGROUND WATERS OF UZBEKISTAN AND THE ACCORDING TERRITORIES

The article presents the results of the analysis of long-term regime observations of change in the concentrations of groundwater of Uzbekistan and adjacent territories. Based on these observations, the main factors affecting the changes of the quantitative content of helium. The results of the evaluation of the characteristics of the changes and distribution of helium in groundwater. The change of helium concentration in groundwater significantly influence the deformation and hydro-geodynamic and tectonic conditions. Described and quantified four factors with different concentrations of helium. They allow to correctly assess the variation of helium associated with seismic events.

Helium concentrations and isotope compositions in 10 km deep groundwaters

Helium isotopes are useful for tracing terrestrial water movement and calculating residence times, which have important implications for radioactive waste disposal and carbon capture and storage projects. Helium concentrations are generally measured directly in water samples; however, this is not always possible. In this scenario, the He concentration equilibrium between pore waters and He accessible volumes (e.g., fluid inclusions, hereafter HAV) in minerals (e.g., quartz) can be utilized to determine He concentrations. In this study, the He partial pressure was measured in HAVs of quartz grains collected from cores of the Kola Super Deep Borehole (KSDB) using isothermal He extraction/saturation experiments. A large fraction of He was released from these samples during the first interval of isothermal heating, indicating a destruction of the unstable HAVs, likely due to decrepitation of fluid inclusions. We present a new approach to calculate He partial pressures using only the He fraction released from the stable HAVs. This approach gives a He partial pressure pHe of ≅ 1.5 atm at depths of ~ 10 km. When combined with solubility data, this value suggests a high He concentration in the deep pore waters nearby the KSDB, ≅ 1.3 × 10−6 mol (cc H2O)−1, indicating a long residence time of He atoms in a deep water – mineral system, close to the age of the regional metamorphism (≅1700 Ma). The 3He/4He in the deep KSDB quartz samples (and the pore waters) are ~ 3 × 10−8, typical of radiogenic He generated in 10 km deep Archean rocks of the KSDB. Importantly, external fluxes are not needed to explain He isotope abundances in rocks, minerals and pore waters at these depths.

Numerical investigation on He and Ar gas convective cooling for optical fiber glass drawing at short draw towers

The inert purge gas plays an important role in mass manufacturing of optical fibers, as it is usually the mixture gas of helium and argon. The natural and forced convective effects of purge gas are numerically investigated through the process simulation of glass fiber drawing in a short draw tower furnace by employing an iterative computational scheme of neck-down prediction formulation and computational fluid dynamics simulation of purge gas flow. The furnace geometric model and process conditions are based on realistic manufacturing process. It is found that neck-down shape and draw tension are quite insensitive to change of gas flow rate and helium contents level. In contrast, the recirculatory flow pattern around preform neck-down region is observed when helium contents are low, suggesting the difficulty in flushing of contamination particles out of furnace system. The increase of helium contents combined with increased flow rate in purge gas mixture could completely remove such undesirable flow patterns.

One-dimensional model of hydrogen distribution in confined space based on Froude number

Some hydrogen mitigation study programs have been conducted to figure out the hydrogen distribution characteristics and provide useful information for codes development and validation. However, there is a lack of models with direct relations between hydrogen distribution and a non-dimensional parameter which governs the hydrogen flow, such as Froude number. This deficiency will lead to lack of understandings of the dominated force regimes. Therefore, in this paper, one-dimensional model of hydrogen distribution is built, based on Froude number. With theoretical study and fitting method, a semi-empirical formula is given, which is verified by experimental data obtained from pure plume conditions and buoyant jet conditions. Finally, this newly-built model is employed in typical accidents analysis. Three typical Froude numbers which are based on PANDA and TOSQAN study, are selected to get much closer to the real accidents. According to the evolution of helium concentration and concentration distinction, it can be found that obvious stratification may take place in the middle part and lower part of the containment model, while it turns to be more uniform in the top, corresponding to these three Froude numbers of 3.8, 17 and 280. Moreover, the higher the buoyancy is (Fr = 3.8), the more uniform the helium distribution throughout the containment model will be. The medium momentum will lead to significant stratification, which needs to be paid much attention in reactor design and accident mitigation.

Influence of helium-decoration on the interaction between 1/2 dislocation loop and edge dislocation in BCC iron

For ferritic steels served as structural materials for future nuclear reactors, a large number of helium atoms are expected to be introduced through transmutation reaction. Current experimental results prove that these helium atoms tend to segregate at different crystal defects and deteriorate the mechanical properties of materials severely. In this work, the helium segregation on 1/2[11‾1] dislocation loops (DLs) in body-centered cubic iron and the concomitant hardening effects were investigated by a combination of Monte Carlo and molecular dynamics methods. The Monte Carlo results reveal that the helium atoms are inclined to segregate as helium bubbles at six energetic favorable sites which divide the DLs periphery uniformly, irrespective of the shapes of DLs. The Molecular dynamics simulations were then performed to study the interaction between a moving edge dislocation and the helium-decorated DLs. In order to investigate the helium-decoration effects systematically, influence factors including the DLs size, helium content, and the relative geometric position between edge dislocations and DLs were considered. It is shown that the decoration of helium bubbles suppresses the absorption of DLs by the moving edge dislocation through hindering the movement of dislocation segments during the interaction. Four types of residual products induced by the edge dislocation-DLs interaction are observed, while three of them, including a pure <100> DL and two kinds of bi-DLs, had never been reported before. It is also found that helium-segregation overall increases the critical shear stress for the edge dislocation bypassing DLs. These results may be helpful for a deeper atomic-scale comprehension of the helium-induced hardening and embrittlement in ferritic steels.

Effects of Embedded Helium on the Microstructure and Mechanical Properties of Erbium Films.

A series of helium (He) charged nanograin-sized erbium (Er) films were deposited by direct current (DC)-magnetron sputtering with different He/Ar mixture gases. The microstructure and mechanical properties of He-charged Er films were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and nanoindentation. The helium concentrations in Er films, determined by elastic recoil detection analysis (ERDA), ranged from 0 to 49.6%, with the increase in He:Ar flow ratio up to 18:1. The XRD results show that the grain sizes of Er films decreased with and increase in He content. The embedded He atoms induced the formation of spherical nanometer He bubbles, and the diameter of the He bubbles increased with the He content. The hardness and Young’s modulus increased and decreased with the decreasing grain sizes of polycrystalline Er–He films. The mechanisms of mechanical properties with respect to the grain size and He content were discussed based on the Hall–Petch formula and composite spheres model.

Effect of helium-argon shielding gas in laser-metal inert-gas hybrid welded-brazed Al/steel dissimilar joint

Laser-metal inert-gas welding hybrid welding was applied to dissimilar butt joining of 304 stainless steel and 6063 aluminum alloy using three different shielding gas: 100% argon, 25% helium + 75% argon, and 50% helium + 50% argon. The influence of helium–argon shielding gas on the weld appearance and interfacial intermetallics layer of Al/stainless steel welding-brazing joint was discussed. The addition of helium can shrink arc, suppress laser plasma, and increase the stability of the droplet transfer process. Helium could not change the composition of the interface layer, which consists of θ-Fe(Al, Si)3 layer and τ5-Al7.2Fe1.8Si layer in the top, middle, and bottom regions of the joints. However, the interfacial intermetallics layer becomes thinner and the morphology was more uniform as the helium content changed from 0% to 50%. By analyzing the tensile fracture, it was found that the thicker θ-Fe(Al, Si)3 easily caused the fracture at the interface layer when using 100% argon. The highest tensile strength and the best ductility can be obtained by using 50% helium + 50% argon compared with that of joints obtained with 100% argon and 25% helium + 75% argon. Compared with joints welded in the pure argon atmosphere, the strength and ductility of joints increased by 18.4% and 191%, respectively.

Development of Gas Porosity along the Ion Range in Vanadium Alloys during Sequential Helium and Hydrogen Ion Irradiation

The development of helium porosity in vanadium and its alloys with tungsten, zirconium, and tantalum during sequential ion irradiation by 40-keV He+ ions at 650°C to a fluence of 5 × 1020 m–2 and 20-keV H+ ions at 20°C to a fluence of 5 × 1020 m–2 is studied by transmission electron microscopy. The microstructure and the development of porosity in the alloys are investigated along the ion range. Unlike He+ ion irradiation, the alloying elements during sequential He+ and H+ ion irradiation increase the gas swelling of vanadium: tantalum causes the maximum swelling and zirconium minimum one. Gas bubbles in the tantalum-containing alloys are located at the depths that are significantly more than the calculated helium and hydrogen ion ranges. Deep penetration of introduced gas atoms is shown occur mainly along the grain boundaries that are perpendicular to the irradiated surface. The largest bubbles (gas-filled pores) during He+ ion irradiation are found to grow at the depth with a high radiation vacancy concentration rather than the maximum helium concentration. In sequential He+ and H+ ion irradiation, a zone with large pores forms more deeply, in the ion range zone, and large pores in the 100-nm-thick layer transforms into high-density small bubbles.

MATERIAL OF COMETARY NUCLEI AND ASTEROIDS CAN BE STUDIED IN THE EARTH’S ORBIT

The Solar system is formed from a pri- mary gas-dust cloud. Asteroids and cometary nuclei are made of the same substance. Therefore, the study of their debris will help determine their properties. It is best to investigate the substance of meteoroids in the laboratory. The presence of radioactive chemical elements in meteor- ites provides important information about their age. The study of the isotopic composition and content of uranium and thorium gives an age of a meteorite substance of 4.6 billion years. Measurement of cosmogenic isotopes in meteorites and analysis of their content allows us to de- termine the size, mass and age of meteoritic bodies before falling to Earth. By measuring the content of tritium and helium in a meteorite, the average intensity of the cosmic rays bombarding the sample is estimated. Every day, 100- 1000 tons of meteorite material falls on the Earth’s sur- face. A large mass falls to the surface under the action of meteor showers. Meteor showers are formed from the remnants of the nuclei of known comets and asteroid bod- ies. To study the substance of the nucleus of comet Chur- yumov-Gerasimenko, a spacecraft was sent to it worth about 1 billion euros. We offer, that to study the material of some nuclei of comets and asteroids, it is possible to take meteoroid samples directly in outer space in the Earth’s orbit. There, meteoroid particles must be captured, preserved and delivered to Earth for a thorough study. To capture matter from a specific parent cometary nucleus or asteroid in outer space, traps made of silicon dioxide, which are filled with airgel, can be used. The material of the traps allows you to capture particles flying at high speed without overheating them. This allows you to save organic and other molecules in such particles. Such traps should be activated at the moments of maximums of the selected meteor showers.

A helium stratified and ingassed lower mantle: resolving the helium paradoxes

It is generally believed a variation of 3He/4He isotopic ratios in the mantle is due to only the decay of U and Th, which produces 4He as well as heat. Here we show that not only 3He/4He isotopic ratios but also helium contents can be fractionated by thermal diffusion in the lower mantle. The driving force for that fractionation is the adiabatic or convective temperature gradient, which always produces elemental and isotopic fractionation along temperature gradient by thermal diffusion with higher light/heavy isotopic ratio in the hot end. Our theoretical model and calculations indicate that the lower mantle is helium stratified, caused by thermal diffusion due to ~ 400 °C temperature contrast across the lower mantle. The highest 3He/4He isotopic ratios and lowest He contents are in the lowermost mantle, which is a consequence of thermal-diffusion fractionation rather than the lower mantle is a primordial and undegassed reservoir. Therefore, oceanic-island basalts derived from the deepest lower mantle with high 3He/4He isotopic ratios and less He contents—the long-standing helium paradox, is solved by our model. Because vigorous convection in the upper mantle had resulted in disordered or disorganized thermal-diffusion effects in He, Mid-ocean ridge basalts unaffected by mantle plume have a relatively homogenous and lower 3He/4He isotopic compositions. Our model also predicts that 3He/4He isotopic ratios in the deepest lower mantle of early Earth could be even higher than that of Jupiter, the initial He isotopic ratio in our solar system, because the temperature contrast across the lower mantle in the early Earth is the largest and less 4He had been produced by the decay of U and Th. Moreover, the early helium-stratified lower mantle owned the lowest He contents due to over-degassing caused by the largest temperature contrast. Consequently, succeeding evolution of the lower mantle is a He ingassed process due to secular cooling of the deepest mantle. This explains why significant amount of He produced by the decay of U and Th in the lower mantle were not released, another long-standing heat–helium paradox.