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Noble gases are ideal natural tracers to characterize the storage, migration and origin of fluids in geological environments. They are chemically and biologically inert and therefore are only partially separated by physical processes including the one related to the molecular diffusion phenomenon, so called kinetic fractionation. However, its precise quantification is difficult to achieve and its modeling is still open for debates. Thus, in this work, we have investigated the capability of simple and predictive models to estimate elemental and isotopic fractionation of noble gases in various geological fluids. To do so, molecular dynamics simulations on noble gases in water, gas and oil under sub-surface conditions were performed. These numerical results were found to be consistent with previous ones including experiments and molecular simulations when available, i.e. in water. Interestingly, it appeared that the widely used square-root law is able to provide a good prediction for elemental fractionation between noble gases in all solvents, except for helium. Such unexpected result from the theoretical point of view is explained by a peculiar relationship between the molecular mass and the molecular size of noble gas elements. Regarding the noble gas isotopic fractionation, the square-root law is shown to be unable to provide reasonable results, confirming recent experimental and numerical works. As expected, it has been noticed that the kinetic theory relation provides a reasonable estimate of the isotopic fractionation in gas whereas it deteriorates in water and in oil. Finally, using the previous findings, we propose a simple and predictive scheme for the isotopic fractionation of noble gases in all studied geo-fluids which is noticeably better than both the square-root and the kinetic theory relations.

Hydrogen eliminates carbon emissions from compression ignition (CI) engines, while noble gases eliminate nitrogen oxide (NO x ) emissions by replacing nitrogen. Noble gases can increase the in-cylinder temperature during the compression stroke due to their high specific heat ratio. This paper aims to find the optimum parameters for hydrogen combustion in an argon–oxygen atmosphere and to study hydrogen combustion in all noble gases, providing hydrogen combustion data with suitable engine parameters to predict hydrogen ignitability under different conditions. Simulations are performed with Converge CFD software based on the Yanmar NF19SK direct injection CI (DICI) engine parameters. The results are validated with the experimental results of hydrogen combustion in an argon–oxygen atmosphere with a rapid compression expansion machine (RCEM), and modifications of the hydrogen injection timing and initial temperature are proposed. Hydrogen ignition in an argon atmosphere is dependent on a minimum initial temperature of 340 K, but the combustion is slightly unstable. Helium and neon are found to be suitable for hydrogen combustion in low compression ratio (CR) engines. However, krypton and xenon require temperature modification and a high CR for stable ignition. Detailed parameter recommendations are needed to improve hydrogen ignitability in conventional diesel engines with the least engine modification.

Superelectrophilic monoanions [B12 (BO)11 ]- and [B12 (OBO)11 ]- , generated from stable dianions [B12 (BO)12 ]2- and [B12 (OBO)12 ]2- , show great potential for binding with noble gases (Ngs). The binding energies, quantum theory of atoms in molecules (QTAIM), natural population analysis (NPA), energy decomposition analysis (EDA), and electron localization function (ELF) were carried out to understand the B-Ng bond in [B12 (BO)11 Ng]- and [B12 (OBO)11 Ng]- . The calculated results reveal that heavier noble gases (Ar, Kr, and Xe) bind covalently with both [B12 (BO)11 ]- and [B12 (OBO)11 ]- with large binding energies, making them potentially feasible to be synthesized. Only [B12 (OBO)11 ]- could form a covalent bond with helium or neon but the small binding energy of [B12 (OBO)11 He]- may pose a challenge for its experimental detection.

129Xe NMR has been proven to be a powerful tool to investigate the structure of porous materials. Xenon is a monatomic noble gas which could be used as a probe due to the extremely sensitive to its local environment. Optical pumping techniques for production of hyperpolarized (HP) xenon have led to an increase of sensitivity up to orders of magnitude compared with traditional 129Xe NMR. This review summarizes the application of this technique in porous materials and heterogeneous catalysis in recent ten years, involving of zeolites, metal-organic frameworks (MOFs), catalytic process and kinetics.

We systematically explore the stability and properties of [B12X11NG]- adducts resulting from the binding of noble gas atoms to anionic [B12X11]- clusters in the gas phase of mass spectrometers. [B12X11]- can be obtained by stripping one X- off the icosahedral closo-dodecaborate dianion [B12X12]2-. We study the binding of the noble gas atoms He, Ne, Ar, Kr, and Xe to [B12X11]- with substituents X = F, Cl, Br, I, and CN. While He cannot be captured by these clusters and Ne only binds at low temperatures, the complexes with the heavier noble gas atoms Ar, Kr, and Xe show appreciable complexation energies and exceed 1 eV at room temperature in the case of [B12(CN)11Xe]-. The predicted B-NG equilibrium distance in the complexes with Ar, Kr, and Xe is only 0.10-0.25 A longer than the sum of the covalent radii of the two corresponding atoms, and a significant charge transfer from the noble gas atom to the icosahedral B12 cage is observed.

The coordination chemistry of KrF2 has been limited in contrast with that of XeF2 , which exhibits a far richer coordination chemistry with main-group and transition-metal cations. In the present work, reactions of [XeF5 ][AsF6 ] with KrF2 in anhydrous HF solvent afforded [F5 Xe(FKrF)AsF6 ] and [F5 Xe(FKrF)2 AsF6 ], the first mixed krypton/xenon compounds. X-ray crystal structures and Raman spectra show the KrF2 ligands and [AsF6 ]- anions are F-coordinated to the xenon atoms of the [XeF5 ]+ cations. Quantum-chemical calculations are consistent with essentially noncovalent ligand-xenon bonds that may be described in terms of σ-hole bonding. These complexes significantly extend the XeF2 -KrF2 analogy and the limited chemistry of krypton by introducing a new class of coordination compound in which KrF2 functions as a ligand that coordinates to xenon(VI). The HF solvates, [F5 Xe(FH)AsF6 ] and [F5 Xe(FH)SbF6 ], are also characterized in this study and they provide rare examples of HF coordinated to xenon(VI).

Doğal radyasyon kaynaklarının yaklaşık %50’sini oluşturan radon; renksiz kokusuz ve duyu organları ile algılanamayan radyoaktif ağır bir soy gazdır. Radon ve bozunum ürünleri; kayaçlarda ve topraktaki doğal uranyum elementinin radyoaktif bozunma serisi ürünü olan radyuma ve radyumun da bir dizi bozunumu sonucu oluşur. Radon suda ve organik çözücülerde oldukça kolay çözünebilmekte, bozunmadan önce uzun mesafeler kat edebilmekte ve yeraltı sularının radyoaktivite seviyesinin yüksek olmasına yol açmaktadır. İçme sularındaki radon konsantrasyonu değerlerinin ulusal veya uluslararası kuruluşlar tarafından belirlenmiş limitlerin altında bulunması istenir. Bu çalışmanın amacı; Afyonkarahisar il merkezinde halk tarafından çok sık kullanılan beş çeşmede radon konsantrasyonlarını ve yıllık ortalama etkin doz miktarlarını belirlemek ve mevsimsel değişimini incelemektir. Pylon AB-5R radon detektöründe yapılan analizler sonucunda elde edilen ortalama radon konsantrasyonu sonuçları ve ortalama etkin doz miktarları uluslararası kurumların tavsiye ettiği sınır değerleri ile karşılaştırılmıştır. Beş kaynağın ortalama radon konsantrasyonları 1,16 Bq/L ve 32,42 Bq/L aralığında, yıllık ortalama etkin doz değerleri ise 2,96 μSv/y ve 82,83 μSv/y aralığında belirlenmiştir. Radon, which constitutes approximately 50% of natural radiation sources; is a colorless, odorless, and radioactive heavy noble gas that cannot be detected by the sense organs. Radon and its decay products; It is formed as a result of a series of decays of radium and radium, the product of the radioactive decay series of the natural element uranium in rocks and soil. Radon is very easily soluble in water and organic solvents can travel long distances before it decays and causes the radioactivity level of groundwater to be high. Radon concentration values in drinking water are required to be below the limits determined by national or international organizations. This study aims to determine the radon concentrations and annual average effective dose amounts in five taps used frequently by the people in the province center of Afyonkarahisar and to examine the seasonal variation. The average radon concentration results and average effective dose amounts obtained as a result of the analysis performed in the Pylon AB-5R radon detector were compared with the limit values recommended by international institutions. The average radon concentrations of the five sources were between 1.16 Bq/L and 32.42 Bq/L, and the annual average effective dose values were determined between 2.96 μSv/y and 82.83 μSv/y.

RGAs are widely used in molecular component examination, impurity analysis, leak detection and test of vacuum system performance. However, RGAs have different sensitivities to different gases, and the sensitivities can change quickly and depend on so many parameters, which make its ability severely limited. In this work we established a new practical method to precisely measure noble gas ratio of argon -xenon gas mixture. Gaseous argon and xenon were controlled, respectively, by two mass flow controller (MFC). A variable leak valve (VLV) was used to introduce the gas mixture sample into the RGA measurement chamber. Gas mixtures with xenon concentration from 200ppm to 20000ppm (by mass) were introduced and tested by RGA. The time stability of RGA-measurement system was optimized to 2.1%. A good linearity of MFC-RGA response was achieved, verifying the reliability of RGA in measuring noble gas mixture with component concentration down to several hundred ppm level. Since the approach we used in our experiment is gas-species independent, we believe that it can be popularized to other gas species when properly applied.

Heavy noble gas (Ne, Ar, Xe) isotopic compositions provide powerful constraints on the nature of mantle heterogeneities. The North Atlantic popping rock sample 2ΠD43 is unusually gas-rich and has long formed the basis of our understanding of the noble gas composition of the mid-ocean ridge basalt (MORB) mantle source. Here we present new high-precision He, Ne, Ar and Xe isotopic compositions as well as He, Ne, Ar and Xe abundances measured in a split of the 2ΠD43 sample. After correcting the measured values for syn- to post-eruptive atmospheric contamination, we estimate a mantle source 21Ne/22Ne of 0.0590 ± 0.0002, 40Ar/36Ar of 23,900 ± 100 and 129Xe/130Xe of 7.41 ± 0.02 for 2ΠD43. Significant regassing of atmospheric Xe into the North Atlantic popping rock mantle source is evident, though differential regassing cannot explain systematic variations between MORB and plume-derived signatures. Rather, the fissiogenic Xe isotope signature of the 2ΠD43 mantle source indicates a greater extent of long-term degassing of the upper mantle relative to the plume mantle to explain heavy noble gas isotopic variations. The popping rock data also add to growing evidence that the MORB mantle differentiated from the reservoir supplying noble gases to plume sources within the first 100 Myr of Earth history, and that the two reservoirs have not been homogenized though 4.45 Ga of mantle convection.

The Qulong porphyry Cu–Mo deposit, generated in the Miocene post-collisional extension environment of the Gangdese Copper (Molybdenum) Metallogenic Belt, is one of the largest porphyry Cu deposits in China. This study reports the noble gas isotopic compositions of volatiles released from fluid inclusion reserved in pyrite from the Qulong deposit. 3He/4He and 40Ar/36Ar ratios range from 0.54 to 1.015 Ra and 300–359, respectively. Concentrations of 4He and 40Ar range from 1.77 to 2.62 × 10−8 cm3 STP and 1.7–34 × 10−8 cm3 STP, respectively. The isotopic composition of noble gases indicates that the ore-forming fluids of the Qulong Cu–Mo deposit were a mixture of fluid containing mantle component, which is exsolved from the porphyry magma, and crustal fluid characterized by atmospheric Ar and crustal radiogenic He. The δ34S values of pyrite and molybdenite range from − 0.52‰ to 0.31‰, with an average of − 0.12‰, indicating a magmatic origin. More mantle components were involved in the Cu–Mo deposit than in the Mo–Cu deposit in the Qulong-Jiama ore-district.

Offshore floating nuclear power plant (OFNPP) is a significant solution for marine electricity shortage. In this study, the optimized activated carbon for decay technology was studied in the experiment bench and engineering prototype respectively. The results show that ZLCYK001 activated carbon has better properties. The adsorption coefficient for krypton can be improved when the pressure is increased, the temperature and relative humidity are decreased and the flow velocity is controlled between 0.12 and 5 cm/s. The adsorption property has good reliability and stability in engineering prototype which is significant for the design and operation of the waste gas treatment system.

Understanding microstructural and strain evolutions induced by noble gas production in the nuclear fuel matrix or plasma-facing materials is crucial for designing next generation nuclear reactors, as they are responsible for volumetric swelling and catastrophic failure. We describe a multimodal approach combining synchrotron-based nanoscale X-ray imaging techniques with atomic-scale electron microscopy techniques for mapping chemical composition, morphology and lattice distortion in a single crystal W induced by Kr irradiation. We report that Kr-irradiated single crystal W undergoes surface deformation, forming Kr containing cavities. Furthermore, positive strain fields are observed in Kr-irradiated regions, which lead to compression of underlying W matrix.

Molecular dynamics simulations are conducted to investigate the effect of melting on energy accommodation coefficient (EAC) of Al-noble gas systems. The accommodation coefficients are computed for a gas temperature of 3000 K and slab temperatures in the range of 600-1500 K. Three different noble gases: helium, argon and xenon, are considered. Density functional theory (DFT) derived gas-metal interatomic potentials are used to obtain accurate predictions of accommodation coefficients. An abrupt jump in the accommodation coefficient upon melting is observed for argon and xenon, whereas the accommodation coefficient is negligibly affected for helium gas. The effects of gas-metal potential and gas atom mass are probed separately and it is found that the gas-metal potential has a negligible effect on the magnitude of EAC jumps. The gas atom mass, on the other hand, exerted a strong effect; heavier gases exhibited greater EAC jumps than lighter gases. The underlying physics is then unraveled by studying the effects of surface roughness and lattice dynamics on accommodation coefficient. Surface roughness increases the tangential EACs significantly for all gases, but the normal EACs are not as strongly amplified. Analysis of vibrational density of states of solid and liquid slabs suggests the activation of low frequency vibrational modes upon melting. This coupled with the roughening of surface upon melting results in an abrupt jump in the accommodation coefficient, especially for heavier gases.

Several studies based on in vivo or in vitro models have found promising results for the noble gas argon in neuroprotection against ischaemic pathologies. The development of argon as a medicinal product includes the requirement for toxicity testing through non-clinical studies. The long exposure period of animals (rats) during several days results in technical and logistic challenges related to the gas administration. In particular, a minimum of 10 air changes per hour (ACH) to maintain animal welfare results in extremely large volumes of experimental gas required if the gas is not recirculated. The difficulty with handling the many cylinders prompted the development of such a recirculation-based design. To distribute the recirculating gas to individually ventilated cages and monitor them properly was deemed more difficult than constructing a single large enclosure that will hold several open cages. To address these concerns, a computational fluid dynamics (CFD) analysis of the preliminary design was performed. A purpose-made exposure chamber was designed based on the CFD simulations. Comparisons of the simulation results to measurements of gas concentration at two cage positions while filling show that the CFD results compare well to these limited experiments. Thus, we believe that the CFD results are representative of the gas distribution throughout the enclosure. The CFD shows that the design provides better gas distribution (i.e. a higher effective air change rate) than predicted by 10 ACH.

We report new noble gas signatures of groundwaters, hot springs, and bedrock samples from two major fault systems that form the plate boundary suture between the Eurasian Plate and the Philippines ...

Simulation of the irradiation of crystalline silicon with low-energy (50—500 eV) noble-gas ions (He, Ne, Ar, Kr, Xe) is performed using the molecular-dynamics method with damage accumulation. The analysis of structural changes in the near-surface layers of the material demonstrates significant differences between the mechanisms of silicon damage by light and heavy particles. It is shown that, under material irradiation with Xe ions and especially with He ions, the largest clusters are formed by atoms implanted in the material.

Noble gas and nitrogen isotopic compositions of Karimati ordinary (L5) chondrite are presented. Aliquots of the meteorite were studied in two noble gas mass spectrometers. Its cosmic ray exposure (CRE) history, trapped noble gases and nitrogen isotopic systematic are examined. The compositions of Ne and Kr in this meteorite indicate presence of mixture of solar wind and Q trapped components. In addition to the primordial components, radiogenic 129Xe (from the decay of short-lived radioactive 129I) is observed in the two aliquots (129Xe/132Xe ranges between 1.054 and 1.311). The U/Th-4He and K-40Ar ages are discordant. U/Th-4He ages are younger than the K-40Ar ages, indicating loss of helium. The trapped N component is isotopically light analogous to Q gas/solar wind. The cosmic-ray exposure ages of the two aliquots are 16.1 ± 2.7 Ma and 16.6 ± 2.0 Ma based on the cosmogenic 21Nec and 38Arc concentrations.

A comparison is made of the ion-induced corrugation of the shell of carbon fibers reinforcing a KUP-VM composite upon high-fluence irradiation with $${\text{N}}_{2}^{ + }$$ and Ar+ ions with an energies of 10 to 30 keV at temperatures ranging from 100 to 600°C. Irradiation with noble gas ions is better for simulation of the neutron irradiation of graphite materials. Irradiation with nitrogen ions is preferable when modifying a carbon fiber surface.

Two-phase noble liquid detectors are widely used in experiments for dark matter search. Ionization signals caused by particle scattering in a noble-gas liquid are commonly recorded using the effect of proportional electroluminescence in the gas phase. In addition to the standard electroluminescence mechanism based on vacuum ultraviolet emission of noble gas excimers, the mechanism of electron bremsstrahlung on neutral atoms with a continuous spectrum from ultraviolet to near infrared range was recently revealed. In this paper, we demonstrate the effect of bremsstrahlung on characteristics of a DarkSide-50 two-phase argon detector. In particular, the sag of the electroluminescent gap grid and the contribution of the fast component to the proportional electroluminescence signal will be estimated.

The use of the noble gas radon ( 222Rn ) as a tracer for different research studies, for example observation-based estimation of greenhouse gas (GHG) fluxes, has led to the need of high-quality 222Rn activity concentration observations with high spatial and temporal resolution. So far a robust metrology chain for these measurements is not yet available. A portable direct atmospheric radon monitor (ARMON), based on electrostatic collection of 218Po , is now running at Spanish stations. This monitor has not yet been compared with other 222Rn and 222Rn progeny monitors commonly used at atmospheric stations. A 3-month intercomparison campaign of atmospheric 222Rn and 222Rn progeny monitors based on different measurement techniques was realized during the fall and winter of 2016–2017 to evaluate (i) calibration and correction factors between monitors necessary to harmonize the atmospheric radon observations and (ii) the dependence of each monitor's response in relation to the sampling height and meteorological and atmospheric aerosol conditions. Results of this study have shown the following. (i) All monitors were able to reproduce the atmospheric radon variability on a daily basis. (ii) Linear regression fits between the monitors exhibited slopes, representing the correction factors, between 0.62 and 1.17 and offsets ranging between −0.85 and −0.23 Bq m −3 when sampling 2 m above ground level (a.g.l.). Corresponding results at 100 m a.g.l. exhibited slopes of 0.94 and 1.03 with offsets of −0.13 and 0.01 Bq m −3 , respectively. (iii) No influence of atmospheric temperature and relative humidity on monitor responses was observed for unsaturated conditions at 100 m a.g.l., whereas slight influences (order of 10−2 ) of ambient temperature were observed at 2 m a.g.l. (iv) Changes in the ratio between 222Rn progeny and 222Rn monitor responses were observed under very low atmospheric aerosol concentrations. Results also show that the new ARMON could be useful at atmospheric radon monitoring stations with space restrictions or as a mobile reference instrument to calibrate in situ 222Rn progeny monitors and fixed radon monitors. In the near future a long-term comparison study between ARMON, HRM, and ANSTO monitors would be useful to better evaluate (i) the uncertainties of radon measurements in the range of a few hundred millibecquerels per cubic meter to a few becquerels per cubic meter and (ii) the response time correction of the ANSTO monitor for representing fast changes in the ambient radon concentrations.

The behavior of the surface of carbon fibers based on polyacrylonitrile, which reinforce the KUP-VM composite, upon corrugation under high-fluence irradiation with $${\text{N}}_{2}^{ + }$$ ions with an energy of 15 and 30 keV and a temperature of the irradiated composite in the range from 100°C to 600°C is described and discussed. In contrast to irradiation with ions of noble gases, it is found that the main parameters of the corrugated structure, such as the tilt angles of corrugations and their fractions on the surface of a fiber, are practically independent of the composite temperature. The corrugation periodicity is hundreds of nanometers, as in the case of irradiation with neon and argon ions. In the case of using ion energies of 15 and 30 keV, the tilt angles are 30° and 40°, respectively. The difference between the temperature dependences of the tilt angle of the corrugations and their fraction on the fiber surface and similar dependences in the case of irradiation with noble gas ions is determined by the peculiarities of the dynamic annealing of radiation-induced damage in the fiber shell due to the chemical activity of nitrogen associated with the creation of C–N bonds and a larger proportion of the amorphous component.

This Review deals with the evolving field of polyhalogen chemistry, specifically polyhalogen anions (polyhalides). In addition to a historical outline, current progress in synthetic approaches towards the formation of polyfluorides, polychlorides, polybromides, and polyinterhalides is also illustrated. The structural diversity of polyhalides has substantially increased in the past decade, especially for polychlorides and polybromides, which are commonly characterized by single-crystal X-ray diffraction, Raman spectroscopy, and quantum-chemical calculations. Polyfluorides have been examined by sophisticated state-of-the-art quantum-chemical calculations and investigated spectroscopically in noble gas matrix-isolation experiments under cryogenic conditions at 4 K. The bonding in such polyhalide systems is also discussed. The last Section deals with applications of polyhalides in halogenation reactions and electrochemistry as well as their use as reactive ionic liquids, emphasizing the promising future of polyhalogen chemistry.

Background The peak suppression effect, which suppresses the argon isotope signal due to the incomplete cleaning of gas from geological samples during measurement, is found in volatile-rich samples using the ARGUS VI noble gas mass spectrometer and its sample preparation system. Such effect hampers getting the precise isotope ratio essential for the 40Ar/39Ar age calculation. Findings The addition of one hot-getter and three room-temperature getters to the sample preparation system can effectively eliminate the peak suppression effect for several milligrams of sample during argon measurement to yield highly plausible 40Ar/39Ar ages of Quaternary volcanic rocks. Conclusions The modified preparation system makes it possible to get highly precise zero-time isotope signals, and thereby a geologically plausible 40Ar/39Ar age, especially for a small amount of volatile-rich samples.

We use a novel technique to solvate silver cations in small clusters of noble gases. The technique involves formation of large, superfluid helium nanodroplets that are subsequently electron ionized, mass-selected by deflection in an electric field, and doped with silver atoms and noble gases (Ng) in pickup cells. Excess helium is then stripped from the doped nanodroplets by multiple collisions with helium gas at room temperature, producing cluster ions that contain no more than a few dozen noble gas atoms and just a few (or no) silver atoms. Under gentle stripping conditions helium atoms remain attached to the cluster ions, demonstrating their low vibrational temperature. Under harsher stripping conditions some of the heavier noble gas atoms will be evaporated as well, thus enriching stable clusters Ng$_n$Ag$_m^+$ at the expense of less stable ones. This results in local anomalies in the cluster ion abundance which is measured in a high-resolution time-of-flight mass spectrometer. Based on these data we identify specific "magic" sizes n of particularly stable ions. There is no evidence though for enhanced stability of Ng$_2$Ag$^+$, in contrast to the high stability of Ng$_2$Au$^+$ that derives from the covalent nature of the bond for heavy noble gases. "Magic" sizes are also identified for Ag$_2^+$ dimer ions complexed with He or Kr. Structural models will be tentatively proposed. A sequence of magic numbers $n$ = 12, 32, 44, indicative of three concentric solvation shells of icosahedral symmetry, is observed for He$_n$H$_2$O$^+$.

Conventional DC magnetron sputter deposition from a carbon target with argon as the sputtering gas is limited by a low deposition rate, and the resultant coatings have low diamond-like sp3 content. Here we study arc-mixed mode high power impulse magnetron sputtering (HiPIMS) of carbon using He, Ne, Ar, Xe and Kr gases and show an increase in deposition rate is achieved by using noble gases heavier than argon. On the other hand, a higher sp3 fraction is achieved by using noble gases lighter than argon. The higher deposition rate of the heavier noble gases is attributed to the higher sputtering yield and an earlier arc onset owing to their lower ionization potential. The higher sp3 fraction achieved by lighter noble gases is attributed to stress generation by knock-on collisions at the surface of the depositing film, in the absence of stress relief created by large thermal spike volumes. When neon was used as the sputtering gas, the inert gas content was higher than for any other noble gas. Our results lead to opportunities for grading the sp3 content with depth simply by changing the gas composition, allowing fabrication of buried conductive channels in ta-C, Metal-Insulator-Metal (MIM) (low sp3/high sp3/low sp3) structures and biosensor films (high sp3/low sp3).

We established a new laboratory for noble gas mass spectrometry that is dedicated to the development and application to cosmogenic nuclides at the University of Cologne (Germany). At the core of the laboratory are a state-of-the-art high-mass-resolution multicollector Helix MC Plus (Thermo Fisher Scientific) noble gas mass spectrometer and a novel custom-designed automated extraction line. The mass spectrometer is equipped with five combined Faraday multiplier collectors, with 1012 and 1013 Ω pre-amplifiers for faraday collectors. We describe the extraction line and the automated procedure for cosmogenic neon and the current performance of the experimental set-up. Performance tests were conducted using gas of atmospheric isotopic composition (our primary standard gas), as well as CREU-1 intercomparison material, containing a mixture of neon of atmospheric and cosmogenic composition. We use the results from repeated analysis of CREU-1 to assess the performance of the current experimental set-up at Cologne. The precision in determining the abundance of cosmogenic 21Ne is equal to or better than those reported for other laboratories. The absolute value we obtain for the concentration of cosmogenic 21Ne in CREU is indistinguishable from the published value.

The present paper examines the luminescence of ternary Ar-Kr-Xe and Ne-Ar-Kr mixtures of noble gases in the spectral range from 300 to 970 nm, excited by the 6Li(n,α)3H nuclear reaction products in the core of a nuclear reactor. A thin layer of lithium applied on the walls of the experimental device, stabilized in the matrix of the capillary-porous structure, serves as a source of gas excitation. During in-pile tests, conducted at the IVG.1M research reactor, thermal neutrons interact via the 6Li(n,α)3H reaction, and the emergent alpha particles with a kinetic energy of 2.05 MeV and tritium ions with a kinetic energy of 2.73 MeV excite gaseous medium. The study was carried out in a wide temperature range. The temperature dependence of the intensity of the emission of the atoms of noble gases and alkali metals, heteronuclear ionic molecules of noble gases were studied. The obtained values of the activation energy of the emission process 1.58 eV for lithium and 0.72 eV for potassium agree well with the known values of evaporation energy. Excitation of alkali metals atoms occurs consequently of the Penning process of alkali metals atoms on noble gas atoms in the 1s-states and further ion-molecular reactions.

Noble gas plasmas are commonly used as ion and excitation sources in inductively coupled plasma (ICP) optical emission and mass spectrometry for organic and inorganic chemical analysis. However, the high power (∼kW) and voluminous gas flow rate (∼15 L min−1) of commercial plasmas limit their potential deployment in remote terrestrial and planetary environments. Here, using argon and helium gas supplies, we investigate the fundamental characteristics of low power and reduced-pressure microwave plasmas for organic and elemental analysis. These plasmas require a fraction of the power ( 99%) organic molecules or elements with high ionization potentials (e.g. glycine, 8.9 eV, or S, 10.4 eV); in comparison, helium can achieve similar performance metrics with as little as 5 W of forward power.

The exact first and second order partial derivatives of Shannon entropy density with respect to the number of electrons at constant external potential are introduced as new descriptors for prediction of the active sites of a molecule. The derivatives, which are a measure of the inhomogeneity of electron density, are calculated both exactly (from analytical forms) and approximately (using the finite difference method) for some molecular systems. According to the maximum entropy principle, the extreme value of the first order derivative on the surface of a given molecule should determine the active sites of the molecule in electrophilic and nucleophilic attack. The second order derivative indicates where the Shannon entropy is more concentrated or depleted during the electron exchange. Although these derivatives on the surfaces of helium and neon atoms are uniform, the corresponding values for argon, krypton and xenon atoms are not. This could explain the greater tendency of heavy noble gas atoms to form stable compounds. A dual descriptor is also defined as the difference between the left and right first order derivatives of Shannon entropy density, which allows one to simultaneously predict the preferable sites for electrophilic and nucleophilic attack over the system at point r. Therefore, the reactivity of an atom in a molecule requires the non-uniformity of the first and second order derivatives of Shannon entropy density on the surface of that atom.

The regularities of surface corrugation of polyacrylonitrile based carbon fibers reinforcing composite KUP-VM has been studied experimentally after high-fluence 30 keV Ne+, 20 and 30 keV Ar+, 30 keV N2+ ion irradiation at target temperatures ranging from 100 to 600 °C. It was found that periodic corrugated structure parameters, such as the angles of the inclination β of the corrugations and their fraction on the fiber surface have strong temperature dependences. The periodicity of corrugations for all used ions slightly decreases with increasing temperature and is of the order of hundreds of nanometers. For neon and argon ions the corrugation inclination angles and the fraction in contrary of nitrogen ions show minima at the temperatures near 400 °C which corresponds to the minimum of radiation-induced dimensional changes in carbon materials. The depth of the minima at 400 °C depends on the competition of the processes of ion-induced plastic deformation of carbon materials and ion bombardment sputtering. For nitrogen ions the inclination angles increase with temperature so that at temperature ∼270 °C they reach maximum values ∼40°, staying at this level at subsequent temperature elevation up to 600 °C. The qualitative difference in the temperature dependences of fiber corrugation for noble gas ions and nitrogen ones is connected to nitrogen chemical activity and the creation of C N bonds under nitrogen ion implantation.

Due to the momentum and energy exchange between the gas and solid surface molecules, by means of the accommodation coefficients in the Cercignani-Lampis-Lord (CLL) model, the velocity components used in the Direct Simulation Monte Carlo (DSMC) method can be studied more accurately. The coefficients can also be used in calculation of slip velocity, temperature jumping, drag force and shear stress. In the light of rising needs for polymers in industrial applications, the scattering behavior of noble gas molecules in their collision with a surface made of diglycidyl ether bisphenol A (DGEBA) epoxy resin, cured by tetrahydrophthalic anhydride (THPA) agent and reinforced by multi-layer graphite, was simulated and investigated by Molecular Dynamics (MD). The momentum and energy accommodation coefficients for gas–surface interactions were also calculated by MD simulation. The results indicated that temperature increase, change in the gas species, reduction in surface roughness, and increase in the Knudsen number ( Kn ) and the wall velocity could cause the accommodation coefficients to be less than one. Based on the scattering kernel of CLL boundary condition, a suitable distribution function for calculating the velocity components of noble gas molecules (e.g., argon molecules) after interaction with polymeric surface was proposed.

Henry’s law constant data for the noble gases helium, neon, argon, krypton, xenon, and radon in the pure solvents water, methanol, ethanol, and propan-2-ol are predicted over a wide temperature range by molecular simulation. Furthermore, gas solubility measurements are carried out for neon, krypton, and xenon in propan-2-ol, yielding experimental Henry’s law constant values that are employed, together with data from the literature, to evaluate present simulation results. Suitable molecular force field models are identified for each binary system, and new models for helium and neon are presented. By examining the entire set of binary systems, a characteristic trend of the solubility behavior concerning the molecular size of the solutes and solvents is identified. The present work contributes consistent Henry’s law constant data for 24 binary solute–solvent pairs over the entire relevant temperature range and improves the database considerably.

Limited reserves and insecure resource supply have led to global shortage crises in helium, a vital gas for cryogenic engineering and other countless industrial manufacturing processes. Despite the attention drawn by global supply disruptions, the helium accumulation mechanism in natural gas fields remains poorly understood. Noble gases are excellent tracers for studying migration and accumulation processes of fluids in the subsurface and can be used to investigate the influence of subsurface fluids on helium accumulation. We present noble gas isotope and abundance data as well as major gas compositional data from 10 producing wells in three gas fields in the North Qaidam Basin, China. Helium is more concentrated in the Mabei and Dongping gas fields (2.06–48.4 × 10−4 cm3 STP/cm3) than in the Niudong gas field (1.15–1.42 × 10−4 cm3 STP/cm3). The helium is mainly radiogenic, with 3He/4He ratios of 0.01–0.05 Ra, where Ra is the atmospheric value of 3He/4He, and lacks significant contribution from the mantle (0.03–0.67%). The noble gases derived from air-saturated water (20Ne, 36Ar, 84Kr and 130Xe) can be explained by an oil-modified groundwater-exsolution model with excess heavy noble gases. The calculated Voil/Vwater and Vgas/Vwater ratios indicate that the Mabei region is the most oil-rich area and the Dongping region has the driest natural gas, which is consistent with the geological context. These ratios further support the fractionation models. The strong linear relationship between 4He and 20Ne (R2 = 0.98) suggested that 4He was dissolved into groundwater before migrating into the oil or gas phase. The initial 4He concentrations in groundwater can accumulate within 0.31–2.78 Myr assuming a 4He flux from the entire crustal section. According to the fractionation model, helium in groundwater partitions into the gas phase when contacting hydrocarbons. The different volume ratios among oil, gas and water during the equilibration process cause much greater variability in the helium concentrations in the gas phase (e.g., 6.08 × 10−4 to 2.01 × 10−3 cm3 STP/cm3 in Mabei) than those in the groundwater phase (e.g. 9.18 × 10−3 to 1.39 × 10−2 cm3 4He STP/cm3 H2O in Mabei). Hydrocarbons play a critical role in helium accumulation and dilution. Helium-rich natural gas fields are characterized by old groundwater systems and moderate hydrocarbon abundance. This study has succeeded in quantitatively assessing the helium accumulation process in natural gas fields in the North Qaidam Basin and revealed that both groundwater and hydrocarbon phases control the helium accumulation in the subsurface environment. This outcome has broad implications for the prediction of hydrocarbon and helium as resources.

The noble gas radioisotopes 85Kr, 81Kr, and 39Ar are nearly ideal environmental tracers because of their chemical inertness and simple transport mechanisms. Recent advances in Atom Trap Trace Analysis have enabled measurements of 85Kr and 81Kr using 10-20 kg of water or ice, and 39Ar in only a few kilograms, making these tracers available to be applied in the earth sciences on a large-scale. To meet the resulting increase in demand, we have developed an automated process for the dual separation of krypton and argon from environmental samples based on titanium gettering and gas chromatography. 0.5-4 L STP air samples have been purified, demonstrating purities and recoveries of >90% for krypton and >99% for argon within 90-120 min of processing time. Samples of high methane admixtures, a challenge regularly encountered in groundwater applications, have been purified by exploiting the full potential of titanium gettering at high temperatures (>1000 °C). Samples with 0.4-48 L STP of methane admixture are processed in 2-5 h without compromising purity or recovery. The applicability of the purification system is further demonstrated using actual groundwater samples with carbon dioxide and methane content in the extracted gas up to 16 L STP and 42 L STP, respectively.

The article presents the classification of the gas stream contaminant types in noble gas enrichment and purification units. For the safe and efficient system operation, it is necessary to choose the right method of multicomponent mixture separation and the optimal corresponding equipment operating parameters, also to offer a method to verify the absence of the undesirable contaminant in the gas stream. The methods to control the obtaining of required noble gas purity during cryogenic rectification are indicated. Application of various gas analysis methods is necessary to obtain high purity (up to 99.9999%) gases: gas chromatography, mass spectrometry, and their combination. The effect of the state of various components of a gas chromatograph on the analysis result are discussed. Recommendations are provided for noble gas analysis methodology, including the conditions for the determination of trace impurities. The article presents examples of practical application of gas chromatography to control the processes of noble gas enrichment and purification, using the example of production of pure xenon.

International audience; The origin and evolution of terrestrial volatiles is a fundamental question in Earth and planetary sciences. To better address this, it is necessary to estimate the present-day isotopic and elemental composition of volatiles in the mantle, which is difficult because degassing during magma transport to the surface changes the initial elemental composition. However, some basalts are considered to be relatively un-degassed and therefore can be used to determine the concentrations of C, N, H2O and noble gases in the mantle. This is the case of the so-called popping rock sample 2πD43, found near 14 °N on the Mid-Atlantic Ridge in 1985, which has been considered as a reference for upper mantle isotopic and elemental volatile compositions due to its high gas content. Such gas-rich samples have been recovered in only a few places on mid-ocean ridges but are crucial to characterizing the heterogeneities in mantle composition and therefore the cycling of volatiles on Earth. In order to better understand the occurrence of popping rocks, mantle heterogeneities and volatile cycling on Earth, cruise AT33-03 on R/V Atlantis was conducted in 2016 on the Mid-Atlantic Ridge near 14 °N. Popping rocks were found in the same area as sample 2πD43, using the submersible Alvin, and their noble gas compositions were determined by step-crushing and laser ablation. A new anaerobic sampling protocol was tested in an attempt to minimize atmospheric contamination, which is ubiquitous in basaltic glass samples used for noble gas analyses, and to evaluate laser extraction techniques. Preliminary step-crushing results suggest that the new anaerobic sampling protocol reduces atmospheric influence on the noble gas measurements. Comparison with laser ablation data shows that there is still some atmospheric contamination, suggesting that contamination begins on the seafloor. Two groups of samples have been identified based on their noble gas compositions: one group with their highest measured ratios similar to those of sample 2πD43 (20Ne/22Ne of ~ 12.5, 40Ar/36Ar of ~ 27,000), and another group with lower maximum noble gas ratios (20Ne/22Ne of 12.2, 40Ar/36Ar of 16,100) and higher argon concentrations. Based on these results, along with Cl/K and H2O/Ce ratios and preliminary lead, strontium and neodymium isotope data, it is suggested that these two groups of samples reflect separate eruptive events that originated from distinct mantle sources. This provides evidence for upper mantle heterogeneity at small scales and could imply that the mantle source with lower neon and argon isotopic ratios has been more influenced by recycling of atmospheric noble gases.

Studying the initial stages of surface oxidation is of great relevance to understand how oxygen alters the physical and chemical properties at the interface of the host material to the environment and is therefore, crucial for improvement in manifold technological applications. We investigated the influence of surface oxygen on ion spectra recorded for keV noble gas ions backscattered from metal surfaces in low energy ion scattering (LEIS). Initially pure Zn and Ta surfaces, chosen for their well-characterized properties in ion-neutralization in LEIS, have been oxidized and ion spectra for pure and oxidized surfaces have been compared. Oxygen on the surface significantly influences shape and intensity of the backscattered ion spectrum at all energies: for both metal systems, the surface scattered ion yield of the metal is drastically decreasing under oxygen presence. The observed decrease, however, cannot be explained by the reduction in the surface areal density of the metal constituents exclusively. At least for Zn an additional significant change in charge exchange behavior is necessary to explain the observations. In contrast to the generally observed decrease in the yield of ions scattered from the outermost surface, the change in shape and intensity of the reionization background are found to show opposing trends and different energy dependencies for Zn and Ta.

The sensitivity of planar multijunction thermal converters was significantly increased by filling the housing with noble gasses, preferably xenon or krypton. The performance was observed for almost two years, and no degradation of the sensitivity was found. Also, the frequency response of the ac–dc transfer difference remains unchanged at high frequencies and even improves below 40 Hz. Using the lowest at present manufacturable heater resistance of 90 $\Omega $ with the noble gas filling, ac–dc transfer at voltages down to almost 70 mV compared to about 100 mV in air becomes possible.

We have determined the concentrations of atmospheric helium, neon, argon, krypton , and xenon in distilled water and seawater equilibrated with moist marine air at one atmosphere over a temperature range from near freezing point to approximately 35 °C and a salinity range of zero to roughly 39.5 PSS78. In all, we made 74 sets of noble gas measurements at 34 distinct temperature and salinity combinations. The experiments included 35 replicate pairs of samples drawn from 35 separate equilibrations, which in turn had three pairs of repeat equilibrations run at close to identical temperatures. We fit the results to an eight-parameter function similar to one commonly used to compute solubility equilibrium concentrations of these gases for environmental waters. Based on an estimate of analytical accuracy, reproducibility of the comparison with secondary atmospheric standards, replicate sample reproducibility, and reproducibility of the repeat equilibrations, we estimate this function to predict equilibrium concentrations at a particular temperature and salinity within this range to overall precisions 0.10% or better. This includes the regression statistics associated with interpolation and analytical errors for fitting the 8-parameter smoothing function. There is an overall systematic uncertainty of 0.15% for all gases, based on our confidence in and experience with the integrity and cross-calibration of our air standards over recent years. Because our methods are calibrated using assumed and explicit atmospheric abundances of these noble gases, any subsequent uncertainties in atmospheric abundances cancel out in the determination, particularly when the oceanographic measurements utilize marine air as a primary standard. Furthermore, measurement at ambient atmospheric abundances avoids any potential co-solvency induced biases introduced by using ~1 atm pure noble gases, as has been done in most previous studies. We compare these determinations to those made by others in the past and find modest but significant systematic differences with those results.

Atmospheric radioactive noble gas radon (Rn-222) originates from soil gas exhaled in the atmospheric surface layer. Radon exhalation rates from soil as well as corresponding meteorological and soil parameters were recorded for two subsequent years. Based on long-term field data, a statistical regression model for the radon exhalation and the most important influencing parameters soil water content, temperature of soil and air, air pressure and autocorrelation of the exhalation rate was established. The fitting result showed that the multivariate model can explain up to 61% of the variation of the exhalation rate. First, the exhalation rate increases up to 80 Bq m(-2) h(-1) with increasing soil water content. Later, at water content N10%, increasing soil wetness suppressed the exhalation rate: at values higher than 24% to approximately one third. The air temperature had a distinct positive effectwhile the soil temperature had a strong negative effect on the exhalation rate, indicating their different influencing-mechanisms on the exhalation. The air pressure was negligible. The lagged values of radon exhalation had to be included in the model, as the variable shows strong autocorrelation. (c) 2018 Elsevier B. V. All rights reserved.

Research results of luminescence spectra of noble gases and Ar–Xe, Ar–Kr, and Kr–Xe mixtures under the excitation by products of nuclear reaction in the core of a stationary nuclear reactor with 0.87 × 1014 n/cm2s thermal neutron flux are described in the article. The emission spectra of noble gases are similar to the obtained spectrum under the excitation by the 40Ar+7 ion beam from the DC-60 accelerator. Bands in spectra of the binary mixtures of noble gases are connected with the radiation on heteronuclear ion molecule transitions. The appearance of the lines of alkali metal atoms at the temperature increase of gas chamber is explained by sputtering of the lithium layer via nuclear reaction products as well as ionized and excited particles of the buffer gas.

The diffusion of noble gas argon in the near-surface region of rutile TiO2 has been explored with the Temperature Programmed Out-Diffusion (TPOD) method. The Ar atoms were deposited in a several-nanometer-deep layer of the single-crystal TiO2(110) surface by bombardment with 1–5 keV energy Ar ions. Subsequently, in the TPOD experiments this sample was heated at a linear rate and the out-diffusion of argon was monitored with a mass-spectrometer. Surface conditions were probed with Auger Electron Spectroscopy (AES) and Low-Energy Electron Diffraction (LEED). The experimental results were analyzed with the aid of numerical simulations. The measurements showed a dependence of the Ar diffusion rates on the concentration of buried argon and composition of the surface layer. The kinetic parameters of Ar diffusion in pristine rutile TiO2 were estimated as Ea = 104 kJ/mol and D0 = 6 ⋅ 10−9 m2/s. A distinctive diffusion regime, related to the rock salt TiO phase formation, were identified.

Natural gas reserves with 0.3–2 mol% helium are considered as the only viable source for this noble gas. Currently, cryogenic separation is used to extract helium, but it is energy-intensive. While membrane-based separation is a promising alternative, it is still not considered economical. Even for an inorganic/silica membrane with relatively high selectivity and permeance, a multi-stage membrane system with inter-stage compression is required, which necessitates high CAPEX and OPEX. This study proposes a novel process to enhance the selectivity and permeance of an inorganic/silica membrane system to eliminate the costly inter-stage compression. A 16–24% reduction in the CAPEX and 23–57% in the OPEX are achievable for a natural gas feed with 3–5 mol% helium. In contrast, for a 2 mol% helium feed, the OPEX increases by 34%. However, a 30% decrease in the capital cost outweighs the OPEX increase to make the new process more profitable.

A major challenge in the design of heat shields for atmospheric entry probes for Saturn, Uranus, and Neptune lies in the modeling of the thermochemical non-equilibrium shock layer. With proposed entry velocities into these H2/He atmospheres of above 20 km/s, the high temperatures in the shock layer will lead to the dissociation of H2, followed by H atom ionization, as well as associated radiation which results from internal energy excitation and the subsequent relaxation. These non-equilibrium processes can greatly affect the heating environment, as chemical reactions can alter the flow density and temperature which can influence convective heating, whereas radiation can act as another form of heating and energy loss from the flow. Despite much progress in the past, there are still significant uncertainties in numerical modeling of these non-equilibrium shock layers, especially regarding chemical reaction mechanisms. Due to the entry velocity and density being beyond the performance envelopes of most ground testing facilities, and the time and cost for a flight test being excessively high, there is a lack of data needed for a better understanding of this non-equilibrium shock layer.The X2 facility at the University of Queensland is a super-orbital expansion tube which can enable a wide range of measurements to be conducted for planetary entry conditions. However, freestream flows can only be generated with the speeds up to 21 km/s, which is not enough to simulate Saturn, Neptune, and Jupiter entry conditions directly. In 1998, a test gas substitution was proposed to simulate the non-equilibrium shock layer during these entries with a shock speed achievable in expansion tubes. Test gases with a higher fraction of helium than in these planets' atmospheres or using neon to substitute for helium as the inert diluent of hydrogen were used to simulate the entry atmosphere. Such heavier test gases will have a lower specific heat, and thus the facility performance and energy required to recreate the appropriate post-shock temperatures will be decreased. The primary ionized content in these flow is H+, with small amounts of ionization of the third body noble gas constituents, which act primarily as chemically inert body collision partners for dissociation and ionization, and to determine the overall post-shock temperatures encountered. Thus, the test gas substitution will not greatly alter the reaction mechanisms. The use of neon at the higher enthalpies corresponding to Jupiter entries does invoke some neon ionization, which has to be considered in evaluating the experimental data. This makes it possible for impulse facilities to simulate giant planet entries within their performance envelopes. Such a substitution method has been used to generate heavily ionizing flows as described in the literature, but has never previously been experimentally validated by radiation measurements.The purpose of this project was thus to use X2 to experimentally validate the substitution at a condition that was achievable using both helium and neon diluents and then to investigate the non-equilibrium shock phenomena that are expected during giant planet entries. Firstly, spectroscopic data were obtained by using an existing X2 condition that was designed to recreate the post-shock temperature of Saturn entry by increasing the mole fraction of helium in the H2/He test gas. The data obtained showed that a non-equilibrium shock layer with a slow ionization rate was generated. These phenomena are consistent with Saturn entry test data in the literature, thus qualitatively validating the helium enhancement substitution method. Compared to H2/He test gases, the substitution with neon can achieve a lower specific heat of the test gas and can be used to generate hotter shock layers with the same facility performance. To validate the substitution with neon, this H2/He condition was used as a reference, and a condition with H2/Ne test gas was designed to recreate the non-equilibrium shock layer generated by the H2/He condition. The controlling factors of chemical reaction rates in H2/inert mixtures including dissociation and ionization rates of hydrogen were investigated, and an H2/Ne condition was designed by duplicating the major controlling factors in the H2/He condition. The stream-wise development of the relaxation dependent parameters gave similarity when defined in terms of an appropriate binary scaled unit. Both conditions were tested in X2 and spectroscopic data were obtained. The experimental data showed that the designed H2/Ne condition successfully recreated the non-equilibrium processes generated by the H2/He condition, and quantitative agreement was obtained in the binary scaled radiation data. This experimentally validated the substitution of using neon to substitute helium in the test gas in terms of simulating shock layer relaxation and the associated radiation.A final series of experiments were conducted to obtain the electron number density generated by the H2/He condition based on Stark broadening. The calculated electron number density was compared with computational fluid dynamic calculations using two sets of reaction rate from the literature. Qualitative agreement was found between experimental data and numerical simulations using one of the selected rate sets. This indicates that one existing reaction kinetic model can be used to describe the shock layer chemistry well within the limits of the data that were measured. Whilst acknowledging that the full reaction mechanism is much more complex that the simple single temperature model would imply, it is seen to give a useful representation of the macroscopic phenomena at the conditions studied. Furthermore, it was found that, after adjusting one of these two rate sets by maintaining the dissociation rates and increasing the ionization rate coefficients by a factor of 25, the measured electron number density profile can be quantitatively simulated. This adjusted rate set was also cross-validated with similar measurements for Saturn entry from the literature, and good agreement was observed between experimental data and numerical predictions.This project is the first time that the test gas substitution theory has been validated in the context of radiation measurements. Previous work studied the effects of ionization through blunt body shock standoff distances on simulated ionizing flows using this substitution. This study extended the work by means of quantitative radiation measurements, and experimentally validated the substitution by a direct comparison of radiation data in a region where the facility simulation capabilities by using H2/He and H2/Ne test gas overlap. The combined conclusions of this and the preceding work implies that giant planet shock layers can be robustly scaled and simulated in expansion tubes using the test gas substitution for both the macroscopic shock layer details and the contained radiating flow fields. The outcome of this project will lay the groundwork for future giant planet entry studies, which enables a broader range of blunt body measurements to be performed for better numerical modeling. Additionally, this project provides unique new benchmark test data and an updated reaction rate set for further numerical model improvements in simulating giant planet entry phenomena.

The therapeutic effects of atmospheric pressure plasma jets (APPJs) have been associated with the presence of reactive species, mainly the reactive oxygen and nitrogen ones, generated in this kind of plasmas. Due to that, many studies attempting to enhance the production of reactive species in APPJs have been performed. The employment of gas admixtures, usually mixing a noble gas with oxygen (O2) or water vapor, is one of the most common methods to achieve such goal. This work presents a study of how the addition of small amounts of O2 affects the electrical parameters and the production of reactive species in a transferred APPJ produced at the tip of a long and flexible plastic tube. The study was carried out employing helium (He) as the working gas and applying a high voltage (HV) in the form of amplitude-modulated sine waveform (burst mode). With this configuration it was possible to verify that the O2 addition reduces the discharge power and effective current, as a result of late ignition and shorter discharge duration. It was also found that the addition of O2 to a certain content in the gas admixture makes the light emission from oxygen atoms increase, indicating an increment in oxygen related reactive species in the plasma jet. However, at the same time the light emitted from hydroxyl (OH) and nitric oxide (NO) exhibits the opposite behavior, i.e., decrease, indicating a reduction of such species in the APPJ. For these reasons, the addition of O2 to the working gas seems to be useful for increasing the effectiveness of the plasma treatment only when the target modification effect is directly dependent on the content of atomic oxygen.

Purpose of review To summarize the current data on neuroprotection derived by noble gas treatment focusing on xenon and argon. Recent findings Both xenon and argon have demonstrated neuroprotective properties in an array of disease models. However, current data for argon after traumatic brain injury (TBI) is conflicting. Recent human data is only available for xenon showing some beneficial aspects (fewer adverse events) but no effect on outcomes, such as incidence of postoperative delirium. Summary Promising results are available for neuroprotection derived by noble gas treatment. Results for xenon are more consistent than those for argon. The mechanism of action of xenon (noncompetitive NMDA-receptor inhibition) is also better understood compared with that of argon. The evidence for argon's neuroprotective actions (particularly after TBI) remains uncertain.

Recent years, we have seen the development of many fields of gas detectors. The MICROMEGAS (Micro-Mesh Gas Structure) appeared as the very promising detector. It is a major family of position detectors in High Energy Physics. This work is done in normal (NTP) based gas mixtures: neon are noble gas and isobutane and DME (dimethyl-ether) as moderators’ gas (quenchers), using 55Fe as a radiation source (X-ray 5.9 keV). To address the modeling of MICROMEGAS detector, a descriptive model of different physical and geometrical phenomena MICROMEGAS was established by developing a simulation program to spreading the detector response. After, an analytical calculation of the potential and the electric field distribution has been presented briefly to better estimate electrical and geometric configuration. Thereafter, simulation results of electrical signals based on gas mixtures (Neon-isobutane, Neon-DME) produced by MICROMEGAS were presented. Finally, our MICROMEGAS Detector is equivalent to a current generator low signal that is why; we need an amplification device to be able to clarify the quantitative calculus. These results of amplified signal were presented and analyzed in order to improve the MICROMEGAS performance (spatial (12 µm) and temporal (0.7 ns) resolutions).

A high throughput system for processing and detection of low levels of radioxenon in soil gas samples has been developed. Processing and analysis of sub-soil noble gas samples puts high demands on the gas separation part of the system since the samples might contain high levels of Rn, CO2 as well as other gases. The gas process is optimized to remove all CO2, H2O and Rn with a high recovery yield of the xenon in the sample to ensure a high sensitivity even for small samples. The system is designed to handle multiple samples per day with a high level of automation and sample traceability to be suitable for use in an on-site inspection (OSI) an important component in the verification of the Comprehensive Nuclear Test Ban Treaty. To ensure a rapid deployment the system could be pre-installed in a flight container.

Radon and thoron progeny are important contributors to dose from naturally occurring radionuclides, especially in high background areas and with naturally occurring radioactive material (NORM) legacy sites. Due to the short half-life of thoron, measurements of thoron progeny with a longer half-life should be used for risk and dose assessment. Deposition-based alpha track detectors for such progeny are, however, biased by air movement, especially outdoors where winds may be strong but variable. We used deposition detectors for thoron progeny and radon progeny, as well as alpha track gas detectors for 220Rn and 222Rn, outdoors within the Fen complex in Norway, an area with both elevated levels of naturally occurring radionuclides and NORM legacy sites. Different detector types were used and showed different results. We measured airflow along deposition detectors during deployment to assess wind bias and used statistical models to attain location-specific sheltering factors. These models assess how explanatory terms like point measurements with anemometer, predicted airflow along detectors, and levels of 220Rn and 222Rn explained variation in deposition detector measurements of TnP and RnP. For all the detector types, unrealistically, high equilibrium values (F) were found between progenitor noble gas and progeny before correcting for wind bias. Results suggest a magnitude of wind bias on TnP deposition detectors being a fraction of 0.74–0.96 (mean: 0.87) of the total measurement.

Volatiles and refractories represent the two end-members in the volatility range of species in any surface-bounded exosphere. Volatiles include elements that do not interact strongly with the surface, such as neon (detected on the Moon) and helium (detected both on the Moon and at Mercury), but also argon, a noble gas (detected on the Moon) that surprisingly adsorbs at the cold lunar nighttime surface. Refractories include species such as calcium, magnesium, iron, and aluminum, all of which have very strong bonds with the lunar surface and thus need energetic processes to be ejected into the exosphere. Here we focus on the properties of species that have been detected in the exospheres of inner Solar System bodies, specifically the Moon and Mercury, and how they provide important information to understand source and loss processes of these exospheres, as well as their dependence on variations in external drivers.