Kr Xe Mixtures Research Articles

Study of Luminescence in Noble Gases and Binary Kr-Xe Mixture Excited by the Products of 6Li(n,α)T Nuclear Reaction

At the present time the direct nuclear energy conversion into optical radiation is realized in gas media in which filling of energy levels takes place in the low-temperature plasma (nuclear-excited plasma) induced by ionizing radiation. The research of optical radiation of the nuclear-excited plasma induced by products of nuclear reactions is interest for development of an alternative outlet method of energy from the nuclear reactor, creation of control and regulating bodies for parameters of nuclear reactors as well as creation of one of diagnostics of high-temperature plasma in fusion reactors. The purpose of this work was to obtain new experimental data about processes of nuclear energy conversion into optical radiation with the optimal gas media having high coefficient of nuclear energy conversion into optical radiation and also with a possibility of outlet method of energy from the nuclear reactor core. In this article, description of the reactor experimental bench (LIANA) and the experiment scheme, the irradiating ampoule device (AD) with surface source of charged particles is provided, and the procedure of reactor experiment is presented. This paper presents the results of the reactor experiments of studying the spectral-luminescent characteristics of unary noble gases (Ne, Ar, Kr, Xe) and binary Kr-Xe gas mixture in a 200–975 nm spectral range with ionization gaseous media by products of 6Li(n,α)T nuclear reaction under irradiation at research water-cooled heterogeneous reactor (the IVG.1M).

Emission of noble gases and their mixtures with lithium excited by the products of the 6Li(n,α)3H nuclear reaction

AbstractResearch 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.

Luminescence of Noble Gases and Their Mixtures Under Nanosecond Electron-Beam Excitation

Luminescence spectra in the range 200–970 nm were studied for He, Ne, Ar, Kr, and Xe and Ar–Kr, Ar–Xe, and Kr–Xe mixtures under 5-ns electron-beam excitation. Emission intensity distributions over noble-gas 2p-levels were obtained. It was concluded that the main process for populating atomic levels was not dissociative recombination of molecular noble-gas ions with electrons. The emission intensity of heteronuclear ionic noble-gas molecules was noticeably less (relative to the intensities of the atomic lines) than for ion-beam excitation.

СЕБЕСТОИМОСТЬ ПОЛУЧЕНИЯ ОБОГАЩЕННОЙ КРИПТОНОКСЕНОНОВОЙ СМЕСИ

The estimation of the production cost price of enriched Kr-Xe mixture when it’s manufactured as a waste product by air separation units (ASU) is a challenging task. The comparison of calculating the cost price well-known methods was carried out and the main sources of the mixture expenditures for the production were analyzed. The «energy method» formulated by professor V.M. Brodyansky has been chosen for the calculation of the cost price. This method involves sharing costs between products according to their volume flow, taking into account the state of the energy flow at the outlet of the unit. The object of the research is the oxygen of the largest metallurgical enterprise. The object of the research is the oxygen production of a large iron and metal enterprise. The expenditures on the obtainment of the Kr-Xe mixture in a krypton column which is a part of the ASU have been calculated. The components of the cost price of the Kr-Xe concentrate which is manufactured in units of the “Chrome” type have been investigated.

Economic aspects of the Kr-Xe mixture production and enrichment

The present work deals with studying the structure of costs for extracting krypton-xenon mixture, produced as a byproduct of separation of air and krypton-xenon concentrate after its enrichment in individual plants. Reducing the costs of manufacturing products allows to reduce their prime cost and therefore increase the profits of the enterprise.As the object of investigation, oxygen production of large metallurgical enterprise was considered. Comparison of the known methods for calculating the prime cost of air separation byproducts was conducted, the main sources of costs for producing krypton-xenon mixture was analyzed. Components of the prime cost of krypton-xenon concentrate, produced during its enrichment in “Chrome”-type plants were investigated.Calculations have shown that energy costs (70-80 % of total costs) make the main contribution to the prime cost of the krypton-xenon mixture, produced in air separation plants. General production equipment maintenance costs and expenses constitute 20-30%. Contribution of wages fund is from 2 to 5%, depending on the wage level, adopted in the metallurgical industry.In enriching the krypton-xenon primary mixture in “Chrome”-type plants, energy costs (60% of all expenses) are also determining. Among them, 7% accounts for the production krypton-xenon concentrate compression. Wages are about 17% of total costs. Share of original Kr-Xe mixture in the prime cost of concentrate is about 9%.Studies have allowed to define “critical” items of expenses, changing which most affects the prime cost of intermediate mixtures and, finally, krypton and high-purity xenon sales profit margin.

Adsorption and separation of binary mixtures of noble gases on single-walled carbon nanotube bundles

Adsorption and separation of binary mixtures of noble gases including Argon (Ar), Krypton (Kr), and Xenon (Xe) on (10,10) single-walled carbon nanotube (SWCNT) bundles is simulated by extensive equilibrium molecular dynamics (MD). Adsorption energies, diffusion coefficients, activation energies, and radial distribution functions (RDFs) were calculated to address the thermodynamics, transport and structural properties of adsorption process. The simulation results of exposing Ar–Kr, Ar–Xe, and Kr–Xe mixtures on (10,10) SWCNT bundles at temperatures of 75, 150, and 300 K, show that amount of adsorption is strongly influenced by the applied temperature. On the other hand, RDF plots show obviously that separation of binary gaseous mixture is occurred, where the heavier noble gas is adsorbed more than the lighter one in a selective manner by bundle. It is seen that the increase in the applied temperature results in more separation. These findings provide us a possible application of carbon nanotubes (CNTs) as efficient nanomaterials for separation and storage of gas mixtures.

Adsorption behavior of ternary mixtures of noble gases inside single-walled carbon nanotube bundles

In order to study the gas-storage and gas-filtering capability of carbon nanotube (CNT) bundles simultaneously, we considered the adsorption behavior of a ternary mixture of noble gases, including Argon (Ar), Krypton (Kr), and Xenon (Xe), i.e., Ar–Kr–Xe mixture, on (10, 10) single-walled carbon nanotube (SWCNT) bundles. Molecular dynamics (MD) simulations at different temperatures of (75, 100, 150, 200, 250, and 300) K were performed, and adsorption energies, self-diffusion coefficients, activation energies, and radial distribution functions (RDFs) were computed to analyze the thermodynamics, transport and structural properties of the adsorption systems. It is observed that the SWCNT bundles have larger contents of heavier noble gases compared to the lighter ones. This interesting behavior of SWCNT bundles makes them proper candidates for gas-storage and gas molecular-sieving processes.

A UV lamp based on a Kr-Xe mixture with Br2 and I2 molecules

A small-size broadband ultraviolet lamp with an emission spectrum of 206–390 nm, which is excited by a dc glow discharge, is described. The discharge was ignited in a quartz discharge tube with an inner diameter of 1.4 cm and an anode-cathode spacing of 10 cm. The tube was filled with a Kr/Xe/Br2/I2 working mixture, the total pressure being 0.5–2.0 kPa. The lamp’s emission spectrum consisted of a 206.2-nm iodine atomic line 0.1 nm wide at half-height and a continuum in a spectral region of 210–390 nm. The continuum resulted from overlapping of wide emission bands with peaks at 221 nm for XeBr(D-X), 253 nm for XeI(B-X), 282 nm for XeBr(B-X), 289 nm for Br 2 * , 342 nm for I 2 * , and 386 nm for IBr*. The total power of the ultraviolet emission was no more than 8–12 W, the power injected into the discharge being 10–100 W. The lamp lifetime in the gas-static mode was 300–400 h.

Emission of Ionic Molecules (KrXe)+ on Excitation by a Hard Ionizer

The molecular luminescence band appearing in the 445–510-nm region on excitation of a Kr-Xe mixture by the α particles of polonium 210 as well as by the products of nuclear reaction 3He(n,p)T has been investigated. Radiation at the transition of the heteronuclear ionic molecule (KrXe)+ has a high excitation efficiency and is observed in a temperature range from −100 to +600°C. The kinetics of the processes in the Kr-Xe mixture and the possibility of using radiation with λ ∼ 490 nm in radioactive light sources are considered.

Energy transfers in Kr–Xe mixtures following selective multiphotonic excitation of Kr(3P1). Temporal analysis in Kr–Xe mixtures

This work deals with energy transfer from the resonant state Kr(3P1) to xenon. A pulsed, brief and selective excitation of the molecular state Kr2[1u(3P1)] was achieved with a dye laser. An electrometer was used to select the appropriate excitation wavelength in order to prevent ionization. In mixtures, instead of the continuum of krypton, when a small amount of xenon was added, the first and second continua of xenon were observed, even though Kr(3P1) was initially excited, proving the efficiency of the energy transfer. From the temporal analysis in pure krypton, the three-body rate constants for Kr(3P1) and Kr(3P2) and the lifetime of the excimer Kr2[1u(3P1)] have been measured again. In the mixtures, we clearly showed the occurrence of energy transfer from Kr(3P1) to the Xe[5d(7/2)3] level, with a two-body collision rate constant of 6.8 × 105 Torr−1 s−1. A weak coupling could also intervene between these two states. The reverse collision rate constant ki was found to be about 2.9 × 103 Torr−1 s−1. The ternary heteronuclear collision rate constant of the Xe(3P2) state determined at 145 nm and 168 nm is in good agreement (38.7 Torr−2 s−1 and 36.7 Torr−2 s−1, respectively). Finally, a kinetic scheme of the main reaction processes is proposed.

Normal solution and transport coefficients to the Enskog–Landau kinetic equation for a two-component system of charged hard spheres: The Chapman–Enskog method

An Enskog–Landau kinetic equation for a many-component system of charged hard spheres is proposed. This equation is obtained from the Liouville equation with modified boundary conditions by the method of nonequilibrium statistical operator. On the basis of this equation the normal solution and transport coefficients such as bulk κ and shear η viscosities, thermal conductivity λ, mutual diffusion D αβ and thermal diffusion D T α are obtained for a binary mixture in first approximation using the Chapman–Enskog method. Numerical calculations of κ, η, D αβ and D T α for Ar–Kr, Ar–Xe, Kr–Xe mixtures with different concentrations of compounds have been evaluated for the cases of absence and presence of long-range Coulomb interactions. The results are compared with those obtained from other theories and experiment.

Spectroscopie et cinétique des gaz rares et leurs mélanges sous excitation multiphotonique

The purpose of this work is to bring out the analogous behaviour of krypton and xenon under multiphotonic excitation through three photons absorption. Excitation is acheived either on the 3 Pi state itself or in its neighbourhood. In this latter case the excitation consists of populating the dissociative l(3Pi) molecular state from ground state ditners. It also appears that, in our experimental conditions, excitation is mainly achieved through absorption of a VUV photon originating from the third harmonic of the incident laser beam. In the Kr-Xe mixture our excitation spectra bear both krypton and xenon components. The temporal analysis of krypton's emission filtered around 128 nm shows the existence of an energy transfer from the Kr ^i) state towards a 5d xenon state through binary collisions whose collision rate is 6,8105 Tore's1.

Lasing due to transitions in the Xe atom on excitation of a Kr—Xe mixture and of pure xenon with uranium fission fragments

An investigation was made of a high-pressure quasi-cw laser operating on the basis of the 5d—6p transitions in the Xe atom. The duration of the output radiation pulses was up to 7 ms. Competition between the lasing lines at λ = 2.63 and 2.8 μm was observed in a Kr—Xe mixture. The maximum output power was 150 W (corresponding to the efficiency of ~0.2%) and it was obtained for the 2.63 μm line in a mixture of the Kr : Xe = 50 : 1 composition when the pressure was 0.35 bar. The lasing threshold was reached when the thermal neutron flux was about 3×1012 cm-2 s-1. Lasing of pure Xe at pressures of 0.13–0.6 bar was observed at the 3.51 μm wavelength (in this case the maximum output radiation power was about 90 W).

On anomalous vacuum-UV emission by a cryogenic plasma in a krypton-xenon mixture

The anomalous emission (λ~146 nm) from a Kr–Xe mixture observed in a previous study is interpreted as emission in the course of optical collisions. A kinematic model is constructed which explains the dependence of the emission intensity on the composition and temperature of the gas mixture.

Collisional and radiative excitation transfers in Kr-Xe mixtures: Emissions from the Xe(3P1) resonant level and the Xe first continuum region.

Time-dependent and time-independent measurements of emissions from Xe in Kr-Xe mixtures are reported. Kr host gas pressure was varied from 100 to 900 Torr, and Xe impurities were varied from 1% to 10% of total Kr pressure. This work has shown that the Xe${(}^{3}$${\mathit{P}}_{1}$) resonant state is depopulated by collisions with both Xe and Kr ground-state atoms. In particular, a two-body quenching rate of 10 $^{4}\mathrm{P}_{\mathrm{Xe}}$+2100${\mathit{P}}_{\mathrm{Kr}}$ is reported. This two-body rate is assigned to represent a collisional transition to the Xe${(}^{3}$${\mathit{P}}_{2}$) metastable state. A three-body rate of 97${\mathit{P}}_{\mathrm{Xe}}$${\mathit{P}}_{\mathrm{Kr}}$+7${\mathit{P}}_{\mathrm{Kr}}^{2}$ was also found. The rate 7${\mathit{P}}_{\mathrm{Kr}}^{2}$ is assigned to represent the formation of (KrXe${)}^{\mathrm{*}}$ molecules, while the rate 97${\mathit{P}}_{\mathrm{Xe}}$${\mathit{P}}_{\mathrm{Kr}}$ represents either formation of ${\mathrm{Xe}}_{2}^{\mathrm{*}}$(${\mathrm{O}}_{\mathit{u}}^{+}$) or (XeKr${)}^{\mathrm{*}}$. Time-dependent measurements made in the Xe first continuum region at about 1500 \AA{} indicate that these emissions follow the Xe${(}^{3}$${\mathit{P}}_{1}$) state.

Commensurate-incommensurate transition of Kr-Xe mixtures on graphite.

We report high-resolution x-ray scattering measurements of the commensurate-incommensurate transition of Kr on graphite which has been preplated with 0.1 monolayer of Xe. The Xe raises transition pressure, and produces a 31% range of pressures over which composite lineshapes are observed. These results are discussed in terms of a solubility gap between commensurate and incommensurate phases.

Enhancement of the efficiency of a beam He laser by molecular additives

Addition of small amounts (1–3%) of molecular gases (N2,CO2) to high-density (p≈1–3 atm) Ar–Xe, He–Xe, and Kr–Xe mixtures pumped an electron beam (j ≈ 20–100 A/cm2) enhanced the energy of infrared laser radiation (λ ≈2.03 and 2.65 μ) by a factor of 10–15. The effect was attributed to an improvement in the recombination pumping as a result of reduction in the electron temperature.

Collisional and radiative excitation transfers in Kr-Xe mixtures: Quenching of Kr.

A detailed study of electronic energy transfers in Kr-Xe mixtures has been made using a 250-keV electron accelerator to excite Kr-Xe mixtures over a wide range of Kr-host-gas pressure and Xe-impurity concentrations. Kr pressure ranged from 25 to 900 Torr with Xe concentrations varying from 0.1% to 10% of Kr partial pressure. Emission spectra taken in the vacuum-ultraviolet (vuv) region indicate that energy is transferred efficiently from Kr to Xe, with radiation from the Xe${(}^{3}$${P}_{1}$) state becoming greatly enhanced as the Xe-impurity concentration is increased. Emission spectra from the vuv also show that the Xe${(}^{1}$${P}_{1}$) state is populated by absorption of photons emitted from the ${\mathrm{Kr}}_{2}$${\mathrm{}}^{\mathrm{*}}$ first continuum. Two-body quenching rates with Xe ground-state atoms have been found for the Kr${(}^{1}$${P}_{1}$) [${k}_{q}$(1165 \AA{})=1.2\ifmmode\times\else\texttimes\fi{}${10}^{5}$ ${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$/Torr] and for the Kr${(}^{3}$${P}_{1}$) [${k}_{q}$(1236 \AA{})=9.5\ifmmode\times\else\texttimes\fi{}${10}^{5}$ ${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$/Torr] resonance states. Time-resolved measurements have also been made on the ${\mathrm{Kr}}_{2}$${\mathrm{}}^{\mathrm{*}}$ first and second continua. These measurements show the Kr${(}^{3}$${P}_{1}$) state is the atomic precursor of the ${\mathrm{Kr}}_{2}$${\mathrm{}}^{\mathrm{*}}$ first continuum. The results obtained in the ${\mathrm{Kr}}_{2}$${\mathrm{}}^{\mathrm{*}}$ second continuum are rate limited by the decay of Kr${(}^{3}$${P}_{1}$) at large Xe-impurity concentrations.

Electron-beam-induced emission of KrXe +

The emission of KrXe + was studied in Kr-Xe mixtures excited by an intense beam of fast electrons using time-resolved spectroscopy techniques. Previous works are discussed and the discrepancies are explained by noting that the emission band around 490 nm is affected by atomic transitions. Time constants and rate constants for the formation of the molecular ion are given.

Kinetic study of the KrXe+heteronuclear ion emission

The emission spectra of KrXe mixtures were plotted at different total pressures and at xenon concentrations varying from 0.5 to 99%. A characteristic emission of the mixture was seen at 490 nm, it appeared as soon as possible as the mixture contained 0.5% xenon. The emission at 490 nm has a maximum intensity at a xenon concentration of 20%. The shape of the light pulses obtained for this transition is described by an exponential decay with a time constant corresponding to the formation of the radiative state. The KrXe+ ion involved is the IV1/2 state; the kinetic scheme given defines the role and the value of the various reaction rate constants.