Lithium Evaporation Research Articles

Sympathetic cooling with two atomic species in an optical trap.

We simultaneously trap ultracold lithium and cesium atoms in an optical dipole trap formed by the focus of a CO2 laser and study the exchange of thermal energy between the gases. The optically cooled cesium gas efficiently decreases the temperature of the lithium gas through sympathetic cooling. Equilibrium temperatures down to 25 microK have been reached. The measured cross section for thermalizing 133Cs-7Li collisions is 8 x 10(-12) cm(2), for both species unpolarized in their lowest hyperfine ground state. Besides thermalization, we observe evaporation of lithium purely through elastic cesium-lithium collisions (sympathetic evaporation).

Study of cobalt-doped lithium–nickel oxides as cathodes for MCFC

Cobalt substituted lithium–nickel oxides were synthesized by a solid-state reaction procedure using lithium nitrate, nickel hydroxide and cobalt oxalate precursor and were characterized as cathodes for molten carbonate fuel cell (MCFC). LiNi 0.8Co 0.2O 2 cathodes were prepared using non-aqueous tape casting technique followed by sintering in air. The X-ray diffraction (XRD) analysis of sintered LiNi 1− x Co x O 2 indicated that lithium evaporation occurs during heating. The lithium loss decreases with an increase of the cobalt content in the mixed oxides. The stability studies showed that dissolution of nickel into the molten carbonate melt is smaller in the case of LiNi 1− x Co x O 2 cathodes compared to the dissolution values reported in the literature for state-of-the-art NiO. Pore volume analysis of the sintered electrode indicated a mean pore size of 3 μm and a porosity of 40%. A current density of 160 mA/cm 2 was observed when LiNi 0.8Co 0.2O 2 cathodes were polarized at 140 mV. The electrochemical impedance spectroscopy (EIS) studies done on LiNi 0.8Co 0.2O 2 cathodes under different gas conditions indicated that the rate of the cathodic discharge reaction depends on the O 2 and CO 2 partial pressures.

Lithium loss from lithium cobalt oxide: hexagonal Li0.5Co0.5O to cubic Li0.065Co0.935O phase transition

Lithium loss from LiCoO2 following isochronal thermal treatment for 5 h in the temperature range 850–1300°C was determined by thermogravimetric (TGA) and diffractometric (XRD) measurements. Lithium vaporization starts from 900°C, and following thermal treatment at 1300°C 85% of lithium was lost. At 1050°C a change in the mechanism of lithium and oxygen evaporation was observed. Initially, following lithium loss, LiyCo2−yO2 (solid solution of CoO in LiCoO2) was formed. An activation energy of 305 kJ mol−1, not too far from the heat of reaction from Li2O to Li2O2 vapour, was obtained. Phase transition to cubic Li0.065Co0.935O structure occurred starting from thermal treatment at 1050°C. Both hexagonal and cubic lithium cobalt oxide structures were subjected to phase transition to get LiCoO2 and Co3O4 during cooling, but the cubic phase was stabilized against phase transition with increasing temperature.

Neutronics features of a high power density first wall/blanket with lithium evaporation cooling

Two-dimensional neutronics analysis has been performed for the Evaporation of Lithium and Vapor Extraction (EVOLVE) FW/blanket concept. The concept utilizes a refractory alloy (W-5Re) structure. The overall tritium breeding ratio is 1.37 at a lithium enrichment of 40% 6Li. The amount of nuclear heat deposited in the different regions was determined. About 76% of the total thermal energy is carried by the Li vapor to the heat exchanger. Since this heat is extracted at a temperature of 1200°C, a power conversion efficiency >60% can be achieved. No significant poloidal peaking is observed in the nuclear heating and damage profiles. Shielding requirements for the vacuum vessel and magnet are satisfied.

Experimental study of lithium target under high power load

This paper presents experimental research on simulation of a free liquid lithium surface under high heat flux impact for divertor application. Capillary porous structure (CPS) was taken to form the free liquid metal surface imitating divertor target plate. Experiments were performed in the SPRUT-4 linear plasma device with electron beam as power source. Lithium-filled targets were investigated at 1–50 MW/ m 2 heat loads in steady state. Lithium evaporation, energy and mass balance, surface temperature, vapor ionization, lithium plasma parameters and radiation were studied. Detailed thermal analysis was made to study heat flows in the target and their correspondence with experimental observations. Durable operation of the setup was possible in the range 1–20 MW/ m 2 without damage of the structure. The relevance of the experimental performance to divertor condition is analyzed.

Structural Properties and Thermal Behavior of Li2CO3–BaCO3 System by DTA, TG and XRD Measurements

The binary system Li2CO3–BaCO3 was studied by means of differential thermal analysis (DTA), thermogravimetry (TG) and X-ray phase analysis. The composition of carbonate and CO2 partial pressure influence on the thermal behavior of carbonate were examined. It was shown that lithium carbonate does not form the substitutional solid solution with barium carbonate, however the possible formation of diluted interstitial solid solutions is discussed. Above the melting temperature the mass loss is observed on TG curves. This loss is the result of both decomposition of lithium carbonate and evaporation of lithium in Li2CO3–BaCO3 system. Increase of CO2 concentration in surrounding gas atmosphere leads to slower decomposition of lithium carbonate and to increase the melting point.

An Investigation of Evaporation of Lithium

The Knudsen effusion method with mass-spectrometric analysis of evaporation products is used to determine the composition and pressure of saturated vapor over liquid lithium in the temperature range from 627 to 893 K. The Li(l) = Li(g), 2Li(l) = Li2(g), and Li2(g) = 2Li(g) reactions are investigated. The measured values of partial pressure for Li and Li2are used to calculate the values of enthalpy for these reactions at 0 K by the second, ΔrH00(II), and third, ΔrH00(III), laws of thermodynamics: ΔrH00(II) = 157.9 ± 0.5, 214.2 ± 0.6, and 101.4 ± 1.1 kJ/mol, and ΔrH00(III) = 157.5 ± 0.3, 213.9 ± 0.3, and 101.1 ± 0.6 kJ/mol, respectively.

ITER structural design criteria and their extension to advanced reactor blankets

Applications of the recent ITER structural design criteria (ISDC) are illustrated by two components. First, the low-temperature-design rules are applied to copper alloys that are particularly prone to irradiation embrittlement at relatively low fluences at certain temperatures. Allowable stresses are derived and the impact of the embrittlement on allowable surface heat flux of a simple first-wall/limiter design is demonstrated. Next, the high-temperature-design rules of ISDC are applied to evaporation of lithium and vapor extraction (EVOLVE), a blanket design concept currently being investigated under the US Advanced Power Extraction (APEX) program. A single tungsten first-wall tube is considered for thermal and stress analyses by finite-element method.

The use of liquid metals in porous materials for divertor applications

Features of using capillary porous materials (stainless steel, tungsten, graphite) cooled by liquid lithium for divertor module of thermonuclear fusion reactor have been considered. Temperature distribution in divertor plate under the power density of 10 MW/m 2 was calculated for steady state and pulsed heat influences. The surface temperature as a function of power density and dependence of lithium evaporation yield on temperature was evaluated. Thickness of cover lithium layer with safe porous material against direct pulse heat influence type of plasma disruption (power density in the range of (1–5)10 3 MW/m 2) was estimated. Concerning the problem under consideration, features of hydrodynamic and capillary effects as well as chemical interaction between lithium and investigated materials have been discussed.

In situ silicon and lithium coating and its removal in the HL-1M tokamak

Siliconization and lithium coating of the wall in the HL-1M tokamak were performed by means of DC glow discharges with a mixture of SiH 4 and He and lithium evaporation in a He glow discharge, respectively. With the wall conditioning, impurities and radiation power losses are generally lower than those with boronization, and strong wall pumping and low hydrogen recycling occur in these tokamak discharges. The excellent wall conditions lead to great progresses in such experiments as the multi-shot pellet injection, LHCD and long pulse discharges. Removal of these coatings by DC glow discharges with H 2 and He was demonstrated.

Gas and hydrogen ion gettering properties of lithium

The gettering properties of lithium films for O 2, CO 2 and H 2O were examined in a vacuum system with a heater for lithium evaporation. The absorbed amounts of O 2, CO 2 and H 2O observed were in the ratio, O 2/Li=0.2, CO 2/Li=0.01 and H 2O/Li=0.12. The gettering action for H 2O was saturated at a relatively low lithium evaporation amount. The hydrogen uptake of a lithium oxide film was also investigated by using an ion irradiation apparatus with a thermal desorption spectroscopy. The ratio of retained hydrogen was H/Li ≃ 0.7, which was roughly the same as in the case of a fresh lithium film. The helium ion irradiation reduced the hydrogen retention of the lithium oxide film. The retained amount was 50% of that before the helium ion irradiation.

Loss of metallicity in metal rich lithium oxide clusters

Mixed lithium-lithium oxide aggregates are experimentally obtained from unimolecular evaporative cascades starting at metal rich Li p + (Li2O)n species and ending with the stoichiometric limit Li+(Li2O)n, for several sizes of the oxide part (Li2O)n with 0 ≤ n ≤ 8. The results show evidence of the vanishing of the properties of the quantum metallic droplet i.e. shell closing and odd-even alternation, portrayed in the dissociation energy, with increasing size of the oxide component. The competition between monomer and dimer lithium evaporation from the heated metal rich Li p + (Li2O)n species points out the influence of the perturbation induced by the oxide component on the mixed metal oxide clusters.

Mixed valent niobium nitrides and oxynitrides resulting from ammonolysis of alkaline niobates

Nitridation of alkaline niobates MNbO 3 and MNb 3O 8 (M = Li, Na, K) in flowing ammonia leads to different reaction products depending on the temperature and the considered niobate. Two series of mixed valent NaCl-type oxynitrides are formed in the LiNbON system. A complete nitrogen/oxygen substitution can be obtained since the ternary oxide LiNb 3O 8 is transformed, without lithium evaporation, into a ternary nitride LiNb 3N 4 which has a filled up MoS 2-type structure. Reaction of sodium or potassium niobates with NH 3 results in a total evaporation of sodium or potassium and formation of the binary nitride Nb 4N 5 closely related to the NaCl structure.

Impurity production and transport processes in divertor regions

2D modelling of the ITER divertor with a lithium target are presented as the first step in the validation of a new divertor concept, based on the capillary structure applied for the cooling of the divertor plates by the evaporation of lithium. The lithium radiative divertor scenario has been examined for the ITER using the DDIC95 code. This code has been specially produced to simulate the behavior of the main plasma and that of impurities, at their arbitrary densities in a real divertor geometry. The self-consistent simulation of a background plasma, neutral gas and impurities is a specific feature of this code. First calculations have shown that the thermal loads on the divertor plates are reduced to 1 MW/m 2. The main power entering the divertor is radiated on the baffles in the divertor. The longitudinal and radial distributions of lithium neutral and ion density are presented in this paper. The lithium flux through the magnetic line near the separatrix and Z eff in the main plasma are estimated. On the basis of the 1D code the fusion plasma parameters inside the separatrix and the values of lithium flow through the separatrix at which the self-sustaining D-T reaction takes place have been calculated.

Study on the WO 3 dry lithiation for all-solid-state electrochromic devices

In this report, a simple WO 3 dry lithiation is proposed for fabrication of all-solid-state electrochromic devices and characterized completely by X-ray photoelectron spectroscopy and electrochemical method. Lithiation is carried out by electron-beam evaporation of metal lithium, and the lithiated films have different components and electrochromic properties with different lithiation degrees. It is found that if Li/W ratio is less than 0.25, tungsten bronze Li x W0 3 is formed and the lithiated by wet method. Finally, a lithium-based all-solid-state electrochromic device with proper lithiation degree is fabricated using this dry method.

Electronic structure and electron emission of lithium-containing amorphous hydrogenated carbon films

Amorphous hydrogenated carbon films were prepared by ion beam deposition. The degree of sp3 coordination and the density of the films were determined from ultraviolet photoelectron valence band spectra and electron energy loss spectra. The films prepared can be described as highly sp3 coordinated (about 80%) and of relatively high density (about 2.3 g/cm3). An indication of a negative electron affinity is found in the valence band spectra. In an attempt to lower the work function, lithium-containing a-C:H films were deposited by lithium evaporation from dispensers during deposition of the a-C:H films. Photoelectron spectra of these films reveal parallel shifts of the core levels and valence band to higher binding energies with respect to the spectra of pure amorphous hydrogenated carbon. These shifts can be attributed to a shift of the Fermi level due to a charge transfer from the lithium to the carbon matrix. From the onset of the valence band spectra at low kinetic energy and from total photoyield spectra the work function of the samples was determined independently. A reduction of the work function from 3.4 eV in pure a-C:H to 2.45 eV in samples containing 35 at. % lithium is observed.

Wall conditioning with lithium evaporation

Thin lithium layers are deposited on metal or graphite walls by evaporation in vacuum. Clean lithium surfaces have wide chemical activities on such gases as O 2, CO and CH 4. In particular, a strong gettering effect on oxygen is observed; the maximum number of O atoms gettered by the lithium layer is about one half the total number of Li atoms deposited on the wall, thus suggesting the formation of Li 2O. On the other hand, H 2 gas hardly reacts with the lithium surface which, however, displays a large pumping effect in a hydrogen glow discharge. The maximum number of H atoms pumped by the lithium layer below 180°C is approximately equal to the number of Li atoms in the vessel, probably due to the formation of LiH. Helium glow conditioning of the used lithium layer allows the partial recovery of lithium from losses to hydrogen pumping or oxygen gettering. This lithium evaporation method has been applied to JIPP T-IIU. 100–250 mg of lithium was deposited onto a limited vessel area of ∼ 1 m 2. The lithium coating leads to 20–50% reduction in oxygen and carbon impurities with less hydrogen recycling in ohmic and NBI discharges.

Analysis of beam-on-target interaction in a neutron-source test facility

The need is urgent for a high-flux, high-energy neutron test facility to evaluate the performance of fusion reactor materials. An accelerator-based deuterium-lithium source is generally considered the most reasonable approach to a high-flux neutron source in the near future. The idea is to bombard a high-energy (20–40 MeV) deuteron beam into a lithium jet target to produce high-energy neutrons in order to simulate a fusion reactor environment via the Li (d, n) nuclear stripping reaction. Deposition of the high-energy deuteron beam and the subsequent response of the lithium jet are modeled and evaluated in detail. To assess the feasibility of this concept, the analysis is done parametrically for various deuteron beam energies, beam currents, and jet velocities. A main requirement for a successful operation is to keep the free jet surface at a minimum temperature to reduce surface evaporation of lithium into the vacuum system. The effects of neutron-generated heating and irradiation on the jet-supporting back plate are also evaluated. The back plate must maintain a reasonable lifetime during system operation.

Simultaneous analysis of Li and B in amorphous thin film glasses using ERDA

Starting from Li2O-B2O3-SiO2 melts of definite composition thin amorphous films were prepared on glass substrates by physical vapor deposition. The conventional ERDA proved helpful to analyse the lithium to boron concentration ratios in the layers of any thickness and in the compact initial glass material. Selective lithium evaporation is observed due to the dominance of the LiBO2 partial pressure above the melt.

Evaporation of lead and lithium from molten Pb17Li — Transport of aerosols

Evaporation of Pb and Li from molten Pb17Li was investigated between 350 and 800°C in vacuum, argon and helium covergas. Results were also obtained from other experimental facilities. Similarities were found to observations from sodium cooled reactors. The results show that Pb and Li evaporate independent on each other. The two elements show different behavior along the transport pathway. Deposits of the evaporated metals contained between 0.2 and 98 at% Li. As in the reactor RAPSODIE for sodium, evaporation rates for lithium were smaller in helium than in argon, however evaporation rates of lead were the same in both gases. No aerosol problems will exists with normal blanket operation. Under experimental conditions, aerosol concentrations were in the range of 10 −9 to 10 −6 g/m 3. Aerosols can easily be trapped with sintered metal filters.