Anomalous behavior of proton zero point motion in water confined in carbon nanotubes

The momentum distribution of the protons in ice Ih, ice VI, high density amorphous ice, and water in carbon nanotubes has been measured using deep inelastic neutron scattering. We find that at 5 K the kinetic energy of the protons is 35 meV less than that in ice Ih at the same temperature, and the high momentum tail of the distribution, characteristic of the molecular covalent bond, is not present. We observe a phase transition between 230 and 268 K to a phase that does resemble ice Ih. Although there is yet no model for water that explains the low temperature momentum distribution, our data reveal that the protons in the hydrogen bonds are coherently delocalized and that the low temperature phase is a qualitatively new phase of ice.     

Enhanced field ionization of water adsorbed on a carbon monoxide-covered, platinum field emitter tip

The influence of carbon monoxide, adsorbed on a platinum field emitter tip, on field ionization of adsorbed water was examined. Ramped field desorption (RFD) measurements of water ionization were performed at 108 K for water layer thicknesses up to 80 ML on a clean or CO-saturated tip surface. In RFD the applied field is ramped linearly in time until water ionization is detected, giving the onset field of ionization. Water ionization yields hydrated hydroxide ions and protons; the hydroxide ions remain within the water layer on the tip, while the hydrated protons are emitted into vacuum. At a low water coverage of 1.5 ML, the CO adlayer substantially reduced the onset field of ionization (that is, facilitated ionization) of water by 40%, from a value of 0.43 V/Å for water on clean Pt to 0.26 V/Å for water on CO-covered Pt. The extent of the reduction gradually diminished with thicker coverages of water and was absent at coverages of 20 ML or greater. The characteristic decay length of the field enhancement was 4.7 ± 1 ML. The results were analyzed with the charge exchange model of ionization kinetics and changes in dipole moments of water adsorbed without and with CO. The analysis reveals that a change in water structure (dipole moment) caused by CO is an important contributor in field enhancement and that the dipole moment for hydrated hydroxide ion in an ice-like layer must be greater than that for bulk ice-like water. The significance of these results with respect to electrochemical oxidation of CO is discussed.     

Field extraction of ions from liquid solutions with the use of polymer track membranes

The general principles of the electric field assisted ion evaporation in the membrane ion source are considered. In the ion source, the liquid sample under investigation is placed in narrow channels of a polymer track membrane, which separates the liquid sample at atmospheric pressure from the vacuum chamber. Stability of the liquid at strong electric fields is provided by a choice of the diameters of channels and the liquid–polymer contact angle. The electric charge on the vacuum–polymer interface is of great importance for creation of the strong electric field near the liquid–vacuum interface. Such a conclusion is made from the computations of the electric field in the framework of the model developed. The mechanism of the electric field assisted evaporation of ions is discussed to explain the observed mass spectra for the ions extracted from liquid.     

Measurement of the charge state distribution of field evaporated ions originating from alloys

The charge state distribution of field evaporated ions from the pure metals Mo, W, Au, Pt and from alloys of these elements has been determined as a function of the electric field strength. The change of the mean charge of these elements when desorbed from an alloy with a different evaporation field can be explained by the model of post ionization. The general validity of this model has also been tested for the change of the mean charge of iridium ions evaporated in the presence of adsorbed hydrogen.     

High-temperature field evaporation and its connection with surface ionization

High-temperature field evaporation of metals and alloys and its connection with surface ionization are considered. The main parameters of the evaporation process (dependence of the evaporation rate on the emitter temperature and on the electric field at the emitter surface, the charge of the ions being evaporated and its temperature dependence, kinetic parameters of the evaporation process, as well as the state of the emitter surface under simultaneous action of high fields and temperatures) are analyzed. The similarity and the difference between field evaporation at high temperatures and surface ionization in a strong electric field are determined.     

Three-dimensional simulations of ion acceleration from a foil irradiated by a short-pulse laser

Using 3D particle-in-cell simulations we study ion acceleration from a foil irradiated by a laser pulse at 10(19) W/cm(2) intensity. At the front side, the laser ponderomotive force pushes electrons inwards, thus creating the electric field by charge separation, which drags the ions. At the back side of the foil, the ions are accelerated by space charge of the hot electrons exiting into vacuum, as suggested by Hatchett et al. [Phys. Plasmas 7, 2076 (2000)]. The transport of hot electrons through the overdense plasma and their exit into vacuum are strongly affected by self-generated magnetic fields. The fast ions emerge from the rear surface in cones similar to those detected by Clark et al. [Phys. Rev. Lett. 84, 670 (2000)].     

Screening of an Electric Field in Water

JETP Letters - The screening of an electric field in water has been studied taking into account correlations between protons, which are described by the ice rules. It is shown that the problem has...     

A search for fractional electric charge in sea water

The magnetic levitation technique has been used to test for fractional electric charge in sea water, using steel balls coated with sea water residue by evaporation. The objective was to reach concentration levels below 1 g^?1 which might result from cosmic ray interactions. Four stages of increasing sensitivity are reported: (1) residue from direct evaporation of unprocessed sea water, (2) residue from sea water samples enriched by ion exchangen, (3) residue reduced by high temperature evaporation, and (4) hypothetical enrichment by dilution and separation of soluble residue. Stages 1–3 are based on the generally accepted preferential retention of fractional charge during evaporation, but stage 4 limits are subject to uncertainties in the enrichment process. No evidence for fractional charge was found in a total of about 130 samples tested in these four stages. Samples containing positive and negative ions were tested separately, and concentration limits are reported for each of the stages. Levels in the region 0.01–0.1g^?1 were reached in stage 3, and 0.001 g^?1 in stage 4.     

The influence of dielectric surface charge distribution upon thepartial discharge behavior in short air gaps

A two-dimensional breakdown model based upon the continuity equations for electrons and ions and the Poisson equation is employed to examine the influence of surface charges upon the partial discharge behavior of a short metallic-dielectric plane-parallel electrode gap of 0.05 cm in an air-like mixture at atmospheric pressure. The form of charge distribution at the dielectric electrode surface is found to significantly affect a number of important discharge parameters, such as the uniformity of the electric field, the charge density and its radial distribution within the gap, as well as the discharge propagation time     

运行时间对油水真空分离的影响

为获取运行时间对油水分离动态特性的影响,考虑油水汽三相流、水滴蒸发相变等因素,建立滤油机的油水分离流场的数学物理模型及水滴运动蒸发的相变方程;分析运行时间对油水分离过程中油水汽三相体积分数分布以及轴向脱水率的影响,表明不同运行时间油水汽三相流的动态特性,运行时间显著影响油水分离的脱水效率,为研究滤油机的油水分离机理奠定基础.     

Measurement of the charge state distribution of field evaporated ions: Evidence for post-ionization

Charge state distributions of field evaporated Si, Ni, Mo, Rh, W, Re, Ir and Pt ions have been measured as a function of electric field strength using the pulsed laser atom-probe. The results are compared to previously published theoretical calculations based on the post-ionization model of field evaporation. The agreement between theory and experiment is sufficient to establish the general validity of the post-ionization model. Measurements of the charge state distributions as a function of evaporation rate at constant temperature (increasing field) and constant field (increasing temperature) are also presented for W, Mo and Si. The observation that the fractional abundances of different charge states for the same material do not change with changing temperature indicates that the activation energies of desorption are the same for the different charge states and provides further support for the post-ionization model. The anomalous field evaporation behavior observed at high temperatures (e.g., desorption from localized areas on the surface and the occurrence of ionic clusters) is also discussed.     

Formation and dispersion of an electrolyte film on an ice electrode melting as a result of Joule heat evolution

The thickness of a liquid film (≈3.6 μm) forming on an ice electrode is determined by solving the Stefan problem. The electrode melts as a result of Joule heat evolution when the current passes through it. The temperature distributions in the film and ice substrate are found. The radius of curvature of emitting asperities formed as a result of film instability against the surface charge is found to be ≈40 nm. This value provides the intense field evaporation of individual ions and ionic clusters from the top of the asperities at a potential difference of ≈100 V.     

Autowave Regimes of Thundercloud Electrification

We consider the evolution of the electric field and charge in a one-dimensional electrohydrodynamic (EHD) distributed-parameter system which serves as a simple model of a thundercloud. A diffusion equation for the electric field is proposed which, under reasonable assumptions on the nonlinear dependence of the dissipation current on the electric field (caused by the corona effect around aerosol particles in strong fields), has autowave solutions describing the dynamics of spatially separated electric-charge regions in the thundercloud. The nonlinear set of equations describing the electric-field dynamics in an ensemble of colliding aerosol particles and light ions is reduced to a rather simple basic model which admits solutions in the form of traveling fronts and traveling pulses. We find the asymptotic values of the velocity and thickness of the space-charge front, which are determined by the diffusion and the separation and conductivity currents. Using these values, we estimate the electrostatic-energy growth rate in a thunderstorm cell at the stage of its intensive electrification. A possibility is shown of the formation of a traveling pulse of field and conductivity in such an EHD system with allowance for inductive and noninductive mechanisms of aerosol-particle charging.     

Field evaporation of doubly charged ions from a polar liquid

The effect of charge on field evaporation of ions from polar liquids is considered. Using the electromembrane ion source, we performed mass-spectral analysis of field evaporation of ions from the solution of sodium sulfate in a water-glycerol mixture. The composition of doubly charged cluster ions in the field evaporation from glycerol is determined. The rates of the field evaporation of doubly charged ions and singly charged ions are compared. It is shown that the ion charge as well as its localization considerably influences the efficiency of field evaporation of ions from polar liquids.     

磁暴主相期间环电流分布特性模拟研究

磁暴主相期间对流电场驱动等离子体片中的能量粒子经历E×B漂移，被地磁场俘获形成环电流，在此理论基础上充分考虑电荷交换造成的环电流损失与离子沉降的影响，改善并验证了磁暴主相期间环电流离子分布模式.模拟了不同强度磁暴主相期间磁层环电流离子的分布特征，研究了部分环电流离子对对流电场的响应.结果表明：不对称的环电流是磁暴主相期间环电流的重要组成部分，其分布特性表现为晨昏不对称和日夜不对称以及离子投掷角分布的各向异性等.对流电场与能量离子通量强度和分布范围之间正相关.模拟结果与观测有很好的一致性，证明了模型的可行性 关键词： 部分(不对称)环电流 磁暴主相 离子通量分布 对流电场     

Field evaporation of impurity ions from a liquid gallium ion source

The charge states of ions emitted from a gallium liquid metal field ion (LMI) source contaminated with tin and copper have been measured. The results for tin show that the proportion of Sn²⁺ to Sn⁺ is much larger than is found for a LMI source of pure tin. A model in which Sn²⁺ is assumed to be produced by post-ionization of Sn⁺ is used to set an upper limit to the electric field at the point of emission. Its value is approximately equal to that predicted by field evaporation theory for a pure gallium source. Consequently the charge states of emitted impurity ions are determined by field strengths imposed by the main component.     

Composition of the ion current during field evaporation of some binary and ternary compounds at different temperatures

Experiments on the field evaporation of emitters made of Mo-Re, Ir-Ce, and W-Re binary alloys and Hf-Mo-Re ternary compound are described. It is shown that, depending on emitter preprocessing conditions (high-temperature heating in a high electric field), either atomic ions of almost all components of the alloy with different charge types are emitted simultaneously or ions of only one component of the compound are obtained. Field emitters made of alloys or multicomponent compounds may form a basis for sources of ions differing in mass and composition with the emitter composition remaining the same. Moreover, alloys and multicomponent compounds are promising for sources of ions of such materials of which field emitters are difficult, if at all possible, to prepare.     

A new approach to the use of EMMRS: Ionic Mobility MR Spectroscopy (IMMRS)

A new approach to the use of the previously proposed method called Electrical Mobility Magnetic Resonance Spectroscopy (EMMRS) has been worked out. It consists in obtaining mobility distribution, lifetimes, and activation energy of charge carriers by introducing into the medium a longitudinal elastic wave perpendicular to the electric field which causes displacement of charges (electrons, protons, ions, free radicals, and molecules related with charge carriers) present in the biological environment or inanimate matter. Such a method allows for determination of these quantities within small areas, thus offering possibilities for their imaging. We therefore suggest to call it Ionic Mobility MR Spectroscopy (IMMRS).     

非共沸混合工质自复叠热泵循环试验研究

单级压缩式热泵冷凝温度与蒸发温度之差一般为40~50℃,非共沸混合工质自复叠循环具有工作温差大的优点,将其应用于热泵循环,则可产生较大的供热温差。该文通过搭建一个空气源自复叠热泵实验台,利用NIST公司的制冷剂物性数据库Refprop7,绘制出了混合工质的温度-浓度图。经过实验,分析了自复叠热泵循环工作温差的影响因素,得出了自复叠热泵气液分离器简单分离对增大工作温差的作用有限,增加工质的相对挥发度也不能显著改善热泵的运行性能等结论。并进一步得出了增设分凝设施可显著增大工作温差的结论。     

Proton ordering in ice at an ice-metal interface

The structure of the proton sublattice of ice at an ice-metal interface is analyzed by solving the Ginzburg-Landau equation for an order parameter describing the proton ordering under an appropriate boundary condition [1, 2]. When the interaction between protons and the substrate is weak, the ice rules that govern proton order are weaker at the interface as compared to bulk ice, but to a lesser extent than at the free ice surface. In the case of strong proton-substrate interaction (clean interface and/or high conductivity of the substrate), the ice rules are stronger at the interface as compared to bulk ice, which corresponds to a more ordered proton sublattice. The latter case corresponds to a lower concentration of defects in the proton sublattice, which determine important properties of ice, such as adhesion, electrical conductivity, plasticity, and electric field distribution near the interface. A qualitative correlation is described between electrical properties of the substrate and mechanical properties of the interface, including adhesion and friction.