Charged Gas Research Articles

極低温移動管質量分析装置

The drift tube method, which is known as one of the powerful techniques for low energy atomic collision experiments, is explained with description on the history of this method. A new selected ion drift tube mass spectrometer, which has been developed for ion swarm experiments at very low temperature, is presented. Gas temperature of 2 K in the drift tube as the lowest one for this apparatus is achieved by liquid helium cooling. Details of this set-up are described, and several technical points for the low temperature experiment, which are concerned in the development of this apparatus, are discussed: analysis of the heat flow rates into the drift tube, thermal contraction of metallic parts, temperature measurements of gas and solid surfaces, and gas pressure correction with respect to the thermal transpiration effect because of large temperature difference between the drift tube and the capacitance manometer. Mass spectra with the injection of doubly charged rare gas ions, Ar2+ and Kr2+, into helium gas are shown as examples of experimental results with this apparatus. Charge transfer, ion-molecule and atomic association reactions take place in the drift tube. Structure of large helium cluster ions K2+Hen (n≤40), which have been observed to have magic numbers n=12 and n=32, is discussed.

Use of metastable, dissociated and charged gas species in synthesis: a low pressure analogue of the high pressure technique

Oxidation of silver using microwave-induced oxygen plasma and oxygen-ozone gas mixture was studied as a function of temperature and partial pressure. The oxide Ag2O was formed at temperatures well above its normal decomposition temperature in oxygen plasma at a pressure of 5 Pa. The higher oxide AgO1−x was formed in O2+O3 gas mixtures at lower temperatures. The oxygen chemical potentials for the oxidation of Ag to Ag2O, Ag2O to AgO1−x and AgO to Ag2O3 were evaluated from thermodynamic data and compared with the experimental results to obtain information on the chemical potential of oxygen in microwave plasma and gases containing ozone. The oxygen potential of the gas phase in microwave plasma operating at a pressure of 5 Pa was found to be in excess of 36 kJ/mol at 750 K. This is equivalent to a pressure of diatomic oxygen gas greater than 3 × 107 Pa. In the O2+O3 mixture at ambient pressure containing 5 mole percent O3, the oxygen potential is ∼112 kJ/mol at 465 K. The equivalent pressure of diatomic oxygen is ∼4 × 1017 Pa. Thus, metastable species such as O3 or charged species such as O− present in plasma can be used as a powerful reagent for the syntheses of metastable oxides. Similar techniques can be used for other metastable inorganic solids such as nitrides for functional applications.

Novel Rare Gas Ions BXe+, BKr+, and BAr+ Formed in a Halogen/Rare Gas Exchange Reaction

Singly charged rare gas borynium ions were prepared for the first time by making use of mass-selected ion/molecule reactions in a triple-quadrupole mass spectrometer. Halogen for rare-gas exchange reactions leading to the formation of the novel species BAr+, BKr+, and BXe+ were carried out by allowing the radical cation BBr+• to react with neutral rare gas atoms in the second quadrupole under conditions typically used for collision-induced dissociation (CID) in tandem mass spectrometry experiments. The ions formed contain the bonds B−Ar, B−Kr, and B−Xe, the lengths of which were calculated at the B3-LYP/LANL2DZ level of theory to be 2.590, 2.635, and 2.713 A, respectively. Natural bond orbital (NBO) population analysis revealed that the bond order increases with increasing size of the rare gas atom: Ar < Kr < Xe. The reactions leading to the formation of the singly charged boron cations of Ar, Kr, and Xe are endothermic by 50.1, 45.8, and 38.7 kcal/mol, respectively. The energy required to drive these re...

On the physics of Landau damping

The quantitative explanation of neutral sound absorption at extremely low pressures within the framework of Landau’s theory (Sukhorukov and Stubbe [Phys. Plasmas 2, 4059 (1995)]) has revived the question about the physical nature of Landau damping. In the present paper it is shown in several ways that the physical mechanism behind linear Landau damping does not depend on the presence of charges. It is shown, in particular, that in the collisionless limit the damping rate of a given spatial and temporal structure is entirely determined by its spectrum, independent of whether the particles of the system are charged or uncharged. The role of charges lies in their influence on the shape of the spectrum. The conventional picture of Landau damping, involving the resonant conversion of wave energy into particle kinetic energy by electrostatic interaction, is critically investigated, and the shortcomings of this picture are unveiled. Landau damping is then described as thermal spread, which applies to both charged and uncharged gases. A correct estimate of the damping rate, based on this picture, is given in the low-damping limit.

On transfer of motion in a system of two-dimensional superfluid Bose-gases separated by a thin layer

The effect of transfer of motion between superfluid 2D Bose gases separated by a thin layer is predicted on the basis of microscopic calculations. It is shown that the effect exists at nonzero temperatures as well as at T=0 only for a closed secondary circuits. The dependence of the drag current on temperature and thickness of the layer is determined for charged Bose gases. An experiment is proposed for measuring the predicted effect.

The Non-relativistic Charged Bose Gas in a Magnetic Field II. Quantum Properties

The formalism presented in a paper by V. Kowalenko and N. E. Frankel (1994, Ann. Phys. (N.Y.)234, 316) is used here to evaluate the various response functions of the charged Bose gas in an external magnetic field at T=0K, where quantum effects dominate. By introducing recently developed asymptotic expansions for the particular Kummer function that appears in these response functions, analytic expressions for the dispersion relations of longitudinal and transverse modes are obtained in both the weak and strong field limits, thereby overcoming the problems caused by the system's anisotropy. As expected, taking the B→0 limit of the weak magnetic field results yields the already known field-free results while the results obtained for strong magnetic fields are heavily influenced by the cyclotron motion of the particles. Bernstein modes or resonances for the system are also evaluated in the strong magnetic field limit. In addition, the screening potentials for a test-particle immersed in the system are evaluated in both magnetic field limits. As the field is turned off, the screening potential for a weak magnetic field reduces to the field-free result, which consists of a Debye-like potential multiplied by an oscillatory term. This potential becomes isotropic for large distances away from the test-particle. In the strong field limit the screening potential is composed of a Debye-like potential multiplied by powers of the displacement in the direction of the magnetic field, but does not contain the oscillatory behaviour of its weak field counterpart. To demonstrate the versatility and power of the asymptotic expansions presented here, they are applied to the classical Maxwellian magnetoplasma, whereupon the dispersion relations for the longitudinal oscillations are obtained in both magnetic field limits. New expressions for Bernstein modes differing from those originally found by Bernstein are also derived.

A fourier transform ion cyclotron resonance study of two- and one-electron capture reactions between doubly charged rare gas ions and rare gas atoms

A Fourier transform ion cyclotron resonance (FTICR) mass spectrometer has been used to study near thermal collision energy symmetric charge transfer reactions. The systems Xe n+ /Xe, Kr n+ /Kr and Ar n+ /Ar have been measured at ambient temperature, where n = 1, 2. In the interactions between doubly charged rare gas ions and their corresponding neutral gas atoms the double electron capture (DEC) has been observed to be more efficient than the single electron capture (SEC). From the measured overall rate coefficient of 3.4 × 10 −10 cm 3 s −1 and the branching ratio of 1.1 between the DEC reaction and the SEC reaction the rate coefficients for double and single electron transfer from Xe to Xe 2+ have been calculated to be 1.8 × 10 −10 cm 3 s −1 and of 1.6 × 10 −10 cm 3 s −1. In the experiments with doubly charged krypton and doubly charged argon ions in their parent gases the symmetric double charge transfer is observed to be even more favored in comparison with the Xe 2+/Xe system at near thermal collision energies.

X-ray Measurements of Charge Transfer Reactions Involving Cold, Very Highly Charged Ions

The magnetic trapping mode of the Livermore high-energy Electron Beam Ion Trap is exploited to study charge transfer reactions between cold (few eV/amu) highly charged ions and gases. By selectively puffing neutral gases and monitoring the x-ray emission, state-selective measurements of the charge transfer reaction channels are possible. The observed K-shell x-ray spectra show prominent emission from high-n levels decaying to the n = 1 ground level, which is enabled by electron capture into states with low orbital angular momentum. A comparison with modeling calculations, therefore, allows a determination of the range of principal and angular momentum quantum numbers involved in the reaction.

A steady‐state system in non‐equilibrium thermodynamics including thermal and electrical effects

The steady-state equations for a charged gas or fluid consisting of several components, exposed to an electric field, are considered. These equations form a system of strongly coupled, quasilinear elliptic equations which in some situations can be derived from the Boltzmann equation. The model uses the duality between the thermodynamic fluxes and the thermodynamic forces. Physically motivated mixed Dirichlet Neumann boundary conditions are prescribed. The existence of generalized solutions is proven. The key of the proof is a transformation of the problem by using the entropic variables, or electro-chemical potentials, which symmetrize the equations. The uniqueness of weak solutions is shown under the assumption that the boundary data are not far from the thermal equilibrium. A general uniqueness result cannot he expected for physical reasons. © 1998 B. G. Teubner Stuttgart--John Wiley & Sons, Ltd.

One-loop effective potential for a fixed charged self-interacting bosonic model at finite temperature with its related multiplicative anomaly

The one-loop partition function for a charged self-interacting Bose gas at finite temperature in $D$-dimensional spacetime is evaluated within a path integral approach making use of zeta-function regularization. For $D$ even, a new additional vacuum term---overlooked in all previous treatments and coming from the multiplicative anomaly related to functional determinants---is found and its dependence on the mass and chemical potential is obtained. The presence of the new term is shown to be crucial for having the factorization invariance of the regularized partition function. In the noninteracting case, the relativistic Bose-Einstein condensation is reexamined. By means of a suitable charge renormalization, for $D=4$ the symmetry breaking phase is shown to be unaffected by the new term, which, however, actually gives rise to a nonvanishing new contribution in the unbroken phase.

Dynamic correlations in a charged Bose gas

Dynamic correlations in a charged Bose gas

Bose-Einstein condensation of the magnetized ideal Bose gas

We study the charged non-relativistic Bose gas interacting with a constant magnetic field but which is otherwise free. The notion of Bose-Einstein condensation for the three dimensional case is clarified, and we show that although there is no condensation in the sense of a phase transition, there is still a maximum in the specific heat which can be used to define a critical temperature. Although the absence of a phase transition persists for all values of the magnetic field, we show how as the magnetic field is reduced the curves for the specific heat approach the free field curve. For large values of the magnetic field we show that the gas undergoes a "dimensional reduction" and behaves effectively as a one-dimensional gas except at very high temperatures. These general features persist for other spatial dimensions D and we show results for D=5. Finally we examine the magnetization and the Meissner-Ochsenfeld effect.

Charged vector bosons in a magnetic field at a finite temperature

Bose-Einstein condensation does not occur in a charged vector boson gas in the presence of a homogeneous external magnetic field, although a major portion of the bosons are in the ground state. Spontaneous magnetization occurs in a vector boson gas. The total birth probability of vector boson pairs in a vacuum under a strong magnetic field at a finite temperature can be determined. Expressions that can probably characterize the vacuum free energy and magnetic moment are found, and formulas for the density and magnetic moment of the vector boson pairs generated by a magnetic field at a finite temperature are derived.

The modes of an ultra-cold strongly magnetized charged Bose gas

The modes of a strongly magnetized charged Bose gas are presented for ultra-low temperatures. For longitudinal oscillations propagating parallel to the magnetic field the dispersion relation is found to be dominated by the one-dimensional field-free plasmon dispersion relation as found by Alexandrov, Beere and Kabanov recently in reference [1], while for propagation perpendicular to the magnetic field they are found to be influenced by the cyclotron motion of the particles. Dispersion relations for these modes known as Bernstein modes are given near the cyclotron frequency and its first two harmonics. The dispersion relations for transverse modes in the system are then presented for the cases of photon propagation perpendicular and parallel to the direction of the magnetic field.

Dielectric properties of an ultra-cold weakly magnetized charged Bose gas

With a new asymptotic expansion for the specific Kummer function that appears in the response theory of low-temperature quantum plasmas in an external magnetic field, the dielectric properties of the charged Bose gas, namely its collective and transverse modes and screening properties, are evaluated in the weak-field limit.

Unexpected high energy ions from a chemical ionization source

Doubly charged rare gas cations are produced in a chemical ionization source under conditions in which the energy of the primary ionizing electrons is more than 20 eV below the energetic threshold. The formation mechanism consists of creating secondary electrons outside the ion source followed by the acceleration of some of these electrons into the source where they initiate high energy ionization processes. Evidence suggesting that the secondary electrons arise from ionizing collisions between accelerated ions and background gas is presented. This process is expected to occur generally when positive ion chemical ionization is performed in magnetic deflection instruments.

A system of parabolic equations in nonequilibrium thermodynamics including thermal and electrical effects

The time-dependent equations for a charged gas or fluid consisting of several components, exposed to an electric field, are considered. These equations form a system of strongly coupled, quasilinear parabolic equations which in some situations can be derived from the Boltzmann equation. The model uses the duality between the thermodynamic fluxes and the thermodynamic forces. Physically motivated mixed Dirichlet-Neumann boundary conditions and initial conditions are prescribed. The existence of weak solutions is proven. The key of the proof is ( i) a transformation of the problem by using the entropic variables, or electro-chemical potentials, which symmetrizes the equations, and ( ii) a priori estimates obtained by using the entropy function. Finally, the entropy inequality is employed to show the convergence of the solutions to the thermal equilibrium state as the time tends to infinity.

Breakup of a highly charged bubble in a dielectric liquid into parts of comparable size

An analysis is made of the conditions for instability of a charged gas bubble in a dielectric liquid. It is shown that unlike a charged droplet, the criterion for instability of a bubble is determined by two dimensionless parameters: the Rayleigh parameter and the ratio of the gas pressure in the parent bubble to the Laplace pressure.

Condensation and Magnetization of Charged Vector Boson Gas

The magnetic properties of charged vector boson gas are studied in the very weak, and very strong (near critical value) external magnetic field limits. When the density of the vector boson gas is low, or when the external field is strong, no true Bose–Einstein condensation occurs, though significant amount of bosons will accumulate in the ground state. The gas is ferromagnetic in nature at low temperature. However, Bose–Einstein condensation of vector bosons (scalar bosons as well) is likely to occur in the presence of a uniform weak magnetic field when the gas density is sufficiently high. A transitional density depending on the magnetic field seems to exist below which the vector boson gas changes its property with respect to the Bose–Einstein condensation in a uniform magnetic field.

Dehydration

The news that the Earth is losing 1,000 gallons of water every day is nothing for the planet's inhabitants to sweat, given the vast amount of water in the oceans. But this new information, gathered from measurements on the POLAR satellite, has shed new light on ways that water and other materials leave the atmosphere. The new data should also improve models of how the atmospheres of Earth and other planets evolve.Using a unique instrument to reduce electrical interference from the satellite, the research team took the first accurate high‐altitude measurements of the polar wind—charged gas or plasma that escapes from Earth and its ionosphere through the poles. The team, headed by Los Alamos physicist Beth Nordholt, proved that the polar wind is one mechanism by which the atomic constituents of water vapor and other atmospheric gases are dragged outward from the ionosphere, where they spiral along the planet's magnet field lines. Sunlight breaks the water into ionized hydrogen and oxygen gases in the upper atmosphere.