Static Vacuum Research Articles

Vacuum Arcs with Diffuse Cathode Attachment (Review)

The review covers the results of predominantly experimental studies of stationary vacuum arcs with diffuse cathode attachment that burns in vapor of the cathode material with a current density of less than 100 A/cm2. Such discharges are of great interest for a number of technologies that require the formation of high-intensity plasma flows without a droplet fraction. The discharges on cathodes made of graphite, pure metals, and oxides, as well as mixed cathodes, are considered. The specificity of the processes on vacuum arc cathodes is characterized by the ratio of the fluxes of thermally vaporized atoms and thermionic electrons. The review presents the results of studies of cathode materials with an atom-electron ratio of ~10–2 to ~108. Data on the working cathode temperature, the current–voltage characteristic of the discharge, the heat flux from the plasma to the cathode, the plasma parameters, its radiation spectrum, and the ion energy in the cathode jet are presented. Depending on the cathode material, the working temperature ranged from 1.2 to 2.5 kK. An analysis of the features of the charge-transfer processes on various cathodes is also presented.

Mathematical analysis and flux-based radius of influence for radon/VOC vapor intrusion mitigation systems

Volatile organic compounds (VOCs) and radon progeny pose potential health risks to occupants of certain buildings via subsurface vapor intrusion (VI) to indoor air. VI mitigation is usually performed using systems that extract gas from below the building, and the system performance is typically evaluated by measuring the distribution of applied vacuum below the floor. This article provides a new approach to assessing the radius of influence (ROI) for subslab venting systems based on mass flux instead of static vacuum distribution and includes an analyses of 121 pneumatic tests performed at 65 different suction points in 16 different buildings. The mathematical model represents a two-layer system with horizontal radial flow through transmissive material below the floor slab and vertical flow through discontinuities in the floor slab (which is simplified to approximate an equivalent porous medium). The analysis includes comparisons of the flux-based ROI to values calculated using the two-layer model for 1) vacuum, 2) velocity, and 3) travel time, which may be useful as alternative performance metrics for mitigation systems.

On the Analyticity of Static Solutions of a Field Equation in Finsler Gravity

It is well-known that static vacuum solutions of Einstein equations are analytic in suitable coordinates. We ask here for an extension of this result in the context of Finsler gravity. We consider Finsler spacetimes that retain several properties of static Lorentzian spacetimes, are Berwald and have vanishing Ricci scalar.

On the Mass of Static Metrics with Positive Cosmological Constant: II

This is the second of two works, in which we discuss the definition of an appropriate notion of mass for static metrics, in the case where the cosmological constant is positive and the model solutions are compact. In the first part, we have established a positive mass statement, characterising the de Sitter solution as the only static vacuum metric with zero mass. In this second part, we prove optimal area bounds for horizons of black hole type and of cosmological type, corresponding to Riemannian Penrose inequalities and to cosmological area bounds à la Boucher–Gibbons–Horowitz, respectively. Building on the related rigidity statements, we also deduce a uniqueness result for the Schwarzschild–de Sitter spacetime.

A UHV standard with option to be used as partial pressure standard

Partial pressure measurement has become indispensable for many applications and contributes to the complete characterization of a vacuum system. In this work, an ultrahigh vacuum (UHV) standard was established for calibrating partial pressure analyzers as a partial pressure standard, and a new method was introduced to generate standard partial pressures, which was named ‘the dynamic expansion method based on static expansion vacuum standard injection mode’. The method can produce standard partial pressures in the range from 10–5 Pa to 10–10 Pa. The relative standard uncertainty budgets of generated partial pressures (k = 1) were in the range from 2.8% up to 5.0% from 10–5 Pa to 10–9 Pa for nitrogen. Employing this method, the sensitivity calibrations of quadrupole mass spectrometry (QMS) were performed in the partial pressure range of 8.62 × 10−5 Pa to 1.51 × 10−10 Pa with single inert He, Ar, and Kr gas in secondary electron multiplier (SEM) mode. Similarly, the calibrations were carried out using active gases (H2, CH4, N2, O2, and CO2) in the range 8.56 × 10−5 Pa to 1.50 × 10−9 Pa. Additionally, the SEM gains were calibrated for these high-purity gases, on the basis of SEM gain coefficients. QMS sensitivities equivalent to Faraday cup mode were attained, and it was found that the results were approximately consistent with those of previous studies. The data were also in agreement with our theoretical calculation values excluding CH4.

N-doped carbon nanofibers from pyrolysis of free-base phthalocyanine

Heating free-base phthalocyanine (H2Pc) at around 450 °C under static vacuum results in the formation of a nonvolatile carbonaceous material through oxidative pyrolysis. We used a number of instrumental techniques to characterize its morphology and chemical composition. According to electron microscopy observations, the dominating morphology is fibrous. The estimated length of individual fibers, which appear as rather homogeneous and continuous structures, is several micrometers, with diameters of roughly 200 nm. According to elemental analysis estimates, the per cent contribution of carbon remains approximately the same as in pristine H2Pc, but about 5.4 at% of nitrogen is substituted by oxygen. Spectroscopic measurements suggest that the oxygen is incorporated into nanofiber structure in the form of different functionalities containing CO and C–OH bonds. Raman spectroscopy revealed an approximately equal contribution due to sp3 and sp2-hybridized carbon atoms, which would made one to expect that the thermal stability of nanofibers must be similar to that of defect-containing nanotubes, graphene oxide and nanodiamond. Nevertheless, according to thermogravimetric curves obtained, nanofibers are at least as thermally stable as graphene and defect-free nanotubes. Density functional theory calculations were employed to suggest possible initial steps of H2Pc oxidative pyrolysis leading to the formation of nanofibers.

Quasinormal modes of generalized black holes: δ-Kerr spacetime

The nonlinear superposition of the -metric and the Kerr metric results in a -Kerr metric that represents a deformed Kerr black hole with , where q > 0 is proportional to the nonrelativistic quadrupole moment of the collapsed configuration. We study this spacetime and determine q+ such that for q, 0 < q < q+ , the outer spacetime singularity remains a null hypersurface. In this case, -Kerr spacetime represents a generalized black hole, namely, an asymptotically flat, stationary and axisymmetric vacuum solution of general relativity for which the outer singularity is a closed null hypersurface. For an approximate variant of -Kerr spacetime characterized by mass M, quadrupole parameter q and angular momentum parameter a, where the latter two parameters are treated to first and second orders of approximation, respectively, we analytically determine the quasinormal mode (QNM) frequencies in the ray approach using the light-ring method as well as in the complementary wave approach for massless scalar field perturbations in the a = 0 limit. The QNM frequencies of -Kerr spacetime turn out to be nearly the same as those of the rotating Hartle–Thorne spacetime.

Universal black holes

We prove that a generalized Schwarzschild-like ansatz can be consistently employed to construct d-dimensional static vacuum black hole solutions in any metric theory of gravity for which the Lagrangian is a scalar invariant constructed from the Riemann tensor and its covariant derivatives of arbitrary order. Namely, we show that, apart from containing two arbitrary functions a(r) and f (r) (essentially, the gtt and grr components), in any such theory the line-element may admit as a base space any isotropy-irreducible homogeneous space. Technically, this ensures that the field equations generically reduce to two ODEs for a(r) and f (r), and dramatically enlarges the space of black hole solutions and permitted horizon geometries for the considered theories. We then exemplify our results in concrete contexts by constructing solutions in particular theories such as Gauss-Bonnet, quadratic, F(R) and F(Lovelock) gravity, and certain conformal gravities.

Elliptic boundary value problems for the stationary vacuum spacetimes

We develop a general method of proving the ellipticity of boundary value problems for the stationary vacuum spacetimes, showing that the stationary vacuum field equations are elliptic subjected to a geometrically natural collection of boundary conditions in the projection formalism. As an application, we prove that the moduli space of stationary vacuum spacetimes admits Banach manifold structure.

Ellipticity of Bartnik Boundary Data for Stationary Vacuum Spacetimes

We establish a moduli space $\mathbb E$ of stationary vacuum metrics in a spacetime, and set up a well-defined boundary map $\Pi$ in $\mathbb E$, assigning a metric class with its Bartnik boundary data. Furthermore, we prove the boundary map $\Pi$ is Fredholm by showing that the stationary vacuum equations (combined with proper gauge terms) and the Bartnik boundary conditions form an elliptic boundary value problem. As an application, we show that the Bartnik boundary data near the standard flat boundary data admits a unique (up to diffeomorphism) stationary vacuum extension locally.

From Poincar&#233;’s Electro-Gravific Ether (1905) to Cosmological Background Radiation (3&amp;deg;K, 1965)

It is well known that Einstein published in June 1905 his theory of Special Relativity (SR) without entirely based on space-time Lorentz Transformation (LT) with invariance of Light Velocity. It is much less known that Poincare published, practically at the same time, a SR also based entirely on LT with also an invariant velocity. However, according to Poincare, the invariant is not only that of light wave but also that of Gravific Wave in Ether. Poincare’s Gravific ether exerts also a Gravific pressure, in the same paper, on charged (e) Electron (a “Hole in Ether” according to Poincare). There are thus two SR: That of Einstein (ESR), without ether and without gravitation, and that of Poincare (PSR), with Electro-Gravific-Ether. The crucial question arises then: Does “SPECIAL” Poincare’s (e)-G field fall in the framework of Einstein’s GENERAL Relativity? Our answer is positive. On the basis of Einstein’s equation of gravitation (1917) with Minkowskian Metric (MM) and Zero Constant Cosmological (CC) we rediscover usual Static Vacuum (without charge e of electron). On the other hand with MM and Non-Zero CC, we discover the gravific field of a Cosmological Black Hole (CBH) with density of dark energy compatible with expanding vacuum. Hawking’s Stellar Black Hole (SBH) emits outgoing Black Radiation, whilst Poincare’s CBH emits (at time zero) incoming Black Radiation. We show that Poincare’s G-electron involves a (quantum) GRAVITON (on the model of Einstein’s quantum photon) underlying a de Broglie’s G-Wave. There is therefore a Gackground Cosmological model in Poincare’s basic paper which predicts a density and a temperature of CBR very close to the observed (COBE) values.

New Theory to Understand the Mechanism of Gravitation

Gravitation is still the least understood interaction among the fundamental forces of Nature. A new theory that explains the mechanism of gravitation and the origin Newton’s laws of gravitation and general relativity and distinguishes between two of the Newton’s laws has been proposed. It is shown that the vortex formation created during the Big Bang event is the origin of the gravitational force. The vortex curves the vacuum (space-time) around it, attract and condense energy and dust to its center to form the mass. The gradient pressure in the vortex creates a flow that upon interaction with an object transfers a part of its momentum to the object and pushes it toward the center. The force exercised on the object is equivalent to Newton’s second law. The force of attraction between two vortices is equivalent to Newton’s third law. The drag force between the energy flow of the vortex and the static vacuum diminishes the gravitational force and is equivalent to the G constant. The proposed theory could provide new interesting insights for a comprehensive understanding of gravitation and represents a theoretical starting point for the engineering of anti-gravitation technology.

New Mechanism and Analytical Formula for Understanding the Gravity Constant &amp;lt;i&amp;gt;G&amp;lt;/i&amp;gt;

The nature of gravitation and G is not well understood. A new gravitation mechanism is proposed that explains the origin and essence of the gravitational constant, G. Based on general relativity, the vacuum is considered to be a superfluid with measurable density. Rotating bodies drag vacuum and create a vortex with gradient pressure. The drag force of vacuum fluid flow in the arm of the vortex is calculated relative to the static vacuum and a value that is numerically equal to that of G is obtained. Using Archimedes’ principle, it is determined that G is the volume of vacuum displaced by a force equivalent to its weight which is equal to the drag force of the vacuum. It is concluded that the gravitational constant G expresses the force needed to displace a cubic metre of vacuum that weighs one kg in one second. Therefore, G is not a fundamental physical constant but rather is an expression of the resistance encountered by the gravitational force in the vacuum.

Simplest static and stationary vacuum quadrupolar metrics

In the present paper we argue that a special case of the Bach-Weyl metric describing a static configuration of two Schwarzschild black holes gives rise, after extending its parameter space to complex values, to a very simple 2-parameter model for the gravitational field of a static deformed mass. We compare this model, which has no restrictions on the quadrupole parameter, with the well-known Zipoy-Voorhees $\delta$-metric and show in particular that the mass quadrupole moment in the latter solution cannot take arbitrary negative values. We subsequently add an arbitrary angular momentum to our static model and study some properties of the resulting 3-parameter stationary solitonic spacetime, which permits us to introduce the notion of the Fodor-Hoenselaers-Perj\'es relativistic multipole moments.

Specific Surface and Porosity of Coal

The specific surface and porosity of Belovo coal are determined. Coal samples undergo adsorption–structural analysis at the liquid-nitrogen temperature and at different relative partial pressures, on Sorbi N.4.1 and Termosorb TPD 400 instruments and also on the Micromeritics ASAP-2020 static vacuum system.

A complete classification of S1-symmetric static vacuum black holes

In a seminal paper of 1917, Weyl presented a remarkable reduction of the static axisymmetric vacuum Einstein equations, serving as a relatively straightforward technique to generate and explore new solutions. Weyl’s reduction was used by Myers in 1987, and independently by Korotkin–Nicolai in 1994, to construct a new family of static and axisymmetric solutions with compact non-empty horizon, however with non-trivial topology and asymptotically Kasner. This family, together with the Schwarzschild and the Boost families, remained until now as the only known -symmetric static black hole solutions, namely, (metrically complete) -symmetric static vacuum solutions with compact and non-empty horizon. In this article we prove that, indeed, these three families exhaust all the examples of -symmetric static vacuum black holes.

Quantitation and identification of ethanol and inhalant compounds in whole blood using static headspace gas chromatography vacuum ultraviolet spectroscopy

Gas chromatography (GC) and vacuum ultraviolet spectroscopy (VUV) are powerful and complementary techniques for the analysis of small molecules in forensics. Most notably, flame ionization detection (FID) is commonly used with GC to identify and quantify volatile compounds. An FID's price point and ease of use makes it an attractive approach for routine laboratories that are in high demand for forensics analysis, but with the contingency that an FID relies on retention time for identification and quantification. A new and innovative method using static headspace gas chromatography coupled with vacuum ultraviolet (VUV) spectroscopy was developed for the quantitative determination of ethanol in blood and identification of inhalants. This study investigates the possibility of using VUV as an alternative technique to traditional methods that use FID and mass spectrometry (MS) in toxicology and forensic analysis. VUV brings both identification and quantitation based on Beer-Lambert's Law while using a simple single-column solution. This paper investigates 25 compounds, including ethanol, methanol, acetone, benzene, and toluene using a 130–240 nm wavelength range for identification and quantification using GC-VUV, even when coelutions occur. Ethanol was examined under a concentration range of 9 to 495 mg/dl, and the method was found to be linear with an r2 = 0.997 and a LOD of 3.1 mg/dl. Ethanol was fully separated from other volatile organic compounds (VOCs) as well as endogenous materials present in blood. Nonaromatic VOCs were analyzed at concentration ranges of 2.4 to 99 mg/dl with LODs around 0.2 mg/dl; aromatic VOCs were analyzed from 0.5 to 24 mg/dl with LODs ∼ 0.1 mg/dl.

Volume growth for geodesic balls of static vacuum space on 3-manifolds

The purpose of this article is to study the geometry of static space–times. We show that the energy density and pressure vanish on the boundary of a perfect fluid space–time, provided that it satisfies a suitable condition. Moreover, we provide an upper bound volume growth for geodesic balls of the base of static vacuum space similar to a classical result due to Bishop. In addition, we derive a weak version of the maximum principle of Omori–Yau at infinity for such spaces.

The measurement of ice nucleating particles at Tai'an city in East China

Abstract In order to make up for deficiencies in the observations of ice nucleating particles (INP) over different regions of China, the concentration of INPs and aerosol number concentrations were measured at Tai'an city in Shandong province, East China using the newly built static vacuum water vapor diffusion chamber during June 2018. The INP concentration increases with the decrease of activation temperature and the increase of water relative humidity. The average concentrations of INP at T = −20 °C were 1.57 L−1 and 4.82 L−1 at RHw = 95% and RHw = 101%, respectively. At T = −25 °C the average concentrations were 11.5 L−1 and 37.5 L−1. A high (very low) correlation was found between INP concentration and the number concentration of aerosol particles having a size in the range of 0.5–5.0 μm (

The formation of NeH+ in static vacuum mass spectrometers and re-determination of 21Ne/20Ne of air

Abstract Air-derived neon is used for routine calibration of magnetic sector mass spectrometers, principally for determining sensitivity and mass discrimination for Ne isotope determinations. The commonly accepted 21Ne/20Ne ratio of air (0.002959 ± 0.000022; Eberhardt et al. (1965) does not take account of the contribution of 20NeH+ at m/z = 21. Honda et al. (2015) and Wielandt and Storey (2019) have recently re-determined the 21Ne/20Neair by resolving 20NeH+ from 21Ne+. The 21Ne/20Neair values of the two studies differ by 1.8%, beyond the uncertainty of the measurements (±