共查询到20条相似文献,搜索用时 15 毫秒
1.
M. Girardi 《Physica A》2010,389(21):4520-4527
In this work we employ event-driven particle dynamics simulations for a system of spherical insulating grains interacting with an external electric field. This system resembles the electrostatic particle separation present on some industrial processes. Here, the particles collide inelastically with each other and with the container walls, for a constant normal and tangential restitution coefficients. During the collisions, the grains can acquire electric charge due to triboelectric contact charging, since two different species of insulating particles are mixed. Particle-particle electric interactions are not considered. Grains are also subjected to the gravitational field and rotation, and are confined in a cubic box with thermal walls in order to prevent the static equilibrium state. We calculate the mass and charge density profile, and the particle charge distribution for different values of the electric field and temperature of the walls. The particle charge distribution and the effect of particle sizes on the separation process were also investigated. 相似文献
2.
Motivated by string theory an extension of the Landau problem to quantum field theory is considered. We show that the commutator between momenta of the fields violates Lorentz and CPT invariance leading to an alternative method of understanding the question of particle–antiparticle asymmetry. The presence of magnetic field at very early moments of the universe would then suggest that the particle–antiparticle asymmetry can be understood as a consequence of magnetogenesis. 相似文献
3.
M. Lackowski A. Krupa A. Jaworek 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,56(3):377-382
Charging of aerosol droplets and solid particles is applied in many
industrial processes such as electrostatic painting, particle separation and
electrostatic precipitation. In most of charging devices, electrical
discharges are used as a source of ions, which are deposited onto the
particles. In the present paper, the charging process by ionic current in
alternating electric field was optimized experimentally. Alternating
electric field charger was used as a charging device in these experiments.
The current voltage characteristics of electrical discharge in this device,
and the charge imparted to the particles were determined. The level of
charge was measured at the outlet of the charger and was compared to the
Pauthenier limit for different supply voltages, and frequencies. MgO powder
was used as a source of particles in these experiments. It was noticed that
higher supply voltage of the charger gives higher level of particle charge,
but at the same time, the particle deposition on the charger elements was
increased, decreasing the particle penetration. A compromise between these
two tendencies is therefore necessary. As a result we have proposed a
criterion maximizing the total charge born by the particles which is a
product of relative particle charge and particle penetration. 相似文献
4.
A solution is obtained for the equations of motion of a particle in the field of a traveling electromagnetic wave propagating
between two pairs of metal surfaces of hyperbolic shape. The motion of the particle on excitation of the waveguide by monochromatic
and pulsed voltage sources is considered. The possibility of applying a quadrupole waveguide to beam focusing and the separation
of particles according to their specific charge and longitudinal velocity is investigated.
Zh. Tekh. Fiz. 67, 98–102 (July 1997) 相似文献
5.
工业过程中粉体颗粒不可避免地会相互摩擦碰撞而荷电. 荷电颗粒的存在可能会危害正常的工业生产过程, 也可能对工业过程起促进作用. 因此, 荷电粉体颗粒及其特性受到了广泛的关注, 但目前对粉体颗粒的荷电机理依然缺乏透彻的了解, 尤其是在气固两相流动中的粉体颗粒荷电现象. 事实上, 工业中存在的粉体颗粒的运动都受到流体的影响, 是典型的气固两相流系统, 流体对粉体颗粒的作用使粉体颗粒接触的荷电现象变得更为复杂, 因此从两相流动的观点来研究粉体颗粒荷电的物理本质就显得越来越重要. 本文介绍了工业过程中的几种不同类型的粉体颗粒荷电行为, 回顾了颗粒的荷电机理与描述颗粒荷电的数学模型. 对于工业过程中颗粒的荷电现象及颗粒在多相流体中的动力学行为, 介绍了研究颗粒受流体影响时荷电特性的数值模拟方法. 本文旨在对粉体颗粒的荷电机理、应用以及研究方法进行梳理与探讨, 为正确认识工业过程中粉体颗粒的荷电现象并加以控制利用提供理论借鉴. 相似文献
6.
7.
WEI Kai-Yu 《中国物理C(英文版)》1987,11(5):690-694
In this paper, a controlled annihilation principle of particles and antiparticles is suggested. The particles and antiparticles are kept in a common space by an electromagnetic field to form an equipartisma or semiequipartisma. The equipartisma and simiequipartisma are new meaterial form, they can annihilate themselves and liberate their energy at usual temperature. One may control the annihilation life-time and energy liberated speed with adjustment of the particle and antiparticle density. 相似文献
8.
Physics of Atomic Nuclei - Estimations of some geometrical and bulk parameters are presented for the matter produced in various type collisions with ultra-high energy cosmic ray (UHECR) particles.... 相似文献
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10.
It has recently been shown that black holes can act as particle accelerators and two particles can collide with arbitrarily high center-of-mass (CM) energy under certain critical conditions. In this paper, we investigate particle collisions outside a Reissner-Nordström-de Sitter (RN-dS) black hole. We find that infinite CM energy can be produced near the cosmological horizon for generic spacetime configurations. Remarkably, such infinite CM energy does not require the black hole to be extremal, in contrast to spacetimes in the absence of cosmological constants. However, since the charge of an astrophysical body is negligible, the required charge to mass ratio of the particle is extremely higher than that of any elementary particle. 相似文献
11.
Egon Marx 《International Journal of Theoretical Physics》1972,6(5):359-363
We consider a generalized Fock space obtained by eliminating the restriction to symmetric components for bosons or antisymmetric ones for fermions. In this space we can extend the many times formalism of relativistic quantum mechanics to quantum field theory, in which each particle has a time parameter that has to be included in any exchange of variables. Physical states in which all particle times, or all antiparticle times, are equal, still have the right symmetry. We define creation and annihilation operators for numbered particles in this space, and relate them to the usual operators. 相似文献
12.
O. S. Vaulina A. P. Nefedov O. F. Petrov S. A. Khrapak 《Journal of Experimental and Theoretical Physics》1999,88(6):1130-1136
The currents which charge a macroscopic particle placed in a plasma consist of discrete charges; hence, the charge can undergo
random fluctuations about its equilibrium value. These random fluctuations can be described by a simple model which, if the
mechanisms for charging of macroscopic particles are known, makes it possible to determine the dependence of the temporal
and amplitude characteristics of the fluctuations on the plasma parameters. This model can be used to study the effect of
charge fluctuations on the dynamics of the macroscopic particles. The case of so-called plasma-dust crystals (i.e., highly
ordered structures which develop because of strong interactions among macroscopic particles) in laboratory gaseous discharge
plasmas is considered as an example. The molecular dynamics method shows that, under certain conditions, random fluctuations
in the charge can effectively heat a system of macroscopic particles, thereby impeding the ordering process.
Zh. éksp. Teor. Fiz. 115, 2067–2079 (June 1999) 相似文献
13.
Bernard Mulligan 《Annals of Physics》2006,321(8):1865-1891
The two-component solutions of the Dirac equation currently in use are not separately a particle equation or an antiparticle equation. We present a unitary transformation that uncouples the four-component, force-free Dirac equation to yield a two-component spinor equation for the force-free motion of a relativistic particle and a corresponding two-component, time-reversed equation for an antiparticle. The particle-antiparticle nature of the two equations is established by applying to the solutions of these two-component equations criteria analogous to those applied for establishing the four-component particle and antiparticle solutions of the four-component Dirac equation. Wave function solutions of our two-component particle equation describe both a right and a left circularly polarized particle. Interesting characteristics of our solutions include spatial distributions that are confined in extent along directions perpendicular to the motion, without the artifice of wave packets, and an intrinsic chirality (handedness) that replaces the usual definition of chirality for particles without mass. Our solutions demonstrate that both the rest mass and the relativistic increase in mass with velocity of the force-free electron are due to an increase in the rate of Zitterbewegung with velocity. We extend this result to a bound electron, in which case the loss of energy due to binding is shown to decrease the rate of Zitterbewegung. 相似文献
14.
A. V. Uryson 《Physics of Particles and Nuclei》2006,37(3):347-367
This review is devoted to the problem of the origin of cosmic rays (CR) with energy E >4 × 1019 eV. The review mainly deals with the hypothesis of CR acceleration in active galactic nuclei (AGN). The review consists of the following five sections: Introduction, three chapters, and Conclusions. The following points are considered in Introduction: shower arrays for detecting ultra high energy cosmic rays (UHECR), the Greisen-Zatsepin-Kuzmin (GZK) cutoff, and the hypotheses of the UHECR origin. Since CRs are of extraterrestrial origin, some astrophysical data used in CR physics are presented in a special section. The identification of UHECR sources with energies E > 4 × 1019 eV is analyzed in Chapter 2. Chapter 3 deals with CR acceleration in sources and CR escape from sources. Chapter 4 is devoted to particle propagation in intergalactic space with allowance for CR interaction with the microwave background radiation and energy losses (blackbody or GZK cutoff). The propagation of UHECR protons is analyzed and their spectra at the Earth are calculated numerically. In Conclusions, we formulate the results and list the nuclear data needed to develop the model in more detail, namely, to study the propagation of CR nuclei in intergalactic space and to analyze the UHECR composition at the Earth. 相似文献
15.
A laser-Doppler instrument has been used to measure the migration velocity of NaCl particles in an electrohydrodynamic flow field of an electrical precipitator. The measured average migration velocity of 1.40-μm particles (number distribution median with a geometric standard devitation of 1.46) is approximately five to six times higher than the calculated steady-state velocity for a 1.40-μm particle, provided there is a saturation charge of at least 90f%. Further, the particle velocities in the main flow direction are also influenced by the electrical operation conditions. Both observations demonstrate the important role of the state of the electrohydrodynamic flow field (superposition of moving gas ions and neutral gas molecules) on the particle transport, characterized by the dimensionless electrohydrodynamic number NEHD. A comparison between six different electrohydrodynamic states revealed that NEHD ≈? 1 is a critical value for the mutual interactions between the gas ions and the neutral gas phase. Whereas for NEHD values > 1 the stochastic particle motion is chiefly determined by the nonsteady-state character of the negative corona, for NEHD values < 1 the particle velocity fluctuations are governed by the turbulence level of the neutral fluid. These finding might be helpful in adjusting the operating conditions in electrical precipitators for and optimized particle separation. 相似文献
16.
Suzuki Hitoshi Saito Yoshio Nakada Toshitaka Kaito Chihiro 《Journal of nanoparticle research》2002,4(5):387-394
It was found that smoke particles smaller than 100nm and of different crystal structures can be separated by an electric field. Tungsten oxide smoke curved in the electric field towards the positive electrode plate. The morphology of the particles and dispersion of particles became good in the electric field. By burning of Pb in a mixture gas of Ar (80%) and O2 (20%), red and yellow layer structure particles were simultaneously produced. The flow direction of red and yellow smokes changed by applying an electric field (200V/cm). Red particles flowed towards the negative plate and yellow particles flowed towards the positive plate, i.e. two different structures were separated. Simultaneous growth conditions of SnO and SnO2 were observed and also found that they can be separated by the use of electric field as well as lead oxides. The curve of the smoke is discussed as that the surface net charge was affected by the electric field on the basis of produced particle structure and morphology. 相似文献
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18.
B. A. Khrenov V. V. Alexandrov D. I. Bugrov G. K. Garipov N. N. Kalmykov M. I. Panasyuk S. A. Sharakin A. A. Silaev I. V. Yashin V. M. Grebenyuk D. V. Naumov A. G. Olshevsky B. M. Sabirov R. N. Semenov M. Slunechka I. I. Skryl L. G. Tkatchev O. A. Saprykin V. S. Syromyatnikov V. E. Bitkin S. A. Eremin A. I. Matyushkin F. F. Urmantsev V. Abrashin V. Koval Y. Arakcheev A. Cordero O. Martinez E. Morena C. Robledo H. Salazar L. Villasenor A. Zepeda I. Park M. Shonsky J. Zicha 《Physics of Atomic Nuclei》2004,67(11):2058-2061
The KLYPVE space experiment has been proposed to study the energy spectrum, composition, and arrival direction of ultrahigh-energy cosmic rays (UHECR) by detecting from satellites the atmosphere fluorescence and scattered Cherenkov light produced by EAS, initiated by UHECR particles. The TUS setup is a prototype KLYPVE instrument. The aim of the TUS experiment is to detect dozens of UHECR events in the energy region of the GZK cutoff, to measure the light background, to test the atmosphere control methods, and to study stability of the optical materials, PMTs, and other instrumental parts in space environment. 相似文献
20.
F. Stoffel G. Ambrosini G. Appelquist R. Arsenescu C. Baglin J. Beringer C. Bohm K. Borer A. Bussière F. Dittus K. Elsener D. Frei Ph. Gorodetzky J. P. Guillaud P. Hess E. Hugentobler S. Kabana R. Klingenberg T. Lindén K. D. Lohmann R. Mommsen U. Moser T. Pal K. Pretzl J. Schacher B. Selldén F. Stoffel J. Tuominiemi M. Weber Q. P. Zhang 《Acta Physica Hungarica A》1996,4(1-4):429-434
We searched for long-lived strange quark matter particles, so-calledstrangelets, and studied particle and antiparticle production in Pb+Pb collisions at 158 GeV/c per nucleon at zero degree production angle. We give upper limits for the production of strangelets covering a mass to charge ratio up to 120 GeV/c 2 and lifetimest lab>1.2 μs and plot invariant differential production cross sections as a function of rapidity for a variety of particles. 相似文献