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Runaway Breakdown
Runaway breakdown is a theory of lightning initiation proposed by Alex Gurevich in 1992. Electrons in air have a mean free path of ~1 cm. Fast electrons which move at a large fraction of the speed of light have a mean free path up to 100 times longer. Given the long free paths, an electric field can accelerate these electrons to energies far higher than that of initially static electrons. If they strike air molecules, more relativistic electrons will be released, creating an avalanche multiplication of "runaway" electrons. This process, relativistic runaway electron avalanche, has been hypothesized to lead to electrical breakdown in thunderstorms, but only when a source of high-energy electrons from a cosmic ray is present to start the "runaway" process. The resulting conductive plasma trail, many tens of meters long, is suggested to supply the "seed" which triggers a lightning flash. See also * List of plasma (physics) articles * Spark gap * Avalanche breakdown * Ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightning
Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous release of an average of one Joule, gigajoule of energy. This discharge may produce a wide range of electromagnetic radiation, from heat created by the rapid movement of electrons, to brilliant flashes of visible light in the form of black-body radiation. Lightning causes thunder, a sound from the shock wave which develops as gases in the vicinity of the discharge experience a sudden increase in pressure. Lightning occurs commonly during thunderstorms as well as other types of energetic weather systems, but volcanic lightning can also occur during volcanic eruptions. The three main kinds of lightning are distinguished by where they occur: either inside a single Cumulonimbus cloud, thundercloud (intra-cloud), between two clouds (cloud-to-cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alex Gurevich
Aleksandr (Alex) Viktorovich Gurevich (russian: Александр Викторович Гуревич) (b. September 19, 1930) is a Soviet and Russian physicist. In 1992 he proposed the theory of lightning initiation known as the "runaway breakdown". Gurevich graduated from Moscow State University in 1952. In 1984 he became a Corresponding Member of the USSR Academy of Sciences (Russian Academy of Sciences since 1991). He was the head of the I. E. Tamm Theoretical Department at the Lebedev Physical Institute. From 2010 he is the head of Academic Department of Physics and Astrophysics Problems in Moscow Institute of Physics and Technology. Fields of Research His work has focused on: * Plasma kinetics (1955-) * Ionospheric physics (1955-) * Nonlinear dynamics of non-collisional plasmas (1963-) * Nonlinear waves in dispersive hydrodynamics (1973-) * Artificial ionized layers in the atmosphere (1977-) * The electrodynamics of neutron star magnetospheres (1983–1993) * Nonlinear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron's mass is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum ( spin) of a half-integer value, expressed in units of the reduced Planck constant, . Being fermions, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: They can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mean Free Path
In physics, mean free path is the average distance over which a moving particle (such as an atom, a molecule, or a photon) travels before substantially changing its direction or energy (or, in a specific context, other properties), typically as a result of one or more successive collisions with other particles. Scattering theory Imagine a beam of particles being shot through a target, and consider an infinitesimally thin slab of the target (see the figure). The atoms (or particles) that might stop a beam particle are shown in red. The magnitude of the mean free path depends on the characteristics of the system. Assuming that all the target particles are at rest but only the beam particle is moving, that gives an expression for the mean free path: :\ell = (\sigma n)^, where is the mean free path, is the number of target particles per unit volume, and is the effective cross-sectional area for collision. The area of the slab is , and its volume is . The typical number of st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speed Of Light
The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit for the speed at which conventional matter or energy (and thus any signal carrying information) can travel through space. All forms of electromagnetic radiation, including visible light, travel at the speed of light. For many practical purposes, light and other electromagnetic waves will appear to propagate instantaneously, but for long distances and very sensitive measurements, their finite speed has noticeable effects. Starlight viewed on Earth left the stars many years ago, allowing humans to study the history of the universe by viewing distant objects. When communicating with distant space probes, it can take minutes to hours for signals to travel from Earth to the spacecraft and vice versa. In computing, the speed of light fixes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Field
An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field for a system of charged particles. Electric fields originate from electric charges and time-varying electric currents. Electric fields and magnetic fields are both manifestations of the electromagnetic field, one of the four fundamental interactions (also called forces) of nature. Electric fields are important in many areas of physics, and are exploited in electrical technology. In atomic physics and chemistry, for instance, the electric field is the attractive force holding the atomic nucleus and electrons together in atoms. It is also the force responsible for chemical bonding between atoms that result in molecules. The electric field is defined as a vector field that associates to each point in space the electrostatic ( Coulomb) for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theory Of Relativity
The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical phenomena in the absence of gravity. General relativity explains the law of gravitation and its relation to the forces of nature. It applies to the cosmological and astrophysical realm, including astronomy. The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old Classical mechanics, theory of mechanics created primarily by Isaac Newton. It introduced concepts including 4-dimensional spacetime as a unified entity of space and time in physics, time, relativity of simultaneity, kinematics, kinematic and gravity, gravitational time dilation, and length contraction. In the field of physics, relativity improved the science of elementary particles and their fundamental interactions, along with ushering in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relativistic Runaway Electron Avalanche
A relativistic runaway electron avalanche (RREA) is an avalanche growth of a population of relativistic electrons driven through a material (typically air) by an electric field. RREA has been hypothesized to be related to lightning initiation, terrestrial gamma-ray flashes, sprite lightning, and spark development. RREA is unique as it can occur at electric fields an order of magnitude lower than the dielectric strength of the material. Mechanism When an electric field is applied to a material, free electrons will drift slowly through the material as described by the electron mobility. For low-energy electrons, faster drift velocities result in more interactions with surrounding particles. These interactions create a form of friction that slow the electrons down. Thus, for low-energy cases, the electron velocities tend to stabilize. At higher energies, above about 100 keV, these collisional events become less common as the mean free path of the electron rises. These higher-energ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Breakdown
Electrical breakdown or dielectric breakdown is a process that occurs when an electrical insulating material, subjected to a high enough voltage, suddenly becomes an electrical conductor and electric current flows through it. All insulating materials undergo breakdown when the electric field caused by an applied voltage exceeds the material's dielectric strength. The voltage at which a given insulating object becomes conductive is called its breakdown voltage and in addition to its dielectric strength depends on its size and shape, and the location on the object at which the voltage is applied. Under sufficient electrical potential, electrical breakdown can occur within solids, liquids, or gases (and theoretically even in a vacuum). However, the specific breakdown mechanisms are different for each kind of dielectric medium. Electrical breakdown may be a momentary event (as in an electrostatic discharge), or may lead to a continuous electric arc if protective devices fail to int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmic Ray
Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own galaxy, and from distant galaxies. Upon impact with Earth's atmosphere, cosmic rays produce showers of secondary particles, some of which reach the surface, although the bulk is deflected off into space by the magnetosphere or the heliosphere. Cosmic rays were discovered by Victor Hess in 1912 in balloon experiments, for which he was awarded the 1936 Nobel Prize in Physics. Direct measurement of cosmic rays, especially at lower energies, has been possible since the launch of the first satellites in the late 1950s. Particle detectors similar to those used in nuclear and high-energy physics are used on satellites and space probes for research into cosmic rays. Data from the Fermi Space Telescope (2013) have been interpreted as evidenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma (physics)
Plasma () 1, where \nu_ is the electron gyrofrequency and \nu_ is the electron collision rate. It is often the case that the electrons are magnetized while the ions are not. Magnetized plasmas are ''anisotropic'', meaning that their properties in the direction parallel to the magnetic field are different from those perpendicular to it. While electric fields in plasmas are usually small due to the plasma high conductivity, the electric field associated with a plasma moving with velocity \mathbf in the magnetic field \mathbf is given by the usual Lorentz force, Lorentz formula \mathbf = -\mathbf\times\mathbf, and is not affected by Debye shielding. Mathematical descriptions To completely describe the state of a plasma, all of the particle locations and velocities that describe the electromagnetic field in the plasma region would need to be written down. However, it is generally not practical or necessary to keep track of all the particles in a plasma. Therefore, plasma physicist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Plasma (physics) Articles
This is a list of plasma physics topics. A * Ablation * Abradable coating * Abraham–Lorentz force * Absorption band * Accretion disk * Active galactic nucleus * Adiabatic invariant * ADITYA (tokamak) * Aeronomy * Afterglow plasma * Airglow * Air plasma, Corona treatment, Atmospheric-pressure plasma treatment * Ayaks, Novel "Magneto-plasmo-chemical engine" * Alcator C-Mod * Alfvén wave * Ambipolar diffusion * Aneutronic fusion * Anisothermal plasma * Anisotropy * Antiproton Decelerator * Appleton-Hartree equation * Arcing horns * Arc lamp * Arc suppression * ASDEX Upgrade, Axially Symmetric Divertor EXperiment * Astron (fusion reactor) * Astronomy * Astrophysical plasma * Astrophysical X-ray source * Atmospheric dynamo * Atmospheric escape * Atmospheric pressure discharge * Atmospheric-pressure plasma * Atom * Atomic emission spectroscopy * Atomic physics * Atomic-terrace low-angle shadowing * Auger electron spectroscopy * Aurora (astronomy) B * Babcock Model * Bal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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