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Plasmoid
A plasmoid is a coherent structure of Plasma (physics), plasma and magnetic fields. Plasmoids have been proposed to explain natural phenomena such as ball lightning, magnetic bubbles in the magnetosphere, and objects in cometary tails, in the solar wind, solar atmosphere, and in the heliospheric current sheet. Plasmoids produced in the laboratory include the compact toroids (similar to a vortex ring in low temperature fluid dynamics or hydrodynamics) field-reversed configurations, spheromaks, and filamentary variants in dense plasma focuses. The word ''plasmoid'' was coined in 1956 by Winston H. Bostick (1916–1991) to mean a "plasma-magnetic entity": Plasmoid characteristics Bostick researched the basic traits, and many details, of plasmoids. A plasmoid has an internal pressure stemming from both the gas pressure of the plasma and the magnetic pressure of the field. To maintain an approximately static plasmoid radius, this pressure must be balanced by an external confini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dense Plasma Focus
A dense plasma focus (DPF) is a type of Plasma (physics), plasma generating system originally developed as a fusion power device, starting in the early 1960s. The system demonstrated Power law, scaling laws that suggested it would not be useful in the commercial power role, and since the 1980s it has been used mainly as a fusion teaching system, and as a source of neutrons and X-rays. The original concept was developed in 1954 in the Soviet Union by N.V. Filippov, who noticed the effect while working on early ''Pinch (plasma physics), pinch'' machines. A major research program on DPF was carried out in the USSR through the late 1950s, and continues to this day. A different version of the same basic concept was independently discovered in the US by J.W. Mather in the early 1960s. This version saw some development in the 1970s, and variations continue to be developed. The basic design derives from the Z-pinch concept. Both the DPF and pinch use large electrical currents run through a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ball Lightning
Ball lightning is a rare and unexplained phenomenon described as Luminosity, luminescent, spherical objects that vary from pea-sized to several meters in diameter. Though usually associated with thunderstorms, the observed phenomenon is reported to last considerably longer than the split-second flash of a lightning strike, lightning bolt, and is a phenomenon distinct from St. Elmo's fire and will-o'-the-wisp. Some 19th-century reports describe balls that eventually explode and leave behind an odor of sulfur. Descriptions of ball lightning appear in a variety of accounts over the centuries and have received attention from scientists. An optical spectrum of what appears to have been a ball lightning event was published in January 2014 and included a video at high frame rate. Nevertheless, scientific data on ball lightning remain scarce. Although laboratory experiments have produced effects that are visually similar to reports of ball lightning, how these relate to the supposed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compact Toroid
A compact toroid (CT) is a type of plasmoid, a class of toroidal plasma configuration that is self-stable, and which does not need magnet coils running through the center of the toroid. They are studied mainly in the field of fusion power, where a lack of complex magnets and a simple geometry may allow building dramatically simpler and less costly fusion reactors. The two best studied compact toroids are the spheromak and field-reversed configuration (FRC). A third configuration, the particle ring, lacks attractive performance to date. A CT containment system for plasma asymmetrically toroidally shaped by the containment, was first introduced into thought as a concept by Alfvén. The two examplar types; Field-reversed configuration plasma with a null toroid, firstly, is generally produced by prolate-theta-pinches with the necessarily existing field condition where the field magnetic bias is in a reversed situation. The second type has a non-null toroid, known as a spheromak co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spheromak
A spheromak is an arrangement of plasma formed into a toroidal shape similar to a smoke ring. The spheromak contains large internal electric currents and their associated magnetic fields arranged so the magnetohydrodynamic forces within the spheromak are nearly balanced, resulting in long-lived (microsecond) confinement times without external fields. Spheromaks belong to a type of plasma configuration referred to as the compact toroids. A spheromak can be made and sustained using magnetic flux injection, leading to a dynomak. The physics of the spheromak and of collisions between spheromaks is similar to a variety of astrophysical events, like coronal loops and filaments, relativistic jets and plasmoids. They are particularly useful for studying magnetic reconnection events, when two or more spheromaks collide. Spheromaks are easy to generate using a "gun" that ejects spheromaks off the end of an electrode into a holding area, called the flux conserver. This has made them u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heliospheric Current Sheet
The heliospheric current sheet, or interplanetary current sheet, is a surface separating regions of the heliosphere where the interplanetary magnetic field points toward and away from the Sun. A small electrical current with a current density of about 10−10 A/m2 flows within this surface, forming a current sheet confined to this surface.Israelevich, P. L., ''et al.'',MHD simulation of the three-dimensional structure of the heliospheric current sheet" (2001) ''Astronomy and Astrophysics'', v.376, p.288–291 The shape of the current sheet results from the influence of the Sun's rotating magnetic field on the plasma in the interplanetary medium. The thickness of the current sheet is about near the orbit of the Earth. Characteristics Ballerina's skirt shape As the Sun rotates, its magnetic field twists into an Archimedean spiral, as it extends through the Solar System. This phenomenon is often called the Parker spiral, after Eugene Parker's workParker, E. N.,Dynamics of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetosphere
In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo theory, dynamo. In the space environment close to a planetary body with a dipole magnetic field such as Earth, the field lines resemble a simple magnetic dipole. Farther out, field lines can be significantly distorted by the flow of electrically conducting plasma (physics), plasma, as emitted from the Sun (i.e., the solar wind) or a nearby star. Planets having active magnetospheres, like the Earth, are capable of mitigating or blocking the effects of solar radiation or cosmic radiation. Interactions of particles and atmospheres with magnetospheres are studied under the specialized scientific subjects of plasma physics, space physics, and aeronomy. History Study of Earth's magnetosphere began in 1600, when William Gilbert (astronomer), W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vortex Ring
A vortex ring, also called a toroidal vortex, is a torus-shaped vortex in a fluid; that is, a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. The dominant flow in a vortex ring is said to be toroidal, more precisely poloidal. Vortex rings are plentiful in turbulent flows of liquids and gases, but are rarely noticed unless the motion of the fluid is revealed by suspended particles—as in the smoke rings which are often produced intentionally or accidentally by smokers. Fiery vortex rings are also a commonly produced trick by fire eaters. Visible vortex rings can also be formed by the firing of certain artillery, in mushroom clouds, in microbursts, and rarely in volcanic eruptions. A vortex ring usually tends to move in a direction that is perpendicular to the plane of the ring and such that the inner edge of the ring moves faster forward than the outer edge. Within a stationary body of fluid, a vortex ring can travel for relative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Dynamics
In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in motion) and (the study of water and other liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moment (physics), moments on aircraft, determining the mass flow rate of petroleum through pipeline transport, pipelines, weather forecasting, predicting weather patterns, understanding nebulae in interstellar space, understanding large scale Geophysical fluid dynamics, geophysical flows involving oceans/atmosphere and Nuclear weapon design, modelling fission weapon detonation. Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma (physics)
Plasma () is a state of matter characterized by the presence of a significant portion of charged particles in any combination of ions or electrons. It is the most abundant form of ordinary matter in the universe, mostly in stars (including the Sun), but also dominating the rarefied intracluster medium and Outer space#Intergalactic space, intergalactic medium. Plasma can be artificially generated, for example, by heating a neutral gas or subjecting it to a strong electromagnetic field. The presence of charged particles makes plasma electrically conductive, with the dynamics of individual particles and macroscopic plasma motion governed by collective electromagnetic fields and very sensitive to externally applied fields. The response of plasma to electromagnetic fields is used in many modern devices and technologies, such as plasma display, plasma televisions or plasma etching. Depending on temperature and density, a certain number of neutral particles may also be present, in wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Field
A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function (mathematics), function assigning a Euclidean vector, vector to each point of space, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
