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Ambipolar Electric Field
The polar wind or plasma fountain is a permanent outflow of plasma (physics), plasma from the polar regions of Earth's magnetosphere. Conceptually similar to the solar wind, it is one of several mechanisms for the Atmospheric escape, outflow of ionized particles. Ions accelerated by a polarization electric field known as an ambipolar electric field is believed to be the primary cause of polar wind. Similar processes operate on other planets. History In 1966 Bauer and, separately, Dessler ahd Michel noted that since the Earth's geomagnetic field above the poles forms a long tail away from the Sun out beyond the Moon's orbit, ions should flow from the higher pressure region in the ionosphere out into space. The term "polar wind" was coined in 1968 in a pair of articles by Banks and Holzer and by Ian Axford. Since the process by which the ionospheric plasma flows away from the Earth along magnetic field lines, is similar to the flow of solar plasma away from the Sun's corona (the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma Fountain
Plasma or plasm may refer to: Science * Plasma (physics), one of the four fundamental states of matter * Plasma (mineral), a green translucent silica mineral * Quark–gluon plasma, a state of matter in quantum chromodynamics Biology * Blood plasma, the yellow-colored liquid component of blood, in which blood cells are suspended * Cytoplasm, a jelly-like substance that fills cells, suspends and protects organelles * Germ plasm, a zone in the cytoplasm determining germ cells * Germplasm, a collection of genetic resources for an organism * Milk plasma or whey, the liquid remaining after milk has been curdled and strained * Nucleoplasm, a highly viscous liquid that surrounds the chromosomes and nucleoli * Plasma cell, white blood cells that secrete large volumes of antibodies * Protoplasm, the entire living substance inside the cell membrane or cell wall Technology * Plasma (game engine), a real-time 3D game engine from Cyan Worlds * Plasma display, a flat-panel electronic visual di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionosphere
The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on Earth. Travel through this layer also impacts GPS signals, resulting in effects such as deflection in their path and delay in the arrival of the signal. History of discovery As early as 1839, the German mathematician and physicist Carl Friedrich Gauss postulated that an electrically conducting region of the atmosphere could account for observed variations of Earth's magnetic field. Sixty years later, Guglielmo Marconi received the first trans-Atlantic radio signal on December 12, 1901, in St. John's, Newfoundland (now in Canada) usin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambipolar Diffusion
Ambipolar diffusion is diffusion of positive and negative particles with opposite electrical charge (such as electrons and positive ions) due to their interaction via an electric field. In plasma In plasma physics, ambipolar diffusion is related to the concept of quasineutrality. In most plasmas, the forces acting on the ions are different from those acting on the electrons, so naively one would expect one species to be transported faster than the other, whether by diffusion or convection or some other process. If such differential transport has a divergence, then it results in a change of the charge density. The latter will create an electric field that can alter the transport of one or both species in such a way that they become equal. The simplest example is a plasma localized in an unmagnetized vacuum. (See Inertial confinement fusion.) Both electrons and ions will stream outward with their respective thermal velocity. If the ions are relatively cold, their thermal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Error Bar
Error bars are graphical representations of the variability of data and used on graphs to indicate the error or uncertainty in a reported measurement. They give a general idea of how precise a measurement is, or conversely, how far from the reported value the true (error free) value might be. Error bars often represent one standard deviation of uncertainty, one standard error, or a particular confidence interval (e.g., a 95% interval). These quantities are not the same and so the measure selected should be stated explicitly in the graph or supporting text. Error bars can be used to compare visually two quantities if various other conditions hold. This can determine whether differences are statistically significant. Error bars can also suggest goodness of fit of a given function, i.e., how well the function describes the data. Scientific papers in the experimental sciences are expected to include error bars on all graphs, though the practice differs somewhat between sciences, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volt
The volt (symbol: V) is the unit of electric potential, Voltage#Galvani potential vs. electrochemical potential, electric potential difference (voltage), and electromotive force in the International System of Units, International System of Units (SI). Definition One volt is defined as the electric potential between two points of a electrical conductor, conducting wire when an electric current of one ampere dissipates one watt of power (physics), power between those points. It can be expressed in terms of SI base units (metre, m, kilogram, kg, second, s, and ampere, A) as : \text = \frac = \frac = \frac = \text\text^2\text^. Equivalently, it is the potential difference between two points that will impart one joule of energy per coulomb of charge that passes through it. It can be expressed in terms of SI base units (metre, m, kilogram, kg, second, s, and ampere, A) as : \text = \frac = \frac = \frac = \text\text^2\text^. It can also be expressed as amperes times ohms (curre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Svalbard
Svalbard ( , ), previously known as Spitsbergen or Spitzbergen, is a Norway, Norwegian archipelago that lies at the convergence of the Arctic Ocean with the Atlantic Ocean. North of continental Europe, mainland Europe, it lies about midway between the northern coast of Norway and the North Pole. The islands of the group range from 74th parallel north, 74° to 81st parallel north, 81° north latitude, and from 10th meridian east, 10° to 35th meridian east, 35° east longitude. The largest island is Spitsbergen (37,673 km2), followed in size by Nordaustlandet (14,443 km2), (5,073 km2), and Barentsøya (1,288 km2). Bear Island (Norway), Bjørnøya or Bear Island (178 km2) is the most southerly island in the territory, situated some 147 km south of Spitsbergen. Other small islands in the group include Hopen (Svalbard), Hopen to the southeast of Edgeøya, Kongsøya and Svenskøya in the east, and Kvitøya to the northeast. The largest settlement is Longyearbyen, situated in Isfjor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sounding Rocket
A sounding rocket or rocketsonde, sometimes called a research rocket or a suborbital rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight. The rockets are often used to launch instruments from above the surface of the Earth, the altitude generally between weather balloons and satellites; the maximum altitude for balloons is about and the minimum for satellites is approximately . Due to their suborbital flight profile, sounding rockets are often much simpler than their counterparts built for orbital flight. Certain sounding rockets have an apogee between , such as the Black Brant X and XII, which is the maximum apogee of their class. For certain purposes, sounding rockets may be flown to altitudes as high as to allow observing times of around 40 minutes to provide geophysical observations of the magnetosphere, ionosphere, thermosphere, and mesosphere. Etymology The origin of the term comes fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mach Number
The Mach number (M or Ma), often only Mach, (; ) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. It is named after the Austrian physicist and philosopher Ernst Mach. \mathrm = \frac, where: * is the local Mach number, * is the local flow velocity with respect to the boundaries (either internal, such as an object immersed in the flow, or external, like a channel), and * is the speed of sound in the medium, which in air varies with the square root of the thermodynamic temperature. By definition, at Mach1, the local flow velocity is equal to the speed of sound. At Mach0.65, is 65% of the speed of sound (subsonic), and, at Mach1.35, is 35% faster than the speed of sound (supersonic). The local speed of sound, and hence the Mach number, depends on the temperature of the surrounding gas. The Mach number is primarily used to determine the approximation with which a flow can be treated as an i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supersonic
Supersonic speed is the speed of an object that exceeds the speed of sound (Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately . Speeds greater than five times the speed of sound (Mach 5) are often referred to as hypersonic. Flights during which only some parts of the air surrounding an object, such as the ends of rotor blades, reach supersonic speeds are called transonic. This occurs typically somewhere between Mach 0.8 and Mach 1.2. Sounds are traveling vibrations in the form of pressure waves in an elastic medium. Objects move at supersonic speed when the objects move faster than the speed at which sound propagates through the medium. In gases, sound travels longitudinally at different speeds, mostly depending on the molecular mass and temperature of the gas, and pressure has little effect. Since air temperature and composition varies significantly with altitude, the speed of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen Ion
Oxygen is a chemical element; it has symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and a potent oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is the most abundant element in Earth's crust, making up almost half of the Earth's crust in the form of various oxides such as water, carbon dioxide, iron oxides and silicates.Atkins, P.; Jones, L.; Laverman, L. (2016).''Chemical Principles'', 7th edition. Freeman. It is the third-most abundant element in the universe after hydrogen and helium. At standard temperature and pressure, two oxygen atoms will bind covalently to form dioxygen, a colorless and odorless diatomic gas with the chemical formula . Dioxygen gas currently constitutes approximately 20.95% molar fraction of the Earth's atmosphere, though this has changed considerably over long periods of time in Earth's history. A much rarer triatomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
