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Low-pressure Discharge
Low-pressure discharges exist within Gas-discharge lamps. The electric discharges in gases are made under gas pressures from a few millitorr to a little less than atmospheric. Description They are most often used in industry to generate plasma. Less power is required to sustain the discharge at lower pressures as volume-recombination rates are lower. It is also easier to achieve uniform discharges at low pressure. Normally, the system is pumped down and only necessary plasma gases are then flown into the plasma chamber. Argon is a typical background gas because it has low ionization potential and therefore is easier to break down and sustain. Most discharges used in the semiconductor industry The semiconductor industry is the aggregate of companies engaged in the design and fabrication of semiconductors and semiconductor devices, such as transistors and integrated circuits. Its roots can be traced to the invention of the transistor ... employ low-pressure plasmas. See ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas-discharge Lamp
Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionization, ionized gas, a plasma (physics), plasma. Typically, such lamps use a noble gas (argon, neon, krypton, and xenon) or a mixture of these gases. Some include additional substances, such as mercury (element), mercury, sodium, and metal halides, which are vaporized during start-up to become part of the gas mixture. Single-ended self-starting lamps are insulated with a mica disc and contained in a borosilicate glass gas discharge tube (arc tube) and a metal cap. They include the sodium-vapor lamp that is the gas-discharge lamp in street lighting. In operation, some of the electrons are forced to leave the atoms of the gas near the anode by the electric field applied between the two electrodes, leaving these atoms positively ionized. The free electrons thus released flow to the anode, while the cations thus formed are accelerated by the electric fiel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Discharge In Gases
Electric discharge in gases occurs when electric current flows through a gaseous medium due to ionization of the gas. Depending on several factors, the discharge may radiate visible light. The properties of electric discharges in gases are studied in connection with design of lighting sources and in the design of high voltage electrical equipment. Discharge types In cold cathode tubes, the electric discharge in gas has three regions, with distinct current–voltage characteristics:Reference Data for Engineers: Radio, Electronics, Computers and Communications By Wendy Middleton, Mac E. Van Valkenburg, p. 16-42, Newnes, 2002 *I: Townsend discharge, below the breakdown voltage. At low voltages, the only current i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Millitorr
The torr (symbol: Torr) is a unit of pressure based on an absolute scale, defined as exactly of a standard atmosphere (101325 Pa). Thus one torr is exactly (≈ ). Historically, one torr was intended to be the same as one "millimetre of mercury", but subsequent redefinitions of the two units made the torr marginally lower (by less than 0.000015%). The torr is not part of the International System of Units (SI). Even so, it is often combined with the metric prefix milli to name one millitorr (mTorr), equal to 0.001 Torr. The unit was named after Evangelista Torricelli, an Italian physicist and mathematician who discovered the principle of the barometer in 1644. Nomenclature and common errors The unit name ''torr'' is written in lower case, while its symbol ("Torr") is always written with an uppercase initial; including in combinations with prefixes and other unit symbols, as in "mTorr" (millitorr) or "Torr⋅L/s" (torr-litres per second). The symbol (uppercase) should b ... [...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] |
Plasma Recombination
Plasma recombination is a process by which positive ions of a plasma capture a free (energetic) electron and combine with electrons or negative ions to form new neutral atoms ( gas). The process of recombination can be described as the reverse of ionization, whereby conditions allow the plasma to evert to a gas. Recombination is an exothermic process, meaning that the plasma releases some of its internal energy, usually in the form of heat. Except for plasma composed of pure hydrogen (or its isotopes), there may also be multiply charged ions. Therefore, a single electron capture results in decrease of the ion charge, but not necessarily in a neutral atom or molecule. Recombination usually takes place in the whole volume of a plasma (volume recombination), although in some cases it is confined to some region of the volume. Each kind of reaction is called a recombining mode and their individual rates are strongly affected by the properties of the plasma such as its energy (heat), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argon
Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abundant as water vapor (which averages about 4000 ppmv, but varies greatly), 23 times as abundant as carbon dioxide (400 ppmv), and more than 500 times as abundant as neon (18 ppmv). Argon is the most abundant noble gas in Earth's crust, comprising 0.00015% of the crust. Nearly all argon in Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in Earth's crust. In the universe, argon-36 is by far the most common argon isotope, as it is the most easily produced by stellar nucleosynthesis in supernovas. The name "argon" is derived from the Greek word , neuter singular form of meaning 'lazy' or 'inactive', as a reference to the fact that the element undergoes almost no chemical reactions. The complete oc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiconductor Industry
The semiconductor industry is the aggregate of companies engaged in the design and fabrication of semiconductors and semiconductor devices, such as transistors and integrated circuits. Its roots can be traced to the invention of the transistor by Shockley, Brattain, and Bardeen at Bell Labs in 1948. Bell Labs licensed the technology for $25,000, and soon many companies, including Motorola (1952), Schockley Semiconductor (1955), Sylvania, Centralab, Fairchild Semiconductor and Texas Instruments were making transistors. In 1958 Jack Kilby of Texas Instruments and Robert Noyce of Fairchild independently invented the Integrated Circuit, a method of producing multiple transistors on a single "chip" of Semiconductor material. This kicked off a number of rapid advances in fabrication technology leading to the exponential growth in semiconductor device production, known as Moore's law that has persisted over the past six or so decades. The industry's annual semiconductor sale ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
