Low-pressure Discharge
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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. It formed around 1960, once the fabrication of semiconduct ... employ low-pressure plasmas. See ...
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Gas-discharge Lamp
Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma. Typically, such lamps use a noble gas (argon, neon, krypton, and xenon) or a mixture of these gases. Some include additional substances, like mercury, sodium, and metal halides, which are vaporized during startup 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 onto the anode, while the cations thus formed are accelerated by the electric field and flow towards the cathode. Typicall ...
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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, ...
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Millitorr
The torr (symbol: Torr) is a unit of pressure based on an absolute scale, defined as exactly of a standard atmosphere (). Thus one torr is exactly (≈ ). Historically, one torr was intended to be the same as one "millimeter of mercury", but subsequent redefinitions of the two units made them slightly different (by less than ). The torr is not part of the International System of Units (SI). It is often combined with the metric prefix milli to name one millitorr (mTorr) or 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 upper-case 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 be used with prefix symbols (thus, ...
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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 ...
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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). Recombination is an exothermic reaction, meaning heat releasing reaction. Except for plasma composed of pure hydrogen (or its isotopes), there may also be multiple 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 special region of it. 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), density of each species, pressure and temperature of the surrounding environment. Uses An everyday example of rapid plasma recombination occurs when a fluorescent lamp is switched off. The ...
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Argon
Argon is a chemical element with the 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 of the 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 octe ...
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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. It formed around 1960, once the fabrication of semiconductor devices became a viable business. The industry's annual semiconductor sales revenue has since grown to over , as of 2018. The semiconductor industry is in turn the driving force behind the wider electronics industry, with annual power electronics sales of £135billion () as of 2011, annual consumer electronics sales expected to reach by 2020, tech industry sales expected to reach in 2019, and e-commerce with over in 2017. In 2019, 32.4% of the semiconductor market segment was for networks and communications devices. In 2021, the sales of semiconductors reached a record $555.9 billion, up 26.2 percent with sales in China reaching $192.5 billion, according to the Semiconductor Industry Association. A record 1.15 trillion semiconduct ...
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