1.
Tron
–
Tron is a 1982 American science fiction action-adventure film written and directed by Steven Lisberger, based on a story by Lisberger and Bonnie MacBird and produced by Walt Disney Productions. The film stars Jeff Bridges as a programmer who is transported inside the software world of a mainframe computer where he interacts with programs in his attempt to escape. Bruce Boxleitner, David Warner, Cindy Morgan, and Barnard Hughes star in supporting roles, development of Tron began in 1976 when Lisberger became fascinated with the early video game Pong. He and producer Donald Kushner set up a studio to develop Tron with the intention of making it an animated film. Indeed, to promote the studio itself, Lisberger and his created a 30-second animation featuring the first appearance of the eponymous character. Eventually, Lisberger decided to include elements with both backlit and computer animation for the actual feature-length film. Various film studios had rejected the storyboards for the film before Walt Disney Studios agreed to finance, there, backlit animation was finally combined with the computer animation and live action. Tron was released on July 9,1982 in 1,091 theaters in the United States, the film was a moderate success at the box office, and received positive reviews from critics who praised the groundbreaking visuals and acting. However, the storyline was criticized at the time for being incoherent, Tron received nominations for Best Costume Design and Best Sound at the 55th Academy Awards, and received the Academy Award for Technical Achievement fourteen years later. Over time, Tron developed into a film and eventually spawned a franchise, which consists of multiple video games, comic books. A sequel titled Tron, Legacy directed by Joseph Kosinski was released on December 17,2010, with Bridges and Boxleitner reprising their roles, Kevin Flynn is a software engineer, formerly employed by the computer corporation ENCOM, who now runs a video arcade called Flynns. He wrote several video games, but Ed Dillinger, another ENCOM engineer, stole them and passed them off as his own, Flynns ex-girlfriend Lora Baines and fellow ENCOM engineer Alan Bradley warn Flynn that Dillinger knows about his hacking attempts and has tightened security. Flynn persuades them to him inside ENCOM where he forges Group 6 access for the group. He goes to a terminal in Loras lab to continue searching for evidence of Dillingers theft, Flynn quickly learns that the MCP and its second-in-command, Sark, rule over programs and coerce them to renounce their belief in the Users. Those who resist the MCPs tyrannical power over the Grid are forced to play in games in which the losers are destroyed. Flynn is forced to other programs and meets Tron and Ram between matches. The three escape into the mainframe during a Light Cycle match, but shortly afterwards Flynn and Ram are separated from Tron by an MCP pursuit party composed of tanks based on code Flynn wrote. When Ram is mortally wounded and dies, Flynn learns that as a User he can manipulate energy and matter inside the Grid, effectively allowing him to influence the environment and he uses his abilities to make a destroyed pursuit ship piece itself together, effectively repairing it
Tron
–
Theatrical release poster
2.
Infrared
–
It extends from the nominal red edge of the visible spectrum at 700 nanometers, to 1000000 nm. Most of the radiation emitted by objects near room temperature is infrared. Like all EMR, IR carries radiant energy, and behaves both like a wave and like its quantum particle, the photon, slightly more than half of the total energy from the Sun was eventually found to arrive on Earth in the form of infrared. The balance between absorbed and emitted infrared radiation has an effect on Earths climate. Infrared radiation is emitted or absorbed by molecules when they change their rotational-vibrational movements and it excites vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. Infrared spectroscopy examines absorption and transmission of photons in the infrared range, Infrared radiation is used in industrial, scientific, and medical applications. Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected, Infrared thermal-imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect overheating of electrical apparatuses. Thermal-infrared imaging is used extensively for military and civilian purposes, military applications include target acquisition, surveillance, night vision, homing, and tracking. Humans at normal body temperature radiate chiefly at wavelengths around 10 μm, Infrared radiation extends from the nominal red edge of the visible spectrum at 700 nanometers to 1 mm. This range of wavelengths corresponds to a range of approximately 430 THz down to 300 GHz. Below infrared is the portion of the electromagnetic spectrum. Sunlight, at a temperature of 5,780 kelvins, is composed of near thermal-spectrum radiation that is slightly more than half infrared. At zenith, sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level, of this energy,527 watts is infrared radiation,445 watts is visible light, and 32 watts is ultraviolet radiation. Nearly all the radiation in sunlight is near infrared, shorter than 4 micrometers. On the surface of Earth, at far lower temperatures than the surface of the Sun, almost all thermal radiation consists of infrared in mid-infrared region, much longer than in sunlight. Of these natural thermal radiation processes only lightning and natural fires are hot enough to produce much visible energy, thermal infrared radiation also has a maximum emission wavelength, which is inversely proportional to the absolute temperature of object, in accordance with Wiens displacement law. Therefore, the band is often subdivided into smaller sections. Due to the nature of the blackbody radiation curves, typical hot objects, such as exhaust pipes, the three regions are used for observation of different temperature ranges, and hence different environments in space
Infrared
–
This infrared space telescope image has (false color) blue, green and red corresponding to 3.4, 4.6, and 12
µm wavelengths, respectively.
Infrared
–
A
false color image of two people taken in long-wavelength infrared (body-temperature thermal) light.
Infrared
–
Materials with higher
emissivity appear to be hotter. In this thermal image, the ceramic cylinder appears to be hotter than its cubic container (made of silicon carbide), while in fact they have the same temperature.
Infrared
–
Active-infrared night vision: the camera illuminates the scene at infrared wavelengths invisible to the
human eye. Despite a dark back-lit scene, active-infrared night vision delivers identifying details, as seen on the display monitor.
3.
Neodymium
–
Neodymium is a chemical element with symbol Nd and atomic number 60. It is a silvery metal that tarnishes in air. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach and it is present in significant quantities in the ore minerals monazite and bastnäsite. Neodymium is not found naturally in form or unmixed with other lanthanides. Although neodymium is classed as an earth, it is a fairly common element, no rarer than cobalt, nickel, and copper. Most of the worlds commercial neodymium is mined in China, neodymium compounds were first commercially used as glass dyes in 1927, and they remain a popular additive in glasses. Some neodymium-doped glasses are used in lasers that emit infrared with wavelengths between 1047 and 1062 nanometers. These have been used in applications, such as experiments in inertial confinement fusion. Neodymium is also used various other substrate crystals, such as yttrium aluminum garnet in the Nd. This laser usually emits infrared at a wavelength of about 1064 nanometers, the Nd, YAG laser is one of the most commonly used solid-state lasers. Another important use of neodymium is as a component in the used to make high-strength neodymium magnets—powerful permanent magnets. Larger neodymium magnets are used in electric motors and generators. Neodymium, a rare metal, was present in the classical mischmetal at a concentration of about 18%. Metallic neodymium has a bright, silvery luster, but as one of the more reactive lanthanide rare-earth metals. The oxide layer forms then peels off, exposing the metal to further oxidation, thus, a centimeter-sized sample of neodymium completely oxidizes within a year. Neodymium commonly exists in two forms, with a transformation from a double hexagonal to a body-centered cubic structure taking place at about 863 °C. Naturally occurring neodymium is a mixture of five stable isotopes, 142Nd, 143Nd, 145Nd, 146Nd and 148Nd, with 142Nd being the most abundant, and two radioisotopes, 144Nd and 150Nd. In all,31 radioisotopes of neodymium have been detected as of 2010, with the most stable radioisotopes being the naturally occurring ones, 144Nd and 150Nd
Neodymium
–
Neodymium, 60 Nd
Neodymium
–
Neodymium(III)-sulfate
Neodymium
–
Neodymium compounds in
fluorescent tube light—from left to right, the sulfate, nitrate, and chloride
Neodymium
–
Neodymium compounds in
CFL light
4.
Glass
–
Glass is a non-crystalline amorphous solid that is often transparent and has widespread practical, technological, and decorative usage in, for example, window panes, tableware, and optoelectronics. The most familiar, and historically the oldest, types of glass are silicate glasses based on the chemical compound silica, the primary constituent of sand. The term glass, in usage, is often used to refer only to this type of material. Many applications of silicate glasses derive from their optical transparency, giving rise to their use as window panes. Glass can be coloured by adding metallic salts, and can also be painted and printed with vitreous enamels and these qualities have led to the extensive use of glass in the manufacture of art objects and in particular, stained glass windows. Although brittle, silicate glass is extremely durable, and many examples of glass fragments exist from early glass-making cultures, because glass can be formed or moulded into any shape, it has been traditionally used for vessels, bowls, vases, bottles, jars and drinking glasses. In its most solid forms it has also used for paperweights, marbles. Some objects historically were so commonly made of glass that they are simply called by the name of the material, such as drinking glasses. Porcelains and many polymer thermoplastics familiar from everyday use are glasses and these sorts of glasses can be made of quite different kinds of materials than silica, metallic alloys, ionic melts, aqueous solutions, molecular liquids, and polymers. For many applications, like glass bottles or eyewear, polymer glasses are a lighter alternative than traditional glass, silica is a common fundamental constituent of glass. In nature, vitrification of quartz occurs when lightning strikes sand, forming hollow, fused quartz is a glass made from chemically-pure SiO2. It has excellent resistance to shock, being able to survive immersion in water while red hot. However, its high melting-temperature and viscosity make it difficult to work with, normally, other substances are added to simplify processing. One is sodium carbonate, which lowers the transition temperature. The soda makes the glass water-soluble, which is undesirable, so lime, some magnesium oxide. The resulting glass contains about 70 to 74% silica by weight and is called a soda-lime glass, soda-lime glasses account for about 90% of manufactured glass. Most common glass contains other ingredients to change its properties, lead glass or flint glass is more brilliant because the increased refractive index causes noticeably more specular reflection and increased optical dispersion. Adding barium also increases the refractive index, iron can be incorporated into glass to absorb infrared energy, for example in heat absorbing filters for movie projectors, while cerium oxide can be used for glass that absorbs UV wavelengths
Glass
–
The joining of two tubes made of
lead glass during
glass welding.
Glass
–
Moldavite, a natural glass formed by
meteorite impact, from
Besednice, Bohemia
Glass
–
Tube fulgurites
Glass
–
Quartz sand (silica) is the main raw material in commercial glass production
5.
Laser
–
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term laser originated as an acronym for light amplification by stimulated emission of radiation, the first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow. A laser differs from other sources of light in that it emits light coherently, spatial coherence allows a laser to be focused to a tight spot, enabling applications such as laser cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over great distances, Lasers can also have high temporal coherence, which allows them to emit light with a very narrow spectrum, i. e. they can emit a single color of light. Temporal coherence can be used to produce pulses of light as short as a femtosecond, Lasers are distinguished from other light sources by their coherence. Spatial coherence is typically expressed through the output being a narrow beam, Laser beams can be focused to very tiny spots, achieving a very high irradiance, or they can have very low divergence in order to concentrate their power at a great distance. Temporal coherence implies a polarized wave at a single frequency whose phase is correlated over a great distance along the beam. A beam produced by a thermal or other incoherent light source has an amplitude and phase that vary randomly with respect to time and position. Lasers are characterized according to their wavelength in a vacuum, most single wavelength lasers actually produce radiation in several modes having slightly differing frequencies, often not in a single polarization. Although temporal coherence implies monochromaticity, there are lasers that emit a broad spectrum of light or emit different wavelengths of light simultaneously, there are some lasers that are not single spatial mode and consequently have light beams that diverge more than is required by the diffraction limit. However, all devices are classified as lasers based on their method of producing light. Lasers are employed in applications where light of the spatial or temporal coherence could not be produced using simpler technologies. The word laser started as an acronym for light amplification by stimulated emission of radiation, in the early technical literature, especially at Bell Telephone Laboratories, the laser was called an optical maser, this term is now obsolete. A laser that produces light by itself is technically an optical rather than an optical amplifier as suggested by the acronym. It has been noted that the acronym LOSER, for light oscillation by stimulated emission of radiation. With the widespread use of the acronym as a common noun, optical amplifiers have come to be referred to as laser amplifiers. The back-formed verb to lase is frequently used in the field, meaning to produce light, especially in reference to the gain medium of a laser. Further use of the laser and maser in an extended sense, not referring to laser technology or devices, can be seen in usages such as astrophysical maser
Laser
–
United States Air Force laser experiment
Laser
–
Red (660 & 635 nm), green (532 & 520 nm) and blue-violet (445 & 405 nm) lasers
Laser
–
Laser beams in fog, reflected on a car windshield
Laser
6.
Lawrence Livermore National Laboratory
–
Lawrence Livermore National Laboratory is an American federal research facility in Livermore, California, United States, founded by the University of California in 1952. A Federally Funded Research and Development Center, it is funded by the U. S. In 2012, the laboratory had the synthetic chemical element livermorium named after it, LLNL is self-described as a premier research and development institution for science and technology applied to national security. Its principal responsibility is ensuring the safety, security and reliability of the nuclear weapons through the application of advanced science, engineering. The Laboratory is located on a site at the eastern edge of Livermore. It also operates a 7,000 acres remote experimental test site, called Site 300, LLNL has an annual budget of about $1.5 billion and a staff of roughly 5,800 employees. LLNL was established in 1952 as the University of California Radiation Laboratory at Livermore and it was intended to spur innovation and provide competition to the nuclear weapon design laboratory at Los Alamos in New Mexico, home of the Manhattan Project that developed the first atomic weapons. Edward Teller and Ernest Lawrence, director of the Radiation Laboratory at Berkeley, are regarded as the co-founders of the Livermore facility, the new laboratory was sited at a former naval air station of World War II. About half an hour southeast of Berkeley, the Livermore site provided much greater security for classified projects than a university campus. Lawrence tapped 32-year-old Herbert York, a graduate student of his. Under York, the Lab had four programs, Project Sherwood, Project Whitney, diagnostic weapon experiments. Lawrence died in August 1958 and shortly after, the board of regents named both laboratories for him, as the Lawrence Radiation Laboratory. Historically, the Berkeley and Livermore laboratories have had close relationships on research projects, business operations. The Livermore Lab was established initially as a branch of the Berkeley Laboratory, the Livermore Lab was not officially severed administratively from the Berkeley Lab until 1971. The laboratory was renamed Lawrence Livermore Laboratory in 1971, on October 1,2007 LLNS assumed management of LLNL from the University of California, which had exclusively managed and operated the Laboratory since its inception 55 years before. The laboratory was honored in 2012 by having the chemical element livermorium named after it. The LLNS takeover of the Laboratory has been controversial, in May 2013, an Alameda County jury awarded over $2.7 million to five former Laboratory employees who were among 430 employees LLNS laid off during 2008. The jury found that LLNS breached an obligation to terminate the employees only for “reasonable cause. ”The five plaintiffs also have pending age discrimination claims against LLNS
Lawrence Livermore National Laboratory
–
Aerial view of Lawrence Livermore National Laboratory
7.
Inertial confinement fusion
–
The heated outer layer explodes outward, producing a reaction force against the remainder of the target, accelerating it inwards, compressing the target. This process is designed to shock waves that travel inward through the target. A sufficiently powerful set of waves can compress and heat the fuel at the center so much that fusion reactions occur. The energy released by these reactions will then heat the surrounding fuel, the aim of ICF is to produce a condition known as ignition, where this heating process causes a chain reaction that burns a significant portion of the fuel. ICF is one of two branches of fusion energy research, the other being magnetic confinement fusion. When it was first proposed in the early 1970s, ICF appeared to be an approach to fusion power production. Experiments during the 1970s and 80s demonstrated that the efficiency of devices was much lower than expected. Throughout the 1980s and 90s, many experiments were conducted in order to understand the interaction of high-intensity laser light. These led to the design of machines, much larger. The largest operational ICF experiment is the National Ignition Facility in the US, like those earlier experiments, however, NIF has failed to reach ignition and is, as of 2015, generating about 1⁄3 of the required energy levels. This is a step forward. A similar large-scale device in France, Laser Mégajoule, was inaugurated in October 2014. Experiments have started since then, albeit with low laser energies involved, Fusion reactions combine lighter atoms, such as hydrogen, together to form larger ones. Nuclei are positively charged, and thus repel each other due to the electrostatic force, overcoming this repulsion costs a considerable amount of energy, which is known as the Coulomb barrier or fusion barrier energy. Generally, less energy will be needed to cause lighter nuclei to fuse, as they have less charge and thus a lower energy. The best fuel from a perspective is a one-to-one mix of deuterium and tritium. The D-T mix has a low barrier because of its high ratio of neutrons to protons, the presence of neutral neutrons in the nuclei helps pull them together via the nuclear force, while the presence of positively charged protons pushes the nuclei apart via electrostatic force. Tritium has one of the highest ratios of neutrons to protons of any stable or moderately unstable nuclide—two neutrons, adding protons or removing neutrons increases the energy barrier
Inertial confinement fusion
Inertial confinement fusion
–
Indirect drive laser ICF uses a "hohlraum" which is irradiated with laser beam cones from either side on its inner surface to bathe a fusion microcapsule inside with smooth high intensity X-rays. The highest energy X-rays can be seen leaking through the hohlraum, represented here in orange/red.
Inertial confinement fusion
–
An Inertial confinement fusion target, which was a cylindrical hohlraum target of D-T, being compressed by the Nova Laser. This shot was done in 1995. The image shows the compression of the target, as well as the growth of the Rayleigh-Taylor instabilities.
Inertial confinement fusion
–
Mockup of a gold plated
NIF hohlraum.
8.
Hinduism
–
Hinduism is a religion, or a way of life, found most notably in India and Nepal. Hinduism has been called the oldest religion in the world, and some practitioners and scholars refer to it as Sanātana Dharma, scholars regard Hinduism as a fusion or synthesis of various Indian cultures and traditions, with diverse roots and no founder. This Hindu synthesis started to develop between 500 BCE and 300 CE following the Vedic period, although Hinduism contains a broad range of philosophies, it is linked by shared concepts, recognisable rituals, cosmology, shared textual resources, and pilgrimage to sacred sites. Hindu texts are classified into Shruti and Smriti and these texts discuss theology, philosophy, mythology, Vedic yajna, Yoga, agamic rituals, and temple building, among other topics. Major scriptures include the Vedas and Upanishads, the Bhagavad Gita, prominent themes in Hindu beliefs include the four Puruṣārthas, the proper goals or aims of human life, namely Dharma, Artha, Kama and Moksha, karma, samsara, and the various Yogas. Hindu practices include such as puja and recitations, meditation, family-oriented rites of passage, annual festivals. Some Hindus leave their world and material possessions, then engage in lifelong Sannyasa to achieve Moksha. Hinduism prescribes the eternal duties, such as honesty, refraining from injuring living beings, patience, forbearance, self-restraint, Hinduism is the worlds third largest religion, with over one billion followers or 15% of the global population, known as Hindus. The majority of Hindus reside in India, Nepal, Mauritius, the Caribbean, the word Hindu is derived from the Indo-Aryan/Sanskrit word Sindhu, the Indo-Aryan name for the Indus River in the northwestern part of the Indian subcontinent. The term Hindu in these ancient records is a geographical term, the Arabic term al-Hind referred to the people who live across the River Indus. This Arabic term was taken from the pre-Islamic Persian term Hindū. By the 13th century, Hindustan emerged as an alternative name of India. It was only towards the end of the 18th century that European merchants and colonists began to refer to the followers of Indian religions collectively as Hindus. The term Hinduism, then spelled Hindooism, was introduced into the English language in the 18th-century to denote the religious, philosophical, because of the wide range of traditions and ideas covered by the term Hinduism, arriving at a comprehensive definition is difficult. The religion defies our desire to define and categorize it, Hinduism has been variously defined as a religion, a religious tradition, a set of religious beliefs, and a way of life. From a Western lexical standpoint, Hinduism like other faiths is appropriately referred to as a religion, in India the term dharma is preferred, which is broader than the western term religion. Hindu traditionalists prefer to call it Sanatana Dharma, the study of India and its cultures and religions, and the definition of Hinduism, has been shaped by the interests of colonialism and by Western notions of religion. Since the 1990s, those influences and its outcomes have been the topic of debate among scholars of Hinduism, Hinduism as it is commonly known can be subdivided into a number of major currents
Hinduism
–
Swami Vivekananda was a key figure in introducing
Vedanta and
Yoga in Europe and USA, raising interfaith awareness and making Hinduism a world religion.
Hinduism
–
Temple wall panel relief sculpture at the
Hoysaleswara temple in
Halebidu, representing the
Trimurti:
Brahma,
Shiva and
Vishnu.
Hinduism
–
The
Rigveda is the first and most important Veda and is one of the oldest
religious texts. This Rigveda
manuscript is in
Devanagari.
Hinduism
–
A wedding is the most extensive personal ritual an adult Hindu undertakes in his or her life. A typical
Hindu wedding is solemnized before Vedic
fire ritual (shown).
9.
Shiva
–
ShiVa3D is a 3D game engine with a graphical editor designed to create applications and video games for desktop PCs, the web, game consoles and mobile devices. Games made with ShiVa can be exported to over 20 target platforms, numerous applications have been created using ShiVa, including the Prince of Persia 2 remake for Mobiles and Babel Rising published by Ubisoft. With ShiVa 2.0, the version of the Editor is currently under heavy development. ShiVa Editor 1. x runs exclusively on Windows XP/Vista/7/8/8.1, ShiVa 1. x games are being built by the ShiVa Authoring Tool, a free companion product to the Editor, which transforms game packages into native applications. Since not all platforms have SDKs for Windows, the Authoring Tool is available for Mac OS X as well as Windows, ShiVa Editor 2. x runs natively on Windows XP/Vista/7/8/8.1 x86/x8664, Mac OS X x8664 and Linux x8664. ShiVa is proprietary software and licensed under the ShiVa EULA. Several license packages are available, ShiVa Web Edition is free to download, exports are watermarked except for the ShiVa Web Player browser plugin, Adobe Flash and HTML5/WebGL. ShiVa Basic Edition was built for indie developers and small development studios, beta versions may be downloaded and tested. C++ Plugins can be designed and tested, but not exported
Shiva
10.
Nova laser
–
Nova was a high-power laser built at the Lawrence Livermore National Laboratory in 1984 which conducted advanced inertial confinement fusion experiments until its dismantling in 1999. Nova was the first ICF experiment built with the intention of reaching ignition, Nova also generated considerable amounts of data on high-density matter physics, regardless of the lack of ignition, which is useful both in fusion power and nuclear weapons research. Inertial confinement fusion devices use drivers to rapidly heat the outer layers of a target in order to compress it, the target is a small spherical pellet containing a few milligrams of fusion fuel, typically a mix of deuterium and tritium. The heat of the laser burns the surface of the pellet into a plasma, the remaining portion of the target is driven inwards due to Newtons Third Law, eventually collapsing into a small point of very high density. The rapid blowoff also creates a wave that travels towards the center of the compressed fuel. When it reaches the center of the fuel and meets the shock from the side of the target. If the temperature and density of small spot can be raised high enough. The fusion reactions release high-energy particles, some of which collide with the high density fuel around it and this heats the fuel further, and can potentially cause that fuel to undergo fusion as well. This is a known as ignition, which can lead to a significant portion of the fuel in the target undergoing fusion. To date most ICF experiments have used lasers to heat the targets, calculations show that the energy must be delivered quickly in order to compress the core before it disassembles, as well as creating a suitable shock wave. The energy must also be focused extremely evenly across the outer surface in order to collapse the fuel into a symmetric core. Although other drivers have been suggested, notably heavy ions driven in particle accelerators, lasers are currently the only devices with the combination of features. Although this sounds very low powered compared to machines, at the time it was just beyond the state of the art. Prior to the construction of Nova, LLNL had designed and built a series of lasers that explored the problems of basic ICF design. LLNL was primarily interested in the Nd, glass laser, which, LLNL had decided early on to concentrate on glass lasers, while other facilities studied gas lasers using carbon dioxide or KrF. Building large Nd, glass lasers had not been attempted before, one problem was the homogeneity of the beams. Even minor variations in intensity of the beams would result in self-focusing in the air, the resulting beam included small filaments of extremely high light intensity, so high it would damage the glass optics of the device. This problem was solved in the Cyclops laser with the introduction of the spatial filtering technique, Cyclops was followed by the Argus laser of greater power, which explored the problems of controlling more than one beam and illuminating a target more evenly
Nova laser
–
View down Nova's laser bay between two banks of beamlines. The blue boxes contain the amplifiers and their flashtube "pumps", the tubes between the banks of amplifiers are the spatial filters.
Nova laser
–
Maintenance on the Nova target chamber. The various devices all point towards the center of the chamber where the targets are placed during experimental runs. The targets are held in place on the end of the white-colored "needle" at the end of the arm running vertically down into the chamber.
Nova laser
–
The Nova laser target chamber during alignment and initial installation (ca. early 1980s). Some of the larger diameter holes hold various measurement devices, which are designed to a standard size to fit into these ports while others are used as beam ports.
Nova laser
11.
Deuterium
–
Deuterium is one of two stable isotopes of hydrogen. The nucleus of deuterium, called a deuteron, contains one proton and one neutron, whereas the far more common hydrogen isotope, Deuterium has a natural abundance in Earths oceans of about one atom in 6420 of hydrogen. Thus deuterium accounts for approximately 0. 0156% of all the naturally occurring hydrogen in the oceans, the abundance of deuterium changes slightly from one kind of natural water to another. The deuterium isotopes name is formed from the Greek deuteros meaning second, Deuterium was discovered and named in 1931 by Harold Urey. When the neutron was discovered in 1932, this made the structure of deuterium obvious. Soon after deuteriums discovery, Urey and others produced samples of water in which the deuterium content had been highly concentrated. Deuterium is destroyed in the interiors of stars faster than it is produced, other natural processes are thought to produce only an insignificant amount of deuterium. Nearly all deuterium found in nature was produced in the Big Bang 13.8 billion years ago and this is the ratio found in the gas giant planets, such as Jupiter. However, other bodies are found to have different ratios of deuterium to hydrogen-1. This is thought to be as a result of natural isotope separation processes that occur from solar heating of ices in comets, like the water-cycle in Earths weather, such heating processes may enrich deuterium with respect to protium. The analysis of ratios in comets found results very similar to the mean ratio in Earths oceans. This reinforces theories that much of Earths ocean water is of cometary origin, the deuterium/protium ratio of the comet 67P/Churyumov-Gerasimenko, as measured by the Rosetta space probe, is about three times that of earth water. This figure is the highest yet measured in a comet, deuterium/protium ratios thus continue to be an active topic of research in both astronomy and climatology. Deuterium is frequently represented by the chemical symbol D, since it is an isotope of hydrogen with mass number 2, it is also represented by 2H. IUPAC allows both D and 2H, although 2H is preferred, a distinct chemical symbol is used for convenience because of the isotopes common use in various scientific processes. In quantum mechanics the energy levels of electrons in atoms depend on the mass of the system of electron. For hydrogen, this amount is about 1837/1836, or 1.000545, the energies of spectroscopic lines for deuterium and light-hydrogen therefore differ by the ratios of these two numbers, which is 1.000272. The wavelengths of all deuterium spectroscopic lines are shorter than the lines of light hydrogen
Deuterium
–
Deuterium discharge tube
Deuterium
–
Full table
Deuterium
–
Ionized deuterium in a
fusor reactor giving off its characteristic pinkish-red glow
Deuterium
–
Harold Urey
12.
Tritium
–
Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons, naturally occurring tritium is extremely rare on Earth, where trace amounts are formed by the interaction of the atmosphere with cosmic rays. It can be produced by irradiating lithium metal or lithium bearing ceramic pebbles in a nuclear reactor, the name of this isotope is derived from the Greek word τρίτος meaning third. While tritium has several different experimentally determined values of its half-life and it decays into helium-3 by beta decay as in this nuclear equation, and it releases 18.6 keV of energy in the process. The electrons kinetic energy varies, with an average of 5.7 keV, beta particles from tritium can penetrate only about 6.0 mm of air, and they are incapable of passing through the dead outermost layer of human skin. The unusually low energy released in the beta decay makes the decay appropriate for absolute neutrino mass measurements in the laboratory. The low energy of tritiums radiation makes it difficult to detect tritium-labeled compounds except by using liquid scintillation counting, Tritium is produced in nuclear reactors by neutron activation of lithium-6. This is possible with neutrons of any energy, and is an exothermic reaction yielding 4.8 MeV, in comparison, the fusion of deuterium with tritium releases about 17.6 MeV of energy. High-energy neutrons can produce tritium from lithium-7 in an endothermic reaction. This was discovered when the 1954 Castle Bravo nuclear test produced a high yield. High-energy neutrons irradiating boron-10 will also produce tritium, A more common result of boron-10 neutron capture is 7Li. The reactions requiring high neutron energies are not attractive production methods for peaceful applications, Tritium is also produced in heavy water-moderated reactors whenever a deuterium nucleus captures a neutron. This reaction has a quite small absorption cross section, making water a good neutron moderator. Even so, cleaning tritium from the moderator may be desirable after several years to reduce the risk of its escaping to the environment. Ontario Power Generations Tritium Removal Facility processes up to 2,500 tonnes of water a year. Deuteriums absorption cross section for thermal neutrons is about 0.52 millibarns, whereas that of oxygen-16 is about 0.19 millibarns and that of oxygen-17 is about 240 millibarns. Tritium is a product of the nuclear fission of uranium-235, plutonium-239. The release or recovery of tritium needs to be considered in the operation of reactors, especially in the reprocessing of nuclear fuels
Tritium
–
Radioluminescent 1.8
curies (67
GBq) 6 by 0.2 inches (152.4 mm × 5.1 mm) tritium vials are thin, tritium-gas-filled glass vials whose inner surfaces are coated with a
phosphor. The vial shown here is brand-new.
Tritium
–
Full table
Tritium
–
Swiss Military Watch Commander model with tritium-illuminated face
13.
Plasma (physics)
–
Plasma is one of the four fundamental states of matter, the others being solid, liquid, and gas. Yet unlike these three states of matter, plasma does not naturally exist on the Earth under normal surface conditions, the term was first introduced by chemist Irving Langmuir in the 1920s. However, true plasma production is from the separation of these ions and electrons that produces an electric field. Based on the environmental temperature and density either partially ionised or fully ionised forms of plasma may be produced. The positive charge in ions is achieved by stripping away electrons from atomic nuclei, the number of electrons removed is related to either the increase in temperature or the local density of other ionised matter. Plasma may be the most abundant form of matter in the universe, although this is currently tentative based on the existence. Plasma is mostly associated with the Sun and stars, extending to the rarefied intracluster medium, Plasma was first identified in a Crookes tube, and so described by Sir William Crookes in 1879. The nature of the Crookes tube cathode ray matter was identified by British physicist Sir J. J. The term plasma was coined by Irving Langmuir in 1928, perhaps because the glowing discharge molds itself to the shape of the Crookes tube and we shall use the name plasma to describe this region containing balanced charges of ions and electrons. Plasma is a neutral medium of unbound positive and negative particles. Although these particles are unbound, they are not ‘free’ in the sense of not experiencing forces, in turn this governs collective behavior with many degrees of variation. The average number of particles in the Debye sphere is given by the plasma parameter, bulk interactions, The Debye screening length is short compared to the physical size of the plasma. This criterion means that interactions in the bulk of the plasma are more important than those at its edges, when this criterion is satisfied, the plasma is quasineutral. Plasma frequency, The electron plasma frequency is compared to the electron-neutral collision frequency. When this condition is valid, electrostatic interactions dominate over the processes of ordinary gas kinetics, for plasma to exist, ionization is necessary. The term plasma density by itself refers to the electron density, that is. The degree of ionization of a plasma is the proportion of atoms that have lost or gained electrons, even a partially ionized gas in which as little as 1% of the particles are ionized can have the characteristics of a plasma. The degree of ionization, α, is defined as α = n i n i + n n, where n i is the number density of ions and n n is the number density of neutral atoms
Plasma (physics)
–
Plasma
Plasma (physics)
Plasma (physics)
Plasma (physics)
14.
Shock wave
–
In physics, a shock wave, or shock, is a type of propagating disturbance. When a wave moves faster than the speed of sound in a fluid it is a shock wave. In supersonic flows, expansion is achieved through an expansion fan also known as a Prandtl-Meyer expansion fan, unlike solitons, the energy of a shock wave dissipates relatively quickly with distance. Also, the accompanying expansion wave approaches and eventually merges with the shock wave, when a shock wave passes through matter, energy is preserved but entropy increases. Shock waves can be, Normal, at 90° to the shock mediums flow direction, oblique, at an angle to the direction of flow. Bow, Occurs upstream of the front of a blunt object when the flow velocity exceeds Mach 1. Some other terms Shock Front, The boundary over which the physical conditions undergo a change because of a shock wave. Contact Front, in a wave caused by a driver gas. The Contact Front trails the Shock Front, when an object moves faster than the information about it can propagate into the surrounding fluid, fluid near the disturbance cannot react or get out of the way before the disturbance arrives. In a shock wave the properties of the fluid change almost instantaneously, measurements of the thickness of shock waves in air have resulted in values around 200 nm, which is on the same order of magnitude as the mean free gas molecule path. In reference to the continuum, this implies the shock wave can be treated as either a line or a plane if the field is two-dimensional or three-dimensional. Shock waves are formed when a pressure front moves at supersonic speeds, Shock waves are not conventional sound waves, a shock wave takes the form of a very sharp change in the gas properties. Shock waves in air are heard as a crack or snap noise. Over longer distances, a wave can change from a nonlinear wave into a linear wave, degenerating into a conventional sound wave as it heats the air. The sound wave is heard as the familiar thud or thump of a sonic boom, the shock wave is one of several different ways in which a gas in a supersonic flow can be compressed. Some other methods are isentropic compressions, including Prandtl-Meyer compressions, the method of compression of a gas results in different temperatures and densities for a given pressure ratio which can be analytically calculated for a non-reacting gas. A shock wave compression results in a loss of pressure, meaning that it is a less efficient method of compressing gases for some purposes. The appearance of pressure-drag on supersonic aircraft is due to the effect of shock compression on the flow
Shock wave
–
Schlieren photograph of an attached shock on a sharp-nosed supersonic body.
Shock wave
–
Shock wave propagating into a stationary medium, ahead of the fireball of an explosion. The shock is made visible by the
shadow effect (Trinity explosion.)
Shock wave
–
Schlieren photograph of the detached shock on a bullet in supersonic flight, published by Ernst Mach and Peter Salcher in 1887.
Shock wave
–
Shadowgram of shock waves from a supersonic bullet fired from a rifle. The shadowgraph optical technique reveals that the bullet is moving at about a Mach number of 1.9. Left- and right-running bow waves and tail waves stream back from the bullet and its turbulent wake is also visible. Patterns at the far right are from unburned gunpowder particles ejected by the rifle.
15.
Cyclops laser
–
Cyclops was a high-power laser built at the Lawrence Livermore National Laboratory in 1975. It was the second constructed in the labs Laser program. The Cyclops was a single-beam Neodymium glass laser, the Janus laser, a two-beam version of it, was also completed in 1975. This novel problem only became obvious as the lasers were scaled up in power to where nonlinear phenomena occur with very intense beams of light, at the time there was no strong theoretical understanding of these effects, and predicting them was difficult. As Krupke noted, It was like the Rosetta stone, with this quantitative correspondence, they were able to plot the nonlinear refractive performance of millions of glasses and find the one with the lowest possible value. We then worked with our partners to make a composition with the characteristics we needed. Although using the glass was able to reduce the problem as much as possible. The simplest way to eliminate these effects was to them out physically using what essentially amounts to a Fourier transform technique applied to the beams spaitial intensity profile. Imaging spatial filters are, in effect, small inverted telescopes inserted in the beam to focus the light through a pinhole. Such a laser had not previously built, the earlier Janus laser. It was precisely the problems of building a laser that Cyclops was built to study. In this goal Cyclops was successful, and every major ICF effort since has used the spatial filtering technique, while Cyclops was still under construction, another LLNL laser was being built that also incorporated the spatial filtering technique, Argus. Argus passed its light through a series of amplifiers, with spatial filters between each stage and easily achieved terawatt beam powers
Cyclops laser
–
The single beam Cyclops laser at
LLNL around the time of its completion in 1975.
16.
Argus laser
–
Argus advanced the study of laser-target interaction and paved the way for the construction of its successor, the 20 beam Shiva laser. In order to improve the quality of the beams, LLNL had started experimenting with the use of spatial filters in the single-beam Cyclops laser. The basic idea was to extend the device into a very long beamline. The technique was so successful on Argus it was referred to as being the savior of laser ICF. After the success of Cyclops in beam smoothing, the step was to further increase the energy. Argus used a series of five groups of amplifiers and spatial filters arranged along the beamlines, each one boosting power until it reached a total of about 1 kilojoule and these intensities would have been impossible to achieve without the use of spatial filtering. It became the first laser to perform experiments using X-rays produced by irradiating a hohlraum, the reduced production of hard X-ray energy via the production of hot electrons while using frequency doubled and tripled laser light was first noticed on Argus. Argus was shut down and dismantled in September 1981, maximum fusion yield for target implosions on Argus was about 109 neutrons per shot
Argus laser
–
Argus laser overhead view. The target chamber area is at the far wall (upper left).
17.
Brewster angle
–
Brewsters angle is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. When unpolarized light is incident at this angle, the light that is reflected from the surface is therefore perfectly polarized and this special angle of incidence is named after the Scottish physicist Sir David Brewster. When light encounters a boundary between two media with different refractive indices, some of it is reflected as shown in the figure above. The fraction that is reflected is described by the Fresnel equations and this equation is known as Brewsters law, and the angle defined by it is Brewsters angle. The physical mechanism for this can be understood from the manner in which electric dipoles in the media respond to p-polarized light. One can imagine that light incident on the surface is absorbed, the polarization of freely propagating light is always perpendicular to the direction in which the light is travelling. The dipoles that produce the transmitted light oscillate in the direction of that light. These same oscillating dipoles also generate the reflected light, however, dipoles do not radiate any energy in the direction of the dipole moment. With simple geometry this condition can be expressed as θ1 + θ2 =90 ∘, solving for θB gives θ B = arctan. For a glass medium in air, Brewsters angle for light is approximately 56°, while for an air-water interface. Since the refractive index for a given medium changes depending on the wavelength of light, the phenomenon of light being polarized by reflection from a surface at a particular angle was first observed by Étienne-Louis Malus in 1808. He attempted to relate the polarizing angle to the index of the material. In 1815, Brewster experimented with higher-quality materials and showed that this angle was a function of the refractive index, the concept of a polarizing angle can be extended to the concept of a Brewster wavenumber to cover planar interfaces between two linear bianisotropic materials. In the case of reflection at Brewsters angle, the reflected and refracted rays are mutually perpendicular, for magnetic materials, Brewsters angle can exist for only one of the incident wave polarizations, as determined by the relative strengths of the dielectric permittivity and magnetic permeability. This has implications for the existence of generalized Brewster angles for dielectric metasurfaces, polarized sunglasses use the principle of Brewsters angle to reduce glare from the sun reflecting off horizontal surfaces such as water or road. In a large range of angles around Brewsters angle, the reflection of p-polarized light is lower than s-polarized light, thus, if the sun is low in the sky, reflected light is mostly s-polarized. Polarizing sunglasses use a material such as Polaroid sheets to block horizontally-polarized light. The effect is strongest with smooth surfaces such as water, but reflections from roads, photographers use the same principle to remove reflections from water so that they can photograph objects beneath the surface
Brewster angle
–
Photograph taken of a window with a camera polarizer filter rotated to two different angles. In the picture at left, the polarizer is aligned with the polarization angle of the window reflection. In the picture at right, the polarizer has been rotated 90° eliminating the heavily polarized reflected sunlight.
Brewster angle
–
An illustration of the polarization of light that is incident on an interface at Brewster's angle.
18.
Spatial filter
–
A spatial filter is an optical device which uses the principles of Fourier optics to alter the structure of a beam of light or other electromagnetic radiation, typically coherent laser light. Spatial filtering is used to clean up the output of lasers, removing aberrations in the beam due to imperfect, dirty, or damaged optics. This filtering can be applied to transmit a pure transverse mode from a multimode laser while blocking other modes emitted from the optical resonator, the term filtering indicates that the desirable structural features of the original source pass through the filter, while the undesirable features are blocked. Apparatus which follows the filter effectively sees a higher-quality but lower-powered image of the source, an example of the use of spatial filter can be seen in advanced setup of micro-Raman spectroscopy. In spatial filtering, a lens is used to focus the beam, because of diffraction, a beam that is not a perfect plane wave will not focus to a single spot, but rather will produce a pattern of light and dark regions in the focal plane. For example, an imperfect beam might form a bright spot surrounded by a series of concentric rings and it can be shown that this two-dimensional pattern is the two-dimensional Fourier transform of the initial beams transverse intensity distribution. In this context, the plane is often called the transform plane. Light in the center of the transform pattern corresponds to a perfect. Other light corresponds to structure in the beam, with light further from the central spot corresponding to structure with higher spatial frequency, a pattern with very fine details will produce light very far from the transform planes central spot. In the example above, the central spot and rings of light surrounding it are due to the structure resulting when the beam passed through a circular aperture. The spot is enlarged because the beam is limited by the aperture to a size. This pattern is called an Airy pattern, after its discoverer George Airy, by altering the distribution of light in the transform plane and using another lens to reform the collimated beam, the structure of the beam can be altered. The most common way of doing this is to place an aperture in the beam allows the desired light to pass. With good optics and a small pinhole, one could even approximate a plane wave. In practice, the diameter of the aperture is chosen based on the length of the lens, the diameter and quality of the input beam. If the hole is too small, the quality is greatly improved. If the hole is too large, the quality may not be improved as much as desired. The size of aperture that can be used depends on the size
Spatial filter
–
A computer-generated example of an
Airy disk, point-source diffraction pattern.
19.
Laser pumping
–
Laser pumping is the act of energy transfer from an external source into the gain medium of a laser. The energy is absorbed in the medium, producing excited states in its atoms, when the number of particles in one excited state exceeds the number of particles in the ground state or a less-excited state, population inversion is achieved. In this condition, the mechanism of stimulated emission can take place, the pump power must be higher than the lasing threshold of the laser. The pump energy is provided in the form of light or electric current. To use the lamps energy most efficiently, the lamps and lasing medium are contained in a cavity that will redirect most of the lamps energy into the rod or dye cell. In the most common configuration, the medium is in the form of a rod located at one focus of a mirrored cavity. The flashlamp is a located at the other focus of the ellipse. In other cases an absorber for the longer wavelengths is used, often, the lamp is surrounded by a cylindrical jacket called a flow tube. This flow tube is made of a glass that will absorb unsuitable wavelengths, such as ultraviolet. Often, the jacket is given a coating that reflects unsuitable wavelengths of light back into the lamp. This light is absorbed and some of it is re-emitted at suitable wavelengths, the flow tube also serves to protect the rod in the event of a violent lamp failure. Smaller ellipses create fewer reflections, giving higher intensity in the center of the rod. For a single flashlamp, if the lamp and rod are equal diameter, the rod and the lamp are relatively long to minimize the effect of losses at the end faces and to provide a sufficient length of gain medium. Longer flashlamps are also efficient at transferring electrical energy into light. However, if the rod is too long in relation to its diameter a condition called prelasing can occur, rod ends are often antireflection coated or cut at Brewsters angle to minimize this effect. Flat mirrors are often used at the ends of the pump cavity to reduce loss. Variations on this use more complex mirrors composed of overlapping elliptical shapes. This allows greater power, but are less efficient because not all of the light is correctly imaged into the rod and these losses can be minimized by using a close-coupled cavity
Laser pumping
–
A ruby laser head. The photo on the left shows the head unassembled, revealing the pumping cavity, the rod and the flashlamps. The photo on the right shows the head assembled.
Laser pumping
–
Various laser pumping cavity configurations.
Laser pumping
–
Laser pumping lamps. The top three are xenon flashlamps while the bottom one is a krypton arc lamp
Laser pumping
–
External triggering was used in this extremely fast discharge. Due to the very high speed, (3.5 microseconds), the current is not only unable to fully heat the xenon and fill the tube, but is still in direct contact with the glass.
20.
Xenon flash lamp
–
A flashtube, also called a flashlamp, is an electric arc lamp designed to produce extremely intense, incoherent, full-spectrum white light for very short durations. Flashtubes are made of a length of tubing with electrodes at either end and are filled with a gas that. Flashtubes are used mostly for photographic purposes but are employed in scientific, medical, industrial. The lamp comprises a hermetically sealed tube, which is filled with a noble gas, usually xenon. Additionally, a high power source is necessary to energize the gas as a trigger event. A charged capacitor is used to supply energy for the flash. In some applications, the emission of light is undesired, whether due to production of ozone, damage to laser rods, degradation of plastics. In these cases, a fused silica is used. A better alternative is a cerium-doped quartz, it does not suffer from solarization and has higher efficiency and its cutoff is at about 380 nm. The power level of the lamps is rated in watts/area, total electrical input power divided by the inner wall surface. Cooling of the electrodes and the envelope is of high importance at high power levels. Air cooling is sufficient for lower power levels. High power lamps are cooled with a liquid, typically by flowing demineralized water through a tube in which the lamp is encased, water-cooled lamps will generally have the glass shrunk around the electrodes, to provide a direct thermal conductor between them and the cooling water. The cooling medium should flow also across the length of the lamp. Above 15 W/cm2 forced air cooling is required, liquid cooling if in a confined space, liquid cooling is generally necessary above 30 W/cm2. For this reason, thinner glass is used for continuous-wave arc-lamps. Thicker materials can generally handle more impact energy from the wave that a short-pulsed arc can generate. The material of the envelope provides another limit for the power,1 mm thick fused quartz has a limit of 200 W/cm2
Xenon flash lamp
–
Helical xenon flashtube - Animated version below
Xenon flash lamp
–
Flashtubes of various sizes for laser pumping. The top three are xenon flashtubes. The last one is a krypton arc lamp, (shown for comparison).
Xenon flash lamp
–
Xenon flashtubes used on
smartphones and cameras are usually externally triggered.
Xenon flash lamp
–
A ruby laser head, assembled and disassembled, revealing pumping cavity, the ruby rod, and two water-cooled flashtubes.
21.
Capacitor
–
A capacitor is a passive two-terminal electrical component that stores electrical energy in an electric field. The effect of a capacitor is known as capacitance, a capacitor was therefore historically first known as an electric condenser. The physical form and construction of practical capacitors vary widely and many types are in common use. Most capacitors contain at least two electrical conductors often in the form of plates or surfaces separated by a dielectric medium. A conductor may be a foil, thin film, sintered bead of metal, the nonconducting dielectric acts to increase the capacitors charge capacity. Materials commonly used as dielectrics include glass, ceramic, plastic film, paper, mica, Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, a capacitor does not dissipate energy. No current actually flows through the dielectric, instead, the effect is a displacement of charges through the source circuit, if the condition is maintained sufficiently long, this displacement current through the battery ceases. However, if a voltage is applied across the leads of the capacitor. Capacitance is defined as the ratio of the charge on each conductor to the potential difference between them. The unit of capacitance in the International System of Units is the farad, capacitance values of typical capacitors for use in general electronics range from about 1 pF to about 1 mF. The capacitance of a capacitor is proportional to the area of the plates. In practice, the dielectric between the plates passes a small amount of leakage current and it has an electric field strength limit, known as the breakdown voltage. The conductors and leads introduce an undesired inductance and resistance, Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass. In analog filter networks, they smooth the output of power supplies, in resonant circuits they tune radios to particular frequencies. In electric power systems, they stabilize voltage and power flow. The property of energy storage in capacitors was exploited as dynamic memory in digital computers. Von Kleists hand and the water acted as conductors, and the jar as a dielectric, von Kleist found that touching the wire resulted in a powerful spark, much more painful than that obtained from an electrostatic machine
Capacitor
–
Capacitor
Capacitor
–
Miniature low-voltage capacitors (next to a cm ruler)
Capacitor
–
A typical
electrolytic capacitor
Capacitor
–
4 electrolytic capacitors of different voltages and capacitance
22.
Excited state
–
In quantum mechanics, an excited state of a system is any quantum state of the system that has a higher energy than the ground state. Excitation is an elevation in energy level above a baseline energy state. In physics there is a technical definition for energy level which is often associated with an atom being raised to an excited state. The temperature of a group of particles is indicative of the level of excitation and this return to a lower energy level is often loosely described as decay and is the inverse of excitation. Long-lived excited states are called metastable. Long-lived nuclear isomers and singlet oxygen are two examples of this, a simple example of this concept comes by considering the hydrogen atom. The ground state of the hydrogen atom corresponds to having the single electron in the lowest possible orbit. By giving the additional energy, the electron is able to move into an excited state. If the photon has too much energy, the electron will cease to be bound to the atom, after excitation the atom may return to the ground state or a lower excited state, by emitting a photon with a characteristic energy. Emission of photons from atoms in excited states leads to an electromagnetic spectrum showing a series of characteristic emission lines An atom in a high excited state is termed Rydberg atom. A system of highly excited atoms can form a long-lived condensed excited state e. g. a condensed phase made completely of excited atoms, hydrogen can also be excited by heat or electricity. This phenomenon has been studied in the case of a gas in some detail. These calculations are more difficult than non-excited state calculations, a further consequence is reaction of the atom in the excited state, as in photochemistry. Excited states give rise to chemical reaction, Rydberg formula Stationary state Repulsive state NASA background information on ground and excited states
Excited state
–
After absorbing energy, an electron may jump from the ground state to a higher energy excited state.
23.
Population inversion
–
It is called an inversion because in many familiar and commonly encountered physical systems, this is not possible. The concept is of importance in laser science because the production of a population inversion is a necessary step in the workings of a standard laser. To understand the concept of an inversion, it is necessary to understand some thermodynamics. To do so, it is useful to consider a simple assembly of atoms forming a laser medium. Assume there are a group of N atoms, each of which is capable of being in one of two states, either The ground state, with energy E1, or The excited state, with energy E2. The number of atoms which are in the ground state is given by N1. We may calculate the ratio of the populations of the two states at room temperature for an energy difference ΔE that corresponds to light of a frequency corresponding to visible light. In this case ΔE = E2 - E1 ≈2.07 eV, when in thermal equilibrium, then, it is seen that the lower energy state is more populated than the higher energy state, and this is the normal state of the system. In other words, an inversion can never exist for a system at thermal equilibrium. To achieve population inversion therefore requires pushing the system into a non-equilibrated state, the rate of absorption is proportional to the radiation intensity of the light, and also to the number of atoms currently in the ground state, N1. If atoms are in the state, spontaneous decay events to the ground state will occur at a rate proportional to N2. The energy difference between the two states ΔE21 is emitted from the atom as a photon of frequency ν21 as given by the relation above. The photons are emitted stochastically, and there is no fixed relationship between photons emitted from a group of excited atoms, in other words, spontaneous emission is incoherent. If an atom is already in the state, it may be perturbed by the passage of a photon that has a frequency ν21 corresponding to the energy gap ΔE of the excited state to ground state transition. In this case, the excited atom relaxes to the ground state, the original photon is not absorbed by the atom, and so the result is two photons of the same frequency. This process is known as stimulated emission, specifically, an excited atom will act like a small electric dipole which will oscillate with the external field provided. One of the consequences of this oscillation is that it encourages electrons to decay to the lowest energy state. When this happens due to the presence of the field from a photon, a photon is released in the same phase and direction as the stimulating photon
Population inversion
–
A three-level laser energy diagram.
24.
Stimulated emission
–
Stimulated emission is the process by which an incoming photon of a specific frequency can interact with an excited atomic electron, causing it to drop to a lower energy level. This is in contrast to spontaneous emission, which occurs at random intervals without regard to the ambient electromagnetic field. The process is identical in form to atomic absorption in which the energy of a photon causes an identical but opposite atomic transition. In normal media at thermal equilibrium, absorption exceeds stimulated emission because there are electrons in the lower energy states than in the higher energy states. However, when an inversion is present, the rate of stimulated emission exceeds that of absorption. Such a gain medium, along with a resonator, is at the heart of a laser or maser. Lacking a feedback mechanism, laser amplifiers and superluminescent sources also function on the basis of stimulated emission, electrons and their interactions with electromagnetic fields are important in our understanding of chemistry and physics. In the classical view, the energy of an electron orbiting a nucleus is larger for orbits further from the nucleus of an atom. However, quantum mechanical effects force electrons to take on positions in orbitals. Thus, electrons are found in energy levels of an atom, two of which are shown below, When an electron absorbs energy either from light or heat. But transitions are allowed between discrete energy levels such as the two shown above. This leads to lines and absorption lines. When an electron is excited from a lower to an energy level. An electron in a state may decay to a lower energy state which is not occupied. When such an electron decays without external influence, emitting a photon, the phase and direction associated with the photon that is emitted is random. This is the mechanism of fluorescence and thermal emission, an external electromagnetic field at a frequency associated with a transition can affect the quantum mechanical state of the atom without being absorbed. In response to the electric field at this frequency, the probability of the electrons entering this transition state is greatly increased. Thus, the rate of transitions between two states is increased beyond that of spontaneous emission
Stimulated emission
–
Contents
25.
Joules
–
The joule, symbol J, is a derived unit of energy in the International System of Units. It is equal to the transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre. It is also the energy dissipated as heat when a current of one ampere passes through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule, one joule can also be defined as, The work required to move an electric charge of one coulomb through an electrical potential difference of one volt, or one coulomb volt. This relationship can be used to define the volt, the work required to produce one watt of power for one second, or one watt second. This relationship can be used to define the watt and this SI unit is named after James Prescott Joule. As with every International System of Units unit named for a person, note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, section 5.2. The CGPM has given the unit of energy the name Joule, the use of newton metres for torque and joules for energy is helpful to avoid misunderstandings and miscommunications. The distinction may be also in the fact that energy is a scalar – the dot product of a vector force. By contrast, torque is a vector – the cross product of a distance vector, torque and energy are related to one another by the equation E = τ θ, where E is energy, τ is torque, and θ is the angle swept. Since radians are dimensionless, it follows that torque and energy have the same dimensions, one joule in everyday life represents approximately, The energy required to lift a medium-size tomato 1 m vertically from the surface of the Earth. The energy released when that same tomato falls back down to the ground, the energy required to accelerate a 1 kg mass at 1 m·s−2 through a 1 m distance in space. The heat required to raise the temperature of 1 g of water by 0.24 °C, the typical energy released as heat by a person at rest every 1/60 s. The kinetic energy of a 50 kg human moving very slowly, the kinetic energy of a 56 g tennis ball moving at 6 m/s. The kinetic energy of an object with mass 1 kg moving at √2 ≈1.4 m/s, the amount of electricity required to light a 1 W LED for 1 s. Since the joule is also a watt-second and the unit for electricity sales to homes is the kW·h. For additional examples, see, Orders of magnitude The zeptojoule is equal to one sextillionth of one joule,160 zeptojoules is equivalent to one electronvolt. The nanojoule is equal to one billionth of one joule, one nanojoule is about 1/160 of the kinetic energy of a flying mosquito
Joules
–
Base units
26.
Electron
–
The electron is a subatomic particle, symbol e− or β−, with a negative elementary electric charge. Electrons belong to the first generation of the lepton particle family, the electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the include a intrinsic angular momentum of a half-integer value, expressed in units of the reduced Planck constant. As it is a fermion, no two electrons can occupy the same state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of particles and waves, they can collide with other particles and can be diffracted like light. Since an electron has charge, it has an electric field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law, electrons radiate or absorb energy in the form of photons when they are accelerated. Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields, special telescopes can detect electron plasma in outer space. Electrons are involved in applications such as electronics, welding, cathode ray tubes, electron microscopes, radiation therapy, lasers, gaseous ionization detectors. Interactions involving electrons with other particles are of interest in fields such as chemistry. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms, ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the cause of chemical bonding. In 1838, British natural philosopher Richard Laming first hypothesized the concept of a quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge electron in 1891, electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of isotopes and in high-energy collisions. The antiparticle of the electron is called the positron, it is identical to the electron except that it carries electrical, when an electron collides with a positron, both particles can be totally annihilated, producing gamma ray photons. The ancient Greeks noticed that amber attracted small objects when rubbed with fur, along with lightning, this phenomenon is one of humanitys earliest recorded experiences with electricity. In his 1600 treatise De Magnete, the English scientist William Gilbert coined the New Latin term electricus, both electric and electricity are derived from the Latin ēlectrum, which came from the Greek word for amber, ἤλεκτρον
Electron
–
A beam of electrons deflected in a circle by a magnetic field
Electron
–
Hydrogen atom
orbitals at different energy levels. The brighter areas are where you are most likely to find an electron at any given time.
Electron
–
Robert Millikan
Electron
–
A
lightning discharge consists primarily of a flow of electrons. The electric potential needed for lightning may be generated by a triboelectric effect.
27.
Raman scattering
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Raman scattering or the Raman effect /ˈrɑːmən/ is the inelastic scattering of a photon by molecules which are excited to higher vibrational or rotational energy levels. It was discovered by C. V. Raman and K. S. Krishnan in liquids, the effect had been predicted theoretically by Adolf Smekal in 1923. When photons are scattered from an atom or molecule, most photons are elastically scattered, a small fraction of the scattered photons are scattered by an excitation, with the scattered photons having a frequency different from, and usually lower than, that of the incident photons. In a gas, Raman scattering can occur with a change in energy of a due to a transition to another energy level. Chemists are primarily concerned with the transitional Raman effect, the inelastic scattering of light was predicted by Adolf Smekal in 1923. In 1922, Indian physicist C. V, the Raman effect was first reported by C. V. Raman and K. S. Krishnan, and independently by Grigory Landsberg and Leonid Mandelstam, on 21 February 1928. Raman received the Nobel Prize in 1930 for his work on the scattering of light, for any given chemical compound, there are a total of 3N degrees of freedom, where N is the number of atoms in the compound. This number arises from the ability of each atom in a molecule to move in three different directions, when dealing with molecules, it is more common to consider the movement of the molecule as a whole. Consequently, the 3N degrees of freedom are partitioned into molecular translational, rotational, three of the degrees of freedom correspond to translational motion of the molecule as a whole. Similarly, three degrees of freedom correspond to rotations of the molecule about the x, y, and z -axes, linear molecules only have two rotations because rotations along the bond axis do not change the positions of the atoms in the molecule. The remaining degrees of freedom correspond to vibrational modes. These modes include stretching and bending motions of the bonds of the molecule. These frequencies correspond to radiation in the region of the electromagnetic spectrum. At any given instant, each molecule in a sample has an amount of vibrational energy. However, the amount of energy that a molecule has continually changes due to collisions. At room temperature, most of the molecules will be in the lowest energy state, a few molecules will be in higher energy states, which are known as excited states. The fraction of molecules occupying a given vibrational mode at a temperature can be calculated using the Boltzmann distribution. Performing such a calculation shows that, for low temperatures
Raman scattering
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Feynman diagram of scattering between two electrons by emission of a virtual
photon
28.
Ultraviolet
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Ultraviolet is an electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays. UV radiation constitutes about 10% of the light output of the Sun. It is also produced by electric arcs and specialized lights, such as lamps, tanning lamps. Consequently, the effects of UV are greater than simple heating effects. Suntan, freckling and sunburn are familiar effects of over-exposure, along with risk of skin cancer. Living things on dry land would be damaged by ultraviolet radiation from the Sun if most of it were not filtered out by the Earths atmosphere. More-energetic, shorter-wavelength extreme UV below 121 nm ionizes air so strongly that it is absorbed before it reaches the ground, Ultraviolet is also responsible for the formation of bone-strengthening vitamin D in most land vertebrates, including humans. The UV spectrum thus has both beneficial and harmful to human health. Ultraviolet rays are invisible to most humans, the lens in a human eye ordinarily filters out UVB frequencies or higher, and humans lack color receptor adaptations for ultraviolet rays. Under some conditions, children and young adults can see ultraviolet down to wavelengths of about 310 nm, near-UV radiation is visible to some insects, mammals, and birds. Small birds have a fourth color receptor for ultraviolet rays, this gives birds true UV vision, reindeer use near-UV radiation to see polar bears, who are poorly visible in regular light because they blend in with the snow. UV also allows mammals to see urine trails, which is helpful for animals to find food in the wild. The males and females of some species look identical to the human eye. Ultraviolet means beyond violet, violet being the color of the highest frequencies of visible light, Ultraviolet has a higher frequency than violet light. He called them oxidizing rays to emphasize chemical reactivity and to them from heat rays. The terms chemical and heat rays were eventually dropped in favour of ultraviolet and infrared radiation, in 1878 the effect of short-wavelength light on sterilizing bacteria was discovered. By 1903 it was known the most effective wavelengths were around 250 nm, in 1960, the effect of ultraviolet radiation on DNA was established. The discovery of the ultraviolet radiation below 200 nm, named vacuum ultraviolet because it is absorbed by air, was made in 1893 by the German physicist Victor Schumann
Ultraviolet
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(left) Portable ultraviolet lamp. (right) UV light is also produced by
electric arcs.
Arc welders must wear
eye protection to prevent
welder's flash.
Ultraviolet
Ultraviolet
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Two black light fluorescent tubes, showing use. The longer tube is a F15T8/BLB 18 inch, 15 watt tube, shown in the bottom image in a standard plug-in fluorescent fixture. The shorter is an F8T5/BLB 12 inch, 8 watt tube, used in a portable battery-powered black light sold as a pet urine detector.
Ultraviolet
29.
Laboratory for Laser Energetics
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The Laboratory for Laser Energetics is a scientific research facility which is part of the University of Rochesters south campus, located in Brighton, New York. The Laser Lab was commissioned to serve as a center for investigations of high-energy physics, the lab shares its building with the Center for Optoelectronics and Imaging and the Center for Optics Manufacturing. A new addition, the Robert L. Sproull Center for Ultra High Intensity Laser Research, was opened in 2005 and houses the OMEGA EP laser, the laboratory is unique in conducting big science on a university campus. More than 180 Phds have been award for research done at the LLE, during summer months the lab sponsors a program for high school students which involves local-area high school juniors in the research being done at the laboratory. Most of the projects are done on current research that is led by scientists at the lab. The LLE was founded on the University of Rochesters campus in 1970, working with outside companies such as Kodak the team built Delta, a four beam laser system in 1972. Construction started on the current LLE site in 1976, the facility opened in 1978 a six beam laser systems and a 24 beam system follows two years later. In 1985, Donna Strickland and Gérard Mourou invent a method to amplify lasers pulses by chirping and this method change a single wavelength of laser light into a spectrum of wavelengths. The system amplifies the laser at each wavelength and then reconstitutes the beam into one color, chirp pulsed amplification became instrumental in building the National Ignition Facility and the Omega EP system. In 1995, the laser was increased to 60 beams system. The OMEGA laser at the LLE is one of the most powerful and it is a 60-beam ultraviolet frequency-tripled neodymium glass laser, which is capable of delivering 30 kilojoules at up to 60 terawatts onto a target less than 2 millimeter in diameter. Construction and commissioning of the laser were completed in 1995, OMEGA held the record for highest energy laser from 1999 to 2005, when the first 8 beams of the National Ignition Facility exceeded OMEGAs output by about 30 kJ in the ultraviolet. The maximum fusion yield of OMEGA so far is about 1014 neutrons per shot, the four beam OMEGA EP laser system was dedicated on May 16,2008. The laser is housed inside the newest addition to the building, the combination of the OMEGA and the OMEGA EP laser systems will allow the LLE to be the worlds only facility capable of fully integrated cryogenic fast ignition experiments. LLE is located on and operated by the University of Rochester, Omega and Omega EP are user facilities, open for use by the entire scientific community. The Laboratory has a mission, To conduct implosion experiments. To develop new laser and materials technologies, to provide graduate and undergraduate education in electro-optics, high-power lasers, high-energy-density physics, plasma physics, and nuclear fusion technology. To operate the National Laser Users Facility, to conduct research and development in advanced technology related to high-energy-density phenomena
Laboratory for Laser Energetics
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Laboratory for Laser Energetics
