In nuclear fusion power research, a divertor is a device within a tokamak that allows the online removal of waste material from the plasma while the reactor is still operating. This allows control over the buildup of fusion products in the fuel, removes impurities in the plasma that have entered into it from the vessel lining; the divertor was introduced during the earliest studies of fusion power systems in the 1950s. It was realized early on that successful fusion would result in heavier ions being created and left in the fuel; these impurities were responsible for the loss of heat, caused other effects that made it more difficult to keep the reaction going. The divertor was proposed as a solution to this problem. Operating on the same principle as a mass spectrometer, the plasma passes through the divertor region where heavier ions are flung out of the fuel mass by centrifugal force, colliding with some sort of absorber material, depositing its energy as heat. Considered to be a device required for operational reactors, few early designs included a divertor.
When early long-shot reactors started to appear in the 1970s, a serious practical problem emerged. No matter how constrained, plasma continued to leak out of the main confinement area, striking the walls of the reactor core and causing all sorts of problems. A major concern was sputtering in reactors with higher power and particle flux density, which caused ions of the vacuum chamber's wall metal to flow into the fuel and to cool it. During the 1980s it became common for reactors to include a feature known as the limiter, a small piece of material that projects a short distance into the outer edge of the main plasma confinement area. Ions from the fuel that are travelling outwards strike the limiter, thereby protecting the walls of the chamber from this damage. However, the problems with material being deposited into the fuel remained; this led as a device for protecting the reactor itself. In these designs, magnets pull the lower edge of the plasma to create a small region where the outer edge of the plasma, the "Scrape-Off Layer", hits a limiter-like plate.
The divertor improves on the limiter in several ways, but because modern reactors try to create plasmas with D-shaped cross-sections so the lower edge of the D is a natural location for the divertor. In modern examples the plates are replaced by lithium metal, which better captures the ions and causes less cooling when it enters the plasma. In ITER and the latest configuration of Joint European Torus, the lowest region of the torus is configured as a divertor, while Alcator C-Mod was built with divertor channels at both top and bottom. A tokamak featuring a divertor is known as a divertor divertor configuration tokamak. In this configuration, the particles escape through a magnetic "gap", which allows the energy absorbing part of the divertor to be placed outside the plasma; the divertor configuration makes it easier to obtain a more stable H-mode of operation. The plasma facing material in the divertor faces different stresses compared to the majority of the first wall. Nuclear fission Snowflake and the multiple divertor concepts.
March 2016 Limiters Divertors
A nuclear reactor known as an atomic pile, is a device used to initiate and control a self-sustained nuclear chain reaction. Nuclear reactors are used at nuclear power plants for electricity generation and in propulsion of ships. Heat from nuclear fission is passed to a working fluid; these either turn electrical generators' shafts. Nuclear generated steam in principle can be used for industrial process heat or for district heating; some reactors are used to produce isotopes for medical and industrial use, or for production of weapons-grade plutonium. Some are run only for research; as of early 2019, the IAEA reports there are 454 nuclear power reactors and 226 nuclear research reactors in operation around the world. Just as conventional power-stations generate electricity by harnessing the thermal energy released from burning fossil fuels, nuclear reactors convert the energy released by controlled nuclear fission into thermal energy for further conversion to mechanical or electrical forms; when a large fissile atomic nucleus such as uranium-235 or plutonium-239 absorbs a neutron, it may undergo nuclear fission.
The heavy nucleus splits into two or more lighter nuclei, releasing kinetic energy, gamma radiation, free neutrons. A portion of these neutrons may be absorbed by other fissile atoms and trigger further fission events, which release more neutrons, so on; this is known as a nuclear chain reaction. To control such a nuclear chain reaction, neutron poisons and neutron moderators can change the portion of neutrons that will go on to cause more fission. Nuclear reactors have automatic and manual systems to shut the fission reaction down if monitoring detects unsafe conditions. Used moderators include regular water, solid graphite and heavy water; some experimental types of reactor have used beryllium, hydrocarbons have been suggested as another possibility. The reactor core generates heat in a number of ways: The kinetic energy of fission products is converted to thermal energy when these nuclei collide with nearby atoms; the reactor absorbs some of the gamma rays produced during fission and converts their energy into heat.
Heat is produced by the radioactive decay of fission products and materials that have been activated by neutron absorption. This decay heat-source will remain for some time after the reactor is shut down. A kilogram of uranium-235 converted via nuclear processes releases three million times more energy than a kilogram of coal burned conventionally. A nuclear reactor coolant — water but sometimes a gas or a liquid metal or molten salt — is circulated past the reactor core to absorb the heat that it generates; the heat is carried away from the reactor and is used to generate steam. Most reactor systems employ a cooling system, physically separated from the water that will be boiled to produce pressurized steam for the turbines, like the pressurized water reactor. However, in some reactors the water for the steam turbines is boiled directly by the reactor core; the rate of fission reactions within a reactor core can be adjusted by controlling the quantity of neutrons that are able to induce further fission events.
Nuclear reactors employ several methods of neutron control to adjust the reactor's power output. Some of these methods arising from the physics of radioactive decay and are accounted for during the reactor's operation, while others are mechanisms engineered into the reactor design for a distinct purpose; the fastest method for adjusting levels of fission-inducing neutrons in a reactor is via movement of the control rods. Control rods therefore tend to absorb neutrons; when a control rod is inserted deeper into the reactor, it absorbs more neutrons than the material it displaces—often the moderator. This action results in fewer neutrons available to cause fission and reduces the reactor's power output. Conversely, extracting the control rod will result in an increase in the rate of fission events and an increase in power; the physics of radioactive decay affects neutron populations in a reactor. One such process is delayed neutron emission by a number of neutron-rich fission isotopes; these delayed neutrons account for about 0.65% of the total neutrons produced in fission, with the remainder released upon fission.
The fission products which produce delayed neutrons have half lives for their decay by neutron emission that range from milliseconds to as long as several minutes, so considerable time is required to determine when a reactor reaches the critical point. Keeping the reactor in the zone of chain-reactivity where delayed neutrons are necessary to achieve a critical mass state allows mechanical devices or human operators to control a chain reaction in "real time"; this last stage, where delayed neutrons are no longer required to maintain criticality, is known as the prompt critical point. There is a scale for describing criticality in numerical form, in which bare criticality is known as zero dollars and the prompt critical point is one dollar, other points in the process interpolated in cents. In some reactors, the coolant acts as a neutron moderator. A moderator increases the power of the reactor by causin
ITER is an international nuclear fusion research and engineering megaproject, which will be the world's largest magnetic confinement plasma physics experiment. It is an experimental tokamak nuclear fusion reactor, being built next to the Cadarache facility in Saint-Paul-lès-Durance, in Provence, southern France. ITER was proposed in 1987 and designed as the International Thermonuclear Experimental Reactor, according to the "ITER Technical Basis," published by the International Atomic Energy Agency, in 2002. By 2005, the ITER organization abandoned the original meaning of the acronym iter, instead adopted a new meaning, the Latin word for "the way."The ITER thermonuclear fusion reactor has been designed to produce a fusion plasma equivalent to 500 megawatts of thermal output power for around twenty minutes while 50 megawatts of thermal power are injected into the tokamak, resulting in a ten-fold gain of plasma heating power. Thereby the machine aims to demonstrate the principle of producing more thermal power from the fusion process than is used to heat the plasma, something that has not yet been achieved in any fusion reactor.
The total electricity consumed by the reactor and facilities will range from 110 MW up to 620 MW peak for 30-second periods during plasma operation. Thermal-to-electric conversion is not included in the design because ITER will not produce sufficient power for net electrical production; the emitted heat from the fusion reaction will be vented to the atmosphere. The project is funded and run by seven member entities—the European Union, Japan, Russia, South Korea, the United States; the EU, as host party for the ITER complex, is contributing about 45 percent of the cost, with the other six parties contributing 9 percent each. In 2016 the ITER organization signed a technical cooperation agreement with the national nuclear fusion agency of Australia, enabling this country access to research results of ITER in exchange for construction of selected parts of the ITER machine. Construction of the ITER Tokamak complex started in 2013 and the building costs are now over US$14 billion as of June 2015; the facility is expected to finish its construction phase in 2025 and will start commissioning the reactor that same year.
Initial plasma experiments are scheduled to begin in 2025, with full deuterium–tritium fusion experiments starting in 2035. If ITER becomes operational, it will become the largest magnetic confinement plasma physics experiment in use with a plasma volume of 840 cubic meters, surpassing the Joint European Torus by a factor of 10; the goal of ITER is to demonstrate the scientific and technological feasibility of fusion energy for peaceful use. It is the largest of more than 100 fusion reactors built since the 1950s. ITER's planned successor, DEMO, is expected to be the first fusion reactor to produce electricity in an experimental environment. DEMO's anticipated success is expected to lead to full-scale electricity-producing fusion power stations and future commercial reactors. Fusion power has the potential to provide sufficient energy to satisfy mounting demand, to do so sustainably, with a small impact on the environment. Nuclear fusion has many potential attractions. Firstly, its hydrogen isotope fuels are abundant – one of the necessary isotopes, can be extracted from seawater, while the other fuel, would be bred from a lithium blanket using neutrons produced in the fusion reaction itself.
Furthermore, a fusion reactor would produce no CO2 or atmospheric pollutants, its radioactive waste products would be short-lived compared to those produced by conventional nuclear reactors. On 21 November 2006, the seven participants formally agreed to fund the creation of a nuclear fusion reactor; the program is anticipated to last for 30 years – 10 for construction, 20 of operation. ITER was expected to cost €5 billion, but the rising price of raw materials and changes to the initial design have seen that amount triple to €13 billion; the reactor is expected to take 10 years to build with completion scheduled for 2019. Site preparation has begun in Cadarache and procurement of large components has started; when supplied with 300 MW of electrical power, ITER is expected to produce the equivalent of 500 MW of thermal power sustained for up to 1,000 seconds. This compares to JET's consumption of 700 MW of electrical power and peak thermal output of 16 MW for less than a second) by the fusion of about 0.5 g of deuterium/tritium mixture in its 840 m3 reactor chamber.
The heat produced in ITER will not be used to generate any electricity because after accounting for losses and the 300 MW minimum power input, the output will be equivalent to a zero power reactor. ITER began in 1985 as a Reagan–Gorbachev initiative with the equal participation of the Soviet Union, the European Atomic Energy Community, the United States, Japan through the 1988–1998 initial design phases. Preparations for the first Gorbachev-Reagan Summit showed that there were no tangible agreements in the works for the summit. One energy research project, was being considered by two physicists, Alvin Trivelpiece and Evgeny Velikhov; the project involved collaboration on the next phase of magnetic fusion research — the construction of a demonstration model. At the time, magnetic fusion research was ongoing in Japan, the Soviet Union and the US. Velikhov and Trivelpiece believed that taking the next step in fusion research would be beyond the budget of any of the key nations and that collaboration would be useful internationally.
A major bureaucratic fight erupted in the US government over the project. One argument against collabora
The ampere shortened to "amp", is the base unit of electric current in the International System of Units. It is named after André-Marie Ampère, French mathematician and physicist, considered the father of electrodynamics; the International System of Units defines the ampere in terms of other base units by measuring the electromagnetic force between electrical conductors carrying electric current. The earlier CGS measurement system had two different definitions of current, one the same as the SI's and the other using electric charge as the base unit, with the unit of charge defined by measuring the force between two charged metal plates; the ampere was defined as one coulomb of charge per second. In SI, the unit of charge, the coulomb, is defined as the charge carried by one ampere during one second. New definitions, in terms of invariant constants of nature the elementary charge, will take effect on 20 May 2019. SI defines ampere as follows: The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, placed one metre apart in vacuum, would produce between these conductors a force equal to 2×10−7 newtons per metre of length.
Ampère's force law states that there is an attractive or repulsive force between two parallel wires carrying an electric current. This force is used in the formal definition of the ampere; the SI unit of charge, the coulomb, "is the quantity of electricity carried in 1 second by a current of 1 ampere". Conversely, a current of one ampere is one coulomb of charge going past a given point per second: 1 A = 1 C s. In general, charge Q is determined by steady current I flowing. Constant and average current are expressed in amperes and the charge accumulated, or passed through a circuit over a period of time is expressed in coulombs; the relation of the ampere to the coulomb is the same as that of the watt to the joule. The ampere was defined as one tenth of the unit of electric current in the centimetre–gram–second system of units; that unit, now known as the abampere, was defined as the amount of current that generates a force of two dynes per centimetre of length between two wires one centimetre apart.
The size of the unit was chosen so that the units derived from it in the MKSA system would be conveniently sized. The "international ampere" was an early realization of the ampere, defined as the current that would deposit 0.001118 grams of silver per second from a silver nitrate solution. More accurate measurements revealed that this current is 0.99985 A. Since power is defined as the product of current and voltage, the ampere can alternatively be expressed in terms of the other units using the relationship I=P/V, thus 1 ampere equals 1 W/V. Current can be measured by a multimeter, a device that can measure electrical voltage and resistance; the standard ampere is most realized using a Kibble balance, but is in practice maintained via Ohm's law from the units of electromotive force and resistance, the volt and the ohm, since the latter two can be tied to physical phenomena that are easy to reproduce, the Josephson junction and the quantum Hall effect, respectively. At present, techniques to establish the realization of an ampere have a relative uncertainty of a few parts in 107, involve realizations of the watt, the ohm and the volt.
Rather than a definition in terms of the force between two current-carrying wires, it has been proposed that the ampere should be defined in terms of the rate of flow of elementary charges. Since a coulomb is equal to 6.2415093×1018 elementary charges, one ampere is equivalent to 6.2415093×1018 elementary charges moving past a boundary in one second. The proposed change would define 1 A as being the current in the direction of flow of a particular number of elementary charges per second. In 2005, the International Committee for Weights and Measures agreed to study the proposed change; the new definition was discussed at the 25th General Conference on Weights and Measures in 2014 but for the time being was not adopted. The current drawn by typical constant-voltage energy distribution systems is dictated by the power consumed by the system and the operating voltage. For this reason the examples given below are grouped by voltage level. Current notebook CPUs: up to 15...45 A Current high-end CPUs: up to 55...120 A Hearing aid: 700 µA USB charging adapter: 2 A A typical motor vehicle has a 12 V battery.
The various accessories that are powered by the battery might include: Instrument panel light: 166 mA Headlight: 5 A Starter motor on a smaller car: 50 A to 200 A Most Canada and United States domestic power suppliers run at 120 V. Household circuit breakers provide a maximum of 15 A or 20 A of current to a given set of outlets. USB charging adapter: 83 mA 22-inch/56-centimeter portable television: 290 mA Tungsten light bulb: 500–830 mA Toaster, kettle: 12.5 A Hair dryer: 15 A Most European domestic power supplies run at 230 V, most Commonwealth domestic power supplies run at 2
Nuclear power is the use of nuclear reactions that release nuclear energy to generate heat, which most is used in steam turbines to produce electricity in a nuclear power plant. As a nuclear technology, nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by nuclear fission of uranium and plutonium. Nuclear decay processes are used in niche applications such as radioisotope thermoelectric generators. Generating electricity from fusion power remains at the focus of international research; this article deals with nuclear fission power for electricity generation. Civilian nuclear power supplied 2,488 terawatt hours of electricity in 2017, equivalent to about 10% of global electricity generation; as of April 2018, there are 449 civilian fission reactors in the world, with a combined electrical capacity of 394 gigawatt. As of 2018, there are 58 power reactors under construction and 154 reactors planned, with a combined capacity of 63 GW and 157 GW, respectively.
As of January 2019, 337 more reactors were proposed. Most reactors under construction are generation III reactors in Asia. Nuclear power is classified as a low greenhouse gas energy supply technology, along with renewable energy, by the Intergovernmental Panel on Climate Change. Since its commercialization in the 1970s, nuclear power has prevented about 1.84 million air pollution-related deaths and the emission of about 64 billion tonnes of carbon dioxide equivalent that would have otherwise resulted from the burning of fossil fuels. There is a debate about nuclear power. Proponents, such as the World Nuclear Association and Environmentalists for Nuclear Energy, contend that nuclear power is a safe, sustainable energy source that reduces carbon emissions. Opponents, such as Greenpeace and NIRS, contend that nuclear power poses many threats to people and the environment. Accidents in nuclear power plants include the Chernobyl disaster in the Soviet Union in 1986, the Fukushima Daiichi nuclear disaster in Japan in 2011, the more contained Three Mile Island accident in the United States in 1979.
There have been some nuclear submarine accidents. Nuclear reactors have caused the lowest number of fatalities per unit of energy generated when compared to fossil fuels and hydropower. Coal, natural gas and hydroelectricity each have caused a greater number of fatalities per unit of energy, due to air pollution and accidents. Collaboration on research and development towards greater efficiency and recycling of spent fuel in future generation IV reactors presently includes Euratom and the co-operation of more than 10 permanent member countries globally. In 1932 physicist Ernest Rutherford discovered that when lithium atoms were "split" by protons from a proton accelerator, immense amounts of energy were released in accordance with the principle of mass–energy equivalence. However, he and other nuclear physics pioneers Niels Bohr and Albert Einstein believed harnessing the power of the atom for practical purposes anytime in the near future was unlikely; the same year, his doctoral student James Chadwick discovered the neutron, recognized as a potential tool for nuclear experimentation because of its lack of an electric charge.
Experiments bombarding materials with neutrons led Frédéric and Irène Joliot-Curie to discover induced radioactivity in 1934, which allowed the creation of radium-like elements. Further work by Enrico Fermi in the 1930s focused on using slow neutrons to increase the effectiveness of induced radioactivity. Experiments bombarding uranium with neutrons led Fermi to believe he had created a new, transuranic element, dubbed hesperium. In 1938, German chemists Otto Hahn and Fritz Strassmann, along with Austrian physicist Lise Meitner and Meitner's nephew, Otto Robert Frisch, conducted experiments with the products of neutron-bombarded uranium, as a means of further investigating Fermi's claims, they determined that the tiny neutron split the nucleus of the massive uranium atoms into two equal pieces, contradicting Fermi. This was an surprising result: all other forms of nuclear decay involved only small changes to the mass of the nucleus, whereas this process—dubbed "fission" as a reference to biology—involved a complete rupture of the nucleus.
Numerous scientists, including Leó Szilárd, one of the first, recognized that if fission reactions released additional neutrons, a self-sustaining nuclear chain reaction could result. Once this was experimentally confirmed and announced by Frédéric Joliot-Curie in 1939, scientists in many countries petitioned their governments for support of nuclear fission research, just on the cusp of World War II, for the development of a nuclear weapon. In the United States, where Fermi and Szilárd had both emigrated, the discovery of the nuclear chain reaction led to the creation of the first man-made reactor, the research reactor known as Chicago Pile-1, which achieved self-sustaining power/criticality on December 2, 1942; the reactor's development was part of the Manhattan Project, the Allied effort to create atomic bombs during World War II. It led to the building of larger single-purpose production reactors, such as the X-10 Pile, for the production of weapons-grade plutonium for use in the first nuclear weapons.
The United States tested the first nuclear weapon in July 1945, the Trinity test, with the atomic bombings of Hiroshima and Nagasaki taking place one month later. In August 1945, the first distributed account of nuclear energy, in the form of the pocketbook The Atomic Age, discussed the peaceful future uses of nuclear energy and depicted a future where fo
A ball-pen probe is a modified Langmuir probe used to measure the plasma potential in magnetized plasmas. The ball-pen probe balances the electron and ion saturation currents, so that its floating potential is equal to the plasma potential; because electrons have a much smaller gyroradius than ions, a moving ceramic shield can be used to screen off an adjustable part of the electron current from the probe collector. Ball-pen probes are used in plasma physics, notably in tokamaks such as CASTOR, ASDEX Upgrade, COMPASS, ISTTOK, MAST, TJ-K, RFX, H-1 Heliac, IR-T1, GOLEM as well as low temperature devices as DC cylindrical magnetron in Prague and linear magnetized plasma devices in Nancy and Ljubljana. If a Langmuir probe is inserted into a plasma, its potential is not equal to the plasma potential Φ because a Debye sheath forms, but instead to a floating potential V f l; the difference with the plasma potential is given by the electron temperature T e: Φ − V f l = α ∗ T e where the coefficient α is given by the ratio of the electron and ion saturation current density and collecting areas for electrons and ions: α = l n = l n The ball-pen probe modifies the collecting areas for electrons and ions in such a way that the ratio R is equal to one.
Α = 0 and the floating potential of the ball-pen probe becomes equal to the plasma potential regardless of the electron temperature: V f l = Φ A ball-pen probe consists of a conically shaped collector, shielded by an insulating tube. The collector is shielded and the whole probe head is placed perpendicular to magnetic field lines; when the collector slides within the shield, the ratio R varies, can be set to 1. The adequate retraction length depends on the magnetic field's value; the collector retraction should be below the ion's Larmor radius. Calibrating the proper position of the collector can be done in two different ways: The ball-pen probe collector is biased by a low-frequency voltage that provides the I-V characteristics and obtain the saturation current of electrons and ions; the collector is retracted until the I-V characteristics becomes symmetric. In this case, the ratio R is close to unity. If the probe is retracted deeper, the I-V characteristics remain symmetric; the ball-pen probe collector potential is left floating, the collector is retracted until its potential saturates.
The resulting potential is above the Langmuir probe potential. Using two measurements of the plasma potential with probes whose coefficient α differ, it is possible to retrieve the electron temperature passively. Using a Langmuir probe and a ball-point probe the electron temperature is given by: T e = Φ − V f l α where Φ is measured by the ball-pen probe, V f l by the standard Langmuir probe, α is given by the Langmuir probe geometry, plasma gas composition, the magnetic field, other minor factors It can be calculated theoretically, its value being about 3 for a non-magnetized hydrogen plasma. In practice, the ratio R for the ball-pen probe is not equal to one, so that the coefficient α must be corrected by an empirical value for R: T e = Φ B P P − V f l α ¯, where α ¯ = α − l n. PhD thesis, Jiri Adamek Overview: Ball-pen probe design, theory and fi
Germany the Federal Republic of Germany, is a country in Central and Western Europe, lying between the Baltic and North Seas to the north, the Alps to the south. It borders Denmark to the north and the Czech Republic to the east and Switzerland to the south, France to the southwest, Luxembourg and the Netherlands to the west. Germany includes 16 constituent states, covers an area of 357,386 square kilometres, has a temperate seasonal climate. With 83 million inhabitants, it is the second most populous state of Europe after Russia, the most populous state lying in Europe, as well as the most populous member state of the European Union. Germany is a decentralized country, its capital and largest metropolis is Berlin, while Frankfurt serves as its financial capital and has the country's busiest airport. Germany's largest urban area is the Ruhr, with its main centres of Essen; the country's other major cities are Hamburg, Cologne, Stuttgart, Düsseldorf, Dresden, Bremen and Nuremberg. Various Germanic tribes have inhabited the northern parts of modern Germany since classical antiquity.
A region named Germania was documented before 100 AD. During the Migration Period, the Germanic tribes expanded southward. Beginning in the 10th century, German territories formed a central part of the Holy Roman Empire. During the 16th century, northern German regions became the centre of the Protestant Reformation. After the collapse of the Holy Roman Empire, the German Confederation was formed in 1815; the German revolutions of 1848–49 resulted in the Frankfurt Parliament establishing major democratic rights. In 1871, Germany became a nation state when most of the German states unified into the Prussian-dominated German Empire. After World War I and the revolution of 1918–19, the Empire was replaced by the parliamentary Weimar Republic; the Nazi seizure of power in 1933 led to the establishment of a dictatorship, the annexation of Austria, World War II, the Holocaust. After the end of World War II in Europe and a period of Allied occupation, Austria was re-established as an independent country and two new German states were founded: West Germany, formed from the American and French occupation zones, East Germany, formed from the Soviet occupation zone.
Following the Revolutions of 1989 that ended communist rule in Central and Eastern Europe, the country was reunified on 3 October 1990. Today, the sovereign state of Germany is a federal parliamentary republic led by a chancellor, it is a great power with a strong economy. As a global leader in several industrial and technological sectors, it is both the world's third-largest exporter and importer of goods; as a developed country with a high standard of living, it upholds a social security and universal health care system, environmental protection, a tuition-free university education. The Federal Republic of Germany was a founding member of the European Economic Community in 1957 and the European Union in 1993, it is part of the Schengen Area and became a co-founder of the Eurozone in 1999. Germany is a member of the United Nations, NATO, the G7, the G20, the OECD. Known for its rich cultural history, Germany has been continuously the home of influential and successful artists, musicians, film people, entrepreneurs, scientists and inventors.
Germany has a large number of World Heritage sites and is among the top tourism destinations in the world. The English word Germany derives from the Latin Germania, which came into use after Julius Caesar adopted it for the peoples east of the Rhine; the German term Deutschland diutisciu land is derived from deutsch, descended from Old High German diutisc "popular" used to distinguish the language of the common people from Latin and its Romance descendants. This in turn descends from Proto-Germanic *þiudiskaz "popular", derived from *þeudō, descended from Proto-Indo-European *tewtéh₂- "people", from which the word Teutons originates; the discovery of the Mauer 1 mandible shows that ancient humans were present in Germany at least 600,000 years ago. The oldest complete hunting weapons found anywhere in the world were discovered in a coal mine in Schöningen between 1994 and 1998 where eight 380,000-year-old wooden javelins of 1.82 to 2.25 m length were unearthed. The Neander Valley was the location where the first non-modern human fossil was discovered.
The Neanderthal 1 fossils are known to be 40,000 years old. Evidence of modern humans dated, has been found in caves in the Swabian Jura near Ulm; the finds included 42,000-year-old bird bone and mammoth ivory flutes which are the oldest musical instruments found, the 40,000-year-old Ice Age Lion Man, the oldest uncontested figurative art discovered, the 35,000-year-old Venus of Hohle Fels, the oldest uncontested human figurative art discovered. The Nebra sky disk is a bronze artefact created during the European Bronze Age attributed to a site near Nebra, Saxony-Anhalt, it is part of UNESCO's Memory of the World Programme. The Germanic tribes are thought to date from the Pre-Roman Iron Age. From southern Scandinavia and north Germany, they expanded south and west from the 1st century BC, coming into contact with the Celtic tribes of Gaul as well