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91-417: The purpose of NSTAR program was to develop a xenon -fueled ion propulsion system for deep space missions. The NSTAR electrostatic ion thruster was developed at NASA's Glenn Research Center and manufactured by Hughes, and Spectrum Astro, Inc. in the early 1990s. The feed system development was a collaborative effort between JPL and Moog Inc . The ions are accelerated through two fine grids with roughly

182-467: A Xe nucleus has a spin of 1/2, and therefore a zero electric quadrupole moment , the Xe nucleus does not experience any quadrupolar interactions during collisions with other atoms, and the hyperpolarization persists for long periods even after the engendering light and vapor have been removed. Spin polarization of Xe can persist from several seconds for xenon atoms dissolved in blood to several hours in

273-430: A gas , liquid , plasma , or a solid . In powered aircraft without propellers such as jets , the propellant is usually the product of the burning of fuel with atmospheric oxygen so that the resulting propellant product has more mass than the fuel carried on the vehicle. Proposed photon rockets would use the relativistic momentum of photons to create thrust. Even though photons do not have mass, they can still act as

364-410: A nozzle . The exhaust material may be a gas , liquid , plasma , or a solid . In powered aircraft without propellers such as jets , the propellant is usually the product of the burning of fuel with atmospheric oxygen so that the resulting propellant product has more mass than the fuel carried on the vehicle. The propellant or fuel may also simply be a compressed fluid, with the potential energy that

455-465: A plasma which is used as the propellant. They use a nozzle to direct the energized propellant. The nozzle itself may be composed simply of a magnetic field. Low molecular weight gases (e.g. hydrogen, helium, ammonia) are preferred propellants for this kind of system. Electromagnetic thrusters use ions as the propellant, which are accelerated by the Lorentz force or by magnetic fields, either of which

546-498: A propellant for ion thrusters in spacecraft. Naturally occurring xenon consists of seven stable isotopes and two long-lived radioactive isotopes. More than 40 unstable xenon isotopes undergo radioactive decay , and the isotope ratios of xenon are an important tool for studying the early history of the Solar System . Radioactive xenon-135 is produced by beta decay from iodine-135 (a product of nuclear fission ), and

637-428: A 1300 V difference between them for 2.3 kW operation, with a thrust of 20-92  mN , a specific impulse of 19000-30500 N·s/kg (1950-3100 s) and a total impulse capability of 2.65 x10 Ns on DS1. In 1996, the prototype engine endured 8000 hours of continuous operation in a vacuum chamber that simulates conditions of outer space . The results of the prototyping were used to define the design of flight hardware that

728-451: A band of emission lines that span the visual spectrum, but the most intense lines occur in the region of blue light, producing the coloration. Xenon is a trace gas in Earth's atmosphere , occurring at a volume fraction of 87 ± 1 nL/L ( parts per billion ), or approximately 1 part per 11.5 million. It is also found as a component of gases emitted from some mineral springs . Given

819-483: A broad variety of payloads. Aerosol sprays , in which a liquid is ejected as a spray, include paints, lubricants, degreasers, and protective coatings; deodorants and other personal care products; cooking oils. Some liquid payloads are not sprayed due to lower propellant pressure and/or viscous payload, as with whipped cream and shaving cream or shaving gel. Low-power guns, such as BB guns , paintball guns, and airsoft guns, have solid projectile payloads. Uniquely, in

910-400: A compressor, rather than by a chemical reaction. The pressures and energy densities that can be achieved, while insufficient for high-performance rocketry and firearms, are adequate for most applications, in which case compressed fluids offer a simpler, safer, and more practical source of propellant pressure. A compressed fluid propellant may simply be a pressurized gas, or a substance which is

1001-448: A double-column plant, the liquid oxygen produced will contain small quantities of krypton and xenon. By additional fractional distillation, the liquid oxygen may be enriched to contain 0.1–0.2% of a krypton/xenon mixture, which is extracted either by adsorption onto silica gel or by distillation. Finally, the krypton/xenon mixture may be separated into krypton and xenon by further distillation. Worldwide production of xenon in 1998

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1092-477: A few chemical reactions such as the formation of xenon hexafluoroplatinate , the first noble gas compound to be synthesized. Xenon is used in flash lamps and arc lamps , and as a general anesthetic . The first excimer laser design used a xenon dimer molecule (Xe 2 ) as the lasing medium , and the earliest laser designs used xenon flash lamps as pumps . Xenon is also used to search for hypothetical weakly interacting massive particles and as

1183-431: A gas at atmospheric pressure, but stored under pressure as a liquid. In applications in which a large quantity of propellant is used, such as pressure washing and airbrushing , air may be pressurized by a compressor and used immediately. Additionally, a hand pump to compress air can be used for its simplicity in low-tech applications such as atomizers , plant misters and water rockets . The simplest examples of such

1274-438: A large number of xenon compounds have been discovered and described. Almost all known xenon compounds contain the electronegative atoms fluorine or oxygen. The chemistry of xenon in each oxidation state is analogous to that of the neighboring element iodine in the immediately lower oxidation state. Three fluorides are known: XeF 2 , XeF 4 , and XeF 6 . XeF is theorized to be unstable. These are

1365-425: A less electronegative element include F–Xe–N(SO 2 F) 2 and F–Xe–BF 2 . The latter is synthesized from dioxygenyl tetrafluoroborate, O 2 BF 4 , at −100 °C. Propellant A propellant (or propellent ) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion , and "propel"

1456-474: A liquid, xenon has a density of up to 3.100 g/mL, with the density maximum occurring at the triple point. Liquid xenon has a high polarizability due to its large atomic volume, and thus is an excellent solvent. It can dissolve hydrocarbons, biological molecules, and even water. Under the same conditions, the density of solid xenon, 3.640 g/cm , is greater than the average density of granite , 2.75 g/cm . Under gigapascals of pressure , xenon forms

1547-407: A metallic phase. Solid xenon changes from Face-centered cubic (fcc) to hexagonal close packed (hcp) crystal phase under pressure and begins to turn metallic at about 140 GPa, with no noticeable volume change in the hcp phase. It is completely metallic at 155 GPa. When metallized, xenon appears sky blue because it absorbs red light and transmits other visible frequencies. Such behavior

1638-402: A modest pressure. This pressure is high enough to provide useful propulsion of the payload (e.g. aerosol paint, deodorant, lubricant), but is low enough to be stored in an inexpensive metal can, and to not pose a safety hazard in case the can is ruptured. The mixture of liquid and gaseous propellant inside the can maintains a constant pressure, called the liquid's vapor pressure . As the payload

1729-504: A pale-yellow solid. It explodes above −35.9 °C into xenon and oxygen gas, but is otherwise stable. A number of xenon oxyfluorides are known, including XeOF 2 , XeOF 4 , XeO 2 F 2 , and XeO 3 F 2 . XeOF 2 is formed by reacting OF 2 with xenon gas at low temperatures. It may also be obtained by partial hydrolysis of XeF 4 . It disproportionates at −20 °C into XeF 2 and XeO 2 F 2 . XeOF 4

1820-409: A propellant backwards which creates an opposite force that moves the vehicle forward. Projectiles can use propellants that are expanding gases which provide the motive force to set the projectile in motion. Aerosol cans use propellants which are fluids that are compressed so that when the propellant is allowed to escape by releasing a valve, the energy stored by the compression moves the propellant out of

1911-442: A propellant because they move at relativistic speed, i.e., the speed of light. In this case Newton's third Law of Motion is inadequate to model the physics involved and relativistic physics must be used. In chemical rockets, chemical reactions are used to produce energy which creates movement of a fluid which is used to expel the products of that chemical reaction (and sometimes other substances) as propellants. For example, in

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2002-588: A real compound. Theoretical calculations indicate that the linear molecule XeCl 2 is less stable than the van der Waals complex. Xenon tetrachloride and xenon dibromide are even more unstable and they cannot be synthesized by chemical reactions. They were created by radioactive decay of ICl 4 and IBr 2 , respectively. Three oxides of xenon are known: xenon trioxide ( XeO 3 ) and xenon tetroxide ( XeO 4 ), both of which are dangerously explosive and powerful oxidizing agents, and xenon dioxide (XeO 2 ), which

2093-488: A simple hydrogen/oxygen engine, hydrogen is burned (oxidized) to create H 2 O and the energy from the chemical reaction is used to expel the water (steam) to provide thrust. Often in chemical rocket engines, a higher molecular mass substance is included in the fuel to provide more reaction mass. Rocket propellant may be expelled through an expansion nozzle as a cold gas, that is, without energetic mixing and combustion, to provide small changes in velocity to spacecraft by

2184-478: A substrate of chilled crystal of nickel to spell out the three-letter company initialism. It was the first-time atoms had been precisely positioned on a flat surface. Xenon has atomic number 54; that is, its nucleus contains 54 protons . At standard temperature and pressure , pure xenon gas has a density of 5.894 kg/m , about 4.5 times the density of the Earth's atmosphere at sea level, 1.217 kg/m . As

2275-451: A system are squeeze bottles for such liquids as ketchup and shampoo. However, compressed gases are impractical as stored propellants if they do not liquify inside the storage container, because very high pressures are required in order to store any significant quantity of gas, and high-pressure gas cylinders and pressure regulators are expensive and heavy. Liquefied gas propellants are gases at atmospheric pressure, but become liquid at

2366-494: A total mass of the atmosphere of 5.15 × 10 kilograms (1.135 × 10  lb), the atmosphere contains on the order of 2.03 gigatonnes (2.00 × 10 long tons; 2.24 × 10 short tons) of xenon in total when taking the average molar mass of the atmosphere as 28.96 g/mol which is equivalent to some 394-mass ppb. Xenon is obtained commercially as a by-product of the separation of air into oxygen and nitrogen . After this separation, generally performed by fractional distillation in

2457-497: A variety of usually ionized propellants, including atomic ions, plasma, electrons, or small droplets or solid particles as propellant. If the acceleration is caused mainly by the Coulomb force (i.e. application of a static electric field in the direction of the acceleration) the device is considered electrostatic. The types of electrostatic drives and their propellants: These are engines that use electromagnetic fields to generate

2548-410: A vehicle, projectile , or fluid payload. In vehicles, the engine that expels the propellant is called a reaction engine . Although technically a propellant is the reaction mass used to create thrust, the term "propellant" is often used to describe a substance which contains both the reaction mass and the fuel that holds the energy used to accelerate the reaction mass. For example, the term "propellant"

2639-447: Is a member of the zero- valence elements that are called noble or inert gases . It is inert to most common chemical reactions (such as combustion, for example) because the outer valence shell contains eight electrons. This produces a stable, minimum energy configuration in which the outer electrons are tightly bound. In a gas-filled tube , xenon emits a blue or lavenderish glow when excited by electrical discharge . Xenon emits

2730-504: Is about 3% fission products) than it does in air. However, there is as of 2022 no commercial effort to extract xenon from spent fuel during nuclear reprocessing . Naturally occurring xenon is composed of seven stable isotopes : Xe, Xe, and Xe. The isotopes Xe and Xe are predicted by theory to undergo double beta decay , but this has never been observed so they are considered stable. In addition, more than 40 unstable isotopes have been studied. The longest-lived of these isotopes are

2821-523: Is called a reaction engine . Although the term "propellant" is often used in chemical rocket design to describe a combined fuel/propellant, propellants should not be confused with the fuel that is used by an engine to produce the energy that expels the propellant. Even though the byproducts of substances used as fuel are also often used as a reaction mass to create the thrust, such as with a chemical rocket engine, propellant and fuel are two distinct concepts. In electrically powered spacecraft , electricity

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2912-440: Is depleted, the propellant vaporizes to fill the internal volume of the can. Liquids are typically 500-1000x denser than their corresponding gases at atmospheric pressure; even at the higher pressure inside the can, only a small fraction of its volume needs to be propellant in order to eject the payload and replace it with vapor. Vaporizing the liquid propellant to gas requires some energy, the enthalpy of vaporization , which cools

3003-459: Is formed by the partial hydrolysis of XeF 6 ... ...or the reaction of XeF 6 with sodium perxenate, Na 4 XeO 6 . The latter reaction also produces a small amount of XeO 3 F 2 . XeO 2 F 2 is also formed by partial hydrolysis of XeF 6 . XeOF 4 reacts with CsF to form the XeOF 5 anion, while XeOF 3 reacts with

3094-436: Is generated by electricity: Nuclear reactions may be used to produce the energy for the expulsion of the propellants. Many types of nuclear reactors have been used/proposed to produce electricity for electrical propulsion as outlined above. Nuclear pulse propulsion uses a series of nuclear explosions to create large amounts of energy to expel the products of the nuclear reaction as the propellant. Nuclear thermal rockets use

3185-404: Is generated by passing brief electric current through a tube filled with xenon gas. In 1934, Edgerton was able to generate flashes as brief as one microsecond with this method. In 1939, American physician Albert R. Behnke Jr. began exploring the causes of "drunkenness" in deep-sea divers. He tested the effects of varying the breathing mixtures on his subjects, and discovered that this caused

3276-408: Is inadequate to model the physics involved and relativistic physics must be used. In chemical rockets, chemical reactions are used to produce energy which creates movement of a fluid which is used to expel the products of that chemical reaction (and sometimes other substances) as propellants. For example, in a simple hydrogen/oxygen engine, hydrogen is burned (oxidized) to create H 2 O and

3367-401: Is not produced directly but as a product of successive beta decays and thus it cannot absorb any neutrons in a nuclear explosion which occurs in fractions of a second. The stable isotope xenon-132 has a fission product yield of over 4% in the thermal neutron fission of U which means that stable or nearly stable xenon isotopes have a higher mass fraction in spent nuclear fuel (which

3458-473: Is often used in chemical rocket design to describe a combined fuel/propellant, although the propellants should not be confused with the fuel that is used by an engine to produce the energy that expels the propellant. Even though the byproducts of substances used as fuel are also often used as a reaction mass to create the thrust, such as with a chemical rocket engine, propellant and fuel are two distinct concepts. Vehicles can use propellants to move by ejecting

3549-417: Is simply heated using resistive heating as it is expelled to create more thrust. In chemical rockets and aircraft, fuels are used to produce an energetic gas that can be directed through a nozzle , thereby producing thrust. In rockets, the burning of rocket fuel produces an exhaust, and the exhausted material is usually expelled as a propellant under pressure through a nozzle . The exhaust material may be

3640-431: Is stored in the compressed fluid used to expel the fluid as the propellant. The energy stored in the fluid was added to the system when the fluid was compressed, such as compressed air . The energy applied to the pump or thermal system that is used to compress the air is stored until it is released by allowing the propellant to escape. Compressed fluid may also be used only as energy storage along with some other substance as

3731-532: Is the most significant (and unwanted) neutron absorber in nuclear reactors . Xenon was discovered in England by the Scottish chemist William Ramsay and English chemist Morris Travers on July 12, 1898, shortly after their discovery of the elements krypton and neon . They found xenon in the residue left over from evaporating components of liquid air . Ramsay suggested the name xenon for this gas from

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3822-417: Is unusual for a metal and is explained by the relatively small width of the electron bands in that state. Liquid or solid xenon nanoparticles can be formed at room temperature by implanting Xe ions into a solid matrix. Many solids have lattice constants smaller than solid Xe. This results in compression of the implanted Xe to pressures that may be sufficient for its liquefaction or solidification. Xenon

3913-409: Is used to accelerate the propellant. An electrostatic force may be used to expel positive ions, or the Lorentz force may be used to expel negative ions and electrons as the propellant. Electrothermal engines use the electromagnetic force to heat low molecular weight gases (e.g. hydrogen, helium, ammonia) into a plasma and expel the plasma as propellant. In the case of a resistojet rocket engine,

4004-400: Is used to compress the air is stored until it is released by allowing the propellant to escape. Compressed fluid may also be used only as energy storage along with some other substance as the propellant, such as with a water rocket , where the energy stored in the compressed air is the fuel and the water is the propellant. In electrically powered spacecraft , electricity is used to accelerate

4095-513: Is weakly acidic, dissolving in alkali to form unstable xenate salts containing the HXeO 4 anion. These unstable salts easily disproportionate into xenon gas and perxenate salts, containing the XeO 6 anion. Barium perxenate, when treated with concentrated sulfuric acid , yields gaseous xenon tetroxide: To prevent decomposition, the xenon tetroxide thus formed is quickly cooled into

4186-495: The Chernobyl nuclear accident . Stable or extremely long lived isotopes of xenon are also produced in appreciable quantities in nuclear fission. Xenon-136 is produced when xenon-135 undergoes neutron capture before it can decay. The ratio of xenon-136 to xenon-135 (or its decay products) can give hints as to the power history of a given reactor and the absence of xenon-136 is a "fingerprint" for nuclear explosions, as xenon-135

4277-478: The Greek word ξένον xénon , neuter singular form of ξένος xénos , meaning 'foreign(er)', 'strange(r)', or 'guest'. In 1902, Ramsay estimated the proportion of xenon in the Earth's atmosphere to be one part in 20 million. During the 1930s, American engineer Harold Edgerton began exploring strobe light technology for high speed photography . This led him to the invention of the xenon flash lamp in which light

4368-432: The gas phase and several days in deeply frozen solid xenon. In contrast, Xe has a nuclear spin value of 3 ⁄ 2 and a nonzero quadrupole moment , and has t 1 relaxation times in the millisecond and second ranges. Some radioactive isotopes of xenon (for example, Xe and Xe) are produced by neutron irradiation of fissionable material within nuclear reactors . Xe is of considerable significance in

4459-399: The outgassing of xenon into the atmosphere. Unlike the lower-mass noble gases, the normal stellar nucleosynthesis process inside a star does not form xenon. Nucleosynthesis consumes energy to produce nuclides more massive than iron-56 , and thus the synthesis of xenon represents no energy gain for a star. Instead, xenon is formed during supernova explosions during the r-process , by

4550-429: The primordial Xe, which undergoes double electron capture with a half-life of 1.8 × 10  yr , and Xe, which undergoes double beta decay with a half-life of 2.11 × 10 yr . Xe is produced by beta decay of I , which has a half-life of 16 million years. Xe, Xe, Xe, and Xe are some of the fission products of U and Pu , and are used to detect and monitor nuclear explosions. Nuclei of two of

4641-420: The alkali metal fluorides KF , RbF and CsF to form the XeOF 4 anion. Xenon can be directly bonded to a less electronegative element than fluorine or oxygen, particularly carbon . Electron-withdrawing groups, such as groups with fluorine substitution, are necessary to stabilize these compounds. Numerous such compounds have been characterized, including: Other compounds containing xenon bonded to

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4732-517: The atmosphere of planet Jupiter is unusually high, about 2.6 times that of the Sun. This abundance remains unexplained, but may have been caused by an early and rapid buildup of planetesimals —small, sub-planetary bodies—before the heating of the presolar disk ; otherwise, xenon would not have been trapped in the planetesimal ices. The problem of the low terrestrial xenon may be explained by covalent bonding of xenon to oxygen within quartz , reducing

4823-564: The burning of the fuel and, as a consequence, thrust vs time profile. There are three types of burns that can be achieved with different grains. There are four different types of solid fuel/propellant compositions: In rockets, three main liquid bipropellant combinations are used: cryogenic oxygen and hydrogen, cryogenic oxygen and a hydrocarbon, and storable propellants. Propellant combinations used for liquid propellant rockets include: Common monopropellant used for liquid rocket engines include: Electrically powered reactive engines use

4914-425: The can and that propellant forces the aerosol payload out along with the propellant. Compressed fluid may also be used as a simple vehicle propellant, with the potential energy that is stored in the compressed fluid used to expel the fluid as the propellant. The energy stored in the fluid was added to the system when the fluid was compressed, such as compressed air . The energy applied to the pump or thermal system that

5005-403: The compressed propellant is simply heated using resistive heating as it is expelled to create more thrust. In chemical rockets and aircraft, fuels are used to produce an energetic gas that can be directed through a nozzle , thereby producing thrust. In rockets, the burning of rocket fuel produces an exhaust, and the exhausted material is usually expelled as a propellant under pressure through

5096-495: The course of the mission. It used 2.3 kW of electrical power and was the primary propulsion for the probe. The second interplanetary mission using NSTAR engine was the Dawn spacecraft , launched in 2007 with three redundant units with a 30 cm diameter each. Dawn is the first NASA exploratory mission to use ion propulsion to enter and leave more than one orbit. Dawn carried 425 kg (937 lb) of on-board xenon propellant, and

5187-682: The design to increase the reactor's reactivity (the number of neutrons per fission that go on to fission other atoms of nuclear fuel ). Xe reactor poisoning was a major factor in the Chernobyl disaster . A shutdown or decrease of power of a reactor can result in buildup of Xe, with reactor operation going into a condition known as the iodine pit . Under adverse conditions, relatively high concentrations of radioactive xenon isotopes may emanate from cracked fuel rods , or fissioning of uranium in cooling water . Isotope ratios of xenon produced in natural nuclear fission reactors at Oklo in Gabon reveal

5278-652: The disadvantage of being flammable . Nitrous oxide and carbon dioxide are also used as propellants to deliver foodstuffs (for example, whipped cream and cooking spray ). Medicinal aerosols such as asthma inhalers use hydrofluoroalkanes (HFA): either HFA 134a (1,1,1,2,-tetrafluoroethane) or HFA 227 (1,1,1,2,3,3,3-heptafluoropropane) or combinations of the two. More recently, liquid hydrofluoroolefin (HFO) propellants have become more widely adopted in aerosol systems due to their relatively low vapor pressure, low global warming potential (GWP), and nonflammability. The practicality of liquified gas propellants allows for

5369-513: The divers to perceive a change in depth. From his results, he deduced that xenon gas could serve as an anesthetic . Although Russian toxicologist Nikolay V. Lazarev apparently studied xenon anesthesia in 1941, the first published report confirming xenon anesthesia was in 1946 by American medical researcher John H. Lawrence, who experimented on mice. Xenon was first used as a surgical anesthetic in 1951 by American anesthesiologist Stuart C. Cullen, who successfully used it with two patients. Xenon and

5460-399: The energy from the chemical reaction is used to expel the water (steam) to provide thrust. Often in chemical rocket engines, a higher molecular mass substance is included in the fuel to provide more reaction mass. Rocket propellant may be expelled through an expansion nozzle as a cold gas, that is, without energetic mixing and combustion, to provide small changes in velocity to spacecraft by

5551-421: The engine produces just 92 millinewtons (0.331 ounce-force ) thrust at maximum power (2,100W on DS1 mission), the craft achieved high speed because ion engines thrust continuously for long periods of time. "The 30-cm ion thruster operates over a 0.5 kW to 2.3 kW input power range providing thrust from 19 mN to 92 mN. The specific impulse ranges from 1900 s at 0.5 kW to 3100 s at 2.3 kW." The NSTAR ion thruster

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5642-419: The form of an overabundance of xenon-129. He inferred that this was a decay product of radioactive iodine-129 . This isotope is produced slowly by cosmic ray spallation and nuclear fission , but is produced in quantity only in supernova explosions. Because the half-life of I is comparatively short on a cosmological time scale (16 million years), this demonstrated that only a short time had passed between

5733-461: The heat of a nuclear reaction to heat a propellant. Usually the propellant is hydrogen because the force is a function of the energy irrespective of the mass of the propellant, so the lightest propellant (hydrogen) produces the greatest specific impulse . A photonic reactive engine uses photons as the propellant and their discrete relativistic energy to produce thrust. Compressed fluid or compressed gas propellants are pressurized physically, by

5824-514: The much more plentiful argon, which makes up over 1% by volume of earth's atmosphere, costs less than a cent per liter. Within the Solar System, the nucleon fraction of xenon is 1.56 × 10 , for an abundance of approximately one part in 630 thousand of the total mass. Xenon is relatively rare in the Sun 's atmosphere, on Earth , and in asteroids and comets . The abundance of xenon in

5915-402: The newly synthesized bishomocubane based compounds are under consideration in the research stage as both solid and liquid propellants of the future. Solid fuel/propellants are used in forms called grains . A grain is any individual particle of fuel/propellant regardless of the size or shape. The shape and size of a grain determines the burn time, amount of gas, and rate of produced energy from

6006-421: The noble gases argon , krypton , and radon , including argon fluorohydride (HArF), krypton difluoride (KrF 2 ), and radon fluoride . By 1971, more than 80 xenon compounds were known. In November 1989, IBM scientists demonstrated a technology capable of manipulating individual atoms . The program, called IBM in atoms , used a scanning tunneling microscope to arrange 35 individual xenon atoms on

6097-492: The operation of nuclear fission reactors . Xe has a huge cross section for thermal neutrons , 2.6×10   barns , and operates as a neutron absorber or " poison " that can slow or stop the chain reaction after a period of operation. This was discovered in the earliest nuclear reactors built by the American Manhattan Project for plutonium production. However, the designers had made provisions in

6188-539: The other noble gases were for a long time considered to be completely chemically inert and not able to form compounds . However, while teaching at the University of British Columbia , Neil Bartlett discovered that the gas platinum hexafluoride (PtF 6 ) was a powerful oxidizing agent that could oxidize oxygen gas (O 2 ) to form dioxygenyl hexafluoroplatinate ( O 2 [PtF 6 ] ). Since O 2 (1165 kJ/mol) and xenon (1170 kJ/mol) have almost

6279-553: The presence of NaF yields high-purity XeF 4 . The xenon fluorides behave as both fluoride acceptors and fluoride donors, forming salts that contain such cations as XeF and Xe 2 F 3 , and anions such as XeF 5 , XeF 7 , and XeF 8 . The green, paramagnetic Xe 2 is formed by the reduction of XeF 2 by xenon gas. XeF 2 also forms coordination complexes with transition metal ions. More than 30 such complexes have been synthesized and characterized. Whereas

6370-530: The propellant). Chlorofluorocarbons (CFCs) were once often used as propellants, but since the Montreal Protocol came into force in 1989, they have been replaced in nearly every country due to the negative effects CFCs have on Earth's ozone layer . The most common replacements of CFCs are mixtures of volatile hydrocarbons , typically propane , n- butane and isobutane . Dimethyl ether (DME) and methyl ethyl ether are also used. All these have

6461-414: The propellant, such as with a water rocket , where the energy stored in the compressed air is the fuel and the water is the propellant. Proposed photon rockets would use the relativistic momentum of photons to create thrust. Even though photons do not have mass, they can still act as a propellant because they move at relativistic speed, i.e., the speed of light. In this case Newton's third Law of Motion

6552-413: The propellant. An electrostatic force may be used to expel positive ions, or the Lorentz force may be used to expel negative ions and electrons as the propellant. Electrothermal engines use the electromagnetic force to heat low molecular weight gases (e.g. hydrogen, helium, ammonia) into a plasma and expel the plasma as propellant. In the case of a resistojet rocket engine, the compressed propellant

6643-507: The reactor properties during chain reaction that took place about 2 billion years ago. Because xenon is a tracer for two parent isotopes, xenon isotope ratios in meteorites are a powerful tool for studying the formation of the Solar System . The iodine–xenon method of dating gives the time elapsed between nucleosynthesis and the condensation of a solid object from the solar nebula . In 1960, physicist John H. Reynolds discovered that certain meteorites contained an isotopic anomaly in

6734-412: The result may indicate that Mars lost most of its primordial atmosphere, possibly within the first 100 million years after the planet was formed. In another example, excess Xe found in carbon dioxide well gases from New Mexico is believed to be from the decay of mantle -derived gases from soon after Earth's formation. After Neil Bartlett's discovery in 1962 that xenon can form chemical compounds,

6825-492: The same first ionization potential , Bartlett realized that platinum hexafluoride might also be able to oxidize xenon. On March 23, 1962, he mixed the two gases and produced the first known compound of a noble gas, xenon hexafluoroplatinate . Bartlett thought its composition to be Xe [PtF 6 ] , but later work revealed that it was probably a mixture of various xenon-containing salts. Since then, many other xenon compounds have been discovered, in addition to some compounds of

6916-428: The same rate it is produced during steady operation of a nuclear reactor. However, if power is reduced or the reactor is scrammed , less xenon is destroyed than is produced from the beta decay of its parent nuclides . This phenomenon called xenon poisoning can cause significant problems in restarting a reactor after a scram or increasing power after it had been reduced and it was one of several contributing factors in

7007-429: The slow neutron-capture process ( s-process ) in red giant stars that have exhausted their core hydrogen and entered the asymptotic giant branch , and from radioactive decay, for example by beta decay of extinct iodine-129 and spontaneous fission of thorium , uranium , and plutonium . Xenon-135 is a notable neutron poison with a high fission product yield . As it is relatively short lived, it decays at

7098-420: The solar gas cloud. In a similar way, xenon isotopic ratios such as Xe/ Xe and Xe/ Xe are a powerful tool for understanding planetary differentiation and early outgassing. For example, the atmosphere of Mars shows a xenon abundance similar to that of Earth (0.08 parts per million ) but Mars shows a greater abundance of Xe than the Earth or the Sun. Since this isotope is generated by radioactive decay,

7189-441: The stable isotopes of xenon , Xe and Xe (both stable isotopes with odd mass numbers), have non-zero intrinsic angular momenta ( nuclear spins , suitable for nuclear magnetic resonance ). The nuclear spins can be aligned beyond ordinary polarization levels by means of circularly polarized light and rubidium vapor. The resulting spin polarization of xenon nuclei can surpass 50% of its maximum possible value, greatly exceeding

7280-416: The starting points for the synthesis of almost all xenon compounds. The solid, crystalline difluoride XeF 2 is formed when a mixture of fluorine and xenon gases is exposed to ultraviolet light. The ultraviolet component of ordinary daylight is sufficient. Long-term heating of XeF 2 at high temperatures under an NiF 2 catalyst yields XeF 6 . Pyrolysis of XeF 6 in

7371-423: The supernova and the time the meteorites had solidified and trapped the I. These two events (supernova and solidification of gas cloud) were inferred to have happened during the early history of the Solar System , because the I isotope was likely generated shortly before the Solar System was formed, seeding the solar gas cloud with isotopes from a second source. This supernova source may also have caused collapse of

7462-413: The system. This is usually insignificant, although it can sometimes be an unwanted effect of heavy usage (as the system cools, the vapor pressure of the propellant drops). However, in the case of a freeze spray , this cooling contributes to the desired effect (although freeze sprays may also contain other components, such as chloroethane , with a lower vapor pressure but higher enthalpy of vaporization than

7553-406: The thermal equilibrium value dictated by paramagnetic statistics (typically 0.001% of the maximum value at room temperature , even in the strongest magnets ). Such non-equilibrium alignment of spins is a temporary condition, and is called hyperpolarization . The process of hyperpolarizing the xenon is called optical pumping (although the process is different from pumping a laser ). Because

7644-413: The use of cold gas thrusters , usually as maneuvering thrusters. To attain a useful density for storage, most propellants are stored as either a solid or a liquid. A rocket propellant is a mass that is expelled from a vehicle, such as a rocket, in such a way as to create a thrust in accordance with Newton's third law of motion , and "propel" the vehicle forward. The engine that expels the propellant

7735-551: The use of cold gas thrusters , usually as maneuvering thrusters. To attain a useful density for storage, most propellants are stored as either a solid or a liquid. Propellants may be energized by chemical reactions to expel solid, liquid or gas. Electrical energy may be used to expel gases, plasmas, ions, solids or liquids. Photons may be used to provide thrust via relativistic momentum. Propellants that explode in operation are of little practical use currently, although there have been experiments with Pulse Detonation Engines . Also

7826-449: The xenon fluorides are well characterized, the other halides are not. Xenon dichloride , formed by the high-frequency irradiation of a mixture of xenon, fluorine, and silicon or carbon tetrachloride , is reported to be an endothermic, colorless, crystalline compound that decomposes into the elements at 80 °C. However, XeCl 2 may be merely a van der Waals molecule of weakly bound Xe atoms and Cl 2 molecules and not

7917-530: Was able to perform a velocity change of 25,700 mph (11.49 km/s) over the mission. As of 2009 NASA engineers state that NSTAR engines, in the 5-kilowatt and 0.04 pound-thrust range, are candidates for propelling spacecraft to Europa , Pluto , and other small bodies in deep space. Xenon Xenon is a chemical element ; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo

8008-419: Was built for Deep Space 1 probe. One of the challenges was developing a compact and light weight power processing unit that converts power from the solar arrays into the voltages needed by the engine. The engine achieves a specific impulse of up to three thousand seconds. This is an order of magnitude higher than traditional space propulsion methods, resulting in a mass savings of approximately half. Although

8099-569: Was estimated at 5,000–7,000 cubic metres (180,000–250,000 cu ft). At a density of 5.894 grams per litre (0.0002129 lb/cu in) this is equivalent to roughly 30 to 40 tonnes (30 to 39 long tons; 33 to 44 short tons). Because of its scarcity, xenon is much more expensive than the lighter noble gases—approximate prices for the purchase of small quantities in Europe in 1999 were 10  € /L (=~€1.7/g) for xenon, 1 €/L (=~€0.27/g) for krypton, and 0.20 €/L (=~€0.22/g) for neon, while

8190-462: Was first used on the Deep Space 1 (DS1) spacecraft, launched on 24 October 1998. The Deep Space mission carried out a flyby of asteroid 9969 Braille and Comet Borrelly . Deep Space 1 had 178 pounds (81 kilograms) of xenon propellant, with a total impulse capability of 2.65 x10 Ns and was capable of increasing the speed of DS1 by 7900 miles per hour (12,700 kilometers per hour, 3.58 km/s) over

8281-398: Was reported in 2011 with a coordination number of four. XeO 2 forms when xenon tetrafluoride is poured over ice. Its crystal structure may allow it to replace silicon in silicate minerals. The XeOO cation has been identified by infrared spectroscopy in solid argon . Xenon does not react with oxygen directly; the trioxide is formed by the hydrolysis of XeF 6 : XeO 3

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