Editing Thermobaric weapon (section)

==Mechanism==
<gallery mode="packed" caption="Demonstration of an open-air dust explosion">
File:Dust explosion 00.jpg|Experimental setup
File:Dust explosion 01.jpg|Finely-ground [[flour]] is dispersed
File:Dust explosion 02.jpg|Cloud of flour is ignited
File:Dust explosion 03.jpg|Fireball spreads rapidly
File:Dust explosion 04.jpg|Intense [[radiant heat]] has nothing to ignite here
File:Dust explosion 05.jpg|Fireball and superheated gases rise
File:Dust explosion 06.jpg|Aftermath of explosion, with unburned flour on the ground
</gallery>

Most [[explosive|conventional explosives]] consist of a [[fuel]]–[[oxidiser]] premix, but thermobaric weapons consist only of fuel and as a result are significantly more energetic than conventional explosives of equal weight.<ref name="Parsons02032022">{{Cite web |last=Parsons |first=Jeff |url=https://metro.co.uk/2022/03/01/what-is-a-thermobaric-weapon-putin-accused-of-using-vacuum-bomb-16194023/ |title=What is a thermobaric weapon? Putin accused of using devastating 'vacuum bomb' in Ukraine |work=Metro |date=2 March 2022}}</ref> Their reliance on atmospheric oxygen makes them unsuitable for use under water, at high altitude, and in adverse weather. They are, however, considerably more effective when used in enclosed spaces such as tunnels, buildings, and non-hermetically sealed [[fortification|field fortifications]] ([[Defensive fighting position#Terminology|foxholes]], [[bunker]]s).<ref>{{Cite journal |last=Türker |first=Lemi |date=2016-12-01 |title=Thermobaric and enhanced blast explosives (TBX and EBX) |journal=Defence Technology |language=en |volume=12 |issue=6 |pages=423–445 |doi=10.1016/j.dt.2016.09.002 |s2cid=138647940 |issn=2214-9147|doi-access=free }}</ref><ref>Lester W. Grau and Timothy Smith, [https://community.apan.org/cfs-file/__key/docpreview-s/00-00-08-52-45/2000_2D00_08_2D00_01-A-Crushing-Victory_2D00_Fuel_2D00_Air-Explosives-and-Grozny-2000-_2800_Grau-and-Smith_2900_.pdf A 'Crushing' Victory: Fuel-Air Explosives and Grozny 2000], August 2000</ref>

The initial explosive charge detonates as it hits its target, opening the container and dispersing the fuel mixture as a cloud.<ref>{{Cite news |date=2 March 2022 |title=Ukraine conflict: What is a vacuum or thermobaric bomb? |publisher=BBC News |url=https://www.bbc.com/news/business-60571395 |access-date=2 March 2022 |archive-date=1 March 2022 |archive-url=https://web.archive.org/web/20220301215057/https://www.bbc.com/news/business-60571395}}</ref> The typical [[blast wave]] of a thermobaric weapon lasts significantly longer than that of a conventional explosive.

In contrast to an explosive that uses [[oxidation]] in a confined region to produce a [[blast front]] emanating from a single source, a thermobaric flame front accelerates to a large volume, which produces pressure fronts within the mixture of fuel and oxidant and then also in the surrounding air.<ref>Nettleton, ''J. Occ. Accidents'', 1, 149 (1976).</ref>

Thermobaric explosives apply the principles underlying accidental unconfined vapor cloud explosions, which include those from dispersions of flammable dusts and droplets.<ref>Strehlow, 14th. Symp. (Int.) Comb. 1189, Comb. Inst. (1973).</ref> Such [[dust explosion]]s happened most often in [[flour mill]]s and their storage containers, grain bins (corn silos etc.), and earlier in coal mines, prior to the 20th century. Accidental unconfined vapor cloud explosions now happen most often in partially or completely empty oil tankers, refinery tanks, and vessels, such as the [[Buncefield fire]] in the United Kingdom in 2005, where the blast wave woke people {{convert|150|km}} from its centre.<ref>Health and Safety Environmental Agency, 5th and final report, 2008.</ref>

A typical weapon consists of a container packed with a fuel substance, the centre of which has a small conventional-explosive "scatter charge". Fuels are chosen on the basis of the exothermicity of their oxidation, ranging from powdered metals, such as aluminium or magnesium, to organic materials, possibly with a self-contained partial oxidant.<ref name="brousseau02">{{cite journal |doi=10.1002/1521-4087(200211)27:5<300::AID-PREP300>3.0.CO;2-#|title=Nanometric Aluminum in Explosives |year=2002 |last1=Brousseau |first1=Patrick |last2=Anderson |first2=C. John |journal=Propellants, Explosives, Pyrotechnics |volume=27 |issue=5 |pages=300–306 }}</ref> The most recent development involves the use of [[Nano-thermite|nanofuels]].<ref>See Nanofuel/Oxidizers For Energetic Compositions – John D. Sullivan and Charles N. Kingery (1994) [http://www.google.com/patents/download/High_explosive_disseminator_for_a_high_e.pdf?id=aQcfAAAAEBAJ&output=pdf&sig=ACfU3U0D25d59F-VCDTZzGw3OgjvjmgYKA High explosive disseminator for a high explosive air bomb]{{dead link|date=June 2024|bot=medic}}{{cbignore|bot=medic}}</ref><ref>Slavica Terzić, Mirjana Dakić Kolundžija, Milovan Azdejković and Gorgi Minov (2004) [http://www.vti.mod.gov.rs/ntp/rad2004/34-04/terz/terz.pdf Compatibility Of Thermobaric Mixtures Based On Isopropyl Nitrate And Metal Powders] {{Webarchive|url=https://web.archive.org/web/20120302235504/http://www.vti.mod.gov.rs/ntp/rad2004/34-04/terz/terz.pdf |date=2012-03-02}}.</ref>

A thermobaric bomb's effective yield depends on a combination of a number of factors such as how well the fuel is dispersed, how rapidly it mixes with the surrounding atmosphere and the initiation of the igniter and its position relative to the container of fuel. In some designs, strong munitions cases allow the blast pressure to be contained long enough for the fuel to be heated well above its autoignition temperature so that once the container bursts, the superheated fuel autoignites progressively as it comes into contact with atmospheric oxygen.<ref>{{cite book |first=Rudolf |last=Meyer |author2=Josef Köhler |author3=Axel Homburg |title=Explosives |publisher=Wiley-VCH |location=Weinheim |year=2007 |pages=[https://books.google.com/books?id=ATiYCfo1VcEC&dq=thermobaric+heat+of+combustion&pg=PA312 312] |isbn=978-3-527-31656-4 |oclc=165404124}}</ref>
Conventional upper and lower [[flammability limit|limits of flammability]] apply to such weapons. Close in, blast from the dispersal charge, compressing and heating the surrounding atmosphere, has some influence on the lower limit. The upper limit has been demonstrated to influence the ignition of fogs above pools of oil strongly.<ref>Nettleton, arch. combust. 1,131, (1981).</ref> That weakness may be eliminated by designs in which the fuel is preheated well above its ignition temperature so that its cooling during its dispersion still results in a minimal ignition delay on mixing. The continual combustion of the outer layer of fuel molecules, as they come into contact with the air, generates added heat which maintains the temperature of the interior of the fireball, and thus sustains the detonation.<ref>Stephen B. Murray [http://www.galcit.caltech.edu/~jeshep/icders/cd-rom/EXTABS/259_20TH.PDF Fundamental and Applied Studies of Fuel-Air Detonation] {{Webarchive|url=https://web.archive.org/web/20100119085407/http://www.galcit.caltech.edu/~jeshep/icders/cd-rom/EXTABS/259_20TH.PDF |date=2010-01-19}}.</ref>

In confinement, a series of reflective shock waves is generated,<ref>Nettleton, Comb. and Flame, 24,65 (1975).</ref><ref>Fire Prev. Sci. and Tech. No. 19,4 (1976)</ref> which maintain the fireball and can extend its duration to between 10&nbsp;and&nbsp;50&nbsp;ms as exothermic recombination reactions occur.<ref>May L.Chan (2001) [http://www.google.com/patents/pdf/Advanced_thermobaric_explosive_compositi.pdf?id=JXoUAAAAEBAJ&output=pdf&sig=ACfU3U16E20UIEsFi1huKx0obKjXhYCs3w Advanced Thermobaric Explosive Compositions]{{dead link|date=June 2024|bot=medic}}{{cbignore|bot=medic}}.</ref> Further damage can result as the gases cool and pressure drops sharply, leading to a partial vacuum. This [[rarefaction]] effect has given rise to the misnomer "vacuum bomb". Piston-type afterburning{{clarify|date=March 2022}} is also believed to occur in such structures, as flame-fronts accelerate through it.<ref>{{cite web|url=http://www.sbir.gov/sbirsearch/detail/173278|title=New Thermobaric Materials and Weapon Concepts|author=Rozanski, Anthony J. |archiveurl=https://web.archive.org/web/20140518032215/http://www.sbir.gov/sbirsearch/detail/173278|archive-date=2014-05-18|url-status=dead}}.</ref>

===Fuel–air explosive===
A fuel–air explosive (FAE) device consists of a container of fuel and two separate explosive charges. After the munition is dropped or fired, the first explosive charge bursts open the container at a predetermined height and disperses the fuel in a cloud that mixes with [[atmospheric oxygen]] (the size of the cloud varies with the size of the munition). The cloud of fuel flows around objects and into structures. The second charge then detonates the cloud and creates a massive blast wave. The blast wave can destroy reinforced buildings, equipment, and kill or injure people. The blast wave's [[antipersonnel]] effect is magnified in confined spaces, such as [[Defensive fighting position#Terminology|foxhole]]s, tunnels, [[bunker]]s and caves.

====Effects====
Conventional countermeasures such as barriers (sandbags) and personnel armour are not effective against thermobaric weapons.<ref name="aewg03">{{cite journal |author=Anna E. Wildegger-Gaissmaier|title=Aspects of thermobaric weaponry |url=https://armscontrol.eu/wp-content/uploads/2012/06/thermobaric-weapons.pdf|journal=ADF Health|volume=4|date=April 2003|pages=3–6|s2cid=189802993}}</ref> A [[Human Rights Watch]] report of 1 February 2000<ref name=HRW1>{{cite web |url=https://www.hrw.org/en/reports/2000/02/01/backgrounder-russian-fuel-air-explosives-vacuum-bombs |title=Backgrounder on Russian Fuel Air Explosives ("Vacuum Bombs") &#124; Human Rights Watch |publisher=Hrw.org |date=1 February 2000 |access-date=23 April 2013 |archive-date=10 February 2013 |archive-url=https://web.archive.org/web/20130210004254/http://www.hrw.org/en/reports/2000/02/01/backgrounder-russian-fuel-air-explosives-vacuum-bombs |url-status=dead}}</ref> quotes a study made by the US [[Defense Intelligence Agency]]:

{{Blockquote|The [blast] kill mechanism against living targets is unique—and unpleasant.{{spaces}}... What kills is the [[longitudinal wave|pressure wave]], and more importantly, the subsequent [[rarefaction]] [vacuum], which [[Pneumothorax|ruptures the lungs]].{{spaces}}... If the fuel [[Deflagration|deflagrates]] but does not detonate, victims will be severely burned and will probably also inhale the burning fuel. Since the most common FAE fuels, [[ethylene oxide]] and [[propylene oxide]], are highly toxic, undetonated FAE should prove as lethal to personnel caught within the cloud as with most [[chemical agent]]s.}}

According to a US [[Central Intelligence Agency]] study,<ref name=HRW1/> 
{{blockquote|the effect of an FAE explosion within confined spaces is immense. Those near the ignition point are obliterated. Those at the fringe are likely to suffer many [[Internal injuries|internal]], invisible injuries, including [[Perforated eardrum|burst eardrums]] and crushed [[inner ear]] organs, severe [[concussions]], [[Barotrauma|ruptured lungs and internal organs]], and possibly [[blindness]].}}

Another Defense Intelligence Agency document speculates that, because the "shock and pressure waves cause minimal damage to [[brain tissue]]{{spaces}}... it is possible that victims of FAEs are not rendered unconscious by the blast, but instead suffer for several seconds or minutes while they suffocate".<ref name=HRW2>Defense Intelligence Agency, "Future Threat to the Soldier System, Volume I; Dismounted Soldier – Middle East Threat", September 1993, p. 73.</ref>