Thermobaric weapon

A thermobaric weapon is a specialized type of explosive munition. These weapons are often called aerosol bombs or vacuum bombs. The name "thermobaric" comes from two Greek words. "Thermos" means hot, and "baros" means weight or pressure. Unlike conventional explosives, which use a pre-mixed fuel and oxidizer, thermobaric weapons use only fuel. They rely on the oxygen found in the surrounding atmosphere to complete the chemical combustion. Because they do not carry their own oxidizer, they can be significantly more energetic than standard explosives of the same weight.

The mechanism of a thermobaric weapon involves a two-step process. First, an initial explosive charge, known as a scatter charge, detonates upon impact. This charge breaks open the munition's container and disperses the fuel as a large aerosol cloud. This cloud can consist of gas, liquid, or even powdered materials. The fuel might be organic materials or powdered metals like magnesium or aluminum. This cloud is capable of flowing around obstacles and into enclosed structures.

Once the fuel is dispersed, a second charge ignites the cloud. This creates a massive, sustained blast wave. In a conventional explosion, the blast comes from a single point. In a thermobaric explosion, the flame front accelerates to a massive volume. This creates pressure fronts within both the fuel mixture and the surrounding air. The blast wave often lasts much longer than a typical explosion. In some confined settings, reflective shock waves can extend the fireball's duration to between 10 and 50 milliseconds. As the gases cool, the pressure drops sharply. This creates a partial vacuum, which is the reason for the name "vacuum bomb."

Thermobaric weapons are most effective in enclosed or semi-enclosed spaces. This includes tunnels, buildings, bunkers, caves, and foxholes. The fuel cloud can seep into these areas before the ignition occurs. Because of this, traditional countermeasures like sandbags or personal armor are often ineffective. A study by the US Central Intelligence Agency suggested a unique danger to people in these areas. The shock and pressure waves might cause minimal damage to brain tissue. This could mean victims are not knocked unconscious but instead suffer from suffocation for several minutes.

The history of these weapons began with early German attempts. During World War I, incendiary shells used tar-impregnated tissue and gunpowder dust. These shells could burn for about two minutes. In World War II, the physicist Mario Zippermayr directed research into these weapons for the German Wehrmacht. Later, the United States developed fuel-air explosives (FAE) for use during the Vietnam War. The US Naval Weapons Center at China Lake was involved in developing the CBU-55 cluster bomb. Following these developments, Soviet scientists also created their own versions of FAE technology.

Modern technology has produced many different types of these munitions. The United States uses various models, including the BLU-73 and the BLU-95. They also use the XM1060 40-mm grenade, which was used in Afghanistan to target caves. The US Marine Corps uses the SMAW-NE, a "Novel Explosive" round for the Mk 153 SMAW launcher. Russia has also developed a wide array of third-generation warheads. For example, the RPO-A is an infantry-portable rocket. The GM-94 is a pump-action grenade launcher that fires a 1.5-kilogram grenade. This grenade has a lethality radius of 15 meters.

Advanced systems provide even greater scale and range. The Russian TOS-1 is a dedicated vehicle with 24 launch tubes. A single full salvo from this system can cover a large rectangular area. Other sophisticated tools include the RShG-1, which is a powerful variant of the RPG-27. The RMG uses a tandem-charge system. This features a high-explosive anti-tank warhead that blasts an opening for the thermobaric charge to enter. Some anti-tank missiles, like the Kornet, also feature thermobaric variants. The Kornet-EM can reach a maximum range of 5.5 kilometers.