Electrothermal - chemical technology Electrothermal - chemical ( ETC ) technology is an attempt to increase accuracy and muzzle energy of future tank , artillery , and close - in weapon system guns by improving the predictability and rate of expansion of propellant s inside the barrel . An electrothermal - chemical gun uses a plasma cartridge to ignite and control the ammunition ' s propellant , using electrical energy to trigger the process . ETC increases the performance of conventional solid propellants , reduces the effect of temperature on propellant expansion and allows for more advanced , higher density propellants to be used . The technology has been under development since the mid - 1980s and at present is actively being researched in the United States by the Army Research Laboratory and private organizations . It is possible that electrothermal - chemical gun propulsion will be an integral part of US Army ' s future combat system and those of other countries such as Germany and the United Kingdom . Electrothermal - chemical technology is part of a broad research and development program that encompasses all electric gun technology , such as railgun s and coil gun s . Background . The constant battle between armour and armor - piercing round has caused a near constant development of the main battle tank design . The evolution of American anti - tank weapons can be traced back to requirements to combat Soviet tanks . In the late eighties , it was thought that the protection level of the Future Soviet Tank ( FST ) could exceed 700 mm of rolled homogeneous armour equivalence at its maximum thickness , which was effectively immune against the contemporary M - 829 armour piercing fin stabilized discarding sabot . Today it is estimated that a tank gun will have to achieve muzzle energies on the level of 18 MJ — which is double the muzzle energy of current tank gun systems — to be able to successfully penetrate such armour plating . In the eighties the most immediate method available to NATO to counter Soviet advances in armour technology was the adoption of a 140 mm main gun . This , however , required a redesigned turret that could incorporate the inherently larger breech and ammunition , and it also required some sort of automatic loader . Although the 140 mm gun was considered a real interim solution it was decided after the fall of the Soviet Union that the increase in muzzle energy it provided was not worth the increase in weight . Resources were therefore spent on research into other programs that could provide the needed muzzle energy . One of the most successful alternative technologies remains electrothermal - chemical ignition . Most proposed advances in gun technology are based on the assumption that the solid propellant as a stand alone propulsion system is no longer capable of delivering the required muzzle energy . This requirement has been underscored by the appearance of the Russia n T - 90 main battle tank . Even the elongation of current gun tubes , such as the new German 120 mm L / 55 , which was introduced by Rheinmetall is considered only an interim solution as it doesn ' t offer the required increase in muzzle velocity . Even advanced kinetic energy ammunition such as the United States ' M - 829A3 is considered only an interim solution against future threats . To that extent the solid propellant is considered to have reached the end of its usefulness , although it will remain the principal propulsion method for at least the next decade until newer technologies mature . To improve on the capabilities of a solid propellant weapon the electrothermal - chemical gun may see production as early as 2016 . ETC technology offers a medium - risk upgrade and is developed to the point that further improvements are so minor that it can be considered mature . The lightweight American 120 mm XM - 291 came close to achieving 17 MJ of muzzle energy , which is the lower - end muzzle energy spectrum for a 140 mm gun . However , the success of the XM - 291 doesn ' t imply the success of ETC technology as there are key parts of the propulsion system that are not yet understood or fully developed , such as the plasma ignition process . Nevertheless , there is substantial existing evidence that ETC technology is viable and something worth the money to continue development . Furthermore , it can be integrated into current gun systems . How it works . An electrothermal - chemical gun uses a plasma cartridge to ignite and control the ammunition ' s propellant , using electrical energy as a catalyst to begin the process . Originally researched by Dr . Jon Parmentola for the U . S . Army , it has grown into a very plausible successor to a standard solid propellant tank gun . Since the beginning of research the United States has funded the XM - 291 gun project with USD 4 , 000 , 000 , basic research with USD 300 , 000 , and applied research with USD 600 , 000 . Since then it has been proven to work , although efficiency to the level required has not yet been accomplished . ETC increases the performance of conventional solid propellants , reduces the effect of temperature on propellant expansion and allows for more advanced , higher density propellants to be used . It will also reduce pressure placed on the barrel in comparison to alternative technologies that offer the same muzzle energy given the fact that it helps spread the propellant ' s gas much more smoothly during ignition . Currently , there are two principal methods of plasma initiation : the flashboard large area emitter ( FLARE ) and the triple coaxial plasma igniter ( TCPI ) . Flashboard large area emitter . Flashboards run in several parallel strings to provide a large area of plasma or ultraviolet radiation and uses the breakdown and vaporization of gaps of diamonds to produce the required plasma . These parallel strings are mounted in tubes and oriented to have their gaps azimuthal to the tube ' s axis . It discharges by using high pressure air to move air out of the way . FLARE initiators can ignite propellants through the release of plasma , or even through the use of ultraviolet heat radiation . The absorption length of a solid propellant is sufficient enough to be ignited by radiation from a plasma source . However , FLARE has most likely not reached optimal design requirements and further understanding of FLARE and how it works is completely necessary to ensure the evolution of the technology . If FLARE provided the XM - 291 gun project with the sufficient radiative heat to ignite the propellant to achieve a muzzle energy of 17 MJ one could only imagine the possibilities with a fully developed FLARE plasma igniter . Current areas of study include how plasma will affect the propellant through radiation , the deliverance of mechanical energy and heat directly and by driving gas flow . Despite these daunting tasks FLARE has been seen as the most plausible igniter for future application on ETC guns . Triple coaxial plasma igniter . A coaxial igniter consists of a fully insulated conductor , covered by four strips of aluminum foil . All of this is further insulated in a tube about 1 . 6 cm in diameter that is perforated with small holes . The idea is to use an electrical flow through the conductor and then exploding the flow into vapor and then breaking it down into plasma . Consequently , the plasma escapes through the constant perforations throughout the insulating tube and initiates the surrounding propellant . A TCPI igniter is fitted in individual propellant cases for each piece of ammunition . However , TCPI is no longer considered a viable method of propellant ignition because it may damage the fins and does not deliver energy as efficiently as a FLARE igniter . Feasibility . The XM - 291 is the best existing example of a working electrothermal - chemical gun . It was an alternate technology to the heavier caliber 140 mm gun by using the dual - caliber approach . It uses a breech that is large enough to accept 140 mm ammunition and be mounted with both a 120 mm barrel and a 135 mm or 140 mm barrel . The XM - 291 also mounts a larger gun tube and a larger ignition chamber than the existing M256 L / 44 main gun . Through the application of electrothermal - chemical technology the XM - 291 has been able to achieve muzzle energy outputs that equate that to a low - level 140 mm gun , while achieving muzzle velocities greater than those of the larger 140 mm gun . Although the XM - 291 does not mean that ETC technology is viable it does offer an example that it is possible . ETC is also a more viable option than other alternatives by definition . ETC requires much less energy input from outside sources , like a battery , than a railgun or a coilgun would . Tests have shown that energy output by the propellant is higher than energy input from outside sources on ETC guns . In comparison , a railgun currently cannot achieve a higher muzzle velocity than the amount of energy input . Even at 50 % efficiency a rail gun launching a projectile with a kinetic energy of 20 MJ would require an energy input into the rails of 40 MJ , and 50 % efficiency has not yet been achieved . To put this into perspective , a rail gun launching at 9 MJ of energy would need roughly 32 MJ worth of energy from capacitors . Current advances in energy storage allow for energy densities as high as 2 . 5 MJ / m³ , which means that a battery delivering 32 MJ of energy would require a volume of 12 . 8 m³ ; this is not a viable volume for use in a modern main battle tank , especially one designed to be lighter than existing models . There has even been discussion about eliminating the necessity for an outside electrical source in ETC ignition by initiating the plasma cartridge through a small explosive force . Furthermore , ETC technology is not only applicable to solid propellants . To increase muzzle velocity even further electrothermal - chemical ignition can work with liquid propellants , although this would require further research into plasma ignition . ETC technology is also compatible with existing projects to reduce the amount of recoil delivered to the vehicle while firing . Understandably , recoil of a gun firing a projectile at 17 MJ or more will increase directly with the increase in muzzle energy in accordance to Newton ' s third law of motion and successful implementation of recoil reduction mechanisms will be vital to the installation of an ETC powered gun in an existing vehicle design . For example , OTO Melara ' s new lightweight 120 mm L / 45 gun has achieved a recoil force of 25 t by using a longer recoil mechanism ( 550 mm ) and a pepperpot muzzle brake . Reduction in recoil can also be achieved through mass attenuation of the thermal sleeve . The ability of ETC technology to be applied to existing gun designs means that for future gun upgrades there ' s no longer the necessity to redesign the turret to include a larger breech or caliber gun barrel . Several countries have already determined that ETC technology is viable for the future and have funded indigenous projects considerably . These include the United States , Germany and the United Kingdom , amongst others . The United States ' XM360 , which is planned to equip the Future Combat Systems Mounted Combat System light tank and may be the M1 Abrams ' next gun upgrade , is reportedly based on the XM291 and may include ETC technology , or portions of ETC technology . Tests of this gun have been performed using " precision ignition " technology , which may refer to ETC ignition .