The THEL is to be built in two configurations, the static baseline THEL and relocatable Mobile THEL (MTHEL).
The design aim of the THEL systems is to provide a point defence weapon which is capable of engaging and destroying artiellery rockets (Katyushas), artillery shells, mortar rounds and low flying aircraft.
The THEL demonstrator was trialled repeatedly between 2000 and 2004, destroying 28 122 mm and 160 mm Katyusha rockets, multiple artillery shells, and mortar rounds, including a salvo attack by mortar.
The demonstrator THEL system was built around a deuterium fluoride chemical laser operating at 3.8 microns wavelenght. The combustor in this laser burns ethylene in toxic and corrosive Nitrogen Trifluoride gas to produce the excited deuterium fluoride lasing medium, which is then mixed with deuterium and helium, and fed into expansion nozzles similar to that of other chemical lasers, like the carbon dioxide GDL and COIL. A complex exhaust diffusion and pressure equalisation system must be used, including a neutralisation stage to soak up the highly corrosive and toxic deuterium fluoride exhaust efflux gas.
The first deuterium fluoride laser to be trialled was the US Navy's MIRACL, or Mid-Infrared Advanced Chemical Laser, which was coupled to the Sea Lite Beam Director optical turret. This research system was trialled extensively since 1983 at the High Energy Laser Systems Test Facility (HELSTF Directorate) at White Sands in New Mexico. This was a MegaWatt class weapon.
The THEL program yielded excellent trial results, using a phased array radar to track incoming targets and direct the beam. Unlike the ABL, the THEL is a relatively short range weapon used for the terminal defence of a local area, not unlike a point defence SAM or AAA system.