High Energy Laser (HEL)
A continuous-wave HEL beam is nothing more than a focused ray of optical radiation, which simply delivers heat to the surface of a target.
This technological principle leads to three fundamental operational properties of a HEL:
- The system is line-of-sight, requiring good visibility of the target.
- The time of flight of the beam is effectively nil.
- It delivers only thermal energy on a target’s surface over a non-negligible time scale.
In stark contrast with kinetic weapons, there is henceforth no momentum transfer, no shock wave, no high velocity fragments, and generally no instantaneous effects.
The energy deposited on target is usually cumulative over a few, to tens of seconds.
At the very basic level, the lethality of a HEL weapon system is reduced to whether the target of interest can be neutralized by (over) heating a small area on its surface, as if it were exposed to a blowtorch flame.
It then becomes intuitively easy to list a few sensitive target types, such as explosive devices, where the main charge or the detonator is easily ignited by heat, or control surfaces of aerial vehicles, often fragile and flammable.
Optical sensors and cameras are also inherently sensitive to optical radiation.
Conversely, a system surrounded by layers of insulating, inflammable, and high melting point material is all but immune to surface heating – whether by a laser or a flame.
The main advantages are:
HELs operate at a nearly nil cost-per-shot basis, since the financial burden of an engagement can be reduced to the cost of operating the generator, which provides the required current.
The time-of-flight of a laser beam is instantaneous, which leaves the targeted system with no room to avoid a first strike.
Finally, HELs, by design, can be used at lower power levels than their rated maximum, thus allowing the effects on target to be tailored to the mission and constraints.
It nevertheless goes without saying that these features ought to always be considered in the context of a specific scenario and mission objectives to assess their actual benefit.
As stated earlier, for an array of applications, kinetic weapons will remain the tool of choice for the simple reason that they deliver an explosive warhead, as opposed to only heat.
The ability of a scalable effect on target.
This is a novel, and henceforth arguably yet unexplored concept in weapon systems.
Indeed, kinetic weapons function under the ‘hit-or-miss premise,’ where a warning shot in which the projectile deliberately misses the target yet remains close enough to be noticed, is the only way to deliver a scaled-down message.
Lasers, on the other hand, can operate at any power level up to their rated maximum, which, in specific circumstances, allows tailoring the desired effect.
A HEL system designed for a hard kill of aerial threats could still be used to temporarily dazzle or fry the camera on board a UAV, or an aircraft performing a hostile overfly, without inflicting any kinetic damage.
The ability to undertake such action could have a major impact insofar as avoiding excessive escalation of force in politically delicate circumstances and providing a commander a wider choice of direct action from a single weapon system.
Finally, the availability of a continuous range of power levels from a laser is also tied to their reliability – they tend to suffer from a ‘graceful degradation’ of output powers, instead of catastrophic failures.
HEL lethality is only driven by localized surface deposition of heat, which renders them ineffective against a number of target types.
The amount of energy delivered on target even by state-of-the-art HELs is currently orders of magnitude smaller than that by conventional weapons.
The requirement for sustained firing over seconds also limits their use against fast-moving objects. The physics of atmospheric propagation add an additional challenge for long-range applications insofar as the beam undergoes distortions, which reduces the irradiance (power per surface area) on target.
These are further aggravated in adverse atmospheric conditions, although advances in beam control and laser sources at different wavelengths allow some of the issues to be circumvented.
One particular aspect pertaining to the use of HELs is that of laser safety. With intra-beam irradiances orders of magnitude above laser safety limits, the risk of reflections in the vicinity of the target, and the perception of an ‘infinite’ reach of the laser beam, there has been an understandable mistrust pertaining to the safety aspects of such weapons.
Development of low cost, fast time deployable HEL solutions: The underlying technology for HELs with an output power into the 10s of kW is both commercially available, and already used in a number of military system demonstrators. In parallel, lasers can, to a certain extent, be ‘piggybacked’ to existing targeting and tracking systems. As a result, new HEL defence programs and projects can leverage existing products, thus minimizing the delays and cost overruns associated with the development of emerging technologies.
Products on the market
Currently, there are several products or family products on the market regarding HEL developed mainly for Ground (mobile and Fixed) and Naval platforms.
The HELIOS system from Lockheed Martin is a High Energy Laser with Integrated Optical-dazzler and Surveillance.
It provides the U.S. Navy with game-changing directed energy capability through integration of high energy laser and optical dazzler technology into the ship and combat system.
More than just a high energy laser, the HELIOS system’s multi-mission capabilities include long range Intelligence, Surveillance, Reconnaissance (ISR) and Counter UAS-mounted ISR (C-ISR) Dazzler.
It uses a Laser with a power higher than 100KW.
The HELWS (High Energy Weapon Laser System) is a scalable solution developed by Raytheon form 10 KW up to 100 KW of laser power. It has been tested for land, naval and helo application.
FIRESTRIKE HEL family and RELI (Robust Electric Laser Initiative) Program by Northrop Grumman offers a scalable HEL solution up to 60KW for ground, naval and helicopter/wide body platforms.
CLWS (Compact Laser Weapon Systems) by Boeing offers an extremely compact and deployable solutions well suited for Ground application.
The system is scalable and could be used with a laser power greater than 60KW also for Naval and Avionic platform.